Method for preparing ethylene and propylene by taking naphtha as raw material

Abstract

The invention belongs to the technical field for producing ethylene and propylene, and particularly relates to a method for preparing ethylene and propylene by taking naphtha as the raw material. The method for preparing ethylene and propylene by taking naphtha as the raw material comprises the following steps: (1) preparation of a composite catalyst; (2) catalyzed cracking; and (3) separation of products. The method for preparing ethylene and propylene by taking naphtha as the raw material has simple steps and reasonable design, and helps to substantially improve conversion rate of naphtha and yields of ethylene and propylene.

Description

technical field [0001] The invention belongs to the technical field of producing ethylene propylene, and in particular relates to a method for producing ethylene propylene with naphtha as a raw material. Background technique [0002] Ethylene, propylene and other low-carbon olefins, as important basic raw materials of petrochemical industry, play a pivotal role in the petrochemical industry. Among many hydrocarbon cracking ethylene production technologies, tube furnace pyrolysis plays a dominant role in ethylene production. However, with the increasing demand for propylene derivatives, the co-production of propylene through thermal cracking can no longer meet the growing demand for propylene in the domestic and foreign markets. In addition, steam pyrolysis technology also has problems such as high energy consumption and equipment investment, narrow range of cracking raw material selection, and serious environmental pollution. Steam cracking reaction temperature is high, en...

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Problems solved by technology

When this design is applied to high-temperature catalytic cracking, the reaction temperature of the reactant gas in the feed pipe extending into the reactor part is already the same as the reaction temperature of the reactor. At this time, high-temperature thermal cracking will occur in the feed pipe with the generation of coke And the inevitable slight fluctuation of the internal pressure of the reactor caused by the operation makes it easy for the catalyst to enter the reaction feed pipe. These reasons can easily lead to the blockage of the reactant feed pipe during the reaction process and the reaction cannot be carried out normally.

Usually after 2 hours of reaction, due to the increase of coking, the reaction pressure begins to increase and the operating conditions begin to deteriorate

Therefore, when using a traditional fixed fluidized bed device for reaction, the control requirements for operating conditions such as temperature, pressure, and feed time are relatively strict, and strict feed ratio, temperature, and pressure control are required, otherwise the reaction feed pipe Easy to block, the reaction cannot proceed normally

The semicircular design at the bottom of the reactor makes the reactor structure simple and easy to process, but the fluidization effect of the catalyst is determined by the arc of the semicircle and the flow rate of the feed gas, which cannot be adjusted flexibly, which limits the capacity of the reactor. The type of reaction applied, the range of raw materials and process conditions, and the state of the gas flow at the bottom of the reactor is complex, which is prone to channeling and other phenomena that affect the fluidization of the catalyst and affect the catalytic performance

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