Autothermal Reforming of Methane on Rhodium Catalysts: Microkinetic Analysis for Model Reduction

TL;DR

This paper develops a simplified yet accurate microkinetic model for methane autothermal reforming on rhodium catalysts, reducing complexity by 33% while maintaining predictive accuracy across various conditions.

Contribution

It introduces a hierarchically reduced rate expression derived from detailed mechanisms without prior assumptions, validated against experimental data.

Findings

33% reduction in microkinetic mechanism complexity

Accurate prediction of conversions and outlet compositions

Identification of key rate-determining steps

Abstract

Methane autothermal reforming has been studied using comprehensive, detailed microkinetic mechanisms, and a hierarchically reduced rate expression has been derived without apriori assumptions. The microkinetic mechanism is adapted from literature and has been validated with reported experimental results. Rate Determining Steps are elicited by reaction path analysis, partial equilibrium analysis and sensitivity analysis. Results show that methane activation occurs via dissociative adsorption to pyrolysis, while oxidation of the carbon occurs by O(s). Further, the mechanism is reduced through information obtained from the reaction path analysis, which is further substantiated by principal component analysis. A 33% reduction from the full microkinetic mechanism is obtained. One-step rate equation is further derived from the reduced microkinetic mechanism. The results show that the this rate equation accurately predicts conversions as well as outlet mole fraction for a wide range of inlet compositions.