Optimized hydrogen purification for fuel cell quality from quinary coke oven gas via layered pressure swing adsorption under non-isothermal conditions

Coke oven gas from steel industries offers a valuable hydrogen rich fuel but is accompanied by impurities, such as CH4 and CO2, that contribute to the environmental footprint. The process of extracting H2 from coke oven gas not only provides clean energy from the alternative source, but also prevents the release of these impurities. Motivated by the promising H2 source alternative, a 2-bed, 6-step pressure swing adsorption system operating under non-isothermal conditions was used to purify H2 from coke oven gas. A validated multi-component adsorption model was developed via Aspen Adsorption to simulate and optimize the process. The validated model revealed strong correlations between the factors (adsorption pressure, adsorption temperature, adsorption time, and H2 concentration) and responses (purity and recovery of H2). The findings indicated that increasing the H2 feed concentration resulted in an improvement in H2 purity but a decline in recovery. Conversely, an extended duration of adsorption exhibited an adverse influence on both the purity and recovery of H2. Furthermore, the study indicates that higher adsorption pressure and temperature were correlated with lower H2 purity but improved recovery performance. To optimize the pressure swing adsorption process, the desirability function was applied within the response surface methodology model, enabling the determination of optimal conditions for the purification process. The optimized H2 purity and recovery were found to be 99.995% and 62.758%, respectively, at H2 feed concentration of 49%, adsorption time of 160 s, pressure of 6 atm, and adsorption temperature of 293 K.