Effect of Amine Surface Coverage on the Co-Adsorption of CO<sub>2</sub> and Water: Spectral Deconvolution of Adsorbed Species

Didas, Stephanie A.; Sakwa-Novak, Miles A.; Foo, Guo Shiou; Sievers, Carsten; Jones, Christopher W.

doi:10.1021/jz502032c

Cited by 202 publications

(345 citation statements)

References 45 publications

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“…24 Recent evidence suggests that bicarbonate species may form for adsorbents with low amine loadings under humid conditions. 39 Additionally, amines may hydrogen bond with each other and with surface hydroxyls. Previous work has shown that the chemical shift for such amines, in protonated or other charged forms, depending on the counterion.…”

Section: Resultsmentioning

confidence: 99%

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Post-Grafting Amination of Alkyl Halide-Functionalized Silica for Applications in Catalysis, Adsorption, and¹⁵N NMR Spectroscopy

et al. 2015

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An anhydrous synthesis of aminosilica materials from alkyl halide-functionalized mesoporous SBA-15 silica by post-grafting amination is introduced for applications in CO2 adsorption, cooperative catalysis, and (15)N solid-state NMR spectroscopy. The synthesis is demonstrated to convert terminal alkyl halide-functionalized silica materials containing Cl, Br, and I to primary alkylamines using anhydrous ammonia in a high-pressure reactor. The benefits of the post-grafting amination procedure include (i) use of anhydrous isotopically labeled ammonia, (15)NH3, to create aminosilica materials that can be investigated using (15)N solid-state NMR to elucidate potential intermediates and surface species in CO2 adsorption processes and catalysis, (ii) similar CO2 uptake in experiments extracting CO2 from dry simulated air experiments, and (iii) improved activity in acid-base bifunctional catalysis compared to traditional amine-grafted materials. The effects of the type of halide, the initial halide loading, and the total reaction time on the conversion of the halides to primary amines are explored. Physical and chemical characterizations of the materials show that the textural properties of the silica are unaffected by the reaction conditions and that quantitative conversion to primary amines is achieved even at short reaction times and high initial alkyl halide loadings. Additionally, preliminary (15)N solid-state NMR experiments indicate formation of nitrogen-containing species and demonstrate that the synthesis can be used to create materials useful for investigating surface species by NMR spectroscopy. The differences between the materials prepared via post-grafting amination vs traditional aminosilane grafting are attributed to the slightly increased spacing of the amines synthesized by amination because the alkylhalosilanes are initially better spaced on the silica surface after grafting, whereas the aminosilanes likely cluster to a greater extent when grafted on the silica surface. A slight increase in amine spacing allows for more effective amine-silanol interactions in cooperative catalysis without reducing the amine efficiency in CO2 uptake under the conditions used here.

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Section: Resultsmentioning

confidence: 99%

“…[38][39][40][41][42] However, the ability to probe nitrogen-containing species directly through techniques such as 15 N solid-state NMR would be valuable in elucidating more complicated structures on aminosilica materials, so there is a need for a synthesis of such 15 Nlabeled materials.…”

Section: Introductionmentioning

confidence: 99%

Post-Grafting Amination of Alkyl Halide-Functionalized Silica for Applications in Catalysis, Adsorption, and¹⁵N NMR Spectroscopy

et al. 2015

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“…Meanwhile, the other characteristic peaks at 1487 cm À1 corresponding to the ammonium ion bending mode from ammonium carbamate [39,52,53] observed in the fresh CA-S-APS samples, disappeared in the spectra of the deactivated sample. Ammonium carbamate ion pairs, which are formed through the reaction of CO 2 with neighboring amine sites, are the dominant adsorbed CO 2 species in the adsorbents with the strongest CO 2 -amine bonds [39,52]. The loss of this peak further confirms that the CA-S-APS fibers were deactivated upon exposure to SO 2 , leading to the significant reduction of amine density.…”

Section: Materials Characterizationmentioning

confidence: 95%

Stability of amine-based hollow fiber CO2 adsorbents in the presence of NO and SO2

