Title of Invention

HETEROGENEOUS ACID CATALYST FOR PRODUCING BIODIESEL FROM VEGETABLE OILS AND PROCESS FOR THE PREPARATION THEREOF

Abstract

Heterogeneous acid catalyst for producing biodiesel from vegetable oils and process for the preparation thereof. The catalyst comprises zinc oxide supported on alumino silicate zeolite in the weight ratio 1:2 to 1:5. The process for the preparation of the catalyst comprises coprecipitating zinc and alumino silicate zeolite by reacting an aqueous solution of zinc nitrate with alumino silicate zeolite in the molar ratio 1:2 to 1:5 at 70 to 90 °C with pH adjustment of the reaction at 7 to 7.5 with sodium bicarbonate to precipitate zinc on alumina hydrate, filtering out the precipitate, drying the precipitate at 120 to 130°C and calcining the precipitate at 400 to 500°C. Also a process for producing biodiesel from vegetable oils in a single step transesterification of the vegetable oils. The transesterification of the vegetable oils is carried out with an alcohol in the molar ratio 1:10 to 1:41.1 at 200 to 220°C and 35 to 42 bars pressure in the presence of the above catalyst used in 1 to 5% by weight of the vegetable oils.

Full Text

FORM 2 THE PATENTS ACT, 1970 (39 of 1970) As amended by the Patents (Amendment) Act, 2005 & The Patents Rules, 2003 As amended by the Patents (Amendment) Rules, 2006 COMPLETE SPECIFICATION (See section 10 and rule 13) TITLE OF THE INVENTION Heterogeneous acid catalyst for producing biodiesel from vegetable oils and process for the preparation thereof APPLICANTS Indian Institute of Technology, Bombay, an autonomous research and educational institution established in India by a special Act of the Parliament of the Republic of India under the Institutes of Technology Act 1961, Powai, Mumbai 400076, Maharashtra, India and Tata Consulting Engineers Limited, Matulya Centre-A, 249 Senapati Bapat Marg, Lower Parel (W), Mumbai 400013, Maharashtra, India, an Indian company INVENTORS Mahajani Sanjay, Department of Chemical Engineering, Indian Institute of Technology, Bombay, Powai, Mumbai 400076, Maharashtra, India and Ganesh Anuradda and Singh Dheerendra Kumar, both of Department Energy Science and Engineering, Indian Institute of Technology, Bombay, Powai, Mumbai 400076, Maharashtra, India and Gupta Purshottam Das, Tata Consulting Engineers Limited, Matulya Centre-A, 249 Senapati Bapat Marg, Lower Parel (W), Mumbai 400013, Maharashtra, India, all Indian nationals PREAMBLE TO THE DESCRIPTION The following specification particularly describes the nature of this invention and the manner in which it is to be performed: FIELD OF THE INVENTION This invention relates to a heterogeneous acid catalyst for producing biodiesel from vegetable oils and process for the preparation thereof. This invention also relates to a process for producing biodiesel from vegetable oils using the catalyst. BACKGROUND OF THE INVENTION Biodiesel is a mono-alkyl ester of long chain fatty acids produced from renewable feed stocks like vegetable oils and animal fats. It is gaining worldwide attention as an alternative fuel for diesel due to the depleting fossil fuel resources. Inedible vegetable oils mostly produced from tree borne seeds are an attractive low cost feed stock for bio diesel production. Biodiesel is produced from triglycerides in vegetable oils by transesterification with alcohol, which is the most common method for biodiesel production. Transesterification is the displacement of alcohol from an ester. Transesterification is a reversible reaction and proceeds essentially by mixing the reactants. The presence of catalyst in the transesterification reaction accelerates the conversion rate and thus results in higher conversion efficiency i.e higher yield of biodiesel. The transesterification of oil (triglycerides) with alcohol in the presence of a catalyst gives biodiesel (fatty acid methyl esters) and glycerol as a byproduct. It is a stoichiometric reaction requiring 1 mole of triglycerides (oil) and 3 moles of alcohol but excess alcohol is used to drive the reversible reaction forward to increase the yield of alkyl ester and to achieve phase separation of glycerol. Presently, most of the commercial processes for producing esters by transesterification reaction employ alkali based homogeneous catalysts. Alkaline