过刊目录

2014, Vol. 23, No. 6　Online: 2014-11-24


上一期    下一期

Ran and coworkers in their Article on pages 684–693 reported a facile method to prepare porous membrane by combining liquidliquid phase separation with pyrolysis process and using polyacrylonitrile as carbon source and polyvinylpyrrolidone as poreforming agent. The resulting porous materials have well-defined hierarchical porosity and thus possess great electrochemical capacitive performance for using as supercapacitor.

全全选选:

导出引用 EndNote Ris BibTeX

隐藏/显示图片

COMMUNICATIONS

Select

Partially crystallized Pd nanoparticles decorated TiO2 prepared by atmospheric-pressure cold plasma andits enhanced photocatalytic performance Zhijian Xu, Bin Qi, Lanbo Di, Xiuling Zhang 2014, 23(6): 679-683.  DOI: 10.1016/S2095-4956(14)60199-6 摘要 ( 5747 )   TiO2 decorated with partially crystallized Pd nanoparticles (Pd/TiO2-P) was successfully prepared by atmospheric-pressure dielectric barrier discharge cold plasma. The XRD and XPS analyses proved that Pd ions were reduced to partially crystallized metallic Pd nanoparticles in Pd/TiO2-P. The XPS spectra also indicated that an enhanced metal-support interaction was formed due to the existence of partially crystallized Pd nanoparticles with lower coordination number in Pd/TiO2-P. Photocatalytic activity of Pd/TiO2-P was much higher than that of TiO2 samples decorated with well crystallized Pd nanoparticles.

ARTICLES

Select

A hierarchical porous carbon membrane from polyacrylonitrile/polyvinylpyrrolidone blending membranes: Preparation, characterization and electrochemical capacitive performance Huili Fan, Fen Ran, Xuanxuan Zhang, Haiming Song, Wenxia Jing, Kuiwen Shen, Lingbin Kong, Long Kang 2014, 23(6): 684-693.  DOI: 10.1016/S2095-4956(14)60200-X 摘要 ( 6781 )   Novel hierarchical porous carbon membranes were fabricated through a simple carbonization procedure of well-defined blending polymer membrane precursors containing the source of carbon polyacrylonitrile (PAN) and an additive of polyvinylpyrrolidone (PVP), which was prepared using phase inversion method. The as-fabricated materials were further used as the active electrode materials for supercapacitors. The effects of PVP concentration in the casting solution on structure feature and electrochemical capacitive performance of the as-prepared carbon membranes were also studied in detail. As the electrode material for supercapacitor, a high specific capacitance of 278.0 F/g could be attained at a current of 5 mA/cm2 and about 92.90% capacity retention could be maintained after 2000 charge/discharge cycles in 2 mol/L KOH solution with a PVP concentration of 0.3 wt% in the casting solution. The facile hierarchical pore structure preparation method and the good electrochemical capacitive performance make the prepared carbon membrane particularly promising for use in supercapacitor.

Select

Gas-phase electrocatalytic reduction of carbon dioxide using electrolytic cell based on phosphoric acid-doped polybenzimidazole membrane Dunfeng Gao, Fan Cai, Qinqin Xu, Guoxiong Wang, Xiulian Pan, Xinhe Bao 2014, 23(6): 694-700.  DOI: 10.1016/S2095-4956(14)60201-1 摘要 ( 6979 )   Carbon dioxide transformation to fuels or chemicals provides an attractive approach for its utilization as feedstock and its emission reduction. Herein, we report a gas-phase electrocatalytic reduction of CO2 in an electrolytic cell, constructed using phosphoric acid-doped polybenzimidazole (PBI) membrane, which allowed operation at 170℃. Pt/C and PtMo/C with variable ratio of Pt/Mo were studied as the cathode catalysts. The results showed that PtMo/C catalysts significantly enhanced CO formation and inhibited CH4 formation compared with Pt/C catalyst. Characterization by X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy revealed that most Mo species existed as MoO3 in PtMo/C catalysts and the interaction between Pt and MoOx was likely responsible for the enhanced CO formation rate although these bicomponent catalysts in general had a larger particle size than Pt/C catalyst.

