Baba Toshihide, Abe Yoshimune, Nomoto Kenji, Inazu Koji, Echizen Tsuneo, Ishikawa Akio, Murai Kazuhito
Department of Environmental Chemistry and Engineering, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259-G1-14 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan.
J Phys Chem B. 2005 Mar 10;109(9):4263-8. doi: 10.1021/jp045640t.
Methane is shown to react with ethene over In-loaded ZSM-5 to higher hydrocarbons such as propene and toluene at around 673 K. Such methane conversion is not catalyzed by proton-exchanged ZSM-5 (H-ZSM-5) under the same conditions, only C2H4 being converted to higher hydrocarbons. By using 13C-labeled methane (13CH4) as a reactant, the reaction paths for the formation of propene, benzene and toluene were examined. 13C-labeled propene (13CC2H6) is formed by the reaction of 13CH4 with C2H4. The lack of 13C-labeled benzene revealed that propene is not transformed to benzene, which instead originates entirely from C2H4. The 13C atom is inserted both into the methyl group and benzene ring in the toluene formed. This indicates that toluene is formed by two reaction paths; the reaction of 13CC2H6 with butenes formed by the dimerization of C2H4 and the reaction of benzene with 13CH4. The existence of the latter path was proved by the direct reaction of 13CH4 with benzene. The reaction of methane with benzene was also carried out in a continuous flow system over In-loaded ZSM-5. The reaction afforded 7.6% and 0.9% yields of toluene and xylenes, respectively, at 623 K.
研究表明，在负载铟的ZSM-5催化剂上，甲烷与乙烯在约673 K的温度下反应生成丙烯和甲苯等高碳氢化合物。在相同条件下，质子交换的ZSM-5（H-ZSM-5）不能催化这种甲烷转化反应，在此条件下H-ZSM-5仅能将乙烯转化为高碳氢化合物。以13C标记的甲烷（13CH4）作为反应物，研究了丙烯、苯和甲苯的形成反应路径。13CH4与乙烯反应生成了13C标记的丙烯（13CC2H6）。未检测到13C标记的苯，这表明丙烯不会转化为苯，苯完全由乙烯生成。在生成的甲苯中，13C原子既插入到甲基中，也插入到苯环中。这表明甲苯通过两条反应路径生成：13CC2H6与乙烯二聚生成的丁烯反应，以及苯与13CH4反应。13CH4与苯的直接反应证明了后一条反应路径的存在。甲烷与苯的反应也在负载铟的ZSM-5催化剂的连续流动体系中进行。在623 K时，该反应的甲苯产率为7.6%，二甲苯产率为0.9%。