catalysts such as NaOH/KOH are being preferred over acid catalysts to achieve higher conversion rate. However, the FFA (free fatty acids) reacts with alkali catalyst to form soap which reduces the biodiesel yield and makes separation of glycerol difficult. Therefore, use of alkali catalyst gets restricted to the feed stocks with low FFA content, generally less than 1%. Alternatively, two steps esterification are carried out to mitigate FFA presence wherein FFA to fatty acid methyl ester (FAME) is converted by acid catalyst like sulphuric acid or hydrochloric acid followed by alkali catalyst to complete the reaction. The two steps conversion process becomes cost prohibitive due to the low overall conversion efficiency and its complexity. Also, homogeneous catalyst based biodiesel production is slow and complex. Steps like oil pre-treatment, product purification and phase separation are long. Further the process requires large quantity of water for product washing. Edible oils such as soybean, canola, sunflower, rapeseed or palm are mostly generally used in developed countries for conversion to biodiesel. Because of the low percentage of FFA in such oils, transesterification of such oils by the conventional alkali catalyst route is possible on a commercial scale. However, replacement of homogeneous catalyst by heterogeneous catalysts for transesterification is advantageous in many ways. For instance, the process is simplified as there is no need to replace and wash the catalyst and environmental pollutants are reduced. • Further, biodiesel production can be made cheaper using heterogeneous catalysts. Many heterogeneous catalysts have been reported to catalyze the transesterification of vegetable oils. Aluminium oxide and/or iron oxide catalyst is reported to be used in EP0198243 for the preparation of alkyl esters of carboxylic acids, in particular alkyl esters of fatty acids. Zinc or nickel silicate catalyst and copper and zinc chromite catalyst are reported to be used in British Patent No 795573 to tranesterify triglycerides with alcoholes. Zinc aluminate catalyst is described in US 6878837 to produce alkyl esters of fatty acids. US 5908946 describes a process for the production of esters from vegetable oils or animal oils with alcohols in the presence of a catalyst comprising a mixture of zinc oxide, aluminum oxide and zinc aluminates that corresponds to the formula: ZnAl2O4, x ZnO, y A12O3, where x and y are each between 0 and 2, and wherein at least 10% of total ZnO is in the form of ZnAl2O4 The catalyst may comprise a zinc spinel or zinc aluminate or zinc oxide in the form of powder, extrudates or balls. The catalyst has a surface area of 10 to 200 m2/g, a pore volume of 0.2 to 1.2 cm3/g and a pore distribution between 0.01 and 0.1 micron. Preferably the catalyst has a surface area of 50 to 200 m2/g and a pore volume that is greater than 0.3 cm3/g. Preferably at least 30% of total ZnO is in the form of ZnAl204. The above patents in general use for transesterification edible varieties of vegetable oils which contain low FFA, for conversion into FAME. Heterogeneous catalysts described in the above patents are not known to be used for conversion of non-edible vegetable oils into biodiesel on a commercial scale due to the high FFA content therein, generally in the range of 8 - 15%. Edible oils such as soybean, canola, sunflower, rapeseed or palm are generally used for conversion to biodiesel, mostly in developed countries. These edible oils contain low free fatty acid say within 1% and thus the process of transesterification by the conventional alkali catalyst route has been possible on commercial basis. In tropical and subtropical climatic countries like India, cultivation of trees bearing oil seeds is being promoted, especially in large areas of degraded waste land which is unfit for agricultural production. Many varieties of such trees have been planted in these countries to promote biodiesel production. Among these trees Jatropha curcas and Pongomia Pinnata (Karanja) are prominent. The oils extracted from these tree borne oil seeds have similar characteristics as edible oils but possess certain degree of toxicity and thus termed as inedible. The inedible oils contain high FFA contents, varying from 8 - 15%. These FFA levels are far beyond