Select

Oxygen-deficient titania as alternative support for Pt catalysts for the oxygen reduction reaction Anqi Zhao, Justus Masa, Wei Xia 2014, 23(6): 701-707.  DOI: 10.1016/S2095-4956(14)60202-3 摘要 ( 6973 )   Insufficient electrochemical stability is a major challenge for carbon materials in oxygen reduction reaction (ORR) due to carbon corrosion and insufficient metal-support interactions. In this work, titania is explored as an alternative support for Pt catalysts. Oxygen deficient titania samples including TiO2-x and TiO2-xNy were obtained by thermal treatment of anatase TiO2 under flowing H2 and NH3, respectively. Pt nanoparticles were deposited on the titania by a modified ethylene glycol method. The samples were characterized by N2-physisorption, X-ray diffraction and X-ray photoelectron spectroscopy. The ORR activity and long-term stability of supported Pt catalysts were evaluated using linear sweep voltammetry and chronoamperometry in 0.1 mol/L HClO4. Pt/TiO2-x and Pt/TiO2-xNy showed higher ORR activities than Pt/TiO2 as indicated by higher onset potentials. Oxygen deficiency in TiO2-x and TiO2-xNy contributed to the high ORR activity due to enhanced charge transfer, as disclosed by electrochemical impedance spectroscopy studies. Electrochemical stability studies revealed that Pt/TiO2-x exhibited a higher stability with a lower current decay rate than commercial Pt/C, which can be attributed to the stable oxide support and strong interaction between Pt nanoparticles and the oxygen-deficient TiO2-x support.

Select

Isobutane dehydrogenation over chromia alumina catalysts prepared from MIL-101: Insight into chromium species on activity and selectivity Huahua Zhao, Huanling Song, Zhichao Miao, Lingjun Chou 2014, 23(6): 708-716.  DOI: 10.1016/S2095-4956(14)60203-5 摘要 ( 6500 )   Various mesoporous chromia alumina catalysts were prepared by five different methods based on a metal-organic framework MIL-101 and their catalytic performances over isobutane dehydrogenation were investigated. The highly dispersed chromium species were produced on catalyst KCrAl-I1 with largest specific surface area of 198 m2·g-1 prepared with aluminium isopropoxide (Al(i-OC3H7)3) by ultrasonic impregnation method. However, the catalyst KCrAl-I2 synthesized by stirring impregnation possessed crystalline α-Cr2O3 phase, which was poorly dispersed. Two types of Cr-rich and Al-rich CrxAl2-xO3 solid solutions, designated as CrAl-I and CrAl-II phase, were formed over the catalysts KCrAl-I3 (prepared by Al(i-OC3H7)3 with nitric acid regulation), KCrAl-C4 (prepared by aluminium chloride hexahydrate) and KCrAl-N5 (prepared by aluminium nitrate nonahydrate). Catalytic evaluation results revealed that KCrAl-I1 exhibited the high isobutane conversion due to its highly dispersed chromium species. However, KCrAl-I3, KCrAl-C4 and KCrAl-N5 showed the higher isobutene selectivity (95.2%-96.4%) on account of the formation of chromia alumina solid solutions in the catalysts. Moreover, the solid solution over the chromia alumina catalysts could greatly suppress the coke formation.

Select

Preparation of composite poly(ether block amide) membrane for CO2 capture Lianjun Wang, Yang Li, Shuguang Li, Pengfei Ji, Chengzhang Jiang 2014, 23(6): 717-725.  DOI: 10.1016/S2095-4956(14)60204-7 摘要 ( 6539 )   In this study, a poly(ether block amide) (Pebax 1657) composite membrane applied for CO2 capture was prepared by coating Pebax 1657 solution on polyacrylonitrile (PAN) ultrafiltration membrane. Ethanol/water mixture was used as the solvent of Pebax and the effects of ethanol/water mass ratios and Pebax concentration on the permeation properties of composite membrane were studied. To enhance the composite membrane permeance, the gutter layer, made from reactive amino silicone crosslinking with polydimethylsiloxane (PDMS), was designed. The influence of crosslinking degree of the gutter layer on membrane performance was investigated. As a result, a Pebax/amino-PDMS/PAN multilayer membrane with hexane resistance was developed, showing CO2 permeance of 350 GPU and CO2/N2 selectivity over 50. The blend of polyethylene glycol dimethyl ether (PEG-DME) with Pebax as coating material was studied to further improve the membrane performance. After being combined with PEG-DME additive, CO2 permeance of the final Pebax-PEG-DME/amino-PDMS/PAN composite membrane reached 400 GPU above with CO2/N2 selectivity over 65.

