Germanium-incorporated lithium silicate composites as highly efficient low-temperature sorbents for CO2 capture

Abstract

Carbon dioxide emission from massive point sources such as industries and power plants is perceived to be a major contributor towards global warming and associated climate changes. Although lithium silicate has the highest capacity for CO₂ sorption (8 mmol g⁻¹), it is kinetically limited during the sorption process, particularly at temperatures below 500 °C. Herein, we report a facile strategy for the development of germanium-incorporated lithium silicate composites, which display enhanced CO₂ absorption capacity as well as kinetics in the temperature range of 150–680 °C. The absorption capacity of 324 mg g⁻¹ at the rate of 117 mg g⁻¹ min⁻¹ was measured at 680 °C, and 49 mg g⁻¹ at the rate of 36 mg g⁻¹ min⁻¹ was measured at 300 °C for samples with a Si : Ge molar ratio of 1 : 0.183. This study thus highlights the possibility of employing germanium-incorporated lithium silicates for the absorption of CO₂ at a wide range of temperatures, including the in situ removal of CO₂ from chemical and petrochemical reactions, such as the water–gas shift reaction occurring at low temperature ranges of 150–450 °C, that has hitherto been not possible with pure Li₄SiO₄.