Unveiling the thermodynamic landscape of N 2 -assisted CO 2 utilization for dry reforming of methane

Greenhouse gas (GHG) emissions, mainly CO2 and CH4, are a major environmental issue due to the strong dependence on fossil fuels. At the same time, these gases can be used as valuable feedstocks. Dry reforming of methane (DRM) converts CO2 and CH4 into useful syngas using high-temperature plasma technology. However, the thermodynamic role of nitrogen (N2) in this process is still not well understood. In this work, a detailed thermodynamic analysis of N2-assisted DRM is performed for high-temperature plasma systems. The study is based on Gibbs free energy minimization, along with the element potential method to calculate equilibrium constants. The equilibrium composition of syngas and coke formation is examined over a wide range of temperatures and pressures. Syngas production is strongly endothermic and becomes more favorable at high temperatures. At these conditions, coke formation is also reduced. When N2 is added, N2 fixation can occur at the same time. Ammonia (NH3) is favored at lower temperatures below 1000 K, while nitric oxide (NO) is favored at temperatures above 2000 K. Pressure affects the system in two ways. Higher pressure lowers CH4 and CO2 conversions at lower temperatures, while improving N2 conversion at high temperatures. Overall, the results show that CO2, CH4, and N2 can be used together in one plasma system. This study provides useful guidance for adjusting operating conditions to produce either syngas or N2-based chemicals and supports the future industrial use of plasma technology for greenhouse gases (GHGs) utilization.