Highly active subnano Rh/Fe(OH)x catalyst for preferential oxidation of CO in H2-rich stream

Abstract A novel catalyst formulation of 3.1 wt.% Rh/Fe(OH) x was prepared via a co-precipitation method and investigated for CO preferential oxidation in H 2 -rich stream. This catalyst exhibited a wider temperature range of 20–70 °C for CO total removal and better resistance to CO 2 and H 2 O compared with the standard gold catalyst, standing out as the best Rh-based catalyst ever. The Rh species were highly dispersed in a subnano scale of ∼1 nm and improved the reducibility of Fe(OH) x support. The adsorption of O 2 was thus promoted over the reduced support, together with the weakened CO adsorption over the Rh clusters, permitting a non-competitive Langmuir–Hinshelwood mechanism through the elementary reaction of CO (ad)  + O (ad) . The reaction rate equation of r  =  k [CO] 0.73 [O 2 ] 0.64 and small apparent activation energy of 24 kJ mol −1 were then derived from the kinetic studies.