Title of Invention	AN IMPROVED PROCESS FOR THE PREPARATION OF AROMATIC RICH HYDROCARBONS USING TITANOSILICATE CATALYST
Abstract	This invention relates to . an improved process for the preparation of aromatic rich hydrocarbons using titanosilicate catalyst. it relates to a reforming process wherein a light naphtha fractions and hydrogen are contacted with a novel catalyst composite material made of a wide pore titanosilicate containing alkali and alkaline earth metals and a transition metal. The process relates to the reforming of hydrocarbons into aromatics over a novel catalyst composite material, the catalyst composite material being a highly basic large pore titanosilicate containing metallic functions capable of dehydrocyclization of alkanes.

Title of Invention

AN IMPROVED PROCESS FOR THE PREPARATION OF AROMATIC RICH HYDROCARBONS USING TITANOSILICATE CATALYST

Abstract

This invention relates to . an improved process for the preparation of aromatic rich hydrocarbons using titanosilicate catalyst. it relates to a reforming process wherein a light naphtha fractions and hydrogen are contacted with a novel catalyst composite material made of a wide pore titanosilicate containing alkali and alkaline earth metals and a transition metal. The process relates to the reforming of hydrocarbons into aromatics over a novel catalyst composite material, the catalyst composite material being a highly basic large pore titanosilicate containing metallic functions capable of dehydrocyclization of alkanes.

