ChemCatChem
·
2019
·Vol. 11
·期 16
·3919-3926
·
IF 4.495
Ke Liu,Zhenbo Zhao,Weiwei Lin,Qiang Liu,Qifan Wu,Ruhui Shi,Chao Zhang,Haiyang Cheng,Masahiko Arai,Fengyu Zhao
Graphical Another drop of copper : A non-noble metal catalyst of Cu/TiO 2 is effective for the heterogeneous N -methylation of N -methylaniline with CO 2 and H 2 , in which CHO* is formed as methyl reagent, and it reacts with N -methylaniline to produce intermediate N -methylformanilide followed by its hydrogenation to N,N -dimethylaniline. A non-noble heterogeneous catalyst of Cu/TiO 2 was prepared for N -methylation of N -methylaniline (MA) with CO 2 and H 2 . 5 wt.–% Cu loaded TiO 2 (P25) catalyst exhibited a high performance, with 82 % MA conversion and 98 % N,N -dimethylaniline (DMA) selectivity under the reaction conditions used (4 MPa H 2 , 2 MPa CO 2 , 180 °C, 36 h). The Cu/TiO 2 catalyst was more effective with respective to the total conversion and the DMA selectivity as compared to 5 wt.–% Cu loaded catalysts on CeO 2 , ZnO and activated carbon materials. The possible active species of Cu/TiO 2 catalyst should be both Cu + and Cu 0 which contributed to the high activity as the reaction conversion increased linearly with them exposed on the surface of catalyst. Moreover, the reaction pathways involved were studied; it was likely that the reaction took place via an intermediate of formaldehyde that was formed from CO 2 and H 2 , as confirmed by in situ diffuse reflectance Fourier-transform infrared spectroscopy, then it reacted with MA to give N -methylformanilide (MFA), and finally MFA was hydrogenated to DMA.
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高影响因子
Solar RRL
·
2018
·Vol. 3
·期 2
·1800274
·
IF 0
Like Huang,Shixiao Bu,Danli Zhang,Ruixiang Peng,Qiang Wei,Ziyi Ge,Jianjun Zhang
Electron transport layer (ETL)-free perovskite solar cells (PSCs) are getting much more attention with their simpler structure and potentially low cost as well as higher stability. However, the elimination of ETL (such as TiO 2 ) with intrinsically deep valance band level leads to the absence of the hole blocking mechanism and thus serious charge recombination at the FTO/perovskite interface compared with ETL-based devices. An interface band bending associated built-in electric field is an essential driving force of charge separation. Here, by intentional polarity tailoring of perovskite via incorporation of Sb as a shallow donor, ETL-free PSCs with optimized energy level alignment both at the front and rear interfaces are constructed, resulting in an enhanced built-in electric field and thus efficient majority carrier collection and minority blocking as well as reduced interfacial charge recombination at both interfaces. Device simulation calculations also confirm the importance of polarity control for device performance improvement. The effect of doping on the perovskite films properties and device performance are systematically demonstrated. Correspondingly, ETL-free PSCs with a champion power conversion efficiency of 12.62% is achieved.
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GREEN CHEMISTRY
·
2018
·Vol. 21
·期 3
·567-577
·
IF 8.586
Wenfeng Zhao,Xiaoping Chi,Hu Li,Jian He,Jingxuan Long,Yufei Xu,Song Yang
Catalytic fixation of CO2 to produce valuable fine chemicals is of great significance to develop a green and sustainable circulation of excessive carbon in the environment. Herein, a series of non-toxic, biodegradable and recyclable acetylcholine-carboxylate bio-ionic liquids with different cations and anions were simply synthesized for producing formamides and methylamines using atmospheric CO2 as a carbon source, and phenylsilane as a hydrogen donor. The selectivity toward products was tuned by altering the reaction temperature under solvent or solvent-free conditions. N-Methylamines (ca. 96% yield) were obtained in acetonitrile at 50 °C, while N-formamides (ca. 99% yield) were attained without a solvent at 30 °C. The established bio-ionic liquid catalytic system found a wide range of applicability in substrates and possessed a high potentiality in scale-up to gram-grade production. The developed catalytic system was fairly stable, which could be easily reused without an apparent loss of reactivity, possibly due to the strong electrostatic interactions between the cation and anion. The combination of experimental and computational results explicitly elucidated the reaction mechanism: PhSiH3 activated by a bio-IL was favorable for the formation of silyl formate from hydrosilylation of CO2, followed by a reaction with an amine to give an N-formamide, while an N-methylamine was formed by further hydrosilylation of the N-formamide.
