Highly efficient and reversible CO2 capture by tunable anion‐functionalized macro‐porous resins

Anion functionalized strategy has been proposed for the synthesis of macro‐porous resins [IRA‐900][An] through the neutral reaction of the basic resin [IRA‐900][OH] with the corresponding donors. Combining CO₂ adsorption results and FT‐IR, solid‐state ¹³C NMR characterization as well as quantum chemical calculations, chemical adsorption mechanism was verified and tunable capture of CO₂ was realized. Among them, the anion functionalized resin [IRA‐900][Triz] exhibits an extremely high adsorption capacity (4.02 mmol g^?1 at 25°C, 0.15 bar), outperforming many other good adsorbents. Finally, we discuss the thermostability and recycling stability of [IRA‐900][Triz], which shows a great potential in the industrial capture of CO₂. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3008–3015, 2017     

Gas solubility in long‐chain imidazolium‐based ionic liquids

The gas solubility in 1‐dodecyl‐3‐methylimidazolium [C₁₂MIM] based ionic liquids (ILs) was measured at temperatures (333.2, 353.2, and 373.2) K and pressures up to 60 bar for the first time. The popular UNIFAC‐Lei model was successfully extended to long‐chain imidazolium‐based IL and gas (CO₂, CO, and H₂) systems. The free volume theory was used to explain the gas solubility and selectivity in imidazolium‐based ILs by calculating the fractional free volume and free volume by the COSMO‐RS model. Furthermore, the excess enthalpy of gas‐IL system was concerned to provide new insights into temperature dependency of gas (CO₂, CO, and H₂) solubility in ILs. The experimental data, calculation, and theoretical analysis presented in this work are important in gas separations with ILs or supported ionic liquid membranes. © 2017 American Institute of Chemical Engineers AIChE J, 63: 1792–1798, 2017     

Environment‐friendly chemical recycling of aliphatic polyurethanes by hydrolysis in a CO2‐water system

In order to develop a chemical recycling system of polyurethanes (PUs), environment‐friendly hydrolysis of two types of aliphatic PUs was studied under pressured CO₂ in water, in which the carbonic acid generated from CO₂ acted as an acid catalyst. Two PUs, namely H‐PU or I‐PU, were synthesized starting from 1,4‐butanediol and 1,6‐hexamethylene diisocyanate or isophorone diisocyanate, respectively. The hydrolysis of PUs depended on the experimental conditions, such as the temperature and CO₂ pressure. As a result, 98% of H‐PU and 91% of I‐PU were successfully hydrolyzed under the typical conditions of 190 °C for 24 h at 8.0 MPa CO₂. The reaction mixtures afforded 1,4‐butanediol and diamines without the formation of any byproducts. Both of these raw materials generated from the originated PUs by selective hydrolytic cleavage of the urethane linkages, and they were easily isolated in high yields simply by evaporation of the water‐soluble components within the reaction mixture. By comparing the results of the two aliphatic PUs with those of an aromatic PU (M‐PU), the hydrolyzability was found to decrease in the order H‐PU, I‐PU, and M‐PU. The difference can be ascribed to the hydrophilicity of the aliphatic or aromatic groups connected to the urethane moieties at the terminals of PUs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45897.     

Layer‐by‐layer modification of porous polybenzoxazine with silver nanoparticles for enhanced CO2 storage

Polybenzoxazine (PBZ) xerogels have been synthesized via quasi solventless method and coated with silver nanoparticles using the layer‐by‐layer (LbL) deposition method. After coating, the samples were carbonized at 800 °C to obtain high surface area porous carbon materials to be used for CO₂ storage. Evidences of the successful LbL deposition of the coating was provided by ultraviolet–visible and attenuated total reflection–Fourier transform infrared spectroscopy and the silver nanoparticles top layer was confirmed by scanning electron microscopy–energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy. Results showed that the samples coated with silver nanoparticles displayed an increased CO₂ capacity from 3.02 to 3.39 mmol g^?1 when compared with the plain carbon PBZ. The LbL method for the modification of the pore surface in porous PBZ is simple and allows the facile tuning of the inner PBZ pore's surface chemistry with metallic nanoparticles that could be enhanced CO₂ storage capacity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45097.     