Full Text	This invention relates to a process for the preparation of mixture of hydrocrabons rich in aromatics. More specifically, it relates to a reforming process wherein a light naphtha fractions and hydrogen are contacted with a novel catalyst composite material made of a wide pore titanosilicate containing alkali and alkaline earth metals and a transition metal. Reforming processes are used in the industry to obtain high octane gasoline and aromatics from low octane straight run naphtha. The reforming process converts the alkane and cycloalkane components of naphtha into aromatics which have higher octane numbers than the parent hydrocarbons. When aromatics are the required final products, the aromatic rich product of the process called the reformate is extracted with suitable solvent to separate the aromatics from the rest of the material called the raffiate. In the prior-art, most reforming catalysts are of the bifunctional type, being typically platinum supported on an acidic support such as alumina. Additionally, the metal may be promoted with one or more metals such as rhenium, iridium, tin, germanium. Besides, the acidity of the support alumina is usually enhanced with promoters such as chloride and or fluoride ions. Often the catalysts contain platinum and the promoter metals each in the range of 0.2 to 0.8 wt%, besides a chloride (or fluoride) content of 0.5 to 1.5 wt%. The naphtha feed of the desired boiling range is usually contacted in admixture with hydrogen over these catalysts at temperatures in the range of 480 to 540°C and at pressures in the range of 4 to 20 atmospheres. The reactions occurring in catalytic naphtha reforming over the above catalysts are varied and complex and involve both the acidic support and the supported metal function. Usually, the cycloalkane components are readily dehydrogenated over the metallic function into aromatics. On the other hand, the alkane components are more difficult to transform into aromatics. The latter reaction termed dehydrocyclization is believed to proceed by the cooperative action of both the metal and the acidic function. Besides, other reactions such as the isomerization of the linear and less branched alkanes into more branched isomers also occur mostly over the acidic support. The metallic function may also lead to the hydrogenolysis of the hydrocarbons to produce less valuable gaseous products, the object of a good catalyst is to facilitate the dehydrocyclization reaction and to minimize hydrocracking and hydrogenolysis reactions. In general, the transformation of the alkanes into aromatics via dehydrocyclization over prior-art Pt-alumina based catalysts becomes more difficult as the number of carbon atoms present in a chain decreases. For example, the order of reactivity of four typical normal alkanes over platinum-alumina is as follows : n-nonane > n-octane > n-heptane > n-hexane; while more than 90% of the octane may be converted to xylenes, less than 10% of the n - hexane is transformed into benzene. Among the aromatics, the demand for benzene is the most and its production is more than the others. To meet the demand for benzene, expensive processes to convert toluene into benzene via disproportionation or dealkylation have been developed. Hence, the development of catalysts with high selectivity for benzene from C6-alkanes, especially from fractions rich in n-hexane has assumed importance. Zeolites are aluminosilicates containing pores of uniform size of dimensions similar to those of some of organic molecules. These are overly acidic in the protonic form and when used as support for platinum based reforming catalysts lead to excessive cracking and loss of liquid yield. However, the alkali metal exchanged forms of many large pore zeolites have been used successfully as the support for platinum based reforming catalysts. For example, U.S. Pat. No. 3, 755, 486 discloses a process for the aromatization of C6 to C10 hydrocarbons over platinum supported on alkali ion exchanged faujasites. Subsequently, a number of disclosures (U.S. Pat. Nos. 4, 140, 320; 4, 448, 891; 4, 493, 901; 4, 619, 906 etc.) were made that platinum supported on alkali exchanged zeolite L made a good catalyst for the transformation of C6 to Cg alkanes to aromatics (Hughes and others, Proceedings of the 7th International Zeolite Conference, Tokyo, Japan 1986, p. 725). Besides, it has been that the more basic the exchanged ion, the more active is the catalyst for the reaction (Besukhanova and others in J. Chem. Soc. Faraday Trans. I, Vol. 77, p. 1595, year 1981). However, one of the major limitations of the L-zeolite is that it is made up of linear unidirectional noninterconnected channels of about 7A diameter formed from linked cancrinite cages. Such an arrangement restricts the rapid diffusion of molecules through the pore system and hence causes rapid deactivation of the catalyst. Such a deactivation would have been less if the channels were interconnected ( 2 or 3 dimensional) or if they were larger in size. Engelhards Titano Silicate-10 (ETS-10; U.S. Pat. 4, 938, 939) is a wide pore molecular sieve whose framework structure is made up of corner sharing of oxygen atoms of [Ti06] octahedral units with [SiO4] tetrahedral units in such a way that each Ti-ion is linked to four Si-ions and two Ti-ions via O-ions. Details of its structure have been published by Anderson and others in Nature, Vol. 367, p. 347, year 1994. ETS-10 has a 2-dimensional pore system of interconnecting pores with a diameter of > 8A which is larger than that of L zeolite (pore diameter ~ 7A). The Si/Ti ratio of ETS-10 is 5 and with two cations charge balancing each Ti-ion, the overall ion- exchange capacity is similar to that of an aluminosilicate zeolite with a Si/AI ratio of 2.5. The typical Si/A/ ratio of zeolite L is 3, implying a lower ion-exchange capacity than ETS-10 and a consequent lower basicity than ETS-10 on exchange with cations. Besides, as the more basic ions such as rubidium and cesium are larger in size, a considerable