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高影响因子
POLYMER SCIENCE SERIES B
·
2018
·Vol. 60
·期 5
·578-588
·
IF 0.735
Shang Jiaojiao,Lan Jianwu,Yao Guo,Yan Bin,Guo Ronghui,Zheng Wei,Gu Long
A series of poly(ester-imide-ether), consisting of soft segments from poly(tetramethylene glycol) and N,N ′-bis(2-carboxyethyl) pyromellitimide and hard segments based on 1,4-butanediol and N,N ′-bis(2-carboxyethyl) pyromellitimide, were synthesized via the melt polycondensation. The chemical structures of the prepared elastomers were confirmed by Fourier transform infrared spectroscopy and 1 HNMR, respectively. The results indicated that the introduction of aromatic bisimide groups endows the elastomers with excellent thermal stability and mechanical property, which increase with the increment of imide unit content in the prepared elastomers. Additionally, compared to the poly(ester-ether) elastomer, these poly(esterimide-ether) fibers displayed stronger tensile strength and better low-temperature elastic recovery property.
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POLYMER
·
2018
·
IF 3.483
Qijing Chen,Fei Han,Chao Lin,Xuejun Wen,Peng Zhao
The aim of this study is to synthesize well-defined bioreducible core crosslinked star (CCS) polymers via heterogeneous reversible addition-fragmentation transfer (RAFT) polymerization in aqueous ethanol solutions. To this end, water-soluble linear arm polymers, poly (poly (ethylene glycol) methyl ether methacrylate) (PPEGMA), poly (2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly ( N , N -dimethylacrylamide) (PDMA), were prepared respectively. Next, heterogenous RAFT polymerization of the polymers with N , N ′-bis(acryloyl)cystamine (BAC) as a crosslinker was systemically investigated in an aqueous ethanol solvent. It was found that these bioreducible CCS polymers with crosslinked BAC core could be prepared successfully depending on polymerization parameters. The formation of PPEGMA-based CCS polymers was affected by water volume fraction ( V w ) of water-ethanol solution, reaction time, arm polymer concentration, and spacing monomer . Besides, at an optimal V w of 80% ( i . e . the molar concentration of water is 44.44 M) and arm polymer concentration of 10% (w/v), PPEGMA-based CCS polymers at >90% yield could be achieved within 1 h. By the same V w and reaction time, PDMAEMA- and PDMA-based CCS polymers could also be prepared with high yield (>75%). The mechanism underlying the formation of the CCS polymers was ascribed to enhanced driving force of polymerization-induced self-assembly at an optimal V w . These CCS polymers were degradable in thiol-containing dithiothreitol, suggesting their potential application for drug release in a reductive intracellular environment.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2012
·
IF 1.693
Dongbei Shao,Xiaoxing Lu,Wenjun Fang,Yongsheng Guo,Li Xu
A novel ionic liquid N-ethyl piperazinium propionate, [NEPP], was prepared, and the densities and viscosities for the binary mixtures of [NEPP] with methanol, ethanol, n-propanol, and n-butanol were measured over the whole concentration range at (298.15, 303.15, 308.15, and 313.15) K and 0.1 MPa. The data of the excess molar volume, VmE, were calculated and fitted with the Redlich–Kister type polynomial equation. The values of VmE of the investigated systems are all negative, indicating that the ion–dipole interactions play important roles between the molecules of the ionic liquid and the alcohols.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2016
·
IF 3.299
Shiyu Zhang,Yun Zou,Tengyou Wei,Chunxia Mu,Xiangjun Liu,Zhangfa Tong
The blended membranes of polyvinyl alcohol (PVA) and chitosan (CS) (PVA-CS) were prepared for pervaporation dehydration of a binary system of n -butyl acetate/water and a ternary mixture of n -butyl acetate/ n -butanol/water. Membranes were characterized by FTIR, DSC and XRD to investigate the intermolecular interactions, the blending compatibility and the effects of blending on crystallinity. Tensile strengths were measured to determine the influence of blending ratios on the membrane’s mechanical properties. The membrane’s degree of swelling in water dropped significantly with increasing CS fraction. The results agreed well with the calculation of the solubility parameter. Separation factor and permeation flux increased when the temperature was raised for both the binary and ternary pervaporation systems. An optimal separation factor of 27,000 with a total flux of 402 g·m −2 ·h −1 was obtained using the blend membrane containing 25 wt% CS at 40 °C for the binary system. For the ternary system, the maximum separation factor and total flux were obtained for blend membranes at 75 wt% and 50 wt% CS content, respectively.
