PL206797B1 - Biofuel production method for self-ignition engines - Google Patents

Description

C10L 1/10 (2006.01) (22) Date of notification: 10.05.2006

Patent Office of the Republic of Poland (54) Method of producing biofuel for compression ignition engines (73) The right holder of the patent:

INSTITUTE OF INDUSTRIAL CHEMISTRY PROF. IGNACEGO MOŚCICKIEGO, Warszawa, PL (43) Application was announced:

12.11.2007 BUP 23/07 (45) The following was announced about the grant of the patent:

30.09.2010 WUP 09/10 (72) Inventor (s):

JACEK KIJEŃSKI, Warsaw, PL MAŁGORZATA JAMRÓZ, Warsaw, PL WITOLD TĘCZA, Raszyn, PL

MAŁGORZATA JAROSZ, Warsaw, PL WIESŁAWA WALISIEWICZ-NIEDBALSKA, Warsaw, PL

ANTONI MIGDAŁ, Radom, PL (74) Representative:

item. stalemate. Królikowska Anna Industrial Chemistry Research Institute prof. Ignacy Mościcki

PL 206 797 B1

Description of the invention

The subject of the invention is a method of producing a biofuel for compression ignition engines, containing as main components C1-C2 alkyl esters of fatty acids and tert-butyl or tert-amyl glycerol ethers.

Fatty acid methyl or ethyl esters are used directly or in mixture with hydrocarbon fractions of petrochemical origin as biofuel for diesel vehicles. In industrial processes, these esters are obtained mainly from triglycerides of fatty acids, including those contained in vegetable oils, in the reaction of their transesterification with aliphatic alcohols. Typical catalysts for triglyceride transesterification reactions are strong bases, e.g., anhydrous sodium or potassium hydroxides dissolved in the corresponding alcohols.

As a result of the transesterification reaction of fatty acid triglycerides with alcohols, apart from the main product being fatty acid alkyl esters, a by-product - glycerin is obtained. Glycerin from the reaction mixture is separated in the form of a watered glycerin fraction, contaminated with inorganic salts and salts of free fatty acids (soaps). The glycerin content in these fractions varies widely between 40-80%. Economically justified secondary processing and management of the glycerin fraction is the main problem to be solved related to the efficiency of industrial production of biofuel for diesel engines.

An example of technological solutions for the transesterification of fatty acid triglycerides contained in vegetable oils in the presence of liquid (homogeneous) alkaline catalysts is the method of producing a mixture of C1-C4 alkyl fatty acid esters, presented in Polish patent specification 163 379. The above-mentioned method of transesterification of fatty acid triglycerides it is multi-stage and requires the use of various technological procedures necessary to obtain diesel fuel of a quality corresponding to the market requirements. The technological operations necessary to effectively carry out the triglyceride transesterification process according to the discussed method include pre-treatment of the starting triglycerides with C1-C4 alcohols in the presence of acid catalysts, neutralization and dehydration of the reaction mixture, and then transesterification of pre-purified triglycerides with C1-C4 alcohols in the presence of homogeneous catalysts alkaline.

In recent years, a process has been developed for the catalytic transesterification of fatty acid triglycerides with aliphatic alcohols using heterogeneous alkaline catalysts such as potassium carbonate, potassium fluoride and lithium nitrate (Chemical Engineering vol. 111, No. 1, p. 15, 2004). This process ensures a high conversion of triglycerides (92-94%) and enables the separation of pure glycerin from the reaction mixture without energy-consuming purification processes.

