Title of Invention	A COMBINED PROCESS FOR CONVERTING A COAL LIQUEFIED OIL
Abstract	The present invention relates to a combined process for converting a coal liquefied oil, characterized in that said process comprises a combination of the steps of: (1) hydro-stabilizing the coal liquefied oil; (2) hydro-upgrading the diesel fraction obtained in step (1); and (3) hydrocracking the unconverted oil fraction obtained in step (1). The process can be used for producing a high grade diesel with a maximum yield, wherein the total yield of the diesel is higher than 92% by weight, and the cetane number thereof goes beyond 45.

Title of Invention

A COMBINED PROCESS FOR CONVERTING A COAL LIQUEFIED OIL

Abstract

The present invention relates to a combined process for converting a coal liquefied oil, characterized in that said process comprises a combination of the steps of: (1) hydro-stabilizing the coal liquefied oil; (2) hydro-upgrading the diesel fraction obtained in step (1); and (3) hydrocracking the unconverted oil fraction obtained in step (1). The process can be used for producing a high grade diesel with a maximum yield, wherein the total yield of the diesel is higher than 92% by weight, and the cetane number thereof goes beyond 45.

Full Text	A Combined Process For Converting A Coal Liquefied Oil Technical Field The present invention concerns a process for hydrogenating and hydrocracking the liquid hydrocarbons obtained by a destructive hydrogenation of a coal. More specifically, the present invention relates to a process for converting a coal liquefied oil into diesel with a maximum yield. Background of the Invention As early as 1913, Germany started on the studies of the preparation of liquid hydrocarbon products by directly liquefying coal, and industrialized the technology of preparing gasoline by directly liquefying lignite in 1927. Since the first world oil crisis in 1973, the developed counties attached much importance to the direct coal liquefaction technology, and gradually developed many direct coal liquefaction processes. IGOR technology developed by Germany can be used for in-line refining the coal liquefied oil, so as to directly produce qualified diesel products. The coal liquefied oil produced by other technologies, however, may not become qualified fuel products unless it is subsequently processed. The direct coal liquefied oil retains some features of the coal, such as high olefin and aromatics content, high nitrogen and oxygen content, and worse storage stability. Generally, nitrogen in the coal liquefied oil is in a content of higher than 0.5% by weight; oxygen therein ranges from 1.5% to 7% by weight; and the content of aromatic compounds therein are of 60%-70% by weight. In addition to high content of aromatics and impurities such as nitrogen and oxygen, the coal liquefied oil usually contains fine solid particles (diameter less than 5 urn) and metals (primarily Fe, Ca, Na, etc.), wherein the quantity of solid particles is determined by a solid-liquid separation method in the liquefaction unit, and the metal content is relevant to the coal type and the liquefaction catalyst. These fine particles and metals are derived from the unconverted coal powder and the used liquefaction catalyst. In addition, asphaltenes (C7 insolubles) therein is in a relatively high content, generally more than 0.2% by weight. US4332666 discloses a process for the production of diesel, jet fuel and fuel oil. The feedstock oil in said process is the fraction suitable as a hydrogen donor solvent in the coal liquefied oil. Saturated hydrocarbons are extracted from the hydrogenated product as a diesel, a jet fuel and a fuel oil, and the remaining is used as a hydrogen donor solvent. Summary of the Invention On the basis of the prior art, the object of the present invention is to provide a combined process for converting a coal liquefied oil to obtain diesel with a maximum yield. When the conditions, such as the properties of the oil feedstock, catalysts used and so on, are determined, fields of a given final product resulted from different processes are different. By obtaining diesel with a maximum yield means taking the diesel fraction as the final product, and converting as much as possible a coal liquefied oil feedstock into the diesel fraction. The process of the present invention comprises a combination of the steps of: (1) feeding a coal liquefied oil after filtered together with hydrogen into a hydro-stabilizing reactor, contacting with a hydrogenation guard catalyst and a hydro-stabilizing catalyst therein to conduct reactions, then separating the effluent from the hydro-stabilizing reactor to obtain a gas, a naphtha fraction, a diesel fraction I and an unconverted oil fraction; (2) feeding the diesel fraction I obtained in step (1) together with hydrogen into a hydro-upgrading reactor, contacting with a hydro-upgrading catalyst therein to conduct reactions, then separating the effluent from the hydro-upgrading reactor to obtain a gas, a naphtha fraction, and a diesel fraction II; and (3) feeding the unconverted oil fraction from step (1) together with hydrogen into a hydrocracking reactor, contacting with a hydrocracking catalyst therein, or a combination of a hydrorefining catalyst and a hydrocracking catalyst therein in sequence, to conduct reactions, then separating the effluent from the hydrocracking reactor to obtain a gas, a naphtha fraction, and a diesel fraction III. n step (1), the cut point between the naphtha fraction and the diesel fraction I ranges between 150C and 180C, and the cut point between :he diesel fraction I and the unconverted oil fraction ranges between 520C and 360C. In step (2), the cut point between the naphtha fraction and the diesel Fraction II ranges between 150C and 180 C. tn step (3), the cut point between the naphtha fraction and the diesel fraction III ranges between 150C and 180C, and the cut point between the diesel fraction III and the unconverted oil fraction ranges between 320C: and 360C. Both the diesel fraction II obtained in step (2), and the diesel fraction III obtained in step (3) are the diesel products of the present invention, and they can be mixed together. In a further embodiment, a part of the unconverted oil fraction obtained in step (1) is recycled to the coal liquefaction unit for producing the coal liquefied oil as a hydrogen donor solvent. In a still further embodiment, a high pressure separator is independently used to conduct said separation in each of the steps (1), (2) and (3), and the hydrogen-enriched gas separated from each of the individual high pressure separator is recycled to the corresponding hydrogenation reactor of each step (i.e., hydro-stabilizing reactor, hydro-upgrading reactor and hydrocracking reactor). The direct coal liquefied oil is characterized in a very high aromatics content, and a low content of paraffins. It is very difficult to obtain a diesel fraction having a cetane number above 45 from the direct coal liquefied oil through a conventional hydrorefination method, and the diesel fraction has a very low yield. In the present invention, different processing steps are used, based on the different processing properties and difficulty of processing of the diesel fraction I and the unconverted oil fraction both obtained in step (1). By a reasonable process flow arrangement and an optimized catalyst combination, high quality diesel products of the coal liquefied oil with a maximum yield are obtained. Chemically, it can be seen that the way to increase the cetane number of diesel is to hydrosaturate the poly-aromatics in the diesel fraction to obtain naphthenes, and then form paraffins having a high cetane number from said naphthenes by a cracking and ring-opening reaction. However, as compared with the cracking and ring-opening reaction of the naphthenes, a chain breaking cracking reaction easily occurs with paraffins and naphthenes having a side chain, so as to convert linear high molecules into smaller molecules. Due to the high aromatics content in the coal liquefied oil, a relatively severe reaction condition is needed for greatly increasing the cetane number thereof. However, the more severe the reaction condition is, the easier the linear high molecules are cracked into smaller molecules, so as to reduce the diesel yield. It, thereby, is difficult to maintain a high diesel yield while obtaining a high quality diesel having a higher cetane number. The hydro-upgrading catalyst in step (2) of the present invention has a superior selective-cracking and ring-opening ability, and may promote the ring-opening and cracking reaction of naphthenes, and inhibit the occurrence of the chain breaking cracking reaction. Said catalyst, thereby, may maintain a higher diesel yield while greatly increasing the cetane number thereof. In step (2), the yield of the diesel fraction II can achieve 95% or more, based on the diesel fraction I. The unconverted oil fraction obtained in step (1) is a heavy fraction containing a high content of impurities, especially nitrogen, and a high aromatics content. Since it is difficult to further process said fraction, said fraction is generally used as a hydrogen donor solvent and recycled in its entirety to the coal liquefaction unit. However, in the present invention, the unconverted oil fraction obtained in step (1) can be, partly or wholly, further processed by step (3), and hydrocracked to the diesel fraction III. In step (3), the hydrocracking catalyst has a moderate cracking activity, and a high diesel selectivity. Moreover, said catalyst can be used for not only cracking the unconverted oil fraction into the diesel fraction III having a high cetane number, but also inhibiting the diesel fraction from being cracked into light fractions such as naphtha and the like. The process of the present invention can be used for the production of high quality diesel with a maximum yield. Based on the diesel fraction I and the unconverted oil fraction obtained in step (1), the total yield of the diesel product (the summary of the diesel fractions II and III) is more than 92% by weight. Moreover, said product has an extremely low sulphur and nitrogen content, a relatively low aromatics content, and relatively low density and a cetane number of higher than 45. Accordingly, said product meets the requirements on sulphur, nitrogen and aromatics content for the Category III diesel under the “Worldwide Fuels Charter’. Specifically, the present application involves the following aspects: 1. A combined process for converting a coal liquefied oil, characterized in that said process comprises the combination of the following steps comprising: (1) feeding a coal liquefied oil after filtered together with hydrogen into a hydro-stabilizing reactor, contacting with a hydrogenation guard catalyst and a hydro-stabilizing catalyst therein to conduct reactions, then separating the effluent from the hydro-stabilizing reactor to obtain a gas, a naphtha fraction, a diesel fraction I and an unconverted oil fraction; (2) feeding the diesel fraction I obtained in step (1) together with hydrogen into a hydro-upgrading reactor, contacting with a hydro-up grading catalyst therein to conduct reactions, then separating the effluent from the hydro-upgrading reactor to obtain a gas, a naphtha fraction, and a diesel fraction II; and (3) feeding the unconverted oil fraction from step (1) together with hydrogen into a hydrocracking reactor, contacting with a hydrocracking catalyst therein, or a combination of a hydrorefining catalyst and a hydrocracking catalyst therein in sequence, to conduct reactions, then separating the effluent from the hydrocracking reactor to obtain a gas, a naphtha fraction, and a diesel fraction III. 2. The process according to Aspect 1, characterized in that part of the unconverted oil fraction obtained in step (1), as a hydrogen donor solvent, is recycled to the coal liquefaction unit for producing said coal liquefied oil. 3. The process according to Aspect 1, characterized in that a high pressure separator is independently used to conduct said separation in each of the steps (1), (2) and (3), and the hydrogen-enriched gas separated from each of the individual high pressure separator is recycled to the corresponding hydrogenation reactor of each step, 4. The process according to Aspect 1, characterized in that the hydro-stabilizing reactor is a fixed bed reactor or an expanded bed reactor. 5. The process according to Aspect 1, characterized in that the coal liquefied oil has a distillation range of C5-520C. 6. The process according to Aspect 1, characterized in that the hydro- stabilizing catalyst in step (1) is a catalyst, containing no halogen atoms, wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous alumina or/and a silica-alumina, wherein the Group VIB metal is selected from Mo or/and W, and the Group VIII non- noble metal is selected from Co or/and Ni. 7. The process according to Aspect 1, characterized in that the hydro- stabilizing reaction in step (1) is conducted at a hydrogen partial pressure of 4.0-20.0 MPa, a reaction temperature of 280-450C, a liquid hourly space velocity of 0.1-10 h”1 and a hydrogen/oil ratio of 300-2800 Nm/m3. 8. The process according to Aspect 1, characterized in that the hydro- upgrading catalyst in step (2) is a catalyst, containing a molecular sieve, wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous alumina or/and a silica-alumina, wherein the Group VIB metal is selected from Mo or/and W, and the Group VIII non- noble metal is selected from Co or/and Ni. 9. The process according to Aspect 1, characterized in that the hydro- upgrading reaction in step (2) is conducted at a hydrogen partial pressure of 6.0-20.0 MPa, a reaction temperature of 280-450°C, a liquid hourly space velocity of 0.1-20 h-1 and a hydrogen/oil ratio of 400-3000 Nm/m3. 10. The process according to Aspect 1, characterized in that the hydrocracking reaction in step (3) is conducted in a single-stage and single-catalyst mode, wherein the hydrocracking catalyst used is a catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous silica-alumina or an amorphous silica- magnesia, wherein the Group VIB metal is selected from Mo or/and W, and the Group VIII non-noble metal is selected from Co or/and Ni. 11. The process according to Aspect 1, characterized in that the hydro cracking reaction in step (3) is conducted in a single-stage and double-catalysts mode, wherein the hydrorefining catalyst is filled before the hydrocracking catalyst, the hydrorefining catalyst is a catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous alumina or/and a silica-alumina, wherein the Group VIB metal is selected from Mo or/and W, and the Group VIII non-noble metal is selected from Co or/and Ni; and the hydrocracking catalyst is a catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on a Zeolite Y, wherein the Group VIB metal is selected from Mo or/and W, and the Group VIII non-noble metal is selected from Co or/and Ni; 12. The process according to Aspect 1, characterized in that the hydrocracking reaction in step (3) is conducted at a hydrogen partial pressure of 4.0-20.0 MPa, a reaction temperature of 280-450 C, a liquid hourly space velocity of 0.1-20 h-1 and a hydrogen/oil ratio of 300-2000 Nm3/m3. Description of Drawings Fig. 1 outlines the diagram of the combined process for converting the coal liquefied oil with a maximum yield according to the present invention. Detailed Description of the Invention The process of the present invention comprises hydro-stabilizing of a coal liquefied oil, hydro-upgrading of a diesel fraction I from the hydro-stabilizing, and hydrocracking of an unconverted oil fraction from the hydro-stabilizing, and the flow chart of each portion is described as follows, (I) hydro-stabilizing of the coal liquefied oil Hydrorefining method is used to saturate olefins and remove heteroatoms such as oxygen, nitrogen and the like, so as to increase the stability of the coal liquefied oil as the main object. Accordingly, the method is usually called as the process for hydro-stabilizing. After filtration by a filtering device, the coal liquefied oil produced in a coal liquefaction unit is mixed with hydrogen, and heated to a required reaction temperature, and fed into a hydro-stabilizing reactor. The effluent from the hydro-stabilizing reactor primarily comprises H2, light hydrocarbons, H2S, NH3, water and hydro-stabilized oils. The effluent from the hydro-stabilizing reactor is fed in sequence into a high pressure separator, a low pressure separator and a distillation tower. Through the separation system and fractionation system are separated a gas (including a hydrogen-enriched gas separated from the high pressure separator, and light hydrocarbons), a naphtha fraction (including a light and a heavy naphtha fraction), a diesel fraction I and an unconverted oil fraction, wherein the diesel fraction I obtained thereby is fed into a hydro-upgrading unit, a part or all of the unconverted oil fraction obtained thereby is fed into a hydrocracking unit. In another embodiment, a part of the unconverted oil fraction is recycled as a hydrogen donor solvent to said coal liquefaction unit. In another embodiment, said hydrogen-enriched gas is mixed with fresh hydrogen, and then sent to the hydro-stabilizing reactor. (II) hydro-upgrading of the diesel fraction I from the hydro-stabilizing unit The diesel fraction I produced in the hydro-stabilizing unit is fed into the hydro-upgrading unit, so as to increase the cetane number of the diesel. The hydro-upgrading unit has a similar process flow to the hydro-stabilizing unit, i.e., mixing the diesel fraction from the hydrostabilized products with hydrogen, and conducting reactions in the hydro-upgrading reactor. The effluent from the hydro-upgrading reactor is fed in sequence into a high pressure separator, a low pressure separator and a distillation tower. Through the separation system and fractionation system are separated a gas (including a hydrogen-enriched gas separated from the high pressure separator, and light hydrocarbons), a naphtha fraction (including a light and a heavy naphtha fraction) and a diesel fraction II. In another embodiment, said hydrogen-enriched gas is mixed with fresh hydrogen, and then sent to the hydro-upgrading reactor. (III) hydrocracking of the unconverted oil fraction from the hydro-stabilizing unit The unconverted oil fraction produced in the hydro-stabilizing unit is sent to the hydrocracking unit. Under the circumstance that an amorphous hydrocracking catalyst is used in the hydrocracking unit, the process flow thereof is similar to those of the aforesaid two hydrogenation, except for setting up a hydrocracking reactor therein (operated in a single-stage and single-catalyst mode). The unconverted oil fraction from the hydro-stabilizing unit is mixed with hydrogen, and reactions is conducted in the hydrocracking reactor. The effluent from the hydrocracking reactor is fed in sequence into a high pressure separator, a low pressure separator and a distillation tower. Through the separation system and fractionation system are separated a gas (including a hydrogen-enriched gas separated from the high pressure separator, and light hydrocarbons), a naphtha fraction (including a light and a heavy naphtha fraction) and a diesel fraction III. In another embodiment, said hydrogen-enriched gas is mixed with fresh hydrogen, and then sent to the hydrocracking reactor. Under the circumstance that a molecular sieve type catalyst having a good diesel fraction selectivity is used in the hydrocracking process, a hydrorefining reactor and a hydrocracking reactor (operated in a single-stage and double-catalyst mode) are set up in the process flow. At this time, the hydro-stabilized unconverted oil fraction is mixed with hydrogen, and fed into the hydrorefining reactor. The effluent from the hydrorefining reactor primarily comprises H2S, NH3 and hydro-refined oils. Without a gas-liquid separation, the effluent from the hydrorefining reactor is directly fed into the hydrocracking reactor, in which ring-opening, chain-breaking and hydro-saturating reactions occur. The effluent from the hydrocracking reactor primarily comprises H2, light hydrocarbons, H2S, NH3 and hydrocracked product oils. Said effluent is fed in sequence into a high pressure separator, a low pressure separator and a distillation tower. Through the separation system and fractionation system are separated a gas (including a hydrogen-enriched gas separated from the high pressure separator, and light hydrocarbons), a naphtha fraction (including a light and a heavy naphtha fraction) and a diesel fraction III. Under the circumstance that the hydrocracking process is performed in a recycle mode, an unconverted oil fraction is further separated from the distillation tower, and then recycled to the inlet of the hydrocracking reactor. Both the diesel fractions II and III are the diesel products of the present invention, and they may be used together. There is no particular limitation for the distillation range of the coal liquefied oil feedstock used in the present invention. Generally, it is C5-520˚C:, preferably C5-480˚C (ASTM D-1160). The heavier the fraction is, the higher the content of the impurities such as metals and asphaltenes, and the worse the effects on the of the hydrogenate catalyst life is. Nitrogen content in the feedstock is usually not more than 1.2 % by weight, preferably not more than 0.8 % by weight, and sulphur content therein is usually not more than 2.0 % by weight. In the process of the present invention, the hydro-stabilizing reaction in the hydro-stabilizing reactor is conducted at a hydrogen partial pressure of 4.0-20.0 MPa, a reaction temperature of 280-450˚C, a liquid hourly space velocity of 0.1-10 h-1 and a hydrogen/oil ratio of 300-2800 Mm3/m3. The hydro-upgrading reaction in the hydro-upgrading reactor is conducted at a hydrogen partial pressure of 6.0-20.0 MPa, a reaction temperature of 280-450˚C:, a liquid hourly space velocity of 0.1-20 h-1 and a hydrogen/oil ratio of 400-3000 Mm3/m3. The hydrocracking reaction in the hydrocracking reactor (including the single-stage and single-catalyst mode, and the single-stage and double-catalysts mode) of the present invention is conducted at a hydrogen partial pressure of 4.0-20.0 MPa, a reaction temperature of 280-450˚C, liquid hourly space velocity of 0.1-20 h’1 and a hydrogen/oil ratio of 500-2000 Mm3/m3. There is no particular limitation for the hydro-stabilizing catalyst used therein. A catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous alumina or/and a silica- alumina, which contains no halogen atoms, may be used. Such a catalyst has a very strong hydrodenitrogenation activity. In addition, said Group VIB metal is not specially limited, but is preferably Mo or/and W; and said Group VIII non-noble metal is not specially limited, but is preferably Co or/and Ni. Due to a certain amount of metals and asphaltenes in the coal liquefied oil, a suitable amount of hydrogenation guard catalysts may be filled from the top of the hydro-stabilizing catalyst. The amount filled is determined by the impurity content in the coal liquefied oil and the operation period of the unit, which is known for those skilled in the art. Generally, the volume ratio of said hydrogenation guard catalyst to said hydro-stabilizing catalyst is from 0.03 to 0.35. The hydro-upgrading catalyst used therein may be a catalyst, containing a molecular sieve, wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous alumina or/and a silica-alumina, wherein the Group VIB metal is not particularly limited, but is preferably Mo or/and W, and the Group VIII non-noble metal is not particularly limited, but is preferably Co or/and Ni. The hydrocracking process may be operated in a single-stage and single-catalyst mode, or in a single-stage and double-catalysts mode. When a single-stage and single-catalyst mode is used, the hydrocracking catalyst may be a catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous silica-alumina or an amorphous silica-magnesia or other modified alumina, wherein the Group VIB metal is not particularly limited, but is preferably Mo or/and W, and the Group VIII non-noble metal is not particularly limited, but is preferably Co or/and Ni. When a single-stage and double-catalysts mode is used, a hydrorefining catalyst is filled prior to the hydrocracking catalyst. The hydrorefining catalyst may be a catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous alumina or a silica-alumina, wherein the Group VIB metal is not particularly limited, but is preferably Mo or/and W, and the Group VIII non-noble metal is not particularly limited, but is preferably Co or/and Ni. In addition, the hydrocracking catalyst may be a catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on a Zeolite Y, wherein the Group VIB metal is not particularly limited, but is preferably Mo or/and W, and the Group VIII non-noble metal is not particularly limited, but is preferably Co or/and Ni. In the present invention, a hydro-upgrading unit and a hydrocracking unit are used respectively for processing the diesel fraction I and the unconverted oil fraction from the hydrostabilized product. The hydro-upgrading unit is used for processing the diesel fraction I from the hydrostabilized product, so as to reduce the aromatics content, and achieve the object of reducing the diesel fraction density and greatly increasing the cetane number of the diesel fraction by moderate degree of ring-opening. The yield of the diesel fraction II obtained thereby can reach 95 % by weight or above. In addition, the hydrocracking unit is used for processing the unconverted oil fraction, so as to convert the relatively heavy fraction into a naphtha fraction, and a diesel fraction HI having a low content of impurities such as sulphur and nitrogen and having a high cetane number. Both the diesel fractions II and III are the diesel products of the present invention, and they can be used together. If the aforesaid processing routine is used, diesel products are produced from the coal liquefied oil in a high yield, and the sulphur, nitrogen and aromatics content thereof may satisfy the standard of Category III oils under “Worldwide Fuels Charter”. In addition, the product has a cetane number of higher than 45. Preferably, the catalyst used for the hydro-upgrading has a well balanced hydrogenating activity and ring-opening cracking activity. It, thereby, is suitable for processing aromatics having two rings or more, and increasing the cetane number thereof by ring-opening. It is know that an aromatics hydrosaturation precedes a ring-opening reaction. Therefore, firstly, said catalyst should have a good hydrorefining properties, i.e., saturating properties, so as to provide the cracking reaction with reactants that a ring-opening reaction is easily to occur therewith. Then, in addition to the saturating property, the catalyst should show a selectivity with respect to a ring-opening and cracking reaction and be capable to disturb the balance in a hydro-saturating reaction, so as to achieve the object of changing the structures of hydrocarbons and increasing the cetane number thereof. The cracking function of a catalyst contributes to its acidic components, which are easily subject to poisons (for example, nitrides) and then deactivated. High nitrogen content is another feature of the diesel from a coal liquefied oil. In order to reduce the effects brought by the high nitrogen content, a relatively high hydrocracking activity is needed for the catalyst. Finally, the hydrogenating activity of the catalyst must match with its cracking activity. If there are a low hydrogenating activity and a high cracking activity, aromatics cannot be well saturated. Accordingly, reactants for use with the ring-open reaction cannot be obtained in a large amount, easily rendering cracking of “useful” hydrocarbons such as linear paraffins, producing of smaller molecules, and decreasing of the yield of the diesel. If there are a high hydrogenating activity and a low cracking activity, the hydrosaturating reaction proceeds to a deepened degree so that the aromatics are completely hydrogenated, while the ring-opening reaction goes forward insufficient, which will increase the hydrogen consumption, whereas the cetane number is not greatly increased. The hydrocracking unit may be operated in a one-pass mode, or a recycle mode. The hydrocracking unit may use an amorphous hydrocracking catalyst, and be operated in a single-stage and single-catalyst mode. It may also use a molecular sieve type catalyst having a good diesel fraction selectivity, and be operated in a single-stage and double-catalysts mode. In the hydrogenation process of the coal liquefied oil, the unit is used to convert the unconverted oil fraction into a light oil fraction and produce no a further unconverted oil fraction, so as to convert, to a maximum extent, the coal liquefied oil into a light oil fraction and produce a diesel product from the coal liquefied oil as much as possible. Since the coal liquefied oil contains a great amount of aromatics and nitrogen, it is very difficult to refine them with conventional processes. The feature of the present process lies in a reasonable combination of the hydro-stabilizing unit, the hydro-upgrading unit and the hydrocracking unit. In the present invention, difficulties that may occur in the processing are will distributed across the process, resulting in an optimized unit performance. For example, if the properties of the feedstock for the hydro-stabilizing become worse, the optimized unii performance can be maintained by increasing the severity of the hydro-stabilizing and the hydrocracking to an acceptable level. Moreover, by suitably adjusting the cut point between the diesel fraction I and the unconverted oil fraction from the hydro-stabilizing unit, the content of impurities in the diesel fraction I can be kept at a stable level, so as to maintain the stability of the operating conditions of the hydro-upgrading unit. The process of the present invention is further explained by referring to the drawing, but is not used to limit the present invention. The accompanying drawing, which is included to provide a further understanding of the invention and is incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention. Fig. 1 shows the diagram of the combined process for converting the coal liquefied oil with a maximum yield according to the present invention. Many essential equipments, such as pumps, air coolers and valves, are omitted from Fig. 1. The invention is described more fully hereinafter with reference to the accompanying drawing, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. The flow chart of the process is detailed as follows. A coal liquefied oil is fed into filter 3 via pipeline 1 and filtrated. After the pressure is increased to a required reaction pressure by a feedstock pump, it is then mixed with hydrogen from pipeline 6, heat-exchanged with a heat exchanger 4, heated via a heating furnace 7, and fed into a hydro-stabilizing reactor 9. The thus obtained mixture contacts with a hydrogenation guard catalyst bed and a hydro-stabilizing catalyst bed to remove metals and impurities from the oil feedstock, such as sulphur, nitrogen and the like. Cold hydrogen needs to be introduced into the middle of the reactor to control the reaction temperature since a hydrorefining reaction is a strong exothermic one. The effluent from the hydro-stabilizing reactor 9 is fed via pipeline 8 into the heat-exchanger 4 for heat-exchanging, and then fed into a high pressure separator 10 in which it is divided into two streams, wherein one of them is a hydrogen-enriched gas comprising hydrogen as a main component, and some hydrogen sulfide and ammonia. Said hydrogen-enriched gas is compressed via a recycle compressor, and mixed via pipeline 5 with fresh hydrogen from pipeline 2, and then recycled to the reactor 9 via pipeline 6. The other stream is fed into a low pressure separator 12 via pipeline H to further remove light hydrocarbons. The light hydrocarbons are discharged from the unit via pipeline 13. The effluent from the bottom of the low pressure separator 12 is fed via pipeline 14 into a distillation tower 15 to obtain a naphtha fraction, a diesel fraction I and an unconverted oil fraction, wherein the naphtha fraction is discharged from the unit via pipeline 16, and the diesel fraction I and the unconverted oil fraction are fed into a hydro-upgrading unit and a hydrocracking unit respectively via pipelines 17 and 18. The diesel fraction I is fed into a buffer tank 19 via pipeline 17. After the pressure is increased to a required reaction pressure by a feedstock pump, it is then mixed with hydrogen from pipeline 20, heat-exchanged with a heat exchanger 21, fed via pipeline 22 into a heating furnace 23, and then fed into a hydro-upgrading reactor 24. The thus obtained mixture contacts with a hydro-upgrading catalyst bed to further remove impurities, such as sulphur, nitrogen and the like, saturate aromatics therein, and conduct a ring-opening reaction to some extent. Although the ring-opening reaction is an endothermic one, the reaction as a whole is still an exothermic one since the hydrorefining reaction is a strong exothermic one. Cold hydrogen needs to be introduced into the middle of the reactor to control the reaction temperature. The effluent from the hydro-upgrading reactor 24 is fed via pipeline 25 into the heat-exchanger 21 for heat-exchanging, and then fed into a high pressure separator 26 in which it is divided into two streams, wherein one of them is a hydrogen-enriched gas comprising hydrogen as a main component, and some hydrogen sulfide, ammonia and light hydrocarbons produced by the cracking. Said hydrogen-enriched gas is compressed via a recycle compressor, and mixed via pipeline 27 with fresh hydrogen from pipeline 2, and then recycled to the reactor 24 via pipeline 20. The other stream is fed into a low pressure separator 29 via pipeline 28 to further remove light hydrocarbons. The light hydrocarbons are discharged from the unit via pipeline 30. The effluent from the bottom of the low pressure separator 29 is fed via pipeline 31 into a distillation tower 32, and the naphtha fraction and the diesel fraction II fractionated therein are drawn out of the unit respectively via pipelines 33 and 34. If the hydrocracking is in a single-stage and double-catalysts mode, the hydrostabilized unconverted oil fraction is fed into a buffer tank 35 via pipeline 17. After the pressure is increased to a required reaction pressure by a feedstock pump, it is then mixed with hydrogen from pipeline 36, heat-exchanged via a heat exchanger 37, heated via a heating furnace 39, and then fed into a hydrorefining reactor 40. The thus obtained mixture contacts with a hydrorefining catalyst bed to remove impurities, such as sulphur, nitrogen and the like, partly saturate aromatics therein, and crack the heavy fractions to a less degree. Since hydrorefining reaction is a strong exothermic one, cold hydrogen needs to be introduced into the middle of the reactor to control the reaction temperature. The effluent from the hydrorefining reactor 40 is fed via pipeline 41 into a hydrocracking reactor 42 to crack the heavy components into a desired light product by contacting with a hydrocracking catalyst. As with the hydrorefining, cold hydrogen needs to be introduced into the hydrocracking reaction so as to prevent the reaction temperature from increasing to an undesired degree since it is an exothermic reaction. The effluent from the hydrocracking reactor 42 is fed via pipeline 43 into a heat exchanger 37 for heat exchanging, and then fed into a high pressure reactor 44 in which it is divided into two streams, wherein one of them is a hydrogen-enriched gas comprising hydrogen as a main component, and some hydrogen sulfide, ammonia and light hydrocarbons produced by the cracking. Said hydrogen-enriched gas is compressed via a recycle compressor, and mixed via pipeline 45 with fresh hydrogen from pipeline 2, and then recycled to the reactor 40 via pipeline 36. The other stream is fed into a low pressure separator 47 via pipeline 46 to further remove light hydrocarbons. The light hydrocarbons are discharged from the unit via pipeline 49. The effluent from the bottom of the low pressure separator 47 is fed via pipeline 48 into a distillation tower 50, and the naphtha fraction and the diesel fraction III fractionated therein are drawn out of the unit respectively via pipelines 51 and 52. If the hydrocracking is a recycle process, a further unconverted oil fraction will be fractionated from the fractionating system 50. The unconverted oil fraction is recycled via pipeline 53 to the hydrocracking reactor 42 for further hydrocracking. If the hydrocracking is a single-stage and single-catalyst process without the hydrorefining reactor 40, the unconverted oil fraction feedstock from the hydro-stabilizing unit passes in sequence through pipeline 17, buffer tank 35, heat exchanger 37, and heating furnace 39, and then is fed into the hydrocracking reactor 42. Although the hydro-stabilizing reactor is described above using a fixed bed reactor as an example, said hydro-stabilizing reactor may be an expanded bed reactor in another optional embodiment The expanded bed reactor has the following features: (1) The oil feedstock and hydrogen are fed from the bottom of the reactor, and the reaction product is discharged from the top thereof, i.e., feeding the feedstock from the bottom and discharging the product from the top. The feedstock distributing plate of the reactor is located at the bottom of the reactor. Generally, a porous structure is used to realize a uniform distribution of the feedstock. (2) The catalyst bed has an expansion volume ratio of not more than 5%. (3) There is no mass recycle in said expanded bed reactor, unnecessary for an external recycle pump and for an in-line replacement of the catalyst. When an expanded bed reactor is used, the coal liquefied oil after filtration is fed together with hydrogen from the bottom of the reactor into the reactor to hydro-stabilize the coal liquefied oil. In the present invention, the coal liquefied oil feedstock can be hydro-stabilized by using an in-line or off-line method. When an in-line method is used, a part of the unconverted oil fraction from the hydro-stabilizing is recycled as a hydrogen donor agent back to the coal liquefaction unit for producing the coal liquefied oil feedstock. The process of the present invention can be used for the production of a high quality diesel from a coal liquefied oil. Based on the diesel fraction I and the unconverted oil fraction obtained from the hydro-stabilizing unit, the total yield of the diesel product (sum of the diesel fractions II and III) is more than 92 % by weight. Moreover, said product has an extremely low sulphur and nitrogen content, a relatively low aromatics content, a relatively low density and a cetane number of higher than 45. Accordingly, said product meets the requirements on sulphur, nitrogen and aromatics content with respect to the Category III diesel under the “Worldwide Fuels Charter”. Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. Example The following example is used to further disclose the process, but is not used to limit the invention. Both of the coal liquefied oil feedstock A and B in the Examples are filtered, and the properties thereof are listed in Table 1. In addition, the hydrogenation guard catalyst, the hydro-stabilizing catalyst, the hydro-upgrading catalyst, the hydrorefining catalyst and the hydrocracking catalyst used therein are all produced by the Sinopec Changling Catalyst Factory, and the experiment was conducted on a pilot plant-scale fixed bed hydrogenation unit. The density of the coal liquefied oil feedstock, the unconverted oil fraction and the diesel fraction is determined by a hydrometer method, and under the Chinese national standard of GB/T 1884-92 (equivalent to ASTM D4052-95). The sulphur content in the coal liquefied oil feedstock is determined by an energy-dispersive X-ray fluorescence spectrometry, and under the Chinese national standard of GB/T 17040-1997 (equivalent to ASTM D4294-90). The nitrogen content in the coal liquefied oil feedstock is determined by a chemiluminescent method, and under the Chinese standard of SH/T 0704-2001 (equivalent to ASTM D5762-98). The total aromatics content and the polycyclic aromatics content in the coal liquefied oil feedstock and the unconverted oil fraction are determined by a mass spectrography, and under the Chinese standard of RIPP 160-90 (equivalent to ASTM D3239). The total aromatics content and the polycyclic aromatics content in the diesel fraction are determined by a mass spectrography, and under the Chinese standard of SH/T 0606-94 (equivalent to ASTM D2425). The distillation range of the coal liquefied oil feedstock and the unconverted oil fraction is determined by a vacuum distillation method, and under the Chinese national standard of GB/T 9168-1997 (equivalent to ASTM Dl 160-95). The hydrogen content in the unconverted oil fraction is determined by an element analyzer, and under the Chinese standard of SH/T 0656-1998 (equivalent to ASTM D5291-01). The distillation range of the diesel fraction is determined by a distillation method for petroleum products, and under the Chinese national standard of GB/T 6536-1997 (equivalent to ASTM D86-95). The sulphur content of the diesel fraction is determined by a microcoulometric method, and under the Chinese standard of SH/T 0253-92 (equivalent to ASTM D3120-82). The nitrogen content of the diesel fraction is determined by a chemiluminescent method, and under the Chinese standard of SH/T 0657-1998 (equivalent to ASTM D4629-86). The cetane number of the diesel fraction is determined by using a method for determining the igniting property of a diesel, and under the Chinese national standard of GB/T 386-91 (equivalent to ASTM D613- 86). Example 1 The experimental feedstock is the coal liquefied oil A; the hydrogenating guard catalyst is RG10-A and RG10-B, and the hydro- stabilizing catalyst is RJW-2. The hydro-upgrading catalyst for the hydro-upgrading is RIC-1; the hydrocracking is performed in a single-stage and double-catalysts mode and by a one-pass process; the hydrorefining catalyst is RN-10, the hydrocracking catalyst is RT-5. The hydro-stabilizing reaction conditions and the properties of the unconverted oil fraction can be found in Table 2, and the hydro-upgrading and hydrocracking reaction conditions and the properties of the diesel fraction can be found in Table 3. It can be seen from the tables that the density of the coal liquefied oil is at an acceptable level, and the hydro-upgrading conditions are relatively moderate. The unconverted oil fraction in the hydrostabilized product is a suitable hydrogen donor solvent. The diesel fractions from the hydro-upgrading unit and the hydrocracking unit have a very low nitrogen and sulphur content and a relatively low aromatics content, and meets the requirements with respect to the Category III diesel under the “Worldwide Fuels Charter”. The cetane number thereof goes beyond 45, which shows that it is a qualified diesel product. In addition, the diesel fraction from the hydro-upgrading unit has a yield of more than 95 % by weight, and the diesel fraction from the hydrocracking unit has a yield of more than 90% by weight, which both achieve the object of converting a coal liquefied oil into the diesel as much as possible. Example 2 The experimental feedstock is the coal liquefied oil B; the hydrogenating guard catalyst is RG10-A and RG10-B, and the hydro-stabilizing catalyst is RJW-2. The hydro-upgrading catalyst for the hydro-upgrading is RIC-1; the hydrocracking is performed in a single-stage and double-catalysts mode and by a one-pass process; the hydrorefining catalyst is RN-10, the hydrocracking catalyst is RT-5. The hydro-stabilizing reaction conditions and the properties of the unconverted oil fraction can be found in Table 2, and the hydro-upgrading and hydrocracking reaction conditions and the properties of the diesel fraction can be found in Table 3. It can be seen from the tables that the density of the coal liquefied oil is close to 1, and the hydro-upgrading conditions are relatively moderate. The unconverted oil fraction from the hydro-stabilizing is a suitable hydrogen donor solvent. The diesel fractions from the hydro-upgrading unit and the hydrocracking unit have a very low nitrogen and sulphur content and a relatively low aromatics content, and meets the requirements with respect to the Category III diesel under the “Worldwide Fuels Charter”. The cetane number thereof goes beyond 45, which shows that it is a qualified diesel product. In addition, the diesel fraction from the hydro-upgrading unit has a yield of more than 95 % by weight, and the diesel fraction from the hydrocracking unit has a yield of more than 88 % by weight. It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Full Text

