MICROPOROUS AND MESOPOROUS MATERIALS
·
2018
·
IF 3.649
Qingqing Ma,Nan Wang,Guozhu Liu,Li Wang
Pd catalysts on mesoporous silica SBA-15 functionalized with alkyltriethoxysilane (alkyl = methyl, ethyl, propyl and isobutyl) were prepared. The effects of grafting sequence on the grafting amount were studied. The catalysts were characterized by XRD , FT-IR, elemental analysis , thermogravimetric analysis , nitrogen adsorption-desorption, TEM and XPS , and evaluated using catalytic hydrogenation of 2-ethyl-anthraquinone. The grafting amount increases with increasing the alkyl chain length of alkyltriethoxysilane. The highest grafting amount with the carbon content of 1.56% is obtained using an ante-grafting procedure where the grafting is performed prior to the removal of template, and this catalyst shows the highest activity and selectivity (98.3%). The accordant relationship between the activity of Pd/SBA-15 catalysts and their grafting amount indicates a positive effect of hydrophobicity of SBA-15 created by grafting on the catalytic hydrogenation of 2-ethyl-anthraquinone.
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高影响因子
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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高影响因子
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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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 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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MICROPOROUS AND MESOPOROUS MATERIALS
·
2015
·
IF 3.453
Hui-Min Zhao,Chang-Miao Di,Lan Wang,Yuan Chun,Qin-Hua Xu
Mesoporous graphitic C 3 N 4 has been synthesized using a novel cross-linked bimodal mesoporous (CLBM) SBA-15 as a hard template. This cross-linked bimodal mesoporous SBA-15 template was prepared by adjusting the pH to alter the copolymer micelle size. The resulting mesoporous g -C 3 N 4 replicates the morphology of the mesoporous silica template, and numerous pore openings are formed on the surfaces. The mesoporous g -C 3 N 4 exhibits a high specific surface area and a large pore volume . The photocatalytic degradation activity of methyl orange on mesoporous g -C 3 N 4 is nearly 15.3 times as high as that on bulk- g -C 3 N 4 under visible light irradiation. The high photocatalytic performance of this sample is due to the high specific surface area and more readily accessible active sites.
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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
CHEMICAL ENGINEERING JOURNAL
·
2015
·
IF 4.321
Xianxiang Liu,Jiafu Xiao,Hui Ding,Wenzhou Zhong,Qiong Xu,Shengpei Su,Dulin Yin
Amino modified SBA-15 (SBA-NH 2 ) was used to immobilize vanadyl (VO 2+ ) and cupric (Cu 2+ ) ions, giving SBA-NH 2 -VO 2+ and SBA-NH 2 -Cu 2+ catalysts, respectively, and the as-prepared catalysts were characterized by XRD, XPS, TEM and Nitrogen adsorption–desorption technologies. The catalytic performance of the SBA-NH 2 -VO 2+ catalysts for the oxidation of HMF can be enhanced by the use of SBA-NH 2 -Cu 2+ as the co-catalyst. Several important reaction parameters were investigated, and it was found that the reaction solvent showed a great effect on the oxidation of HMF. The highest HMF conversion and product selectivity were obtained in aromatic solvents. The highest HMF conversion reached 98.8% at 110 °C in 4-chlorotoluene, affording DFF and 2,5-furandicarboxylic acid (FDCA) with yields of 28.9% and 62.7%, respectively. More importantly, the catalysts could be recycled and showed no significant decrease of their catalytic activities.
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JOURNAL OF MATERIALS CHEMISTRY
·
2011
·Vol. 22
·期 5
·2263-2270
·
IF 5.101
Qi Zheng,Yongheng Zhu,Jiaqiang Xu,Zhixuan Cheng,Huimin Li,Xinxin Li
Two new mesoporous SBA-15/organic hybrids featuring fluoroalcohol and fluorinated-phenol derivatives were successfully synthesized via a co-condensation route. Hexafluorobisphenol and hexafluoroisopropanol were chosen to graft onto mesostructured silica, respectively. The as-synthesized hybrids preserve their mesoscopic structures with relative large surface areas and pore volume, as confirmed by SAXS, TEM and N2 adsorption–desorption porosimetry. Moreover, FT-IR and solid-state MAS NMR spectroscopy proved covalent anchoring of the organic functional groups onto the SBA-15. In order to confirm the potential application of the hybrids in gas sensing, investigations on the sensing properties toward the nerve agent simulant dimethyl methylphosphonate (DMMP) were carried out by QCM transducer. The QCM sensors based on hybrid materials exhibit excellent sensitivity toward trace DMMP vapour down to 26 ppb. In comparison with pristine SBA-15, the hybrids also show remarkably enhanced selectivity to DMMP due to suitable H-bonding interactions. Therefore, the well-defined mesoscopic porosity of the organic–inorganic hybrids together with the grafted fluoroalcohol and fluorinated-phenol derivatives lead to excellent sensing properties to DMMP vapour, and show great potential in the area of nerve agent detection.
研究领域:
材料科学
·
化学传感器
·
无机化学
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分析化学
·
纳米材料
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JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY
·
2024
·Vol. 333
·期 3
·1343-1356
·
IF 1.5
Bi Dongxu,Cai Weiqian,Xiong Lingshan,Luo Qie,Wang Youqun,Zhang Zhibin,Xu Lin,Cao Xiaohong,Liu Yunhai
Three types of magnetic mesoporous silicas (MMSs), namely, MMCM-41, MMCM-48 and MSBA-15 were prepared by a hydrothermal method using CTAB and P123 as templates. The structure and physicochemical properties of MMSs were characterized by small angle XRD, VSM, ζ potential analyzer, contact angle measurer, and XPS, etc. The potential applications of MMSs in U(VI) recovery were thoroughly investigated. The adsorptive kinetics, thermodynamics, and selectivity of MMCM-41, MMCM-48 and MSBA-15 were compared. The results show that MSBA-15 revealed a high capacity for U(VI) (341.94 mg·g −1 ) and a superior selectivity than MMCM-41 and MMCM-48. The adsorption mechanism was explored by using the relevant adsorption models and XPS. The results indicated that MSBA-15 could be considered a strong candidate for the adsorption and recovery of U(VI) from radioactive wastewater.
研究领域:
环境科学
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材料科学
·
化学工程
·
核技术
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高影响因子
MATERIALS RESEARCH BULLETIN
·
2013
·
IF 1.913
Peng Dai,Lili Zhang,Guang Li,Zhaoqi Sun,Xiansong Liu,Mingzai Wu
Different loadings of SnO 2 nanoparticles embedded in mesoporous silica (SBA-15) were prepared via a two-solvent method with the ordered hexagonal mesoporous structure of SBA-15 kept. X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy and N 2 adsorption porosimetry were employed to characterize the nanocomposites. Compared with pure SnO 2 nanoparticles, the SnO 2 /SBA-15 nanocomposites show higher response to H 2 at lower operating temperature. The photocatalytic activity of as-prepared SnO 2 /SBA-15 for degradation of methylene blue was investigated under UV light irradiation and the results show that the SnO 2 /SBA-15 nanocomposites have higher photodegradation ability toward methylene blue than pure SnO 2 nanoparticles.
研究领域:
材料科学
·
纳米科技
·
环境催化
·
传感器技术
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