US Patent 8715617 Hydrogen production process with low CO

A hydrogen production process wherein steam and a hydrocarbon feed is reacted in a prereformer, the prereformed intermediate is further reacted in an oxygen-based reformer, the reformate is shifted and then separated by a pressure swing adsorber to form a H2 product stream and a tail gas, a first portion of the tail gas is recycled to the prereformer and/or the oxygen-based reformer, and a second portion of the tail gas is recycled to the pressure swing adsorber.