CHINESE JOURNAL OF ANALYTICAL CHEMISTRY
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2015
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IF 0.754
Yang LI,Jin-Ke ZHU,Hua FENG,Lian-Jie LI,Deng-Gao JIANG
Cellulose acetylsalicylate chiral stationary phase (ACSP) was synthesized by using cellulose and o -acetylsalicylryl chloride, and its enantioseparation ability was evaluated by high performance liquid chromatography (HPLC). Commercial Chiralcel OJ column was evaluated for comparison. The effects of mobile phase composition and double ester carbonyls of derivative on enantioseparation were investigated. The structure of the obtained derivative was characterized by infrared (IR) spectroscopy and thermogravimetric analysis. Hexane-isopropanol (90:10–80:20, V/V , 0.1% DEA or TFA) was selected by comparison of four mobile phases, namely hexane-isopropanol, hexane-ethanol, hexane-methanol-isopropanol and hexane-methanol-dichloroethane. Seven racemates of catecholamines and amides were used to evaluate its chiral recognition ability in normal phase elution mode, and the regularity and characteristics of the novel chiral stationary phase were explored. The chromatographic results showed that cellulose ACSP exhibited high enantioseparation ability for catecholamines and some racemates with amide group due to the hydrogen-bond, dipole interaction of carbonyls of acetylsalicylate and the π-π interaction with benzene ring, and the optimum amount of diethylamine or trifluoroacetic acid was 0.1%.
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高影响因子
CHINESE JOURNAL OF CATALYSIS
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2015
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IF 1.964
Min Zhang,Yong Yang,Liban Chen
Double metal cyanide (DMC) catalysts are generally prepared by coprecipitation of potassium hexacyanocobaltate(III) with zinc chloride followed by complexation with tert -butanol, and these materials have been used for several decades in the copolymerization of CO 2 and epoxides. However, the catalytic efficiency of DMC catalysts can be adversely affected by the presence of excess K + , and the preparation of these catalysts can therefore become complicated and time-consuming because of the multiple washing and centrifugation stages required for the removal of the excess K + . In this study, 18-crown-6 ether was used as an effective co-complexing agent for the removal of K + . A series of DMCs containing 18-crown-6 were prepared with different quantities of the crown ether and different washing times. The resulting crown ether-complexing catalysts (CDMCs) and DMC catalysts without crown ether were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis-IR and X-ray diffraction. These characterization results showed that the inclusion of 18-crown-6 allowed for the formation of uniform and highly dispersed CDMC catalysts. In contrast, the DMC catalysts prepared in the absence of 18-crown-6 became uneven and delaminated during the purification by centrifugation, with high- and low-density portions of the material forming on the bottom and top of the catalyst cakes, respectively. The inclusion of 18-crown-6 not only trapped K + but also participated in the complexion process. The complexion of tert -BuOH and 18-crown-6 led to a less crystalline form of the CDMC catalyst. Elemental analysis revealed that CDMC1 contained 1.2% K + . The copolymer was obtained by the copolymerization of CO 2 with propylene oxide using CDMC3 catalyst, which was superior to the copolymer prepared using DMC1. CDMC3 was as active as DMC2 prepared without the crown ether but with seven washing steps. A hypothetical two-stage catalytic mechanism was proposed.
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高影响因子
CHINESE JOURNAL OF CATALYSIS
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2015
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IF 1.964
Bing Cai,Wen-Hua Zhang,Jieshan Qiu
Control of the morphology and coverage of high-quality perovskite films is the main issue affecting planar-structured perovskite solar cells fabricated by solution processing. In this work, the solvent engineering of mixed solutions for spin-coating uniform perovskite thin films was investigated in detail by adding different ratios of N,N -dimethylformamide (DMF) or γ-butyrolactone (GBL) to dimethyl sulfoxide (DMSO). The morphology and film thickness of the resulting perovskite films were found to be significantly altered. At 20%~40% (volume fraction) of N , N -dimethylformamide mixed with DMSO, micrometer scale grains and reduced grain boundaries were observed on the highly uniform perovskite thin films. The optimized planar-structured perovskite solar cells showed power conversion efficiency as high as 16.5% and a stabilized efficiency of 14.4% at a fixed forward bias of 0.88 V.
