RO129990A0 - Hydrotalcite-based catalyst for hydrogenation of fatty acid esters and process for preparing the same - Google Patents

Abstract

The invention relates to a catalyst and to a process for preparing the same. According to the invention, the catalyst comprises 0.7% Ru and 1.4% Sn on a hydrotalcite support. The process, as claimed by the invention, consists in successively impregnating a hydrotalcite support of the type Mg-Al-COhaving a Mg:Al ratio of 2:1, in the presence of bentonite, with 0.1...1.1% Ru and, after drying, with 0.2...2.2% Sn, at a volume rate of the impregnation solutions of 0.2...1.9 h, followed by calcination at a temperature of 350...500°C, activation by treatment with an aqueous solution of sodium borohydride in excess of 5...90% and in a hydrogen flow, at a temperature of 250...550°, for 3...12 h.

Description

HYDROGENATION CATALYST OF BASIC FATTY ACID ESTERS

FOR HYDROTALCITES AND THE PROCESS FOR OBTAINING THIS

The invention relates to a hydrogenation catalyst for fatty acid esters based on hydrotalcite and to the process for obtaining it.

Numerous processes are known for obtaining fatty alcohols by hydrogenation of fatty acid esters.

US Patent 8,426,654 discloses a process for the production of fatty alcohols by hydrogenation of the wax-type esters at 180-220 ° C and 70 to 100 bar, in a fixed layer of granulated catalyst, obtained by extrusion, containing principal components such as copper and oxide copper-chromium and secondary components such as zinc, aluminum, iron, silicon and alkaline earth elements. The process has disadvantages related to the use of toxic metals such as chromium in obtaining the catalyst.

CN Patent 101733124 describes a method for obtaining in a continuous system and a fixed layer of fatty alcohols on a catalyst based on copper and zinc as active components and one or more metals of manganese, barium or zirconium are used as co-catalysts, and silicon and aluminum are used as structural promoters. The content of the active components is from 40 to 95% by mass; the content of cocatalysts is from 1 to 30% by mass, and the content of promoter structure is 0.01 to 50% by mass. The catalyst exhibits high activity and high selectivity in fatty alcohols, long service life and the ability to catalyze the hydrogenation reaction at a relatively low pressure. The process has disadvantages related to the high content of heavy metals.

CN Patent 102476056 describes a catalyst used in the production of fatty alcohols composed of a mixture of zinc oxide and copper oxide at 18-66% content, from one or two metals selected from manganese oxide and nickel oxide at concentration of 0-40%, of alumina at the concentration of 5-17% and 0-45% support which is either diatomite or calcium carbonate. The catalyst has high activity and also good stability. The preparation method is simple, has high operability and is easy to industrialize.

The process has disadvantages related to the use of a high content of heavy metals in the preparation of the catalyst.

US Patent 5,043,485 discloses a process for the production of fatty alcohols by catalytic hydrogenation of mixtures of fatty acid methyl esters, at a pressure of 100 to 300 bar, at temperatures from 160 ° to 270 ° C and at a hydrogen / ester molar ratio. fatty acid methyls from 10: 1 to 500: 1. The reaction is carried out on a catalyst which

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contains 30-40% gr. copper, between 23 to 30% gr. chrome, from 1 to 10% gr. manganese, from 1 to 10% gr. silicon and from 1 to 7% wt. barium. After calcination the catalyst is granulated with 1 to 10% wt. graphite-activated binder with hydrogen or a mixture of gases containing hydrogen. This process allows the production of fatty alcohols, with high yields of mixtures of methyl esters of fatty acids containing fatty acid residues from C8 to C22. The process has disadvantages related to the use in obtaining the catalyst of toxic metals such as chromium.

US Patent 5,124,491 discloses a process for the production of fatty alcohols by catalytic hydrogenation of fatty acid methyl esters at pressures from 20 to 100 bar and at temperatures from 160 ° to 270 ° C, in molar ratio hydrogen / methyl esters of fatty acids from 10: 1 to 500: 1. The reaction is carried out on catalysts containing 30-40% by weight copper, between 23 and 30% wt. chrome, from 1 to 10% gr. manganese, from 1 to 10% gr. silicon and from 1 to 7% wt. barium and other transition metals in the form of oxides. The process has disadvantages related to the use in obtaining the catalyst of toxic metals such as chromium.

US Patent 5,364,986 discloses a process for the production of C8-22 fatty alcohols which consists of catalytic hydrogenation of triglycerides with hydrogen in the presence of a copper-zinc catalyst. The pressure in the reaction zone is from about 200 .... 280 bar, the temperature from 200 ° C to 230 ° C and the output temperature of the reaction zone from about 190 ° C to about 220 ° C. The process has the disadvantage generated by the high value of the hydrogenation pressure.

It is known that the main process for the production of fatty alcohols is the catalytic hydrogenation of fatty acid esters, preferably fatty acid methyl esters. Carrying out the process in a continuous system and a fixed catalytic layer requires the use of a catalyst in granular form. The catalysts commonly used also hydrogenate the olefinic bonds of the unsaturated fatty acid chains with the formation of saturated fatty alcohols with higher melting point and more difficult to handle.

The technical problem solved by the invention relates to a selective hydrogenation catalyst for fatty acid esters in unsaturated fatty alcohols, based on Ru and Sn deposited on granulated hydrotalcite and a process for obtaining it.

The process according to the invention removes the aforementioned disadvantages by the fact that in the preparation of the catalyst no environmentally friendly metals such as chromium are used and the metal content is reduced. Also the operating pressure has relatively low values.