A Combined Process For Converting A Coal Liquefied Oil
Technical Field
The present invention concerns a process for hydrogenating and hydrocracking the liquid hydrocarbons obtained by a destructive hydrogenation of a coal. More specifically, the present invention relates to a process for converting a coal liquefied oil into diesel with a maximum yield.
Background of the Invention
As early as 1913, Germany started on the studies of the preparation of liquid hydrocarbon products by directly liquefying coal, and industrialized the technology of preparing gasoline by directly liquefying lignite in 1927. Since the first world oil crisis in 1973, the developed counties attached much importance to the direct coal liquefaction technology, and gradually developed many direct coal liquefaction processes. IGOR technology developed by Germany can be used for in-line refining the coal liquefied oil, so as to directly produce qualified diesel products. The coal liquefied oil produced by other technologies, however, may not become qualified fuel products unless it is subsequently processed.
The direct coal liquefied oil retains some features of the coal, such as high olefin and aromatics content, high nitrogen and oxygen content, and worse storage stability. Generally, nitrogen in the coal liquefied oil is in a content of higher than 0.5% by weight; oxygen therein ranges from 1.5% to 7% by weight; and the content of aromatic compounds therein are of 60%-70% by weight. In addition to high content of aromatics and impurities such as nitrogen and oxygen, the coal liquefied oil usually contains fine solid particles (diameter less than 5 urn) and metals (primarily Fe, Ca, Na, etc.), wherein the quantity of solid particles is determined by a solid-liquid separation method in the liquefaction unit, and the metal content is relevant to the coal type and the liquefaction catalyst. These fine particles and metals are derived from the unconverted coal powder and the used liquefaction catalyst. In addition, asphaltenes (C7 insolubles) therein is in a relatively high

