Effect of the presence of water molecules on syngas combustion: A ReaxFF molecular dynamics study

Syngas (Synthesis Gas), a mixture of CO and H₂ gas, has a very high availability and great flexibility of usage. As such, syngas is expected to play a significant role in future energy generation. However, the varying amount of mixture components makes it difficult to develop a reliable reaction mechanism for syngas combustion. The main variable to consider for direct syngas combustion include the carbon monoxide/hydrogen ratio, fluctuating level of carbon dioxide and water and presence of other species that can significantly affect the combustion process. In this study, we investigate the effect of the presence of water molecules in syngas combustion. In our reactive molecular dynamics simulations, we consider two different carbon monoxide/hydrogen ratios and examine how water molecules, initially present in the system, affect carbon dioxide production at different temperatures. Our study indicates that a low amount of water molecules significantly increases carbon dioxide production, which is also observed experimentally. However, beyond that limit, water molecules have limited effect on CO oxidation. This latter effect is more prominent at higher temperatures. Overall, our simulations can be used as a computational inexpensive tool to predict optimal water levels for syngas combustion at any given condition.