US EPA

4235925 

Journal Article 

15
N Solid State NMR Spectroscopic Study of Surface Amine Groups for Carbon Capture: 3-Aminopropylsilyl Grafted to SBA-15 Mesoporous Silica 

Shimon, D; Chen, CH; Lee, JJ; Didas, SA; Sievers, C; Jones, CW; Hayes, SE 

2018 

1 

Environmental Science & Technology
ISSN: 0013-936X
EISSN: 1520-5851 

American Chemical Society 

52 

3 

1488-1495 

English 

29257887 

10.1021/acs.est.7b04555 

WOS:000424851700063 

Materials composed of high-porosity solid supports, such as SBA-15, containing amine-bearing moieties inside the pores, such as 3-aminopropylsilane (APS), are envisioned for carbon dioxide capture; solid-state15N NMR can be highly informative for studying chemisorption reactions. Two15N-enriched samples with different APS loadings were studied to probe the identity of the pendant molecules and structure of the chemisorbed CO2species.15N cross-polarization magic-angle spinning NMR provides unique information about the amines, whether they are rigid or dynamic, by measuring contact time curves and rotating frame, T1ρ(15N), relaxation. Both carbamate and carbamic acid are formed; carbamic acid is shown to be less stable than carbamate. After desorption, a steady state for the chemisorbed reaction product is reached, leaving behind carbamate.15N NMR monitors the evolution of the species over time. During desorption, APS is regenerated, but the ammonium propylsilane intensity does not change, leading us to conclude that carbamic acid desorbs, while carbamate (to which ammonium propylsilane is ion paired) persists. A secondary ditehtered amine present does not react with CO2, and we posit this may be due to its rigidity. These findings demonstrate the versatility of solid-state NMR to provide information about these complex CO2reactions with solid amine sorbents. 

Ammonium persulfate; Carbon capture; Carbon dioxide; Chemisorption; Desorption; Light polarization; Magic angle spinning; Nuclear magnetic resonance spectroscopy; Organic acids; Silica; Spectroscopic analysis; Carbon dioxide capture; Cross polarization magic-angle spinnings; Mesoporous Silica; Rotating frame; Solid amine sorbents; Solid state NMR; Solid supports; Spectroscopic studies; Solid state reactions; 3 aminopropylsilane; amine; ammonia; carbamic acid; carbon; carbon dioxide; mesoporous silica nanoparticle; silane derivative; sorbent; unclassified drug; amine; SBA-15; silicon dioxide; carbamate (ester); carbon; carbon dioxide; chemical reaction; desorption; nitrogen isotope; nuclear magnetic resonance; organic acid; organic nitrogen compound; polarization; silica; adsorption; Article; chemical reaction; chemical structure; desorption; nitrogen nuclear magnetic resonance; polarization; porosity; quantitative analysis; solid state; surface property; Adsorption; Amines; Carbon; Carbon Dioxide; Silicon Dioxide