A study on the properties of modified CuO samples and the kinetics of carbon monoxide oxidation over the given catalysts (original) (raw)

Three catalyst samples 10 wt% CuO/-Al 2 O 3 (CuAl), 10 wt%CuO þ 10 wt% Cr 2 O 3 /-Al 2 O 3 (CuCrAl) and 10 wt%CuO þ 20 wt% CeO 2 /-Al 2 O 3 (CuCeAl) have been taken for the study. Physico-chemical characteristics of the catalysts were determined by the methods of BET adsorption, X-ray diffraction and temperature-programmed reduction. Due to a strong interaction of CuO with Al 2 O 3 , resulting in the formation of copper aluminate the catalytic activity of CuO/-Al 2 O 3 has been reduced. The bi-oxide catalyst CuCrAl was more active than CuAl, thanks to the formation of high catalytically active spinel CuCr 2 O 4. The fact of very high activity of the CuCeAl sample can be explained by the presence of the catalytically active form CuO-CeO 2-Al 2 O 3. The kinetics of CO oxidation reaction on the given catalysts was studied at the temperature range between 200 C and 270 C. The values of initial partial pressures of carbon monoxide (P o CO), oxygen (P o O2) and carbon dioxide (P o CO2) were varied in ranges (hPa): 10 Ä 45; 33 Ä 100 and 0 Ä 30, respectively. It has been found that on all the catalysts, the common kinetic equation for the reaction was as follows: r ¼ kP CO P 0:5 O2 ð1 þ k 2 P 0:5 O2 þ k 3 P CO2 Þ , where r is the reaction rate, k is the reaction constant, and k 2 and k 3 are the O 2 and CO 2 adsorption constants, respectively. In the case of CuAl and CuCrAl, k 3 ¼ 0, and since k 2 P 0:5 o2) 1, the equation should become r ¼ k.P CO .