Mo-Zn/HZSM-5催化剂上甲烷与丙烷混合物的无氧芳构化

研究了甲烷和丙烷的混合气体在x%Mo+6%Zn/HZSM-5催化剂上(x=0.3,0.5,0.7,0.9)的无氧芳构化反应性能.结果表明,在873K,GHSV=3L/(g·h)和n(C1)/n(C3)=1.0条件下,甲烷的转化率在29%～35%之间,芳烃选择性大于80%.其中0.7%Mo+6%Zn/HZSM-5对甲烷表现出最优的活性,甲烷转化率达到34.8%,丙烷转化率为69.6%.探讨了反应时间和n(C1)/n(C3)比对甲烷和丙烷转化率及其产物分布的影响.结果显示,丙烷的存在促使甲烷活化并参与芳构化反应.同位素13CH4示踪实验发现,13C进入了C6H6+,C7H8+和C8H10+碎片中,进一步证实了甲烷进入芳烃形成过程.此种用丙烷活化甲烷的过程可能为天然气和炼厂气的直接利用提供了一个新的反应途径.

Non-oxidative Aromatization of Methane by Using Propane as Co-reactant over Mo-Zn/HZSM-5 Catalyst

The non-oxidative conversion of methane(C1) into aromatic hydrocarbons by using propane(C3) as co-reactant over x%Mo+6%Zn/HZSM-5 catalysts was studied. C1 conversion was very high, reaching 29%35%. Selectivity of aromatic products reaches above 80% at 873 K and GHSV=3 L/(g·h) with n(C1)/n(C3)=1.0. The excellent conversion of C1(34.8%) was obtained over 0.7%Mo+6%Zn/HZSM-5 catalyst at 873 K and n(C1)/n(C3)=1.0. The effects of time-on-stream and n(C1)/n(C3) on C1 and C3 conversion and the products distribution were analyzed in order to obtain information about C1 incorporation into the aromatic products and the evolution of different species. C1 incorporation was conclusively confirmed by the mass spectral analyses of aromatic products produced in a run with 13CH4, which shows a significant 13C enrichment in the C6H6+, C7H8+ and C8H10+ fragments. The methane activation could result from its hydrogen-transfer reaction with alkenes. This process was hoped to provide a novel route for the chemical utilization of natural gas and refinery gas.