The method of preparation of palladium catalyst

 

(57) Abstract:

The invention relates to the field of gas-phase purification of ethane-ethylene fraction of pyrogas from acetylene impurities, in particular to a method of preparation of the catalyst purification method for selective hydrogenation. The catalyst is prepared by impregnation of the alumina carrier with a solution of an amine complex of palladium mixed with polyethylene oxide and cesium carbonate at 68-70C, followed by drying. The technical result is to simplify the process and create a catalyst with high selectivity at low temperature hydrogenation. table 1.

The invention relates to the field of gas-phase purification of ethane-ethylene fraction of pyrogas from acetylene impurities, in particular to methods for preparing catalysts for purification by the method of selective hydrogenation.

A method of obtaining a palladium catalyst on the carrier for selective hydrogenation of acetylene to ethane-ethylene fraction containing 0.005 to 0.05 wt. % Pd on Al2O3by impregnation of the pre-calcined at 600-800oC carrier with a solution of barium nitrate, Ba(NO3)2drying for 4 h at 120oC, calcination at 800-850oC, impregnation treated node [1] . This catalyst at a temperature of 70oC, space velocity of the gas mixture 3000-9000 h-1acetylene contained in a quantity of 0.8 vol.%, hereroense completely. The disadvantages of this method are the low mechanical strength, short time (0.5-1 year), the formation of green oil.

The closest technical solution proposed is a method for preparing a catalyst for selective hydrogenation of acetylene to ethane-ethylene fraction (EAF) which contains the root of Al2O3coated with palladium and chromium, and the components are contained in amounts of 0.001-5% (preferably 0.01 to 0.5 percent) of palladium, of 0.001-5% (preferably 0.01 to 0.5 percent) chromium-alumina rest [2]. The method of preparation of palladium catalyst for selective hydrogenation of acetylene in EAF includes the stage of obtaining a mixture of solutions of salts of palladium nitrate and chromium nitrate, which is used as a modifier, impregnation obtained mixed solution of the carrier of aluminum oxide with a specific surface area of 1.5-5.0 m2/g, drying the impregnated carrier at temperatures 25-200oC either in open air or under vacuum, calcination at 700-900oC and treatment with hydrogen to move okay this way, provides selectivity 75-78%, the activity of 80% at a pressure of 3.4-34 MPa, a temperature of 50-200oC and flow rate of the source gas mixture 50-10000 h-1.

The disadvantages of this method of preparation of the palladium catalyst are using toxic element chromium as a modifier catalyst, energy-intensive stages of drying and calcining of the catalyst, obtaining a catalyst with low selectivity, operating at relatively high temperatures at which the formation of "green oil" due to the polymerization of acetylene and ethylene on the active centers.

The objective of the invention is to provide such a method of preparation of palladium catalyst on alumina carrier for the cleaning process AAF from acetylene by the method of selective hydrogenation, which reduces the number of stages of preparation of the catalyst, with the exception of the use of toxic chromium and energy-intensive stages of drying and baking, as well as to obtain a catalyst with high selectivity at low temperature hydrogenation and prevent the formation of "green oil".

The problem is solved by the proposed method obtained the effect of palladium catalyst on an alumina basis includes the stage of obtaining an aqueous solution of amine complex of palladium with polyethylene oxide and modifying additive cesium carbonate, impregnation of the carrier of Al2O3(with a specific surface area of 0.5-1.0 m2/g) obtained by the solution at 68-70oC, drying for 1-2 h at 90-100oC and calcining in air for 2-3 hours at 120-130oC and 4-5 hours at 140-145oC.

The resulting catalyst contains, wt%: palladium 0,01-0,5; cesium 0,01-0,5; -aluminum oxide - rest.

The proposed method of preparation of the palladium catalyst is different from the known fact that as palladium solution for impregnation of alumina media use a solution of amine complex of palladium mixed with polyethylene oxide as modifying additives used cesium carbonate and the impregnation process is carried out at a temperature of 68-70oC. It eliminates the use of energy-intensive stages, and produces a catalyst with high selectivity and operating at low temperatures.

The invention is illustrated by the following examples.

Example 1.

To 1.26 g PlCl2poured 15 ml ethanolamine, mix thoroughly until the salt is completely dissolved in ethanolamine at 70oC, poured 220 ml of an aqueous solution of polyethylene oxide as a surfactant containing 1,95 g Cs2CO3heat is preheated to 70oC for 1.2 hours at 70oC, then dried catalyst for 1.2 hours at 100oC, calcined for 3 h at 120oC and 5 h at 145oC.

Get the catalyst composition, wt.%: palladium 0.1; cesium 0,1; -alumina rest.

Example 2.

The catalyst is prepared analogously to example 1, except that the content of cesium carbonate in an impregnating solution is 0,975 g, and the temperature of the impregnation 68oC.

Get the catalyst composition, wt.%: palladium 0.1; cesium 0,05; -alumina rest.

The results of the tests of the catalysts according to the invention in the process of hydrogenation of acetylene in AEP presented in the table.

The test catalysts were carried out in pilot plant flow type. In the reactor of the pilot installation was downloaded 800 cm3sample catalyst. The system gave the original gas mixture EEF with hydrogen composition, vol.%: C2H20,3; C2H455; C2H640; CH40,4; H20,88; C3H6and C3H8the rest of it.

Every four hours, samples were taken of the contact gas analysis on the content of the acetylene. Analysis was performed on the chromatograph Color-102" with a flame was initationpirates in the range of 40-70oC, the volumetric rate of gas supply - 1500-3750 h-1.

The test results showed that the selective hydrogenation of acetylene in EAF on the catalyst prepared according to the proposed method is higher than the catalyst prepared by the method [2], 83-85% against 75-78% under the same conditions of the hydrogenation process, the temperature interval hydrogenation of acetylene in admixture eat for catalyst according to the invention are already lower than for the catalyst according to the method of [2] , 40-70oC against 50-200oC, and therefore the catalyst according to the proposed method of preparation was not observed the formation of "green oil".

Sources of information

1. A. c. USSR N 871377, publ. 1992 class B 01 J 23/44.

2. Pat. USA N 4551443, publ. 1985.

The method of preparation of palladium catalyst on alumina carrier for selective hydrogenation of acetylene to ethane-ethylene fraction by impregnation of the alumina carrier palladium solution with modifying additive, followed by drying, characterized in that as palladium solution using a solution of amine palladium complex in a mixture with polyethylene oxide as a modifying additive skin

 

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