Mechanism Studies of the Conversion of13C-Labeledn-Butane on Zeolite H-ZSM-5 by Using13C Magic Angle Spinning NMR Spectroscopy and GC–MS Analysis
作者:Mikhail V. Luzgin、Alexander G. Stepanov、Sergei S. Arzumanov、Vladimir A. Rogov、Valentin N. Parmon、Wei Wang、Michael Hunger、Dieter Freude
DOI:10.1002/chem.200500382
日期:2006.1
both isobutane and propane are formed through intermolecular pathways. According to 13C MAS NMR kinetic measurements, both pathways proceed with nearly the same activation energies (E(a) = 75 kJ mol(-1) for the scrambling and 71 kJ mol(-1) for isobutane and propane formation). This can be rationalized by considering the intermolecular hydride transfer between a primarily initiated carbenium ion and
通过使用13C MAS NMR光谱法(MAS =魔角旋转),已证明在430-470 K的沸石H-ZSM-5上选择性13C标记的正丁烷的转化过程通过两个途径进行:1)加扰在正丁烷分子中具有选择性的13C标记,以及2)低聚裂化和混合聚合。后一种方法(2)与烷基取代的环戊烯基阳离子和稠合的芳族化合物同时生产异丁烷和丙烷。原位13 C MAS NMR和互补的原位GC-MS数据提供了13 C-标记加扰的单分子机理的证据,而异丁烷和丙烷均通过分子间途径形成。根据13C MAS NMR动力学测量,两种途径都以几乎相同的活化能进行(加扰的E(a)= 75 kJ mol(-1)和异丁烷和丙烷的形成为71 kJ mol(-1))。可以通过考虑将最初引发的碳正离子与正丁烷之间的分子间氢化物转移作为沸石H-ZSM-5上正丁烷转化率的决定速率阶段来使其合理化。