Functionalization of carbon silica composites with active metal sites for NH3 and SO2 adsorption

•Carbon silica composites (CSCs) and MCM-41 are functionalized with metal salts via incipient wetness.•Functionalization with metal salts enhances NH3 and SO2 capacities of CSCs and MCM-41.•Among the salts tested, ZnCl2 is most effective for NH3 and K2CO3 is most effective for SO2.•At 30 wt% metal salt, Cu(NO3)2-CSC provides high capacities for both NH3 and SO2.

A highly porous adsorbent capable of broad spectrum filtration of toxic industrial chemicals is necessary for many civilian and military applications. A carbon-silica composite material previously developed in our lab consists of two unique phases used to target low concentrations of NH3 and SO2, representative of basic and acid-forming gases. In this work, it is shown that the adsorption performance of this base CSC material can be further enhanced by functionalization with reactive metal sites. Several water-soluble metal salts at various concentrations are added to the CSC material as well as to MCM-41 via incipient wetness. Along with capacity measurements, the incorporation of metal salts on CSCs and MCM-41 is studied using crystallinity, microscopy, and porosity characterization techniques. Results show that successful, well-dispersed functionalization of metals on CSCs is possible while maintaining structural integrity. Capacity measurements show that ZnCl2-CSC is the most effective material for NH3 adsorption, while K2CO3-CSC is most effective for SO2 adsorption. In order to efficiently target both adsorbates with one material, [30 wt% Cu(NO3)2]-CSC is identified as the best compromise, with NH3 and SO2 capacities of 4.0 and 0.45 mol/kg, respectively.

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