Despite more than two decades of research in the area, a commercially viable fuel processor for hydrogen production for PEM fuel cells has yet to be developed. The present work begins with a modeling study of fuel processor/fuel cell systems. Integration of the fuel processing reactor into the overall system was studied, and variables affecting processor size and system efficiencies identified. An autothermal reforming (ATR) Pd membrane reactor was shown to offer potential for high productivity and efficiency in a compact design. Both liquid hydrocarbons and methanol were studied as feedstocks, and methanol was chosen for a more detailed analysis.;An experimental study of methanol ATR, guided by modeling, was conducted. Mass transfer limitations at the pellet level were predicted to be significant under methanol reforming conditions. Simulations of an adiabatic reactor showed that the exothermic oxidation reaction is much faster than the endothermic reforming reaction. This imbalance in reaction rates leads to excessive catalyst bed temperatures in an adiabatic reactor. This problem was mitigated by distributing the air injection axially within the catalyst bed through porous ceramic fibers. An adiabatic laboratory ATR reactor was built and tested using this design. Simultaneous measurements of the steady-state temperature and composition axial profiles afforded the reactor model validation. Next, an isothermal single-fiber membrane reactor was built and tested under methanol steam reforming conditions. Porous alumina fiber-supported Pd/Ag alloy membranes prepared in-house in a related program were used. Performance characteristics of this membrane under reaction conditions were obtained. The ATR and isothermal membrane models enabled the design and optimization of an adiabatic "dual membrane" ATR reactor for hydrogen production. The study provides guidance for the membrane performance parameters required for a viable membrane reactor fuel processor. Porous ceramic fibers inserted through one end of the reactor provide non-selective distribution of air along the length of the oxidation zone of the reactor, while Pd/Ag membranes inserted through the other end provide selective hydrogen separation in a reforming zone. The results reveal that a maximum Pd/Ag membrane thickness of 4.6 mum is required to achieve the target productivity of 100 mol H2.m-3.s-1.
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