Sensitivity analysis and uncertainty quantification of chemical kinetic parameters in methane pyrolysis

Ethylene (C2H4) is a widely used feedstock of the chemical industry. Its production is estimated to account for about 1% of yearly global greenhouse gas emissions. Plasma pyrolysis has been proposed as a means to convert methane into higher-value hydrocarbons, such as ethylene and acetylene (C2H2). Many studies have focused on the chemical kinetic pathways for specific plasma conditions. However, there is still no overall description of the chemical pathways responsible for the conversion between methane, C2 carbons and other higher hydrocarbons. Moreover, the chemical kinetic models used in these studies are imported from combustion mechanisms. These are optimized to reproduce an ensemble of experimental combustion conditions which, by definition, contain oxygen in their mixtures. An assessment of chemical reaction pathways and uncertainties of these mechanisms are warranted to prove the suitability of these mechanisms for plasma pyrolysis purposes. In this work, the parameters of a chemical model for methane pyrolysis are analyzed through a sensitivity analysis and uncertainty quantification. With these analyses, key reactions have been identified for the conversion of methane and formation of products. The uncertainties of parameters of the reaction rate constants are found to have negligible impact on the overall uncertainty of chemical products.