Design and test of a miniature hydrogen production reactor integrated with heat supply, fuel vaporization, methanol-steam reforming and carbon monoxide removal unit

This study presents a designed and tested integrated miniature tubular quartz-made reactor for hydrogen (H2) production. This reactor is composed of two concentric tubes with an overall length of 60 mm and a diameter of 17 mm. The inner tube was designed as the combustor using Pt/Al2O3 as the catalyst. The gap between the inner and outer tubes is divided into three sections: a liquid methanol-water vaporizer, a methanol-steam reformer using RP-60 as the catalyst and a carbon monoxide (CO) methanator using Ru/Al2O3 as the catalyst. The experimental measurements indicated that this integrated reactor works properly as designed. The methanol conversion, hydrogen production rate and CO concentration were found to increase with an increasing methanol/air flow rate in the combustor and decreases with an increasing methanol/water feed rate to the reformer. The methanator experimental results indicated that the CO conversion and H2 consumption can be enhanced by increasing the Ru loading. It was also found that the CO methanation depends greatly on the reaction temperature. With a higher reaction temperature, the CO methanation, carbon dioxide (CO2) methanation, and reversed water gas shift reactions took place simultaneously. CO conversion was found to decrease while H2 consumption was found to increase. At a lower reaction temperature both the CO conversion and H2 consumption were found to increase indicating that only CO methanation took place. From the experimental results the maximum methanol conversion, hydrogen yield, and CO conversion achieved were 97%, 2.38, and 70%, respectively. The actual lowest CO concentration and maximum power density based on the reactor volume were 90 ppm and 0.8 kW/L, respectively.

► A miniature methanol-steam reformer with a carbon monoxide methanator is studied.
► The system also includes a combustor, a vaporizer and a CO2 removal unit.
► Reactor performance depends on methanol/water feed rate and methanol/air flow rate.
► Maximum CO conversion and methanol conversion achieved are 70% and 97%, respectively.
► Optimum system operating conditions are based on CO conversion and H2 consumption.