Hydrotalcite as CO2 sorbent for sorption-enhanced steam reforming of methane

Sorption-enhanced reforming of methane is an attractive option for the combined production of electricity and capture of CO2, In this process, the steam-reforming catalyst is mixed with a CO2 sorbent. During the reaction, CO2 is adsorbed, leading to an increase of the hydrogen production rate. Once the sorbent is saturated, it must be regenerated using purge gas, usually steam. The amount of steam needed for CO2 removal from the saturated sorbent determines the system efficiency of the process to a large extent. In this paper, several potassium-promoted hydrotalcite samples, both obtained commercially and prepared in-house, are tested for their suitability as a CO2 sorbent for sorption-enhanced reforming of methane. In particular, the purge gas to adsorbed CO2 ratio is determined under various operation conditions. It is shown that this ratio is still too large under the investigated conditions. Mixed with steam-reforming catalyst the hydrotalcite sorbent can adsorb sufficient CO2 to enhance the CH4 conversion to almost 100%.