Kinetics and mechanism of catalytic carbon gasification

• Published in: Fuel (Guildford) 2016-11, Vol.183, p.457-469
• Main Authors: Lobo, Luís Sousa, Carabineiro, Sónia A.C.
• Format: Article
• Language: English
• Subjects: Carbon; Catalysis; Gasification; Kinetics; Mechanism; Nanoparticles
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2016.06.115

•The behavior of catalyst nanoparticles in catalytic carbon gasification is reviewed.•Evidence of the carbon bulk diffusion mechanism operating is summarized.•Linking kinetics with in-situ HRTEM and XRD studies allows a better understanding. The evidence of the carbon bulk diffusion mechanism, operating in catalytic carbon gasification, is summarized. Linking visual and structural observations (transmission electron microscopy and X-ray diffraction) with comprehensive kinetic studies offers a good basis to understand the details of the phenomenological behavior. The role of the catalyst nanoparticles in catalytic coal/coke gasification and in graphene reactions is briefly reviewed. Knowledge of the solid-state phases operating under steady-state reaction and of the “sintering like” catalyst-carbon contact is essential to understand the most likely reaction sequence: 1st step - carbon dissolution; 2nd step - C bulk diffusion; 3rd step - surface reaction of emerging C atoms with the reactant gas. Kinetics and preliminary solid-state changes observed in graphite gasification and in coke/coal gasification leads to the conclusion that they follow the same mechanism. Using an analogy with proton exchange membranes in fuel cells: catalytic carbon gasification is promoted by carbon exchange moving nanoparticles. A better understanding of the mechanism may lead to improvements in industrial processes.