Sorption Enhanced Steam Reforming of Propane Using Calcium Looping

Abstract

Sorption enhanced steam reforming of propane over Ni catalyst using in-situ carbonation of CaO provides both carbon capture, and enhanced H2 content in the product gas, and enhanced carbon conversion efficiency. Choosing propane over methane for sorption enhanced reforming provides easier fuel handling capability and higher throughput of H2 per unit volume of fuel. Such advantages help in building domestic scale hydrogen production source for sustainable energy production. The effect of propane addition on CaO carbonation and poisoning possibilities in reformation integrated with CO2 capture is explored in a packed-bed reactor. The motivation of propane addition is to model petroleum gas to address the feasibility of carbon capture integration with hydrocarbon reforming processes. Initially, different partial pressures of steam and propane will be used to study the kinetic parameters in a fixed bed reactor at different temperatures. The formed kinetic models will be used to compare the integrated CO2 capture results and the thermodynamic results to evaluate the efficiencies of such process. Higher temperatures provide better conversion efficiency, but the equilibrium of CaO carbonation suggests steam reforming enhancement and CO2 capture needs to be below 1073 K in order to avoid the backward reaction of CaCO3 releasing CO2. The balance between endothermic reformation reaction and exothermic water-gas shift and CaO carbonation reactions is the optimizing parameter for improved conversion to high H2 content. Temperatures higher than 873 K provided higher conversion with lower CO2 capture and H2 content while lower than 873 K provided lower methane conversion and higher CO2 capture and H2 content. Increase in steam to carbon ratio increased CH4 conversion and reduced CO content without affecting sorption with no further reduction in CO2 observed for most of the sorption cycle. These results supplement the available data in the literature to provide superior reaction conditions to improve the process efficiency in hydrogen production.