Experimental studies on hydrogen production from methanol steam reforming under wide liquid feed rates

Methanol steam reforming for hydrogen production (MSR) is regarded as an ideal hydrogen production process due to its excellent reaction performance. However, most existing studies focus on microreactor design and the optimization of narrow liquid feed rates, with insufficient research on scale-up constraints in large-scale applications and oversimplified evaluation systems, which hinders the industrialization process. This study constructed a vertical reactor (inner diameter: 72 mm, length: 2 m) integrated with axial-circumferential thermocouple arrays. The effects of operating parameters on hydrogen production efficiency, the transient distribution of the reactor's internal temperature field and the variation laws of steady-state parameters under wide liquid feed rate (Q) ranges were investigated. Experimental results show that temperature drives the enhancement of methanol conversion, while it requires dynamic matching with the water-to-methanol ratio (S/C) to suppress the increase in CO selectivity. Moderate liquid feed rate achieves the synergy between mass transfer enhancement and residence time optimization. The optimal reaction conditions are 250 °C, S/C = 1.4, and 45 mL/min, under which the methanol conversion rate is 86.71%, the energy conversion efficiency is 67.30%, and the axial temperature gradient equilibration time is 23.75 min. In addition, based on the experimental results, this study established a reaction kinetic prediction model for hydrogen production rate under wide liquid feed rate ranges, providing theoretical support for overcoming the scale-up constraints of MSR and promoting its industrial application.