Carbon monoxide oxidation in a packed bed reactor with copper chromite catalyst

Abstract

As a basic study for controlling automobile exhaust gas, the copper chromite catalysts which have higher intrinsic activity and higher resistance to thermal sintering were prepared, and the properties were checked after thermal treatment. The effects of the operating conditions on reaction rates of carbonmonoxide in a packed bed reactor and reaction kinetics were investigated. X-ray diffraction spectra of the catalysts showed that the mixed type catalyst contained CuO and $CuCr_2O_4$ and the spinel type catalyst which was prepared by leaching to remove exess CuO from the mixed type with a 6M hydrochloric acid solution contained only $CuCr_2O_4$. The surface area determined by the Brunauer, Emmett, and Teller method using $N_2$ at liquid nitrogen temperature was 7$m^2$/g. After thermal treatment at 600$^\circ$C for 4 hours and at 850$^\circ$C for 24 hours, the catalytic activity changes in both temperatures were checked. The activity of the spinel type decreased about 30\% by treatment at 800$^\circ$C for 24 hours. It was observed from the X-ray diffraction spectrum that the degradation of activity in carbon monoxide oxidation came from the formation of cuprous chromite($Cu_2Cr_2O_4$). The catalytic activity of carbon monoxide oxidation reaction over spinel type copper chromite did not nearly change for 24 hours under a normal operating condition without $SO_2$. The reaction was carried out of various operating conditions to study the catalytic activity. The reaction rate increased as the reaction temperature and the concentration of reactants increased and the inhibition effect of carbon dioxide on the reaction rate could be neglected at above 150$^\circ$C. The reaction kinetics for the oxidation of carbon monoxide over spinel type copper chromite could be interpreted by the simple empirical power model. The exponents of partial pressures of CO and $O_2$ in the rate equation were 0.6 and 0.9, respectively, and the activation energy and the frequency factor were...