Understanding the Early Stages of the Methanol-to-Olefin Conversion on H-SAPO-34
Understanding the Early Stages of the Methanol-to-Olefin Conversion on H-SAPO-34
复制标题
了解 H-SAPO-34 上甲醇转化为烯烃的早期阶段
DOI：
10.1021/cs5015749
复制
发表时间：
2015-01-01
期刊：
影响因子：
12.9
通讯作者：
Hunger, Michael
中科院分区：
文献类型：
--
作者：
Dai, Weili;Wang, Chuanming;Hunger, Michael
在H-SAPO-34上甲醇制烯烃（MTO）转化的早期阶段，在以高活性聚甲基苯阳离子作为最重要的中间体达到稳定状态之前，人们对其知之甚少。在这项工作中，通过H-1 MAS NMR和C-13 MAS NMR澄清了H-SAPO-34模型催化剂上MTO转化早期阶段碳离子的形成和演化。几个初始物种（即三环化合物、二烯、聚甲基环戊烯基和聚甲基环己烯基阳离子）首次在MTO转化过程中得到直接验证。它们详细的进化网络是通过理论计算建立起来的。基于这些结果，提出了在H-SAPO-34上MTO反应的早期阶段，一个基于烯烃的催化循环是主要的反应途径。在此之后，一个基于芳烃的循环可能会参与长时间的MTO转化。
Little is known on the early stages of the methanol-to-olefin (MTO) conversion over H-SAPO-34, before the steady-state with highly active polymethylbenzenium cations as most important intermediates is reached. In this work, the formation and evolution of carbenium ions during the early stages of the MTO conversion on a H-SAPO-34 model catalyst were clarified via H-1 MAS NMR and C-13 MAS NMR. Several initial species (i.e., three-ring compounds, dienes, polymethylcyclopentenyl, and polymethylcyclohexenyl cations) were, for the first time, directly verified during the MTO conversion. Their detailed evolution network was established from theoretical calculations. On the basis of these results, an olefm-based catalytic cycle is proposed to be the primary reaction pathway during the early stages of the MTO reaction over H-SAPO-34. After that, an aromatic-based cycle may be involved in the MTO conversion for long times on stream.