SYNTHESIS OF KETENES WITH OXIDE CATALYSTS

Design principles elucidated from surface science studies of carboxyli c acid chemistry on oxide surfaces were applied to the synthesis of ke tenes by catalytic dehydration. High surface area silicas were found t o produce C-2-C-5 ketenes from the corresponding carboxylic acids abov e 700 K in both temperature-programmed desorption and steady-state cat alysis experiments. Ketene selectivities of 35-85% on a carbon basis w ere obtained, with CO2 and ketones as the principal side products. The activity for ketene production tracks catalyst surface area and hydro xyl population, and a catalytic cycle involving surface hydroxyls as a ctive sites is proposed. This one-step catalytic route to ketenes offe rs potential reduction of operating temperature, complexity, solvent u tilization and/or byproduct formation relative to currently practiced, noncatalytic technologies.