the 1% FFA limit generally prescribed for the transesterification of vegetable oils using an alkaline catalyst. Chemically the oils/fats consist of triglycerides molecules of long chain fatty acids that are ester bonded to a single glycerol molecule. The high FFA content oil is problematic for conventional homogeneous alkali catalyzed route for bio diesel conversion as this leads to soap formation that interferes in the reaction as well as with separation of glycerol. OBJECTS OF THE INVENTION An object of the invention is to provide a heterogeneous acid catalyst for producing biodiesel from vegetable oils, which catalyst is very stable and environmental friendly. Another object of the invention is to provide a heterogeneous acid catalyst for producing biodiesel from vegetable oils, which catalyst enables the transesterification to be carried out in a single step and improves the reaction rate within reduced time to increase the conversion efficiency and productivity. Another object of the invention is to provide a process for the preparation of a heterogeneous acid catalyst for producing biodiesel from vegetable oils, which catalyst is very stable and environmental friendly. Another object of the invention is to provide a process for the preparation of a heterogeneous acid catalyst for producing biodiesel from vegetable oils, which catalyst enables the transesterification to be carried out in a single step and improves the reaction rate within reduced time to increase the conversion efficiency and productivity. Another object of the invention is to provide a process for producing biodiesel from vegetable oils, which process gives high reaction rate within reduced time to increase conversion rate and productivity. Another object of the invention is to provide a process for producing biodiesel from vegetable oil, which process is simple and easy to carry out. DETAILED DESCRIPTION OF THE INVENTION According to the invention there is provided a heterogeneous acid catalyst for producing biodiesel from vegetable oils by transesterification of the vegetable oils with alcohol, the , catalyst comprising zinc oxide supported on alumino silicate zeolite in the weight ratio 1:2 to 1:5. According to the invention there is also provided a process for the preparation of a heterogeneous catalyst for producing biodiesel from vegetable oils by transesterification of vegetable oils with alcohol, the process comprising coprecipitating zinc and alumino silicate zeolite by reacting an aqueous solution of zinc nitrate with alumino silicate zeolite in the molar ratio 1:2 to 1:5 at 70 to 90 °C with pH adjustment of the reaction at 7 to 7.5 with sodium bicarbonate to precipitate zinc on alumina hydrate, filtering out the precipitate, drying the precipitate at 120 to 130°C and calcining the precipitate at 400 to 500°C. According to the invention there is also provided a process for producing biodiesel from vegetable oils in a single step transesterification, wherein the transesterification of the vegetable oils is carried out with an alcohol in the molar ratio 1:10 to 1:41,1 at 200 to 220°C and 35 to 42 bars pressure in the presence of a catalyst comprising zinc oxide supported on alumino silicate zeolite in the weight ratio 1:2 to 1:5 and wherein the catalyst is used in 1 to 5% by weight of the oils. Preferably the zinc nitrate and alumino silicate zeolite are in the weight ratio 1:3. Preferably the alumino silicate zeolite is ZSM - 5 (Zeolyst, USA), The catalyst may comprise a bentonite binder in 8 to 30% by weight of the zinc oxide and alumino silicate zeolite. Preferably the bentonite binder is in 8 to 20% by weight of the zinc oxide and alumino silicate zeolite. Preferably the binder is selected from sodium or potassium bentonite or calcium bentonite or a combination thereof. Preferably the catalyst with the binder is in the form of pellets. Preferably the catalyst has surface area of 100 to 1000m2/gm, pore volume 0.5 to 2.5 cm /gm and pore size distribution in the range of 17 A to 3000 A. Preferably the catalyst is used for transesterification in 4 to 5% by weight of the vegetable oils. Preferably the reaction of zinc nitrate with alumino silicate zeolite is carried out at 70°C. Preferably the precipitate is calcined at 420 to 500°C. Preferably, the catalyst is used for