THERMOCHIMICA ACTA
·
2013
·
IF 1.989
Li Yin,Defeng Wu,Zhen Yao,Saihua Feng,Ming Zhang,Yufang Gao
Poly(trimethylene terephthalate)/mesoporous silica SBA-15 composites were prepared by in situ hybridization for the crystallization study. The results show that SBA-15 particles are well compounded with PTT, forming nanostructured composite system. Although the addition of SBA-15 particles results in an evident decrease of PTT molecular weight, those well dispersed mesoporous particles can compensate effectively for the property degradation of PTT. Besides, the addition of SBA-15 particles has large influence on the crystallization of PTT. The composites show higher crystallization temperature and rate than that of the neat PTT. But the presence of SBA-15 impedes PTT chain segment movements somewhat. In comparison with neat PTT, therefore, the composites present lower folding surface free energy and higher diffusion activation energy. The kinetic analysis results elucidate that the crystallization rate of PTT is dominated by the nucleation item instead of the growth one.
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高影响因子
CARBOHYDRATE POLYMERS
·
2014
·
IF 3.916
Guozhi Fan,Chongjing Liao,Tao Fang,Shanshan Luo,Guangsen Song
The acetylation of cellulose using sulfonated Amberlyst 15 as a new and reusable catalyst was investigated. Optimization of the acetylation process was carried out by variation in the amount of added catalyst, acetic acid, and acetic anhydride as well as the reaction conditions, which includes reaction time and reaction medium. Cellulose acetate, with a degree of substitution (DS) value of 2.38 and yield of 54.1%, was obtained under the optimized conditions and characterized using Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis–derivative thermogravimetry (TGA–DTG), and differential scanning calorimetry (DSC). The sulfonated polymer catalyst could be easily recovered by centrifugation after acetylation. Both the fresh and recovered catalysts were characterized by means of FTIR, TGA–DTG, DSC, and scanning electron microscopy (SEM), and the recovered catalyst could be successfully reused without further treatment. It was found that Amberlyst 15 possessed excellent catalytic stability, no significant changes in the DS values, and consistent yields of cellulose acetate observed over four reaction cycles.
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DOI
PubMed
高影响因子
JOURNAL OF SUPERCRITICAL FLUIDS
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2014
·
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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RSC Advances
·
2016
·Vol. 6
·期 52
·46908-46914
·
IF 3.289
Lixin Xu,Bo Jin,Jian Zhang,Dang-guo Cheng,Fengqiu Chen,Yue An,Ping Cui,Chao Wan
Bimetallic AgPd nanoparticles were successfully immobilized on graphitic carbon nitride (g-C3N4) functionalized SBA-15 for the first time by a facile co-reduction method. These catalysts were applied in the decomposition of formic acid. The dehydrogenation of formic acid is dependent on the composition of AgPd and the content of carbon nitride (CN). Among all of the AgPd/mCND/SBA-15 catalysts tested, the Ag10Pd90/0.2CND/SBA-15 catalyst exhibits highly superior performance for the decomposition of formic acid into high-quality hydrogen at 323 K with 100% hydrogen selectivity and a turnover frequency of 893 h−1, which is among the maximum values obtained at 323 K in this paper. The improved performance is a promising step towards the utilization of formic acid as a hydrogen storage material.
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ChemCatChem
·
2016
·Vol. 8
·期 6
·1199-1207
·
IF 4.724
Lan-Lan Lou,Shanshan Li,Huanling Du,Jiong Zhang,Wenjun Yu,Kai Yu,Shuangxi Liu
Graphical Short support : A short-mesochannel SBA-15 material is applied to the immobilization of a chiral 9-amino epicinchonine iridium catalyst, which exhibit excellent catalytic activity and notably improved enantioselectivity for the asymmetric transfer hydrogenation of aromatic ketones. A short-mesochannel SBA-15 material functionalized with propylthiol groups was prepared by co-condensation and applied to the immobilization of chiral 9-amino epicinchonine. After complexing with [Ir(cod)Cl] 2 (cod=1,5-cyclooctadiene), these mesoporous materials were evaluated as catalysts for the asymmetric transfer hydrogenation of aromatic ketones. Higher enantioselectivities and comparable, or even higher, catalytic activities were achieved compared with the free catalyst. Both the short mesochannel and co-condensation approach for short-mesochannel SBA-15 materials functionalized with propylthiol groups, [SSBA-SH( x )] materials were demonstrated to contribute to the excellent catalytic performance. In addition, the catalyst SSBA-AEC(5)/Ir (AEC=9-amino epicinchonine), with low 3-mercaptopropyltrimethoxysilane (MPTMS) content, showed the best catalytic performance; a high enantiomeric excess of 84 % (homogeneous ee =60 %) along with a conversion of 97 % was achieved within 1 h for asymmetric transfer hydrogenation of acetophenone. Moreover, these immobilized catalysts showed high stability during the reaction and could be recovered for reuse.
