Carbon Capture Using Porous Silica Materials.

As the primary greenhouse gas, CO emission has noticeably increased over the past decades resulting in global warming and climate change. Surprisingly, anthropogenic activities have increased atmospheric CO by 50% in less than 200 years, causing more frequent and severe rainfall, snowstorms, flash floods, droughts, heat waves, and rising sea levels in recent times. Hence, reducing the excess CO in the atmosphere is imperative to keep the global average temperature rise below 2 °C. Among many CO mitigation approaches, CO capture using porous materials is considered one of the most promising technologies. Porous solid materials such as carbons, silica, zeolites, hollow fibers, and alumina have been widely investigated in CO capture technologies. Interestingly, porous silica-based materials have recently emerged as excellent candidates for CO capture technologies due to their unique properties, including high surface area, pore volume, easy surface functionalization, excellent thermal, and mechanical stability, and low cost. Therefore, this review comprehensively covers major CO capture processes and their pros and cons, selecting a suitable sorbent, use of liquid amines, and highlights the recent progress of various porous silica materials, including amine-functionalized silica, their reaction mechanisms and synthesis processes. Moreover, CO adsorption capacities, gas selectivity, reusability, current challenges, and future directions of porous silica materials have also been discussed.