transesterification in 4 to 5% by weight of the vegetable oils. Preferably the transesterification of the vegetable oils is carried out at 200°C. Preferably the vegetable oil is inedible oil. Preferably the inedible vegetable oil contains 8 to 15% free fatty acids. Preferably the inedible oil is Jatropha oil or Karanja oil. Preferably the vegetable oil and alcohol are in the molar ratio 1:30 1:41.1, preferably 1:41.1. Preferably the alcohol is methanol. Preferably the transesterification is carried out for 20 to 40 minutes. The alumino silicate zeolite support or carrier used in the catalyst of the invention is preferably ZSM - 5 which is a highly porous material through out its structure and has an intersecting two dimensional pore structure. Therefore, the ZnO gets deposited on the ZSM -5 uniformly. The interior of the support structure with its atomic-scale dimensions, is the catalytically active surface and plays an active role as a catalyst as well. High thermal stability of ZSM-5 enables calcinations at higher temperatures. During calcination controlled incorporation of acid centres in the intra-crystalline surface of the support takes place to obtain increased reaction rate. The catalyst of the invention is of the chemical formula ZnO, NanAlnSig6.nO192,16H2O (0 The following examples are illustrative of the invention but not limitative of the scope thereof: Example 1 Both edible and non-edible oils were analyzed for FFA (free fatty acids) content and the analytical data were as listed in the following Tablel: Table 1 Oil FFA (wt %) Edible oil 0.66 0.42 Sunflower oil Palmolein oil Inedible oil 10.6 8.3 Jatropha oil Karanja oil Compositions of FFA present in the inedible oils were further analyzed in gas chromatography mass spectrometer and the results were as listed in the following Table 2 : Table 2 Inedible oil Fatty acids compositions (wt %) Palmitolei acid (16:1) Palmitic acid (16:0) Stearic acid (18:0) Oleic acid (18:1) Linoleic acid (18:2) Jatropha oil 1.21 17.57 7.49 32.46 41.27 Karanja oil — 22.42 7.44 48.02 22.12 Example 2 Transesterification of Karanja oil and Jatropha oils was carried out with methanol and with and without known heterogeneous catalysts in batch mode in an autoclave in the generally reported molar ratio of methanol and oil (41.1:1). Catalyst (3% by wt) was added to the mixture of oil and methanol. After the transesterification, the reaction mixture was cooled and catalyst particles were separated by centrifuge. The mixture of methyl esters, methanol and glycerol was subjected to simple distillation for removal of the methanol from the mixture. After the distillation, two layers or phases (oil phase and aqueous phase) were observed. The oil phase (upper layer) consisted of methyl esters and un-reacted triglycerides, while the aqueous phase (lower layer) mainly contained methanol and glycerol. The oil phase (upper layer) was separated from the mixture and subjected to vacuum distillation to obtain biodiesel. Catalysts used in the transesterification and transesterification procedure and experimental results were as under: a) Calcium oxide calcined at 575°C for 4 hours was used for transesterification of Jatropha oil at 214°C. Presence of significant amount of FFA in the oil caused soap formation as CaO being the base catalyst. No conversion was observed for CaO catalyst. b) Transesterification of Jatropha oil was carried out for 15 minutes at 200oC and 35 bars pressure with and without sulphated zirconia calcinated at 620°C for 4 hours and the results were as given in the following Table 3: Table 3 Experiment No Transesterification % Conversion 1 without catalyst 29.8 2 with catalyst 65.58 3 reused from Experiment 2 directly without washing, drying and recalcining 22.81 4 reused from Experiment 2 after washing with acetone, drying and recalcining at 620°C 53.93 It was observed that the sulphated zirconia catalyst was deactivated when reused for transesterification. c) Transesterification of Jatropha oil was carried out with and without zinc oxide for 15 minutes at 200°C and 35 bars pressure. Zinc oxide used was without calcination and with calcination at 400°C and 800°C for 4 hours. The results were as given in the following Table 4: Table 4 Experiment No Transesterification % Conversion 1 without catalyst 20.80 2 