Activated takovite catalysts for partial hydrogenation of ethyne, propyne, and propadiene

摘要: The gas-phase hydrogenation of ethyne, propyne, and propadiene was investigated over partially reduced Ni–Al mixed oxides derived from takovite, a hydrotalcite-type compound. unique attributes the hydrotalcite route leads to more active selective catalysts compared conventional Ni/Al2O3 prepared by impregnation. Tuning calcination reduction conditions catalyst precursor is essential optimize performance. best catalyst, calcined at 773 K, rendered stable propene yields up ca. 65% consisted Ni(Al)Ox solid solution with 55% total bulk nickel in form surface enrichment aluminum. Sintering NiO crystallization NiAl2O4 high temperature induce lower activity. alkyne or diene conversion increases percentage metallic Ni samples, while an optimal degree maximizes monoalkene selectivity. Below optimum, oligomer formation favored above alkane production increases. A similar pattern found for H2/HC ratio. alkene selectivity experiences dramatic increase early stages reaction, which correlated build-up C-containing species on (sub-)surface. These selectivity-enhancing are formed specific reaction temperatures, highlighting relevance testing procedure assessing catalysts. catalytic performance strongly influenced hydrocarbon substrate. In contrast propyne propadiene, ethyne led C2H4 yield only 6%.