Influence of support acidity on CO2 reforming of ethane at high temperature

• Published in: Journal of CO2 utilization 2021-11, Vol.53, p.101713, Article 101713
• Main Authors: Kim, Ki Hoon, You, Young-Woo, Jeong, Min Hye, Jung, Byung Gook, Im, Mintaek, Kim, Young Jin, Heo, Iljeong, Chang, Tae-Sun, Lee, Jin Hee
• Format: Article
• Language: English
• Subjects: CO2 reforming of ethane; Coke; Ethylene; Support acidity; Thermal decomposition
• ISSN: 2212-9820; 2212-9839
• DOI: 10.1016/j.jcou.2021.101713

[Display omitted] •We developed highly stable catalysts for high temperature CO2 reforming of ethane.•Normal catalysts rapidly deactivated due to severe coke formation.•The coke was mainly formed via C2H4 cracking on the acidic sites of the supports.•The control of support acidity by Mg doping greatly suppressed coke deposition. CO2 reforming of ethane (CRE) is an important reaction that produces syngas by utilizing CO2 and shale gas as raw materials. For the industrial production of syngas via CRE, a high temperature reaction is pivotal to secure high productivity and an efficient separation process. The catalytic properties required for high temperature CRE are different from those in low temperature CRE, since ethane is thermally decomposed over 600 ℃. In this study, the CRE reaction was conducted using Ni/Al2O3, Ni/MgAl2O4, and Ni/MgO catalysts at 800 ℃. The blank test revealed that C2H6 was mostly decomposed into C2H4 and H2 at 800 °C, indicating CO2 reforming of C2H4 is the actual reaction pathway. Ni/MgAl2O4 and Ni/MgO exhibited high activity and stability in CRE, while Ni/Al2O3 was deactivated rapidly with a large amount of coke deposition. The various characterizations and coke formation/removal experiments demonstrated that coke deposition during CRE was mainly attributed to C2H4 cracking on the acidic sites of the catalysts, and thus coke deposition increased as acidic sites increased. An interesting observation is that the rate of C2H4 cracking was similar in the Ni doped support and the bare support, indicating that severe coke deposition of Ni/Al2O3 was caused by the C2H4 cracking over the support itself. Mg doped Al2O3 support was prepared to suppress the support acidity. Increasing Mg contents alleviated coke deposition and enhanced catalyst durability. Therefore, suppression of acidic sites of the supports will be an important factor in designing a stable catalyst for the high temperature CRE reaction.