High Amine Research Articles

Waste organic dye removal using MOF-based electrospun nanofibers of high amine density

The exceptional structural stability of UiO-66 metal–organic framework (MOF) and ligands' functional groups render UiO-66 as a versatile candidate for multiple applications, including wastewater treatment. The possibility of a broad spectrum of post-synthetic modification of UiO-66 further expands its prospective uses. However, commercial applications of UiO-66 have been hindered by the polycrystalline nature of the powder. In this research, modification to obtain UiO-66-NH2 and post-processing with nanofibers comprising chitosan and polyvinyl alcohol (PVA) were applied to faciliate deployment as a suitable option for water decontamination. MOF nanoparticles were post-synthetically modified with 2,4,6-trichloro-1,3,5-triazine (TCT) and 5-phenyl-tetrazole (PT) to produce high-amine containing UiO-66, thus introducing active nitrogen-containing functional groups that enhanced the removal efficiency of targeted molecules from aqueous media. A systematic study was undertaken to optimize the supporting nanofibers and to demonstrate that even a low MOF functionalization, of up to 7- wt%, offered a maximum methyl orange adsorption capacity of 619 mg/g, superior to most adsorbents reported so far. Furthermore, selectivity, regeneration ability, and the effect of ambient conditions were demonstrated.

Amine-Impregnated Porous Organic Polymers with Chemisorption Sites for Highly Efficient CO2 Chemical Conversion under Ambient Conditions

CO2 cycloaddition with epoxides is an important chemical process for CO2 conversion to generate cyclic carbonates, which are major sources and intermediates of fine chemicals and electrolytes. Unfortunately, the catalytic efficiency of various porous organic polymers (POPs) for the CO2 cycloaddition process remains poor and necessitates severe conditions or a prolonged reaction time at mild temperature and pressure. Only a few reports have emphasized the improvement of the interaction among POP heterogeneous catalysts with CO2, in addition to many attempts to boost efficiency by increasing the adsorption capacity of POPs for CO2. Furthermore, chemisorption, which can efficiently adsorb and activate CO2, could be used to establish a high binding affinity and interaction among POPs and CO2. Herein, we report amine-impregnated porous organic polymers, i.e., hyper-cross-linked polymer (HCP)-tetraphenylporphyrin (TPP), using a wet impregnation method that differentiates itself from the chemical grafting method due to the simplicity of sample preparation and high amine loading to create abundant CO2 chemisorption sites to effectively adsorb and activate CO2 for easier cycloaddition reactions under mild conditions. The amine-functionalized heterogeneous catalysts HCP-TPP-Co-EDA-10 and HCP-TPP-Co-PEI-5 showed a strong binding affinity with CO2 (Qst value of 31.8 and 52.5 kJ mol–1) and high catalytic yield (reaching up to 99%) under mild temperature and pressure. Interestingly, the turnover number (TON) and turnover frequency (TOF) could reach up to 6930 and 193 h–1, respectively, which are one of the highest values reported so far under mild conditions. Furthermore, HCP-TPP-Co-EDA-10 and HCP-TPP-Co-PEI-5 have excellent recyclability and stability (more than five recycling times) for CO2 conversion. Additionally, a possible mechanism is also proposed for the catalytic conversion reaction. This simple strategy of utilizing amines as chemisorption sites for CO2 is demonstrated as an approach to designing highly efficient functionalized hyper-cross-linked polymers (HCPs) for CO2 capture and chemical conversion.

