Comparison of reticulated ceramic foam to packed bed porous media reactors for conversion of methane to hydrogen

This study compared the fuel reforming characteristics of a reticulated ceramic reactor to a packed bed reactor through experimental and computational analysis. The reticulated ceramic reactor consisted of 3.9 pores per centimeter (ppc) yttria stabilized zirconia (YZA) and the packed bed reactor consisted of 3 mm diameter aluminum oxide pellets. Both reactor designs and experimental procedures were identical to ensure comparable results. Exhaust gas concentrations and temperatures were measured for experiments run over an equivalence ratio range of 2 to 5. For both reactors, the peak conversion of methane to hydrogen occurred at an equivalence ratio of 2.5. Hydrogen production and percent conversion were significantly better for the reticulated ceramic reactor than the packed bed reactor when compared based on interstitial velocity. The computational model showed that the improved percent conversion in the reticulated ceramic reactor was primarily due to improved steam reforming. The steam reforming was enhanced due to higher temperatures downstream of the combustion zone. Material properties of the porous media had an effect on the greater percent conversion in the reticulated ceramic reactor. The largest effect was from the lower volumetric heat transfer coefficient in the reticulated ceramic. A small study into the effectiveness of a FeCrAlY reticulated metal reactor showed the inability of the FeCrAlY material to withstand high temperatures. The degradation of the FeCrAlY prevented the material from being useful in fuel reforming applications.