The Characteristics of cobalt, iron and nickel catalysts for the conversion of acetylene and ethylene to higher hydrocarbons

The characteristics of silica-supported iron, cobalt and nickel catalysts for the reactions of acetylene and ethylene in the presence of hydrogen is investigated in the context of a proposal that natural gas could be converted to liquid fuel through pyrolysis to acetylene and then oligomerisation. Under the test conditions used, Ni/SiO₂ is able to completely convert acetylene for long periods with a C₄+ yield of ~45%. Co/SiO₂ exhibits a higher yield initially but deactivates rapidly after an hour or so of operation. Fe/SiO₂ has very low activity, probably due to carbon deposition brought on by the decomposition of acetylene. When ethylene is used, Ni/SiO₂ is both very active and stable but exhibits excessive hydrogenation with an ethane yield exceeding 95%. Fe/SiO₂ is less active and also produces largely ethane. Co/SiO₂ is very active initially and capable of oligomer yield of at least 40% under some conditions. However its behaviour is highly dependent on test conditions and previous history. The inclusion of small amounts of carbon monoxide in the feed can increase yields but may also induce loss of activity.