Foaming of poly(ethylene‐co‐vinyl acetate) and poly(ethylene‐co‐vinyl acetate‐co‐carbon monoxide) and their blends with carbon dioxide

Poly(ethylene‐co‐vinyl acetate) (EVA‐25) and poly(ethylene‐co‐vinyl acetate‐co‐carbon monoxide) (EVACO‐2410) and their blends with EVACO:EVA ratios of 80:20, 60:40, 40:60, and 20:80 were foamed using CO₂. These foams are of interest for applications ranging from footwear to medical devices. Foaming experiments were carried out using 1 mm thick melt‐extruded films in CO₂ at a range of pressures (100, 200, and 300 bar) and temperatures (30, 40, 50, and 60 °C). Foamability of the polymers was explored both under isothermal and gradient temperature conditions. Foams of EVACO‐2410 displayed high initial expansions followed by postfoaming relaxation and shrinkage while foams generated from EVA‐25 showed more dimensional stability. Blending EVACO‐2410 with EVA‐25 was explored as an approach to reduce postfoaming relaxation and shrinkage. The surfaces of the foamed samples displayed blistering that was linked to CO₂ bubble entrapment and coalescence at the surface. Scanning electron micrographs of the foams generated from blends displayed distinct morphologies reflecting whether the sections were representing the machine‐ or cross‐machine direction of extruded films. In going from EVACO‐2410 to EVA‐25, the cell densities ranged from about 10⁶ to 10¹⁰ cells/cm³. Foams with low bulk densities of about 0.11 g/cm³ could be generated. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45841.     

Conversion of carbohydrates into 5‐hydroxymethylfurfural in a green reaction system of CO2‐water‐isopropanol

In this work, a green reaction system of CO₂‐water‐isopropanol was developed for 5‐hydroxymethylfurfural (HMF) production. The conversion of fructose in a CO₂‐water system was first investigated, and the results showed this system could promote the formation of HMF compared to a pure water system. Then, isopropanol was introduced into the CO₂‐water system and the HMF formation became better because the solvent effect of isopropanol increased the tautomeric composition of fructofuranose, which was easy to form HMF. The existence of isopropanol was found to greatly suppress secondary reactions where HMF was converted to levulinic acid and insoluble humin. Meanwhile, the effects of reaction parameters on the conversion of fructose to HMF in the CO₂‐water‐isopropanol system were analyzed, and a high HMF yield of 67.14% was obtained. Finally, to further illustrate the merits of CO₂‐water‐isopropanol system, productions of HMF from other carbohydrates were tested and satisfactory yields were achieved. © 2016 American Institute of Chemical Engineers AIChE J, 63: 257–265, 2017     

CO2‐facilitated transport through poly(N‐vinyl‐γ‐sodium aminobutyrate‐co‐sodium acrylate)/polysulfone composite membranes

Poly(N‐vinyl‐γ‐sodium aminobutyrate‐co‐sodium acrylate) (VSA–SA)/polysulfone (PS) composite membranes were prepared for the separation of CO₂. VSA–SA contained secondary amines and carboxylate ions that could act as carriers for CO₂. At 20°C and 1.06 atm of feed pressure, a VSA–SA/PS composite membrane displayed a pure CO₂ permeation rate of 6.12 × 10^?6 cm³(STP)/cm² s cmHg and a CO₂/CH₄ ideal selectivity of 524.5. In experiments with a mixed gas of 50 vol % CO₂ and 50 vol % CH₄, at 20°C and 1.04 atm of feed pressure, the CO₂ permeation rate was 9.2 × 10^?6 cm³ (STP)/cm² s cmHg, and the selectivity of CO₂/CH₄ was 46.8. Crosslinkages with metal ions were effective for increasing the selectivity. Both the selectivity of CO₂ over CH₄ and the CO₂ permeation rate had a maximum against the carrier concentration. The high CO₂ permeation rate originated from the facilitated transport mechanism, which was confirmed by Fourier transform infrared with attenuated total reflectance techniques. The performance of the membranes prepared in this work had good stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 275–282, 2006     