One of the known methods of glycerin management is the process of its etherification with the use of olefinic hydrocarbons, presented in the German patent application DE 4222183. The process of glycerin etherification with C3-C14 olefinic hydrocarbons according to this method is carried out at a temperature of 50-120 ° C and a pressure of 0.5 -2.5 MPa, in the presence of acid catalysts such as cation exchanger, p-toluenesulfonic acid, sulfonosuccinic acid and dodecylbenzene sulfonic acid. The glycerin etherification process with C3-C10 olefinic hydrocarbons presented in the Polish patent application P-371 959 takes place at a temperature of 55-120 ° C in the presence of known acid catalysts (Amberlyst 35 cation exchanger) in a two-stage manner, with the first stage of etherification being carried out at a temperature of higher than the second degree. This method of carrying out the etherification reaction provides a higher conversion of glycerin compared to other known methods.

The products of the glycerin etherification reaction with olefinic hydrocarbons are glycerol tri-, di- and monoethers, which are used, inter alia, as high-quality components improving the performance properties of diesel oils used in diesel engines.

US Patent 6,015,440 describes a new method of producing biofuel for diesel powered vehicles. The process is based on the transesterification of fatty acid triglycerides with methyl alcohol in the presence of homogeneous alkaline KOH or NaOH catalysts, and then the separation of pure glycerin from the reaction mixture by means of special energy-consuming technological procedures and its etherification with isobutene in the presence of acidic catalysts such as sulfation exchangers.

The biofuel obtained in this process consists of fatty acid methyl esters (approx. 88%) and glycerol tri and tert-butyl diethers (approx. 12%). This fuel is compared to typical oil

The diesel fuel produced from crude oil is characterized by very good operational properties, including a suitably low crystallization temperature, reduced viscosity and reduced emission to the atmosphere of such harmful products of fuel combustion, such as carbon monoxide and aldehydes.

Despite the high quality of the biofuel produced by the method described in the US patent, it should be stated that the technological process of its production is multi-stage and complicated. It is characterized, inter alia, by the initial separation of the reaction mixture obtained in the process of transesterification of fatty acid triglycerides into a fraction of fatty acid methyl esters and a glycerin fraction containing, in addition to glycerin, unreacted alcohol and spent catalyst. In order to obtain pure glycerol and fatty acid methyl esters devoid of traces of alkaline catalyst, both technological streams are separately subjected to a purification process, which includes, among others, a unit for washing with water and neutralization of the alkaline catalyst.

Another disadvantage of the above-mentioned method of biofuel production is also the fact that the product obtained in the process of glycerol etherification contains, apart from glycerol tert-butyl di- and triethers, unreacted glycerin and a large amount of the unfavorable component - glycerol tert-butyl monoether (21%), which is needed for remove the mixture. Both glycerin and glycerol tert-butyl monoether must be removed from it by extraction with water and distillation, and then returned to the glycerin etherification node.

It was found that biofuel for self-ignition engines containing mixtures of fatty acid methyl or ethyl esters and glycerol tert-butyl or tert-amyl ethers can be obtained, with a method devoid of the above-mentioned disadvantages, if the technological process of its production is carried out according to the method being the subject of the present invention. .

The essence of the process according to the invention consists in the fact that, in the first stage, the transesterification of fatty acid triglycerides contained in vegetable oils or fats of vegetable and animal origin with methyl or ethyl alcohol is carried out in the presence of liquid alkaline KOH or NaOH catalysts or in the presence of solid alkaline catalysts such as, for example, potassium fluoride. The reaction mixture obtained in the process of transesterification of triglycerides, after distilling the unreacted alcohol and neutralizing the alkaline catalyst with an inorganic or organic acid, containing methyl or ethyl esters of fatty acids, glycerin and a small amount of free fatty acids, is directly reacted in the second stage with isobutene or isoamylenes (2 - methylobutene-1 and 2-methylbutene-2) in the presence of known acidic catalysts (cation exchangers, p-toluenesulfonic acid, high-silicon zeolites and others).

When the above-mentioned reaction mixture is contacted with isobutene or isoamylenes, a glycerol etherification reaction takes place to form glycerol tert-butyl or tert-amyl ethers. The reaction products obtained in the second stage after the distillation of unreacted isobutene (or isoamylenes) contain practically no glycerin and, after isolating isobutene dimers, they are a ready-made high-quality biofuel for diesel engines, consisting of fatty acid methyl or ethyl esters and a mixture of tert-butyl di- and triethers ( or tertamyl) glycerin.

