Optimization of hydrogen purification from biomass‐derived syngas via water gas shift reaction integrated with vacuum pressure swing adsorption for energy storage

Abstract

Biomass is one of the promising sources to produce green H2, which can be considered an energy storage medium. To produce high‐purity H2 from biomass‐derived syngas, this study implemented a two‐stage H2 purification process. In the first stage, a water gas shift reaction (WGSR) was performed to enhance the H2 concentration in the syngas. The Taguchi method was employed to analyze the influence of the operating conditions and maximize the H2 concentration in the water gas shift reaction product. The results suggested that reaction temperature is a more dominant factor for enhancing the H2 concentration than the molar steam/carbon monoxide (S/CO) ratio. In the second stage, vacuum pressure swing adsorption was employed to obtain the high‐concentration H2 using the product from the water gas shift reaction having the optimum H2 concentration. Using the adsorption pressure as the primary parameter, it was found that high H2 purity and recovery could be obtained from vacuum pressure swing adsorption operated at low adsorption pressures. Based on this study's results, the vacuum pressure swing adsorption unit's best outcome occurs during an adsorption pressure of 2 kg·cm−2 and a flow rate of 17 L·min−1. Under these conditions, 93.61% H2 purity, 31.63% H2 recovery, 4.86 mol H2·(kgads·h)−1 productivity, and 448.14 kJ·(kg H2)−1 energy consumption are obtained.