FUEL
·
2019
·
IF 5.128
Yu Wu,Hong Du,Yajun Gao,Xiaoyao Liu,Tingyu Yang,Long Zhao,Xiaoqing Yue,Shuai Zhang,Jianbin Zhang
As one of the most important approaches to reduce CO 2 emission from various combustion processes, CO 2 adsorption capture is facing several many challenges, including high adsorbent cost, high energy cost, and low CO 2 selectivity. In this work, four novel silicate-based nanomaterials (SBNMs), including magnesium silicate (MgSiO 3 ), manganese silicate (MnSiO 3 ), copper silicate (CuSiO 3 ) and zirconium silicate (ZrSiO 4 ), were fabricated via hydrothermal method with SiO 3 2− extracted from coal gangue (CG) for the adsorption capture of CO 2 . Under the optimum conditions, the SiO 3 2− extraction ratio from the CG reached to 77.69%. The extracted SiO 3 2− was used to synthesize SBNMs with high surface area and high thermal stability, which were characterized with Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and nitrogen adsorption/desorption isotherms technologies. These as-obtained SBNMs exhibited CO 2 adsorption capability of (7.82–17.93) cm 3 /g at 25 °C under 1 atm, respectively. The CO 2 adsorption data were successfully fitted with Freundlich model, and the adsorption processes were obvious chemically favored, spontaneous and exothermic according to thermodynamic parameters, including Q st , Δ G ads , Δ H ads and Δ S ads . Significantly, all SBNMs showed a excellent cycle performance and strong selectivity toward CO 2 over N 2 . The aim of this work is to provide a new method of utilization of coal gangue waste and a low-cost, and highly selective CO 2 adsorbents.
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ENVIRONMENTAL SCIENCE & TECHNOLOGY
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2018
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IF 6.653
Shihan Zhang,Yao Shen,Peijing Shao,Jianmeng Chen,Lidong Wang
The main issue related to the deployment of the amine-based absorption process for CO2 capture from flue gas is its intensive energy penalty. Therefore, this study screened a novel biphasic solvent, comprising a primary amine e.g., triethylenetetramine (TETA) and a tertiary amine e.g., N,N-dimethylcyclohexylamine (DMCA), to reduce the energy consumption. The TETA-DMCA blend exhibited high cyclic capacity of CO2 absorption, favorable phase separation behavior, and low regeneration heat. Kinetic analysis showed that the gas- and liquid-side mass transfer resistances were comparable in the lean solution of TETA-DMCA at 40 °C, whereas the liquid-side mass transfer resistance became dominant in the rich solution. The rate of CO2 absorption into TETA-DMCA (4 M, 1:3) solution was comparable to 5 M benchmark monoethanolamine (MEA) solution. Based on a preliminary estimation, the regeneration heat with TETA-DMCA could be reduced by approximately 40% compared with that of MEA. 13C NMR analysis revealed that the CO2 absorption into TETA-DMCA was initiated by the reaction between CO2 and TETA via the zwitterion mechanism, and DMCA served as a CO2 sinker to regenerate TETA, resulting in the transfer of DMCA from the upper to lower phase. The proposed TETA-DMCA solvent may be a suitable candidate for CO2 capture.
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Journal of CO2 Utilization
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2018
·
IF 5.503
Keng Xuan,Yanfeng Pu,Feng Li,Aixue Li,Jing Luo,Lei Li,Feng Wang,Ning Zhao,Fukui Xiao
A series of trifluoroacetic acid (TFA) modulated metal-organic frameworks UiO-66 catalysts were synthesized for the direct synthesis of dimethyl carbonate (DMC) from CO 2 and methanol in this work. Characterization results show that the surface area, pore size, pore volume as well as the amount of missing-linker defects, Lewis acid site, Lewis basic site and hydroxyl of UiO-66-X can be tuned by regulating the amount of TFA modulator. Catalytic activity assessments reveal that TFA modulation enhanced the activity of UiO-66-X. The catalytic activity improvement of the UiO-66-X could be attributed to the increased amount of active sites and the enlargement of porosity originated from TFA modulation. Moreover, a possible reaction mechanism for DMC synthesis from CO 2 and methanol over UiO-66-X was proposed based on the in situ FT-IR results.
