Effect of support composition and metal loading on Au/Ce1−xZrxO2 catalysts for the oxidative steam reforming of methanol

Abstract

Gold (Au) deposited on CeO2–ZrO2 mixed oxides, prepared by the co-precipitation (CP) technique, was tested for oxidative steam reforming of methanol (OSRM) in the temperature range of 200–400°C. An active uniform Ce1−xZrxO2 solid solution was found to be dependent on the Zr/(Ce+Zr) ratio and the calcination temperature of the support, where a ratio of 0.25 calcined at 400°C efficiently performed Zr4+ incorporation inside the Ce4+ lattice to produce smaller ceria crystallites and higher surface area. The highest methanol conversion obtained was 92% at 400°C, while H2 and CO concentrations were observed at 16% and 0.25%, respectively. The variation in Au content significantly affected the Au particle size, where Au agglomeration appeared at the highest loading of 5wt%, while the 3wt% Au had optimum particle size at 21nm, which was suitable for OSRM. When comparing the stability behaviors of the Au/CeO2 and Au/Ce0.75Zr0.25O2 catalysts at 350°C, the solid solution supports had higher catalytic activity with a longer life-time and less coke formation via coke gasification, as the main factor of catalyst deactivation, than those of the Au/CeO2 catalyst.