Method of purifying ethylene through selective hydrogenation

Abstract

The invention relates to a method of purifying ethylene through selective hydrogenation. An adiabatic bed reactor for hydrogenation is arranged after an ethylene rectification column and before an ethylene polymerization reactor. A Pd-Cu-series catalyst is arranged in a fixed bed reactor and is prepared with an alumina-series carrier. During preparation of the catalyst, the alumina-series carrier is combined with a bipyridine derivative having a hydroxyl group, wherein a metal complex is formed from the hydroxyl bipyridine derivative combined on the carrier and an active component. Selectivity of the hydrogenation method is greatly better than that in a conventional hydrogenation method, ethylene loss is reduced, activity of the hydrogenation is excellent, the outlet content of acetylene is significantly lower than that with catalysts prepared through other two methods, and purity of ethylene is increased so that performance of a polymerization-grade ethylene product is improved well. Through reduction on green oil, active center of the catalyst is not covered by side product, so that the activity and the selectivity of the catalyst are maintained well, thereby prolonging the service life of the catalyst.

Description

Technical field [0001] The invention relates to a selective hydrogenation method, in particular to a selective hydrogenation refining method of ethylene. Background technique [0002] Polymer grade ethylene production is the leader of the petrochemical industry, and polymer grade ethylene and propylene are the most basic raw materials for downstream polymerization units. Among them, the selective hydrogenation of acetylene has an extremely important impact on the ethylene processing industry. In addition to ensuring that the acetylene content at the outlet of the hydrogenation reactor meets the standard, the selectivity of the catalyst is excellent, which can make ethylene generate as little ethane as possible, which is helpful for improving the entire process. The ethylene yield of the process is of great significance to improve the economic efficiency of the device. [0003] The pyrolysis C2 fraction contains 0.5%-2.5% mole fraction of acetylene. When producing polyethylene, a s...

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Problems solved by technology

Using this patented method, the carrier adsorbs a specific polymer compound through the chemical adsorption of the hydroxyl group of alumina and the polymer, and the amount of the polymer compound adsorbed by the carrier will be limited by the number of hydroxyl groups of alumina; the functionalized polymer and Pd The complexation effect is not strong, and sometimes the loading capacity of the active components does not meet the requirements, and some active components remain in the impregnation 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 complicated process flow

[0012] In the selective hydrogenation refining process of ethylene with high space velocity, the hydrogenation condition requires high catalyst activity, and the bimetallic supported catalyst with Pd as the active component and Ag as the promoter is used in this type of device. The reaction temperature is high, the activity cannot meet the requirements of the device well, and the disadvantage of leaking alkyne is prone to occur. It is necessary to choose a more suitable auxiliary agent to prepare the catalyst to meet the hydrogenation requirements of the device.

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