The method of producing biofuel for compression ignition engines, containing as main components methyl or ethyl esters of fatty acids and tert-butyl or tert-amyl ethers of glycerol, by transesterification of triglycerides of fatty acids with methyl or ethyl alcohol in the presence of liquid or solid alkaline catalysts, is characterized by is that the reaction mixture obtained after transesterification, containing fatty acid methyl or ethyl esters, glycerin, unreacted alcohol and alkaline catalyst, is neutralized or the solid catalyst is removed and then the alcohol is separated from it, or the alcohol is first separated and then subjected to neutralization or removal of the solid catalyst, and the mixture is reacted with isobutene or isoamylenes in the presence of an acid catalyst.

Preferably, the reaction mixture obtained after transesterification, after separating off the unreacted alcohol and neutralizing or removing the alkaline catalyst, is reacted with isobutene or isoamylenes at a temperature of 50-110 ° C, for 1-10 hours, with the molar ratio of isobutene or isoamylenes to that contained in the mixture. glycerin 2-6: 1.

PL 206 797 B1

Thanks to this method of biofuel production, the technological scheme of the process is significantly simplified, a high degree of glycerol conversion is obtained, and the resulting mixture of glycerol tert-butyl or tert-amyl ethers is characterized by a very low content of unfavorable monoether, compared to the mixture of ethers obtained in the process of etherification alone. glycerin. Another advantage of the biofuel production method according to the invention is that free fatty acids, possibly present in triglyceride transesterification products, are esterified in reaction with isobutene to form tert-butyl esters, which are a valuable component of the biofuel obtained in this way.

The method of obtaining biofuel for compression ignition engines according to the invention, presented in a simplified manner in Fig. 1, consists in the fact that in the first stage a mixture of methyl or ethyl alcohol (A) and triglycerides of fatty acids (B) contained in vegetable oils or fats of vegetable origin or animal, is subjected to the transesterification process in the reactor (1) in the presence of liquid or solid alkaline catalysts. The transesterification process is carried out at a temperature of 30-90 ° C with a molar ratio of alcohol to triglycerides of 3-10: 1 and for 1-3 hours. From the obtained reaction mixture (C), first the unreacted alcohol is separated in the distillation apparatus (2) and returned to the transesterification reactor (1), and then the entire reaction mixture, free of alcohol (D), is subjected in a known manner to the process of neutralizing the alkaline catalyst in the apparatus ( 3).

An alternative solution for the processing of the reaction mixture obtained in the reactor (1) in the process of transesterification of triglycerides is that this mixture is first subjected to the alkaline catalyst neutralization process in the apparatus (3 ') and then the unreacted alcohol is distilled off therefrom.

The products of the transesterification reaction (E) obtained after neutralization of the alkaline catalyst, containing fatty acid methyl or ethyl esters and glycerin, are subjected to the second stage of glycerin etherification with isobutene or isoamylenes (F) in the reactor (4). The glycerin etherification process is carried out in the presence of acidic catalysts such as sulfocationites, p-toluenesulfonic acid, zeolites and others at a temperature of 50-110 ° C, with a molar ratio of isobutene or amylenes to glycerin 1-6: 1 and time 1-6. 10 hours.

From the reaction mixture (G) obtained in the reactor (1), unreacted olefinic hydrocarbon (F) (isobutene or isoamylenes) is distilled off in the apparatus (5), which is returned to the glycerol etherification reactor (4). Then, from the obtained mixture (H) in the device (6), the by-products of isobutene or isoamylenes by-products (I) are separated by distillation, thus obtaining high-quality biofuel for diesel engines (J). This fuel consists of fatty acid methyl or ethyl esters, a mixture of glycerol tert-butyl or tert-amyl di- and triethers, and a small amount of monoether.