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高影响因子
CHINESE JOURNAL OF CATALYSIS
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2015
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IF 1.964
Huanan Cui,Jianying Shi,Hong Liu
NaBiO 3 and Bi(NO 3 ) 3 were used to synthesize Bi-doped NaTaO 3 . The influence of the Bi chemical state on the photocatalytic activity was investigated using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and diffused reflectance spectroscopy to study the structure, chemical state and light absorption characteristics, respectively. The photocatalytic activity was evaluated by the H 2 evolution water splitting reaction. The monoclinic phase of NaTaO 3 remained intact for the two Bi-doped samples, but the Ta–O–Ta bond was distorted from 180° after Bi doping. XPS results indicated that Bi 3+ was doped into NaTaO 3 with the Bi(NO 3 ) 3 precursor, while Bi 5+ and Bi 3+ were doped into NaTaO 3 with the NaBiO 3 precursor. The two samples showed identical light absorption, where doping with Bi extended the light absorption to long wavelength light as expected. However, Bi 3+ doping did not promote the photocatalytic activity of NaTaO 3 , while Bi 5+ and Bi 3+ doping did. The distorted Ta–O–Ta bond from 180° due to doping with Bi was detrimental for charge carrier transfer in the photocatalytic process. In contrast, the vacancies or defects in the NaTaO 3 lattice induced by Bi doping for charge balance were beneficial for charge carrier separation. The opposing action of these two factors resulted in the activity of the Bi 3+ -doped sample being comparable with pristine NaTaO 3 . For Bi 5+ - and Bi 3+ -doped NaTaO 3 , a high concentration of defects was induced by the high valence Bi 5+ ion and this led to its higher photocatalytic activity. Our results indicated that charge carrier transfer is a priority factor in the photocatalytic process and the doping of a high valence ion in the ABO 3 structure is a way to promote the separation of charge carriers.
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高影响因子
CHINESE JOURNAL OF CATALYSIS
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2015
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IF 1.964
Fu Yang,Shuying Gao,Cuirong Xiong,Haiqing Wang,Jin Chen,Yan Kong
The different amounts of [5,10,15,20-tetrakis-(pentafluorophenyl)porphyrin] manganese chloride (TF 20 PPMnCl) were immobilized on amino-functionalized MCM-41 for catalysis of the hydroxylation of naphthalene . The samples were characterized by X-ray powder diffraction, N 2 adsorption/desorption isotherms, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, diffuse reflectance ultraviolet-visible spectroscopy, thermogravimetric and differential scanning calorimetry , and inductively coupled plasma mass spectrometry . The results indicated that the manganese porphyrins were axially coordinated on amino-functionalized MCM-41. The prepared samples showed remarkable catalytic activity in the hydroxylation of naphthalene with meta -chloroperbenzoic acid as the oxidant. The catalyst could be reused several times without loss of its activity.
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高影响因子
Journal of Energy Chemistry
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2015
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IF 2.352
Feifei Sun,Yue An,Lecheng Lei,Fuying Wu,Jingke Zhu,Xingwang Zhang
Hydrogenation of carbazole and N-ethylcarbazole over Raney-Ni catalyst were realized in the temperature range of 393–503 K. 4[H] adduct dominated the hydrogenation products and the formation of 2[H] adduct was the rate-limiting step during the period, in which the conversion of carbazole was less than 40%. The hydrogenation process followed pseudo-first-order kinetics and the hydrogenation activation energies of carbazole and N-ethylcarbazole were 90 kJ/mol and 115 kJ/mol, respectively. The reaction starting position as well as the pathway of the hydrogenation of (N-ethyl)carbazole were investigated by comparing the kinetic characteristics of hydrogen uptake of carbazole and N-ethylcarbazole. The results showed that the reaction was a stepwise hydrogenation process and the first H 2 was added to the C1 = C10 double bond in the hydrogenation.
