MX2008004696A - A process for the preparation of hydrocarbon fuel - Google Patents

Abstract

The present invention provides a process for the preparation of hydrocarbon fuels, which comprises contacting fatty acid glycerides with alcohols in the presence of a solid, double metal cyanide catalyst at a temperature in the range of 150°to 200°C for a period of 2 - 6 hrs. and separating the catalyst from the above said reaction mixture to obtain the desired hydrocarbon fuel.

Description

PROCESS FOR THE PREPARATION OF HYDROCARBON FUEL FIELD OF THE INVENTION The present invention relates to a process for the preparation of hydrocarbon fuels. More particularly, it relates to an efficient process for the production of hydrocarbon fuel which comprises contacting fatty acid glycerides with alcohols in the presence of a solid metallic double cyanide catalyst. The solid metallic double cyanide catalyst used in the present invention is described and disclosed in co-pending Hindu patent application No. 2723 / DEL / 2005.

BACKGROUND OF THE INVENTION In recent years there has been renewed interest in alternatives for petroleum-based fuels. Alternative fuels must be technically acceptable, economically competitive, environmentally acceptable and readily available. The need for these fuels arises mainly from the point of view of preserving the global environment and that related to the long-term supplies of fuels based on conventional hydrocarbons. Among the different possible sources, diesel fuels derived from triglycerides (vegetable oil / animal fat) present a promising alternative. Although triglycerides can supply diesel engines, their viscosities and poor cold flow properties have led to the investigation of various derivatives. Fatty acid methyl esters derived from triglycerides and methanol known as bio-diesel have received the most attention. Vegetable oils are widely available from a variety of sources. Unlike hydrocarbon-based fuels, the sulfur content of vegetable oils is close to zero and therefore the environmental damage caused by sulfuric acid is reduced. The main advantages of using bio-diesel are its renewability, emission of better quality gas, its biodegradability and since all the organic carbon present is photosynthetic of origin, it does not contribute to increase the level of C02 in the atmosphere and therefore to the greenhouse effect. Various processes have been developed for the transesterification of triglycerides: (1) transesterification of glycerides catalyzed by alcohol base (catalysts - alkoxides and alkali metal hydroxides, as well as sodium and potassium carbonates), (2) esterification catalyzed by direct acid with alcohols (catalysts - Brónsted acids, preferably sulfonic acid and sulfuric acid), and (3) conversion of oil to fatty acids and then to alkyl esters with acid catalysis. However, the old route (ie, the base-catalyzed reaction) is the most economical and in fact, is in practice in various countries for the production of bio-diesel (J. Braz. Chem. Soc. Vol. 9, No. 1, Year 1998, pages 199-210, J. Am. Oil, Chem. Soc. Vol. 77, No. 12, Year 2000, pages 1263-1266, Fuel Vol. 77, No. 12, Year 1998, pages 1389-1391, Bioresource Tech. Vol. 92, Year 2004, pages 55-64, Bioresource Tech. Vol. 92, Year 2004, pages 297-305, Renewable Sustainable Energy Rev. Vol. 9, Year 2005, pages 363- 378). Alkali metal alkoxides (such as CH30Na for methanolysis) are the most active catalysts, since they provide very high yields (> 98%) of fatty acid alkyl esters at short reaction times (30 minutes) even if applied at low Molar concentrations (0.5 mole%) (J. Food Composition and Analysis Year 2000, Vol. 13, pages 337-343). However, they require high quality oils and the absence of water, which makes them unsuitable for typical industrial processes (J. Braz. Chem. Soc. Vol. 9, No. 1, Year 1998, pages 199-210). The alkali metal hydroxides (NaOH and KOH) are cheaper than the metal alkoxides, although they require increasing the concentration of the catalyst (1-2 mole%). NaOH is more superior to KOH since the latter and other alkali hydroxides provide more soponified products than the bio-fuel. Recently, enzymatic transesterification using lipase, has become more attractive for the production of bio-fuel, because the glycerol produced as a by-product can be easily recovered and the purification of fatty acid esters is relatively simple to carry out . However, the main obstacle to commercializing this system is the cost of the production of lipase (J. Mol.Cata.B: Enzymatic Vol. 17, Year 2002, pages 133-142). The use of immobilized lipases in the synthesis of fatty acid methyl esters from sunflower and soybean oils was reported by Soumanou and Bornscheuer and Watanabe. et al. (Enzy Microbiol Tech. Vol. 33, Year 2003, page 97; J. Mol. Catal. B: Enzymatic Vol. 17, Year 2002, pages 151-155). They found that the immobilized enzyme is active for at least 120 hours during five batch cycles without significant loss of activity. Among the various lipases investigated, the enzyme from Pseudomonas fluorescens (Amano AK) exhibited the highest oil conversion. Khare and Nakajima (Food Chem. Vol. 68, Year 2000, pages 153-157) also reported the use of the immobilized lipase enzyme.

