甲烷直接催化氧化制甲醇催化剂及反应机理

研究甲烷合成甲醇的催化剂及催化机理是甲烷直接催化氧化制甲醇的关键。本文综述了甲烷合成甲醇的Pt系催化剂、Pd系催化剂、Rh系催化剂、Fe改性沸石催化剂、Cu改性沸石催化剂、改性金属有机框架材料催化剂以及相应的催化机理。结果表明，Pt系催化剂中K₂PtCl₄、Pt(bpym)Cl₂、Pt(bipy)Cl₂催化甲烷制甲醇机理为亲电取代反应。Pd系催化剂中Pd(OAc)₂在CF₃COOH水溶液中通过多步电子传递链将甲烷转化为甲醇；Pd/C在乙酸水溶液中催化甲烷合成甲醇是亲电取代和活性氧物种氧化两种机理共同作用的结果。Rh系催化剂中的Rh/ZSM-5、Rh/TiO₂通过锚定在载体孔道内的一价Rh与CO、H₂O和O₂作用将甲烷转化为甲醇。Fe、Cu改性沸石催化剂及改性金属有机框架材料催化剂通过均裂、异裂等自由基反应转化甲烷得到甲醇。指出研究高效活化甲烷分子和抑制甲醇深度氧化催化剂的设计、制备及深入探究其催化机理仍然是今后的研究重点。

Catalyst and reaction mechanism for direct catalytic oxidation of methane to methanol

The catalysts and the catalytic mechanisms are the keys to the direct catalytic oxidation of methane to methanol. In this paper, platinum catalyst, palladium catalyst, rhodium catalyst, Fe-modified zeolite catalyst, Cu-modified zeolite catalyst and modified metal-organic framework catalyst for methane to methanol as well as the corresponding catalytic mechanism were reviewed. The results showed that methane to methanol catalyzed by platinum catalysts of K₂PtCl₄, Pt(bpym)Cl₂ and Pt(bipy)Cl₂ is electrophilic substitution reaction, while that by Pd(OAc)₂ of palladium catalyst system in aqueous solution of CF₃COOH is through multi-step electron transport chain and that by Pd/C in acetic acid aqueous solution is the result of the interaction of electrophilic substitution and oxidation of reactive oxygen species. Through the interaction of monovalent Rh anchored in the carrier channel with CO, H₂O and O₂, Rh/ZSM-5 and Rh/TiO₂ in rhodium catalyst system converts methane into methanol. Regarding the Fe-modified zeolite catalyst, Cu-modified zeolite catalyst and modified metal-organic framework material catalyst, free radical reactions such as homolysis and heterolysis works. Design and preparation of catalysts for highly activating methane molecule and inhibiting deep oxidation of methanol and in-depth study of its catalytic mechanism are still the focus of future research.