Catalytic cracking method for producing propylene

Abstract

The invention discloses a catalytic cracking method for producing propylene, comprising the following steps: contacting heavy feed stock with a first stream of a catalyst containing shape-selective zeolite with an average pore size being less than 0.7nm in a first riser reactor to conduct cracking reaction, then separating the oiling agent, introducing oil gas into a product separation system, and introducing the catalyst into a stripper or a fluidized bed reactor; contacting the recycled cracking heavy oil with a second stream of the catalyst containing shape-selective zeolite with an average pore size being less than 0.7nm in a second riser reactor to conduct cracking reaction, then letting the obtained oiling agent mixture and the light hydrocarbon introduced into the second riser reactor be subject to contact reaction, then introducing the reaction mixture into a fluidized bed combined reactor for reacting, introducing the reacted oil gas into the product separation system, and introducing the reacted catalyst into the stripper. According to the invention, the method is used for heavy oil catalytic cracking, the heavy oil conversion rate is high, the yields of propylene and butene are high, and the selectivity of dry gas and coke is good.

Description

technical field [0001] The present invention relates to a catalytic cracking method, and more particularly to a method for producing propylene by catalytic cracking of heavy raw materials. Background technique [0002] Catalytic cracking of heavy oil is an important method for the preparation of small molecule olefins such as ethylene, propylene and butene. Industrially used heavy oil catalytic cracking methods to produce light olefins include catalytic cracking technology for maximum production of propylene and catalytic thermal cracking technology for maximum production of ethylene. These two methods use a single riser reactor or a combination of single riser reactors The reactor structure of the fluidized bed cooperates with a special catalyst to react at a higher temperature. The above two methods can produce more low-carbon olefins such as propylene and ethylene, but the dry gas and coke yields are relatively high, and the propylene yield is difficult to further increa...

AI Technical Summary

Problems solved by technology

[0008] The technical problem to be solved in the present invention is to provide a catalytic cracking method for producing propylene that can increase the yield of propylene and has low dry gas selectivity in view of the shortcomings of the existing catalytic cracking method for producing propylene

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