A kind of palladium-nickel series supported hydrogenation catalyst

Abstract

The invention relates to a Pd-Ni-series supported hydrogenation catalyst which contains palladium and nickel and a carrier mainly contains Al2O3. On the basis that the mass of the catalyst is 100%, the content of Pd is 0.02-0.6% and the content of Ni is 0.04-3%. The catalyst belongs to a double-metal alloy catalyst. In the invention, adverse influence due to surface tension and solvation effect of an impregnation solution on dispersion of palladium-nickel is overcome, so that the Pd-Ni alloy is easy to form in the catalyst, and the catalyst has excellent selectivity. The catalyst can be used in selective hydrogenation for C2, C3 and the like fractions, has excellent hydrogenation activity and selectivity and anti-coking performance, and especially has excellent anti-impurity interference capability, so that the catalyst is very suitable for C2 and C3 hydrogenation apparatuses being high in content of impurities, such as sulfur and arsenic.

Description

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

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

[0008] In recent years, due to the inferior quality of raw materials in some ethylene units, their C2 and C3 selective hydrogenation units contain certain impurities such as As and S, and bimetallic supported catalysts with Pd as the active component and Ag as the promoter are used in For this type of device, impurities such as As and S will affect the activity of the catalyst, and in severe cases, the catalyst will be deactivated, which will bring the risk of alkyne leakage in the device

At the same time, in the carbon dioxide hydrogenation device using the pre-hydrogenation process, the CO content is high and fluctuates greatly, which will also have a great impact on the activity of the bimetallic supported catalyst with Pd as the active component and Ag as the promoter.

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