SOLAR REFORMING OF METHANE IN A DIRECT ABSORPTION CATALYTIC REACTOR ON A PARABOLIC DISH .1. TEST AND ANALYSIS

The concept of solar driven chemical reactions in a commercial-scale v olumetric receiver/reactor on a parabolic concentrator was successfull y demonstrated in the CAtalytically Enhanced Solar Absorption Receiver (CAESAR) test. Solar reforming of methane (CH4) with carbon dioxide ( CO2) was achieved in a 64 cm diameter direct absorption reactor on a p arabolic dish capable of 150 kW solar power. The reactor was a catalyt ic volumetric absorber consisting of a multilayered, porous alumina fo am disk coated with rhodium (Rh) catalyst. The system was operated dur ing both steady-state and solar transient (cloud passage) conditions. The total solar power absorbed reached values up to 97 kW and the maxi mum methane conversion was 70%. Receiver thermal efficiencies ranged u p to 85% and chemical efficiencies peaked at 54%. The absorber perform ed satisfactorily in promoting the reforming reaction during the tests without carbon formation. However, problems of cracking and degradati on of the porous matrix, nonuniform dispersion of the Rh through the a bsorber, and catalyst deactivation due to sintering and possible encap sulation, must be resolved to achieve long-tem operation and eventual commercialization.