Select

Synergetic effects of NaAlH4-TiF3 co-additive on dehydriding reaction of Mg(AlH4)2 Ying Wang, Li Li, Fangyuan Qiu, Cuihua An, Yijing Wang, Lifang Jiao, Huatang Yuan 2014, 23(6): 726-731.  DOI: 10.1016/S2095-4956(14)60205-9 摘要 ( 5615 )   The effects of NaAlH4, TiF3 and NaAlH4-TiF3 co-additive on dehydriding reaction of Mg(AlH4)2 are systematically investigated. The onset dehydrogenation temperature of the co-doped Mg(AlH4)2 composites decreased to 74℃, which is about 59℃ lower than that of pure Mg(AlH4)2. The dehydrogenation kinetics of NaAlH4-TiF3 co-doped Mg(AlH4)2 sample was also improved, which released about 94% hydrogen within 48 min, but no visible hydrogen was released from pure Mg(AlH4)2 under the same conditions. The activation energy of co-doped Mg(AlH4)2 was 85.6 kJ·mol-1, which was significantly lower than that of additive-free Mg(AlH4)2 sample. The synergetic effects of NaAlH4 and TiF3 on the dehydrogenation performance of Mg(AlH4)2 were confirmed. In addition, a possible catalytic mechanism is discussed, regarding the different roles of NaAlH4 and TiF3 on Mg(AlH4)2.

Select

Fractional pyrolysis of Cyanobacteria from water blooms over HZSM-5 for high quality bio-oil production Huijuan Li, Linling Li, Rui Zhang, Dongmei Tong, Changwei Hu 2014, 23(6): 732-741.  DOI: 10.1016/S2095-4956(14)60206-0 摘要 ( 6412 )   Fractional pyrolysis and one-step pyrolysis of natural algae Cyanobacteria from Taihu Lake were comparatively studied from 200 to 500℃. One-step pyrolysis produced bio-oil with complex composition and low high heating value (HHV≤qslant30.9 MJ/kg). Fractional pyrolysis separated the degradation of different components in Cyanobacteria and improved the selectivity to products in bio-oil. That is, acids at 200℃, amides and acids at 300℃, phenols and nitriles at 400℃, and phenols at 500℃, were got as main products, respectively. HZSM-5 could promote the dehydration, cracking and aromatization of pyrolytic intermediates in fractional pyrolysis. At optimal HZSM-5 catalyst dosage of 1.0 g, the selectivity to products and the quality of bio-oil were improved obviously. The main products in bio-oil changed to nitriles (47.2%) at 300℃, indoles (51.3%) and phenols (36.3%) at 400℃. The oxygen content was reduced to 7.2 wt% and 9.4 wt%, and the HHV was raised to 38.1 and 37.3 MJ/kg at 300 and 400℃, respectively. Fractional catalytic pyrolysis was proposed to be an efficient method not only to provide a potential solution for alleviating environmental pressure from water blooms, but also to improve the selectivity to products and obtain high quality bio-oil.

Select

Efficient oxidation of ethylbenzene catalyzed by cobalt zeolitic imidazolate framework ZIF-67 and NHPI Hongyan Li, Hong Ma, Xinhong Wang, Jin Gao, Chen Chen, Song Shi, Minjie Qu, Na Feng, Jie Xu 2014, 23(6): 742-746.  DOI: 10.1016/S2095-4956(14)60207-2 摘要 ( 7150 )   Efficient catalytic oxidation of ethylbenzene to acetophenone was realized using the catalytic system of cobalt zeolitic imidazolate framework ZIF-67/N-hydroxyphthalimide (NHPI) under mild conditions. 95.2% conversion of ethylbenzene with 90.3% selectivity to acetophenone could be obtained at 373 K under 0.3 MPa O2 for 9 h. The results show that there exists synergetic effect between ZIF-67 and NHPI. 1-Phenylethyl hydroperoxide (PEHP) was generated via a radical process involving the hydrogen abstraction from ethylbenzene by phthalimide N-oxyl, and subsequently effectively decomposed to acetophenone by ZIF-67.

