Ionic liquids (ILs) have been used for carbon dioxide (CO2) capture, however, which have never been used as catalysts to accelerate CO2capture. The record is broken by a uniquely designed IL, [EMmim][NTf2]. The IL can universally catalyze both CO2sorption and desorption of all the chemisorption‐based technologies. As demonstrated in monoethanolamine (MEA) based CO2capture, even with the addition of only 2000 ppm IL catalyst, the rate of CO2desorption—the key to reducing the overall CO2capture energy consumption or breaking the bottleneck of the state‐of‐the‐art technologies and Paris Agreement implementation—can be increased by 791% at 85 °C, which makes use of low‐temperature waste heat and avoids secondary pollution during CO2capture feasible. Furthermore, the catalytic CO2capture mechanism is experimentally and theoretically revealed.
Implementing Paris Climate Accord is inhibited by the high energy consumption of the state-of-the-art CO2capture technologies due to the notoriously slow kinetics in CO2desorption step of CO2capture. To address the challenge, here we report that nanostructured TiO(OH)2as a catalyst is capable of drastically increasing the rates of CO2desorption from spent monoethanolamine (MEA) by over 4500%. This discovery makes CO2capture successful at much lower temperatures, which not only dramatically reduces energy consumption but also amine losses and prevents emission of carcinogenic amine-decomposition byproducts. The catalytic effect of TiO(OH)2is observed with Raman characterization. The stabilities of the catalyst and MEA are confirmed with 50 cyclic CO2sorption and sorption. A possible mechanism is proposed for the TiO(OH)2-catalyzed CO2capture. TiO(OH)2could be a key to the future success of Paris Climat e Accord.
more » « less- Award ID(s):
- 1632899
- NSF-PAR ID:
- 10154301
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 9
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
null (Ed.)The recalcitrance of some emerging organic contaminants through conventional water treatment systems may necessitate advanced technologies that use highly reactive, non-specific hydroxyl radicals. Here, polyacrylonitrile (PAN) nanofibers with embedded titanium dioxide (TiO 2 ) nanoparticles were synthesized via electrospinning and subsequently carbonized to produce mechanically stable carbon/TiO 2 (C/TiO 2 ) nanofiber composite filters. Nanofiber composites were optimized for reactivity in flow through treatment systems by varying their mass loading of TiO 2 , adding phthalic acid (PTA) as a dispersing agent for nanoparticles in electrospinning sol gels, comparing different types of commercially available TiO 2 nanoparticles (Aeroxide® P25 and 5 nm anatase nanoparticles) and through functionalization with gold (Au/TiO 2 ) as a co-catalyst. High bulk and surface TiO 2 concentrations correspond with enhanced nanofiber reactivity, while PTA as a dispersant makes it possible to fabricate materials at very high P25 loadings (∼80% wt%). The optimal composite formulation (50 wt% P25 with 2.5 wt% PTA) combining high reactivity and material stability was then tested across a range of variables relevant to filtration applications including filter thickness (300–1800 μm), permeate flux (from 540–2700 L m −2 h), incident light energy (UV-254 and simulated sunlight), flow configuration (dead-end and cross-flow filtration), presence of potentially interfering co-solutes (dissolved organic matter and carbonate alkalinity), and across a suite of eight organic micropollutants (atrazine, benzotriazole, caffeine, carbamazepine, DEET, metoprolol, naproxen, and sulfamethoxazole). During cross-flow recirculation under UV-irradiation, 300 μm thick filters (30 mg total mass) produced micropollutant half-lives ∼45 min, with 40–90% removal (from an initial 0.5 μM concentration) in a single pass through the filter. The initial reaction rate coefficients of micropollutant transformation did not clearly correlate with reported second order rate coefficients for reaction with hydroxyl radical ( k OH ), implying that processes other than reaction with photogenerated hydroxyl radical ( e.g. , surface sorption) may control the overall rate of transformation. The materials developed herein represent a promising next-generation filtration technology that integrates photocatalytic activity in a robust platform for nanomaterial-enabled water treatment.more » « less
-
more » « less
