Title of Invention

"AN IMPROVED PROCESS FOR THE PREPARATION OF GROUP II / GROUP III LUBRICATING OIL"

Abstract

This invention provides a process for the preparation of group ll/group III base oils of saturated hydrocarbon components having very high viscosity index and very low sulphur content, from conventionally refined lube base stocks through adsorption over a fixed bed of adsorbents silica gel and alumina of defined grades at ambient temperature and pressure conditions. This is an alternate route to hydrocracking/ hydro processing, as they are comparable in their properties and compositional features to new generation base oils meeting all the API specifications.

Full Text

This invention relates to an improved process for the preparation of group II / group III lubricating oil. This invention particularly relates to a process for the preparation of group ll/group III base oils of saturated hydrocarbon components, very high viscosity index and very low sulphur content, from conventionally refined lube base stocks through adsorption over a fixed bed of adsorbents silica gel and alumina of defined grades at ambient temperature and pressure conditions as an alternate route to hydrocracking/ hydro processing, as they are comparable in their properties and compositional features to new generation base oils meeting all the API specifications. The present invention relates to an alternate process for producing new generation lubricating base oils. More particularly this invention relates to a new process for producing Group II / Group III base oils just by introducing one additional step of adsorption over a fixed bed of adsorbents at ambient temperature and pressure to transform conventionally refined mineral base oils into group II / group III base oils as per API classification of 1996. Less fundamental but more imminent are changes in the composition of mineral oil base stocks for motor oil being made by the latest developments in refining. Conceptually two types of refining processes are used to make lubricating oil base stocks either separation based or chemical conversion. In the separation process, desirable components of crude oil are selected by vacuum distillation, solvent extraction and solvent dewaxing while in chemical conversion process , certain desirable parts of he crude oil are chemically transformed into useful lubricating oil base stock components. The products from chemical transformation process form a background for the development of a new class of lubricating base oils. Whatever process route is followed, the main objective is to economically optimise the ratio of desirable components to the undesirables as per the product performance requirements. These new generation lubricating oil base stocks (group II & III) are required to provide a technological answer to performance and value not currently provided by solvent refined (group I) lubricating oil base stocks. The basis of this new generation highly refined all paraffin base oils is that they are almost free of reactive hydrocarbons and other impurities that contribute to the degradation of conventionally refined lubricating oil base stocks in service. The key to these water white base oils purity is the conversion process, which chemically removes practically all reactive hydrocarbons from a wide range of crude oils, including high sulfur / sour crudes. These products are referred to as the unconventional base oils and are expected to exceed the performance of conventionally refined lubricants in oxidation stability, low carbon forming tendency, low volatility, viscosity stability and response to additives. This reduced level of reactive hydrocarbons in these base oils allows them to act as a better carrier for the additive package used to make the finished product, minimising unwanted reactions between base oil components and additives which can interfere with the additives performance. The new generation base oils have been divided into four classes or groups by the American Petroleum Institute along with a group I which represents the base stock used in the bulk of existing motor oils meeting the ILSAC (International Lubrication Standardization Advisory Committee) minimum performance standard for passenger car (petrol) engines GF-1 and API SH qualities. Group I Mainly solvent refined conventionally base stocks containing less than 90% saturates (paraffinic hydrocarbons) and or more that 0.03% sulphur. The Viscosity Index will be between 80 to 120. Group 2 Mainly hydrocracked and catalytically dewaxed base stocks containing 90% or more saturates, 0.03% or less sulphur and a Viscosity Index between 80 and 120. Group 3 Hydroisomerised wax products with a Viscosity Index of 120 or greater and other characteristics asof group II. Group 4 Includes polyalphaolefin synthetic hydrocarbon base stocks. Group 5 All other types of base stocks, not included above. Demand for higher quality lubricants and the push for more stringent specifications for several products are creating a need for new generation of base stocks that have higher performance than current conventional base oils. This along with environmental considerations have led to subsequent developmental changes regarding lubricant manufacturing technology. Even then the expected low volatility requirements for the upcoming GF-3 passenger car motor oil (PCMO) cannot be met by most conventional base stocks, especially when combined with requirements for lower emissions and higher fuel economy. Similarly, there are movements afoot within the ranks of many auto and equipment manufacturers for engine oils with extended drain intervals and "fill for life" automatic transmission fluids (ATF) that would last the life of a vehicle. The higher viscosity index petroleum base stocks are produced by severe hydrocracking processes. The chemical reactions it promotes cause significant reductions in viscosities and yields. Also product