The development of microreactors for the catalytic reforming of fuels, such as methanol and hydrocarbons, for on-site H2 production has grown rapidly in the past few years. The challenges encountered in the reforming of fuels are: (i) to avoid coking of the catalyst by operating at temperatures greater than 800 °C; (ii) to achieve high conversion in a small reactor volume; and (iii) to minimize the pressure drop across the reactor. A suitable microreactor, to meet these challenges, must be compatible with high operating temperatures, have a high surface area-to-volume ratio, and have a high porosity.

To meet these requirements, we have fabricated highly porous inverted beaded catalyst support structures made from silicon carbide (SiC) and silicon carbonitride (SiCN) [1], and have integrated these structures within high-density, non-porous alumina housings. The integrated ceramic microreactors show excellent thermal and chemical stability up to 1200 °C in air, and the SiC or SiCN support structures have geometric surface areas between 105 and 108 m2/m3. These catalyst support structures have a void fraction of 0.74, significantly reducing the pressure drop compared to packed catalytic beds. Additionally, the channeling of reactants occurring with packed particles is avoided by the use of these inverted beaded porous monoliths. We will show our efforts in the fabrication and characterization of the SiC and SiCN porous structures, and their integration into alumina reactor housings. We will also show the conversion data for these integrated ceramic microreactors at temperatures up to 1000 °C for the decomposition of ammonia and the steam reforming of propane at temperatures above 800 ºC.

[1] Fabrication of macroporous SiC and SiCN materials for high temperature microreactors, I.-K. Sung, Nfn. Christian, M. Mitchell, D.-P. Kim, P.J.A. Kenis, Advanced Functional Materials, 2005, 15, 1336-1342.