Fan

Rezaei

Labreche

et al. 2015

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h i g h l i g h t s SO 2 -deactivated primary amine fibers reversibly adsorb additional SO 2 . Secondary amine fibers exhibit better SO 2 tolerance than primary amine fibers. Tertiary amine grafted fibers have good SO 2 reversibility under dry or humid conditions. NO does not affect the CO 2 capacity of the fibers over 120 adsorption-desorption cycles. a b s t r a c tComparative studies of the cyclic stability of primary, secondary, and tertiary amine-grafted silica/polymer composite fiber adsorbents upon exposure to simulated flue gas are reported. A simulated dry flue gas mixture with 200 ppm NO does not cause degradation of the amine grafted fiber adsorbents and all fibers retain their CO 2 capacity in the presence of NO. In contrast, upon exposure to dry flue gas in the presence of 200 ppm SO 2 at 35°C, the primary amine containing adsorbent, CA-S-APS, shows a CO 2 capacity reduction of 55% over 120 cyclic adsorption-desorption runs. As the initial SO 2 induced degradation occurs in this adsorbent, the amine sites first irreversibly adsorb SO 2 and then begin to gradually adsorb SO 2 reversibly, as evidenced from a quantitative comparison of the amount of adsorbed SO 2 to the amount of desorbed SO 2 . The secondary amine containing adsorbent, CA-S-MAPS, exhibits an improved stability and approximately 25% CO 2 capacity loss is observed during cycling in the presence of SO 2 . Therefore, the secondary amine based CA-S-MAPS adsorbent demonstrates some degree of tolerance to SO 2 in comparison to the CA-S-APS sample. Under humid conditions, SO 2 imposes significant detrimental impacts on the two adsorbents, as a result of increased SO 2 adsorption capacities in the presence of moisture. Although the CO 2 uptake is nearly zero in the tertiary amine adsorbent, CA-S-DMAPS, the SO 2 capacity of this adsorbent reaches 0.43 mmol/g under humid conditions and this material has the highest SO 2 /N ratio of the fiber adsorbents studied. More importantly, this CA-S-DMAPS sample demonstrates reversible SO 2 adsorption, as indicated from the SO 2 cyclic adsorption experiments. The tertiary amine based fiber adsorbents have good potential for flue gas desulfurization, with advantageous characteristics of high SO 2 /N ratio, excellent reversibility, low CO 2 adsorption and relatively low regeneration temperature.

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“…[15] The types of supported amine sorbents have been groupedi nto four classes (FigureS1i nt he Supporting Information). [20][21][22][23][24] Class 2s pecies are typically more resilient than the class 1s pecies, as the covalent link to the framework limits amine leaching that might occur under some conditions. [18,19] Such materials are attractive because the high density of amine sites achieved leads to high-equilibrium sorbentc apacities and strong CO 2 -binding energies.…”

Section: Introductionmentioning

confidence: 99%

Role of Alumina Basicity in CO₂ Uptake in 3‐Aminopropylsilyl‐Grafted Alumina Adsorbents

et al. 2017

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Oxide-supported amine materials are widely known to be effective CO sorbents under simulated flue-gas and direct-air-capture conditions. Most work has focused on amine species loaded onto porous silica supports, though potential stability advantages may be offered through the use of porous alumina supports. Unlike silica materials, which are comparably inert, porous alumina materials can be tuned to have substantial acidity and/or basicity. Owing to their amphoteric nature, alumina supports play a more active role in CO sorption than silica supports, potentially directly participating in the adsorption process. In this work, primary amines associated with 3-aminopropyltriethoxysilane are grafted onto two different mesoporous alumina materials having different levels of basicity. Adsorbent materials with different amine loadings are prepared, and the CO -adsorption behavior of similar amines on the two alumina supports is demonstrated to be different. At low amine loadings, the inherent properties of the support surface play a significant role, whereas at high amine loadings, when the alumina surface is effectively blocked, the sorbents prepared on the two supports behave similarly. At high amine loadings, amine-CO -amine interactions are shown to dominate, leading to adsorbed species that appear similar to the species formed over silica-supported amine materials. The sorbent properties are comprehensively characterized using N physisorption analysis, in situ FTIR spectroscopy, and adsorption microcalorimetry.

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Effect of Amine Surface Coverage on the Co-Adsorption of CO₂ and Water: Spectral Deconvolution of Adsorbed Species

Cited by 202 publications

References 45 publications

Post-Grafting Amination of Alkyl Halide-Functionalized Silica for Applications in Catalysis, Adsorption, and¹⁵N NMR Spectroscopy

Post-Grafting Amination of Alkyl Halide-Functionalized Silica for Applications in Catalysis, Adsorption, and¹⁵N NMR Spectroscopy

Stability of amine-based hollow fiber CO2 adsorbents in the presence of NO and SO2

Role of Alumina Basicity in CO₂ Uptake in 3‐Aminopropylsilyl‐Grafted Alumina Adsorbents

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Effect of Amine Surface Coverage on the Co-Adsorption of CO2 and Water: Spectral Deconvolution of Adsorbed Species

Cited by 202 publications

References 45 publications

Post-Grafting Amination of Alkyl Halide-Functionalized Silica for Applications in Catalysis, Adsorption, and15N NMR Spectroscopy

Post-Grafting Amination of Alkyl Halide-Functionalized Silica for Applications in Catalysis, Adsorption, and15N NMR Spectroscopy

Stability of amine-based hollow fiber CO2 adsorbents in the presence of NO and SO2

Role of Alumina Basicity in CO2 Uptake in 3‐Aminopropylsilyl‐Grafted Alumina Adsorbents

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Product

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Effect of Amine Surface Coverage on the Co-Adsorption of CO₂ and Water: Spectral Deconvolution of Adsorbed Species

Post-Grafting Amination of Alkyl Halide-Functionalized Silica for Applications in Catalysis, Adsorption, and¹⁵N NMR Spectroscopy

Post-Grafting Amination of Alkyl Halide-Functionalized Silica for Applications in Catalysis, Adsorption, and¹⁵N NMR Spectroscopy

Role of Alumina Basicity in CO₂ Uptake in 3‐Aminopropylsilyl‐Grafted Alumina Adsorbents