Steam reforming of methanol over ceria and gold-ceria nanoshapes

In this work we have found that a small amount (similar to 1 at.%) of gold deposited on ceria nanorods exhibits excellent catalytic activity for the low-temperature steam reforming of methanol (SRM). Gold clusters (<1 nm, TEM invisible) dispersed on the {110} faces of ceria nanorods catalyze the reaction in a cooperative mechanism with ceria. Gold nanoparticles (similar to 3 nm) on the {100} surfaces of ceria nanocubes are inactive. The apparent activation energy of the SRM reaction on Au-ceria is similar to 110 kJ mo1(-1). On the basis of TPSR/MS analysis, we determined that the SRM reaction on Au-ceria involves methanol dehydrogenation, methyl formate hydrolysis and formic acid decomposition steps to produce CO2 and H-2. Better than 97% catalyst selectivity to CO2 was found over the temperature range from 175 to 250 degrees C. In the presence of methanol, the water-gas shift (WGS) reaction is suppressed and is not part of the mechanism at temperatures below 250 degrees C. The SRM stability of the Au-ceria system is good for practical application of this type catalyst. (C) 2009 Elsevier B.V. All rights reserved.