ZnO without calcination 37.16 3 ZnO calcined at 400°C 44.56 4 ZnO recovered from Experiment 2 after washing with acetone, drying and calcining 47.10 5 ZnO calcined at 800°C 52.53 6 ZnO recovered from from Experiment 5 after washing with acetone, drying and calcining 55.79 7 ZnO from Experiment 5 reused directly without washing, drying and calcining 63.65 8 ZnO from Experiment 5 reused directly without washing, drying and calcining 64.36 It was observed that ZnO catalyst gave moderate conversion of 45 to 65 % at different calcined temperatures. The catalyst was found stable and reusable without getting deactivated. It was also observed that triglycerides get converted to diglyceride, diglyceride get converted to mono glycerides and monoglycerides get converted to alkyl ester in a single step. Example 3 A solution of zinc nitrate (1M) was dissolved in distilled water and was heated to 70°C. Alumino silicate zeolite was added to the solution of zinc nitrate and agitated at 75°C so as to form slurry. ZSM-5 (Zeolyst, USA) having silica to alumina ratio of 30 was used. The weight ratio of ZnO to ZSM-5 was maintained at 1:3. Sodium bicarbonate was slowly added to the slurry till the pH became 7.2. The slurry was agitated for another 30 minutes; the precipitate was filtered out and washed with cold water to remove any traces of sodium nitrate. The precipitate was dried at 120 °C and calcined at various temperatures as stated in the following Example 4. The catalyst (zinc oxide deposited or supported on alumina-silicate zeolite) had very high surface area in the range of 100-1000 m2/gm, pore volume in the range of 0.5 to 2.5 cm3/gm and pore size distribution in the range of 17 A to 3000 A. The catalyst had the structure of the formula ZnO, NanAlnSi96-nOi92*16H2O (0 Example 4 Catalysts of Example 3 after drying were calcined and pelletised with sodium bentonite (10 % by weight). The catalysts were used to transesterify Karanja oil with methanol in the molar ratio 1:41 in an autoclave. Transesterification time was 15 minutes at 200°C and 35 bars pressure. The catalyst loading was 3% (2.25 gm). The results were as shown in the following Table 5: Table 5 Experiment No Catalyst calcination time (hrs) Catalyst calcination temperature (°C) Conversion (%) 1 1 350 67.7 2 2 400 75.15 3 3 420 83.2 4 4 500 80.9 It is seen from Table 5 that high conversion rates were obtained with calcination temperatures of 400 to 500°C and calcination temperature of 420°C gave the highest conversion rate. Example 5 Catalyst pellets were prepared as described in Example 4. Calcination of the catalyst was carried out at 420°C for 4 hours. The catalyst was used to transesterify Karanja oil with methanol (molar ratio 1:41.1) in an autoclave. Catalyst loading was 3% (2.25 gm) and the reaction was carried out at 200°C and 42 bars pressure. The results were as shown in the following Table 6: Table 6 Experiment No Transesterification time (Minutes) Conversion (%) 1 10 53.99 2 20 81.80 3 30 96.32 4 40 96.71 It is seen from Table 6 that the conversion rate was slow for the first 10 minutes and increased with increase in reaction time. The conversion efficiency increased with the time from 20 minutes to 30 minutes and remained almost constant thereafter. The catalyst gave more than 96% conversion rate within 30 minutes. Example 6 Catalyst pellets were made as described in Example 4. Calcination was carried out at 420°C for 4 hours. The catalyst was used to transesterify Karanja oil with methanol (molar ratio 1:41.1) in an autoclave. Catalyst loading was 3% (2.25 gm) and reaction pressure was 42 bars and reaction time was 45 minutes. The results were as shown in the following Table 7: Table 7 Experiment No Reaction Temp (°C) Conversion (%) 1 190 66.39 2 200 96.32 3 210 93.15 4 220 93.06 It is seen from Table 7 that the conversion rate increased with increase in reaction temperature from 190 to 200 °C and then there was a downward trend with subsequent increase in the reaction temperature. The reaction temperatures of 200 - 220°C resulted in the maximum conversion rate with reaction temperature 200°C giving the highest yield. Example 8 Catalyst pellets made as described in Example 4 and calcined at 420°C. for 4 hours was used to transesterify Karanja oil with methanol in an autoclave. Catalyst