Non-equilibrium hydrogen production from ethanol using CO2 absorption ceramic and precious metal catalysts

Non-equilibrium H-2 production from ethanol was achieved with precious metal catalysts using a CO2 absorption ceramic. The ceramic consisted of lithium silicate, which was granulated and coated with coarse alumina particles. H-2 production in steam reforming of ethanol was enhanced and CO production was suppressed significantly in the presence of the CO2 absorption ceramic. The optimum temperature region for non-equilibrium H. production was 500-550 degrees C. For example, at a temperature of 500 degrees C, at atmospheric pressure and with a 1 wt% Rh/CeO2 catalyst, the H-2 concentration was 91 mol%-dry, which was considerably higher than that at the chemical equilibrium of 63 mol%-dry, and it was 1.4 times higher than that obtained without the CO2 absorption ceramic. A highest H2 concentration of 96 mol%-dry was obtained at 550 degrees C. The CO concentration decreased dramatically at 500 degrees C from 1.5 mol%-dry to less than the detection limit, which was about 1 x 10(-2) mol%-dry. It was markedly lower than that of the chemical equilibrium. Similar results were also obtained with a I wt% Pt/CeO2 catalyst. At 500 degrees C in particular, the concentration of H-2 was fairly high at 89 mol%-dry and the CO concentration was lower than the detection limit. Carbon deposition was not observed visually in each case. It is concluded that non-equilibrium H-2 production from ethanol with a precious metal catalyst in the presence of the CO2 absorption ceramic has a high potential for application to a non-equilibrium reactor for proton exchange membrane fuel cell (PEMFC) systems. A markedly low concentration of CO and a fairly high concentration of H-2 Will contribute to simplifying the complicated system configuration and to improving PEMFC performance, respectively.