Catalytic conversion method for preparing propylene and aromatic hydrocarbons

Abstract

A catalytic conversion method for preparing propylene and aromatic hydrocarbons comprises the following steps: hydrocarbon raw materials with different cracking performances are contacted with a catalytic cracking catalyst to carry out cracking reaction in a fluidized-bed reactor under the conditions that the temperature is 450-750 DEG C, the weight hourly space velocity is 0.1-800h<-1>, the reaction pressure is 0.10-1.0MPa, the weight ratio of the catalytic cracking catalyst to the raw materials is 1-150 and the weight ratio of water vapor to the raw materials is 0.05-1.0, the spent catalyst and reaction oil and gas are separated, the spent catalyst returns to the reactor after the regeneration, the separated reaction oil and gas are separated to obtain target products of low-carbon olefins, aromatic hydrocarbons and the raw materials for re-cracking, wherein the raw materials for re-cracking are re-cracked after hydrotreating. The method can product the propylene and other low-carbon olefins from the heavy raw materials to the maximum extent, wherein the yield of the propylene is more than 40 percent by weight; meanwhile, the method can co-produce toluene, xylene and other aromatic hydrocarbons, and the yield of the dry gas is unexpectedly reduced by more than 80 percent by weight.

Description

technical field [0001] The invention belongs to a method for catalytic conversion of hydrocarbon oil, more specifically, a method for converting heavy raw materials into low-carbon olefins and aromatics rich in propylene by combining the catalytic cracking and hydrotreating processes of hydrocarbon oil. 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 produc...

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Problems solved by technology

[0012] The above-mentioned prior art still has deficiencies in the design of the molecular cracking reaction of alkanes in the feedstock oil, and the cracking reaction of other hydrocarbon molecules in the feedstock is excessive, resulting in a substantial increase in the yield of dry gas and coke. At the same time, the product distribution of the prior art It is cut according to the conventional FCC fractionation system, 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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