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International Journal of Greenhouse Gas Control
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2018
·
IF 4.078
Yanru Chen,Wusan Jiang,Xiao Luo,Yangqiang Huang,Bo Jin,Hongxia Gao,Wensheng Li,Zhiwu Liang
In this work, the stopped-flow technique is used to determine the kinetics data in terms of pseudo first-order rate constants ( k 0 ) for the homogenous reaction of CO 2 into aqueous solutions of 3-dimethylaminopropylamine (DMAPA) and 3-diethylaminopropylamine (DEAPA) as amine concentrations ranged from 0.05 kmol/m 3 to 0.15 kmol/m 3 and temperature ranged from 293 K to 313 K. It is found that k 0 increased with increasing temperature and with increasing amine concentration. The mechanism of the pseudo first-order chemical reaction hypothesis is applied to interpret the experimental data. The Arrhenius expressions as k 2 = 8.69 × 10 9 × exp ( − 4226.2 / T ) for DMAPA and k 2 = 7.21 × 10 12 × exp ( − 6162.9 / T ) for DEAPA are obtained. The results show that the experimental CO 2 absorption rates exhibited good agreement with predicted CO 2 absorption rates with an average relative deviation (ARD) of 2.34% and 7.53%, respectively. Finally, the interaction of tertiary amine groups with primary amine groups and the effect of molecular structure on the interaction are discussed by comparing the CO 2 absorption and desorption performances in five different systems (MEA, DEEA, MEA + DEEA, DMAPA, DEAPA). It is found that the intermolecular interaction of amino groups is stronger than that of intramolecular interaction.
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RSC Advances
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2018
·Vol. 8
·期 17
·9192-9201
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IF 2.936
Chao Feng,Xianglei Cao,Liugen Zhang,Changyan Guo,Naeem Akram,Jide Wang
Development of heterogeneous catalysts for the cycloaddition of CO2 with epoxides to produce cyclic carbonates is a hot issue in the field of chemical fixation of carbon dioxide. It is fairly promising as production of by-products is quite low. In this study, the [Zn3(BTC)2]/n-Bu4NBr catalytic system was investigated for the solventless cycloaddition of carbon dioxide with epoxides and had an excellent synergetic effect in promoting the reaction. The reaction parameters were moderate i.e. (130 °C and 13 bar CO2 pressure) and were selected by a study of the catalytic system. Under the optimal reaction conditions, the yield of cyclic carbonate reached 99%. A decrease in the yield of cyclic carbonate was not apparent after [Zn3(BTC)2] was reused three times, indicating that [Zn3(BTC)2] was stable. At the same time, the catalytic activity of the catalyst for other epoxides was also verified. The acidic and alkaline nature of the [Zn3(BTC)2] catalyst did not change obviously after recycling the catalyst three times. In this study it is also verified that the [Zn3(BTC)2] catalytic cycloaddition reaction was closely related to the Lewis acid/base distribution. In addition, a plausible mechanism for the synergistic effect of the catalyst (Lewis acid and base properties) and the co-catalyst was suggested.
