Wen Wu, Xiao Tianci, Feng Beibei, Zhou Chaoqun, Li Jian, Ma Hao, Zhou Zhongyue, Zhang Ying, Yang Jiuzhong, Wang Zhandong, Qi Fei, Bao Jun, Liu Chengyuan, Pan Yang
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, Anhui, P. R. China.
Key Laboratory for Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China.
Commun Chem. 2022 Nov 19;5(1):153. doi: 10.1038/s42004-022-00771-8.
Gallium-modified HZSM-5 zeolites are known to increase aromatic selectivity in methanol conversion. However, there are still disputes about the exact active sites and the aromatic formation mechanisms over Ga-modified zeolites. In this work, in situ synchrotron radiation photoionization mass spectrometry (SR-PIMS) experiments were carried out to study the behaviors of intermediates and products during methanol conversion over Ga-modified HZSM-5. The increased formaldehyde (HCHO) yield over Ga-modified HZSM-5 was found to play a key role in the increase in aromatic yields. More HCHO was deemed to be generated from the direct dehydrogenation of methanol, and GaO in Ga-modified HZSM-5 was found to be the active phase. The larger increase in aromatic production over Ga-modified HZSM-5 after reduction‒oxidation treatment was found to be the result of redispersed GaO with smaller size generating a larger amount of HCHO. This study provides some new insights into the internal driving force for promoting the production of aromatics over Ga-modified HZSM-5.
众所周知，镓改性的HZSM-5沸石可提高甲醇转化中的芳烃选择性。然而，关于镓改性沸石的确切活性位点和芳烃形成机制仍存在争议。在这项工作中，进行了原位同步辐射光电离质谱（SR-PIMS）实验，以研究甲醇在镓改性HZSM-5上转化过程中中间体和产物的行为。发现镓改性HZSM-5上甲醛（HCHO）产率的增加在芳烃产率的提高中起关键作用。更多的HCHO被认为是由甲醇直接脱氢产生的，并且发现镓改性HZSM-5中的GaO是活性相。还原-氧化处理后，镓改性HZSM-5上芳烃产量的更大增加被发现是尺寸更小的再分散GaO产生大量HCHO的结果。该研究为促进镓改性HZSM-5上芳烃生成的内在驱动力提供了一些新见解。
