Comparison of Different Concepts for Solar Reforming of Natural Gas

Abstract

Solar redox reforming of methane is investigated and compared to heterogeneously catalyzed solar reforming. An analysis of potential redox materials based on material prices and thermodynamic calculations yields iron oxide and ceria as promising candidates for redox reforming. Steam and dry methane reforming were studied for both materials, by process simulations in Aspen Custom Modeler. Models for heterogeneously catalyzed steam and dry methane reforming were used as reference processes. In total, six models were developed and used for the simulations. The impact of heat recovery between the redox material in the oxidized and the reduced state is studied. With a solar-to-fuel efficiency of 49.7 % at an oxidation temperature of 823 K, a reduction temperature of 1190 K and a corresponding pressure of 30 atm, redox steam methane reforming with iron oxide is the only redox cycle that is competitive with the reference process, in terms of efficiency. Redox steam methane reforming with iron oxide and redox dry methane reforming with ceria can produce high purity H2 and CO, respectively. No carbon formation was observed at those points of operation that lead to high solar-to-fuel efficiencies