Amine-impregnated porous carbon–silica sheets derived from vermiculite with superior adsorption capability and cyclic stability for CO2 capture

Amine-functionalized adsorbents have become one of the most promising capture technologies for greenhouse gas mitigation. However, developing cost-effective adsorbents with high adsorption capacity and superior cyclic stability via temperature swing adsorption remains difficult. Herein, sandwich-like polyethyleneimine (PEI)-impregnated porous carbon–silica sheets derived from vermiculite (AEVCP) adsorbents were successfully synthesized via porous carbon network confined within acid activated expanded vermiculite derived silica (AEV) sheets and interlayer amine-functionalization with PEI impregnation. The effect of adsorption temperature on CO2 adsorption performances, adsorption/desorption kinetics and thermodynamics for AEVCP adsorbents were specifically discussed. The optimal AEVCP50 adsorbent possessed a large CO2 uptake of 1.84 mmol/g at 75 ℃ in 60 vol% CO2/40 vol% N2 and superior cyclic stability with 7.6 % decay after 10 cycles, due to the hierarchical porous structure and high thermal conductivity of porous carbon–silica sheets derived from vermiculite (AEVC) support. The unique sandwich-like features of AEVC support are favorable for the high amine loading, rapid CO2 diffusion and efficient capture. The interlayer carbon implantation and amine-functionalization with strong interlayer spatial confinement effect, can suppress the formation of urea linkages, avoid the persistent over-heating and excess amine agglomeration, and enhance the gas diffusion and thermal transfer during the adsorption isobar process, which ultimately lead to superior adsorption capability and cyclic stability for CO2 capture. This design approach of cost-effective adsorbents derived from natural minerals provides a new avenue for practical CO2 capture and separation processes.

Enantioselective Transformations from Nitriles to NH2 -α-Tertiary Amines.

Organic molecules, containing one or more amine chiral centers, are very common to see in natural products and medicines. Although a large number of methods have been developed to afford enantiopure amines, most of the known approaches are limited with various reasons. For example, many methodologies start from nitrogen protected and activated substrates, which usually need multistep operations and seriously decrease the atom economy. Here we disclose a new catalytic strategy from commercial nitriles to high enantioselective α-tertiary primary amines in up to 90 % yield and 95 % enantiomeric excess. This transformation firstly undergoes an addition process of organolithium reagents to nitriles to generate the imine intermediates in situ. Subsequently, the most challenging step is by employing copper catalytic enantioselective addition of AllylBpin to the imine intermediates to form the final amines in one pot.

Self-catalyzed Gelling Synthesis of Aerogels with Inorganic and Organic Nanocomponents for Thermal Insulation and CO2 Capture

Silica aerogels have already been recognized as potential candidates in the fields of thermal insulation, sorption, and separation, but the intrinsic brittleness and cumbersome preparation process limit their broad applications. In this work, a simple self-catalyzed gelling strategy was applied to prepare organic–inorganic in situ hybrid aerogels (OIHAs) derived from bis[3-(triethoxysilyl)propyl]amine (BTPA) and methyltrimethoxysilane (MTES). The Si–CH3 groups from MTES make it possible for OIHAs to be prepared through ambient drying and exhibit good hydrophobicity. Owing to the alkalinity of the amine groups from BTPA, self-catalyed hydrolyzation and condensation reactions occur between two silicon precursors to build a uniform pearl-chain nanoporous structure. The high specific surface area and amine groups existing on the nanoskeleton surface of the obtained OIHAs endow them with fascinating CO2 capture ability up to 5.89 mmol/g at 298 K and 100 kPa, which are significantly higher than the values of other aerogels reported under the similar conditions. Furthermore, ultralow thermal conductivity (as low as 20.1 mW/(m·K) at 25 °C), high strength (up to 2.38 MPa), and great elasticity (fully recoverable elastic strain of 14%) are achieved together for the OIHAs due to the organic–inorganic in situ cross-linked architecture. The as-prepared OIHAs with versatile properties have great application prospects in the fields of building thermal insulation and CO2 capture. The self-catalyzed gelling strategy provides an alternative routine for the simple preparation of silica-based aerogels.

