The “Missing” Bicarbonate in CO2 Chemisorption Reactions on Solid Amine Sorbents
We have identified a hydrated bicarbonate formed by chemisorption of 13CO2 on both dimethylaminopropylsilane (DMAPS) and aminopropylsilane (APS) pendant molecules grafted on SBA-15 mesoporous silica. The most commonly used sequence in solid-state NMR, 13C CPMAS, failed to detect bicarbonate in these solid amine sorbent samples; here, we have employed a Bloch decay (“pulse-acquire”) sequence (with 1H decoupling) to detect such species. The water that is present contributes to the dynamic motion of the bicarbonate product, thwarting CPMAS but enabling direct 13C detection by shortening the spin–lattice relaxation time. Since solid-state NMR plays a major role in characterizing chemisorption reactions, these new insights that allow for the routine detection of previously elusive bicarbonate species (which are also challenging to observe in IR spectroscopy) represent an important advance. We note that employing this straightforward NMR technique can reveal the presence of bicarbonate that has often otherwise been overlooked, as demonstrated in APS, that has been thought to only contain adsorbed CO2 as carbamate and carbamic acid species. As in other systems (e.g., proteins), dynamic species that sample multiple environments tend to broaden as their motion is frozen out. In this paper, we show two distinct bicarbonate species upon freezing, and coupling to different protons is shown through preliminary 13C–1H HETCOR measurements. This work demonstrates that bicarbonates have likely been formed in the presence of water but have gone unobserved by NMR due to the nature of the experiments most routinely employed, a perspective that will transform the way the sorption community will view CO2 capture by amines.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Center for Understanding and Control of Acid Gas-induced Evolution of Materials for Energy (UNCAGE-ME)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0012577
- OSTI ID:
- 1470675
- Journal Information:
- Journal of the American Chemical Society, Vol. 140, Issue 28; Related Information: UNCAGE-ME partners with Georgia Institute of Technology (lead); Lehigh University; Oak Ridge National Laboratory; University of Alabama; University of Florida; University of Wisconsin; Washington University in St. Louis; ISSN 0002-7863
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Oxidation‐Resistant, Cost‐Effective Epoxide‐Modified Polyamine Adsorbents for CO 2 Capture from Various Sources Including Air
|
journal | April 2019 |
Stability of amine-functionalized CO 2 adsorbents: a multifaceted puzzle
|
journal | January 2019 |
Interfacial assembled preparation of porous carbon composites for selective CO 2 capture at elevated temperatures
|
journal | January 2019 |
Self-supported branched poly(ethyleneimine) materials for CO 2 adsorption from simulated flue gas
|
journal | January 2019 |
Similar Records
Spectroscopic Investigation of the Mechanisms Responsible for the Superior Stability of Hybrid Class 1/Class 2 CO2 Sorbents: A New Class 4 Category
Use of solid state NMR to probe the order, dynamics and conformations of poly(p-phenylene vinylene) and poly(2,5-dimethoxy-p-phenylene vinylene). [NMR (nuclear magnetic resonance)]