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CATALYSIS TODAY
·
2016
·
IF 4.312
Yibo He,Qinghua Zhang,Xiaoli Zhan,Dang-guo Cheng,Fengqiu Chen
Friedel–Crafts alkylation of benzene with 1-dodecene, which is an important reaction of synthetic detergent, was studied via ionic liquid [bmim][TFSI]/AlCl 3 (1-butyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide/AlCl 3 ) immobilized on SBA-15 catalysts. XRD, BET, TEM, TG, ammonia TPD investigations were used to search insight into catalyst characteristic. The immobilized catalysts preserved ordered structure and presented high specific surface areas. The utilization of active sites was significantly improved by immobilization. Based on ammonia TPD, immobilized catalysts exhibited higher Lewis acidity than aluminum chloride grafted SBA-15. TG indicated that thermal stability of ionic liquid has been improved by immobilization. The influences of various reaction conditions including reaction time, benzene/1-dodecene ratio were studied. Immobilized ionic liquids have better performance of no matter 1-dodecene conversion or 2-linear alkyl benzene (2-LAB) selectivity, than bulk ionic liquid catalysts or aluminum chloride grafted mesoporous materials. 2-LAB selectivity can be increased from about 35% with bulk ionic liquid to more than 60% with immobilized catalysts. Under optimal condition, 2-LAB selectivity reached as high as 80%. The immobilized catalysts could be reused. And at 3th cycle of catalysts, 1-dodecene conversion could still reach more than 50%. The role of deactivation was proposed based on TEM, BET and TG investigations. By-products as oligomer , produced by oligomerization of olefin , blocked or covered the pores, led to deactivation of catalysts.
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RSC Advances
·
2016
·Vol. 6
·期 74
·70424-70432
·
IF 3.289
Ran Ji,Shangru Zhai,Wei Zheng,Zuoyi Xiao,Qingda An,Feng Zhang
Towards the aerobic oxidation of alcohols, palladium nanoparticle immobilized mesoporous catalysts have been extensively investigated; however, the preparation of efficient catalytic materials without using complexing moieties remains a challenge. Herein, a simple yet effective concept that directly utilizes inorganic ZrSBA-15, a mild acidic framework, as a supporting matrix for Pd NPs was applied. The catalysts were fully characterized using X-ray diffraction, N2 adsorption–desorption isotherms, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. It was demonstrated that, on the basis of these characterization results, active Pd NPs had been successfully loaded onto the porous framework of ordered ZrSBA-15. More significantly, the method of preparation was also attributed to the catalytic properties of the resultant sample, in which the interactions between Pd species and acidic framework were improved, leading to a uniform dispersion and enhanced stabilization of Pd particles. Meanwhile, Pd/ZrSBA-15 catalysts exhibited expected activity in the aerobic oxidation of benzyl alcohol with at least 95% conversion and 99% selectivity for benzaldehyde. Moreover, the oxidation reaction could be performed smoothly under solvent- and base-free conditions, and the catalyst was recycled several times with negligible loss in selectivity and conversion.
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Catalysis Science & Technology
·
2017
·Vol. 7
·期 23
·5540-5549
·
IF 5.773
Xinqiang Feng,Chun Shen,Kaiyue Ji,Jiabin Yin,Tianwei Tan
Mesoporous solid acid catalyst WO3/SBA-15 exhibited high performance for the production of bio-based p-xylene (PX). After immobilization on SBA-15, isolated [WO4]2− tetrahedral species which were coordinatively unsaturated, were generated and functioned as Lewis acid centers. The ratio of Lewis to Brønsted acid sites varied in the range of 7.4 to 13.4 by adjusting the calcination temperature. A high ratio of Lewis to Brønsted acid sites and the mesoporous structure contributed to the high activity and stability: a selectivity of 88.0% for PX with a conversion of 64.4% and a carbon balance of 90.1% was achieved over 0.20-WO3/SBA-15-700. Compared with microporous Sn-Beta, the as-prepared catalyst showed better resistance to carbon deposition with a 20% higher yield. The spent catalyst could be easily regenerated by calcination at high temperature. The conversion decreased by 3% and no loss in PX selectivity was observed after five regeneration cycles. The as-prepared WO3/SBA-15 catalyst is highly active, stable and recyclable, and has high potential towards bio-based PX production.
