Effect of the Nature of the CeO 2 Support of the Rh Catalyst on Triggering the Oxidative Reforming of n ‐Butane for H 2 Production from Ambient Temperature

Three Rh catalysts supported on CeO 2 with different specific surface areas and redox properties were prepared and evaluated for their ability to trigger the oxidative reforming of n ‐butane from ambient temperature (≈300 K). The reference CeO 2 catalysts supplied by the Catalyst Society of Japan (JRC‐CEO‐1, ‐3, and ‐4) were used as supports. Temperature‐programmed reduction and O 2 titration measurements over the reduced catalysts indicated that a high number of surface CeO 2 sites that were reducible below 573 K were present on the Rh/CEO‐3 catalyst; this catalyst had the largest specific surface area, and it generated sufficient heat by oxidizing CeO 2− x [Δ H (298 K)=−368 kJ; x =0.5] after H 2 reduction at 773 K. Furthermore, the temperature‐programmed reactions revealed that forming fine Rh particles on the high surface area of CEO‐3 lowers the autoignition temperature (498 K) of the oxidative reforming of n ‐butane because the number of exposed Rh sites initiating reactions between n ‐butane and O 2 is large. Thus, the Rh/CEO‐3 catalyst could trigger the oxidative reforming of n ‐butane at ambient temperature after H 2 reduction at 773 K owing to the heat generated by the spontaneous oxidation of CeO 2− x . In contrast, other catalysts could not trigger the reaction after reduction at the same temperature.