Thermochemical performance assessment of solar continuous methane-driven ZnO reduction for co-production of pure zinc and hydrogen-rich syngas

Converting renewable solar energy to dispatchable chemical products via solar-driven thermochemical processes is one of the best solutions for long-term storage and fuel production. This study addresses performance assessment continuous methane-driven ZnO reduction, fully powered by heat, co-production hydrogen-rich syngas metallic Zn in a prototype consuming-bed reactor. On-sun experiments were conducted under CH4 co-feeding assess effect key parameters (inlet CH4/ZnO molar ratio: 1–1.5, temperature: 900–1000 °C, feeding rate: 0.5–1.5 g/min) order maximize yields, reactor metrics. As result, rise either ratio or temperature enhanced reaction extent but favored solid carbon formation, which downgraded quality, consumed more input. Increasing rate constant ZnO/CH4 significantly promoted + thanks both hastened consumption (boosting yield) reduced (improving conversion efficiency). However, excessively high caused temporal accumulation Optimal operating conditions on-sun reduction identified (at = 1.2 g/min, 1.5, 950 °C), yielding total yield 12.3 mmol/gZnO, formation down 0.58 63.0%, methane 10.6%, upgrade factor 1.08, solar-to-fuel efficiency 5.3%. High-purity particles with hexagonal morphologies generated mode, demonstrating proposed approach feasibility reliability simultaneous production single process.