The isobutene oligomers (2.4,4-trimethylpentene-1 and 2,4,4, -trimethylpentene-2) obtained by bypassing in the glycerol etherification process can be used directly or after hydrogenation to isooctane as high-quality motor gasoline components.

The method of producing a biofuel for compression ignition engines according to the invention is shown in the following examples.

P r z x l a d I.

To a glass reactor of 500 ml capacity equipped with a reflux condenser and a stirrer were added 100 g of methyl alcohol and 5 g of a catalyst containing 18.9% potassium fluoride supported on alumina, and characterized by a surface area of 74.7 m ² / g. After switching on the stirrer and heating the contents of the reactor to the temperature of 40 ° C, 150 g of rapeseed oil with a specific weight of 0.911 g / cm ² and a free fatty acid content of 0.1% were added dropwise to the reactor, and then the whole mixture was stirred at a temperature of 40-45 ° C for 1 hour. After completion of the reaction and cooling the contents of the reactor to room temperature, the entire reaction mixture was allowed to stand for 1 hour and then separated therefrom by decanting 0.2 g of solid catalyst. From the reaction mixture obtained, 84 g of unreacted methyl alcohol were isolated by distillation to give 164 g of a product containing 90.2 wt.% As a distillation residue. % fatty acid methyl esters and 9.8 wt. glycerin. The reaction mixture obtained above in the transesterification process in the amount of 164 g was introduced into a 1000 ml autoclave, to which also 82 g of the isobutene fraction containing 60 wt.% Were introduced. % of isobutene, 28.4 wt. -butene-1 and 11.6% by weight of isobutane, and 4 g of Amberlyst 35 catalyst. The mixture was heated at 90 ° C for 6 hours while stirring vigorously. After cooling the contents of the reactor to room temperature, the excess of unreacted isobutene fraction was removed, and then the liquid, one-phase reaction product in the amount of 182.4 g was subjected to chromatographic analysis. The obtained product contained 83.2% by weight of fatty acid methyl esters, 12.1% by weight of glycerol tert-butyl trieter, 0.7% by weight of glycerol tert-butyl ether, 0.1% by weight of glycerin and 3.9% by weight of isobutene dimers. (2,4,4-trimethylpentene-1 and 2,4,4-trimethylpentene-2). After distilling the by-products of isobutene dimers, a biofuel containing 86.6 wt.% Was obtained. fatty acid methyl esters, 12.6 wt.% of glycerol tert-butyl di- and triethers, 0.7 wt. % of glycerol tert-butyl monoether and 0.1 wt. glycerin. The obtained biofuel was characterized by a kinematic viscosity at 20 ° C - 5.86 mm ² / s and a cetane number of -54.

P r z x l a d II.

To the glass reactor described in Example 1, 150 g of ethyl alcohol and 8 g of the catalyst described in Example 1 were introduced. After the stirrer was turned on and the contents of the reactor heated to 60 ° C, 150 g of rapeseed oil with the properties as in Example 1 were added dropwise to the reactor, then it was intensively stirred at the temperature of 75-80 ° C for 2 hours. After completion of the reaction and cooling the contents of the reactor to room temperature, the entire reaction mixture was subjected to a centrifugation process to separate small amounts of 0.15 g of solid catalyst. From the reaction mixture obtained, 128 g of unreacted ethyl alcohol were isolated by distillation to obtain 169 g of a product containing 90.8% by mass as a distillation residue. % fatty acid ethyl esters and 9.2 wt. glycerin. Then 169 g of the product from the transesterification process, 85 g of the isobutene fraction with the composition presented in Example 1 and 4 g of Amberlyst 35 catalyst were introduced into the autoclave with a capacity of 1000 ml. The whole was heated at 90 ° C for 6 hours while stirring intensively. After cooling the contents of the reactor to room temperature, the excess of unreacted isobutene fraction was removed, and then the liquid, single-phase reaction product in the amount of 187.6 g was subjected to chromatographic analysis. The obtained product contained 84.0% by weight of fatty acid ethyl esters, 11.3% by weight of glycerol tert-butyl di- and triethers, 0.3% by weight of glycerine tert-butyl monoether, 0.1% by weight of glycerol and 4.3% by weight of isobutene dimers. . After distilling the isobutene diners, a biofuel with the following composition was obtained: 87.8 wt.%. fatty acid ethyl esters, 11.8 wt.% of glycerol tert-butyl di- and triethers, 0.3 wt.% % of glycerol tert-butyl monoether and 0.1 wt. glycerin. The biofuel was characterized by a kinematic viscosity at 20 ° C - 5.92 mm ² / s and a cetane number of -55.