Select

Molecular dynamics simulations for the growth of CH4-CO2 mixed hydrate Lizhi Yi, Deqing Liang, Xuebing Zhou, Dongliang Li 2014, 23(6): 747-754.  DOI: 10.1016/S2095-4956(14)60208-4 摘要 ( 7199 )   Molecular dynamics simulations are performed to study the growth mechanism of CH4-CO2 mixed hydrate in xCO2=75%, xCO2=50%, and xCO2=25% systems at T=250 K, 255 K and 260 K, respectively. Our simulation results show that the growth rate of CH4-CO2 mixed hydrate increases as the CO2 concentration in the initial solution phase increases and the temperature decreases. Via hydrate formation, the composition of CO2 in hydrate phase is higher than that in initial solution phase and the encaging capacity of CO2 in hydrates increases with the decrease in temperature. By analysis of the cage occupancy ratio of CH4 molecules and CO2 molecules in large cages to small cages, we find that CO2 molecules are preferably encaged into the large cages of the hydrate crystal as compared with CH4 molecules. Interestingly, CH4 molecules and CO2 molecules frequently replace with each other in some particular cage sites adjacent to hydrate/solution interface during the crystal growth process. These two species of guest molecules eventually act to stabilize the newly formed hydrates, with CO2 molecules occupying large cages and CH4 molecules occupying small cages in hydrate.

Select

Co-modified Pd/CeO2-ZrO2 catalysts for methanol decomposition Ming Zhao, Hailong Zhang, Xue Li, Yaoqiang Chen 2014, 23(6): 755-760.  DOI: 10.1016/S2095-4956(14)60209-6 摘要 ( 5534 )   Pd/Ce0.8Zr0.2O2 catalysts modified by cobalt were prepared by a sequential impregnation method and characterized by X-ray powder diffraction (XRD), N2 adsorption/desorption (Brunauer-Emmet-Teller), oxygen storage capacity (OSC), CO-chemisorption, H2-temperature-programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The effect of Co on the performance of methanol decomposition was evaluated at a fixed-bed microreactor. The results showed that the addition of Co can improve the oxygen storage capacity of the catalyst and the dispersion of Pd. XPS results indicated that Pd was in a partly oxidized (Pdδ+, 1<δ<2) state and Co2+ was present in Pd catalysts modified by Co. A 90% conversion of methanol was achieved at around 280℃ over Pd-Co/Ce0.8Zr0.2O2 catalyst which was 20℃ lower than that over Pd/Ce0.8Zr0.2O2, indicating that both Pdδ+and Co2+ play an important role in improving the catalytic activity of methanol decomposition.

Select

Coking-resistant Ni-ZrO2/Al2O3 catalyst for CO methanation Qing Liu, Fangna Gu, Jiajian Gao, Huifang Li, Guangwen Xu, Fabing Su 2014, 23(6): 761-770.  DOI: 10.1016/S2095-4956(14)60210-2 摘要 ( 5493 )   Highly coke-resisting ZrO2-decorated Ni/Al2O3 catalysts for CO methanation were prepared by a two-step process. The support was first loaded with NiO by impregnating method and then modified with ZrO2 by deposition-precipitation method (IM-DP). Nitrogen adsorption-desorption, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, H2 temperature-programmed reduction and desorption, NH3 temperature-programmed desorption, and zeta potential analysis were employed to characterize the samples. The results revealed that, compared with the catalysts with the same composition prepared by co-impregnation (CI) and sequential impregnation (SI) methods, the Ni/Al2O3 catalyst prepared by IM-DP showed much enhanced catalytic performance for syngas methanation under the condition of atmospheric pressure and a high weight hourly space velocity of 120000 mL·g-1·h-1. In a 80 h life time test under the condition of 300--600℃ and 3.0 MPa, this catalyst showed high stability and resistance to coking, and the amount of deposited carbon was only 0.4 wt%. On the contrary, the deposited carbon over the catalyst without ZrO2 reached 1.5 wt% after a 60 h life time test. The improved catalytic performance was attributed to the selective deposition of ZrO2 nanoparticles on the surface of NiO rather than Al2O3, which could be well controlled via changing the electrostatic interaction in the DP procedure. This unique structure could enhance the dissociation of CO2 and generate surface oxygen intermediates, thus preventing carbon deposition on the Ni particles in syngas methanation.