The analysis of solubility,absorption kinetics of CO2 absorption into aqueous 1‐diethylamino‐2‐propanol solution

In this present work, the CO₂ absorption performance of aqueous 1‐diethylamino‐2‐propanol (1DEA2P) solution was studied with respect to CO₂ equilibrium solubility, absorption kinetics, and absorption heat. The equilibrium solubility of CO₂ in 2M 1DEA2P solution was measured over the temperature range from 298 to 333 K and CO₂ partial pressure range from 8 to101 kPa. The absorption kinetics data were developed and analyzed using the base‐catalyzed hydration mechanism and artificial neural network models (radial basis function neural network [RBFNN] and back‐propagation neural network [BPNN] models) with an acceptable absolute average deviation of 10% for base‐catalyzed hydration mechanism, 2.6% for RBFNN model and 1.77% for BPNN model, respectively. The CO₂ absorption heat of 1DEA2P was estimated to be ?43.6 kJ/mol. In addition, the ions (1DEA2P, 1DEA2PH⁺, , CO₃^2?) speciation plots of the 1DEA2P‐CO₂‐H₂O system were developed to further understand the reaction process of 1DEA2P with CO₂. Based on a comparison with conventional amines (e.g., MEA, DEA, MDEA) and alternative amines (i.e., 1DMA2P and 4‐(diethylamino)?2‐butanol [DEAB]), 1DEA2P exhibited good performance with respect to CO₂ equilibrium solubility, reaction kinetics, and CO₂ absorption heat. Meanwhile, the overall evaluation of 1DEA2P for application in CCS in terms of absorption and desorption is presented, giving helpful information for the screening of these novel amines. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2694–2704, 2017     

A new model for correlation and prediction of equilibrium CO2 solubility in N‐methyl‐4‐piperidinol solvent

In this work, the equilibrium CO₂ solubility in the aqueous tertiary amine, N‐methyl‐4‐piperidinol (MPDL) was measured over a range of temperatures, CO₂ partial pressures and amine concentrations. The dissociation constant of the MPDL solution was determined as well. A new thermodynamic model was developed to predict the equilibrium CO₂ solubility in the MPDL‐H₂O‐CO₂ system. This model, equipped with the correction factor (C_f), can give reasonable prediction with an average absolute deviation of 2.0%, and performs better than other models (i.e., KE model, Li‐Shen model, and Hu‐Chakma). The second‐order reaction rate constant (k₂) of MPDL and the heat of CO₂ absorption (–ΔH_abs) into aqueous MPDL solutions were evaluated as well. Based on the comparison with some conventional amines, MPDL revealed a high‐equilibrium CO₂ loading, reasonably fast absorption rate when compared with other tertiary amines, and a low energy requirement for regeneration. It may, therefore, be considered to be an alternative solvent for CO₂ capture. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3395–3403, 2017     

Study of solubility and swelling ratio in polymer‐CO2 systems using the PC‐SAFT equation of state

We use the PC‐SAFT equation of state to model the solubility of CO₂ in various homopolymers. We also model the swelling ratio of the PP (polypropylene)‐CO₂ mixture using PC‐SAFT and then compare the results with Sanchez‐Lacombe (S‐L) and Simha‐Somcynsky (S‐S) equations. The results show that PC‐SAFT can describe the solubility of CO₂ in polymers very well. We compare two sets of parameters in the PC‐SAFT equation, Gross et al.'s and Chen et al.'s. As for the swelling ratio, PC‐SAFT using Chen et al. parameters is better than S‐L equation, which is commonly used by early researchers in studying the solubility of CO₂ in polymers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44804.     

