Catalyst characteristics affecting product selectivity and mechanistic aspects of formation of Mo-carbene species in the metathesis of ethylene and trans-2-butene to propylene over MoO_x/AlSiO_x were elucidated by complementary techniques. Steady-state catalytic tests revealed that reaction pathways leading to propene formation depend on the kind (highly dispersed or polymerized) of MoO_x species, from which Mo-carbene species are formed in situ. C₃H₆ is produced directly through metathesis of C₂H₄ and trans-2-C₄H₈ on Mo-carbenes originated from polymerized MoO_x species, whereas the metathesis of 1- and 2-butenes plays an important role for propene formation on Mo-carbenes formed from highly dispersed MoO_x. In situ FTIR spectroscopy and kinetic analysis suggest that the pathways of propene formation and accordingly the selectivity are determined by the ability of C₂H₄ to react with oxidized MoO_x species and Mo-carbenes. This feed component interacts with highly dispersed MoO_x species more weakly than with polymerized ones. Moreover, C₂H₄ adsorbs more strongly on Mo-carbenes formed from highly dispersed MoO_x than on those originating from polymerized MoO_x species.

通过辅助技术阐明了影响产物选择性的催化剂特性，以及在MoO _x / AlSiO _x上乙烯和反式-2-丁烯向丙烯的复分解反应中，Mo-Carbon物种形成的机理。稳态催化试验表明，导致丙烯形成的反应途径取决于MoO _x物种的类型（高度分散或聚合），MoO _x物种从中原位形成。C ₃ H ₆通过C ₂ H ₄和反式-2-C ₄ H _8的复分解反应直接产生Mo-卡宾化合物上的Mo起源于聚合的MoO _x物种，而1-丁烯和2-丁烯的复分解对于由高度分散的MoO _x形成的Mo-卡宾上的丙烯形成起重要作用。原位FTIR光谱和动力学分析表明，丙烯形成的路径以及相应的选择性取决于C ₂ H ₄与氧化的MoO _x物种和Mo-卡宾反应的能力。该进料组分与高度分散的MoO _x物质的相互作用比与聚合的组分之间的相互作用更弱。此外，C ₂ H ₄在由高度分散的MoO _x形成的Mo-卡宾上的吸附更强而不是源自聚合的MoO _x物种。