The Effect Of Impurity For The Production Of Ethyl-benzene By Alkylation Of Benzene With Dilute-ethylene

The production of ethyl-benzene from the alkylation of benzene with ethylene is a typical chemical process. In the industrial production process, due to differences of raw materials and reaction conditions, it gradually formed two production processes: pure-ethylene method and dilute-ethylene method.Pure ethylene and benzene were used as raw material for the production of ethyl-benzene in the pure ethylene method. Pure ethylene was mainly prepared by the separation, purification and other technology of the production of naphtha cracking and the investment and cost were high. The dilute-ethylene method attracted widespread attention due to the dilute ethylene in off gas of FCC (dry gas) can be used as raw material. There are many kinds of impurities in the raw materials of dilute-ethylene technology of ethyl-benzene. These impurities have great impact on the catalytic performance and product quality. Therefore, based on SEB-08, the catalyst for alkylation of benzene with dilute ethylene, developed by Shanghai Research Institute of Petrochemical Technology, the micro-device (60g/h) simulation method combined with the actual situation was used to study the effect of the impurities in the raw materials, such as toluene, non-aromatics, water, hydrogen sulfide and alkaline substances, on the alkylation of dilute-ethylene technology for the production of ethyl-benzene.The theoretical analysis and experimental results showed that:1.The toluene increased the content of xylene in the products of alkylation and affected the quality of ethyl-benzene products.2.The propylene and butylene had little effect on the content of xylene in the alkylation products, but the content of propylbenzene and butylbenzene rose significantly.3.The non-aromatic hydrocarbons such as n-hexane, cyclohexane, n-pentane and1-pentene, increased the content of xylene and heavy aromaticsAWater had certain influence on the conversion rate of catalyst.When the content of the water was over1000ppm(parts per million),the ethylene conversion dropped obviously and loss of catalytic activity could be greatly accelerated.5.The alkaline substances, represented by ethanolamine, affected alkylation process the most obviously, because the active centers of alkylation catalysts are acidic, the deactivation of catalyst by alkaline substances is irreversible.6.The content of hydrogen sulfide had little effect on catalyst performance and the quality of ethyl-benzene products, but corrosion degree of equipment and the pipeline increased.7.CH4,C2H6,H2,CO and CO2have no effect on the alkylation, but CO2will cause the pipeline and equipments corrosion. It can help us to correctly determine the cause of the alkylation product composition change by studying the effects of impurities to the alkylation reaction. Then, we can optimize the operating conditions that controlling the content of the impurities in raw materials to reduce the effect of impurities to the alkylation reaction, improve product quality of ethylbenzene and reduce material consumption of fit.