Kinetic studies of methanol dehydrogenation. Part I: copper-silica catalysts

A series of Cu/SiO2 catalysts was prepared using incipient wetness impregnation of silica gel with an aqueous solution of copper nitrate. The copper loading was 5 wt%. After the calcination, the catalyst was reduced in a hydrogen flow at varied temperatures (200, 300, and 400 A degrees C). A conventional fixed bed reactor system was used to study the kinetics of methanol dehydrogenation to methyl formate. Methyl formate decomposition to carbon monoxide and hydrogen was taken into account as a main side reaction. Observable rate constants were determined. The temperature of reductive pretreatment of the catalysts was shown to affect strongly their catalytic behavior in the studied reaction. The highest methyl formate yield was achieved for the sample reduced at 200 A degrees C. An increase of reduction temperature up to 400 A degrees C worsens the selectivity towards the main product in approximately by a factor of 2. The kinetic parameters obtained were used for modelling the process in a tubular reactor. Good agreement of theoretical and experimental data was found.