Catalytic cracking method and catalytic cracking device for producing propylene

Abstract

The invention discloses a catalytic cracking method and a catalytic cracking device for producing propylene. The catalytic cracking method comprises the following steps that one or more heavy raw materials and a first catalytic cracking catalyst containing Y-type zeolite as a main active component undergo a contact reaction in a first riser reactor; after the contact reaction, the first catalytic cracking catalyst is subjected to steam stripping and regeneration and then is recycled; one or more light hydrocarbons and a second catalytic cracking catalyst having a temperature of 550 to 690 DEG C and containing a main active component of shape-selective zeolite having aperture sizes less than 0.7nm undergo a contact reaction in a second riser reactor; after the contact reaction, the second catalytic cracking catalyst is introduced into a fluidized bed reactor connected to the second riser reactor in series and undergoes a reaction; and after the contact reaction, the second catalytic cracking catalyst is subjected to steam stripping and regeneration and then is recycled. The catalytic cracking device adopts the configuration of a combined reactor composed of two risers and a fluidized bed. A stripper of the catalytic cracking device is divided into two independent stripping zones by a separator plate arranged in the stripper and a heat collector for cooling the regenerated second catalytic cracking catalyst is arranged in the stripper. The catalytic cracking method has a high propylene yield. The catalytic cracking device can realize a reaction and regeneration in a reaction device by two catalysts and has a simple structure.

Description

Technical field [0001] The invention relates to a catalytic cracking method and device for producing propylene. Background technique [0002] Catalytic cracking of heavy oil is an important method for the production of small molecular olefins such as ethylene, propylene and butene. The industrially used methods for the production of low-carbon olefins by catalytic cracking of heavy oil include catalytic cracking technology (DCC, USP4980053 and USP5670037) and Catalytic thermal cracking technology (CPP, USP6210562) for mass production of ethylene. These two methods use a single riser reactor or a single riser reactor combined with a dense fluidized bed reactor structure and a special catalyst to perform under higher temperature conditions reaction. The catalysts used in the above-mentioned two existing patented technologies are both a single catalyst system composed of active components such as medium pore zeolite (such as ZSM-5) and / or large pore zeolite (such as Y zeolite) cont...

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Problems solved by technology

Although this method has better flexibility, this method also has other defects that are difficult to overcome except that the rate of increase in the yield of small molecular olefins is relatively small: the first is that it is difficult to achieve when adding too little additive containing ZSM-5 zeolite. High production of small molecule olefins is required; second, when the additive containing ZSM-5 zeolite is higher, there is an obvious unfavorable physical dilution effect on the main catalytic cracking catalyst, thereby reducing the overall effect of the entire catalyst system, and there are still problems that cannot Neglect, the problem of matching the performance between the additional promoter and the main catalyst

Yet this method propylene productive rate is not high, and does not involve the structure of reaction device

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