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

2011, Journal of Experimental Nanoscience

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 .