Metal phosphate-supported RuOx catalysts for N2O decomposition

RuOx/M-P-O (M = Mg, Al, Ca, Fe, Co, Zn, La) catalysts were prepared by impregnating commercial metal phosphates with RuCl3, followed by calcination in air at 500 degrees C. The catalytic performance in N2O decomposition was studied. Among these catalysts, RuOx/Ca-P-O (also denoted as RuOx/HAP, HAP = hydroxyapatite) showed the highest activity, achieving complete N2O conversion at 400 degrees C. RuOx/Mg-P-O was the second most active, showing 46.3% N2O conversion at 400 degrees C. The presence of 5.0 vol.% O-2 or 2.0 vol.% H2O in the reaction mixture inhibited the catalytic activity of RuOx/HAP to some extent, but the inhibiting effect was reversible, i.e., the activity was restored after O-2 or H2O was retracted. The influences of pretreatment by H-2 as well as different Ru-containing precursors on the catalytic performance of RuOx/HAP were also studied. The characterization data indicate that RuOx/HAP has a not-so-small surface area (49.5 m(2)/g), highly dispersed amorphous RuOx species, as well as relatively abundant basic sites, O-2-adsorption sites, and surface hydroxyls. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.