Catalytic conversion method for preparing lower olefins and aromatics

Abstract

The invention relates to a catalytic conversion method for preparing lower olefins and aromatics. Raw oil with different cracking performances enters different reaction zones of a first riser reactor to contact with a catalytic cracking catalyst for cracking reaction to separate a spent catalyst from reaction oil gas, wherein the reaction oil gas is separated to obtain a product containing lower olefins, gasoline, distillates with distillation range of 180-250 DEG C and catalytic wax oil, wherein the gasoline is extracted by light aromatics to obtain light aromatics and gasoline raffinate; the raw materials are cracked to be sent into a second riser reactor to contract with a hot regenerated catalyst for catalytic conversion; and the spent catalysts of the two riser reactors are burned and regenerated in the same one regenerator and then returns to the two riser reactors. The method uses heavy raw materials to furthest produce the lower olefins, such as propylene, ethylene, and the like, particularly the propylene, the production rate can exceed 40 wt%, and at the same time the method can coproduce the aromatics, such as toluene, xylene, and the like.

Description

technical field [0001] The invention belongs to the catalytic conversion method of hydrocarbons in the absence of hydrogen, more specifically, it is a method for converting heavy raw materials into low-carbon olefins rich in propylene and ethylene and aromatics rich in toluene and xylene method. Background technique [0002] Low-carbon olefins such as ethylene and propylene are important organic chemical raw materials, among which propylene is a synthetic monomer for products such as polypropylene and acrylonitrile. With the rapid growth of demand for derivatives such as polypropylene, the demand for propylene is also increasing year by year. The demand in the world propylene market has increased from 15.2 million tons 20 years ago to 51.2 million tons in 2000, with an average annual growth rate of 6.3%. It is estimated that the demand for propylene will reach 86 million tons by 2010, with an average annual growth rate of about 5.6%. [0003] The methods for producing pro...

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Problems solved by technology

[0012] The above prior art still has deficiencies in the design of alkane molecular cracking reactions. At the same time, the product distribution of the prior art is cut according to the conventional FCC fractionation system, and the potential content of aromatics and low-carbon olefins in gasoline or diesel oil is not fully utilized. , resulting in low yields of propylene and aromatics

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