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

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 kWel. 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 Ndm3/(h gcat). The preferential oxidation, which was performed at higher WHSV in the range of 48–98 Ndm3/(h gcat) 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 kWel 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%.