Selective hydrogenation method

Abstract

The invention provides a selective hydrogenation method, which adopts a fixed bed reactor, wherein the reactor is filled with a hydrogenation catalyst which has a bimodal pore distribution structure and at least contains Pd, W, Ni and Cu, pyrolysis gasoline and hydrogen are mixed and preheated and then enter the reactor, and the hydrogenation process conditions are that the reaction temperature is 30-120 DEG C, the reaction pressure is 2-6 MPa, the air speed is 0.5-4 h<-1>, and the volume ratio of hydrogen to oil is (100-600):1. According to the invention, a catalyst carrier used in the hydrogenation method is alumina or mainly alumina and has a bimodal pore distribution structure, active components of the catalyst at least contain Pd, W, Ni and Cu, and the hydrogenation method is characterized in that Ni and Cu are loaded in a microemulsion manner, so that Ni and Cu are mainly distributed in the macropores of the carrier; W is loaded by a solution method, Pd is loaded by a solution method and a microemulsion method, most of Pd is loaded by the solution method, and a small part of Pd is loaded by the microemulsion method; and the hydrogenation method has the characteristics of high hydrogenation activity, good selectivity and strong operation stability.

Description

technical field [0001] The invention relates to a selective hydrogenation method, in particular to a selective hydrogenation method for pyrolysis gasoline fractions. Background technique [0002] Pyrolysis gasoline is an important by-product of steam cracking ethylene plant, and its output is 50%-80% (mass fraction) of the ethylene production capacity. The content of aromatics is as high as 50%, and it is an important raw material for extracting aromatics. Pyrolysis gasoline also contains a large amount of unsaturated hydrocarbons (dienes, monoenes) and impurities such as sulfur and nitrogen, resulting in poor stability of pyrolysis gasoline and the formation of colloids, and these unsaturated hydrocarbons and impurities such as sulfur and nitrogen will increase significantly Reducing the selectivity of the extractant when extracting aromatics seriously affects the purity and color of aromatics products. Therefore, pyrolysis gasoline must be hydrotreated to remove impurities...

AI Technical Summary

Problems solved by technology

[0019] The reduction temperature of Ni often reaches about 450°C. At this temperature, Pd atoms in the reduced state are easy to aggregate, which greatly reduces the activity of the catalyst. It is necessary to increase the active component to compensate for the loss of activity, but it will cause selection decline of sex

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