content, generally more than 0.2% by weight.
US4332666 discloses a process for the production of diesel, jet fuel and
fuel oil. The feedstock oil in said process is the fraction suitable as a
hydrogen donor solvent in the coal liquefied oil. Saturated
hydrocarbons are extracted from the hydrogenated product as a diesel, a
jet fuel and a fuel oil, and the remaining is used as a hydrogen donor
solvent.
Summary of the Invention
On the basis of the prior art, the object of the present invention is to provide a combined process for converting a coal liquefied oil to obtain diesel with a maximum yield. When the conditions, such as the properties of the oil feedstock, catalysts used and so on, are determined, fields of a given final product resulted from different processes are different. By obtaining diesel with a maximum yield means taking the diesel fraction as the final product, and converting as much as possible a coal liquefied oil feedstock into the diesel fraction. The process of the present invention comprises a combination of the steps of:
(1) feeding a coal liquefied oil after filtered together with hydrogen into a hydro-stabilizing reactor, contacting with a hydrogenation guard catalyst and a hydro-stabilizing catalyst therein to conduct reactions, then separating the effluent from the hydro-stabilizing reactor to obtain a gas, a naphtha fraction, a diesel fraction I and an unconverted oil fraction;
(2) feeding the diesel fraction I obtained in step (1) together with hydrogen into a hydro-upgrading reactor, contacting with a hydro-upgrading catalyst therein to conduct reactions, then separating the effluent from the hydro-upgrading reactor to obtain a gas, a naphtha fraction, and a diesel fraction II; and
(3) feeding the unconverted oil fraction from step (1) together with hydrogen into a hydrocracking reactor, contacting with a hydrocracking catalyst therein, or a combination of a hydrorefining catalyst and a hydrocracking catalyst therein in sequence, to conduct reactions, then separating the effluent from the hydrocracking reactor to obtain a gas, a naphtha fraction, and