amount of pore restriction takes place in zeolite L when exchanged with these ions further aggrevating deactivation. The pore dimensions of ETS-10 being large (>8A) enables it to accommodate the large basic ions without any significant detriment to the movement of the reactants and products. The present invention relates to the reforming of hydrocarbons into aromatics over a novel catalyst composite material, the catalyst composite material being a highly basic large pore titanosilicate containing metallic functions capable of dehydrocyclization of alkanes. Accordingly present invention provides An improved process for the preparation of aromatic rich hydrocarbons using titanosilicate catalyst which comprises: contacting hydrocarbons or mixture of hydrocarbons such as light petroleum fractions having composition such as herein described in admixture with hydrogen characterized in that over a composite titanosilicate material characterized by the XRD data as herein described and having the general composition : (aM-i + bM2 + cM3)Ox : TiO2 : y (SiO2); where a, b and c represent the number of moles of the elements MI, M2 and M3, wherein M-i ions selected from the group hydrogen, lithium, sodium, potassium, rubidium and cesium or their mixture, M2 represents alkaline earth metal from the group magnesium, calcium barium and strontium or their mixture and M3 represents transition metals from the group platinum, palladium, rhenium, ruthenium, iridium and tin or their mixture, at elevated temperatures in the range of 300 to 600°C and pressures in the range of 1 to 20 atmospheres at hydrocarbon feed rate of 0.5 to 5 grams of the feed per hour per gram of the said composite material and hydrogen to hydrocarbon feed molar ratios of 1 to 10, cooling the product at room temperature and separating the liquid fraction from the gaseous fraction by known method. In an embodiment of the present invention the metal MI may be present in the range of 0.008 to 1.2 moles and M2 may be present in the range of 0 to 0.9 moles. In an another embodiment of the present invention the metal M3 may be present in the range of 0 to 0.1 moles. In yet an another embodiment of the present invention the SiO2 / TiO2 molar ratio may be preferably between 4 to 6. In another embodiment of the present invention the molar sum of elements is equivalent to not less than 2 moles of an univalent ion; that is [(a x 1) + (b x 2) + (c x n)] > 2, where n is the valency of the metal M3 and Y is in the range 2 to 10 and x takes a value depending on the moles of Mi, M2 and MS and their valencies According to another feature of the invention, the catalyst composite material is characterized by the x-ray diffraction pattern shown in Table 1 and the framework infrared spectrum shown in Table 2. The synthesis of the titanosilicate molecular sieve in the sodium and potassium forms is carried out as has been described in a copending patent no. 1529 / DEL / 96, ion exchanged with the desired ions selected from Mi or M2 or both and further incorporated with of one or more of the metals from the group, platinum, palladium, rhenium, ruthenium, iridium and tin as described in the copending patent No. 729/del/2000. According to a preferred embodiment, the catalyst composite material is prepared in a mechanically stable form as extrudates, tablets, spheres or spray dried particles using a binder. Examples of materials that can serve as binders include silica, alumina, bentonite, kaolinite and mixtures thereof. The incorporation of the metals from the group platinum, palladium, rhenium, ruthenium, iridium and tin can be carried out either after incorporation of the binder and forming into a mechanically stable form or before such an operation. It is also possible that the above metals are introduced partly before and partly after the binder is incorporated. Table 1 : X-ray diffraction pattern of the titanosilicate (ETS-10) (Table Removed) VS = Very strong; S = Strong; MS = Medium Strong; M = medium; W = weak; VW = Very Weak. Table 2 : Framework infrared vibration frequencies of the titanosilicate (Table Removed) VS = Very strong; S = Strong; MS = Medium strong; W = Weak; VW = Very weak. The present invention is illustrated with the following examples which should not be confirmed to limit the scope of the invention. Example 1 80 g distilled water was added to 52.5 g sodium silicate (28.6% SiO2, 8.82% Na2O, 62.58% H2O) and kept stirring (solution A). Solution (B) was prepared by dissolving 9.3 g NaOH pellets in 50.0 g distilled water and added dropwise to the stirring solution (A). 32.75 g TiCI4 (25.42% TiCI4, 25.92% HCI and 48.66% H2O) was added to the above mixture (A+B). The colourless sticky material formed was kept stirring for one hour (C). 7.8 g potassium fluoride dihydrate dissolved in 36.68 g deionised water was added to (C) and stirred for one hour till free flowing homogeneous gel (pH = 10.8-11.0) at room temperature and then transferred to a stainless steel autoclave (Parr Instruments, USA). Its composition in terms of moles of oxides was as follows: 3.70 Na2O : 0.95 K2O : TiO2: 5.71 SiO2: 171 H2O The crystallization was carried out at 200°C with a stirrer speed of 300 r.p.m. for 14-16 hours. When crystallization was over the autoclave was quenched in water and opened. The solid material was then separated from the mother liquor by suction filtration, washed with deionised water until the pH of the washing was about 10.6-10.9. The powder was then dried in an air oven at 150°C and identified as crystalline titanosilicate having ETS-10 structure by means of X-ray diffraction, the X-ray diffraction pattern being similar to that reported in Ind. Pat. 171483. The chemical composition of the solid material in terms of mole ratio of oxides was found to be : 0.83 Na2O : 0.18 K20 ; TiO2: 5.1 SiO2: 7.28 H2O Example 2 This example illustrates the process for preparing the ion-exchanged forms of the large pore titanosilicate synthesized following example 1. The crystalline material from example 1 was dried at 100°C for 10 hrs and converted into different ion-exchanged forms by exchanging thrice with the required metal substrate solutions (20 ml of 1M solution / g of the catalyst at 90°C for 3 hours). After washing, filtering and drying at 100°C (for 8 hours), the samples were calcined at 480°C for 2 hours. By this method, a number of metals (M) exchanged samples were prepared where M was lithium, sodium, potassium, rubidium, cesium, calcium and barium. Example 3 This example illustrates the procedure for incorporating platinum into the material prepared obtained from example 2. 