Synthesis and Characterization of 1,4‐Dimethyl‐5‐Aminotetrazolium 5‐Nitrotetrazolate

1,4‐Dimethyl‐5‐aminotetrazolium 5‐nitrotetrazolate ( 2 ) was synthesized in high yield from 1,4‐dimethyl‐5‐aminotetrazolium iodide ( 1 ) and silver 5‐nitrotetrazolate. Both new compounds ( 1, 2 ) were characterized using vibrational (IR and Raman) and multinuclear NMR spectroscopy (¹H, ¹³C, ¹⁴N, ¹⁵N), elemental analysis and single crystal X‐ray diffraction. 1,4‐Dimethyl‐5‐aminotetrazolium 5‐nitrotetrazolate ( 2 ) represents the first example of an energetic material which contains both a tetrazole based cation and anion. Compound 2 is hydrolytically stable with a high melting point of 190 °C (decomposition). The impact sensitivity of compound 2 is very low (30 J), it is not sensitive towards friction (>360 N). The molecular structure of 1,4‐dimethyl‐5‐aminotetrazolium iodide ( 1 ) in the crystalline state was determined by X‐ray crystallography: orthorhombic, F_ddd, a=1.3718(1) nm, b=1.4486(1) nm, c=1.6281(1) nm, V=3.2354(5) nm³, Z=16, ρ=1.979 g cm⁻¹, R₁=0.0169 (F>4σ(F)), wR₂ (all data)=0.0352.     

Modeling of CO2 equilibrium solubility in a novel 1‐Diethylamino‐2‐Propanol Solvent

In this work, the equilibrium solubility of CO₂ in a 1‐diethylamino‐2‐propanol (1DEA2P) solution was determined as a function of 1DEA2P concentration (over the range of 1–2 M), temperature (in the range of 298–333 K), and CO₂ partial pressure (in the range of 8–101 kPa). These experimental results were used to fit the present correlation for K₂ (Kent‐Eisenberg model, Austgen model, and Li‐Shen model). It was found that all of the models could represent the CO₂ equilibrium solubility in 1DEA2P solution with ADDs for Kent‐Eisenberg model, Austgen model, and Li‐Shen model of 6.3, 7.3, and 12.2%, respectively. A new K₂ correlation model, the Liu‐Helei model, was also developed to predict the CO₂ equilibrium solubility in 1DEA2P solution with an excellent ADD of 3.4%. In addition, the heat of absorption of CO₂ in 1DEA2P solution estimated by using the Gibbs‐Helmholtz equation was found to be ?45.7 ± 3.7 kJ/mol. Information and guidelines about effectively using data for screened solvents is also provided based on the three absorption parameters: CO₂ equilibrium solubility, second order reaction constant (k₂), and CO₂ absorption heat. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4465–4475, 2017     

Hypercrosslinked silole‐containing microporous organic polymers with N‐functionalized pore surfaces for gas storage and separation

Novel hypercrosslinked microporous organic polymers (MOPs) derived from N‐functionalized siloles as basic building units have been designed and synthesized via Friedel–Crafts alkylation reaction. The resulting N‐functional silole‐containing polymer networks exhibit high thermal stabilities and moderate Brunauer–Emmett–Teller surface area ranging from 666 to 1137 m² g^?1. The incorporation of carbazole or triphenylamine moieties into the polymer skeleton increases the number of electron donating basic nitrogen sites in the porous frameworks. Thus, the corresponding polymer PDMCzS shows enhanced CO₂ adsorption capacities of 3.23 mmol g^?1 at 273 K and 1.13 bar, and higher CO₂/N₂ selectivity (43.99) at 273 K than the analogous silole‐containing polymers P1–P3. These results demonstrated that the N‐functionalized silole‐containing polymer network is a very promising candidate for potential applications in post‐combustion CO₂ capture and sequestration. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45907.     