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AICHE JOURNAL
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2018
·Vol. 64
·期 7
·2515-2525
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IF 3.326
Helei Liu,Moxia Li,Xiao Luo,Zhiwu Liang,Raphael Idem,Paitoon Tontiwachwuthikul
In this work, Diethanolamine (DEA) was considered as an activator to enhance the CO 2 capture performance of Monoethanolamine (MEA). The addition of DEA into MEA system was expected to improve disadvantages of MEA on regeneration heat, degradation, and corrosivity. To understand the reaction mechanism of blended MEA-DEA solvent and CO 2 , 13 C nuclear magnetic resonance (NMR) technique was used to study the ions (MEACOO - , DEACOO – , MEA, DEA, MEAH + , DEAH + , , ) speciation in the blended MEA-DEA-CO 2 -H 2 O systems with CO 2 loading range from 0 to 0.7 mol CO 2 /mol amine at the temperature of 301 K. The different ratios of MEA and DEA (MEA: DEA = 2.0:0, 1.5:0.5, 1.0:1.0, and 0:2.0) were studied to comprehensively investigate the role of DEA in the system of MEA-DEA-CO 2 -H 2 O. The results revealed that DEA performs the coordinative role at the low CO 2 loading and the competitive role at high CO 2 loading. Additionally, the mechanism was also proposed to interpret the reaction process of the blended solvent with CO 2 . © 2018 American Institute of Chemical Engineers AIChE J , 64: 2515–2525, 2018
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Environmental Progress & Sustainable Energy
·
2018
·Vol. 37
·期 6
·2026-2033
·
IF 1.326
Ke Wang,Ji Sun,Pengfei Zhao
The development of novel Li 4 SiO 4 -based sorbents is hampered by a lack of understanding of the mechanisms governing CO 2 adsorption on the Li 4 SiO 4 surface. In this work, the adsorption of CO 2 and flue gas components (such as H 2 O and SO X (SO 2 and SO 3 )) on a simulated Li 4 SiO 4 surface was investigated using ab initio-based energetic calculations. The Li 4 SiO 4 surface was modeled by a cluster of lithium silicate, in which the atoms were unsaturated to simulate the active sites. Furthermore, Fourier transform infrared (FTIR) spectra were also analyzed. The calculated results showed that three possible configurations were determined: CO 2 weakly sorbed on the oxygen sites of Li 4 SiO 4 through physisorption; a carbonate species appeared, which was characterized by chemisorption; and a linear cluster of Li + -O = C=O formed, having the largest sorption energy. These three possible pathways were likewise in accordance with the FTIR results. Moreover, a pre-chemisorption of water on Li 4 SiO 4 resulted in promoted CO 2 capture, while the presence of competitive SO X sorption on the same active sites as CO 2 sorption showed an inhibition effect. The results clarify the complex adsorption mechanisms on the Li 4 SiO 4 surface. © 2018 American Institute of Chemical Engineers Environ Prog, 37: 1901–1907, 2018
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Analytical Methods
·
2018
·Vol. 10
·期 25
·2989-2993
·
IF 2.073
Bingyan Han,Ying Li,Tingting Peng,Mingbo Yu,Xixi Hu,Gaohong He
In this paper, polyethyleneimine (PEI) was applied as a carbon source for synthesizing fluorescent carbon dots (CDs) through a facile and one-step hydrothermal route. Both the N-doping and the amino-functionalization of CDs were accomplished simultaneously. The CDs exhibited strong blue fluorescence and good dispersion in aqueous solution. A large number of amino groups on the surface of CDs greatly simplified the subsequent modification steps. Through an amide reaction, glutathione-functionalized CDs were successfully applied to the selective detection of Co2+, in the linear range from 2.0 × 10−5 to 1.0 × 10−4 mol L−1.
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Nano Research
·
2018
·Vol. 11
·期 5
·2450-2459
·
IF 7.994
Zhang Bing,Zhao Tian-Jian,Feng Wei-Jie,Liu Yong-Xing,Wang Hong-Hui,Su Hui,Lv Li-Bing,Li Xin-Hao,Chen Jie-Sheng
The greenhouse effect and global warming are serious problems because the increasing global demand for fossil fuels has led to a rapid rise in greenhouse gas exhaust emissions in the atmosphere and disruptive changes in climate. As a major contributor, CO 2 has attracted much attention from scientists, who have attempted to convert it into useful products by electrochemical or photoelectrochemical reduction methods. Facile design of efficient but inexpensive and abundant catalysts to convert CO 2 into fuels or valuable chemical products is essential for materials chemistry and catalysis in addressing global climate change as well as the energy crisis. Herein, we show that two-dimensional fewlayer graphitic carbon nitride (g-C 3 N 4 ) can function as an efficient metal-free electrocatalyst for selective reduction of CO 2 to CO at low overpotentials with a high Faradaic efficiency of ~ 80%. The polarized surface of ultrathin g-C 3 N 4 layers (thickness: ~ 1 nm), with a more reductive conduction band, yields excellent electrochemical activity for CO 2 reduction.
