Coking kinetics on the catalyst during alkylation of fcc off-gas with benzene to ethylbenzene Original Research Article

The production of ethylbenzene from the alkylation of dilute ethylene in fcc off-gases with benzene has been commercialized in China over a newly developed catalyst composed of ZSM-5/ZSM-11 co-crystallized zeolite. The duration of an operation cycle of the commercial catalyst could be as long as 180 days. The conversion of ethylene could attain higher than 95%, while the amount of coke deposited on the catalyst was only about 10 wt.%. Thermogravimetry (TG) was used to study the coking behavior of the catalyst during the alkylation of fcc off-gas with benzene to ethylbenzene. Based on effects of reaction time, reaction temperature, reactants and products on coking during the alkylation process, it is found that the coking rate during the alkylation procedure follows the order: ethylbenzene>ethylene>propylene>benzene for single component, and benzene–ethylene>benzene–propylene for bi-components under the same reaction condition. Furthermore, the coking kinetic equations for benzene–ethylene, benzene–propylene and ethylbenzene were established.