Highly efficient methane reforming over the 0.15wt% Ru/y-Al2O3 catalyst in the 5um Pd-Ag film membrane reformer
David S. A. Simakov and Yuriy Román-Leshkov
Department of Chemical Engineering, MIT, Cambridge MA 02139, USA
Natural gas is an abundant, cheap and relatively clean source of energy and chemical feedstocks, which can be reformed to syngas (CH4 + H2O = CO + 3H2), requiring however temperatures above 850°C . Membrane catalytic reformers can provide high CH4 conversions below 650°C by selective separation of H2 (providing also a source of extra-pure H2) , but highly active and stable catalysts are required. Commercial Ni-based catalysts do not have sufficient activity at these temperatures and deactivate rapidly by coking, particularly at (highly desirable) low steam/carbon ratios. In our recent work we have demonstrated that the ultra-low loading 0.15wt% Ru/y-Al2O3 catalyst is highly active in low temperature CH4 reforming and has excellent stability at low steam/carbon ratios . Herein, we demonstrate the implementation of this catalyst in a membrane reformer, using the supported 5um Pd-Ag film membrane for H2 separation. Conversions well above the equilibrium were achieved (Fig. 1a), generating 3.5 mol of ultra-pure H2 per mol of CH4 fed at the maximum (Fig. 1b). Importantly, the maximal power density of this (6 inch length, 0.5 inch OD) unit was 0.9kW/L (if the H2 generated is fed to a 60% efficient fuel cell). No significant deactivation was observed after 200h of operation. The feasibility of the low steam/carbon ratio (S/C=1, 2) and of dry (CO2) reforming was also investigated.
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