The cost is the main factor that decreases the commercialization of bio-fuel. The replacement of the homogeneous catalyst with a solid catalyst eliminates the processing costs associated with homogeneous catalysts. Leclercq et al. (J. Am. Oil, Chem. Soc. Vol. 78, Year 2001, page 1161) studied the transesterification of rape seed oil in the presence of NaX exchanged with Cs and commercial hydrotalcite catalysts (K 2200). At a high methanol to oil ratio of the reaction time of 275 and 22 hours at reflux in methanol, the NaX exchanged with Cs gave a conversion of 70% while a 34% conversion was obtained with respect to hydrotalcite. The catalysts of ETS-4 and ETS-10 provide conversions of 85.7% and 52.7%, respectively at 220 ° C and a reaction time of 1.5 hours (U.S. Patent No. 5,508,457). Suppes et al. (J. Am. Oil, Chem. Soc. Vol. 78, Year 2001, page 139) reached a conversion of 78% at 240 ° C and > 95% at 160 ° C, using calcium carbonate rock as a catalyst. Not long ago, Suppes et al. reported the use of zeolite X exchanged for Na, K and Cs, ETS-10, NaX occluded with NaOx and sodium azide in the transesterification of soybean oil with methanol (Appl. Catal. A: Gen. Vol, 257, Year 2004 , page 213). Furuta et al. (Catal. Commun. Vol. 5, Year 2004, pages 721-723) describe the production of bio-diesel from soybean oil and methanol at 200-300 ° C, using solid super-acid catalysts of tin sulphate and zirconium oxides with oil conversions greater than 90%. The use of tin complexes immobilized in ionic liquids for vegetable oil alcoholysis was reported by Abreu et al. (J. Mol. Catal. A: Chem. Vol. 227, Year 2005, pages 263-267, J. Mol. Catal. A: Chem. Vol. 209, Year 2004, pages 29-33). Kim et al. reported the use of heterogeneous basic catalysts (Na / NaOH / Al2C > 3) for the methanolysis of vegetable oils. U.S. Patent No. 5,713,965 describes the production of bio-diesel, lubricants and fuel and lubricant additives by transesterification of triglycerides with short-chain alcohols in the presence of an organic solvent such as alkane, arene, chlorinated solvent, or Petroleum ether using a lipase catalyst derived from Mucor miehei or Candida Antarctica. Patents Nos. WO 00/05327 Al, WO 02/28811 Al, WO 2004/048311 Al, WO 2005/021697 Al and WO 2005/016560 Al and U.S. Patent Nos. 5,578,090; 6,855,838; 6,822,105; 6,768,015; 6,712,867; 6,642,399; 6,399,800; 6,398,707; 6,015,440, also show the production of fatty acid alkyl esters using either lipase catalysts or catalysts of metal ions. U.S. Patent No. WO 2004/085583 A1, describes the transesterification of fats with methanol and ethanol in the presence of a solid acid catalyst having ultra-strong acidic properties in a short time at approximately ordinary pressure. The production of diesel from pure soybean oil or coconut oil is not economical, so it is convenient to use cheaper alternative feedstocks such as animal fat or used cooking oil or oil from seeds of wild plants. similar to jojoba and jatropha. The animal fat and oil used contain high amounts of free fatty acid (FFA) contents. The FFA is saponified with the alkaline-based transesterification catalyst that leads to low yield, makes it difficult to separate the products and increases the cost of production. In those cases, a two-step process where in the first step an acid catalyst esterifies the free fatty acids to methyl esters and in the second step a basic catalyst transesterifies the triglycerides, generally used in the preparation of diesel. An efficient solid catalyst, which can perform this in a single step is quite convenient. The present invention relates to a process, which eliminates most of the above disadvantages. It is related to the production of hydrocarbon fuels (diesel oil) which comprises the reaction of vegetable oils or fats with C1-C5 alcohols at moderate conditions using a novel, solid, reusable, metallic double cyanide catalyst. The oil in the raw material is a triglyceride or a mixture of fatty acids and glycerides. One of the metals of the double metal cyanide catalyst is Zn2 + while the other is a transition metal ion, preferably Fe. The coexistence of Zn and Fe in the active site binding through cyano bridges makes it efficient to transform Feeding raw materials containing fatty acids in a single step to alkyl esters of fatty acid. The catalyst could be easily separated by centrifugation or by simple filtration and could be reused. More importantly, the catalyst is quite efficient and only a small amount (~ 1% by weight of oil) is needed to carry out the reaction. The process is atomically efficient and the reaction conditions similar to temperature and pressure are only moderate. Unlike conventional basic catalysts, the catalyst of the present invention is more efficient even in the presence of water-in-oil impurities. By therefore, there are no limitations on the quality of the oil to be used with the catalysts of the present invention.

