(181d) Studies for a Catalytically Heated Hexadecane Steam Reformer

Reforming of diesel fuels for hydrogen generation for fuel cell systems is advantageous due to the availability of diesel fuel, the possible application in auxiliary power unit generators and the still growing market segment of diesel cars in Europe. Microchannel reactors offer high heat and mass transfer coefficients and are thus able to cope with sudden hydrogen demand i.e. fast start-up and load changes in systems with fluctuating power burden. In the present study we investigated the kinetics of hexadecane reforming and of the consecutive water gas shift reaction by applying an electrically heated microstructured test reactor. The microchannels were coated with a ceria support layer using a sol-gel method [1] and were impregnated with a rhodium catalyst providing good catalyst lifetime and superior coking tolerance compared to our previous results [2]. Based on the results obtained in the electrically heated system a prototype of a microstructured reactor heated by catalytic combustion of e.g. anode off-gas has been designed and built. The system is able to operate in a self-sustaining mode, i.e. to deliver heat for the endothermic steam reforming (at 800°C) and to balance the heat loss. Fig. 1: Hexadecane steam reformer design and reactor under operation (catalytically heated up to 800°C operation temperature) References [1] Haas-Santo, K.; Fichtner, M.; Schubert, K.: Preparation of microstructure compatible porous supports by sol-gel synthesis for catalyst coatings, Applied Catalysis A: 220 (2001), pp 79-92 [2] Thormann, J.; Pfeifer, P.; Kunz, U.; Schubert, K.: Reforming of diesel fuel in a micro reactor for APU systems, Chem. Eng. J. 135S1 (2007) suppl. 1, pp S74-S81