Abstract
The system of 2-propanol-acetone-hydrogen can be effectively utilized as a chemical heat pump cycle. This research focuses on an important part of the cycle, specifically the liquid-phase dehydrogenation of 2-propanol to produce acetone and hydrogen at low temperatures under boiling conditions. As preliminary experiments, the reaction rate in the vapor phase was measured in a fixed-bed reactor filled with Ru-Pd/C catalyst which had high selectivity and activity for dehydrogenation. The conversion was limited by the equilibrium (0.108 at 90°C). Next, since the product acetone is known to be a strong inhibitor in the dehydrogenation, a reactive distillation column was used to separate acetone from the reaction field. Acetone (b.p. 56.3°C) is vaporized as the top product ahead of 2-propanol (b.p. 82.4°C). The hydrogen produced remains in the gas phase throughout the operation. The use of reactive distillation, which is a pioneering idea for this chemical heat pump, can facilitate complete conversion of the dehydrogenation. Pure acetone can be obtained for the specified conditions (less than 0.04 mmol/s of feed flow rate). The conversion was greatly affected by the feed flow rate, the temperature of the heat source, and the reflux ratio. The reaction rate is independent of the mole fraction of acetone in the feed. The proposed reactive distillation may be promising for a chemical heat pump.
