Alkali metal oxides supported on SBA-15, M/SBA-15 (M = Li, Na, K, Rb, and Cs), prepared by the impregnation method were characterized and tested for the aldol condensation of methyl acetate and formaldehyde to methyl acrylate (MA). M/SBA-15 catalysts are active for the formation of MA while the support is inert. The supported alkali metals react with hydroxyl groups on SBA-15 by replacing the H atoms and generate weak and medium basic sites. The latter plays an important role in promoting the reaction. Coke formation results in deactivation of Cs/SBA-15, and the deactivated catalyst can be regenerated by burning off the coke. Two possible reaction pathways for the formation of MA were explored using quantum calculations. The predicated activity for M/SBA-15 is consistent with the experimental observations. A pathway with adsorbed enol molecule as an intermediate was suggested to be predominant for the formation of MA.

中文翻译：

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SBA-15负载的碱金属氧化物上乙酸甲酯和甲醛在气相中羟醛缩合的实验和理论研究

表征了通过浸渍法制备的负载在SBA-15，M / SBA-15（M = Li，Na，K，Rb和Cs）上的碱金属氧化物，并测试了乙酸甲酯和甲醛在醛醇缩合反应中生成丙烯酸甲酯的能力。 （嘛）。当载体为惰性时，M / SBA-15催化剂对MA的形成具有活性。负载的碱金属通过取代H原子与SBA-15上的羟基反应，并生成弱和中等的碱性位点。后者在促进反应中起重要作用。焦炭的形成导致Cs / SBA-15失活，并且可以通过烧掉焦炭来再生失活的催化剂。使用量子计算探索了两种可能的MA形成反应途径。M / SBA-15的预测活性与实验观察结果一致。