Combined CO2 reforming and partial oxidation of methane over mesoporous nanostructured Ni/M-Al2O3 catalyst: Effect of various support promoters and nickel loadings

Abstract

In this research, cerium and zirconium were used as alumina support promoters for nickel-based catalysts to improve the metal dispersion and reduce the carbon formation in the methane combined reforming process. The mechanochemical and impregnation methods were used to prepare the supports and catalysts, respectively. BET, XRD, TPR, TPO, and FESEM analyses were performed to characterize the prepared catalysts. According to the results, all the synthesized catalysts had high BET area and mesoporous structure, and the pore size distributions were in the range of 2–12 nm. Adding cerium and zirconium improved the nickel dispersion and raised the interaction between nickel and support. The sample promoted with cerium oxide decreased the amount of deposited carbon over the catalyst surface in the methane dry reforming and exhibited the highest activity in the combined reforming. However, the addition of oxygen significantly reduced the amount of carbon formation over the catalyst surfaces. Moreover, the outcomes indicated that the catalyst with 10 wt% of nickel with the highest specific surface area (195 m2.g−1) possessed the best performance. The 10 wt%Ni/Al2O3-10%CeO2 catalyst was stable for 440 min at 700 °C, and the CH4 and CO2 conversion reached 79% and 60% in the combined reforming process at this temperature. In addition, the influence of the operating parameters such as gas hourly space velocity, feed ratio, and reduction temperature were also investigated on the catalyst efficiency of the selected sample.