Experimental studies on hydrogen production from steam reforming of methanol integrated with metal hydride-based hydrogen purification system

The present study reports the feasibility of a metal hydride (MH) purification technology employed for hydrogen produced via SRM using Cu/ZnO/Al2O3 catalysts. The catalysts were synthesized by using the coprecipitation method and characterized by various techniques such as XRD, BET, FESEM, FETEM, EDX, XPS, TGA, FTIR, TPR and N2O chemiosorption. SRM was carried out under varying operating conditions viz., temperature 200-320 degrees C, water to methanol molar ratio (W/M) 1-1.7, and a feed flow rate (F-M/W) 2.78-27.78 mmol center dot min(-1)g(-1). Increasing the reaction temperature raised the methanol conversion rate, reaching 100 % at 300 degrees C, but it simultaneously promoted the formation of CO via rWGS. The increase in W/M ratio increases the methanol conversion rate while reducing the CO selectivity. The impact of feed flow rate (F-CH3OH/W-cat) on conversion and selectivity revealed that both methanol conversion and CO selectivity decreased at higher feed flow rates, but the rate of hydrogen production increased significantly. Specifically, raising F-CH3OH/W-cat from 2.78 to 27.8 mmol center dot min(-1)g(-1) led to a decline of methanol conversion from 97% to 30% and CO selectivity from 0.8 % to 0 %, but the hydrogen production rate was increased from 180 to 570 mL min(-1)g(-1) at 280 degrees C. The integration of MH based purification system to the production line resulted in the production of highly pure hydrogen (nearly 99% purity) using low-grade heat input (50-60 degrees C), for an impurity range of up to 40%.