OXYGENATES FROM SYNGAS OVER HIGHLY DISPERSED COBALT CATALYSTS

Highly dispersed cobalt metal catalyst has been prepared by the deposi tion of Co-2(CO)(8) on silicagel in an oxygen-free condition and has b een characterized with EXAFS. This catalyst exhibited high activity fo r the formation of C-2(+) oxygenates from syngas without any modificat ion. The formation of hydrocarbons was strongly suppressed and the sel ectivity of oxygenates, especially C-2-oxygenates, was enhanced by the modification with alkali or alkaline earth cations. From the modifica tion effects on CO hydrogenation and by the studies of in situ FT-IR, these basic cations were considered to reduce the hydrogenating abilit y of the catalyst by controlling the electronic state of the active co balt site. Noble metals such as iridium and ruthenium have little effe ct on the catalyst of CO hydrogenation. Similar cobalt catalysts were prepared from Co-2(CO)(8) on other oxide supports and some oxides show ed a similar effect on the basic additives. The effect of the cations and the reaction mechanism for the formation of oxygenates were discus sed.