A kind of palladium-gold series supported hydrogenation catalyst

Abstract

The invention relates to a palladium-gold-based supported hydrogenation catalyst. The catalyst contains palladium and gold, and the carrier mainly contains Al2O3. It is 0.02~0.25%. The catalyst is an alloy type bimetallic catalyst. Since the adverse effects of the surface tension of the impregnating liquid and the solvation effect on the dispersion of palladium-gold are overcome in the preparation method, the prepared catalyst is more conducive to the formation of palladium-gold alloy , the catalyst has excellent selectivity. The catalyst of the invention can be used in the selective hydrogenation process of fractions such as C2 and C3, and has good hydrogenation activity, excellent selectivity and good anti-coking performance; meanwhile, it brings relatively high increment of ethylene and propylene.

Description

technical field [0001] The invention relates to a hydrogenation catalyst, in particular to a palladium-gold series supported hydrogenation catalyst. Background technique [0002] Ethylene is one of the most important basic raw materials in the petrochemical industry. As a monomer for the synthesis of various polymers - ethylene, most of it is produced from petroleum hydrocarbons (such as ethane, propane, butane, naphtha and light diesel oil, etc.) Cracked in the system. The ethylene-based C2 fraction obtained by this method also contains 0.5% to 2.5% (mole fraction) of acetylene. The presence of acetylene will complicate the polymerization process of ethylene and deteriorate the polymer properties. When polyethylene is produced by high-pressure method, there is a danger of explosion due to the accumulation of acetylene; in addition, when polyethylene is produced, the presence of acetylene will also reduce the activity of the polymerization catalyst and increase the consump...

AI Technical Summary

Problems solved by technology

This method has the following disadvantages: (1) affected by the pore structure of the carrier, the dispersion of active components cannot be precisely controlled, and the randomness is strong

(2) Affected by the surface tension of the immersion liquid and the solvation effect, the precursor of the metal active component is deposited on the surface of the carrier in the form of aggregates, which cannot form a uniform distribution

(3) Carbon dihydrogenation requires high catalyst selectivity. The interaction between the additive Ag and the active component Pd is the key factor to improve the catalyst selectivity. The catalyst prepared by the traditional method, due to the different surface tension of the Pd and Ag solutions , Pd and Ag cannot be distributed in the same layer, and the additive effect of Ag is not obvious. It is necessary to increase the amount of Ag to promote the role of the additive, which will hinder the transfer of hydrogen and cause the oligomerization reaction to occur. The possibility increases, the amount of green oil generation increases, and the life of the catalyst is affected

Using this patented method, the carrier adsorbs a specific polymer compound, and chemically adsorbs the polymer through the hydroxyl group of alumina. The amount of polymer compound adsorbed by the carrier will be limited by the number of hydroxyl groups of alumina; The complexation effect of the catalyst is not strong, and sometimes the loading capacity of the active components does not meet the requirements, and some active components remain in the impregnating solution, resulting in an increase in the cost of the catalyst; the preparation of carbon dioxide hydrogenation catalysts by this method also has the disadvantage of complex process flow

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