reformulation are often required when switching from solvent refined to hydroprocessed lubricating oil base stocks. Directionally the industry trend is expected to be hydrocracking/hydrotreating rather than solvent refining. Another way of producing new generation base stocks is wax hydroisomerisation which gives products of exceptionally high viscosity index. However, where capital constraints exist and high viscosity base stocks are needed, solvent refining is a viable choice. These hydroprocessing routes require hydrogen and are economically value for large capacity plants only. The process also requires special metallurgy for equipments fabrication operates at high pressure and reasonably high temperature, but it provides good flexibility with respect to the feed stock. The route is also energy intensive and requires high investment. In contrast to the hydroprocessing routes, the present invention operates at ambient temperature and pressure conditions using less expensive solvents and yields products of comparable qualities and compositional features. In view of these, it is worth to exploit the idea to have low levels of reactive species as achieved by hydroprocessing technologies in group II/group III oils. This provides some chemical inertness to the base oils towards additives. So we thought to remove those reactive hydrocarbons through adsorptive separation route. The object of the present invention is to provide a simple process for making lubricating oil base stocks comparable in properties to new generation base oils. In this process the conditions described in the prior art are not required as the separation occurs at ambient temperature and pressure conditions thus the requirements like hydrogen, temperature and pressure are eliminated. Another object of the present invention is to provide a process for making new generation base oils in which the used solvents are recovered and the adsorbents are regenerated for further use. Still another object of the present invention is to provide a process by which the base oils produced are of comparable/better quality to the new generation base oils available. Yet another object of the present invention is to provide a process which is very simple, energy efficient and meets the stringent requirement of very low sulfur content. Further the object of the present invention is to provide a process which is economical in their operation as it could be a batch or a continuous process as compared to the hydroprocessing routes which are economical only at large scale. Accordingly the present invention provides, an improved process for the preparation of group II / group III lubricant base oils which comprises charging of conventional base oils for adsorption over a organic solvent mediated pre-weted fixed bed of adsorbents column of silica gel / alumina , at an optimal feed to adsorbent ratio ( 1:10 to 1:18), at room temperature (25°C to 35°C) and pressure (atmospheric pressure), diluting the feed using organic solvent such as herein described , eluting by dry compressed air / nitrogen, adding an aliphatic alcohol to the said eluant to desorb the adsorbed material, collecting the resultant to get group ll/group III lubricant base oils. According to embodiment of the invention, the process operates at ambient temperature and pressure conditions, the feed to adsorbent ratio is maintained at 1 : 10to1: 16. In an embodiment of the present invention, organic solvent used for prewetting, dilution / elution is selected from pentane, hexane, cyclohexane. In other embodiment of the invention, dry compressed air / nitrogen is required optionally during the processing of heavy feeds so as to adjust / increase the elution rate. In another embodiment of the present invention, organic solvent used to desorb the adsorbed material is selected from menthanol, ethanol, isopropanol. In other embodiment of the invention, feeds ranging from light to inter or heavy neutrals may be processed as is the viscosity range targeted for the end use applications. In yet another embodiment of this invention, the feed required to be processed through this route is available easily as it is a routine production in our country. Accordingly the present invention provides a novel approach for the production of of high quality base oils through a very common adsorptive separation route which are comparable to new generation base oils produced through hydroprocessing route available in the market making use of conventional solvent refined base oils,. The process according to this invention will now be described in details with respect to specific quantitative values. To carry out the present process in practical an elongated glass column is used with the proper arrangement of feed inlet and out let for various fractions. The size of the glass column varies (250 x 3 to 250 x 4 cm). This process is based on batch mode. In this process, first the packing of the column is done using silica gel / alumina adsorbents in an optimised feed to adsorbent ratio (1:10 to 1:16). Then prewetting is done using normal hexane. Feed is diluted around ten times with the prewetting solvent and charged to the column after which elution proceeds at an appropriate rate. Whole process operate at room temperature. Further solvent is added when the feed reached the top of the silica gel bed. After reaching the level to the top of the silica gel, selected solvent is added to desorb the adsorbed material. Through this preferential adsorption, the aromatic hydrocarbons are removed from the feed to the maximum extent. To increase the elution rate with any particular feed stock, dry compressed air/dry nitrogen is put through the column. This helps in desorbing the adsorbed material from the adsorbents by adjusting / increasing the elution rate. The eluant collected in a number of fractions are made solvent free by appropriate procedures and the solvent free hydrocarbon fractions are