A micro-structured 5 kW complete fuel processor for iso-octane as hydrogen supply system for mobile auxiliary power units Part II-Development of water-gas shift and preferential oxidation catalysts reactors and assembly of the fuel processor

摘要

Microstructured reactors for water-gas shift and the preferential oxidation of carbon monoxide were developed for a fuel processing/fuel cell system running on iso-octane and designed for an electrical power output of 5 kW_(el).The target application was an automotive auxiliary power unit (APU).The work covered both catalyst and reactor development.A platinum/ceria catalyst was applied for water-gas shift,while platinum on zeolite/alumina carrier served as catalyst for preferential oxidation.These catalysts were introduced into the final full size prototype reactors,which were constructed from microstructured stainless steel foils.Testing in a pilot scale test rig revealed conversion close to the thermodynamic equilibrium for the water-gas shift reactors at a WHSV range of 17-41 Ndm~3/(hg_(cat)).The preferential oxidation,which was performed at higher WHSV in the range of 48-98 Ndm~3/(h g_(cat)) revealed up to 90% conversion in a first stage,while in the second stage reactor the carbon monoxide content of the reformate was decreased to less than 50 ppm.The reactors were then incorporated into a complete bread-board fuel processor of 5 kW_(el) power equivalent,which comprised also of an autothermal reformer reactor.The fuel processor was operated at a steam to carbon ratio of 3.3 and an oxygen to carbon ratio of 0.67.Under these conditions,it converted the iso-octane feed completely to purified reformate with an overall efficiency of 74%.