Study of sour water gas shift using hydrotalcite based sorbents

One of the most promising alternatives to the use of liquid amines and pressure swing adsorwption (PSA) for H2 production and CO2 capture in pre-combustion processes is the so called sorption-enhanced water gas shift reaction concept (SEWGS). This study presents the performance in SEWGS of two sorbents, a K-promoted hydrotalcite with Mg/Al ratio = 2, which based on our previous work was selected as the most promising CO2 capture sorbent tested under sweet water gas shift (WGS) operating conditions, and a bi-functional material prepared by impregnation of the K-promoted hydrotalcite with Co and Mo in order to enhance the catalytic properties of the material.Short term sour CO2 capture tests and WGS tests at similar operating conditions (T = 300-350 °C; P = 15 bar) were carried out in order to study the effect of the presence of H2S in the feed gas stream in the CO2 capture capacity and catalytic activity of both sorbent materials as well as to compare their performance in developed tests. Finally, the feasibility of using the bifunctional material for sour SEWGS processes was also studied.Impregnation with Co-Mo did not adversely affect the adsorption capacity of the K-promoted hydrotalcite and enhanced catalytic activity, allowing total CO conversion even after adsorption capacity had been reached.