a diesel fraction III.
n step (1), the cut point between the naphtha fraction and the diesel fraction I ranges between 150C and 180C, and the cut point between :he diesel fraction I and the unconverted oil fraction ranges between 520C and 360C.
In step (2), the cut point between the naphtha fraction and the diesel Fraction II ranges between 150C and 180 C.
tn step (3), the cut point between the naphtha fraction and the diesel fraction III ranges between 150C and 180C, and the cut point between the diesel fraction III and the unconverted oil fraction ranges between 320C: and 360C.
Both the diesel fraction II obtained in step (2), and the diesel fraction III obtained in step (3) are the diesel products of the present invention, and they can be mixed together.
In a further embodiment, a part of the unconverted oil fraction obtained in step (1) is recycled to the coal liquefaction unit for producing the coal liquefied oil as a hydrogen donor solvent.
In a still further embodiment, a high pressure separator is independently used to conduct said separation in each of the steps (1), (2) and (3), and the hydrogen-enriched gas separated from each of the individual high pressure separator is recycled to the corresponding hydrogenation reactor of each step (i.e., hydro-stabilizing reactor, hydro-upgrading reactor and hydrocracking reactor).
The direct coal liquefied oil is characterized in a very high aromatics content, and a low content of paraffins. It is very difficult to obtain a diesel fraction having a cetane number above 45 from the direct coal liquefied oil through a conventional hydrorefination method, and the diesel fraction has a very low yield. In the present invention, different processing steps are used, based on the different processing properties and difficulty of processing of the diesel fraction I and the unconverted oil fraction both obtained in step (1). By a reasonable process flow arrangement and an optimized catalyst combination, high quality diesel products of the coal liquefied oil with a maximum yield are obtained. Chemically, it can be seen that the way to increase the cetane number of diesel is to hydrosaturate the poly-aromatics in the diesel fraction to

obtain naphthenes, and then form paraffins having a high cetane number from said naphthenes by a cracking and ring-opening reaction. However, as compared with the cracking and ring-opening reaction of the naphthenes, a chain breaking cracking reaction easily occurs with paraffins and naphthenes having a side chain, so as to convert linear high molecules into smaller molecules. Due to the high aromatics content in the coal liquefied oil, a relatively severe reaction condition is needed for greatly increasing the cetane number thereof. However, the more severe the reaction condition is, the easier the linear high molecules are cracked into smaller molecules, so as to reduce the diesel yield. It, thereby, is difficult to maintain a high diesel yield while obtaining a high quality diesel having a higher cetane number. The hydro-upgrading catalyst in step (2) of the present invention has a superior selective-cracking and ring-opening ability, and may promote the ring-opening and cracking reaction of naphthenes, and inhibit the occurrence of the chain breaking cracking reaction. Said catalyst, thereby, may maintain a higher diesel yield while greatly increasing the cetane number thereof. In step (2), the yield of the diesel fraction II can achieve 95% or more, based on the diesel fraction I. The unconverted oil fraction obtained in step (1) is a heavy fraction containing a high content of impurities, especially nitrogen, and a high aromatics content. Since it is difficult to further process said fraction, said fraction is generally used as a hydrogen donor solvent and recycled in its entirety to the coal liquefaction unit. However, in the present invention, the unconverted oil fraction obtained in step (1) can be, partly or wholly, further processed by step (3), and hydrocracked to the diesel fraction III. In step (3), the hydrocracking catalyst has a moderate cracking activity, and a high diesel selectivity. Moreover, said catalyst can be used for not only cracking the unconverted oil fraction into the diesel fraction III having a high cetane number, but also inhibiting the diesel fraction from being cracked into light fractions such as naphtha and the like.
The process of the present invention can be used for the production of high quality diesel with a maximum yield. Based on the diesel fraction I and the unconverted oil fraction obtained in step (1), the total yield of

the diesel product (the summary of the diesel fractions II and III) is more than 92% by weight. Moreover, said product has an extremely low sulphur and nitrogen content, a relatively low aromatics content, and relatively low density and a cetane number of higher than 45. Accordingly, said product meets the requirements on sulphur, nitrogen and aromatics content for the Category III diesel under the “Worldwide Fuels Charter’. Specifically, the present application involves the following aspects:
1. A combined process for converting a coal liquefied oil, characterized in that said process comprises the combination of the following steps comprising:
(1) feeding a coal liquefied oil after filtered together with hydrogen into a hydro-stabilizing reactor, contacting with a hydrogenation guard catalyst and a hydro-stabilizing catalyst therein to conduct reactions, then separating the effluent from the hydro-stabilizing reactor to obtain a gas, a naphtha fraction, a diesel fraction I and an unconverted oil fraction;
(2) feeding the diesel fraction I obtained in step (1) together with hydrogen into a hydro-upgrading reactor, contacting with a hydro-up grading catalyst therein to conduct reactions, then separating the effluent from the hydro-upgrading reactor to obtain a gas, a naphtha fraction, and a diesel fraction II; and
(3) feeding the unconverted oil fraction from step (1) together with hydrogen into a hydrocracking reactor, contacting with a hydrocracking catalyst therein, or a combination of a hydrorefining catalyst and a hydrocracking catalyst therein in sequence, to conduct reactions, then separating the effluent from the hydrocracking reactor to obtain a gas, a naphtha fraction, and a diesel fraction III.

2. The process according to Aspect 1, characterized in that part of the unconverted oil fraction obtained in step (1), as a hydrogen donor solvent, is recycled to the coal liquefaction unit for producing said coal liquefied oil.
3. The process according to Aspect 1, characterized in that a high pressure separator is independently used to conduct said separation in

each of the steps (1), (2) and (3), and the hydrogen-enriched gas separated from each of the individual high pressure separator is recycled to the corresponding hydrogenation reactor of each step,
4. The process according to Aspect 1, characterized in that the hydro-stabilizing reactor is a fixed bed reactor or an expanded bed reactor.
5. The process according to Aspect 1, characterized in that the coal liquefied oil has a distillation range of C5-520C.
6. The process according to Aspect 1, characterized in that the hydro- stabilizing catalyst in step (1) is a catalyst, containing no halogen atoms, wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous alumina or/and a silica-alumina, wherein the Group VIB metal is selected from Mo or/and W, and the Group VIII non- noble metal is selected from Co or/and Ni.
7. The process according to Aspect 1, characterized in that the hydro- stabilizing reaction in step (1) is conducted at a hydrogen partial pressure of 4.0-20.0 MPa, a reaction temperature of 280-450C, a liquid hourly space velocity of 0.1-10 h”1 and a hydrogen/oil ratio of 300-2800 Nm/m3.
8. The process according to Aspect 1, characterized in that the hydro- upgrading catalyst in step (2) is a catalyst, containing a molecular sieve, wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous alumina or/and a silica-alumina, wherein the Group VIB metal is selected from Mo or/and W, and the Group VIII non- noble metal is selected from Co or/and Ni.
9. The process according to Aspect 1, characterized in that the hydro- upgrading reaction in step (2) is conducted at a hydrogen partial pressure of 6.0-20.0 MPa, a reaction temperature of 280-450°C, a liquid hourly space velocity of 0.1-20 h-1 and a hydrogen/oil ratio of 400-3000 Nm/m3.
10. The process according to Aspect 1, characterized in that the hydrocracking reaction in step (3) is conducted in a single-stage and single-catalyst mode, wherein the hydrocracking catalyst used is a catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous silica-alumina or an amorphous silica- magnesia, wherein the Group VIB metal is selected from Mo or/and W, and the Group VIII non-noble metal is selected from Co or/and Ni.