10 grams of the sample prepared according to example 2 was soaked in 100 ml of a solution of tetraamine platinum (II) nitrate containing 0.1 g of the platinum salt and gently evaporated to dryness over a period of many hours at 60°C with gentle stirring. The material was further dried at 100°C for 8 hrs and calcined at 450°C for 2 hours. The Pt content was 0.4 wt%. Example 4 This example illustrates the preparation of a platinum alumina reforming catalyst of the prior-art. A commercially available alumina monohydrate (water content 30%) solid under the trade name Catapal B was sieved using a 200 mesh (ASTM) screen. 180 g of the 200 mesh material was kneaded with 50 ml of dilute nitric acid containing 3 ml of concentrated HNO3 of Sp. gr. 1.42. The dough was extruded. The extrudates were dried at room temperature (30°C) for 6 hrs., then at 110°C for 10 hrs. and calcined finally at 500°C for 6 hrs. in a flow of dry air. The weight of the extrudates was 123 g. 1000 ml of a solution of hydrochloric acid in distilled water, containing 1.9 g of chloride ions were taken in a 2 liter beaker and the calcined extrudates were added to it. The mixture was agitated occasionally for 2 hrs. At the end of 2 hours, the solution was decanted out and analyzed for chloride ions. The chloride ions picked up by the extrudates was 1.01 wt. %. The extrudates were next dried at 110°C for 6 hrs. 2 liters of a solution containing 1.6 g. of dihydrogen hexachloroplatinate (IV) hexahydrate equivalent to 0.6 g. of platinum metal was taken in a 5 liter beaker and the chlorinated extrudates added to it. The mixture was kept aside for 24 hrs. with occasional agitation. After 24 hrs., the solution was decanted off and the extrudates were dried at 110°C for 10 hrs. followed by calcination at 550°C for 6 hrs. The final composition of the catalyst was 0.6% platinum, 1.0% chlorine, the rest being alumina. Example 5 In this example the activities of platinum containing metal exchanged titanosilicate materials are described. The reforming of n-hexane into benzene was carried out at 450°C and 500°C at a WHSV (weight hourly space velocity = grams of n-hexane passed per gram of catalyst per hour) of 2 hr1 alongwith hydrogen (hydrogen / n-hexane mole ratio of 6) at atmospheric pressure using a tubular fixed bed reactor. The reaction was carried out over the metal exchanged catalysts containing platinum (prepared following examples 1 to 3) and a platinum-alumina catalyst of example 4. The results of the experiments are presented in Table 3. It is obvious from the results of the above experiments that the catalyst composite material of the present invention is more selective in producing benzene from n-hexane. Table 3 : n-Hexane aromatization activity of Pt containing titanosilicate catalyst3 (Table Removed) aReaction Conditions : all titanosilicate catalyst composites contained 0.4 wt.% Pt, Pt-AI2O3 contained 0.6 wt.% Pt; WHSV = 2(h1); Press. = 1 atm.; TOS (Time in Stream) = 2h; H2/n-C6(mole) = 4.5 Example 6 This example reports the results of synthetic mixture of hydrocarbons a typical reforming of a typical synthetic light naphtha cut over a cesium-exchanged catalyst composite material platinum-alumina. The composition of the naphtha feed was : (Table Removed) The experimental conditions were : Temperature : 500°C; Pressure : atmospheric; Weight hourly space velocity = 2 h'1; H2/feed mole ratio = 6; duration of run = 1 hour. The reformate obtained from the cesium exchanged composite material contained 55 wt% benzene and 7 wt% toluene while the reformate from platinum-alumina contained 23 wt% benzene and 8 wt% toluene. We claim: 1. An improved process for the preparation of aromatic rich hydrocarbons using titanosilicate catalyst which comprises: contacting hydrocarbons or mixture of hydrocarbons such as light petroleum fractions having composition such as herein described in admixture with hydrogen characterized in that over a composite titanosilicate material characterized by the XRD data as herein described and having the general composition : (aMi + bM2 + cM3)Ox: TiO2: y (SiO2); where a, b and c represent the number of moles of the elements M1, M2 and M3, wherein M1 ions selected from the group hydrogen, lithium, sodium, potassium, rubidium and cesium or their mixture, M2 represents alkaline earth metal from the group magnesium, calcium barium and strontium or their mixture and M3 represents transition metals from the group platinum, palladium, rhenium, ruthenium, iridium and tin or their mixture, at elevated temperatures in the range of 300 to 600°C and pressures in the range of 1 to 20 atmospheres at hydrocarbon feed rate of 0.5 to 5 grams of the feed per hour per gram of the said composite material and hydrogen to hydrocarbon feed molar ratios of 1 to 10, cooling the product at room temperature and separating the liquid fraction from the gaseous fraction by known method. 2. An improved process according to claim 1 wherein the metal Mi is in the range of 0.008-1.2 moles and M2 is present in the range of 0 to 0.9 moles. 3. An improved process according to claims 1 to 2, wherein the metal M3 is present in the range of 0 to 0.1 moles. 4. An improved process according to claims 1 to 3 wherein the SiO2 / TiO2 molar ratio is preferably between 4 to 6. 5. An improved process for the preparation of aromatic rich hydrocarbons using titanosilicate catalyst substantially as herein described with reference to the examples 5 and 6.