loading was 3% (2.25 gm) and reaction pressure was 42 bars and reaction was carried out for 45 minutes at 220°C and 42 bars pressure. The results were as shown in the following Table 8: Table 8 Experiment N o Molar Ratio Conversion (%) 1 1:10 83.9 2 1:20 85.71 3 1:30 92.98 4 1:41.1 93.06 It is seen from Table 8 that molar ratios of 1:30 and 1:41.1 gave high conversion rates. Example 9 Catalyst pellets prepared as described in Example 4 and calcined at 450°C for 4 hours was used to transesterify Karanja oil with methanol (molar ratio 1:41.1) in an autoclave with and without the catalyst. The reaction was carried out for 30 minutes at 200°C and pressure of 42 bars. The results were as shown in the following Table 9: Table 9 Experiment No Catalyst loading (%) Conversion (%) 1 0 20.06 2 0.25 61.32 3 0.60 76.60 4 1.0 92.57 5 2.0 94.86 6 3.0 95.5 7 4.0 96.2 8 5.0 96.6 It is seen from the Table 9 that the conversion rate was low without the catalyst and that the conversion rate increased with catalyst loading and was high at catalyst loading in the range of 1% to 5%. However, the conversion rate did not increase further when the catalyst loading was 4-5%. Example 10 Catalyst pellets prepared as described in Example 4 and calcined at 420°C for 4 hours was used to transesterify Karanja oil with methanol (molar ratio 1:41.1) in an autoclave. Catalyst loading was 3% (2.5gm) and reaction was carried out for 30 minutes at 220oC and 42 bars pressure. The results were as shown in the following Table 10. Table 10 Experiment No Bentonite loading (%) Conversion (%) 1 8 95.07 2 20 95.90 3 25 91.34 4 30 76.10 5 50 59.00 It is seen from the Table 10 that the conversion rate was almost constant with bentonite loading from 8-20%. Increase in the bentonite loading beyond 20% resulted in sharp reduction in the conversion rate. Example 11 Catalyst of Example 4 was used to transesterify Karanja oil with methanol (molar ratio 1:41.1) in an autoclave 5 times consecutively. Catalyst loading was 3% (2.5gm) and reaction was carried out for 30 minutes at 210°C and 42 bars pressure. The results were as shown in the following Table 11. Table 11 Experiment No Conversion (%) 1 96.55 2 97.05 3 97.48 4 97.50 5 98.59 It is seen from the Table 11 that the conversion rate remained almost the same for continuous use of the catalyst 5 times. It establishes the reusability of the catalyst in continuous mode of transesterification of triglycerides. We claim: 1. A heterogeneous acid catalyst for producing biodiesel from vegetable oils by transesterification of the vegetable oils with alcohol, the catalyst comprising zinc oxide supported on alumino silicate zeolite in the weight ratio 1:2 to 1:5. 2. The heterogeneous catalyst as claimed in claim 1, wherein the weight ratio of zinc oxide to alumino silicate zeolite is 1:3. 3. The heterogeneous catalyst as claimed in claim 1 of 2, wherein the alumino silicate zeolite is ZSM-5. 4. The heterogeneous catalyst as claimed in any one of claims 1 to 3, which comprises a bentonite binder in 8 to 30% by weight of the zinc oxide and alumino silicate zeolite. 5. The heterogeneous catalyst as claimed in any one of claims 1 to 3, which comprises a bentonite binder in 8 to 20% by weight of the zinc oxide and alumino silicate zeolite. 6. The heterogeneous catalyst as claimed in claim 4 or 5, wherein the bentonite is selected from sodium or potassium bentonite or calcium bentonite or a combination thereof. 7. The heterogeneous catalyst as claimed in anyone of claims 4 to 6, wherein the catalyst is in the form of pellets. 8. The heterogeneous catalyst as claimed in any one of claims 1 to 7, wherein the catalyst has surface area of 100 to 1000 m2/gm, pore volume 0.5 to 2.5 cm3/gm and pore size distribution in the range of 17 A to 3000 A. 9. A process for the preparation of a heterogeneous catalyst for producing biodiesel from vegetable oils by transesterification of vegetable oils with alcohol, the process comprising coprecipitating zinc and alumino silicate zeolite by reacting an aqueous solution of zinc nitrate with alumino silicate zeolite in the molar ratio 1:2 to 1:5 at 70 to 90 °C with pH adjustment of the reaction at 7 to 7,5 with sodium bicarbonate to precipitate zinc on alumina hydrate, filtering out the precipitate, drying the precipitate at 120 to 130°C and calcining the precipitate'at 400 to 500°C. 10. The process as claimed in claim 9, wherein the zinc nitrate and alumino silicate zeolite are in the weight ratio 1:3. 