Industrial & Engineering Chemistry Research, Vol.33, No.12, 2904-2912, 1994
Synthesis of Ketenes with Oxide Catalysts
Design principles elucidated from surface science studies of carboxylic acid chemistry on oxide surfaces were applied to the synthesis of ketenes by catalytic dehydration. High surface area silicas were found to produce C-2-C-5 ketenes from the corresponding carboxylic acids above 700 K in both temperature-programmed desorption and steady-state catalysis experiments. Ketene selectivities of 35-85% on a carbon basis were obtained, with CO2 and ketones as the principal side products. The activity for ketene production tracks catalyst surface area and hydroxyl population, and a catalytic cycle involving surface hydroxyls as active sites is proposed. This one-step catalytic route to ketenes offers potential reduction of operating temperature, complexity, solvent utilization and/or byproduct formation relative to currently practiced, noncatalytic technologies.
Keywords:ACETIC-ACID;CARBOXYLIC-ACIDS;MAGNESIUM-OXIDE;HYDROXYL-GROUPS;SINGLE-CRYSTAL;DECOMPOSITION;SURFACES;SILICA;ACETALDEHYDE;TIO2