The Study Of Catalysts In The Alkylation Of Benzene With Methanol

In this paper,the alkylation of benzene with methanol was studied with HZSM-5 molecular sieve as catalyst.The influence of Si/Al ratio and commercial sources on the alkylation performance of benzene with methanol were investigated.HZSM-5 molecular sieve with Si/Al ratio was further modified.It was inspected that the effect of modification on the physical and chemical properties of the catalyst and the alkylation performance of benzene with methanol.The alkylation performance of benzene with methanol on HZSM-5 zeolite with different Si/Al ratio was firstly investigated.The results showed that with the increase of Si/Al ratio,the alkylation activity of catalysts increased at the beginning and then decreased.HZSM-5 with Si/Al ratio in the range of 196~219 worked stably within 10 h with 54% of benzene conversion had been achieved,because of few strong acid sites and more mesoporous channels.Therefore,the optimum Si/Al ratio range of HZSM-5 was 196~219.It was further examined that the influence of commercial HZSM-5 sources in the range of optimum Si/Al ratio on the alkylation performance of benzene with methanol.HZSM-5 from different sources had similar alkylation performance and different pore structure,which indicated that the key factor affected alkylation performance of benzene with methanol was Si/Al ratio.HM provide by Huangma chemical industry was taken as main catalyst,whose active component was ZSM-5 zeolite.The experiment that HM was modified by XO with incipient-wetness impregnation method had been conducted,which studied the effect of XO loading on the alkylation performance of benzene with methanol.It had beed found that XO was mainly distributed in the mesoporous channels of HM.Strong acid sites gradually decreased and eventually were overwritten with the increase of XO loading.The ability activating methanol of YO modified catalysts decreased,while the methanol adsorbing capacity increased.With the increase of XO loading,the alkylation activity slightly reduced then sharply decreased,and the amount of carbon content decreased gradually.The optimum XO loading was 2.5%.This experiment further modified the XO/HM catalyst with YO.The strong acid sites of the modified catalyst were partly recovered.The ability to activate and adsorb methanol were both enhanced.The influence of carrier gas on the alkylation performance of XO/HM catalysts modified by different YO loading had been taken into account.The catalytic activity gradually decreased with the increase of YO loading under N2 atmosphere.The alkylation performance of benzene with methanol of low YO loading modified catalysts had little difference within 10 h,with 52% of benzene conversion was achieved.The alkylation activity sharply decreased when the YO loading increased to nYO/nXO=2/7.The stability of HM,XO/HM and YO-XO/HM catalysts were evaluated by operating 20 h under the same reaction conditions.Compared with the unmodified HM,XO/HM catalyst had better stability and lower deactivation rate.The stability of YO-XO/HM catalysts had greatly improved,and the optimum YO loading range was nYO=1/30~1/7n XO.