Abstract
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.