Ex-situ pre-reduction and passivation treatment method for acetylene pre-hydrogenation catalyst

Abstract

The invention discloses an ex-situ pre-reduction and passivation treatment method for an acetylene pre-hydrogenation catalyst. The ex-situ pre-reduction and passivation treatment method comprises: (1)carrying out pre-reduction treatment on an oxidation-state hydrogenation catalyst using Pd and Ag as active components; and (2) carrying out passivation treatment on the pre-reduced hydrogenation catalyst, wherein the passivation process comprises: cooling to a passivation temperature of 30-50 DEG C under a normal pressure under nitrogen protection, introducing oxygen-containing gas with an oxygen molar concentration of 0.61-5.0%, carrying out passivation for 2.5-5.5 h, introducing air, and continuously carrying out passivation for 9-11 h. According to the present invention, the method has characteristics of simple operation, mild condition and good passivation effect, and the obtained product can stably exist in air, is conveniently stored and transported, is easily reduced by H2 in theraw material gas during the use, and can rapidly provide high activity and high selectivity so as to substantially shorten the start-up time and bring good economic benefits to enterprises.

Description

technical field [0001] The invention relates to an external pre-reduction and passivation treatment method of an acetylene pre-hydrogenation catalyst, in particular to an external pre-reduction and passivation treatment method of an acetylene pre-hydrogenation catalyst with Pd-Ag as an active component. Background technique [0002] The pyrolysis gas produced in the steam cracking process of petroleum hydrocarbons often contains a small amount of impurities such as acetylene, propyne (MA) and propadiene (PD), and their existence will affect the homogeneous polymerization and copolymerization processes used in subsequent sections to varying degrees. high-efficiency polyethylene and polypropylene catalysts. According to the requirements of post-processing procedures such as polyethylene, ethylene-propylene rubber, and polypropylene, the molar concentration of acetylene in polymer grade ethylene must be lower than 5ppm, and the molar concentration of acetylene in ethylene must ...

AI Technical Summary

Problems solved by technology

In industry, two methods are generally used to reduce the catalyst. One is to drive the catalyst directly in the oxidized state. While the hydrogenation reaction is going on, the hydrogen in the cracked gas is used for reduction. The advantage of this method is that it saves the additional catalyst preparation. The reduction process simplifies the process, but the disadvantage is that the initial activity is low, and the alkyne and CO in the cracked gas will affect the reduction of palladium oxide, and the reduction while reacting is easy to cause runaway temperature; the other is to first pass pure hydrogen to the catalyst. Internal in-situ reduction, and then feed the raw material gas for hydrogenation reaction. The advantage is that the catalyst is fully reduced and has high activity. The disadvantage is that reduction equipment needs to be added, and the reduction time is long, which affects the normal start-up.

Based on the advantages and disadvantages of the above two catalyst reduction methods, external pre-reduction is a good choice, but the activity of elemental palladium is very high, and it is easily oxidized in the air, which greatly affects its activity. In order to facilitate storage and transportation, the device Externally reduced catalysts need to be passivated

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