Silica Gel Supported Solid Amine Sorbent for CO2 Capture

Point source CO2 capture (PSCC) is a key technology to decarbonize various industries and direct air capture (DAC) is a potential technology to remove CO2 from the air. The chemical adsorption process using solid amine sorbents can be used for both PSCC and DAC. Solid amine sorbents have potential advantages as compared to the liquid amine sorbents. Solid amines can perform cyclic adsorption-desorption at a much lower energy than liquid amine such as alkanol amines. Environmental concerns related to monoethanolamine (MEA) can be eliminated by designing and upscaling solid amine sorbents. In the past few years, research groups worldwide have been involved in developing and designing cost-effective solid amine sorbents. However, most of them still need to be demonstrated for industrial applications. One of the potential support materials is silica gel which is commercially available and attractive as a low-cost support material for designing silica-based solid amine sorbents for large-scale CO2 capture applications. Different impregnation methods such as physical adsorption and covalent functionalization of silica surface have been used to attach amines and discussed. In this review, a comprehensive critical analysis of commercially available silica gel-supported solid amines is carried out. Silica gel-based solid amine sorbents are discussed and reviewed for desired factors such as adsorption capacity, adsorption and desorption conditions, and kinetics involved in these processes. Finally, a few recommendations are proposed for further development of low-cost, lower carbon footprint solid amine sorbents for large-scale deployment of CO2 capture technology.