OBJECTIVES OF THE INVENTION The main objective of the present invention is to provide a reusable, efficient heterogeneous catalyst and a process for the preparation of hydrocarbon fuels with high yields. Another objective is to provide a one-step process for the production of hydrocarbon fuels from used oils or oils or fats that contain a significant amount of fatty acids. Still another objective of the present invention is to produce fuels by transesterification of vegetable oils or fats with a C1-C5 alcohol at moderate conditions and shorter reaction times.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method for the preparation of hydrocarbon fuel, which comprises contacting fatty acid glycerides with an alcohol in the presence of a solid metal, double cyanide catalyst, at a temperature in the variation of 150-200 ° C, for a period of 2-6 hours, cool the above reaction mixture to a temperature in the variation of 20-35 ° C, filter the above reaction mixture to separate the catalyst, followed by removal of the untreated alcohol from the resulting filtrate by vacuum distillation to obtain the desired hydrocarbon fuel. In one embodiment of the present invention, the molar ratio of fatty acid glyceride to alcohol used is in the range of 1: 6 to 1:12. In yet another embodiment, the concentration of the solid metal double cyanide catalyst is 1-2% by weight of fatty acid glyceride. In yet another embodiment, the solid metal double cyanide catalyst used has the molecular formula: Zn3M2 (CN) n (ROH) .xZnCl2.yH20 wherein, R is a tertiary butyl, is a transition metal ion, x varies from 0 to 0.5, and varies from 3-5 and n is 10 or 12. Still in another embodiment, the transition metal ion used is Fe or Co. Still in another mode, the fuel hydrocarbon obtained is methyl esters of fatty acid. Still in another embodiment, the hydrocarbon fuel obtained is diesel oil. In yet another embodiment the source of fatty acid glyceride used is vegetable oil or animal fat. In yet another embodiment, the vegetable oil used is selected from the group consisting of coconut oil, sunflower oil, soybean oil, mustard oil, olive oil, cottonseed oil., rapeseed oil, margarine oil, jojoba oil, jatropha oil and mixtures thereof. In yet another embodiment, the alcohol used is selected from the group consisting of methanol, ethanol, propanol, butanol, pentanol and mixtures thereof. In yet another embodiment the solid metal double cyanide complex catalyst used can be easily separated from the reaction mixture and can be reused in various recycling experiments without significant loss of activity. In yet another embodiment, the% molar conversion of oil or fat to hydrocarbon fuel obtained is in the range of 90-95 mol% based on the yield of isolated glycerol and the selectivity of the fuel is greater than 95%.