Porphyrin-MOF-derived carbon-encapsulated copper as a selective and leaching resistant catalyst for the hydrogenation of nitriles

BackgroundDesigning high-selective and low-cost catalysts for the selective hydrogenation of nitriles to high value-added amines is important and challenging. MethodsHerein, a non-noble metal Cu@NC-ZrO2 catalyst was prepared by simple pyrolysis using PCN-222(Cu) MOF as the precursor. Significant findingsUnder lower temperature pyrolysis, the small Cu nanoparticles (NPs) and abundant Cu-Nx active sites were uniformly embedded in the N-doped support and the produced catalyst retains the mesoporous structure of PCN-222(Cu), which are beneficial for catalytic performance. The Cu@NC-ZrO2–600 catalyst was found to be economic and efficient for the selective hydrogenation of benzonitrile to benzylamine, and the selectivity and conversion can be up to 100% and 95%, respectively. Moreover, due to the encapsulation of Cu nanoparticles in the support N-doped carbon matrix, this catalyst showed outstanding stability of resistance to leaching.

Efficient conversion of furfural to furfural amine over 4Ru1Co/AC catalyst

The production of amine intermediates from biomass is capturing increasing attention. Herein, an efficient conversion of furfural to furfural amine over RuCo/AC catalyst under hydrothermal conditions has been investigated. The effects of different carriers, bimetals, and reaction conditions were systematically investigated in green solvents (water). Fully conversion of furfural and high furfural amine yield (92.13%) at 80 ℃ for 1 h over 4Ru1Co/AC. The excellent catalytic performance of 4Ru1Co/AC was attributed to its high acidity and good hydrogenation ability, as well as the synergistic effect between Ru-Co alloy formations and the activated carbon. Importantly, the highly selective preparation of furfural to furfural amine is a promising way to high-value utilization of cellulosic biomass in green solvents.

High separation performance of carbon dioxide-based poly(ether-carbonate) copolymer for gas chromatographic analyses

This work presents the investigation of a novel CO2-based poly(ether-carbonate) copolymer, namely poly(propylene ether-carbonate)diol (PPCD), for gas chromatographic (GC) analyses. The PPCD column exhibited column efficiency of 4000 plates/m determined by naphthalene at 120 ℃ with the retention factor 6.23. Its separation performance was investigated by adopting a wide variety of analytes and isomers, including the isomer mixtures of alkanes, substituted benzene isomers with diverse groups, phenols and anilines, and the mixtures of organic solvents of high volatility, aliphatic amines and N-heterocycles. As a result, the PPCD column displayed distinctly higher resolving capability than the commercial columns described herein and achieved high column inertness towards acidic/basic analytes without involving any deactivation procedure. Additionally, it displayed excellent separation repeatability and reproducibility with the relative standard deviation (RSD) values less than 0.01% for within-day and in the range of 0.26% – 0.36% for between-day and 3.0% – 4.1% for between-column (n = 4). Further, the PPCD column (30 m) was used to GC–MS analysis of the lemongrass essential oil and resolved more components well than the indicated commercial columns, evidencing its outstanding separation performance for analyses of complex samples. Up to date, the CO2-based poly(ether-carbonate) copolymers are not reported in the field of chromatography. This work demonstrates their promising future as a new type of selective and inert stationary phases for practical GC analyses.

Dry gel grafting of mesoporous silica: Application to amine-based CO2 adsorbents

A dry gel tumbling (DGT) method, which combines solution and gas phase grafting procedures, is presented as an energy- and cost-effective, and scalable route for the preparation of hybrid organosilica materials. For illustration, the preparation, characterization and performance of amine-grafted CO2 adsorbents (AGAs) is presented in detail. Materials prepared by DGT performed better compared to those derived from an optimized water-aided grafting procedure in toluene. Unusually high amine content (4.53 mmol/g), CO2 capacity (2.08 mmol/g) and amine efficiency (0.46) were obtained for this material. DGT offers maximum incorporation of organosilanes during grafting, i.e., an efficient and high yield reaction between the surface silanol groups and the alkoxyl groups of the silane, with grafting efficiencies >95% for propylamine-grafted adsorbents. The method was extended to the synthesis of hydrophobic AGAs, with increased resistance to leaching.