11. The process according to Aspect 1, characterized in that the hydro cracking reaction in step (3) is conducted in a single-stage and double-catalysts mode, wherein the hydrorefining catalyst is filled before the hydrocracking catalyst, the hydrorefining catalyst is a catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous alumina or/and a silica-alumina, wherein the Group VIB metal is selected from Mo or/and W, and the Group VIII non-noble metal is selected from Co or/and Ni; and the hydrocracking catalyst is a catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on a Zeolite Y, wherein the Group VIB metal is selected from Mo or/and W, and the Group VIII non-noble metal is selected from Co or/and Ni;
12. The process according to Aspect 1, characterized in that the hydrocracking reaction in step (3) is conducted at a hydrogen partial pressure of 4.0-20.0 MPa, a reaction temperature of 280-450 C, a liquid hourly space velocity of 0.1-20 h-1 and a hydrogen/oil ratio of 300-2000 Nm3/m3.
Description of Drawings
Fig. 1 outlines the diagram of the combined process for converting the
coal liquefied oil with a maximum yield according to the present
invention.
Detailed Description of the Invention
The process of the present invention comprises hydro-stabilizing of a coal liquefied oil, hydro-upgrading of a diesel fraction I from the hydro-stabilizing, and hydrocracking of an unconverted oil fraction from the hydro-stabilizing, and the flow chart of each portion is described as follows,
(I) hydro-stabilizing of the coal liquefied oil
Hydrorefining method is used to saturate olefins and remove heteroatoms such as oxygen, nitrogen and the like, so as to increase the stability of the coal liquefied oil as the main object. Accordingly, the method is usually called as the process for hydro-stabilizing.

After filtration by a filtering device, the coal liquefied oil produced in a coal liquefaction unit is mixed with hydrogen, and heated to a required reaction temperature, and fed into a hydro-stabilizing reactor. The effluent from the hydro-stabilizing reactor primarily comprises H2, light hydrocarbons, H2S, NH3, water and hydro-stabilized oils. The effluent from the hydro-stabilizing reactor is fed in sequence into a high pressure separator, a low pressure separator and a distillation tower. Through the separation system and fractionation system are separated a gas (including a hydrogen-enriched gas separated from the high pressure separator, and light hydrocarbons), a naphtha fraction (including a light and a heavy naphtha fraction), a diesel fraction I and an unconverted oil fraction, wherein the diesel fraction I obtained thereby is fed into a hydro-upgrading unit, a part or all of the unconverted oil fraction obtained thereby is fed into a hydrocracking unit. In another embodiment, a part of the unconverted oil fraction is recycled as a hydrogen donor solvent to said coal liquefaction unit. In another embodiment, said hydrogen-enriched gas is mixed with fresh hydrogen, and then sent to the hydro-stabilizing reactor.
(II) hydro-upgrading of the diesel fraction I from the hydro-stabilizing unit
The diesel fraction I produced in the hydro-stabilizing unit is fed into the hydro-upgrading unit, so as to increase the cetane number of the diesel. The hydro-upgrading unit has a similar process flow to the hydro-stabilizing unit, i.e., mixing the diesel fraction from the hydrostabilized products with hydrogen, and conducting reactions in the hydro-upgrading reactor. The effluent from the hydro-upgrading reactor is fed in sequence into a high pressure separator, a low pressure separator and a distillation tower. Through the separation system and fractionation system are separated a gas (including a hydrogen-enriched gas separated from the high pressure separator, and light hydrocarbons), a naphtha fraction (including a light and a heavy naphtha fraction) and a diesel fraction II. In another embodiment, said hydrogen-enriched gas is mixed with fresh hydrogen, and then sent to the hydro-upgrading reactor.

(III) hydrocracking of the unconverted oil fraction from the hydro-stabilizing unit
The unconverted oil fraction produced in the hydro-stabilizing unit is sent to the hydrocracking unit.
Under the circumstance that an amorphous hydrocracking catalyst is used in the hydrocracking unit, the process flow thereof is similar to those of the aforesaid two hydrogenation, except for setting up a hydrocracking reactor therein (operated in a single-stage and single-catalyst mode). The unconverted oil fraction from the hydro-stabilizing unit is mixed with hydrogen, and reactions is conducted in the hydrocracking reactor. The effluent from the hydrocracking reactor is fed in sequence into a high pressure separator, a low pressure separator and a distillation tower. Through the separation system and fractionation system are separated a gas (including a hydrogen-enriched gas separated from the high pressure separator, and light hydrocarbons), a naphtha fraction (including a light and a heavy naphtha fraction) and a diesel fraction III. In another embodiment, said hydrogen-enriched gas is mixed with fresh hydrogen, and then sent to the hydrocracking reactor.
Under the circumstance that a molecular sieve type catalyst having a good diesel fraction selectivity is used in the hydrocracking process, a hydrorefining reactor and a hydrocracking reactor (operated in a single-stage and double-catalyst mode) are set up in the process flow. At this time, the hydro-stabilized unconverted oil fraction is mixed with hydrogen, and fed into the hydrorefining reactor. The effluent from the hydrorefining reactor primarily comprises H2S, NH3 and hydro-refined oils. Without a gas-liquid separation, the effluent from the hydrorefining reactor is directly fed into the hydrocracking reactor, in which ring-opening, chain-breaking and hydro-saturating reactions occur. The effluent from the hydrocracking reactor primarily comprises H2, light hydrocarbons, H2S, NH3 and hydrocracked product oils. Said effluent is fed in sequence into a high pressure separator, a low pressure separator and a distillation tower. Through the separation system and fractionation system are separated a gas (including a hydrogen-enriched

gas separated from the high pressure separator, and light hydrocarbons), a naphtha fraction (including a light and a heavy naphtha fraction) and a diesel fraction III.
Under the circumstance that the hydrocracking process is performed in a recycle mode, an unconverted oil fraction is further separated from the distillation tower, and then recycled to the inlet of the hydrocracking reactor.
Both the diesel fractions II and III are the diesel products of the present invention, and they may be used together.
There is no particular limitation for the distillation range of the coal liquefied oil feedstock used in the present invention. Generally, it is C5-520˚C:, preferably C5-480˚C (ASTM D-1160). The heavier the fraction is, the higher the content of the impurities such as metals and asphaltenes, and the worse the effects on the of the hydrogenate catalyst life is. Nitrogen content in the feedstock is usually not more than 1.2 % by weight, preferably not more than 0.8 % by weight, and sulphur content therein is usually not more than 2.0 % by weight. In the process of the present invention, the hydro-stabilizing reaction in the hydro-stabilizing reactor is conducted at a hydrogen partial pressure of 4.0-20.0 MPa, a reaction temperature of 280-450˚C, a liquid hourly space velocity of 0.1-10 h-1 and a hydrogen/oil ratio of 300-2800 Mm3/m3.
The hydro-upgrading reaction in the hydro-upgrading reactor is conducted at a hydrogen partial pressure of 6.0-20.0 MPa, a reaction temperature of 280-450˚C:, a liquid hourly space velocity of 0.1-20 h-1 and a hydrogen/oil ratio of 400-3000 Mm3/m3.
The hydrocracking reaction in the hydrocracking reactor (including the single-stage and single-catalyst mode, and the single-stage and double-catalysts mode) of the present invention is conducted at a hydrogen partial pressure of 4.0-20.0 MPa, a reaction temperature of 280-450˚C, liquid hourly space velocity of 0.1-20 h’1 and a hydrogen/oil ratio of 500-2000 Mm3/m3.
There is no particular limitation for the hydro-stabilizing catalyst used therein. A catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous alumina or/and a silica-

alumina, which contains no halogen atoms, may be used. Such a catalyst has a very strong hydrodenitrogenation activity. In addition, said Group VIB metal is not specially limited, but is preferably Mo or/and W; and said Group VIII non-noble metal is not specially limited, but is preferably Co or/and Ni. Due to a certain amount of metals and asphaltenes in the coal liquefied oil, a suitable amount of hydrogenation guard catalysts may be filled from the top of the hydro-stabilizing catalyst. The amount filled is determined by the impurity content in the coal liquefied oil and the operation period of the unit, which is known for those skilled in the art. Generally, the volume ratio of said hydrogenation guard catalyst to said hydro-stabilizing catalyst is from 0.03 to 0.35.
The hydro-upgrading catalyst used therein may be a catalyst, containing a molecular sieve, wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous alumina or/and a silica-alumina, wherein the Group VIB metal is not particularly limited, but is preferably Mo or/and W, and the Group VIII non-noble metal is not particularly limited, but is preferably Co or/and Ni. The hydrocracking process may be operated in a single-stage and single-catalyst mode, or in a single-stage and double-catalysts mode. When a single-stage and single-catalyst mode is used, the hydrocracking catalyst may be a catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous silica-alumina or an amorphous silica-magnesia or other modified alumina, wherein the Group VIB metal is not particularly limited, but is preferably Mo or/and W, and the Group VIII non-noble metal is not particularly limited, but is preferably Co or/and Ni. When a single-stage and double-catalysts mode is used, a hydrorefining catalyst is filled prior to the hydrocracking catalyst. The hydrorefining catalyst may be a catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on an amorphous alumina or a silica-alumina, wherein the Group VIB metal is not particularly limited, but is preferably Mo or/and W, and the Group VIII non-noble metal is not particularly limited, but is preferably Co or/and Ni. In addition, the hydrocracking catalyst may be a catalyst wherein a Group VIB metal or/and a Group VIII non-noble metal is/are supported on a Zeolite Y, wherein the Group VIB metal is not