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高影响因子
SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS
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2014
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IF 2.613
Yoshiaki Oda,Heping Shen,Lin Zhao,Jianbao Li,Mitsumasa Iwamoto,Hong Lin
An environmentally friendly solid-state quantum dot sensitized solar cell (ss-QDSSC) was prepared by combining colloidal SnS QDs as the sensitizer and organic hole scavenger spiro-OMeTAD (2,2′,7,7′-tetrakis-(N,N-di-p-methoxyphenylamine)9,9′-spirobifluorene) as the solid-state electrolyte, and the energy alignment of SnS and TiO2 was investigated. The bandgap of colloidal SnS QDs increased with decreasing particle size from 14 to 4 nm due to an upshift of the conduction band and a downshift of the valence band. In TiO2/SnS heterojunctions, the conduction band minimum (CBM) difference between TiO2 and SnS was as large as ∼0.8 eV; this difference decreased with decreasing particle size, but was sufficient for electron injection from SnS nanoparticles of any size into TiO2. Meanwhile, the sensitizer regeneration driving force, that is, the difference between the valence band maximum (VBM) of SnS and the work function of the electrolyte, showed an opposite behaviour with the SnS size due to a downward shift of the SnS VB. Consequently, smaller SnS QDs should result in a more efficient charge transfer in heterojunctions, revealing the advantages of QDs vs larger particles as sensitizers. This prediction was confirmed by the improved photovoltaic performance of ss-QDSSCs modified with SnS nanoparticles, which peaked for 5–6 nm sized SnS nanoparticles due to the balance between electron injection and sunlight absorption.
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PubMed
高影响因子
CHINESE JOURNAL OF CATALYSIS
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2015
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IF 1.964
Yanyan Xu,Mingming Gao,Guohui Zhang,Xinhua Wang,Jiajia Li,Shuguang Wang,Yuanhua Sang
An electrochemically reduced graphene oxide sample, ERGO -0.8V , was prepared by electrochemical reduction of graphene oxide (GO) at –0.8 V, which shows unique electrocatalytic activity toward tetracycline (TTC) detection compared to the ERGO -1.2V (GO applied to a negative potential of –1.2 V), GO, chemically reduced GO (CRGO)-modified glassy carbon electrode (GC) and bare GC electrodes. The redox peaks of TTC on an ERGO -0.8V -modified glass carbon electrode (GC/ERGO -0.8V ) were within 0–0.5 V in a pH 3.0 buffer solution with the oxidation peak current correlating well with TTC concentration over a wide range from 0.1 to 160 mg/L. Physical characterizations with Fourier transform infrared (FT-IR), Raman, and X-ray photoelectron spectroscopies (XPS) demonstrated that the oxygen-containing functional groups on GO diminished after the electrochemical reduction at –0.8 V, yet still existed in large amounts, and the defect density changed as new sp 2 domains were formed. These changes demonstrated that this adjustment in the number of oxygen-containing groups might be the main factor affecting the electrocatalytic behavior of ERGO. Additionally, the defect density and sp 2 domains also exert a profound influence on this behavior. A possible mechanism for the TTC redox reaction at the GC/ERGO -0.8V electrode is also presented. This work suggests that the electrochemical reduction is an effective method to establish new catalytic activities of GO by setting appropriate parameters.
