Solid Sorbents for Removal of Carbon Dioxide from Gas Streams at Low Temperatures

Although fossil fuels provide more than 98 percent of the world’s energy requirements, their combustion results in a major source of the greenhouse gas CO₂. The ability to efficiently and safely absorb CO₂ then becomes very important to the development and application of cost-effective technologies for the removal of CO₂ from gas streams. As a result, the U.S. Department of Energy has placed a high priority on research that reduces the high costs related to CO₂ separation and capture processes.

Currently used absorption processes, often referred to as wet chemical stripping, use aqueous amine solutions to facilitate the removal of CO₂ from gas streams in some industrial applications. However, CO₂ capture and sorbent regeneration using this method requires high temperatures and is therefore energy-intensive. Furthermore, the amine solution has a limited lifetime due to degradation through oxidation and subsequently causes corrosion problems. Although solid sorbents serve as alternatives to wet chemical stripping, they are limited by their respective surface areas. Since only the surface is involved in the reaction, a very limited quantity of reactive material can be incorporated in the solid sorbent.

This patented technology addresses the limitations of the previous absorbent process by producing a new sorbent with capabilities that depend on total volumes rather than just surface areas. In addition, the new sorbent can be easily regenerated at moderate temperatures (70-100°C), and the material used to produce the sorbent is expected to be inexpensive. Furthermore, the new sorbent will eliminate corrosion and evaporation problems that plagued the previous sorption process.