P r x l a d III.

100 g of rapeseed oil with the properties as in Example 1 was introduced into a glass reactor with a capacity of 500 ml, equipped with a reflux condenser and a stirrer, and the contents of the reactor were heated to a temperature of about 30 ° C, and then a mixture of 30 g of methyl alcohol and 5 g of hydroxide was added dropwise to the reactor. of sodium, and the mixture was vigorously stirred at 30 ° C for 1 hour. After completion of the reaction and cooling the contents of the reactor to room temperature, the reaction mixture was neutralized with a methanolic solution of concentrated sulfuric acid, and then 16 g of unreacted methyl alcohol were distilled from the reaction mixture obtained, yielding 112 g of a product containing 89.8% by mass of esters as a distillation residue. % of methyl fatty acids, 9.1 wt.% glycerin over 0.5% by weight of water. Then 112 g of the product from the transesterification process, 50 g of the isobutene fraction with the composition presented in Example 1 and 3 g of Amberlyst 35 catalyst were introduced into the autoclave with a capacity of 1000 ml. The mixture was heated at 90 ° C for 6 hours while stirring intensively. After cooling the contents of the reactor to room temperature, the excess of unreacted isobutene fraction was removed, and then the liquid, single-phase reaction product in the amount of 125.9 g was subjected to chromatographic analysis. The obtained product contained 83.1% by weight of fatty acid methyl esters, 11.9% by weight of glycerol tert-butyl di- and triethers, 0.5% by weight of glycerol tert-butyl ether, 0.1% by weight of glycerol, and 4.4% by weight masses of isobutene dimers. After distilling the isobutene dimers, a biofuel was obtained with the composition: 86.9 wt.%. fatty acid ethyl esters, 12.5 wt.% of glycerol tert-butyl di- and triethers, 0.5 wt.% % of glycerol tert-butyl monoether and 0.1 wt. glycerin. The biofuel was characterized by a kinematic viscosity at 20 ° C - 5.89 mm ² / s and a cetane number of -55.

PL 206 797 B1

Claims (2)

Patent claims 1. Process for the production of biofuel for compression ignition engines, containing as main components methyl or ethyl esters of fatty acids and tert-butyl or tert-amyl ethers of glycerol, by transesterification of triglycerides of fatty acids with methyl or ethyl alcohol in the presence of liquid or solid alkaline catalysts , characterized in that the reaction mixture obtained after transesterification, containing fatty acid methyl or ethyl esters, glycerin, unreacted alcohol and alkaline catalyst, is neutralized or the solid catalyst is removed and then the alcohol is separated from it, or the alcohol is first separated and then subjected to is neutralized or the solid catalyst is removed and the mixture is reacted with isobutene or isoamylenes in the presence of an acid catalyst. 2. The method according to p. A process according to claim 1, characterized in that the reaction mixture obtained after transesterification, after separation of unreacted alcohol and neutralization or removal of the alkaline catalyst, is reacted with isobutene or isoamylenes at a temperature of 50-110 ° C, for 1-10 hours, at a molar ratio of isobutene or isoamylenes to the glycerin 2-6: 1 contained in the mixture.