Hydrogen Borrowing: towards Aliphatic Tertiary Amines from Lignin Model Compounds Using a Supported Copper Catalyst.

Upcoming biorefineries, such as lignin-first provide renewable aromatics containing unique aliphatic alcohols. In this context, a Cu-ZrO2 catalyzed hydrogen borrowing approach was established to yield tertiary amine from the lignin model monomer 3-(3,4-dimethoxyphenyl)-1-propanol and the actual lignin-derived monomers, (3-(4-hydroxyphenyl)-1-propanol and dihydroconiferyl alcohol), with dimethylamine. Various industrial metal catalysts were evaluated, resulting in nearly quantitative mass balances for most catalysts. Identified intermediates, side and reaction products were placed into a corresponding reaction network, supported by kinetic evolution experiments. Cu-ZrO2 was selected as most suitable catalyst combining high alcohol conversion with respectable aliphatic tertiary amine selectivity. Low pressure H2 was key for high catalyst activity and tertiary amine selectivity, mainly by hindering undesired reactant dimethylamine disproportionation and alcohol amidation. Besides dimethylamine model, diverse secondary amine reactants were tested with moderate to high tertiary amine yields. As most active catalytic site, highly dispersed Cu species in strong contact with ZrO2 is suggested. ToF-SIMS, N2 O chemisorption, TGA and XPS of spent Cu-ZrO2 revealed that imperfect amine product desorption and declining surface Cu lowered the catalytic activity upon catalyst reuse, while thermal reduction readily restored the initial activity and selectivity demonstrating catalyst reuse.

Amination-mediated nano eye-drops with enhanced corneal permeability and effective burst release for acute glaucoma treatment

The development of topical formulations with advanced functions to overcome the poor and sluggish permeability/bioavailability of traditional eye drops into interior of the eye is significantly important for efficient management of acute intraocular diseases. For the first time, we herein exploit the amination level effects of chitosan coatings for facilitating a fast penetration of ceria nanocapsules (NCs) through the corneal barriers followed by triggering an effective burst release of pilocarpine in a controlled manner. Specifically, high amination level can help to improve the permeability of the ceria NCs through corneal cell layers by ∼ 43 folds while endowing the carriers with the most effective burst release performance. In an experimental rabbit model of acute glaucoma, a single dose topical instillation of pilocarpine-loaded chitosan-coated ceria NCs could effectively reduce the extremely high intraocular pressures to normal, prevent damage of endothelium (precluding ∼ 98.7 % cell death), open the angle closure, and inhibit retinal degeneration (impeding ∼ 98 % of retinal axon loss) at 4 h post-treatment. These findings show a great promise for the development of nano eye-drops for efficient management of acute glaucoma and other acute diseases that need prompt treatments.

Novel alkanolamine-based biphasic solvent for CO2 capture with low energy consumption and phase change mechanism analysis

Biphasic solvents for CO2 capture have received significant attention due to their potential for energy conservation. However, traditional biphasic solvents result in highly viscous CO2 rich-phases and high amine losses. To overcome these drawbacks, we have developed a novel alkanolamine-based biphasic solvent by blending 2-(methylamino) ethanol (MAE), 3-(dimethylamino)propan-1-ol (3DMA1P), diethylene glycol dimethyl ether (DGM), and water. The aqueous MAE/3DMA1P/DGM solvent showed a cyclic capacity of 0.45 mol CO2/mol amine, which is 1.8 times that of monoethanolamine (MEA), and a desorption rate and regeneration efficiency twice those of MEA. The viscosity of the biphasic solvents can be reduced to 13.12 mPa⋅s at 313 K, which is lower than that of reported biphasic solvents. The evaluated regeneration energy was 2.33 GJ/ton CO2. Cation chromatography measurements revealed the tendency of MAE to accumulate in the CO2-rich phase with increasing CO2 absorption loading. Quantitative 13C NMR analyses were performed to investigate the species distribution in both phases, and DGM was found to be the major component of the CO2-lean phase. Different solubilities of the MAE molecules and MAE carbamate in DGM resulted in phase separation. Molecular dynamics (MD) simulations on the CO2-unloaded and CO2-loaded solutions verified the phase separation mechanism. MAE molecules tended to cluster, and the interactions between MAE and DGM dropped significantly, with increasing DGM concentration.

