The kinetics of these reactions on a Ni/MgAl2O4 catalyst have been studied by Xu and
Froment [11]. The overall reactor operation requires that heat be provided to the reformer,
and this is done through combustion of methane (fuel) and PSA waste gas. Hydrogen is
produced together with all the other species and its conversion is further increased in the
water gas shift (WGS) reactor(s) where only the exothermic reaction (r2) is catalyzed at
temperatures lower than that of the reformer. Keiski et al. [12] studied the kinetics for the high
temperature water gas shift reaction on a Fe3O4-Cr2O3 catalyst for temperatures around 600
K and Rase [13] proposed a kinetic model for the low temperature water gas shift reaction on
a copper-zinc oxide catalyst for temperatures below 560 K. Most of the water is separated by
condensation as the gas stream is cooled down to almost ambient temperatures before
entering the pressure swing adsorption (PSA) unit where hydrogen can be purified to
99.999+% [14-15]. Species other than hydrogen are selectively adsorbed on a solid
adsorbent (e.g. activated carbon, 5A zeolite, [15]) at a relatively high pressure by contacting
the gas with the solid in a packed column in order to produce a hydrogen enriched gas
stream. The adsorbed species are then desorbed from the solid by lowering the pressure and
purging with high purity product hydrogen, and the PSA waste gas is in this way generated.
Continuous flow of product is maintained by using multiple, properly synchronized adsorption
beds. Combustion of the PSA waste gas and methane (fuel) is used to provide heat for the
reformer, and also for the preheating of feeds and the generation of export steam, as an
effort to recover the waste heat from the still-hot gases leaving the reformer, [2, 5-6].