Kiani Daniyal, Sourav Sagar, Tang Yadan, Baltrusaitis Jonas, Wachs Israel E
Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA 18015, USA.
Chem Soc Rev. 2021 Jan 21;50(2):1251-1268. doi: 10.1039/d0cs01016b. Epub 2020 Dec 7.
This review focuses on recent fundamental insights about methane dehydroaromatization (MDA) to benzene over ZSM-5-supported transition metal oxide-based catalysts (MO/ZSM-5, where M = V, Cr, Mo, W, Re, Fe). Benzene is an important organic intermediate, used for the synthesis of chemicals like ethylbenzene, cumene, cyclohexane, nitrobenzene and alkylbenzene. Current production of benzene is primarily from crude oil processing, but due to the abundant availability of natural gas, there is much recent interest in developing direct processes to convert CH to liquid chemicals. Among the various gas-to-liquid methods, the thermodynamically-limited Methane DehydroAromatization (MDA) to benzene under non-oxidative conditions appears very promising as it circumvents deep oxidation of CH to CO and does not require the use of a co-reactant. The findings from the MDA catalysis literature is critically analyzed with emphasis on in situ and operando spectroscopic characterization to understand the molecular level details regarding the catalytic sites before and during the MDA reaction. Specifically, this review discusses the anchoring sites of the supported MO species on the ZSM-5 support, molecular structures of the initial dispersed surface MO sites, nature of the active sites during MDA, reaction mechanisms, rate-determining step, kinetics and catalyst activity of the MDA reaction. Finally, suggestions are given regarding future experimental investigations to fill the information gaps currently found in the literature.
本综述聚焦于近期关于在ZSM-5负载的过渡金属氧化物基催化剂（MO/ZSM-5，其中M = V、Cr、Mo、W、Re、Fe）上甲烷脱氢芳构化（MDA）制苯的基础见解。苯是一种重要的有机中间体，用于合成乙苯、异丙苯、环己烷、硝基苯和烷基苯等化学品。目前苯的生产主要来自原油加工，但由于天然气资源丰富，近期人们对开发将CH转化为液体化学品的直接工艺兴趣浓厚。在各种气制液方法中，非氧化条件下热力学受限的甲烷脱氢芳构化（MDA）制苯似乎很有前景，因为它避免了CH深度氧化为CO，且无需使用共反应物。本文对MDA催化文献的研究结果进行了批判性分析，重点是原位和操作光谱表征，以了解MDA反应之前和期间催化位点的分子水平细节。具体而言，本综述讨论了负载的MO物种在ZSM-5载体上的锚定位点、初始分散表面MO位点的分子结构、MDA过程中的活性位点性质、反应机理、速率决定步骤、动力学以及MDA反应的催化剂活性。最后，针对未来的实验研究提出了建议，以填补目前文献中存在的信息空白。
