Preparation method of high-coking resistance selective-hydrogenation catalyst

Abstract

The invention discloses a preparation method of a high-coking resistance selective-hydrogenation catalyst. The high-coking resistance selective-hydrogenation catalyst utilizes carriers which mainly comprise alumina, have bimodal hole distributed structures and contain double active components of Pd and Ni. In catalyst preparation, the coking resistant ingredient Ni in a form of microemulsion enters into a large hole of the carrier and the active ingredient Pd is mainly distributed on the carrier surface and especially in a small hole of the carrier. The coking resistant ingredient Ni is mainly distributed in the large hole of the carrier so that a catalyst surface coking degree is greatly reduced and the hydrogenated saturated compound can be gradually diffused out of the catalyst channels and thus channel blocking is avoided and a catalyst service life is greatly prolonged. The high-coking resistance selective-hydrogenation catalyst is especially suitable for C2 and C3 fraction hydrogenation, obviously reduces a green oil generation amount and catalyst coking, prolongs a catalyst service life and improves economic benefits of device operation.

Description

technical field [0001] The invention relates to a method for preparing a hydrogenation catalyst, in particular to a method for preparing a highly coking-resistant selective hydrogenation catalyst. Background technique [0002] Ethylene is one of the most important basic raw materials in the petrochemical industry. As a monomer ethylene for the synthesis of various polymers, most of it is steam cracked by petroleum hydrocarbons (such as ethane, propane, butane, naphtha and light diesel oil, etc.) be made of. The ethylene-based C2 fraction obtained by this method contains 0.5% to 2.3% (mol fraction) of acetylene. The existence of a small amount of acetylene in ethylene will complicate the polymerization process of ethylene and deteriorate the polymer properties. Reduce the activity of the polymerization catalyst and increase the consumption of the catalyst. Therefore, the content of acetylene in ethylene must be reduced below a certain value before it can be used as a monom...

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Problems solved by technology

ZL200810223451.6, proposed a method using a dual-pore carrier, which can provide the ability of the catalyst to accommodate macromolecular by-products, but cannot prevent the macromolecules that have already been generated from continuing to polymerize

[0009] In carbon two hydrogenation reaction, the generation of green oil and the coking of the catalyst are important factors affecting the reaction life of the catalyst. The activity, selectivity and service life of the catalyst constitute the overall performance of the catalyst. However, it has not solved the problem that the catalyst is easy to coke, or it has solved the problem that the catalyst is easy to generate green oil and coke, but it has not solved the problem of selectivity.

Although the carrier with a macroporous structure can improve the selectivity, the larger molecules generated by the polymerization and chain growth reactions tend to accumulate in the macropores of the carrier, causing coking and deactivation of the catalyst and affecting the service life of the catalyst.

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