Modelling methane and ethane photolysis in waste gas: Optimization of reaction networks

Abstract

A mechanistic model for the ultraviolet degradation of methane and ethane in waste gas was developed with the focus on reaction network development and optimization. The research serves a dual purpose of removing natural gas condensate emissions, and converting condensates to added-value products. A comprehensive reaction network including all possible reactions was developed, and kinetic constants were taken from the literature or estimated based on analogues. Overall, 162 reactions were included for the most complete case. Next, the model was screened for reactions that did not affect the simulation results. As complexity increases, it was shown that the model devotes an increasing fraction of time calculating reactions that are negligible in the overall process. Based on the simulation results it is expected that the model can be extended to higher alkanes with a reasonable run-time in addition to keeping precise simulation results. The model predicts that high ethane conversion is possible while maintaining low methane conversion, and it is expected that this effect will be even more pronounced in the presence of higher alkanes. Overall, the projected model can be used to establish the feasibility of converting natural gas condensates to value-added products without degrading its main content, methane; provided that oxygen and water vapour are available for the oxidation.