Select

Effect of external surface of HZSM-5 zeolite on product distribution in the conversion of methanol to hydrocarbons Junhui Li, Yanan Wang, Wenzhi Jia, Zhiwen Xi, Huanhui Chen, Zhirong Zhu, Zhonghua Hu 2014, 23(6): 771-780.  DOI: 10.1016/S2095-4956(14)60211-4 摘要 ( 6128 )   The external surface of HZSM-5 zeolite was passivated by liquid siliceous deposition and by acidic sites poisoning with lepidine, respectively. Then methanol-to-hydrocarbons (MTH) reaction was investigated over the above as-prepared catalysts and the dissoluble coke on these used catalysts was analyzed by GC-MS, to study the role of the external surface of HZSM-5 in the catalytic reaction. Comparison with the experimental results based on parent ZSM-5 showed that the product distribution of MTH reaction was obviously influenced by the external surface. Evidences were listed as follows: (1) the final product on parent HZSM-5 showed higher aromatic selectivity, lower olefin selectivity, lower ratio of C2/C3+ aliphatics and higher ratio of C3/C4+ aliphatics than the reaction mixture produced by the sole catalysis of acidic sites in HZSM-5 channel; (2) a little of pentamethylbenzene and hexamethylbenzene in the product on parent HZSM-5, was produced via multi-methylation of methylbenzene on the external surface. The above conclusion may also be suitable for MTH reaction over other zeolites with 10-ring channel.

Select

Doping effects of manganese on the catalytic performance and structure of NiMgO catalysts for controllabe synthesis of multi-walled carbon nanotubes Maofei Ran, Wei Chu, Yan Liu, Dong Liu, Chang Zhang, Jiae Zheng 2014, 23(6): 781-788.  DOI: 10.1016/S2095-4956(14)60212-6 摘要 ( 6259 )   Doping effects of manganese (Mn) on catalytic performance and structure evolution of NiMgO catalysts for synthesis of multi-walled carbon nanotubes (MWCNTs) from methane were investigated for the first time. Addition of Mn in NiMgO catalyst can greatly improve the MWCNTs yield. Mn0.2NiMgO catalyst among the tested ones gives the highest MWCNTs yield as 2244%, which is two times higher than that of the catalyst without Mn. The structure evolution, reduction behaviors and surface chemical properties of MnNiMgO catalysts with various Mn contents were studied in detail. It was found that the stable solid solution of NiMgO2 formed in NiMgO catalyst was disturbed by the addition of Mn. Instead, another solid solution of MnMg6O8 is formed. More amount of Ni can be reduced and dispersed on the catalyst surface to be acted as active sites. Importantly, the changes of Ni content on the surface are correlated with the Ni particle size and the outer diameter of MWCNTs, suggesting the controllable synthesis of MWCNTs over MnNiMgO catalysts.

Select

Study on structural characteristics and adsorption performance of ultrasonic treated Mn-containing sulfur transfer agent Ruiyu Jiang, Jiling Zhang, Lei Zhang, Qinfang Zhang, Guihua Hou, Ning Xu 2014, 23(6): 789-794.  DOI: 10.1016/S2095-4956(14)60213-8 摘要 ( 5890 )   To prepare manganese-containing spinel sulfur transfer agent with acid peptization, ultrasonic wave is used for the first time to modify the structure of sulfur transfer agent in this work. Mini fixed bed reactor was used to investigate the effect of ultrasonic power, time and temperature on the structure and oxidation adsorption performance of sulfur transfer agent and the adsorption kinetics and mechanism of SO2 were analyzed. SEM, TEM, XRD and N2 adsorption-desorption techniques were employed to characterize and analyse the function of sulfur transfer agent. The results indicated that manganese-containing spinel is a kind of promising sulfur transfer agent and exhibits higher sulfur capacity and desulfurization degree under the selected conditions of the ultrasonic wave power of 60%, and with the treatment period for 3 h at a temperature of 60℃.

