High-density conversion of light energy via direct illumination of catalyst

Steam reforming of methane was studied under direct illumination of a catalyst by concentrated light in the energy receiver/reactor with a transparent wall. In such a reactor, both the specific rate of hydrogen production and the specific power loading of the light-to-chemical energy conversion appear to increase considerably with respect to a conventional stainless steel reactor, reaching 130 Ndm(3)/h per 1 g of the catalyst and 50-100 W/cm(3), respectively. No considerable photochemical enhancement of the reaction rate was observed. The increase in the reaction rate is supposed to be caused by a significant intensification of energy supply into the catalyst bed due to absorption of light directly by granules of the catalyst used. Moreover, the transparent reactor also showed a higher efficiency of energy conversion because the temperature of the illuminated quartz wall appears to be lower than that for a steel wall which results in lower heat losses. This evidences in clear potentialities of a new generation of ''volumetric'' solar energy receivers/reactors. (C) 1997 International Association for Hydrogen Energy.