Full Text

This invention relates to a process for the preparation of mixture of hydrocrabons rich in aromatics. More specifically, it relates to a reforming process wherein a light naphtha fractions and hydrogen are contacted with a novel catalyst composite material made of a wide pore titanosilicate containing alkali and alkaline earth metals and a transition metal.
Reforming processes are used in the industry to obtain high octane gasoline and aromatics from low octane straight run naphtha. The reforming process converts the alkane and cycloalkane components of naphtha into aromatics which have higher octane numbers than the parent hydrocarbons. When aromatics are the required final products, the aromatic rich product of the process called the reformate is extracted with suitable solvent to separate the aromatics from the rest of the material called the raffiate. In the prior-art, most reforming catalysts are of the bifunctional type, being typically platinum supported on an acidic support such as alumina. Additionally, the metal may be promoted with one or more metals such as rhenium, iridium, tin, germanium. Besides, the acidity of the support alumina is usually enhanced with promoters such as chloride and or fluoride ions. Often the catalysts contain platinum and the promoter metals each in the range of 0.2 to 0.8 wt%, besides a chloride (or fluoride) content of 0.5 to 1.5 wt%. The naphtha feed of the desired boiling range is usually contacted in admixture with hydrogen over these catalysts at temperatures in the
range of 480 to 540°C and at pressures in the range of 4 to 20 atmospheres.
The reactions occurring in catalytic naphtha reforming over the above catalysts are varied and complex and involve both the acidic support and the supported metal function. Usually, the cycloalkane components are readily dehydrogenated over the metallic function into aromatics. On the other hand, the alkane components are more difficult to transform into aromatics. The latter reaction termed dehydrocyclization is believed to proceed by the cooperative action of both the metal and the acidic function. Besides, other reactions such as the isomerization of the linear and less branched alkanes into more branched isomers also occur mostly over the acidic support. The metallic function may also lead to the hydrogenolysis of the hydrocarbons to produce less valuable gaseous products, the object of a good catalyst is to facilitate the dehydrocyclization reaction and to minimize hydrocracking and hydrogenolysis reactions.
In general, the transformation of the alkanes into aromatics via dehydrocyclization over prior-art Pt-alumina based catalysts becomes more difficult as the number of carbon atoms present in a chain decreases. For example, the order of reactivity of four typical normal alkanes over platinum-alumina is as follows : n-nonane > n-octane > n-heptane > n-hexane; while more than 90% of the octane may be converted to xylenes, less than 10% of the n - hexane is transformed into benzene. Among the aromatics, the demand for benzene is the most and its production is more than the others.
To meet the demand for benzene, expensive processes to convert toluene into benzene via disproportionation or dealkylation have been developed. Hence, the development of catalysts with high selectivity for benzene from C6-alkanes, especially from fractions rich in n-hexane has assumed importance.
Zeolites are aluminosilicates containing pores of uniform size of dimensions similar to those of some of organic molecules. These are overly acidic in the protonic form and when used as support for platinum based reforming catalysts lead to excessive cracking and loss of liquid yield. However, the alkali metal exchanged forms of many large pore zeolites have been used successfully as the support for platinum based reforming catalysts. For example, U.S. Pat. No. 3, 755, 486 discloses a process for the aromatization of C6 to C10 hydrocarbons over platinum supported on alkali ion exchanged faujasites. Subsequently, a number of disclosures (U.S. Pat. Nos. 4, 140, 320; 4, 448, 891; 4, 493, 901; 4, 619, 906 etc.) were made that platinum supported on alkali exchanged zeolite L made a good catalyst for the transformation of C6 to Cg alkanes to aromatics (Hughes and others, Proceedings of the 7th International Zeolite Conference, Tokyo, Japan 1986, p. 725). Besides, it has been that the more basic the exchanged ion, the more active is the catalyst for the reaction (Besukhanova and others in J. Chem. Soc. Faraday Trans. I, Vol. 77, p. 1595, year 1981). However, one of the major limitations of the L-zeolite is that it is made up of linear unidirectional noninterconnected channels of about 7A diameter formed from linked cancrinite cages. Such an arrangement restricts the
rapid diffusion of molecules through the pore system and hence causes rapid deactivation of the catalyst. Such a deactivation would have been less if the channels were interconnected ( 2 or 3 dimensional) or if they were larger in size.
