SU1066975A1 - Process for preparing olefins - Google Patents

Abstract

A method for producing olefins by selectively hydrogenating diene or acetylenic hydrocarbons in the presence of a supported catgie. based on a complex of palladium chloride with an amine at a temperature of 20-60 ° C and a hydrogen pressure of 0.510 atm, characterized in that, in order to simplify the process technology and reduce the consumption of the catalyst, a complex of palladium chloride with a symmetric tertiary aliphatic . tic amine of general formula (C p H2t + 1) s. 4-12, supported. on inorganic oxide n 5sitel selected from the group of: alumina, aluminosilicate, zeolite type. X, y, A.I.

Description

05

sg with | The invention relates to the production of single double bond unsaturated hydrocarbons by selectively hydrogenating conjugated diene and acetylenic hydrocarbons and can be used to produce cycloofinic compounds, such as cyclopentene, which is a valuable monomer for the production of synthetic rubbers, as well as for hydrotreating olefin oil from traces of diene and acetylenic hydrocarbons. A number of methods for the preparation of olefinic compounds are known by selectively hydrogenating the corresponding dienes or acetylenes in the presence of both homogeneous and heterogeneous catalysts based on Group VIII metals. Metals, their salts or oxides supported on inorganic carriers (alumina, magnesia, spinels, etc.) are used as heterogeneous catalysts. These catalysts are highly processable, which is associated with the ease of separation of the reaction products and the possibility of its subsequent regeneration. The disadvantages of heterogeneous catalysts include the relatively low selectivity of the process for the yield of olefins associated with the reaction at elevated temperatures and hydrogen pressure. In addition, heterogeneous catalysts are sensitive to various kinds of impurities (oxygen, moisture, sulfur-containing compounds, etc.). Various metal-complex compounds are used as homogeneous catalysts, either alone or in combination with reducing agents (sodium borohydride, aluminum hydride, organoaluminum compounds). When using homogeneous catalysts, mild conditions for carrying out the hydrogenation process (low temperature and hydrogen pressure), high selectivity in the yield of target products, and stability are provided. The disadvantages of homogeneous catalysts are the difficulty of separating the reaction products, the relatively low activity during the hydrogenation process, and the need to use in most cases scarce and fire-hazardous reducing agents. A method of producing olefins is known by selectively hydrogenating diene or acetylenic hydrocarbons in the presence of reduced dialkyl aluminum hydride of a palladium salt complex with octyl or butylamine, linear or cyclic sulfoxide, cetyl alcohol or polyethylene glycol. The process is carried out at room temperature and a hydrogen pressure of 0.45-10 atm. The selectivity of the reaction in the yield of olefins is high (95-99%) with almost complete conversion of the substrate. The activity of the catalysts is in the range of 30005000 mol of substrate / g-at Pd-aTM. The method has disadvantages that are characteristic of homogeneous catalysis processes. The closest to that proposed by technical accuracy is the method of producing olefins by selectively hydrogenating diene or acetylenic hydrocarbons in the presence of a catalyst, which is a complex of palladium chloride with modified aminopropyltriethoxysilane with silica gel. The catalyst acquires the catalytic activity of noc; ie, its treatment with sodium borohydride. The process is carried out at 0-150 ° C, preferably at 2050 ° C, and a hydrogen pressure of 0.1-50 atm. The catalyst can be reused. The process allows to obtain the corresponding olefins in a yield of 99%. The catalyst activity is 1000 mmol / g-at Pd atm 2. The disadvantages of the method are the complexity of the technology associated with the need to use a reducing agent, sodium borohydride, as well as a high consumption of catalyst caused by its low activity. The purpose of the invention is to simplify the process technology by eliminating the use of a flammable reducing agent and reducing the consumption of a catalyst containing palladium. This goal is achieved by the fact that according to the method of producing olefins by selective hydrogenation of diene or acetylenic hydrocarbons, in the presence of a supported catalyst based on a complex of palladium chloride with an amine at 20-60 ° C and a hydrogen pressure of 0.51 gO atm, the complex of chloride is used as a catalyst palladium with symmetric tertiary aliphatic amine of the general formula L (C „P2) C 12, deposited on an inorganic oxide carrier selected from the group of: alumina, aluminosilicate, type X, Y, A. Catali zeolite the mash has a high activity (up to 30,000 mol of the substrate / g – at Pd l atm H2P), high stability, which makes it possible to carry out a series of successive cycles of hydrogenation on the same sample. In addition, the catalysts do not lose activity after contact with atmospheric oxygen.

Hydrogenation of diene and acetylenic hydrocarbons is carried out at 20; 7bO ° C and a hydrogen pressure of 0.510 atm in a glass reactor such as a catalytic duck, or in a swinging autoclave with a number of oscillations of 200-400 ac / min in a hydrocarbon solvent;

The catalysts used are prepared as follows.

