The cascade reactions of phenylacetylene to ethylcyclohexane and 1-phenyl-1-propyne to propylcyclohexane were studied individually, under deuterium and competitively at 343 K and 3 barg pressure over a Rh/silica catalyst. Both systems gave similar activation energies for alkyne hydrogenation (56 ± 4 kJ mol⁻¹ for phenylacetylene and 50 ± 4 kJ mol⁻¹ for 1-phenyl-1-propyne). Over fresh catalyst the order of reactivity was styrene > phenylacetylene ≫ ethylbenzene. Whereas with the cascade hydrogenation starting with phenylacetylene, styrene hydrogenated much slower phenylacetylene even once all the phenylacetylene was hydrogenated. The activity of ethylbenzene was also reduced in the cascade reaction and after styrene hydrogenation. These reductions in rate were likely due to carbon laydown from phenylacetylene and styrene. Similar behavior was observed with the 1-phenyl-1-propyne cascade. Deuterium experiments revealed similar positive KIEs for phenylacetylene (2.6) and 1-phenyl-1-propyne (2.1). Ethylbenzene hydrogenation/deuteration gave a KIE of 1.6 obtained after styrene hydrogenation in contrast to the inverse KIE of 0.4 found with ethylbenzene hydrogenation/deuteration over a fresh catalyst, indicating a change in rate determining step. Competitive hydrogenation between phenylacetylene and styrene reduced the rate of phenylacetylene hydrogenation but increased selectivity to ethylbenzene suggesting a change in the flux of sub-surface hydrogen. In the competitive reaction between 1-phenyl-1-propyne and propylbenzene, the rate of hydrogenation of 1-phenyl-1-propyne was increased and the rate of alkene isomerization was decreased, likely due to an increase in the hydrogen flux for hydrogenation and a decrease in the hydrogen species active in methylstyrene isomerization.

分别研究了苯乙炔到乙基环己烷和 1-苯基-1-丙炔到丙基环己烷的级联反应，在氘下，在 343 K 和 3 barg 压力下，在 Rh/二氧化硅催化剂上竞争。两种系统都为炔烃加氢提供了相似的活化能（苯乙炔为56 ± 4 kJ mol ^-1，苯乙炔为 50 ± 4 kJ mol ^-11-苯基-1-丙炔）。在新鲜催化剂上，反应性顺序是苯乙烯 > 苯乙炔 ≫ 乙苯。而对于从苯乙炔开始的级联氢化，即使所有苯乙炔都被氢化，苯乙烯氢化苯乙炔的速度要慢得多。在级联反应中和苯乙烯加氢后，乙苯的活性也降低。这些速率的降低可能是由于苯乙炔和苯乙烯的碳沉积。1-苯基-1-丙炔级联也观察到了类似的行为。氘实验揭示了苯乙炔 (2.6) 和 1-苯基-1-丙炔 (2.1) 的类似阳性 KIE。乙苯氢化/氘化后苯乙烯氢化后获得的 KIE 为 1.6，而逆 KIE 为 0。4 在新鲜催化剂上用乙苯氢化/氘化发现，表明速率确定步骤发生了变化。苯乙炔和苯乙烯之间的竞争性氢化降低了苯乙炔氢化的速率，但增加了对乙苯的选择性，表明表面下氢的通量发生了变化。在1-苯基-1-丙炔与丙苯的竞争反应中，1-苯基-1-丙炔的加氢速率增加，烯烃异构化速率降低，可能是由于加氢的氢通量增加和甲基苯乙烯异构化中活性氢物质的减少。苯乙炔和苯乙烯之间的竞争性氢化降低了苯乙炔氢化的速率，但增加了对乙苯的选择性，表明表面下氢的通量发生了变化。在1-苯基-1-丙炔与丙苯的竞争反应中，1-苯基-1-丙炔的加氢速率增加，烯烃异构化速率降低，可能是由于加氢的氢通量增加和甲基苯乙烯异构化中活性氢物质的减少。苯乙炔和苯乙烯之间的竞争性氢化降低了苯乙炔氢化的速率，但增加了对乙苯的选择性，表明表面下氢的通量发生了变化。在1-苯基-1-丙炔与丙苯的竞争反应中，1-苯基-1-丙炔的加氢速率增加，烯烃异构化速率降低，可能是由于加氢的氢通量增加和甲基苯乙烯异构化中活性氢物质的减少。