Engelhards Titano Silicate-10 (ETS-10; U.S. Pat. 4, 938, 939) is a wide pore molecular sieve whose framework structure is made up of corner sharing of oxygen atoms of [Ti06] octahedral units with [SiO4] tetrahedral units in such a way that each Ti-ion is linked to four Si-ions and two Ti-ions via O-ions. Details of its structure have been published by Anderson and others in Nature, Vol. 367, p. 347, year 1994. ETS-10 has a 2-dimensional pore system of interconnecting pores with a diameter of > 8A which is larger than that of L zeolite (pore diameter ~ 7A). The Si/Ti ratio of ETS-10 is 5 and with two cations charge balancing each Ti-ion, the overall ion- exchange capacity is similar to that of an aluminosilicate zeolite with a Si/AI ratio of 2.5. The typical Si/A/ ratio of zeolite L is 3, implying a lower ion-exchange capacity than ETS-10 and a consequent lower basicity than ETS-10 on exchange with cations. Besides, as the more basic ions such as rubidium and cesium are larger in size, a considerable amount of pore restriction takes place in zeolite L when exchanged with these ions further aggrevating deactivation. The pore dimensions of ETS-10 being large (>8A) enables it to accommodate the large basic ions without any significant detriment to the movement of the reactants and products.
The present invention relates to the reforming of hydrocarbons into aromatics over a novel catalyst composite material, the catalyst composite material being a highly basic large pore titanosilicate containing metallic functions capable of dehydrocyclization of alkanes.
Accordingly present invention provides An improved process for the preparation of aromatic rich hydrocarbons using titanosilicate catalyst which comprises: contacting hydrocarbons or mixture of hydrocarbons such as light petroleum fractions having composition such as herein described in admixture with hydrogen characterized in that over a composite titanosilicate material characterized by the XRD data as herein described and having the general composition : (aM-i + bM2 + cM3)Ox : TiO2 : y (SiO2); where a, b and c represent the number of moles of the elements MI, M2 and M3, wherein M-i ions selected from the group hydrogen, lithium, sodium, potassium, rubidium and cesium or their mixture, M2 represents alkaline earth metal from the group magnesium, calcium barium and strontium or their mixture and M3 represents transition metals from the group platinum, palladium, rhenium, ruthenium, iridium and tin or their mixture, at elevated temperatures in the range of 300 to 600°C and pressures in the range of 1 to 20 atmospheres at hydrocarbon feed rate of 0.5 to 5 grams of the feed per hour per gram of the said composite material and hydrogen to hydrocarbon feed molar ratios of 1 to 10, cooling the product at room temperature and separating the liquid fraction from the gaseous fraction by known method.
In an embodiment of the present invention the metal MI may be present in the range of 0.008 to 1.2 moles and M2 may be present in the range of 0 to 0.9 moles.
In an another embodiment of the present invention the metal M3 may be present in the range of 0 to 0.1 moles.
In yet an another embodiment of the present invention the SiO2 / TiO2 molar ratio may be preferably between 4 to 6.
In another embodiment of the present invention the molar sum of elements is equivalent to not less than 2 moles of an univalent ion; that is [(a x 1) + (b x 2) + (c x n)] > 2, where n is the valency of the metal M3 and Y is in the range 2 to 10 and x takes a value depending on the moles of Mi, M2 and MS and their valencies
According to another feature of the invention, the catalyst composite material is characterized by the x-ray diffraction pattern shown in Table 1 and the framework infrared spectrum shown in Table 2.
The synthesis of the titanosilicate molecular sieve in the sodium and potassium forms is carried out as has been described in a copending patent no. 1529 / DEL / 96, ion exchanged with the desired ions selected from Mi or M2 or both and further incorporated with of one or more of the metals from the group, platinum, palladium, rhenium, ruthenium, iridium and tin as described in the copending patent No. 729/del/2000. According to a preferred embodiment, the catalyst composite material is prepared in a mechanically stable form as extrudates, tablets, spheres or spray dried particles using a binder. Examples of materials that can serve as binders include silica, alumina, bentonite, kaolinite and mixtures thereof.
The incorporation of the metals from the group platinum, palladium, rhenium, ruthenium, iridium and tin can be carried out either after incorporation of the binder and forming into a mechanically stable form or before such an operation. It is also possible that the above metals are introduced partly before and partly after the binder is incorporated.
Table 1 : X-ray diffraction pattern of the titanosilicate (ETS-10)

