(158h) Lithium Silicates for High Temperature CO2 Capture

Hydrogen is produced from natural gas (or biomass) by the two-step steam methane reforming (SMR) and the water-gas shift (WGS) reactions This is an ideal opportunity for sorption-enhanced reaction, in which CO₂ is chemically fixed to a suitable substrate, thus driving the equilibrium in the WGS shift step to the right. Lithium-based ceramics, notably Li₄SiO_4, have been evaluated as potential CO₂ sorbents fo r this purpose. However, these are bulk-phase materials, once the reaction products cover the surface, adsorption stops. Our approach to improving reversible CO₂ sorption is to create a surface lithium-silicate structure on a mesoporous silicate such as SBA-15 or similar materials. Modification of the lithium silicate composition will influence the thermodynamics enabling us to tune the performance of these materials for reversible, high-temperature adsorption of CO₂. This talk will review our efforts to develop these materials by direct sol-gel methods, and by atomic layer deposition or incipient wetness of suitable lithium precursors onto mesoporous silicates.