Zeolite and Silica-based CO2 Adsorbents

Abstract

The ever-increasing CO2 concentration in the atmosphere leading to global warming is one of the main problems that mankind has to face in the 21st century. To avoid the fact that sooner or later humanity will directly start to suffer from it, there is an urgent need to reduce the CO2 level by capturing it at the main sources of emissions such as coal-fired power plants and even better by trying to sequestrate it directly from air. Current post-combustion technologies based on strong chemical binding like scrubbing are barely reversible and therefore induce a high energy penalty. Physical binding by adsorption on nanostructured porous materials have become a smart alternative but a loss in selectivity, due to the presence of nitrogen, oxygen and water, has to be overcome. Zeolites and silicates, preferably modified by alkali cations, have been the focus of tremendous attention as low-temperature CO2 sorbents due to their high CO2 capture capacity, low regeneration temperature, relatively good stability and moderate cost. With the rapid development of these promising CO2 sorbent materials, a timely review is warranted. In this chapter, we critically summarize the performance of alkali-silicates, amine-grafted silicates, clays and zeolites. We hope this chapter can inspire and guide researchers from a wide range of backgrounds and help to pave the way for major breakthroughs in both fundamental and industrial studies in the field.