Abstract Ammonia is a widely used toxic industrial chemical that can cause severe respiratory ailments. Therefore, understanding and developing materials for its efficient capture and controlled release is necessary. One such class of materials is 3D porous metal‐organic frameworks (MOFs) with exceptional surface areas and robust structures, ideal for gas storage/transport applications. Herein, interactions between ammonia and UiO‐67‐X (X: H, NH2, CH3) zirconium MOFs were studied under cryogenic, ultrahigh vacuum (UHV) conditions using temperature‐programmed desorption mass spectrometry (TPD‐MS) and in‐situ temperature‐programmed infrared (TP‐IR) spectroscopy. Ammonia was observed to interact with μ3−OH groups present on the secondary building unit of UiO‐67‐X MOFs via hydrogen bonding. TP‐IR studies revealed that under cryogenic UHV conditions, UiO‐67‐X MOFs are stable towards ammonia sorption. Interestingly, an increase in the intensity of the C−H stretching mode of the MOF linkers was detected upon ammonia exposure, attributed to NH−π interactions with linkers. These same binding interactions were observed in grand canonical Monte Carlo simulations. Based on TPD‐MS, binding strength of ammonia to three MOFs was determined to be approximately 60 kJ mol−1, suggesting physisorption of ammonia to UiO‐67‐X. In addition, missing linker defect sites, consisting of H2O coordinated to Zr4+sites, were detected through the formation of
n NH3⋅H2O clusters, characterized through in‐situ IR spectroscopy. Structures consistent with these assignments were identified through density functional theory calculations. Tracking these bands through adsorption on thermally activated MOFs gave insight into the dehydroxylation process of UiO‐67 MOFs. This highlights an advantage of using NH3for the structural analysis of MOFs and developing an understanding of interactions between ammonia and UiO‐67‐X zirconium MOFs, while also providing directions for the development of stable materials for efficient toxic gas sorption. -
more » « less
Abstract Ethylene glycol is a widely utilized commodity chemical, the production of which accounts for over 46 million tons of CO2emission annually. Here we report a paired electrocatalytic approach for ethylene glycol production from methanol. Carbon catalysts are effective in reducing formaldehyde into ethylene glycol with a 92% Faradaic efficiency, whereas Pt catalysts at the anode enable formaldehyde production through methanol partial oxidation with a 75% Faradaic efficiency. With a membrane-electrode assembly configuration, we show the feasibility of ethylene glycol electrosynthesis from methanol in a single electrolyzer. The electrolyzer operates a full cell voltage of 3.2 V at a current density of 100 mA cm−2, with a 60% reduction in energy consumption. Further investigations, using operando flow electrolyzer mass spectroscopy, isotopic labeling, and density functional theory (DFT) calculations, indicate that the desorption of a *CH2OH intermediate is the crucial step in determining the selectively towards ethylene glycol over methanol.
-
more » « less
Abstract Multi‐elemental alloy (MEA) nanoparticles have recently received notable attention owing to their high activity and superior phase stability. Previous syntheses of MEA nanoparticles mainly used carbon as the support, owing to its high surface area, good electrical conductivity, and tunable defective sites. However, the interfacial stability issue, such as nanoparticle agglomeration, remains outstanding due to poor interfacial binding between MEA and carbon. Such a problem often causes performance decay when MEA nanoparticles are used as catalysts, hindering their practical applications. Herein, an interface engineering strategy is developed to synthesize MEA–oxide–carbon hierarchical catalysts, where the oxide on carbon helps disperse and stabilize the MEA nanoparticles toward superior thermal and electrochemical stability. Using several MEA compositions (PdRuRh, PtPdIrRuRh, and PdRuRhFeCoNi) and oxides (TiO2and Cr2O3) as model systems, it is shown that adding the oxide renders superior interfacial stability and therefore excellent catalytic performance. Excellent thermal stability is demonstrated under transmission electron microscopy with in situ heating up to 1023 K, as well as via long‐term cycling (>370 hours) of a Li–O2battery as a harsh electrochemical condition to challenge the catalyst stability. This work offers a new route toward constructing efficient and stable catalysts for various applications.
