Active size-controlled Ru catalysts for selective CO oxidation in H2

We propose an activation method to control Ru particle size in supported Ru catalysts, viz. commercial Ru/Al2O3 and home-made Ru/SiO2, in order to increase the catalytic activity for the preferential CO oxidation (PROX). Ru particle size is controlled by adjusting pre-treatment conditions and it affects the catalytic activity for the PROX over supported Ru catalysts. Several measurements: inductively coupled plasma-atomic emission spectroscopy (ICP-AES), bright-field transmission electron microscopy (TEM), X-ray absorption fine structure (XAFS), CO chemisorption, and O2 chemisorption were conducted to characterize the catalysts. The co-presence of H2 and O2 is essential for controlling the Ru particle size accurately. The PROX activity especially at low temperatures increases with increasing particle size of Ru, which seems to be closely related to the adsorption behavior of O2 on Ru surface.

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► The Ru dispersion can be controlled through thermal treatment in the presence of H2 and O2.
► There exists an optimum Ru particle size in Ru/Al2O3 for the selective CO oxidation in H2.
► The reduced Ru catalyst is superior to the oxidized one for CO oxidation.