Characterization of Ca-promoted Co/AC catalyst for CO2-CH4 reforming to syngas production

- Addition of Ca catalyst at optimum amount enhances activity and stability.
- High activity of Co-Co/AC catalyst due to a new crystal substance Ca3Co2O6 formed.
- Ca improves the Co dispersion enhances activity and stability.
- Strong Ca-Co interaction on Co-Co/AC catalyst prevents metal sintering.
- High metal sintering resistance leads to high catalytic stability.

Ca-promoted Co-based/AC catalysts prepared with various Ca/Co ratios by using impregnation method were applied to synthesis gas production via CO2-CH4 reforming reaction. The influences of preparation methods on the physico-chemical characteristics, catalytic activities and stability of the catalysts were examined in a fixed-bed reactor. The basic physico-chemical characters of prepared catalysts were studied by the H2-TPR, XRD and XPS and BET methods. H2-TPR, XRD and XPS results confirmed that cobalt dispersion improving, the interaction between cobalt and calcium intensify and the sintering of cobalt mitigation is due to calcium addition. Results of XRD and H2-TPR also show that there was a new crystal substance Ca3Co2O6 formed, which has most strong influence on the catalytic activity enhancing and the anti-coking ability of CO2-CH4 reforming catalyst. Through the SEM analysis of the used catalyst after CO2-CH4 reforming, the Co-Ca/AC catalysts were also confirmed to show better sinter-stability. In addition, the addition of calcium can improve the carbon dioxide adsorption properties, so that it is easy to eliminate carbon deposited on the surface of the catalyst by gasification. In particular, the catalyst with 14 wt.% of calcium addition revealed a good activity and anti-sintering ability in CO2-CH4 reforming. On the basis of experimental observations and literature reviewed, a simple carbon dioxide reforming of methane into syngas mechanism over a cobalt/AC catalyst promoted by Ca is proposed.

The reducibility of the Co-Ca/AC catalyst decreased and the Co dispersion improved due to the strong interaction between Co and Ca species. Ca can promote the formation of Ca3Co2O6 which are postulated to play an important role in the carbon dioxide reforming of methane.151