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高影响因子
CHINESE JOURNAL OF CATALYSIS
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2015
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IF 1.964
Xin Zhao,Lei Huang,Hongrui Li,Hang Hu,Jin Han,Liyi Shi,Dengsong Zhang
Different transition metals were used to modify V 2 O 5 -based catalysts (M-V, M = Cu, Fe, Mn, Co) on TiO 2 via impregnation, for the selective reduction of NO with NH 3 . The introduced metals induced high dispersion in the vanadium species and the formation of vanadates on the TiO 2 support, and increased the amount of surface acid sites and the strength of these acids. The strong acid sites might be responsible for the high N 2 selectivity at higher temperatures. Among these catalysts, Cu-V/TiO 2 showed the highest activity and N 2 selectivity at 225–375 °C. The results of X-ray photoelectron spectroscopy, NH 3 -temperature-programmed desorption, and in-situ diffuse reflectance infrared Fourier transform spectroscopy suggested that the improved performance was probably due to more active surface oxygen species and increased strong surface acid sites. The outstanding activity, stability, and SO 2 /H 2 O durability of Cu-V/TiO 2 make it a candidate to be a NO x removal catalyst for stationary flue gas.
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高影响因子
CHINESE JOURNAL OF CATALYSIS
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2015
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IF 1.964
Zhixin Zhang,Yehong Wang,Min Wang,Jianmin Lü,Lihua Li,Zhe Zhang,Mingrun Li,Jingyang Jiang,Feng Wang
We herein report the effects of CeO 2 crystal planes on the oxidative coupling of alcohols and amines to form imines. CeO 2 exhibits significant catalytic activity under mild reaction conditions (60 °C) during the synthesis of 13 different imines, giving >89% conversions and >90% selectivities. The crystal planes of CeO 2 greatly affect the catalytic performance. Among the crystal planes investigated (the (110), (100) and (111) planes), the (110) plane shows the strongest redox ability and thus the best catalytic activity, generating a 97% yield of the imine at 60 °C in 2 h, because it contains the highest concentration of oxygen vacancies.
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高影响因子
Journal of Energy Chemistry
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2015
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IF 2.352
Xinping Ouyang,Guodian Zhu,Xiangzhen Huang,Xueqing Qiu
The microwave assisted liquefaction process of wheat straw alkali lignin was investigated to obtain monophenolic compounds as the precursor of bio-fuel. It is found that the total yield of monophenolic compounds is significantly improved under microwave irradiation, reaching 15.77% under a relatively mild liquefaction condition of 10 wt% H 2 SO 4 as the catalyst, 10 wt% phenol as the hydrogen-donor reagent at 120 °C for 40 min. Compared with conventional thermal liquefaction process, microwave irradiation promotes the cleavage of C–C bonds, which gives an extra 29% of C aryl –C α bond cleavage , and increases the yield of monophenolic compounds from 0.92% to 13.61% under the same conditions. The excessive temperature and prolonged time under microwave irradiation will promote the recondensation of degraded lignin fragments, so the key to obtain high yield of monophenolic compounds is to avoid the recondensation reaction. The selected solid catalyst promotes the dissociation of methoxy groups, and the addition of phenol into liquefaction can only slightly improve the yield of monophencolic compounds.
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高影响因子
Journal of Energy Chemistry
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2015
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IF 2.352
Guiquan Zhang,Xin Zhang,Ting Bai,Tengfei Chen,Wentao Fan
The coking kinetics and reaction-regeneration on Zn/HZSM-5 (Zn/HZ) catalyst in the conversion of methanol to aromatics were investigated. The highest initial benzene, toluene and xylene (BTX) yield of ca. 67.7% was obtained on fresh Zn/HZ catalyst, which showed the worst catalytic stability. The cycle of reaction-regeneration significantly modified the texture and acidity of Zn/HZ catalyst, which in turn affected its catalytic performance and coking behavior in methanol conversion to BTX. The residual carbon located on the surface of Zn/HZ catalyst led to the decrease of acid sites and the change on the acid sites distribution, which played an important roles on its activity and deactivation. It was found that the high B/L ratio and the low total acid sites concentration of the Zn/HZ catalyst favored to the high BTX yield and good catalytic stability in methanol conversion.
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高影响因子
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