The co-aromatization of methane and organic compounds using metal-modified zeolite catalysts represents a promising approach for the direct conversion of natural gas into valuable aromatics. In this work, we employ solid-state nuclear magnetic resonance (NMR) spectroscopy to systematically examine the reaction mechanism and evaluate the impact of co-feeding furan on methane aromatization over Mo/ZSM-5 zeolite. The results reveal a dual role of furan in promoting methane to aromatics and stabilizing the Mo/ZSM-5 zeolite catalyst in the co-aromatization. It is found that co-feeding a moderate amount of furan enhances methane conversion and boosts the selectivity to benzene, toluene, and xylene (BTX). The ¹²C/¹³C isotope switching experiments coupled with ¹H and ¹³C MAS NMR spectroscopy reveal that furan actively participates in the methane aromatization reaction by forming an olefin pool, which promotes methane activation and contributes to the following aromatics formation. Two-dimensional ¹H–⁹⁵Mo heteronuclear correlation NMR spectroscopy indicates that furan facilitates the activation of Mo oxides into MoO_xC_y species, which serve as the active sites for methane aromatization. The co-feeding furan also helps to enhance catalyst stability by limiting the agglomeration of Mo and the deposition of coking species.

中文翻译：

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钼/ZSM-5 催化甲烷与呋喃共芳构化：用固态核磁共振揭示机理

使用金属改性沸石催化剂对甲烷和有机化合物进行共芳构化是将天然气直接转化为有价值的芳烃的一种有前景的方法。在这项工作中，我们采用固态核磁共振（NMR）光谱系统地研究了反应机理并评估了共进料呋喃对Mo/ZSM-5沸石上甲烷芳构化的影响。结果揭示了呋喃在促进甲烷生成芳烃和稳定共芳构化中Mo/ZSM-5沸石催化剂方面的双重作用。研究发现，共进料适量的呋喃可提高甲烷转化率并提高苯、甲苯和二甲苯 (BTX) 的选择性。¹² C/ ¹³ C同位素转换实验结合¹ H和¹³ C MAS NMR光谱表明，呋喃通过形成烯烃库积极参与甲烷芳构化反应，从而促进甲烷活化并有助于随后芳烃的形成。二维¹ H- ⁹⁵ Mo 异核相关核磁共振波谱表明，呋喃促进 Mo 氧化物活化成 MoO _x C _y物质，作为甲烷芳构化的活性位点。共进料呋喃还通过限制Mo的团聚和焦化物质的沉积来帮助增强催化剂稳定性。