Novel Adsorption Process for Co-Production of Hydrogen and CO2 from a Multicomponent Stream-Part 2: Application to Steam Methane Reforming and Autothermal Reforming Gases

In this paper, we assess the performance of vacuum pressure swing adsorption (VPSA) for co-purification of H-2 and CO2 through modelling and process optimization. VPSA allows for the integration of two separation tasks, which can simplify the coupling of H(2 )production with carbon capture and storage (CCS). We assess the performance of five different VPSA cycles, four different feeds typical for steam methane reforming (SMR) and autothermal reforming (ATR) of natural gas or biomethane, and two different H-2 purity levels, that is, 99.9 and 99.97%. Three out of the five cycles can achieve the co-purification reaching CCS specifications for CO2 and even the higher H-2 purity level at a recovery above 90%. For ATR, argon as a trace impurity is difficult to separate, thereby limiting the attainable purity to 99.9%, but an argon-adjusted purity of over 99.97% can still be reached. The minimum electricity required for the separation is in the range of 300-500 kJ/kg CO2, with lower values for configurations with a low temperature water-gas shift reactor and for the lower H-2 purity level. This is well within the range of the exergy requirement of absorption-based pre-combustion CO2 capture processes, whilst reaching up to more than twice their productivity and integrating two separation units, that is, CO2 capture unit and H-2 purification unit, within a single one.