Development of high temperature CO2 sorbents using solid wastes from power generation

One of various ways to curb anthropogenic carbon dioxide (CO2) emissions is by using Li4SiO4 sorbents to capture CO2, which have shown high CO2 uptake capacities (up to 367 mg CO2/g sorbent) at high temperatures (400 to 600 °C). In this study, solid wastes from coal- and biomass-fired boilers that contain high amounts (>47 wt%) of silica were used as precursors in the development of Li4SiO4-based high temperature CO2 sorbents via solid state (SS) and suspended impregnation (SI) methods. Thermogravimetric analyses (TGA) carried out in pure CO2 environment at sorption temperatures of 500 to 700 °C showed the waste-derived Li4SiO4 sorbents have high CO2 sorption capacities (up to 263 mg CO2/g sorbent at 700 °C). This study also experimented for the first time the potential of palm oil mill boiler ash (POMBA) as a waste-derived Li4SiO4 sorbent precursor. It was found that POMBA-derived sorbents showed high CO2 sorption capacities (up to 257 mg CO2/g sorbent at 700 °C in pure CO2 environment). These waste-derived Li4SiO4 sorbents exhibited CO2 sorption capacities exceeding some of those in published work (27 mg CO2/g sorbent). Furthermore, this study analysed the effect of excess lithium on waste-derived sorbents. It was found that depending on the materials used, the amount of excess lithium added during the preparation step affected CO2 sorption performance of the waste-derived sorbents