A kind of method for preparing propylene by catalytic cracking of n-butene

Abstract

The invention discloses a method of preparing propylene by catalytic cracking of n-butene. Under a catalytic cracking condition, a n-butene-containing raw material successively passes through an FER molecular sieve catalyst bed layer and a modified ZSM-5 molecular sieve catalyst bed layer, wherein the filling mass ratio of an FER molecular sieve catalyst and a modified ZSM-5 molecular sieve catalyst is (1:1) to (3:1); the catalytic cracking conditions are as follows: the reaction temperature is 450-550 DEG C, preferably 450-500 DEG C, the total pressure of the reaction is 0-0.5MPa, and the weight space velocity is 1-10 / h; and the modified ZSM-5 molecular sieve comprises the following components in percentages by weight: 4.5-6.0% of zirconium dioxide, 0.2-0.5% of iridium dioxide, 0.15-0.45% of SO4<2-> and the balance of ZSM-5 molecular sieve. The method in an industrial process of producing propylene from an n-butene-containing mixed C4 raw material has the advantages of low reaction temperature and high single-pass yield of propylene.

Description

technical field [0001] The invention relates to a method for preparing propylene from n-butene. Background technique [0002] In 2011, the total output of propylene in my country was 14.68 million tons. In 2011, the apparent consumption of propylene in my country was 16.43 million tons, and the self-sufficiency rate was only 89.3%. It is estimated that the apparent consumption of propylene in my country will reach 22 million tons in 2015. [0003] With the lightening of ethylene cracking raw materials and the impact of ethane cracking routes and methanol-to-olefins projects, in recent years, the output of ethylene cracking by-product propylene, which is the main source of propylene, will decrease year by year. On the other hand, the rapid development of the methanol-to-olefins project, and its by-product C4 has provided more n-butene resources for the market. Therefore, using cheap and abundant n-butene as raw material, converting n-butene into propylene through catalytic ...

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Problems solved by technology

[0013] The ZSM-5 molecular sieve catalyst adopted in the prior art scheme still has the deficiency that the single-pass yield of the target product propylene is low. Through the catalyst modification method described in the above-mentioned documents, the single-pass yield of propylene can be appropriately improved, but the propylene yield is still low. room for further improvement

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