SrO is normally regarded as infeasible for CO2 capture due to the requirement of high temperature for regeneration. Using CeO2 to modify SrO to enhance CO2 capture was reported and applied for ICCU-DMR (dry methane reforming). CeO2 was involved in the regeneration of Sr-based sorbent. At the stage of CO2 capture from flue gas, the oxygen storage capacity of CeO2 could be enhanced. The enhancement of SrO sorbent stability using CeO2 is shown below:
“TGA profiles of 35 carbonation/decarbonation cycles at 875 °C with 20% CO2 and 20% H2 using (a) SrNi and (b) SrCe0.5Ni0.5.” 10.1039/D1TA09967A
The following methods were used for the ICCU experiments:
“The experiments were conducted in a U-tube with 0.5 g material in each test. While conducting SLDRM with residual O2-containing flue gas, the sample was periodically exposed to 25 vol% flue gas (3 vol% O2, 15 vol% CO2 and 82 vol% Ar) in Ar during the carbonation stage and 10 vol% CH4 in Ar during the reforming stage. The flow rate in the carbonation stage is flue gas/Ar = 10/30 sccm. And the flow rate in the reforming stage is CH4/Ar = 3.3/30 sccm. 2 min Ar of 30 sccm was used for purging between each stage. ”
The work reported 91% CH4 conversion and >72% CO2 capture efficiency over 30 cycles of ICCU. However, the capacity of CO2 capture and the conversion of CO2 were not included. The other challenge of using SrO2/CeO2 based DFMs is that the materials require a very high working temperature (~850 °C). It was clear that during the CO2 capture stage, coke was oxidised, forming CO. This could be a potential problem if CO2 sources are flue gas, because the formed CO is a new pollutant.
Above figure – (a) A typical gas product distribution using SrCe0.5Ni0.5 under CH4-flue gas cycles at 875 °C, and dashed lines are the blank gas flow at room temperature with no sorbents in the reactor; (b) stability of SrCe0.5Ni0.5 under 20 CH4-flue gas cycles at 875 °C. 10.1039/D1TA09967A