BIOMASS & BIOENERGY
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2018
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IF 3.358
Jiaxiong Liu,Yajin Li,Huimin Liu,Dehua He
Ce 1-x Zr x O 2 (0 ≤ x ≤ 0.2) solid solutions were prepared by hydrothermal method and applied for the synthesis of glycerol carbonate from glycerol and CO 2 in the presence of 2-cyanopyridine (dehydrant) with dimethyl formamide (DMF) as a solvent. The physicochemical properties of the catalysts were characterized by ICP, XRD , BET, H 2 -TPR, CO 2 /NH 3 -TPD, TEM and XPS . The activation route of CO 2 and glycerol were measured by DRIFTS and FT-IR. Compared to pure CeO 2 , Ce 1-x Zr x O 2 solid solutions exhibited enhanced activity in the present reaction system, and the improved catalytic activity was associated with the BET surface area and the acid-base properties. DRIFTS results showed that the chelating bidentate carbonate species was the main adsorption pattern for CeO 2 and no striking differences between Ce 0·98 Zr 0·02 O 2 and CeO 2 . FT-IR spectra of the spent catalysts revealed that glycerol and 2-cyanopyridine could be activated on CeO 2 -based catalysts, and an ester intermediate was formed for the production of glycerol carbonate. Thus, a plausible mechanism is proposed for the synthesis of glycerol carbonate from glycerol and CO 2 in the presence of 2-cyanopyridine in DMF solvent over CeO 2 -based catalysts. Moreover, the recyclability of Ce 0·98 Zr 0·02 O 2 was measured and the catalysts could be regenerated through a simple calcination process at 400 °C for 5 h in air.
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JOURNAL OF CHEMICAL THERMODYNAMICS
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2018
·
IF 2.631
Xue Wang,Dawei Shang,Shaojuan Zeng,Yuanming Wang,Xiaochun Zhang,Xiangping Zhang,Jindun Liu
Absorption and adsorption technology as widely used methods have been reported for carbon dioxide (CO 2 ) separation. In order to combine the advantages of absorption and adsorption methods, ionic liquids (ILs) as absorption function and zeolitic imidazolate framework-8 (ZIF-8) as adsorption function were integrated into a slurry to efficiently capture CO 2 by the absorption-adsorption method. In this study, two pyridinium-based ILs, [C 4 Py][NTf 2 ] and [C 4 Py][N(CN) 2 ] were synthesized, and mixed with different concentration of ZIF-8 to form hybrid slurries. CO 2 solubility in the different hybrid slurries at temperatures from 303.15 to 333.15 K was measured. The results indicated that CO 2 solubility increases significantly with increasing pressure and decreases with increasing temperature. Moreover, CO 2 solubility increases with the increase of ZIF-8 content, indicating that the addition of ZIF-8 into ILs can obviously enhance CO 2 solubility. CO 2 solubility in the ZIF-8/[C 4 Py][NTf 2 ] slurry increases by 24% compared with the corresponding pure IL at 303.15 K and 1.80 MPa. The absorption-adsorption mechanism was studied using FT-IR and NMR spectroscopy. It was demonstrated that CO 2 absorption and adsorption in the ZIF-8/ILs hybrid slurries is a physical process. Furthermore, the ZIF-8/[C 4 Py][NTf 2 ] slurry can also keep the stable absorption performance after five consecutive absorption and desorption cycles. Considering the excellent capacity, thermal stability and recyclability, the porous materials/ILs slurry will provide new insight to CO 2 capture compared with the conventional absorbents.
