Nitrogen fixation in plasma integrated mixed ionic electronic conducting membrane reactors

Nitric acid (HNO3) is a key industrial chemical, traditionally produced through the Ostwald process, which relies on ammonia (NH3) derived from the fossil-based Haber–Bosch process. This conventional route is highly energy and carbon-intensive and unsuitable for decentralized or small-scale applications. Since nitric oxide (NO) is the central intermediate in HNO3 production, developing alternative electrified pathways for direct NO synthesis - bypassing NH3 - is of growing interest. Here, we present a plasma-enabled mixed ionic–electronic conductor (MIEC) hollow fiber reactor that simultaneously separates oxygen from air and fixes nitrogen into NO in a single step. The design employs Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) membranes operated at 600 °C under a pressure gradient to achieve oxygen separation efficiencies of up to 98%. In the permeate zone, Radio-frequency (RF) plasma activation generates reactive nitrogen species that react with transported oxygen ions to form NO at rates up to 0.22 micro mol s-1. The observed NO concentrations exceed thermal equilibrium by more than two orders of magnitude, demonstrating the critical role of plasma quenching. Multi-fiber configurations enhance both efficiency and scalability, with extrapolated designs predicted to boost performance. This concept establishes a direct, electrified air-to-NO pathway, offering a sustainable alternative to conventional nitric acid production.