Select

Performance of Co/MgO catalyst for CO2 reforming of toluene as a model compound of tar derived from biomass gasification Xiuxiu Bao, Meng Kong, Wen Lu, Jinhua Fei, Xiaoming Zheng 2014, 23(6): 795-800.  DOI: 10.1016/S2095-4956(14)60214-X 摘要 ( 5517 )   Catalytic performances of the CO2 reforming of toluene on Co/MgO catalysts with different cobalt loadings were evaluated in a fluidized-bed reactor. The results showed that the conversion of toluene and the stability of Co/MgO increased, but the apparent reaction rate decreased at the initial stage with increasing the amount of metallic Co formed from the reduction of Co/MgO catalysts at 700℃. The deactivation of Co/MgO catalysts was mainly resulted from that a part of the metallic Co was oxidized by CO2 and could not be re-reduced by H2 at reaction temperature. Therefore, the excess metallic Co on the higher Co loading catalysts was beneficial to the catalyst stability.

Select

Investigation of Co3O4 nanorods supported Pd anode catalyst for methanol oxidation in alkaline solution Yanbiao Ren, Shichao Zhang, Hua Fang, Xin Wei, Puheng Yang 2014, 23(6): 801-808.  DOI: 10.1016/S2095-4956(14)60215-1 摘要 ( 5789 )   A Co3O4 nanorod supported Pd electro-catalyst for the methanol electro-oxidation (MEO) has been fabricated by the combination of hydrothermal synthesis and microwave-assisted polyol reduction processes. The crystallographic property and microstructure have been characterized using XRD, SEM and TEM. The results demonstrate that Pd nanoparticles (PdNPs) with a narrow particle size distribution (3-5 nm) are uniformly deposited onto the surface of Co3O4 nanorods. Electrochemical measurements show that this catalyst having a larger electrochemically active surface area and a more negative onset-potential exhibits enhanced catalytic activity of 504 mA/mg Pd for MEO comparing with the Pd/C catalyst (448 mA/mg Pd). The dependency of logI against logv reveals that MEO on Pd-Co3O4 electrode is under a diffusion control. Electrochemical impedance spectroscopy (EIS) measurement agrees well with the CV results. The minimum charge transfer resistance of MEO on Pd-Co3O4 is observed at -0.05 V, which coincides with the potential of MEO peak.

Select

Magnetization-induced double-layer capacitance enhancement in active carbon/Fe3O4 nanocomposites Guoxiang Wang, Hongfeng Xu, Lu Lu, Hong Zhao 2014, 23(6): 809-815.  DOI: 10.1016/S2095-4956(14)60216-3 摘要 ( 6321 )   The effects of magnetic fields on electrochemical processes have made a great impact on both theoretical and practical significances in improving capacitor performance. In this study, active carbon/Fe3O4-NPs nanocomposites (AC/Fe3O4-NPs) were synthesized using a facile hydrothermal method and ultrasonic technique. Transmission electron micrographs (TEM) showed that Fe3O4 nanoparticles (Fe3O4-NPs) grew along the edge of AC. AC/Fe3O4-NPs nanocomposites were further used as an electrochemical electrode, and its electrochemical performance was tested under magnetization and non-magnetization conditions, respectively, in a three-electrode electrochemical device. Micro-magnetic field could improve the electric double-layer capacitance, reduce the charge transfer resistance, and enhance the discharge performance. The capacitance enhancement of magnetized electrode was increased by 33.1% at the current density of 1 A/g, and the energy density was improved to 15.97 Wh/kg, due to the addition of magnetic particles.