Studies On Ethylbenzene Synthesis By Benzene Alkylation With Ethane In The Presence Of HCl And O₂ Over Mn-CeO₂/H-ZSM-5 Catalyst

Ethylbenzene is an important raw chemical,which is mainly used for the production of styrene(important polymer monomer).At present,ethylbenzene is mainly produced by the alkylation of benzene with ethylene.Due to the depletion of oil resources,the use of cheap and rich sources of ethane as raw material to replace ethylene in the production of ethylbenzene has raised much attention.Based on our previous research on oxidative chlorination of ethane to ethylene,a new strategy of the production of ethylbenzene by one step alkylation under benzene and ethane in the presence of HCl and O2 was proposed in this thesis.We developed a bifunctional catalyst,aimed to produce the ethylbenzene by coupling the oxidative chlorination of ethane to ethylene and benzene alkylation with ethylene.We first investigated the catalytic reactions of oxidative chlorination of ethane and benzene alkylation with ethylene.The results showed that the CeO2 nanorods with a load of 8 wt%Mn was the most efficient catalyst,which exhibited C2H4 selectivity of 69%and C2H6 conversion of 94%at 450? and atmospheric pressure.In order to achieve a highly selective conversion of ethane to ethylbenzene,the alkylation reaction is carried out under the optimum reaction conditions based on the oxidative chlorination of ethane for the production of ethylene.The benzene alkylation with ethylene catalyzed by H-ZSM-5 zeolite under atmospheric pressure was studied simultaneously.The effects of silica-alumina ratio,reaction temperature,ethylene space velocity and benzene/ethylene molar ratio on the catalytic performances were studied detailed.The results showed that under the reaction conditions of 380 ?,molar ratio of benzene/ethylene of 5:1,the C2H4 conversion of 95%and ethylbenzene selectivity of 78%could be achieved under the H-ZSM-5 zeolite with a silica-alumina ratio of 50.We further prepared the bifunctional catalyst combined the Mn-CeO2 and H-ZSM-5.Aiming to study the intimacy between these two components,we coupled Mn-CeO2 and H-ZSM-5 using the methods of double bed,mechanical mixing and grinding,respectively.The catalytic performance over different coupling methods was investigated.We studied the effects of H-ZSM-5/Mn-CeO2 weight ratio,reaction temperature,space velocity and acidity of zeolite on alkylation reaction of benzene and ethane in the presence of HCl and O2.We found that,with the increase of the contact degree of the two components of the catalyst,the alkylation of benzene with ethylene produced from the chlorine oxidation reaction promotes the conversion of ethane,and thus increased the yield of ethylbenzene under the bifunctional catalyst prepared by grinding method.The conversion of ethane was 64%,and the selectivity of ethylbenzene was 45%when the molar ratio of benzene/ethylene was 3.2 and the reaction temperature was at 430 ?.The results of catalyst characterization show that the H-ZSM-5 zeolite with too strong or too weak acidity is not conducive to the formation of ethylbenzene.In the process of reaction,HCl will cause the drain of framework aluminum,leading to the decrease of ethylbenzene selectivity.