Reaction kinetics studies of the conversions of formic acid and butyl formate over carbon-supported palladium in the liquid phase

Formic acid and butyl formate conversion were studied in the liquid phase over Pd and Ru catalysts. Pd/C was more active, selective, and stable for CO2/H2 production in the liquid phase. Kinetic studies were performed over Pd/C at temperatures from 403 to 443 K, at space velocities from 3.8 to 970 h−1, in the presence of CO and H2 at partial pressures from 0 to 0.4 and 12.6 atm, respectively, and liquid water. Space velocity studies probed the importance of primary decomposition pathways to CO2 and CO compared to the secondary water–gas shift reaction. Generally, the rate of the primary pathway was an order of magnitude higher than the rate of the secondary pathway. Over Pd/C, formic acid decomposed primarily via decarboxylation (to CO2/H2), whereas butyl formate primarily decomposed via decarbonylation (to CO/butanol). When water was present, the formate ester hydrolyzed, which increased the selectivity toward CO2 and H2.