(Table Removed)
VS = Very strong; S = Strong; MS = Medium Strong; M = medium; W = weak; VW = Very Weak.
Table 2 : Framework infrared vibration frequencies of the titanosilicate
(Table Removed)
VS = Very strong; S = Strong; MS = Medium strong; W = Weak; VW = Very weak.
The present invention is illustrated with the following examples which should not be confirmed to limit the scope of the invention.
Example 1
80 g distilled water was added to 52.5 g sodium silicate (28.6% SiO2, 8.82% Na2O, 62.58% H2O) and kept stirring (solution A). Solution (B) was prepared by dissolving 9.3 g NaOH pellets in 50.0 g distilled water and added dropwise to the stirring solution (A). 32.75 g TiCI4 (25.42% TiCI4, 25.92% HCI and 48.66% H2O) was added to the above mixture (A+B). The colourless sticky material formed was kept stirring for one hour (C). 7.8 g
potassium fluoride dihydrate dissolved in 36.68 g deionised water was added to (C) and stirred for one hour till free flowing homogeneous gel (pH = 10.8-11.0) at room temperature and then transferred to a stainless steel autoclave (Parr Instruments, USA). Its composition in terms of moles of oxides was as follows:
3.70 Na2O : 0.95 K2O : TiO2: 5.71 SiO2: 171 H2O
The crystallization was carried out at 200°C with a stirrer speed of 300 r.p.m. for 14-16 hours. When crystallization was over the autoclave was quenched in water and opened. The solid material was then separated from the mother liquor by suction filtration, washed with deionised water until the pH of the washing was about 10.6-10.9. The powder was then dried in an air oven at 150°C and identified as crystalline titanosilicate having ETS-10 structure by means of X-ray diffraction, the X-ray diffraction pattern being similar to that reported in Ind. Pat. 171483. The chemical composition of the solid material in terms of mole ratio of oxides was found to be :
0.83 Na2O : 0.18 K20 ; TiO2: 5.1 SiO2: 7.28 H2O
Example 2
This example illustrates the process for preparing the ion-exchanged forms of the large pore titanosilicate synthesized following example 1.
The crystalline material from example 1 was dried at 100°C for 10 hrs and converted into different ion-exchanged forms by exchanging thrice with
the required metal substrate solutions (20 ml of 1M solution / g of the catalyst at 90°C for 3 hours). After washing, filtering and drying at 100°C (for 8 hours), the samples were calcined at 480°C for 2 hours. By this method, a number of metals (M) exchanged samples were prepared where M was lithium, sodium, potassium, rubidium, cesium, calcium and barium.
Example 3
This example illustrates the procedure for incorporating platinum into the material prepared obtained from example 2.
10 grams of the sample prepared according to example 2 was soaked in 100 ml of a solution of tetraamine platinum (II) nitrate containing 0.1 g of the platinum salt and gently evaporated to dryness over a period of many hours at 60°C with gentle stirring. The material was further dried at 100°C for 8 hrs and calcined at 450°C for 2 hours. The Pt content was 0.4 wt%.
Example 4
This example illustrates the preparation of a platinum alumina reforming catalyst of the prior-art. A commercially available alumina monohydrate (water content 30%) solid under the trade name Catapal B was sieved using a 200 mesh (ASTM) screen. 180 g of the 200 mesh material was kneaded with 50 ml of dilute nitric acid containing 3 ml of concentrated HNO3 of Sp. gr. 1.42. The dough was extruded. The extrudates were dried at room temperature (30°C) for 6 hrs., then at 110°C
for 10 hrs. and calcined finally at 500°C for 6 hrs. in a flow of dry air. The weight of the extrudates was 123 g. 1000 ml of a solution of hydrochloric acid in distilled water, containing 1.9 g of chloride ions were taken in a 2 liter beaker and the calcined extrudates were added to it. The mixture was agitated occasionally for 2 hrs. At the end of 2 hours, the solution was decanted out and analyzed for chloride ions. The chloride ions picked up by the extrudates was 1.01 wt. %. The extrudates were next dried at 110°C for 6 hrs.
2 liters of a solution containing 1.6 g. of dihydrogen hexachloroplatinate (IV) hexahydrate equivalent to 0.6 g. of platinum metal was taken in a 5 liter beaker and the chlorinated extrudates added to it. The mixture was kept aside for 24 hrs. with occasional agitation. After 24 hrs., the solution was decanted off and the extrudates were dried at 110°C for 10 hrs. followed by calcination at 550°C for 6 hrs. The final composition of the catalyst was 0.6% platinum, 1.0% chlorine, the rest being alumina.
Example 5
In this example the activities of platinum containing metal exchanged titanosilicate materials are described. The reforming of n-hexane into benzene was carried out at 450°C and 500°C at a WHSV (weight hourly space velocity = grams of n-hexane passed per gram of catalyst per hour) of 2 hr1 alongwith hydrogen (hydrogen / n-hexane mole ratio of 6) at atmospheric pressure using a tubular fixed bed reactor. The reaction was carried out over the metal exchanged catalysts containing platinum
(prepared following examples 1 to 3) and a platinum-alumina catalyst of example 4. The results of the experiments are presented in Table 3.
It is obvious from the results of the above experiments that the catalyst composite material of the present invention is more selective in producing benzene from n-hexane.
Table 3 : n-Hexane aromatization activity of Pt containing titanosilicate catalyst3
(Table Removed)
aReaction Conditions : all titanosilicate catalyst composites contained 0.4 wt.% Pt, Pt-AI2O3 contained 0.6 wt.% Pt; WHSV = 2(h1); Press. = 1 atm.; TOS (Time in Stream) = 2h; H2/n-C6(mole) = 4.5
Example 6
This example reports the results of synthetic mixture of hydrocarbons a typical reforming of a typical synthetic light naphtha cut over a cesium-exchanged catalyst composite material platinum-alumina. The composition of the naphtha feed was :

