CO Uptake and Stability Enhancement in Vinyltrimethoxysilane-Treated SBA-15 Solid Amine-Based Sorbents.

Silica-supported amine absorbents, including materials produced by tethering aminosilanes or infusion of poly(ethyleneimine), represent a promising class of materials for CO capture applications, including direct air and point source capture. Various silica surface treatments and functionalization strategies are explored to enhance stability and CO uptake in amine-based solid sorbent systems. Here, the synthesis and characterization of novel vinyltrimethoxysilane-treated Santa Barbara Amorphous-15 (SBA-15) supports and the corresponding enhancement in CO uptake compared to various SBA-15-based control supports are presented. The relationship between CO diffusion and amine efficiency in these systems is explored using a previously reported kinetic model. The synthesized materials are characterized with CO and HO isotherms, diffuse reflectance infrared Fourier transform spectroscopy, H T-T relaxation correlation NMR, and rapid thermal cycling experiments. The novel support materials are shown to enable high amine efficiencies, approaching a fourfold improvement over standard SBA-15-supported amines, while simultaneously exhibiting excellent stability when cycled rapidly under humid conditions. As the poly(ethyleneimine) loadings are held constant across the various samples, enhancements in CO uptake are attributed to differences in the way the poly(ethyleneimine) interacts with the support surface.