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RSC Advances
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2015
·Vol. 5
·期 86
·70101-70108
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IF 3.84
Qiong Wu,Jun Shi,Jing Wei,Liu Yang,Shaokui Cao
In this work, aliphatic poly(urethane-amine) (PUA) grafted mesoporous hollow hydroxyapatite (H-HAP) microparticles were prepared via in situ polymerization in supercritical CO2. Thermal-responsive PUA acted as the on–off gates inside the mesoporous H-HAP due to the stretch and shrinkage of the PUA polymer chains at different temperatures. The PUA-grafted hollow HAP (PUA-g-H-HAP) microparticles displayed high specific surface area (95 m2 g−1) and drug loading efficiency (60%). The in vitro drug release studies indicated that PUA-g-H-HAP microparticles exhibited distinguishable pH- and thermal-dependent drug release properties, and PUA on–off switches enabled the DOX release in a reversible way by simply adjusting the environmental temperature. Moreover, compared to the hollow HAP microparticles having a higher amount of released DOX over the initial 2 h (about 24.4% of total released drug over 24 h) at 37 °C and pH 7.4, PUA-g-H-HAP microparticles displayed a sustained release property with the value of only 10.7% deriving from the blockage of the stretched PUA chains inside the mesoporous H-HAP.
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MATERIALS LETTERS
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2014
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IF 2.269
Hongxia Yang,Nan Wang,Yumei Ren,Lu Cai,Zhimin Chen,Qun Xu
Three-dimensional (3D) graphene-pyrrole/carbon nanotubes/polyaniline (GPCP) nanohybrids were successfully prepared through a facile and scalable method with the assistance of supercritical CO 2 (SC CO 2 ), which could be used as efficient electrode materials for supercapacitors . Our experimental results indicate that SC CO 2 can not only help combining multi-component nanocomposites but also improve the conductivity of the nanohybrids. The electrochemical measurements show that the specific capacitance of the as-prepared nanohybrids with the assistance of supercritical CO 2 can run up to 400 F g −1 , which verify that SC CO 2 provides an effective route to the scalable production of 3D nanohybrids for the potential application in supercapacitors.
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高影响因子
Journal of Environmental Sciences
·
2015
·
IF 2.002
Dandan Cheng,Yue Liu,Haiqiang Wang,Xiaole Weng,Zhongbiao Wu
In this study, a series of polyetherimide/SBA-15: 2-D hexagonal P6mm, Santa Barbara USA (PEI/SBA-15) adsorbents modified by phosphoric ester based surfactants (including tri(2-ethylhexyl) phosphate (TEP), bis(2-ethylhexyl) phosphate (BEP) and trimethyl phosphonoacetate (TMPA)) were prepared for CO 2 adsorption. Experimental results indicated that the addition of TEP and BEP had positive effects on CO 2 adsorption capacity over PEI/SBA-15. In particular, the CO 2 adsorption amount could be improved by around 20% for 45PEI–5TEP/SBA-15 compared to the additive-free adsorbent. This could be attributed to the decrease of CO 2 diffusion resistance in the PEI bulk network due to the interactions between TEP and loaded PEI molecules, which was further confirmed by adsorption kinetics results. In addition, it was also found that the cyclic performance of the TEP-modified adsorbent was better than the surfactant-free one. This could be due to two main reasons, based on the results of in situ DRIFT and TG-DSC tests. First and more importantly, adsorbed CO 2 species could be desorbed more rapidly over TEP-modified adsorbent during the thermal desorption process. Furthermore, the enhanced thermal stability after TEP addition ensured lower degradation of amine groups during adsorption/desorption cycles.
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PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2015
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IF 2.587
Song Zhao,Xiaochang Cao,Zijian Ma,Zhi Wang,Zhihua Qiao,Jixiao Wang,Shichang Wang
In this work, imidazolate framework ZIF-8 nanoparticles were synthesized and incorporated into a poly(vinylamine) (PVAm) coating solution. The chemical structure of a PVAm/ZIF-8 film was characterized by X-ray diffraction and attenuated total reflectance Fourier transform infrared spectroscopy techniques. Mixed-matrix membranes (MMMs) were developed by coating the PVAm/ZIF-8 mixed dispersion on a polysulfone (PSf) support membrane. Surface and cross-sectional scanning electron microscopy images of the MMMs were employed to observe the dispersion of nanoparticles in the polymer matrix. The CO2 permeance and CO2/N2 selectivity of the MMMs were evaluated by using a CO2/N2 mixture gas. Optimal preparation parameters for the MMMs were achieved by varying the incorporated ZIF-8 contents in the coating solution and the wet coating thickness. The effect of incorporated ZIF-8 on improving the gas permselectivity was revealed, and the mechanism of CO2-facilitated transport in the PVAm/ZIF-8/PSf membrane was analyzed. The CO2/N2 separation performance of PVAm/ZIF-8/PSf membranes with different wet coating thicknesses was also evaluated at 22–60 °C to analyze the changes of the gas permselectivity with increasing temperature.