(Table Removed)
The experimental conditions were : Temperature : 500°C; Pressure : atmospheric; Weight hourly space velocity = 2 h'1; H2/feed mole ratio = 6; duration of run = 1 hour.
The reformate obtained from the cesium exchanged composite material contained 55 wt% benzene and 7 wt% toluene while the reformate from platinum-alumina contained 23 wt% benzene and 8 wt% toluene.

We claim:
1. An improved process for the preparation of aromatic rich
hydrocarbons using titanosilicate catalyst which comprises: contacting
hydrocarbons or mixture of hydrocarbons such as light petroleum
fractions having composition such as herein described in admixture
with hydrogen characterized in that over a composite titanosilicate
material characterized by the XRD data as herein described and
having the general composition : (aMi + bM2 + cM3)Ox: TiO2: y (SiO2);
where a, b and c represent the number of moles of the elements M1,
M2 and M3, wherein M1 ions selected from the group hydrogen,
lithium, sodium, potassium, rubidium and cesium or their mixture, M2
represents alkaline earth metal from the group magnesium, calcium
barium and strontium or their mixture and M3 represents transition
metals from the group platinum, palladium, rhenium, ruthenium,
iridium and tin or their mixture, at elevated temperatures in the range
of 300 to 600°C and pressures in the range of 1 to 20 atmospheres at
hydrocarbon feed rate of 0.5 to 5 grams of the feed per hour per gram
of the said composite material and hydrogen to hydrocarbon feed
molar ratios of 1 to 10, cooling the product at room temperature and
separating the liquid fraction from the gaseous fraction by known
method.
2. An improved process according to claim 1 wherein the metal Mi is in
the range of 0.008-1.2 moles and M2 is present in the range of 0 to
0.9 moles.

3. An improved process according to claims 1 to 2, wherein the metal M3
is present in the range of 0 to 0.1 moles.
4. An improved process according to claims 1 to 3 wherein the SiO2 /
TiO2 molar ratio is preferably between 4 to 6.
5. An improved process for the preparation of aromatic rich
hydrocarbons using titanosilicate catalyst substantially as herein
described with reference to the examples 5 and 6.

Documents:

726-del-2000-abstract.pdf

726-del-2000-claims.pdf

726-del-2000-correspondence-others.pdf

726-del-2000-correspondence-po.pdf

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

726-del-2000-form-1.pdf

726-del-2000-form-19.pdf

726-del-2000-form-2.pdf

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Patent Number

233544

Indian Patent Application Number

726/DEL/2000

PG Journal Number

14/2009

Publication Date

27-Mar-2009

Grant Date

30-Mar-2009

Date of Filing

10-Aug-2000

Name of Patentee

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	TAPAN KUMAR DAS	NATIONAL CHEMICAL LABORATORY, PUNE 411008, MAHARASHTRA, INDIA.
2	SUBRAMANIAN SIVASANKER	NATIONAL CHEMICAL LABORATORY, PUNE 411008, MAHARASHTRA, INDIA.
3	ASHA JEEVAN CHANDWADKAR	NATIONAL CHEMICAL LABORATORY, PUNE 411008, MAHARASHTRA, INDIA.

PCT International Classification Number

C07C 15/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA