A photoacoustic spectroscopy technique was employed to the kinetic study of the CO2/CH4 reaction catalyzed by Ni particles embedded into the mesochannels of SBA15. The catalytic CO2/CH4 reaction was performed in a closed-circulating reactor system at various partial pressures of CO2 and CH4 (40 Torr total pressure) in the temperature range of 500-700 °C. The CO2 photoacoustic signal that varied with the concentration of CO2 during the catalytic reaction was recorded as a function of time by using a differential photoacoustic cell. Under the reaction conditions, the CO2 photoacoustic measurements showed the SBA15 compound used as support to be inactive for the reaction. The CO2/CH4 reaction carried out in the presence of the H2-reduced Ni/SBA15 catalyst showed significant time-dependent changes in the CO2 photoacoustic signal, while the reaction performed in the presence of the as-prepared Ni/SBA15 catalyst did not. The CO2 photoacoustic signal obtained at early reaction times provided precise data of the CO2 disappearance rate. The rate of CO2 disappearance was observed to increase with increasing temperature in the range of 500-700 °C. The apparent activation energy for the CO2 consumption in the Ni/SBA15 catalyzed reaction was calculated to be 6.2 kcal/mol. Reaction orders, determined from initial rates of CO2 disappearance at various PC O2's and PC H4's at 700 °C, were found to be 0.28 for CH4 and 0.39 for CO2, respectively. The kinetic results were compared with those previously reported and were used to infer a catalytic reaction mechanism for the CO2/CH4 reaction at low pressures.
Bibliographical noteFunding Information:
This work was supported by grant No. 2006-000-10330-0 from the Basic Research Program of the Korea Science & Engineering Foundation, and the Brain Korea 21 Project of the Ministry of Education, Science and Technology of Korea .
All Science Journal Classification (ASJC) codes
- Process Chemistry and Technology