Selective Intensification for Alkylation Reactions of Benzene and Methanol
Based on the reaction kinetics of the benzene alkylation with methanol,a steady state model of fixed-bed was established.After the verification of the model,the competitiveness of benzene alkylation,toluene alkylation and methanol conversion to olefins was analyzed,and the effects of space speed(WHSV),feed temperature(Tinlet)and feed ratio of benzene to methanol(n)on the reaction process were further investigated.The reaction kinetics analysis showed that the increase of the reaction temperature would increase the reaction rate and facilitate the formation of xylene.However,it was necessary to reduce the concentration of methanol to reduce the reaction rate of methanol conversion to olefin,that was,to improve the alkylation efficiency of methanol.The fixed-bed reactor simulation showed that the output PX selectivity at high WHSV could exceed the industry-grade PX mass fraction of 99%.The increase of Tinlet was beneficial to the improvement of benzene conversion and methanol effective utilization rate,but it would decrease the PX selectivity.The increase of n could improve the alkylation efficiency of methanol,but greatly reduce the benzene conversion and PX selectivity.When the WHSV=32 h-1,n= 4 and the Tinlet=500℃,the benzene conversion rate at the reactor outlet was 12.95%,the utilization rate of methanol alkylation was 55.43%,and the PX selectivity was 99.53%.The results of this study have a certain guiding value for reactor design and further process optimization of benzene alkylation process.
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