Separation of hydrogen from 10 % hydrogen plus methane mixtures using double-stage Vacuum Swing Adsorption (VSA)

Transportation of hydrogen by blending it into the existing natural gas infrastructure is one economical way of having a green future. After co -transportation of hydrogen this way, hydrogen deblending from natural gas is needed at various locations for different end -users. The hydrogen content in pipelines at the primary injection phase will be low ( <20 %) which makes the separation challenging. The goal of the current study is to investigate the extraction of high purity hydrogen from a 10 % hydrogen + natural gas mixture using Vacuum Swing Adsorption (VSA). A four -bed VSA plant using activated carbon was used to conduct the experiments in our lab using a binary mixture of 10 % H- 2 + CH (4 )(% mol/mol). High purity hydrogen (99 %) was achieved at 102 kPa feed pressure. After validation of our simulation tool with experimental results, Aspen Adsorption software was used to assess the performance of producing 99 % hydrogen purity using a double -stage VSA process at small scale. Results revealed that achieving high -purity hydrogen using a double -stage VSA, by upgrading H 2 from 10 % to 50 % in the first stage and then to 99 % H 2 in the second stage leads to better separation performance and less energy consumption than a single stage VSA for the same separation target. Afterwards, a five -bed double VSA system at industrial scale was simulated using Aspen Adsorption, to produce high hydrogen purity from a representative 10 % hydrogen + natural gas mixture. High purity hydrogen ( >99 %) along with high recovery ( >82 %) were achieved at a feed pressure of 110 kPa.