CO₂ 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 CO₂ capture applications, including direct air and point source capture. Various silica surface treatments and functionalization strategies are explored to enhance stability and CO₂ 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 CO₂ uptake compared to various SBA-15-based control supports are presented. The relationship between CO₂ diffusion and amine efficiency in these systems is explored using a previously reported kinetic model. The synthesized materials are characterized with CO₂ and H₂O isotherms, diffuse reflectance infrared Fourier transform spectroscopy, ¹H T₁-T₂ 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 CO₂ uptake are attributed to differences in the way the poly(ethyleneimine) interacts with the support surface.