DETAILED DESCRIPTION OF THE INVENTION In the investigations leading to the present invention, it was found that the double metal cyanide catalysts are quite efficient and could easily be separated from the products for further reuse. The catalysts, mineral acid, alkaline bases and lipases of the prior art need additional expense for catalyst separation. A catalyst system that can be easily separated, for example, the catalyst of the present invention is beneficial and leads to an economical process and without ecological damage. Therefore, the solid catalysts of the present invention are not only efficient but also avoid the tedious process of the catalyst recovery characteristic of the prior art processes. The catalyst system of the present is efficient without using any additional solvent. The solid metallic double cyanide catalyst has the molecular formula: Zn3M2 (CN) n (ROH) .XZnCl2.yH20 wherein, R is tertiary butyl, x varies from 0 to 0.5, and varies from 3-5 and n is 10 or 12. The catalyst has the physicochemical characteristics listed in Table 1.

TABLE 1: Physico-chemical characteristics of the double metal cyanide catalyst (Fe-Zn) Texture characteristics: Total surface area (SBET) 38.4 m2 / g External surface area (SExt. 24.1 m2 / g Micropore area 14.3 m2 / g Average pore diameter 3.9 nm Total pore volume 0.037 cc / g Elementary analysis: Content% of C 23.3 Content% of H 2.24 Content% of N 17.3 Morphology (SEM): particles with spherical shape Spectral characteristics: Band positions FT-IR / (in cirf1) 2096 (v (C = N)), 1230 (v (C-O)), 500 (v (Fe-C)) Visible bands with ÜV diffuse reflectance light (in nm) 405, 330, 278, 236 and 208 The catalyst of the present invention is prepare as described in EXAMPLE 1, by making react an aqueous solution of ZnCl2, a solution aqueous K4Fe (CN) 6 and a poly (ethylene glycol) block poly (propylene glycol) in poly (ethylene glycol) block of a tri-block copolymer (E02o-P07o-E02o; molecular weight of approximately 5800) dissolved in tert-butanol at ambient conditions (25-40 ° C) and activation at 170-200 ° C. In still another embodiment, the concentration of the catalyst in the reaction mixture is 1-2% by weight of oil. A feature of the process of the present invention is that it eliminates soponification. Another characteristic of the process of the present invention is that the catalyst is a solid and the reaction is carried out in a heterogeneous condition, the fuel product is a liquid and the solid catalyst can be easily separated from the products by centrifugation / filtration. for additional reuse. Still in another feature, the reaction is conducted without using any solvent. The present invention is illustrated hereinafter with the examples, which are illustrative only and are not to be construed as limiting the scope of the present invention in any way.

EXAMPLE 1 This example illustrates the preparation of the Fe-Zn double metal cyanide catalyst of the present invention. In a typical catalyst preparation, K4 [Fe (CN) 6] (0.01 mol) was dissolved in double distilled water (40 mi) (Solution 1). ZnCl 2 (0.1 mol) was dissolved in a mixture of distilled water (100 ml) and tertiary butanol (20 ml) (Solution 2). Poly (ethylene glycol) block of poly (propylene glycol) block of poly (ethylene glycol) (??? 20-PO70-EO20; molecular weight of about 5800) (15 g) was dissolved in a mixture of 2 ml of distilled water and 4 ml. ? my tertiary butanol (Solution 3). Solution 2 was added to solution 1 for 60 minutes at 50 ° C with vigorous stirring. During the addition, white precipitation occurred. Then, solution 3 was added to the above reaction mixture over a period of 5 minutes and stirring was continued for an additional 1 hour. The solid cake formed was filtered, washed with distilled water (500 ml) and dried at 25 ° C for 2-3 days. This material was activated at 180-200 ° C for 4 hours before using it in the reactions.

EXAMPLE 2 This example describes the preparation of fatty acid methyl esters (diesel oil) from coconut oil and methanol. In a typical reaction, coconut oil (5 g), methanol (molar ratio of oil: methanol = 1: 6) and Fe-Zn catalyst of double metal cyanide (50 mg, 1% by weight oil) were charged. in a 100-ml stainless steel autoclave that had a Teflon coating. The autoclave was closed and placed in a rotary synthesis reactor (Hiro Co., Japan, Mode-KH 02; rotational speed = 30 rpm) and the reaction was conducted under heterogeneous pressure at 170 ° C for 4 hours. Then it was allowed to cool to 25 ° C. First, the catalyst was separated by centrifugation / filtration of the reaction mixture. Then, by distillation under vacuum, the unreacted alcohol was removed in the reaction mixture. Petroleum ether (60 ml) and methanol (20 ml) were added to separate the glycerol by-product from the reaction mixture. The methanol layer that contained the glycerol by-product was separated. This glycerol separation process was repeated 2-3 times. The glycerol was isolated by distillation of methanol under vacuum. Later, the ether portion was distilled to obtain the esterified products. A portion of the esterified products (100 mg) was diluted with dichloromethane (1 g) for analysis by gas chromatography. The products were identified by GC-MS.