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JOURNAL OF MEMBRANE SCIENCE
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2018
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IF 6.578
Xinru Zhang,Tao Zhang,Yonghong Wang,Jinping Li,Chengcen Liu,Nanwen Li,Jiayou Liao
Mixed-matrix membranes (MMMs) for CO 2 /N 2 separation were prepared by incorporating nickel-substituted ZIF-8 (Zn/Ni-ZIF-8) into a polyether-block-amide (PEBA2533) polymer, in which the Zn and Ni ions in Zn/Ni-ZIF-8 have different affinities for CO 2 based on π-complexation; these MMMs exhibited exceptional molecular sieving properties compared to ZIF-8-PEBA MMMs. Scanning electron microscopy revealed that Zn/Ni-ZIF-8 nanoparticles were small and uniformly distributed within the PEBA, and attenuated total reflectance Fourier-transform infrared spectroscopy revealed good interfacial compatibility between the Zn/Ni-ZIF-8 and PEBA; consequently these MMMs exhibited excellent mechanical properties . The 10% Zn/Ni-ZIF-8-PEBA MMM showed a high CO 2 permeability of 321 Barrer, and a CO 2 /N 2 selectivity of 42.8 at 2 bar; these values were much higher than those of the 10% ZIF-8-PEBA MMM (266 Barrer and 33.8, respectively). We assume that different metal-ion affinities towards CO 2 resulted in the asymmetric adsorption/desorption behaviour of these MMMs, which led to a significantly higher permselectivity for the Zn/Ni-ZIF-8-PEBA MMM. The MMM loaded with 10% Zn/Ni-ZIF-8 exhibited long-term CO 2 -separation-performance stability under mixed-gas conditions, with a CO 2 permeability of 282 Barrer and a CO 2 /N 2 selectivity of 42.7. Moreover, the permselectivity of the 10% Zn/Ni-ZIF-8-PEBA MMM under pure-gas condition surpassed Robeson's upper bound reported in 2008.
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JOURNAL OF MOLECULAR LIQUIDS
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2018
·
IF 4.513
Mingwei Zhao,Haonan He,Caili Dai,Xuepeng Wu,Yue Zhang,Yongping Huang,Chenglin Gu
This study presents the synthesis of a CO 2 -responsive surfactant namely 2‑alkyl‑1‑hydroxyethyl imidazoline (HEA n IBs n = 16, 18, 20), which exhibits satisfactory surface and adsorption properties. The micelle formation and adsorption of the above imidazoline based surfactant in aqueous solution were studied in this work. CMC , the effectiveness of surface tension reduction, the maximum surface excess concentration, the minimum area occupied per surfactant molecule at the air/water interface, and the micelle aggregation number were obtained by measuring surface tension. Dynamic light scattering indicates that when the surfactant concentration is 1.2 times the CMC, the hydrodynamic radii of the three surfactants studied were almost equal to 8 nm. Electrical conductivity measurements indicate the micellization of surfactants in aqueous solution. In addition, typical thermodynamic parameters, including Δ G m 0 , Δ G ads 0 , Δ H m 0 , Δ S m 0 , Δ H m A , Δ S m A , and Δ C p, m 0 were evaluated. The thermodynamic parameters show that micelle formation is entropy-and-enthalpy co-driven from 298 K to 318 K. We expect to elucidate the self-assembly of CO 2 -responsive surfactant in an aqueous solution.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2018
·
IF 5.091
Huang Ouyang,Li Guo,Cao Li,Xueqin Chen,Bingbing Jiang
Advanced porous organic materials with high gas storage capacity and high selectivity have been rapidly developed for CO 2 adsorbents in the recent decade, due to extremely high surface area and nanoscale pore size. Here, novel amino acids-incorporated solid adsorbents based on porous hypercrosslinked polymers were fabricated by a dispersion polymerization of an aromatic monomer and quaternary ammonium salt comonomer, subsequently a hypercrosslinked reaction and an ion-exchange step. The developed adsorbents presented mesopores structure with BET surface area up to 864 m 2 /g and an extremely high CO 2 capturing capacity up to 60.7 wt% (13.8 mmol/g) at 273 K/1 bar. The results also showed the adsorbent had an excellent recycling ability over repetitive adsorption-desorption cycles. All the results suggest that the amino acids-modified porous sorbents are promising CO 2 sorbents that can meet the challenges of the current CO 2 capture and storage technology.
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