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RSC Advances
·
2015
·Vol. 5
·期 70
·56478-56485
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IF 3.84
Guozhi Fan,Shanshan Luo,Qiang Wu,Tao Fang,Jianfen Li,Guangsen Song
A magnetic Fe3O4@SiO2–ZnBr2 catalyst was prepared by supporting ZnBr2 on silica-coated magnetic nanoparticles of Fe3O4 and used as a recoverable catalyst for the direct synthesis of diphenyl carbonate (DPC) from CO2 and phenol in the presence of carbon tetrachloride. The as-prepared catalyst was characterized by infrared spectroscopy (IR), powder X-ray diffraction (XRD), a X-ray photoelectron spectrometer (XPS) and BET. Zn loading in the supported catalyst and leaching during the reaction process were determined by atomic absorption spectroscopy (AAS). It was found that Fe3O4@SiO2–ZnBr2 showed higher catalytic activity than homogenous ZnCl2 and ZnI2 as well as homogenous ZnBr2. With this new catalyst under optimized conditions, a yield of DPC at 28.1% was obtained. The heterogeneous catalyst Fe3O4@SiO2–ZnBr2 can also be recovered by a permanent magnet after the reaction and reused up to 4 times without noticeable deactivation.
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INORGANIC CHEMISTRY
·
2015
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IF 4.762
De-Yun Ma,Zhi Li,Jun-Xia Xiao,Rong Deng,Pei-Feng Lin,Rui-Qun Chen,Yun-Qiu Liang,Hai-Fu Guo,Bei Liu,Jian-Qiang Liu
By using a strategy of introducing hydrophobic groups to the linkers, a hydrostable MOF was constructed based on 5-nitroisophthalate and 2,2′-dimethyl-4,4′-bipyridine coligands, revealing a 3D dia topology structure with a 1D channel parallel to the c axis. TGA, PXRD, and water vapor sorption results show high thermal and water stability for the framework. The framework is very porous and possesses not only high busulfan payloads with an encapsulation efficiency up to 21.5% (17.2 wt %) but also very high CO2 selective capture compared with that of other small gases (i.e., CH4, N2, O2, CO, and H2) at 298 K based on molecular simulations due to the pore surface being populated by methyl and nitryl groups. Furthermore, in vitro MTT assays were conducted on four different cells lines with increasing concentrations of the framework, and the results showed that the framework was nontoxic (cell viability >80%) in spite of the concentrations up to 500 μg/mL.
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PubMed
高影响因子
APPLIED SURFACE SCIENCE
·
2015
·
IF 2.711
Zhiqiao He,Juntao Tang,Jie Shen,Jianmeng Chen,Shuang Song
TiO 2 nanosheets modified with various concentrations of sulfuric acid have been synthesized through hydrothermal treatment at 240 °C followed by heat treatment at 105 °C. Compared with untreated TiO 2 nanosheets, the H 2 SO 4 -modified samples exhibited markedly improved quantum yield (QY), energy returned on energy invested (EROEI), and turnover number (TON) for CO 2 reduction to CH 4 under visible-light irradiation. As supported by physical-chemical characterization, the enhanced photocatalytic activities can be attributed to acidification promoting the formation of hydroxyl groups (Brønsted acidic sites) and oxygen vacancies/Ti 3+ species. Thus, efficient charge separation and transfer to the TiO 2 surface for both CO 2 reduction and the accompanying H 2 O oxidation is facilitated. The highest activity for CO 2 photoreduction to CH 4 was obtained with TiO 2 nanosheets with 0.5 mol L −1 H 2 SO 4 , with QY, EROEI, and TON of 0.726‰, 0.335‰, and 83.124, respectively. Furthermore, the catalyst maintained stable performance throughout five successive recyclability test runs.
