(7d) In-Pore Synthesis of Reactive Sites in Carbon Silica Composites for Gas-Phase Adsorption of Toxic Industrial Chemicals

Adsorbent technology is critical in maintaining breathable air environments for diverse civilian and military applications. Gas masks for military personnel and first responders are examples of such technologies used to capture toxic industrial chemicals (TICs) from air. Our approach involves the synthesis of composite adsorbents with various phases each capable of targeting a variety of adsorbates. This contribution describes the development of carbon-silica composites (CSCs) containing reactive sites created via in-pore reactions. These sites provide targeted removal capabilities for basic and acid-forming TICs such as ammonia and sulfur dioxide. Breakthrough experiments are conducted on synthesized materials using NH₃ (1500 ppm) and SO₂ (500 ppm) to determine their adsorption capacities. Adsorbents are also characterized by porosimetry, crystallography, and microscopy techniques.

The base composite material consists of a nonpolar carbon phase and a polar silaceous phase made from polymerizing furfuryl alcohol within the pores of MCM-41 to form the microporous structure of the CSC. The composite is further functionalized by introducing various metal salts as reactive sites for redox reactions to enhance the removal capacities for TICs. A unique advantage of this functionalization is the capability of performing precipitation reactions between combinations of chemical moieties within the pores of the substrate. The mechanism of in-pore synthesis of otherwise non-soluble functionalities incorporated into well-defined porous adsorbent structures may be appealing for many catalysis and separation processes.