COUPLING CONVERSION OF METHANOL AND BUTYLENE TO PROPYLENE ON Ce-MODIFIED HZSM-5 ZEOLITE CATALYST
In order to further improve the catalytic performance of HZSM-5 zeolite in the coupling conversion of methanol and butylene to propylene,a series of Ce-modified HZSM-5(xCe/HZSM-5)catalysts with different Ce-loading were prepared by impregnation method.The effects of Ce-loading and reaction conditions(methanol/butylene molar ratio,reaction temperature and space time)on the catalytic performance of catalysts were systematically investigated.Combined with the catalyst characterization results,the effects of Ce modification on the performance and physicochemical properties of catalysts were analyzed,and the structure-activity relationship of xCe/HZSM-5 catalyst was discussed.The results showed that under the optimum reaction conditions including a temperature of 550℃,a pressure of 0.1 MPa,a molar ratio of methanol/butylene of 0.8 and a space time of 2.3(gca,·h)/molCH2,2.5Ce/HZSM-5 catalyst with 2.5％Ce loading(w)showed the highest propylene yield of 41.9％.The interaction between Ce and hydroxyl groups(OH)on the HZSM-5 zeolite decreased the Brønsted(B)acid amount and formed a new Lewis(L)acid site Ce(OH)2+,which caused the reduction of the ratio of B/L acid sites,thus,the selectivity and yield of propylene were improved.
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