Size of gold particles on preferential oxidation of carbon monoxide

CATL 15

Chuin-Tih Yeh, ctyeh@mx.nthu.edu.tw, Fuel Cell Center, Yuan Ze University, Taoyuan, 32003, Taiwan
Gold particles with size of dAu < 4 nm were deposited on supports of ZnO, TiO2 and Fe2O3 by precipitation of HAuCl3 and reduced to metallic state by H2 flow at 100 oC. The reduced catalysts were used to catalyze preferential oxidation (PROX) of CO in hydrogen rich gas. A synthetic reformate (with 0.5% CO, 48% H2, 24% CO2, 12% H2O and balance N2) was oxidized by small amount of oxygen (with nO2/nCO = 1) in a fixed bed reactor at a GHSV = 6x104 h-1. In a reaction temperature (TR) range between 55 and 100 oC, not only CO but also hydrogen in the synthetic reformate was oxidized in the PROX. However, conversion of CO (CCO) and selectivity of CO oxidation (SCO) varied with kind of gold catalyst, mole ratio of O2/CO and TR of the PROX. Observed CCO and SCO of prepared catalysts generally increased on decreasing dAu of catalysts studied. An excellent SCO > 71% at CCO > 99% was reached by a 1.1 wt% Au/ZnO catalyst with dAu = 1.1 nm.