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

摘要

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 CO _2/H _2 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 H _2 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 CO _2 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 CO _2/H _2), whereas butyl formate primarily decomposed via decarbonylation (to CO/butanol). When water was present, the formate ester hydrolyzed, which increased the selectivity toward CO _2 and H _2.