particularly limited, but is preferably Mo or/and W, and the Group VIII non-noble metal is not particularly limited, but is preferably Co or/and Ni. In the present invention, a hydro-upgrading unit and a hydrocracking unit are used respectively for processing the diesel fraction I and the unconverted oil fraction from the hydrostabilized product. The hydro-upgrading unit is used for processing the diesel fraction I from the hydrostabilized product, so as to reduce the aromatics content, and achieve the object of reducing the diesel fraction density and greatly increasing the cetane number of the diesel fraction by moderate degree of ring-opening. The yield of the diesel fraction II obtained thereby can reach 95 % by weight or above. In addition, the hydrocracking unit is used for processing the unconverted oil fraction, so as to convert the relatively heavy fraction into a naphtha fraction, and a diesel fraction HI having a low content of impurities such as sulphur and nitrogen and having a high cetane number. Both the diesel fractions II and III are the diesel products of the present invention, and they can be used together. If the aforesaid processing routine is used, diesel products are produced from the coal liquefied oil in a high yield, and the sulphur, nitrogen and aromatics content thereof may satisfy the standard of Category III oils under “Worldwide Fuels Charter”. In addition, the product has a cetane number of higher than 45.
Preferably, the catalyst used for the hydro-upgrading has a well balanced hydrogenating activity and ring-opening cracking activity. It, thereby, is suitable for processing aromatics having two rings or more, and increasing the cetane number thereof by ring-opening. It is know that an aromatics hydrosaturation precedes a ring-opening reaction. Therefore, firstly, said catalyst should have a good hydrorefining properties, i.e., saturating properties, so as to provide the cracking reaction with reactants that a ring-opening reaction is easily to occur therewith. Then, in addition to the saturating property, the catalyst should show a selectivity with respect to a ring-opening and cracking reaction and be capable to disturb the balance in a hydro-saturating reaction, so as to achieve the object of changing the structures of hydrocarbons and increasing the cetane number thereof. The cracking function of a catalyst contributes to its acidic components, which are

easily subject to poisons (for example, nitrides) and then deactivated. High nitrogen content is another feature of the diesel from a coal liquefied oil. In order to reduce the effects brought by the high nitrogen content, a relatively high hydrocracking activity is needed for the catalyst. Finally, the hydrogenating activity of the catalyst must match with its cracking activity. If there are a low hydrogenating activity and a high cracking activity, aromatics cannot be well saturated. Accordingly, reactants for use with the ring-open reaction cannot be obtained in a large amount, easily rendering cracking of “useful” hydrocarbons such as linear paraffins, producing of smaller molecules, and decreasing of the yield of the diesel. If there are a high hydrogenating activity and a low cracking activity, the hydrosaturating reaction proceeds to a deepened degree so that the aromatics are completely hydrogenated, while the ring-opening reaction goes forward insufficient, which will increase the hydrogen consumption, whereas the cetane number is not greatly increased.
The hydrocracking unit may be operated in a one-pass mode, or a recycle mode. The hydrocracking unit may use an amorphous hydrocracking catalyst, and be operated in a single-stage and single-catalyst mode. It may also use a molecular sieve type catalyst having a good diesel fraction selectivity, and be operated in a single-stage and double-catalysts mode. In the hydrogenation process of the coal liquefied oil, the unit is used to convert the unconverted oil fraction into a light oil fraction and produce no a further unconverted oil fraction, so as to convert, to a maximum extent, the coal liquefied oil into a light oil fraction and produce a diesel product from the coal liquefied oil as much as possible.
Since the coal liquefied oil contains a great amount of aromatics and nitrogen, it is very difficult to refine them with conventional processes. The feature of the present process lies in a reasonable combination of the hydro-stabilizing unit, the hydro-upgrading unit and the hydrocracking unit. In the present invention, difficulties that may occur in the processing are will distributed across the process, resulting in an optimized unit performance. For example, if the properties of the feedstock for the hydro-stabilizing become worse, the optimized unii

performance can be maintained by increasing the severity of the hydro-stabilizing and the hydrocracking to an acceptable level. Moreover, by suitably adjusting the cut point between the diesel fraction I and the unconverted oil fraction from the hydro-stabilizing unit, the content of impurities in the diesel fraction I can be kept at a stable level, so as to maintain the stability of the operating conditions of the hydro-upgrading unit.
The process of the present invention is further explained by referring to the drawing, but is not used to limit the present invention. The accompanying drawing, which is included to provide a further understanding of the invention and is incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.
Fig. 1 shows the diagram of the combined process for converting the coal liquefied oil with a maximum yield according to the present invention. Many essential equipments, such as pumps, air coolers and valves, are omitted from Fig. 1.
The invention is described more fully hereinafter with reference to the accompanying drawing, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art.
The flow chart of the process is detailed as follows. A coal liquefied oil is fed into filter 3 via pipeline 1 and filtrated. After the pressure is increased to a required reaction pressure by a feedstock pump, it is then mixed with hydrogen from pipeline 6, heat-exchanged with a heat exchanger 4, heated via a heating furnace 7, and fed into a hydro-stabilizing reactor 9. The thus obtained mixture contacts with a hydrogenation guard catalyst bed and a hydro-stabilizing catalyst bed to remove metals and impurities from the oil feedstock, such as sulphur, nitrogen and the like. Cold hydrogen needs to be introduced into the middle of the reactor to control the reaction temperature since a

hydrorefining reaction is a strong exothermic one. The effluent from the hydro-stabilizing reactor 9 is fed via pipeline 8 into the heat-exchanger 4 for heat-exchanging, and then fed into a high pressure separator 10 in which it is divided into two streams, wherein one of them is a hydrogen-enriched gas comprising hydrogen as a main component, and some hydrogen sulfide and ammonia. Said hydrogen-enriched gas is compressed via a recycle compressor, and mixed via pipeline 5 with fresh hydrogen from pipeline 2, and then recycled to the reactor 9 via pipeline 6. The other stream is fed into a low pressure separator 12 via pipeline H to further remove light hydrocarbons. The light hydrocarbons are discharged from the unit via pipeline 13. The effluent from the bottom of the low pressure separator 12 is fed via pipeline 14 into a distillation tower 15 to obtain a naphtha fraction, a diesel fraction I and an unconverted oil fraction, wherein the naphtha fraction is discharged from the unit via pipeline 16, and the diesel fraction I and the unconverted oil fraction are fed into a hydro-upgrading unit and a hydrocracking unit respectively via pipelines 17 and 18. The diesel fraction I is fed into a buffer tank 19 via pipeline 17. After the pressure is increased to a required reaction pressure by a feedstock pump, it is then mixed with hydrogen from pipeline 20, heat-exchanged with a heat exchanger 21, fed via pipeline 22 into a heating furnace 23, and then fed into a hydro-upgrading reactor 24. The thus obtained mixture contacts with a hydro-upgrading catalyst bed to further remove impurities, such as sulphur, nitrogen and the like, saturate aromatics therein, and conduct a ring-opening reaction to some extent. Although the ring-opening reaction is an endothermic one, the reaction as a whole is still an exothermic one since the hydrorefining reaction is a strong exothermic one. Cold hydrogen needs to be introduced into the middle of the reactor to control the reaction temperature. The effluent from the hydro-upgrading reactor 24 is fed via pipeline 25 into the heat-exchanger 21 for heat-exchanging, and then fed into a high pressure separator 26 in which it is divided into two streams, wherein one of them is a hydrogen-enriched gas comprising hydrogen as a main component, and some hydrogen sulfide, ammonia and light hydrocarbons produced by the cracking. Said hydrogen-enriched gas is

compressed via a recycle compressor, and mixed via pipeline 27 with fresh hydrogen from pipeline 2, and then recycled to the reactor 24 via pipeline 20. The other stream is fed into a low pressure separator 29 via pipeline 28 to further remove light hydrocarbons. The light hydrocarbons are discharged from the unit via pipeline 30. The effluent from the bottom of the low pressure separator 29 is fed via pipeline 31 into a distillation tower 32, and the naphtha fraction and the diesel fraction II fractionated therein are drawn out of the unit respectively via pipelines 33 and 34.
If the hydrocracking is in a single-stage and double-catalysts mode, the hydrostabilized unconverted oil fraction is fed into a buffer tank 35 via pipeline 17. After the pressure is increased to a required reaction pressure by a feedstock pump, it is then mixed with hydrogen from pipeline 36, heat-exchanged via a heat exchanger 37, heated via a heating furnace 39, and then fed into a hydrorefining reactor 40. The thus obtained mixture contacts with a hydrorefining catalyst bed to remove impurities, such as sulphur, nitrogen and the like, partly saturate aromatics therein, and crack the heavy fractions to a less degree. Since hydrorefining reaction is a strong exothermic one, cold hydrogen needs to be introduced into the middle of the reactor to control the reaction temperature. The effluent from the hydrorefining reactor 40 is fed via pipeline 41 into a hydrocracking reactor 42 to crack the heavy components into a desired light product by contacting with a hydrocracking catalyst. As with the hydrorefining, cold hydrogen needs to be introduced into the hydrocracking reaction so as to prevent the reaction temperature from increasing to an undesired degree since it is an exothermic reaction. The effluent from the hydrocracking reactor 42 is fed via pipeline 43 into a heat exchanger 37 for heat exchanging, and then fed into a high pressure reactor 44 in which it is divided into two streams, wherein one of them is a hydrogen-enriched gas comprising hydrogen as a main component, and some hydrogen sulfide, ammonia and light hydrocarbons produced by the cracking. Said hydrogen-enriched gas is compressed via a recycle compressor, and mixed via pipeline 45 with fresh hydrogen from pipeline 2, and then recycled to the reactor 40 via pipeline 36. The other stream is fed into a