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JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2024
·
IF 3.5
Xiao-Chun Deng,Xiao-Dong Kang,Guo-Hua Zhang
The (TiZrHfNbTaMo)C-15 wt.% Co ceramics with excellent comprehensive properties were successfully prepared by vacuum liquid phase sintering. The effects of WC content on the grain size, microstructure, and mechanical properties were investigated. The results showed that WC was dissolved into (TiZrHfNbTaMo)C phase to form a seven-component solid solution, and the independent WC phase disappeared. The addition of WC improved the wettability between the ceramic phase and the metal phase and promoted the densification of the ceramics. In addition, WC played a role in refining grains and inhibiting the grains growth to a certain extent. The comprehensive properties of ceramics were improved by solid solution strengthening and high entropy effect. When the WC content was 5 wt.%, the toughness reached the maximum of 9.41 ± 0.15 MPa·m 1/2 , and the hardness of the ceramic with 10 wt.% WC achieved the highest value of 18.18 ± 0.20 GPa.
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MICROCHEMICAL JOURNAL
·
2025
·
IF 5.1
Su Han Wang,Min Lin,Jing Liu,Jian Ping Wang,Ning Peng Wu
The quinolone efflux pump (QepA) protein of a fluoroquinolones-resistant Escherichia coli was grafted on Fe 3 O 4 to synthesize a type of magnetic composite Fe 3 O 4 @QepA. This material was combined with 4 fluorescent tracers to develop a semi-homogeneous fluorescent array on 96-well microplate for determination of fluoroquinolones (FQs) in chicken, and the results were analyzed by using linear discriminant analysis method. Results showed this method could discriminatively determine 15 FQs at the concentration ≥10 ng/g, and could identify each drug species at the concentration ≥2 ng/g. The method exhibited satisfactory recoveries in chicken sample (61.7 %–119.8 %). The analysis results for some unknown samples were consistent with a liquid chromatography mass spectrometry method. This is the first paper reporting a semi-homogeneous fluorescent array for discriminative determination of small molecule substances, and this array can be used as an accurate tool to determine the 15 FQs in meat sample.
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高影响因子
Frontiers in Chemistry
·
2025
·
IF 4.2
Jinwei Li,Yifei Wei,Qiang Liu,Huanhuan Guan,Chengchun Jiang,Xiaohui Sun
In this study, CuO-CoOx/SBA-15 catalysts were successfully synthesized via ultrasonic impregnation, and their performance in degrading nitrobenzene within a Fenton-like system was investigated. The catalyst materials were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy (SEM), transmission electron microscope(TEM) and energy-dispersive X-ray spectroscopy (EDS). The CuO-CoOx/SBA-15 catalysts featured well-distributed CuO-CoOx nanoparticles within the mesoporous SBA-15 support. Compared to CuO/SBA-15 and Co3O4/SBA-15 catalysts with similar microstructures, the CuO-CoOx/SBA-15 catalysts exhibited Cu-Co dual active centers and a higher abundance of redox-active sites. During catalytic degradation, H2O2 was continuously activated on the catalyst surface through efficient Cu+/Cu2+ and Co2+/Co3+ redox cycles. The experimental conditions (initial pH, catalyst dosage, and H2O2 dosage) were optimized, resulting in 99% nitrobenzene removal over a wide pH range (3.0–9.0). The primary mechanisms for the oxidation and subsequent removal of nitrobenzene in the CuO-CoOx/SBA-15-H2O2 system were identified as reactions with hydroxyl radicals (·OH).
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PubMed
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Food Bioscience
·
2024
·
IF 4.8
Yuyang Zhang,Ting Feng,Xing Ni,Jiaojiao Xia,Hongbo Suo,Lishi Yan,Bin Zou
In this study, Candida rugosa lipase (CRL) was immobilized on the silica carrier SBA-15 by physical adsorption , then mixed with hydrophobically modified sodium alginate and dropped into calcium chloride solution. Finally, the adsorption-embedding immobilized lipase (L-SBA-15-Mgel) was successfully prepared. The conformation of the carrier before and after lipase immobilization were analyzed by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and other characterization techniques. The molecular docking and molecular dynamics simulation of CRL and modifier dodecyl glycidyl ether (DGE) ligand were carried out to analyze the potential influence of modifier on enzyme characteristics. The basic enzymatic properties including the activity, stability and reaction kinetic parameters of the immobilized lipase L-SBA-15-Mgel were studied. L-SBA-15-Mgel showed good storage stability and reusability. After 16 days of storage, the activity retention was 47.85%, and there was still 63.20% of the residual activity after seven cycles of reuse. The immobilized lipase was applied to the efficient synthesis of food flavor ester isoamyl acetate . Under the reaction conditions of 50 °C and 200 rpm, the highest yield of isoamyl acetate catalyzed by L-SBA-15-Mgel was 85.19%.
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