made into two major portions one is aromatic free and other is aromatic rich. The degree of separation is thereafter confirmed by refractive index and ultra violet spectroscopy following standard procedures. A scientific explanation for this invention may be given as : Adsorptive separation exhibits much higher mass transfer efficiency than any conventional extraction or extractive distillation as the other two alternate approaches. Such high mass transfer efficiency stems from the use of small particles of adsorbent with high interfacial area and the absence of significant axial mixing. The nature, utility and further features of this invention will be more clearly apparent from the following detailed description beginning with a consideration of general aspects and features of the invention and concluding with some specific examples. Group I base oils are fast moving towards aging and losing their leading position as compared to group II and group III base oils. This invention upgrades this weak position into more high value favorable leading position as a move towards mature position. These new generation group II/group III base oils are produced via hydro processing today. But it must be recognized that around 85-90% of the worldwide base oil production uses solvent refining rather than hydrocracking. Since our country at the moment do not have the facility of hydrocracked base oil production, we have deviced our own strategy to convert the conventionally refined base oils into new generation base stocks of appropriate compositions, similar/closer, to hydrocracked base oils. The conventionally refined lube base stocks are used as feed in the process to make new generation base oils by this invention. Here base oils of any viscosity grade can be made as the change in their viscosity after processing is very less effected and the end use application will dictate the selection of feed to be processed. The process is based on sort of separation of undesirable components through the use of preferential adsorption of one component over the other. Sulfur content is reduced at its lowest possible level and higher VI is achieved as in the prior art. It therefore represents an advance in the art from view point of economics and manufacturing new generation base oils making use of conventional base stocks which are the only base stocks produced in our refineries todate. The following examples are set forth for purpose of illustration so that those skilled in the art may better understand the invention. It should be understood that these are exemplary only and should not be construed as limiting the invention in any manner. Example 1 New generation base oils were prepared from conventional base oils of light viscosity Ex Indian Refinery. Feed is charged to the column filled with silica / alumina in an 1:11 feed to adsorbent ratio. Percolation was done at a constant elution rate. Properties of the feed stocks processed and the products obtained with material balance are as follows : I. Feedstock Properties (Table Removed) II. Material Balance of Operation, % wt (Table Removed) III. Product Properties (Table Removed) Example 2 Another set of new generation base oil was prepared using a feed stock of interneutral viscosity range. Feed stocks were percolated over a fixed bed of silica / alumina adsorbents using a 1:16 feed to adsorbent ratio and at a constant elution rate. Properties of feed stocks, material balance of operation and product properties are as follows : I. Feedstock Properties (Table Removed) II. Material Balance of Operation, % Weight (Table Removed) III. Product Properties (Table Removed) Example 3 In this example of novel process of making new generation base oils, the same type of feed was taken as in example 1, i.e., light neutral viscosity range. But prior to the percolation of feed, it was subjected to deeper dewaxing to obtain oils of lower pour point. Percolation was done using the same procedure as outlined above. The details of this example are given in table below : I. Feedstock Properties (Table Removed) II. Material Balance of Operation, % Weight (Table Removed) III. Product Properties (Table Removed) Example 4 In this invention of making new generation base oils, type of the feed was the same as taken in example 2 and deeper dewaxing of the feed was done prior to percolation using the same procedure. Other details are as follows : I. Feedstock Properties (Table Removed) II. Material Balance of Operation, % Weight (Table Removed) III. Product Properties (Table Removed) We Claim: 1. An improved process for the preparation of group II / group III lubricant base oils which comprises charging of conventional base oils for adsorption over a organic solvent mediated pre-weted fixed bed of adsorbents column of silica gel / alumina , at an optimal feed to adsorbent ratio ( 1:10 to 1:18), at room temperature (25°C to 35°C) and pressure (atmospheric pressure), diluting the feed using organic solvent such as herein described , eluting by dry compressed air / nitrogen, adding an aliphatic alcohol to the said eluant to desorb the adsorbed material, collecting the resultant to get group ll/group III lubricant base oils. 2. An improved process as claimed in claim 1 wherein the organic solvents used for prewetting, dilution & elution is selected from pentane, hexane cyclohexane. 3. An improved process as claimed in claim 1 and 2 wherein the aliphatic alcohol used for desorption is selected from methanol, ethanol, isopropanol. 4. An improved process for the preparation of group II / group III lubricant base oils substantially described herein described with reference to the examples.

Documents:

205-del-2000-abstract.pdf

205-del-2000-claims.pdf

205-del-2000-correspondence-others.pdf

205-del-2000-correspondence-po.pdf

205-del-2000-description (complete).pdf

205-del-2000-form-1.pdf

205-del-2000-form-19.pdf

205-del-2000-form-2.pdf

205-del-2000-form-3.pdf