Using a water-shift reaction, the syngas can be chemically shifted; the resulting hydrogen and CO2 can be separated using physical sorbents (e.g., the Selexol process).
Proton chemical shifts were referenced to a temperature-dependent water shift (eq 1 ), where T is temperature in kelvin measured at pH 5.5.
This occurs in a water gas shift (WGS) reactor where the CO2/H2 gas mixtures can be separated into the individual components.
The goal of this work is to understand the effect of the relative values of membrane permselectivity, permeation flux and reaction rate on the performance of a water gas shift membrane reactor.
The implications of this work suggest that a water gas shift reactor for a fuel processor (and other applications) will approach sizes one-to-two orders of magnitude smaller than conventional processing hardware.
During the hydrogen recovery process, the anode exhaust gas (37.1% H2O, 45.9% CO2, 5.7% CO, and 11.2% H2) is sent through a water gas shift (WGS) reactor to increase the hydrogen and carbon dioxide composition, and then water is removed in a vapor liquid separator.
Based on the optimized reformer, a fuel processor comprised of an ATR unit, a water gas shift (WGS) unit, a CO preferential oxidation (PROX) unit and a fuel evaporator unit has been developed and successfully integrated with a 75 kWe class PEMFC stack.
Two possibilities of coupling a membrane with a water gas shift reactor (WGSR) are investigated: either as an open architecture, where hydrogen separation modules are located before and/or after the WGSR, or as an integral WGSR membrane reactor (closed architecture), where reaction and separation occur in a single step.
The process is modeled as a mixed-integer non linear programming problem (MINLP) for a superstructure embedding two different gasification technologies, direct and indirect, and two reforming modes, partial oxidation or steam reforming, gas cleaning and a water gas shift reactor (WGSR) with membrane separation is used to obtain pure hydrogen.
The results show that for LT-PEMFCs, the optimal temperature and steam to glycerol molar ratio of the glycerol reforming process (consisting of a steam reformer and a water gas shift reactor) are 1000 K and 6, respectively; under these conditions, the maximum hydrogen yield was obtained.
It was observed that the conjugate conformation changes are the result of water shifting from a thermodynamically favorable solvent to an unfavorable one, a process that then leads to compaction of the conjugate.
