Ni/α-MoC催化甲醇水蒸汽重整及木质素芳醚键选择氢解耦合反应过程和机理研究

Lignocellulose (lignin, cellulose, hemicellulose) is the most abundant renewable biomass resource available on earth. The efficient utilization of renewable lignin for the synthesis of oxygen-containing aromatic chemicals is of great significance for the partial substitution of petroleum and establishing novel sustainable chemical and chemical-engineering processes. In this project, we propose to use Ni/α-MoC catalyst to selective converted the lignin to high value-added oxygen-containing aromatic chemicals through highly coupled reaction between steam reforming of methanol and selectively hydrogenolysis of lignin aryl bonds. By fine tuning the synthesis parameters, the surface metallicity and acidity of the catalysts will be tunable. With the aim to control the products selectivity, the cascade reaction over Ni/α-MoC catalyst via hydrogen transfer will be deeply explored through in-situ characterization techniques, isotopic experiments and model reactions. By studying the reaction mechanism and reaction kinetics, the nature of the active sites for consecutive reactions, as well as the cooperation between different sites will be clarified. It is expected that the results obtained under the funding of this project will help to better understand the selective activation and breaking mehcanism of specific C-O bonding in the biomass, and provide a guide for the selective transformation of lignin to valuable oxygen containing aromatic chemicals.

木质纤维素（木质素、纤维素、半纤维素）是自然界中储量最丰富的可再生资源，高效利用木质素合成含氧芳香化学品，对于部分替代化石资源，以及建立可持续发展的化学化工新过程，具有重大意义。本项目以Ni/α-MoC为催化剂，通过甲醇/水重整制氢与选择切断木质素芳醚键的高度耦合定向转化获取含氧芳香化学品。拟通过对催化剂制备参数的精细调控，获得催化剂表面金属性和酸性的高度可控；采用多种原位表征技术、同位素实验、模型反应等手段，重点研究Ni/α-MoC催化串联反应高效耦合的催化机理和氢转移的独特机制，实现产物选择调控；通过对反应机制和反应动力学研究，阐明各个串联反应的催化活性本质以及相互协同作用的关系，深入理解生物质分子中特定C-O键的选择活化和断键机理，为木质素高选择转化为含氧芳香化学品提供理论依据。

木质素是自然界中储量最丰富的可再生资源，高效利用木质 素合成芳香化学品，对于部分替代化石资源，以及建立可持续发展的化学化工新过程，具有重大意义。本项目以Ni/a-MoC和Ni/W2C/AC为催化剂在釜式反应器和固定床反应器中分别研究了耦合脱氢和加氢脱氧或氢解过程。在Ni/a-MoC催化剂中，通过考察反应温度，甲醇和水的摩尔比，分析甲醇转化率，产氢速率，反应产物（CO）选择性，转化频率等发现，4%Ni/α-MoC表现出最高的转化频率，在甲醇和水体积比为1比1，260℃的条件下，获得21.8 mmolH2/g/h，一氧化碳的选择性小于1%，转化频率高达1582；在220-260℃的条件下，木质素模型底物苯氧基苯乙醇和苯氧基苯乙酮均完全转化。对于Ni-W2C/AC催化剂体系，研究其催化耦合柠檬烯脱氢和生物油脱氧的反应过程，通过改变进料比例，研究了脱氢-加氢脱氧过程中脱氢及原位产氢机制。此外，本项目还发展了一种表面修饰催化剂的制备方法，通过多巴胺的自聚合作用，在钯基催化剂表面形成1-3层氮掺杂碳修饰层，探清了氮掺杂碳层修饰钯基催化剂结构对碳-碳偶联反应和香兰素选择加氢和苯乙炔选择加氢的作用机理，为高效设计非均相催化剂提供基础科学信息。同时为木质素高值化利用提供理论依据。