Alleviation of Metabolic Disturbance by Substituting Kanjang High in Bacillus for Salt through Modulation of Gut Microbiota in Estrogen-Deficient Rats.

A high salt intake may exacerbate menopausal symptoms and substituting for different types of traditionally made kanjang (TMK; soy sauce) may prevent it. This study examined whether substituting salt with lyophilized TMK containing low and high Bacillus and biogenic amines in a high-fat diet might modulate the menopausal symptoms and the energy, glucose, and lipid metabolism in ovariectomized (OVX) rats. They were categorized into salt (Control), TMK with high Bacillus and low biogenic amines (HBLB), TMK with high Bacillus and high biogenic amines (HBHB), TMK with low Bacillus and low biogenic amines (LBLB), and TMK with low Bacillus and high biogenic amines (LBHB). Sham-operated rats consumed the same diet as the Control. HBLB, HBHB, and LBHB prevented increased tail skin temperature compared to the Control. HBHB and HBLB partially inhibited the increased weight gain and abdominal fat mass by reducing the food efficiency without changing the serum 17β-estradiol concentrations. Serum glucose and insulin concentrations and the insulin resistance index by the homeostatic model assessment for insulin resistance showed a positive association for weight gain. HBLB and HBHB decreased the serum malondialdehyde and tumor-necrosis factor-α levels. Hepatic triglyceride storage was lower in all TMK groups than in the Control, while hepatic glycogen accumulation was higher in the HBLB, HBHB, and LBHB groups than in the Control and LBLB groups. Accordingly, the mRNA expression of peroxisome proliferator-activated receptors-γ(PPAR-γ) was higher in the HBLB and HBHB groups compared to the Control, and that of fatty acid synthase was opposite to PPAR-γ expression. However, HBLB and HBHB improved dyslipidemia and insulin resistance compared to the Control, but their improvement did not reach that of the Normal-control. The acetic acid concentrations in the portal vein were lower in the LBLB than in the Control, while the butyric acid contents were higher in the LBHB and HBLB groups than in the Control. HBHB, HBLB, and LBHB elevated Akkermansia and Lactobacillus, and HBLB and LBLB increased Bacteroides and Ruminococcus compared to the Control. Polycyclic aromatic hydrocarbon degradation, bile acid synthesis, and unsaturated fatty acid biosynthesis were significantly higher in the HBLB group than in the Control group. In conclusion, substituting salts to TMK with a high Bacillus content regardless of the bioamine contents partially improved the menopausal symptoms and metabolic disturbance in estrogen-deficient animals.

Epoxide functionalization of a pentaethylenehexamine adsorbent supported on macroporous silica for post-combustion CO2 capture

