A bifunctional catalyst, composed of a hydrogenation active metal and an oxophilic promoter for C_Ar–O bond weakening, is effective in the deoxygenation of lignin derivatives due to a contact synergy. A systematic comparison of the physicochemical properties of Ni-based catalysts promoted by metal oxides (i.e., FeO_x, MoO_x, and WO_x) with different extents of oxophilicity was conducted, and their catalytic behaviors were evaluated in the conversion of p-cresol. Ni promoted by WO_x displays the highest oxophilicity among all promoters and is intrinsically more active than NiMo and NiFe in direct deoxygenation (DDO); this characteristic is possibly related to its great hydride mobility. However, in a H₂-pressured system, Ni promoted by MoO_x, which has moderate oxophilicity compared with the employed promoters, generated more DDO product (toluene) than NiFe and NiW. This study discovered that this discrepancy, between the result of the chemical test under normal pressure and the result of the reaction test in an authentic pressurized system concerning the relation between toluene yield and a promoter’s oxophilicity, is related to different hydrogenation rates of toluene. Toluene derived from DDO of p-cresol can be subsequently hydrogenated and thus be turned into methylcyclohexane more rapidly by the NiW catalyst than by NiMo and NiFe catalysts. Hence, both the oxophilicity of a promoter and the inertness of hydrogenation of toluene should be considered in designing a bimetallic catalyst in the conversion of lignin derivatives.

中文翻译：

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强亲氧促进剂会增强直接脱氧作用吗？Ni-Fe ，NiMo和NiW催化剂在对甲酚转化中的研究

一种双功能催化剂，由氢化活性金属和用于C _Ar -O键减弱的亲氧助催化剂组成，由于接触协同作用，可有效地对木质素衍生物进行脱氧。对金属氧化物（FeO _x，MoO _x和WO _x）在不同程度的亲氧性下促进的镍基催化剂的理化性质进行了系统的比较，并评估了它们在对甲酚转化中的催化行为。。Ni由WO _x提升在所有启动子中显示出最高的亲氧性，并且在直接脱氧（DDO）中本质上比NiMo和NiFe更具活性；此特性可能与其强大的氢化物迁移率有关。但是，在H ₂加压系统中，与所用促进剂相比，具有适度的亲氧性的由MoO _x促进的Ni产生的Ni-Fe比NiFe和NiW多。这项研究发现，在常压下的化学测试结果与真实的加压系统中的反应测试结果之间的差异，涉及甲苯收率和助催化剂的亲氧性之间的关系，这与甲苯的不同氢化速率有关。甲苯从DDO衍生p随后，与NiMo和NiFe催化剂相比，NiW催化剂可将-甲酚氢化，从而更快地转变为甲基环己烷。因此，在设计木质素衍生物的转化中的双金属催化剂时，应同时考虑促进剂的亲氧性和甲苯氢化的惰性。