Catalytic Performance of Lanthanum Promoted Ni/ZrO₂ for Carbon Dioxide Reforming of Methane

• Main Authors: Mahmud S. Lanre, Ahmed S. Al-Fatesh, Anis H. Fakeeha, Samsudeen O. Kasim, Ahmed A. Ibrahim, Abdulrahman S. Al-Awadi, Attiyah A. Al-Zahrani, Ahmed E. Abasaeed
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: Processes
• Subjects: catalyst stability; lanthanum promoters; methane dry reforming; nickel catalyst; zirconium oxide
• Online Access: https://www.mdpi.com/2227-9717/8/11/1502

Nickel catalysts supported on zirconium oxide and modified by various amounts of lanthanum with 10, 15, and 20 wt.% were synthesized for CO₂ reforming of methane. The effect of La₂O₃ as a promoter on the stability of the catalyst, the amount of carbon formed, and the ratio of H₂ to CO were investigated. In this study, we observed that promoting the catalyst with La₂O₃ enhanced catalyst activities. The conversions of the feed, i.e., methane and carbon dioxide, were in the order 10La₂O₃ > 15La₂O₃ > 20La₂O₃ > 0La₂O₃, with the highest conversions being about 60% and 70% for both CH₄ and CO₂ respectively. Brunauer–Emmett–Teller (BET) analysis showed that the surface area of the catalysts decreased slightly with increasing La₂O₃ doping. We observed that 10% La₂O₃ doping had the highest specific surface area (21.6 m²/g) and the least for the un-promoted sample. The higher surface areas of the promoted samples relative to the reference catalyst is an indication of the concentration of the metals at the mouths of the pores of the support. XRD analysis identified the different phases available, which ranged from NiO species to the monoclinic and tetragonal phases of ZrO₂. Temperature programmed reduction (TPR) analysis showed that the addition of La₂O₃ lowered the activation temperature needed for the promoted catalysts. The structural changes in the morphology of the fresh catalyst were revealed by microscopic analysis. The elemental compositions of the catalyst, synthesized through energy dispersive X-ray analysis, were virtually the same as the calculated amount used for the synthesis. The thermogravimetric analysis (TGA) of spent catalysts showed that the La₂O₃ loading of 10 wt.% contributed to the gasification of carbon deposits and hence gave about 1% weight-loss after a reaction time of 7.5 h at 700 °C.