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CHINESE JOURNAL OF POLYMER SCIENCE
·
2015
·Vol. 33
·期 11
·1491-1502
·
IF 1.835
Fang Li-feng,Wang Na-chuan,Zhou Ming-yong,Zhu Bao-ku,Zhu Li-ping,John Angelin Ebanezar
To functionalize poly(vinyl chloride) (PVC) for various applications, monomers containing tertiary amine group are incorporated into PVC via atom transfer radical polymerization (ATRP) initiated by the labile chlorines in their backbones. The kinetics of synthesis was carefully investigated, and it is proven that the grafting polymerization process can be effectively controlled by regulating the reaction time. The membranes are fabricated using PVC and copolymers by non-solvent induced phase separation (NIPS) process. The hydrophilicity and pore structure of copolymer membranes were enhanced as well, these membranes are endowed with positive charge. When PDMA% ( i.e. , the PDMA weight percentage in copolymer) is 31.1%, the flux and Victoria blue B rejection are 26.0 L·m -2 ·h -1 (0.5 MPa) and 91.2%, respectively. Thus, the newly synthesized polymer is proven to be a promising material for dye separation with positive charges.
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高影响因子
HIGH PERFORMANCE POLYMERS
·
2015
·
IF 1.286
Qiuxiang Wu,Zhizhou Yang,Jinshui Yao,Donghong Yu
Five new optically active poly(amide–imide)s (PAIs) (PAI3a–PAI3e) were synthesized through the direct polycondensation reaction between chiral N,N′-(pyromellitoyl)-bis-l-amino acids and 4,4′-diaminodiphenyl ether. The resulted polymers were fully characterized by means of Fourier transform infrared (FTIR) and proton nuclear magnetic resonance spectroscopy, elemental analysis, inherent viscosity measurement, solubility tests, specific rotation, and thermogravimetric analysis (TGA). The biodegradation studies of the PAIs were performed in soil and in phosphate buffer solution. The surface morphology and hydrophobicity of the biodegraded PAI films were investigated. FTIR spectra showed structural changes on PAI powders being treated in phosphate buffer solution. The TGA data showed that the thermal stability of PAI powders decreased with the degradation time. The collected degradation products were soluble in water and had absorption in ultraviolet and visible light region. Possible biodegradation mechanism of amino acid-based PAIs was explored.