low pressure separator 47 via pipeline 46 to further remove light hydrocarbons. The light hydrocarbons are discharged from the unit via pipeline 49. The effluent from the bottom of the low pressure separator 47 is fed via pipeline 48 into a distillation tower 50, and the naphtha fraction and the diesel fraction III fractionated therein are drawn out of the unit respectively via pipelines 51 and 52.
If the hydrocracking is a recycle process, a further unconverted oil fraction will be fractionated from the fractionating system 50. The unconverted oil fraction is recycled via pipeline 53 to the hydrocracking reactor 42 for further hydrocracking.
If the hydrocracking is a single-stage and single-catalyst process without the hydrorefining reactor 40, the unconverted oil fraction feedstock from the hydro-stabilizing unit passes in sequence through pipeline 17, buffer tank 35, heat exchanger 37, and heating furnace 39, and then is fed into the hydrocracking reactor 42.
Although the hydro-stabilizing reactor is described above using a fixed bed reactor as an example, said hydro-stabilizing reactor may be an expanded bed reactor in another optional embodiment The expanded bed reactor has the following features:
(1) The oil feedstock and hydrogen are fed from the bottom of the reactor, and the reaction product is discharged from the top thereof, i.e., feeding the feedstock from the bottom and discharging the product from the top. The feedstock distributing plate of the reactor is located at the bottom of the reactor. Generally, a porous structure is used to realize a uniform distribution of the feedstock.
(2) The catalyst bed has an expansion volume ratio of not more than 5%.
(3) There is no mass recycle in said expanded bed reactor, unnecessary for an external recycle pump and for an in-line replacement of the catalyst.
When an expanded bed reactor is used, the coal liquefied oil after filtration is fed together with hydrogen from the bottom of the reactor into the reactor to hydro-stabilize the coal liquefied oil. In the present invention, the coal liquefied oil feedstock can be hydro-stabilized by using an in-line or off-line method. When an in-line

method is used, a part of the unconverted oil fraction from the hydro-stabilizing is recycled as a hydrogen donor agent back to the coal liquefaction unit for producing the coal liquefied oil feedstock. The process of the present invention can be used for the production of a high quality diesel from a coal liquefied oil. Based on the diesel fraction I and the unconverted oil fraction obtained from the hydro-stabilizing unit, the total yield of the diesel product (sum of the diesel fractions II and III) is more than 92 % by weight. Moreover, said product has an extremely low sulphur and nitrogen content, a relatively low aromatics content, a relatively low density and a cetane number of higher than 45. Accordingly, said product meets the requirements on sulphur, nitrogen and aromatics content with respect to the Category III diesel under the “Worldwide Fuels Charter”.
Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention.
Example
The following example is used to further disclose the process, but is not used to limit the invention.
Both of the coal liquefied oil feedstock A and B in the Examples are filtered, and the properties thereof are listed in Table 1. In addition, the hydrogenation guard catalyst, the hydro-stabilizing catalyst, the hydro-upgrading catalyst, the hydrorefining catalyst and the hydrocracking catalyst used therein are all produced by the Sinopec Changling Catalyst Factory, and the experiment was conducted on a pilot plant-scale fixed bed hydrogenation unit.
The density of the coal liquefied oil feedstock, the unconverted oil fraction and the diesel fraction is determined by a hydrometer method, and under the Chinese national standard of GB/T 1884-92 (equivalent to ASTM D4052-95).
The sulphur content in the coal liquefied oil feedstock is determined by an energy-dispersive X-ray fluorescence spectrometry, and under the Chinese national standard of GB/T 17040-1997 (equivalent to ASTM

D4294-90).
The nitrogen content in the coal liquefied oil feedstock is determined by a chemiluminescent method, and under the Chinese standard of SH/T 0704-2001 (equivalent to ASTM D5762-98).
The total aromatics content and the polycyclic aromatics content in the coal liquefied oil feedstock and the unconverted oil fraction are determined by a mass spectrography, and under the Chinese standard of RIPP 160-90 (equivalent to ASTM D3239).
The total aromatics content and the polycyclic aromatics content in the diesel fraction are determined by a mass spectrography, and under the Chinese standard of SH/T 0606-94 (equivalent to ASTM D2425).
The distillation range of the coal liquefied oil feedstock and the unconverted oil fraction is determined by a vacuum distillation method, and under the Chinese national standard of GB/T 9168-1997 (equivalent to ASTM Dl 160-95).
The hydrogen content in the unconverted oil fraction is determined by an element analyzer, and under the Chinese standard of SH/T 0656-1998 (equivalent to ASTM D5291-01).
The distillation range of the diesel fraction is determined by a distillation method for petroleum products, and under the Chinese national standard of GB/T 6536-1997 (equivalent to ASTM D86-95).
The sulphur content of the diesel fraction is determined by a microcoulometric method, and under the Chinese standard of SH/T 0253-92 (equivalent to ASTM D3120-82).
The nitrogen content of the diesel fraction is determined by a chemiluminescent method, and under the Chinese standard of SH/T 0657-1998 (equivalent to ASTM D4629-86).
The cetane number of the diesel fraction is determined by using a method for determining the igniting property of a diesel, and under the Chinese national standard of GB/T 386-91 (equivalent to ASTM D613- 86).
Example 1
The experimental feedstock is the coal liquefied oil A; the hydrogenating guard catalyst is RG10-A and RG10-B, and the hydro-

stabilizing catalyst is RJW-2. The hydro-upgrading catalyst for the hydro-upgrading is RIC-1; the hydrocracking is performed in a single-stage and double-catalysts mode and by a one-pass process; the hydrorefining catalyst is RN-10, the hydrocracking catalyst is RT-5. The hydro-stabilizing reaction conditions and the properties of the unconverted oil fraction can be found in Table 2, and the hydro-upgrading and hydrocracking reaction conditions and the properties of the diesel fraction can be found in Table 3.
It can be seen from the tables that the density of the coal liquefied oil is at an acceptable level, and the hydro-upgrading conditions are relatively moderate. The unconverted oil fraction in the hydrostabilized product is a suitable hydrogen donor solvent. The diesel fractions from the hydro-upgrading unit and the hydrocracking unit have a very low nitrogen and sulphur content and a relatively low aromatics content, and meets the requirements with respect to the Category III diesel under the “Worldwide Fuels Charter”. The cetane number thereof goes beyond 45, which shows that it is a qualified diesel product. In addition, the diesel fraction from the hydro-upgrading unit has a yield of more than 95 % by weight, and the diesel fraction from the hydrocracking unit has a yield of more than 90% by weight, which both achieve the object of converting a coal liquefied oil into the diesel as much as possible.
Example 2
The experimental feedstock is the coal liquefied oil B; the hydrogenating guard catalyst is RG10-A and RG10-B, and the hydro-stabilizing catalyst is RJW-2. The hydro-upgrading catalyst for the hydro-upgrading is RIC-1; the hydrocracking is performed in a single-stage and double-catalysts mode and by a one-pass process; the hydrorefining catalyst is RN-10, the hydrocracking catalyst is RT-5. The hydro-stabilizing reaction conditions and the properties of the unconverted oil fraction can be found in Table 2, and the hydro-upgrading and hydrocracking reaction conditions and the properties of the diesel fraction can be found in Table 3.
It can be seen from the tables that the density of the coal liquefied oil is

close to 1, and the hydro-upgrading conditions are relatively moderate. The unconverted oil fraction from the hydro-stabilizing is a suitable hydrogen donor solvent. The diesel fractions from the hydro-upgrading unit and the hydrocracking unit have a very low nitrogen and sulphur content and a relatively low aromatics content, and meets the requirements with respect to the Category III diesel under the “Worldwide Fuels Charter”. The cetane number thereof goes beyond 45, which shows that it is a qualified diesel product. In addition, the diesel fraction from the hydro-upgrading unit has a yield of more than 95 % by weight, and the diesel fraction from the hydrocracking unit has a yield of more than 88 % by weight.
It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

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Patent Number

268682

Indian Patent Application Number

1232/CHE/2006

PG Journal Number

37/2015

Publication Date

11-Sep-2015

Grant Date

11-Sep-2015

Date of Filing

14-Jul-2006

Name of Patentee

CHINA PETROLEUM & CHEMICAL CORPORATION

Applicant Address

6A, HUIXIN DONG STREET,CHAOYANG DISTRICT, BEIJING 100029. CHINA

Inventors:

#	Inventor's Name	Inventor's Address
1	HU, ZHIHAI	18, XUEYUAN ROAD, HAIDIAN DISTRICT,BEIJING 100083., CHINA
2	JIANG, DONGHONG	18, XUEYUAN ROAD, HAIDIAN DISTRICT,BEIJING 100083.
3	XIONG, ZHENLIN	18, XUEYUAN ROAD, HAIDIAN DISTRICT,BEIJING 100083.
4	DONG, JIANWEI	18, XUEYUAN ROAD, HAIDIAN DISTRICT,BEIJING 100083.
5	NIE, HONG	18, XUEYUAN ROAD, HAIDIAN DISTRICT,BEIJING 100083.
6	WANG, JINYE	18, XUEYUAN ROAD, HAIDIAN DISTRICT,BEIJING 100083.

PCT International Classification Number

C10G01/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	200510083899.9	2005-07-15	China