N-functionalized solid adsorbents have been studied for post-combustion CO2 capture. Most studies have focused only on the adsorption condition of the adsorbents. Few studies have focused on the regeneration condition of adsorbents. Regeneration is required under the condition of 100 % CO2 for high-purity CO2 separation. Regeneration under inert conditions such as N2 or He, not under the condition of 100 % CO2 regeneration are required additional cost for high-purity CO2 separation. In this study, a macroporous silica (MPS) support, which combined a high surface area, large porosity and large pore volume, was selected as the support to achieve high CO2 capture performance. Pentaethylenehexamine (PEHA) was selected because of its high amine content, high adsorption capacity, high thermal stability, and low cost. The epoxide functionalization of PEHA was used to suppress the urea formation under regeneration conditions. The working capacity and cyclic stability of epoxide functionalization of MPS-based PEHA adsorbents were investigated. A working capacity of 1.8 mmol g−1 was maintained by repeating adsorption and desorption experiments 20 times under an adsorption condition of 15 % CO2 and a desorption condition of 100 % CO2. Additionally, the stability of the adsorbent under a 100 % CO2 regeneration condition was confirmed by maintaining the working capacity constant during 20 repeated adsorption and desorption cycle experiments. When the adsorption time was reduced to minimize H2O adsorption, the regeneration heat of the adsorbent was 2.86 GJ tCO2-1. These results demonstrated that the regeneration ability was excellent under the condition of 100 % CO2, which is the actual process application condition. This approach is promising for industrial applications of CO2 capture technology.

Amine functionalized mesocellular silica foam as highly efficient sorbents for CO2 capture

A series of amine-functionalized CO2 sorbents were synthesized by grafting mono- and tri-amine substituted trialkoxysilanes on mesocellular siliceous foam (MCF) via a facile wet grafting method. The effect of amine type, amine loading level, and porous structure of silica on the CO2 adsorption performance was investigated. MCF silica with a three-dimensional (3D) interconnected porous structure was found to be suitable for preparing amine-grafted sorbents. Tested at 25 °C and 0.15 bar of CO2, the mono- and tri-amine grafted MCFs exhibited a fast adsorption rate and excellent CO2 adsorption capacity of 1.71 mmol/g for mono-amine and 2.07 mmol/g for tri-amine, which was much higher than amine grafted PQ and SBA-15 with a 2D porous structure, and the amine grafted silica sorbents prepared in previous studies. The large pore volume and pore size coupled with superior interconnectivity of MCF enable more surface silanol groups available and accessible for amino silanes, leading to a high amine loading level and excellent amine dispersion on the silica surface, which enhances both the CO2 adsorption capacity and adsorption rate of the developed sorbents. Cyclic adsorption–desorption tests confirmed the excellent stability of the amine grafted MCF.

Preparation of a Fiber-Like 3D-Structured Adsorbent for CO2 Capture.

Solid amine adsorbents are promising materials to mitigate global warming. In this study, a commercially available melamine-formaldehyde sponge was adopted as a support to prepare a kind of solid amine adsorbent using polyethylenimine as a functional component and ethylene glycol diglycidyl ether as a cross-linker. The adsorbent, with abundant tunnels and a high amine loading amount, had a high adsorption capacity. When the amine loading was 89.6 wt%, the as-prepared adsorbent showed a high adsorption capacity of 7.29 mmol/g at 20 °C in the presence of water. The spent adsorbent could be easily regenerated by heating it at 90 °C, resulting in lower energy consumption. It has been proved by the Avrami model that physical and chemical adsorption coexist in the adsorption of CO2 on this adsorbent. Simulation with the intraparticle diffusion model has revealed that the rate-controlling step in the adsorption process was the gas film diffusion period when the adsorption temperature was below 30 °C, while it was the adsorption equilibrium period when the adsorption temperature was above 30 °C.