11. The process as claimed in claim 9 or 10, wherein the alumino silicate zeolite is ZSM -5. 12. The process as claimed in any one of claims 9 to 11, wherein the calcined precipitate is mixed with a bentonite binder in 8 to 30% by weight of the zinc oxide and alumino silicate zeolite. 13. The process as claimed in any one of claims 9 to 11, wherein the calcined precipitate is mixed with a bentonite binder in 8 to 20% by weight of the zinc oxide and alumino silicate zeolite. 14. The process as claimed in claim 12 or 13, wherein the binder is selected from sodium or potassium bentonite or calcium bentonite or a combination thereof. 15. The process as claimed in any one of claims 12 to 14, wherein the calcined precipitate is formed into pellets. 16. The process as claimed in any one of claims 9 to 15, wherein the catalyst has surface area of 100 to 1000 m2/gm, pore volume 0.5 to 2.5 cm3/gm and pore size distribution in the range of 17 A to 3000 A. 17. The process as claimed in any one of claims 9 to 16, wherein the reaction of zinc nitrate with alumino silicate zeolite is carried out at 70°C. 18. The process as claimed in any one of claims 9 to 17, wherein the precipitate is calcined at 420 to 500°C. 19. A process for producing biodiesel from vegetable oils in a single step transesterification of the vegetable oils, wherein the transesterification of the vegetable oils is carried out with an alcohol in the molar ratio 1:10 to 1:41.1 at 200 to 220°C and 35 to 42 bars pressure in the presence of a catalyst comprising zinc oxide supported on alumino silicate zeolite in the weight ratio 1:2 to 1:5 and wherein the catalyst is used in 1 to 5% by weight of the vegetable oils. 20. The process as claimed in claim 19, wherein the catalyst is used in 4 to 5% by weight of the vegetable oils. 21. The process as claimed in claim 19 or 20, which is carried out for 20 to 40 minutes. 22. The process as claimed in any one of claims 19 to 21, wherein the weight ratio of zinc oxide to alumino silicate zeolite is 1:3. 23. The process as claimed in any one of claims 19 to 22, wherein the alumino silicate zeolite is ZSM-5. 24. The process as claimed in any one of claims 19 to 23, wherein the catalyst comprises a bentonite binder in 8 to 30% by weight of the zinc oxide and alumino silicate zeolite. 25. The process as claimed in any one of claims 19 to 23, wherein the catalyst comprises a bentonite binder in 8 to 20% by weight of zinc oxide and alumino silicate zeolite. 26. The process as claimed in claim 24 or 25, wherein the bentonite is selected from sodium or potassium bentonite or calcium bentonite or a combination thereof. 27. The process as claimed in any one of claims 24 to 26, wherein the catalyst is in the form of pellets. 28. The process as claimed in anyone of claims 19 to 27, wherein the catalyst has a surface area of 100 to 1000 m2/gm, pore volume of 0.5 to 2.5 cm3/gm and pore size distribution in the range of 17 A to 3000 A. 29. The process as claimed in any one of claims 19 to 28, wherein the transesterification of the vegetable oils is carried out at 200°C. 30. The process as claimed in any one of claims 19 to 29, wherein the vegetable oil is inedible vegetable oil. 31. The process as claimed in claim 30, wherein the inedible vegetable oil contains 8 to 15% free fatty acids. 32. The process as claimed in claim 30 or 31, wherein the inedible vegetable oil is Jatropha oil or Karanja oil. 33. The process as claimed in any one of claims 19 to 32, wherein the vegetable oil and alcohol are in the molar ratio 1:30 : 1:41 A, preferably 1:41.1, 34. The process as claimed in any one of claims 19 to 33, wherein the alcohol is methanol.

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2134-MUM-2010-ABSTRACT(18-7-2014).pdf

2134-mum-2010-abstract.pdf

2134-MUM-2010-CLAIMS(AMENDED)-(18-7-2014).pdf

2134-MUM-2010-CLAIMS(AMENDED)-(22-11-2013).pdf

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2134-MUM-2010-FORM 2(TITLE PAGE)-(22-11-2013).pdf

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2134-MUM-2010-SPECIFICATION(AMENDED)-(18-7-2014).pdf

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