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RSC Advances
·
2015
·Vol. 6
·期 4
·2810-2818
·
IF 3.84
Ting Zhang,Xuefeng Wang,Xueli Huang,Yinnian Liao,Jinzhu Chen
Chemical fixation of carbon dioxide (CO2) to cyclic carbonates was investigated by using bifunctional nucleophile–electrophile catalysts of a metallophthalocyanine–carbon nitride hybrid [MPc/g-C3N4 (M = Co, Cu)] in the absence of any co-catalysts and organic solvents. MPc/g-C3N4 was readily obtained by direct calcination of a mixture of dicyandiamide and metallophthalocyanine under a flowing-nitrogen atmosphere, and the MPc/g-C3N4 prepared at 480 °C (MPc/g-C3N4-480) showed the highest catalytic performance toward the cycloaddition reaction of CO2 to epichlorohydrin (ECH). For bifunctional MPc/g-C3N4, the MPc species function as Lewis acidic centers for ECH activation via electrophilic attack; while, the g-C3N4 moiety, possessing abundant and uncondensed species with the forms of primary amine (NH2) groups and secondary amine (C–NH–C) groups at the edges of graphitic sheets as edge defects, acts as an organic base for CO2 activation through nucleophilic attack. The developed MPc/g-C3N4 is stable and insoluble in any commonly used organic solvents and behaves as heterogeneous catalyst, leading to facile separation and recycling in a CO2 fixation reaction.
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JOURNAL OF SUPERCRITICAL FLUIDS
·
2014
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IF 2.571
Qin-Qin Xu,Yu-Ling Ma,Gang-Xu,Jian-Zhong Yin,Ai-Qin Wang,Jin-Ji Gao
Well-defined Ag nanowires were obtained in SBA-15 at a short deposition time of 5 min in supercritical CO 2 when adding a small amount of ethylene glycol as the co-solvent. Ethylene glycol played a key role in dictating the nanowire morphology. Through detailed investigation of the whole deposition process, including the dissolution of precursor assisted by the co-solvent, the diffusion properties of the precursor into the nano-scale channels of the substrate, and the interaction between the precursor and the substrate, we found that a small amount of precursors were reduced into Ag 0 by ethylene glycol at the initial stage of the deposition. The resultant Ag 0 then acted as nuclei leading to a non-equilibrium sorption of the precursor. The rapid adsorption of the precursor onto the substrate resulted in a high loading of Ag in a short deposition time and the formation of nanowire morphology. Furthermore, this method was successfully extended to other porous substrates such as γ-Al 2 O 3 , SiO 2 and KIT-6, demonstrating its great potentials in the synthesis of nanocomposites.
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Journal of Materials Chemistry A
·
2017
·Vol. 5
·期 6
·2619-2628
·
IF 8.867
Yuzhen Zhu,Zaixiang Xu,Wenya Jiang,Shuxian Zhong,Leihong Zhao,Song Bai
The utilization of a metal cocatalyst is a promising route to improve the solar-to-chemical conversion efficiency of semiconductor-based photocatalysts. The efficiency of the improvement is greatly dependent on the architectural structure of the metal cocatalysts, especially the catalytically active sites on the surface of the cocatalysts. In this article, Pd nanosheets with different sizes have been hybridized with TiO2 nanosheets to disclose how the edge of Pd cocatalysts influences the photocatalytic performance of TiO2–Pd hybrid structures in the reduction of CO2 to fuels. It was found that the highest photocatalytic activity was realized by small Pd nanosheets with the highest edge density on the TiO2 nanosheets. The reason is that the edges of the nanosheets act as the highly active sites for the CO2 reduction reaction. To further verify the edge-dependent photocatalytic performance, Pd nanorings were also deposited on the TiO2 nanosheets, which further improve the photocatalytic activity as compared with original nanosheets resulting from the additional edge sites exposed on the side of the hollow interior in the rings. This work underlines the importance in the edge engineering on the surface of cocatalysts in realizing high-performance photocatalytic applications.
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