Synthesis of poly[(2‐oxo‐1,3‐dioxolan‐4‐yl)methyl vinyl ether‐co‐N‐phenylmaleimide] and its miscibility in blends with styrene‐acrylonitrile or poly(vinyl chloride)

The aim of the study was to investigate the synthesis of a copolymer bearing cyclic carbonate and its miscibility with styrene/acrylonitrile copolymer (SAN) or poly(vinyl chloride) (PVC). (2‐Oxo‐1,3‐dioxolan‐4‐yl)methyl vinyl ether (OVE) as a monomer was synthesized from glycidyl vinyl ether and CO₂ using quaternary ammonium chloride salts as catalysts. The highest reaction rate was observed when tetraoctylammonium chloride (TOAC) was used as a catalyst. Even at the atmospheric pressure of CO₂, the yield of OVE using TOAC was above 80% after 6 h of reaction at 80°C. The copolymer of OVE and N‐phenylmaleimide (NPM) was prepared by radical copolymerization and was characterized by FTIR and ¹H‐NMR spectroscopies and differential scanning calorimetry (DSC). The monomer reactivity ratios were given as r₁ (OVE) = 0.53–0.57 and r₂ (NPM) = 2.23–2.24 in the copolymerization of OVE and NPM. The films of poly(OVE‐co‐NPM)/SAN and poly(OVE‐co‐NPM)/PVC blends were cast from N‐dimethylformamide. An optical clarity test and DSC analysis showed that poly(OVE‐co‐NPM)/SAN and poly(OVE‐co‐NPM)/PVC blends were both miscible over the whole composition range. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1809–1815, 2000     

CO2 sorption performance by aminosilane functionalized spheres prepared via co‐condensation and post‐synthesis methods

Amine functionalized silica microspheres were synthesised via a modified Stöber reaction for carbon dioxide (CO₂) adsorption. A number of adsorbents were synthesized by co‐condensation and post synthesis immobilization of amines on porous silica spheres. CO₂ adsorption studies were carried out on a fixed bed gas adsorption rig with online mass spectrometry. Amine co‐condensed silica spheres were found to adsorb up to 66 mg CO₂ g^?1 solid in a 0.15 atm CO₂ stream at 35°C. Simple post‐synthesis addition of aminopropyltriethoxysilane to amine co‐condensed silica was found to significantly increase the uptake of CO₂ to 211 mg CO₂ g^?1 under similar conditions, with CO₂ desorption commencing at temperatures as low as 60°C. The optimum temperature for adsorption was found to be 35°C. This work presents a CO₂ adsorbent prepared via a simple synthesis method, with a high CO₂ adsorption capacity and favorable CO₂ adsorption/desorption performance under simulated flue gas conditions. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2825–2832, 2016     

Copolymerizations of carbon dioxide and epoxides in the presence of rare earth coordinate catalyst

Carbon dioxide (CO₂) as a direct material was copolymerized with epoxides to synthesize new aliphatic polycarbonates, and the copolymerization was catalyzed by the coordinate catalyst composed of rare earth yttrium phosphonate and triisobutylaluminum [Y(P₂₀₄)₃–A1(i‐Bu)₃]. The epoxides used in this research included epichlorohydrin (ECH) and some new glycidol ether (GE) monomers prepared by the reaction of ECH and phenol or alcohol, such as α‐allyl glycidol ether, β‐chloroethyl glycidol ether, benzene glycidol ether, m‐tolyl glycidol ether, and benzyl glycidol ether. The copolymers were characterized by infrared (IR), ¹H nuclear magnetic resonance (‐NMR), and dynamic mechanical analysis. The results show that Y(P₂₀₄)₃–A1(i‐Bu)₃ had better catalytic activity in the copolymerization of CO₂ with epoxide, and the copolymerization rate of aryl GE was distinctly higher than that of aliphatic GE. Dynamic mechanical analysis indicated the glass transition temperature T_g of the copolymers GE–CO₂ were lower than that of ECH–CO₂. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2356–2359, 2003     

Synthesis and CO2 adsorption behavior of amine‐functionalized porous polystyrene adsorbent

