Description
Nitrogen fixation (NF) and CO2 conversion are critical processes for sustaining global food production and mitigating climate change. Conventional nitrogen fertilizer production relies heavily on the energy-intensive Haber–Bosch process, which consumes 1–2% of global energy and emits over 300 million tons of CO2 annually, while remaining unsuitable for decentralized applications. Plasma-based approaches offer a promising alternative by enabling nitrogen activation and CO2 reutilization under mild conditions.
In this work, a magnetic field stabilized glow discharge (MSGD) device is employed to for atmospheric-pressure NF and CO2 conversion using N2-CO2 and air-CO2 gas mixtures. The device employs an external magnetic field to stabilize the plasma, allowing all gases to be processed effectively as they flow through the plasma zone under the influence of gas flow and Lorentz forces. It is found that for N2‐CO2 and air‐CO2 gas mixtures, the CO concentration increases with the CO2 volume fraction, reaching a maximum of 56 198 ppm at 100% CO2, and the corresponding energy cost for CO2 conversion is the lowest at 0.61 MJ/mol, while the energy efficiency of CO2 conversion reaches its highest at 46.7%.
For N2‐CO2 discharge, the lowest energy cost for NF (11.24 MJ/mol) occurs at a gas ratio of approximately 1:1 (N2: CO2), with a NOx concentration of 2968 ppm. For air‐CO2 discharge, the lowest NF energy cost (2.59 MJ/mol) is achieved with pure air, resulting in a NOx concentration of 12 103 ppm. As the CO2 volume fraction increases, the NOx concentration decreases while NF energy cost rises. In both discharge scenarios, the overall energy efficiency for combined NF and CO2 conversion increases with the CO2 volume fraction.
Plasma diagnostics indicate a reduced electric field of approximately 49.6 Td, under which about 90% of electron energy is channeled into vibrational excitation of N2 and CO2. As a result, NO formation is dominated by the vibrationally enhanced Zeldovich mechanism, whereas CO is primarily produced through vibrational dissociation of CO2. These results demonstrate the potential of MSGD plasma for efficient, flexible, and low-carbon NF and CO2 conversion.