Volatile Products of the Autoxidation of Poly(ethylenimine) in CO2 Sorbents

Poly(ethyleneimine) (PEI)-based CO2 sorbents are a promising material class for use in CO2 capture applications, particularly direct air capture (DAC), due to their high amine content and CO2 capacities. The sorbent lifetime is a key uncertainty in the deployment of these materials in such applications, as they oxidize under conditions relevant to candidate DAC process cycles. Here, we utilize thermogravimetric analysis/differential scanning calorimetry/FTIR spectroscopy to characterize the nature, rate, and quantity of volatile species formed from the oxidation of PEI when supported on mesoporous Al2O3. We show that NH3, CO2, and H2O are primary volatile species formed from PEI oxidation and that their production rate matches the overall oxidation rate as measured via heat flow from a differential scanning calorimeter. We show that the total quantity of NH3 evolved is consistent with terminal primary amines being cleaved from the polymer chain and that approximately one hydrogen atom per PEI repeat unit reacts to form H2O during the reaction. Finally, metadynamics and quantum chemical simulations performed on a simplified system are used to highlight the likely importance of radicals in the elementary reactions that comprise the oxidation reaction set. The findings here represent the first characterization of the volatile products from the oxidation of PEI in CO2 sorbents and lead to a greater understanding of the mechanisms behind the oxidative degradation of these materials.

Accessible amino-rich ordered mesoporous silica for carbon dioxide capture

In this work, we reported a strategy on how to utilize CO2 in synthesizing adsorbent materials, which were then applied in CO2 capture. The innovation was the first discovery of carbon dioxide as a special weak acid in aqueous solution to adjust the interaction between the anionic surfactant and the amino-silane, which simultaneously achieved high amine content, well-ordered mesopores, and high surface area, thereby achieving high-efficiency adsorption of CO2. An adsorption capacity of over 5.0 wt% for CO2 uptake at 30 °C and a regeneration of over 30 adsorption–desorption cycles were proven that it was a good adsorbent for CO2 capture. In addition, this adsorbent was easily regenerated at a relatively low temperature of 90 °C. Therefore, it showed great potential for CO2 capture considering the energy-saving and the environmental aspects.

High amine emissions formation and aerosol particle size distribution in post-combustion CO2 capture process

Amine emissions in the CO2 absorption system may lead to solvent loss and cause a series of environmental problems, especially in high nuclear scenario. In the 3.6 Nm3/h test bench, when the simulated flue gas passes through the absorber, the particle concentration dropped sharply from 3.43 × 107 cm−3 to 4.41 × 106 cm−3. The total MEA emissions reached 1519 mg/Nm3 at the outlet of the absorber, including 476 mg/Nm3 vapor-type amine. By overcoming the difficulty of measuring high-quality liquid particles, the results of particle size distribution (PSD) provided a revealing insight into aerosol growth. The changing trend of amine emissions was completely consistent with total particle emissions. High absorption reaction intensity can be achieved with lower lean solvent CO2 loading, appropriate CO2 concentration (12%), and higher solvent temperature (only for small absorbers). Then, more droplets grew up to near-micron level (> 733 nm), causing total particle emissions increased dramatically to 3500–6000 mg/Nm3. Considering the CO2 absorption system is equipped with a water wash column and demister, the absorber outlet particle with a size less than 1 μm (PM1) will be the main threat. The PM1 emissions and control strategies were discussed based on the PSD data. It is recommended to promote aerosol growth after the absorber rather than restrain it in the absorber.

Amine-incorporated adsorbents with reversible sites and high amine efficiency for CO2 capture in wet environment

CO2 adsorption in wet environments is attractive but difficult in terms of the unsatisfied adsorption capacity and low efficiency of active sites. Herein, we report the fabrication of a thermal-responsive adsorbent with reversible amine sites by copolymerizing N-acryloyl glycinamide (NAGA), N-[3-(dimethylamino)propyl]methacrylamide (DMAPM), and styrene (ST). During adsorption at 20 °C, the tertiary amines of the DMAPM units stretch out and act as the strong sites in water. The adsorption capacity can reach 98 mL g−1, corresponding to the highest amine efficiency (0.99 mol CO2 per mol amine), which is superior to most reported adsorbents. When elevating temperature for desorption, these active sites are shielded in the adsorbent particles because of the formation of intramolecular hydrogen bonds between the NAGA and DMAPM units. The exquisite utilization of thermal responsiveness endows the adsorbents with reversible amine sites and high amine efficiency, making them promising in practical CO2 capture.