EXAMPLE 3 This example illustrates the preparation of fatty acid methyl esters (diesel oil) from sunflower oil and methanol. In a typical reaction, the Sunflower oil (5 g), methanol (molar ratio of oil: methanol = 1: 6) and double-cyanide Fe-Zn catalyst (50 mg, 1% by weight oil) were charged in a stainless steel autoclave of 100 mi that had a Teflon coating. The autoclave was closed and placed in a rotary synthesis reactor (Hiro Co., Japan, Mode-KH 02; rotational speed = 30 rpm) and the reaction was conducted under heterogeneous pressure at 170 ° C for 4 hours. Then it was allowed to cool to 25 ° C. The products were isolated by vacuum distillation.

EXAMPLE 4 This example describes the preparation of fatty acid methyl esters (diesel oil) from soybean oil and methanol. In a typical reaction, soybean oil (5 g), methanol (molar ratio of rmetanol oil = 1: 6) and Fe-Zn catalyst of double metal cyanide (50 mg, 1% by weight of oil) were charged to a 100 ml stainless steel autoclave that had a Teflon coating. The autoclave was then placed in a reactor for rotary synthesis (Hiro Co., Japan, Mode-KH 02; rotational speed = 30 rpm) and the reaction was conducted under heterogeneous pressure at 170 ° C for 4 hours. Then it was allowed to cool to 25 ° C. The products were isolated by vacuum distillation.

EXAMPLE 5 This example describes the preparation of fatty acid methyl esters (diesel oil) from margarine oil and methanol. In a typical reaction, margarine oil (5 g), methanol (molar ratio of oil: methanol = 1: 6) and Fe-Zn catalyst of double metal cyanide (50 mg, 1% by weight oil) were charged. in a 100 ml stainless steel autoclave that had a Teflon coating. The autoclave was then placed in a reactor for rotary synthesis (Hiro Co., Japan, Mode-KH 02; rotational speed = 30 rpm) and the reaction was conducted under heterogeneous pressure at 170 ° C for 4 hours. Then it was allowed to cool to 25 ° C. The products were isolated by vacuum distillation.

EXAMPLE 6 This example describes the preparation of fatty acid methyl esters (diesel oil) from margarine oil used / cooked and methanol. In a typical reaction, the margarine oil used / cooked (5 g), methanol (molar ratio of oil: methanol = 1: 6) and Fe-Zn catalyst of double metal cyanide (50 mg, 1% by weight of oil ) were loaded into a 100 ml stainless steel autoclave that had a Teflon coating. The autoclave was then placed in a reactor for synthesis rotary (Hiro Co., Japan, Mode-KH 02; rotational speed = 30 rpm) and the reaction was conducted under heterogeneous pressure at 170 ° C for 4 hours. Then it was allowed to cool to 25 ° C. The products were isolated by vacuum distillation.

EXAMPLE 7 This example describes the preparation of fatty acid alkyl esters (hydrocarbon fuel) from coconut oil and butanol. In a typical reaction, margarine oil (5 g), butanol (molar ratio of oil: methanol = 1: 6) and Fe-Zn catalyst of double metal cyanide (50 mg, 1% by weight oil) were charged in a 100 ml stainless steel autoclave that had a Teflon coating. The autoclave was then placed in a rotary synthesis reactor (Hiro Co., Japan, Mode-KH 02; rotational speed = 30 rpm) and the reaction was conducted under heterogeneous pressure at 170 ° C for 4 hours. Then it was allowed to cool to 25 ° C. The products were isolated by vacuum distillation.