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The invention has the following advantages:

a. The non-environmentally friendly metals are eliminated from the composition of the fatty acid ester hydrogenation catalyst;

b. The catalytic support used is a hydrotalcite and does not pose problems of environmental pollution during preparation and after exhausting the catalyst;

c. The method of deposition of the active metals on the catalytic support is obtained by the incipient wetting of the granulated catalytic support with catalytic precursors, so that the process does not result in water loaded with heavy metals or toxic by-products;

d. The hydrogenation process of fatty acid esters in fatty alcohols in the presence of this catalyst proceeds with the protection of the olefinic bonds, allowing the manufacture of unsaturated fatty alcohols with improved flow characteristics at low temperatures.

The proposed hydrogenation catalyst for hydrogenation of fatty acid esters to fatty alcohols, according to the invention, eliminates the mentioned disadvantages by being prepared by successive impregnation by the method of incipient wetting of the Mg-Al-CC> 3 hydrotalcite base having a Mg ratio. : Al of 2: 1, granulated in the presence of bentonite, with Ru at a concentration of 0.1 .... 1.1% and, after drying, with Sn at a concentration of 0.2 .... 2, 2% compared to the catalytic support, at a volumetric speed of the impregnation solutions of 0,2 ... 1,9 h ' ¹ , followed by calcination at 350 ... 500 ° C, activation by treatment with aqueous solution of borohydride of sodium to an excess of 5 ... 90% compared to the required stoichiometric quantity and in hydrogen current at 25O ... 55O ° C for a duration of 3 ... 12 h. The process of hydrogenation of fatty acid esters on The catalyst prepared according to claim 1, is characterized in that it is made in a fixed layer catalytic at a temperature of 200 ... 340 ° C, a pressure of 10 ... 150 atm, the volume velocity of the methyl oleate 0.1 .. .0,8 h ' ¹ , molar ratio H2 / methyl oleate 5. .20.

Example of embodiment of the invention:

a. Mg-Al-CCh hydrotalcite having a Mg: Al ratio of 2: 1 was prepared by co-precipitating at room temperature with a solution of 250 g Mg (NO3) 2 ^- 6H2O and 121.95 g A1 (NO ₃ ) 3 dissolve in 1170 g bidistilled water by adding a solution containing 88.66 g NaOH and 73.52 g Na2CO3 dissolved in 520 g bidistilled water at a pH of 10, then aged for 3 h at 60 ° C, then filtered. , washed with distilled water until the pH of the washing water shows the value 7, dried at 105 ° C for 12 h, calcined at 460 ° C for 5 h, then hydrated with ultrapure water and allowed to stand at room temperature. the chamber for 12 h, then filtered and dried at 105 ° C for 12 h.

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b. The granulation of hydrotalcite was achieved by mixing in the presence of bentonite at a hydrotalcite / bentonite volumetric ratio of 6: 4 in the presence of distilled water at a water / solid ratio of 2/5, followed by extrusion and drying at 120 ° C. for 8 hours.

c. Preparation of the catalyst 0.7% Ru + 1.4% Sn / hydrotalcite was performed by successive impregnation, followed by drying at 120 ° C for 4 h with aqueous solutions of RuCR and SnCl ₂ by the method of initial wetting at a volume speed. identical of the impregnation solutions of 1.5 h ' ¹ , followed by calcination at 400 ° C for 8 h. The concentration of the acid centers determined by the thermodorption of diethylamine was as follows: i) the strong acid centers 0.19 meq / g, ii) acid centers of average strength 0.28 meq / g, iii) weak acid centers 0.15 meq / g. The catalyst was activated in 2 stages: i) in the first stage by treatment with aqueous solution of 10% sodium borohydride at an excess of 20% compared to the required stoichiometric quantity, ii) in step 2 in hydrogen current at 35 ° C. C for 5 hours.

d. Testing of the catalyst 0.7% Ru + 1.4% Sn / hydrotalcite in the hydrogenation process of the methyl oleate was carried out in a fixed catalytic layer in two operating variants: a) temperature of 240 ° C, pressure of 100 atm, the volumetric velocity of the methyl oleate 0.12 h ' ¹ , molar ratio H2 / methyl oleate 10, the conversion of the methyl oleate being 87.8%, the yield in oleic alcohol of 50.6%, and the yield in hydrocarbons of 15, 5%; b) temperature of 240 ° C, pressure of 40 atm, volume velocity of methyl oleate 0.12 h ' ¹ , molar ratio H ₂ / methyl oleate 10, conversion of methyl oleate being 71.4%, yield in alcohol 17.3% oleic oil and 48.1% hydrocarbon yield.

Claims (2)

1. Catalyst for selective hydrogenation of fatty acid esters in fatty alcohols, characterized in that it is prepared by successive impregnation by the method of incipient wetting of the Mg-Al-CCh type hydrotalcite support having a Mg: Al ratio of 2: 1 , granulated in the presence of bentonite, with Ru at a concentration of 0.1 .... 1.1% and, after drying, with Sn at a concentration of 0.2 .... 2.2% compared to the catalytic support , at a volumetric rate of impregnation solutions of 0.2 ... 1.9 h ' ¹ , followed by calcination at 35O ... 5OO ° C, activation by treatment with aqueous sodium borohydride solution at an excess of 5 ... 90% compared to the stoichiometric quantity required and in hydrogen current at the temperature of 25O ... 55 ° C for 3 to 12 hours. 2. A process for hydrogenating fatty acid esters on the catalyst prepared according to claim 1, characterized in that it is carried out in a fixed catalytic layer at the temperature of 200 ... 340 ° C, pressure 10 ... 150 atm, volume velocity of methyl oleate 0.1 ... 0,8 h ' ¹ , molar ratio H ₂ / methyl oleate 5 ... 20.