15min:

B. S. LIU, Department of Chemistry, Tianjin University Tianjin 300072, P.R. China and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong; J. W-H. LEUNG, LING LI AND A. S-C. CHEUNG, Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong; C. T. AU, Department of Chemistry and Center for Surface Analysis and Research, Hong Kong Baptist University, Kowloon Tong, Hong Kong.

The catalytic reaction of CO₂ reforming of CH₄ produces synthesis gas (CO and H₂), which is useful as a feedstock for many industrial processes. In the past few years, many transition metal-based catalysts have been investigated but the major problems reported were catalytic deactivation due to carbon deposition and low yield. We studied the CH₄/CO₂ reforming over La₂NiO₄ and 10%NiO/CeO₂-La₂O₃ catalysts under the condition of supersonic jet expansion via direct monitoring of the change in reactants (CH₄ and CO₂), product (CO) and side-product (H₂O) using the sensitive technique of cavity ring-down spectroscopy. Vibration-rotational absorption lines of CH₄, H₂O, CO₂ and CO molecules were recorded in the near infrared spectral region. We found that La₂NiO₄ is superior to 10%NiO/CeO₂-La₂O₃ in performance. We have also investigated the associated reverse water-gas shift (RWGS) reaction, which affects significantly the H₂/CO product ratio, over the catalysts during CH₄/CO₂ reforming. Our results indicated that the RWGS reaction promoted the conversion of CO₂ and decreased the partial pressure of hydrogen. By proper adjustment of the pressure of the reaction system, it is possible to suppress the occurrence of RWGS reaction and increase the selectivity of CH₄/CO₂ reforming.