A series of single-phase mixed metal carbides of molybdenum and tungsten (Mo_2-xW_xC, 0 < x < 2) was synthesized. Precursors with intimately mixed metals were prepared by flash-freezing aqueous solutions of molybdenum and tungsten salts in liquid nitrogen and subsequent freeze-drying. The powders of freeze-dried samples had small particles that facilitated reduction and carburization. Direct carburization of freeze-dried precursors at a final temperature of 650 °C resulted in formation of single-phase metal carbides with hexagonal structures and CO adsorption capacities of 15–27 μmol/g. All carbides were catalytically active for conversion of toluene at a total pressure of 21 bar, and a H₂:toluene molar ratio of 33. At a reaction temperature of 250 °C, only methylcyclohexane formed at TOFs of 0.13 (Mo_0.5W_1.5C) ― 2.1 s⁻¹ (Mo₂C). Activation energies for ring hydrogenation were in the range of 40–60 kJ/mol. At 400 °C, catalysts deactivated for 24 h before stabilizing. At steady state, methylcyclohexane and small alkanes formed via ring hydrogenation and hydrogenolysis, indicating the presence of sites with metallic character. Disproportionation of toluene to benzene and xylenes indicated the presence of weakly acidic sites. An excess of benzene was attributed to the presence of carbon vacancies on the surface, which formed more readily in the tungsten-containing carbides.

合成了一系列钼和钨的单相混合金属碳化物（Mo _2-x W _x C，0 <x <2）。通过将钼和钨盐的水溶液在液氮中速冻，然后进行冷冻干燥，可以制备出具有紧密混合的金属的前体。冷冻干燥样品的粉末具有促进还原和渗碳的小颗粒。最终温度为650°C的冷冻干燥前体直接渗碳导致形成具有六方结构和CO吸附容量为15–27μmol/ g的单相金属碳化物。所有碳化物均具有催化活性，可在21 bar和H ₂的总压力下转化甲苯：甲苯的摩尔比为33。在250℃的反应温度下，仅在TOF为0.13（Mo _0.5 W _1.5 C）〜2.1s ^-1（Mo ₂ C）时形成甲基环己烷。环氢化的活化能在40–60 kJ / mol的范围内。在400°C下，催化剂在稳定之前会失活24小时。在稳态下，通过环氢化和氢解反应形成甲基环己烷和小烷烃，表明存在具有金属特征的位点。甲苯歧化为苯和二甲苯表明存在弱酸性位点。苯的过量归因于表面上存在碳空位，碳空位更容易在含钨的碳化物中形成。