A solid amine adsorbent was prepared by modifying a porous polystyrene resin (XAD‐4) with chloroacetyl chloride through a Friedel–Crafts acylation reaction, followed by aminating with tetraethylenepentamine (TEPA). The adsorption behavior of CO₂ from a simulated flue gas on the solid amine adsorbent was evaluated. Factors that could determine the CO₂ adsorption performance of the adsorbents such as amine species, adsorption temperature, and moisture were investigated. The experimental results showed that the solid amine adsorbent modified with TEPA (XAD‐4‐TEPA), which had a longer chain, showed an amine efficiency superior to the other two amine species with shorter chains. The CO₂ adsorption capacity decreased obviously as the temperature increased because the reaction between CO₂ and amine groups was an exothermic reaction, and its adsorption amount reached 1.7 mmol/g at 10 °C in dry conditions. The existence of water could significantly increase the CO₂ adsorption amount of the adsorbent by promoting the chemical adsorption of CO₂ on XAD‐4‐TEPA. The adsorbent kept almost the same adsorption amount after 10 cycles of adsorption–desorption. All of these results indicated that amine‐functionalized XAD‐4 resin was a promising CO₂ adsorbent. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45046.     

Gel Composition and Strength Properties of Alkali‐Activated Oyster Shell‐Volcanic Ash: Effect of Synthesis Conditions

The gel composition and mechanical properties of alkali‐activated oyster shell‐volcanic ash were investigated at different NaOH concentrations (8, 12, and 15M) and curing temperatures (60°C and 80°C) in wet and dry conditions. XRD, FTIR, SEM‐EDS, and TGA‐DSC were used for microstructural characterization of the binder. The gel composition of the system was found to be influenced by NaOH concentration and was not affected when curing temperature was varied from 60°C to 80°C. The main phase was N,C–A–S–H for all alkali‐activated oyster shell‐volcanic ash, with C–S–H as secondary phase for some samples and contains high percentage of iron. The splitting at υ₃ = 1400–1494 cm^?1 on FTIR spectra corresponded to the elimination of the degeneracy due to the distortion of CO₃^2? group. The high degree of splitting indicated that this carbonate group is linked to Ca²⁺. The compressive strength was influenced by curing temperature and the formation of a secondary phase. The compressive strength in dry condition increased roughly between 28 and 180 d for some samples, while in wet condition, the partial dissolution of Si–O–Si bonds of some silicate phases resulted in a reduction of strength.     

In situ carbon deposition in polyetherimide/SAPO‐34 mixed matrix membrane for efficient CO2/CH4 separation

A simple method of pore modification complied with defect removal polymer zeolite mixed matrix membrane was developed by in situ carbon (C) deposition. The C deposition was achieved by the controlled decomposition of polymer matrix by heat treatment. In this study, polyetherimide/silicoaluminophosphate‐34 mixed matrix membrane (MMM) was fabricated on clay‐alumina support tube, followed by carbonization of the polymer matrix for gas separation application. MMM without heat treatment were also synthesized for comparison by conventional method. The membranes were characterized by X‐ray diffraction, field emission scanning electron microscopy, and X‐ray photoelectron spectroscopy. Due to carbonization, in situ C nanoparticles were deposited in to the interfacial pores, and filler particles were oriented in preferable direction. The presence of C?O, C? N, and graphitic carbon in the matrix, may be an indication of partial carbonization and restoration of adherence of polymer with substrate. The separation factor for CO₂/CH₄ achieved 39.15 with a permeance value of 23.01 × 10^?8mol/(m² s Pa) for CO₂ at 30 °C and 200 kPa feed pressure. For the first time, this work shows an improvement toward permeability of MMM by simple carbonization of polymer matrix with commendable values as compare to the reported literature. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45508.     

Vapour–liquid equilibrium of CO2 in aqueous solutions of N‐methyl‐2‐ethanolamine

The equilibrium solubility of CO₂ into aqueous solution of sterically hindered N‐methyl‐2‐ethanolamine or methyl amino ethanol (MAE) was investigated in the temperature range of 303.1–323.1 K and total CO₂ pressure in the range of 1–350 kPa. The N‐methyl‐2‐ethanolamine aqueous solutions studied were 0.968, 1.574, 2.240 and 3.125 mol kg^?1 of solvent. © 2011 Canadian Society for Chemical Engineering