This invention discloses an optimum set of adsorbents for use in
H.sub.2-PSA processes. Each adsorbent bed is divided into four regions;
Region 1 contains adsorbent for removing water; Region 2 contains a
mixture of strong and weak adsorbents to remove bulk impurities like
CO.sub.2; Region 3 contains a high bulk density (>38
lb.sub.m/ft.sup.3) adsorbent to remove remaining CO.sub.2; and most of
CH.sub.4 and CO present in H.sub.2 containing feed mixtures; and Region 4
contains adsorbent having high Henry's law constants for the final
cleanup of N.sub.2 and residual impurities to produce hydrogen at the
desired high purity.