Abstract
Hydrogen H_2 for fuel-cell power plants is commonly manufactured from hydrogen-rich materials such as hydrocarbons C_nH_m and alcohols C_oH_p(OH)_q, using steam-reforming methods with catalysts. Recently, the authors have investigated the optimum conditions for efficient and endurable steam reforming (Shinoki et al., 2011). Specifically speaking, experiments are conducted with Cu/ZnO/Al_2O_3 catalyst. Using a household-use-scale reactor with well-controlled temperature distribution, the authors have shown that the Cu/ZnO/Al_2O_3 catalyst has rather high performance with high hydrogen concentration C_<H2> at low values of reaction temperature T_R. In the present study, the authors investigate the optimum conditions as well as Shinoki et al., especially focusing on both the influences of liquid-hourly space velocity LHSV upon concentrations such as C_<H2>, C_<CO2>, C_<CO> and C_<CH4> and the influence of LHSV upon the ethanol conversion X_<C2H5OH>, in a wide range of LHSV at several S/C's and at several T_R's. As a result, all the concentrations are close to the theory of Shinoki et al. except for the case at low T_R and high LHSV. To settle the inconsistency of this exceptional case, the authors propose a new theory using some chemical reactions related with acetaldehyde CH_3CHO. Furthermore, the authors discuss the influences of T_R in addition to LHSV.
