Effect of air introduction on filamentous coke during CO2 reforming of tar with core-shell catalysts

• Published in: Journal of analytical and applied pyrolysis 2022-11, Vol.168, p.105765, Article 105765
• Main Authors: Tian, Yunlong, Ma, Xiaoqian, Chen, Xinfei
• Format: Article
• Language: English
• Subjects: Air; CO2 reforming tar; Coke deposition; Core-shell; Ni8Co/La2O3 @SiO2
• ISSN: 0165-2370; 1873-250X
• DOI: 10.1016/j.jaap.2022.105765

The coke accumulation is the main factor affecting the activity of nickel-based catalysts during the CO2 reforming of tar. In this work, toluene is chosen to study the influence of filamentous coke on the coke-forming mechanism of the Ni/La2O3 @SiO2 catalyst. Two methods are proposed to address the problem of reduced tar conversion of Ni/La2O3 @SiO2 due to coke deposition. The Ni/La2O3 @SiO2 is first modified with cobalt doping to improve the resistance to coke accumulation. The Ni8Co/La2O3 @SiO2 catalyst showed higher carbon conversion (50–75%) and hydrogen conversion (35–55%) than Ni/La2O3 @SiO2 within the 5 h tar reforming process. And the used Ni8Co/La2O3 @SiO2 catalysts had only 0.1 g/g of filamentous coke after reforming reaction. Next, air is introduced to oxidize the deposited coke to address the problem of coke accumulation affecting catalyst activity. An appropriate air flow rate could provide oxidation of the coke and prolong the reaction activity of the catalyst from 5 h to 10 h. [Display omitted] •Filamentous coke deposition is the main cause of catalyst activity reduction.•The cobalt doping can improve the resistance of coke deposition.•The introduction of air can oxidize the filamentous coke to prolong the catalytic activity.•The core-shell structure, H2 and CO can protect the Ni-Co alloy from oxidation.