EXAMPLE 8 This example describes the preparation of hydrocarbon fuel from sunflower oil and butanol. In a typical reaction, sunflower oil (5 g), butanol (molar ratio of oil: methanol = 1: 6) and catalyst Fe-Zn of double metallic cyanide (50 mg, 1% by weight oil) were loaded in a 100 ml stainless steel autoclave that had a Teflon coating. The autoclave was then closed and placed in a rotary synthesis reactor (Hiro Co., Japan, Mode-KH 02; rotational speed = 30 rpm) and the reaction was conducted under heterogeneous pressure at 170 ° C for 4 hours. Then it was allowed to cool to 25 ° C. The products were isolated by vacuum distillation.

EXAMPLE 9 This example describes the preparation of hydrocarbon fuel from margarine oil and propanol or butanol. In a typical reaction, margarine oil (5 g), propanol or butanol (molar ratio of imethanol oil = 1: 6) and Fe-Zn catalyst of double metal cyanide (50 mg, 1% by weight of oil) loaded in a 100 ml stainless steel autoclave that had a Teflon coating. The autoclave was then closed and placed in a rotary synthesis reactor (Hiro Co., Japan, Mode-KH 02; rotational speed = 30 rpm) and the reaction was conducted under heterogeneous pressure at 170 ° C for 4 hours. Then it was allowed to cool to 25 ° C. The products were isolated by vacuum distillation. TABLE 2 lists the results of the catalytic activity studies illustrated in Examples 2-9.

T7ABLA-2: Preparation of hydrocarbon fuel: catalytic activity of double metal cyanides 15 ADVANTAGES 1. The process has the unique combined advantages of high conversion accompanied with high selectivity for hydrocarbon fuels. 2. The catalyst can be easily separated from the product mixture and no problems related to soponification were found. 3. The catalyst of the present invention is quite efficient for the preparation of hydrocarbon fuel from vegetable oil or fat and C1-C5 alcohols.

Claims (12)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. A process for the preparation of hydrocarbon fuel, characterized in that it comprises contacting glycerides of fatty acid with an alcohol in the presence of a solid metal double cyanide catalyst, at a temperature in the range of 150-200 ° C, for a period of 2-6 hours, cooling the above reaction mixture to a temperature in the variation of 20-35 ° C, filter the above reaction mixture to remove the catalyst, followed by removal of the unreacted alcohol from the resulting filtrate by vacuum distillation to obtain the desired hydrocarbon fuel.
2. 2. The process according to claim 1, characterized in that the molar ratio of fatty acid glyceride to alcohol used is in the range from 1: 6 to 1:12.
3. 3. The process according to claim 1, characterized in that the concentration of solid metal double cyanide catalyst used is 1-2% by weight of fatty acid glyceride.
4. 4. The process in accordance with the claim 1, characterized in that the solid metal double cyanide catalyst used has a molecular formula: Zn3M2 (CN) n (ROH). xZnCl2. and H20 wherein, R is tertiary butyl, M is a transition metal ion, x ranges from 0 to 0.5, and varies from 3-5 and n is 10 or 12.
5. 5. The process according to claim 4, characterized in that the transition metal ion used is selected from Fe, Co and Cr.
6. 6. The process according to claim 1, characterized in that the hydrocarbon fuel obtained is alkyl esters of Cg-C23 · 7 fatty acid.
7. The process according to claim 1, characterized in that the hydrocarbon fuel obtained is diesel oil.
8. 8. The process according to claim 1, characterized in that the source of fatty acid glyceride used is vegetable oil or animal fat.
9. The process according to claim 8, characterized in that the vegetable oil used is selected from the group consisting of coconut oil, sunflower oil, soybean oil, mustard oil, olive oil, cottonseed oil, rape seed oil, margarine oil, jojoba oil, jatropha oil and mixtures thereof.
10. The process according to claim 1, characterized in that the alcohol used is selected from the group consisting of methanol, ethanol, propanol, butanol, pentanol and mixtures thereof.
11. 11. The process according to claim 1, characterized in that the solid metal double cyanide complex catalyst used can be easily separated from the reaction mixture and used again in various recycling experiments without significant loss of activity. .
12. 12. The process according to claim 1, characterized in that the% molar conversion of oil or fat to hydrocarbon fuel obtained is in the range of 90-95 mol% based on the yield of glycerol isolated and the fuel selectivity is higher to 95%.