Method for reducing alkylation reaction by-product propylbenzene

Abstract

The invention relates to a method for reducing alkylation reaction by-product propylbenzene. According to the method, two alkylation reactors are changed to operate in series. The method comprises following steps: injecting gas-phase pure ethylene into dry gas through a technical improvement line of liquid phase method to increase the volume fraction of ethylene in the dry gas to be about 18-24% (V), reduce the volume fraction of propylene to be less than about 1% (V), meanwhile, increase the circulating benzene amount of a device for preparing ethylbenzene by dry gas method; carrying out heattaking adjustment on a circulating benzene heating furnace and a steam generator to maintain inlet temperature of the two gas-phase alkylation reactors to be 320 + / -15 DEG C; carrying out component analysis on inlet dry gas, inlet circulating benzene, outlet alkylation liquid of the gas-phase alkylation reactors, and top outlet alkylation tail gas of an adsorption tower, calculating the conversion rate of ethylene and the selectivity on ethylbenzene, meanwhile, and comparing the unit generation amount of propylbenzene at the same time. According to the method, the content of ethylene in dry gas is increased and the content of propylene is reduced through injection of gas phase pure ethylene, so that the generation amount of propylbenzene is reduced, and the steps play a decisive role in reducing alkylation reaction byproducts.

Description

technical field [0001] The invention relates to the field of petrochemical production, in particular to a method for reducing the by-product propylbenzene of an alkylation reaction. Background technique [0002] At present, the gas-phase dry gas production of ethylbenzene technology developed in China has relatively low requirements on the purity of the raw material dilute ethylene. The volume fraction of dilute ethylene in most dry gases is about 12%-20%, and the raw material dilute ethylene can be directly entered without pressurization. The reaction pressure of the reactor is relatively low. Although the content of propylene in the dry gas is reduced as much as possible through absorption, it is still greatly affected by the content of olefins such as propylene in the raw material dry gas after catalytic cracking. Propylene will combine with benzene to form propylbenzene, which will increase the amount of toluene produced, resulting in more by-products, lower conversion r...

AI Technical Summary

Problems solved by technology

[0002] At present, the gas-phase dry gas Ethylbenzene production technology developed in China has relatively low requirements on the purity of the raw material dilute ethylene. The volume fraction of dilute ethylene in most dry gases is about 12%-20%, and the raw material dilute ethylene can be directly entered without pressurization. Reactor, the reaction pressure is low, although the content of propylene in the dry gas is reduced as much as possible through absorption, but it is still greatly affected by the content of olefins such as propylene in the raw material dry gas after catalytic cracking

Propylene will combine with benzene to produce propylbenzene, which will increase the amount of toluene produced, resulting in more by-products, lower conversion rate of ethylene and lower yield of ethylbenzene, resulting in increased benzene consumption and increased product cost