The interaction of palladium chloride with a tertiary aliphatic amine is carried out in an aromatic solvent at 30-C O and molar ratio amine / palladium is 0.2-10, preferably 0.5-4.0, in an argon atmosphere. The concentration, palladium salts are varied from 5-10 to 1 mol / l. Interaction time 5-20 44

Inorganic oxide carriers are prepared as follows.

A portion of the carrier is placed in a quartz reactor-type vacuum 2-6 h either at room temperature or with heating at 250400 ° C. as carriers, use y-alumina, aluminosilicate, zeolites of different nature of the type X, Y, A.

The palladium complexes are applied to the surface of the prepared carriers by chemisorption of solutions of the complexes either in vacuum or in an argon atmosphere. The concentration of palladium on the support varies from 0.05 to 5% by weight. It is preferable to use a low concentration of palladium, since with its high content on the carrier (.%) The specific activity of the catalysts decreases. After bleaching the complex solution, indicating the end of chemisorption, a substrate is introduced into the reactor and hydrogen is supplied.

Example 1. In a three-necked flask were placed 44.3 mg of palladium chloride, purged with argon, in a stream of argon 197.5 mg of trinonylamine (molar ratio 1: 2) and 20 m of toluene were introduced. The mixture is stirred at 18 hours. To the quartz reactor, 0.53 g-j-alumina is charged, which is activated by heating for 2.5 hours under vacuum (residual pressure of mercury), and 2.5 ml of toluene solution of the complex containing 2.5, -10 M1iol Pd and palladium concentration on the surface of the carrier 0.05 wt.%}. Then, 0.68 g (10 mmol) of isoprene is charged, hydrogen is fed (0.8 atm), and hydrogenation is carried out with vigorous stirring of the reaction mixture (the number of oscillations is 330 qu / min). Upon completion of the reaction, the catalyzate is separated, in

found, wt%: isoprene 2.7; 2-methyl butene-2, 47; 2-methylbutan-1 30.8; H-methyl butene-1 17.6; izo-. pentane 1.9. The selectivity of the hydrogenation reaction, which is calculated as the ratio of the sum of olefins to the sum of all reaction products, is 98%. The catalyst activity is 26800 mol of isoprene / g-at Pd atm H2-h.

Example 2. A palladium complex is synthesized according to the procedure of Example 1 using tributylamine as an tertiary amine in the amount of 92.5 mg. The reactor is charged with 0.55 g of j-alumina, heated under vacuum for 3 hours, and 5 ml of a toluene solution of a coglex containing mol of Pd (concentration of palladium on the surface of the carrier

Q 0.1 wt.%). Load 0.75 g

(11.5 mmol) of cyclopentadiene, hydrogen is fed in and hydrogenated at 40 ° C. At the end of the reaction, the following are found in the catalyzate, wt%: cyclophen5 ten 94.5; cyclopentane 1.5; cyclopentadiene 4. Selectivity 98.4%, catalyst activity 24,000 mol of cyclopentadiene / g-at Pd-aTM H2-h.

Example 3. Synthesize the complex according to the method of example 1 using as a tertiary amine tridodecylamine in the amount of 260.5 mg. 0.53 g of y-alumina is loaded into the reactor, pumped out at 20 ° C and 10 ml of a toluene solution of the complex containing

0.25 mmol Pd (palladium concentration on the surface of the carrier is 5% by weight). 0.68 g of isoprene is charged, hydrogen is introduced (0.5 atm.), And hydrogenation is carried out at 20 ° C. Catalysation, flow,% by weight: isoprene 13.9; 2-methyl, butene 2 31.9; 2-methylbutene-1 29.4;, W-methylbutene-1 24.8. Selectivity 100%. Catalyst activity

5 5000 mol of isoprene / g-at.

Examples 4-13. The catalyst preparation process is carried out as described in Example 1, using as a tertiary gmina

0 trioctylamine. The hydrogenation reaction is carried out in a duck type reactor, in example 10, in an autoclave. The conditions and results of the hydrogenation are shown in the table.

5 As can be seen from the presented data, the method allows to significantly simplify the process technology by eliminating the catalyst reduction, as well as reducing

0 the consumption of precious metal, which is part of the catcher, due to the increased activity of the catalytic composition with a high selectivity for the yield of olefins.

Claims (1)

METHOD FOR PRODUCING OLEFINS by selective hydrogenation of diene or acetylene hydrocarbons in the presence of a supported catalyst on. based on a complex of palladium chloride with amine at a temperature of 20-60 ° C and a hydrogen pressure of 0.510 atm, characterized in that, in order to simplify the process technology and reduce catalyst consumption, a complex of palladium chloride with a symmetric tertiary aliph is used as the latter. with an amine amine of the general formula S (, C _h Н _{2п + 1} ) ₃ , ^{where n} ®.4-12, supported,. to an inorganic oxide and <3site selected from the group: aluminum oxide, aluminosilicate, type zeolite. X, Ϊ »A. § fe ίσ> CO <1 SP t