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ENERGY & FUELS
·
2024
·
IF 5.2
Dong Wang,Malcolm A. Kelland,Ying Xu,Xin Wang,Ping Lu,Jian Dong
Rapid formation of natural gas clathrate hydrates has been a significant hazard in off-shore natural gas drilling and gas transport. During operation, polymer inhibitors can serve as low-dosage kinetic inhibitors to prevent the formation of gas hydrates. A comprehensive consideration of the multiple factors involved in the actions of kinetic hydrate inhibitors (KHIs) can elucidate the inhibiting behavior of polymers. Here, amphiphilic poly(N-isopropylmethacrylamide) (PNIPMAm) (or poly(N-isopropylacrylamide)) are found to achieve weak to strong inhibition by the variable superimposed effect of the polymer’s amide group and hydrophobic effect of the polymer’s alkyl groups on the aqueous phase. The interfacial and bulk water mobility and hydrogen bonding energy in the polymer solutions are compared by low-temperature nuclear magnetic resonance (NMR) relaxometry. The mobility of the water is found to be sensitive to the hydrophobic α-methyl side group in PNIPMAm and its molecular weight when a guest molecule tetrahydrofuran is present. The water hydrogen bonding energies measured from NMR are also associated with the nonfreezable bound water amount revealed by differential scanning calorimetry. The α-methyl side group leads to a significant reduction of the water mobility, an increase in the hydrogen bonding energies of the interfacial water, and a decrease of the hydrate growth rate constants by 2 to 3 orders of magnitude. The retarded reaction kinetics of heterogeneous hydrate growth can be related to the hydrophobic effect of the polymer’s α-methyl side group and bound water properties (mobility and amount) in the interface.
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ATMOSPHERIC ENVIRONMENT
·
2024
·
IF 4.2
Cici Fan,Huijie Yan,Weigang Wang,Zheng Sun,Maofa Ge
Aldehydes are one of the most important oxygenated volatile organic compounds in the atmosphere, contributing to atmospheric radicals such as HO 2 and RO 2 , which play a pivotal role in atmospheric chemistry and the oxidative capacity of the atmosphere. The kinetics, gas-phase products, and SOA formation of pentanal and n-hexanal initiated by Br atoms were studied in this work. The reaction rate constants of n-pentanal and n-hexanal reacting with Br atoms were determined to be (1.77 ± 0.25) × 10 −11 cm 3 molecule −1 s −1 and (2.07 ± 0.29) × 10 −11 cm 3 molecule −1 s −1 at 298 K and 760 Torr, respectively. Key gas-phase products, including smaller aldehydes, carboxylic acids, and alcohols, are known to contribute to atmospheric reactivity and have potential implications for air quality by promoting the formation of secondary pollutants and influencing the oxidative capacity of the atmosphere. The SOA yields were (5.24 ± 0.10)% and (6.00 ± 1.20)% for n-pentanal and n-hexanal, respectively, higher than the SOA yields of the aldehydes reaction initiated by OH radicals. The higher SOA yields observed from Br atoms oxidation compared to OH radical oxidation highlight the necessity to re-evaluate the role of halogen chemistry in atmospheric processes, particularly in regions where halogen compounds are prevalent. This research enhances our understanding of the atmospheric fate of aldehydes and highlights the importance of considering halogen-driven oxidation pathways in atmospheric models.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Quanzhi Zhang,Tianlin Zhou,Xinchun Ye,Zhi-Xia Zhang,Shaolin Wu,Dezhi Chen
Persulfate-based advanced oxidation process dominated by singlet oxygen ( 1 O 2 ) shows potential for targeted degradation of organic pollutants but the regulation of 1 O 2 generation is still challenging. In this study, N-doped carbon polyhedron-modified Co@N-doped carbon nanotube (NCP/Co@NCNT) were successfully fabricated. The as-obtained NCP/Co@NCNT demonstrated a much enhanced 1 O 2 production in activating peroxymonosulfate (PMS) because of the nanoconfinement effect of metallic Co nanoparticles encapsulated in NCNT, which was further confirmed by density functional theory calculations. The NCP/Co@NCNT/PMS system has excellent catalytic performance and is capable of removing 97 % of carbamazepine (CBZ) in 55 min (Catalyst: 0.1 g/L, CBZ: 20 mg/L, PMS: 0.5 g/L). Quantitative structure–activity relationship (QSAR) analysis uncovered a positive correlation between the oxidation kinetics of organic pollutants and their E HOMO . Specifically, pollutants with higher E HOMO are more easily oxidized in the 1 O 2 -dominated NCP/Co@NCNT/PMS system. Furthermore, the generated intermediates exhibited low toxicity in the system with 1 O 2 as the primary active species. This study offers an effective approach to prepare catalysts for the selective elimination of organic micropollutants in complex water environments.
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