Defective graphitic carbon as a high chlorine conversion catalyst for methyl chloride production from methane

In the methane chlorination reaction, unreacted Cl2 isa cause of reactor corrosion and contamination, and thus research on catalysts with high Cl2 conversion is needed. In this study, carbon-based catalysts were used for the methane chlorination reaction. As carbon-based catalysts, commercially available amor-phous carbons with sp3-dominant hybridized structures and graphitic carbons with sp2-dominant hybri-dized structures were investigated. Two different groups of carbons exhibited distinct catalytic performance in CH4 and Cl2 conversions and product selectivity. Amorphous carbons exhibited relatively low CH4 and Cl2 conversions, and an undesired product, CCl4, was largely generated. On the other hand, graphitic carbons exhibited relatively high conversions and CCl4 was not generated. In particular, a gra-phitic carbon with an optimum defect site exhibited almost 100% Cl2 conversion. These catalysts can be strongly affected by the adsorption phenomenon of the reactants and products. We propose reasons for the different catalytic performance and plausible reaction mechanisms for the carbon-based catalysts and verify them through experimental analyses: Raman spectroscopy, TGA-MS, XPS, XRD, and EDS and den-sity functional theory (DFT) calculations.(c) 2023 The Author(s). Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry. This is an open access article under the CC BY-NC-ND license (http://creativecom-mons.org/licenses/by-nc-nd/4.0/).

Automated summary

In the methane chlorination reaction, carbon-based catalysts exhibited different catalytic performances and selectivities. Amorphous carbons showed lower conversions and the generation of undesired product CCl4, while graphitic carbons showed higher conversions and no generation of CCl4. The presence of an optimum defect site in graphitic carbon led to almost 100% Cl2 conversion. The different catalytic performances can be attributed to the adsorption phenomenon of reactants and products.