Experimental Evaluation of Two- and Four-Bed PSA Cycles for Hydrogen Recovery from Syngas and Water–Gas Shift Syngas

This study experimentally evaluates hydrogen recovery from synthetic syngas and water–gas shift (WGS) syngas using a laboratory-scale pressure swing adsorption (PSA) unit equipped with layered activated carbon/zeolite 5A beds. Breakthrough tests were first performed to determine adsorption-time limits and identify the critical impurity controlling product quality. Continuous PSA experiments were then carried out using two cycle configurations: a two-bed Berlin-type cycle and a four-bed Linde-type cycle. CO was the first impurity breakthrough experimentally detected and it therefore defined the practical adsorption-time cut-off, whereas CO2 exhibited the strongest retention, especially in beds with an increased activated-carbon fraction. The results showed a clear trade-off between purity and recovery. The four-bed Linde-type cycle provided a wider operating window than the two-bed Berlin-type cycle, owing to pressure equalization and product-purge steps. The best overall performance was obtained for WGS syngas with the 1.6:1 AC: zeolite bed, reaching 99.5 vol.% H2 at 84% recovery and maintaining 99.2 vol.% H2 at 86% recovery. The tail gas was enriched in CO2 up to approximately 72 vol.%, indicating potential for integration with downstream CO2 management.