(515b) Highly Efficient Methane Reforming over the 0.15wt% Ru/y-Al2O3 Catalyst in the 5um Pd-Ag Film Membrane Reformer

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
[1]. Membrane catalytic reformers can provide high CH₄ conversions below
650°C by selective separation of H₂
(providing also a source of extra-pure H₂) [2], 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 [3]. 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.

[1] Simakov, D. S. A., Wright, M. M., Ahmed, S., Mokheimer E. M. A.
& Román-Leshkov, Y. Solar thermal reforming of natural gas: a review on
chemistry, catalysis and system design. Catal. Sci. Technol. 5, 
1991-2016 (2015).

[2] Said S. A. M., Simakov D. S. A., Mokheimer E. M. A., Habib M. A.,
Ahmed, S., Waseeuddin M. & Román-Leshkov Y. Computational fluid dynamics
study of hydrogen generation by low temperature methane reforming in a membrane
reactor. Int. J. Hydrogen Energy. 40, 3158?3169 (2015).

[3] Simakov, D. S. A., Luo H. Y. & Román-Leshkov, Y. Ultra-low
loading Ru/g-Al₂O₃: a highly active and
stable catalyst for low temperature solar thermal reforming of methane. Appl.
Catal. B: Environ. 169, 540?549 (2015).