MICROCHEMICAL JOURNAL
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2018
·
IF 2.746
Jianmei Cen,Songbo Wei,Haijun Nan,Jianqiao Xu,Zhoubing Huang,Shuqin Liu,Qingkun Hu,Jun Yan,Gangfeng Ouyang
3D graphene-carbon nanotubes (G-CNTs) composite with unique morphology and structure was prepared by one-step insertion of CNTs into graphene. Subsequently, the G-CNTs composite as a fiber coating material for solid-phase microextraction (SPME) was fabricated on the surface of a stainless steel wire by direct coating method. The prepared coating was tested by the extraction of benzene homologues (BTEX, benzene, toluene, ethylbenzene and m-xylene). Compared with a commercial polydimethylsiloxane (PDMS) fiber, the home-made coating exhibited higher extraction performance for BTEX, and the reasons were discussed systematically. Under the optimized conditions, the prepared coating coupled with chromatography-mass spectrometry (GC–MS) for the analysis of BTEX exhibited wide linear ranges, low limits of detection (3 S/N) (LODs, 0.59–2.68 ng L −1 ), low limits of quantification (10 S/N) (LOQs, 1.96–8.92 ng L −1 ), good repeatability (3.2–5.5%, n = 6) and reproducibility (3.7–9.1%, n = 3). Finally, the developed method was successfully applied to the analysis of BTEX in environmental water samples with satisfactory recoveries (84.7–108.1%). This study is expected to further the exploration of high-performance SPME coating materials, and broaden the applications of graphene-based materials.
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Molecular Catalysis
·
2018
·
IF 0
Benhua Huang,Chao Fan,Heng Yu,Jinyi Ma,Cheng Pan,Donghua Zhang,Aqun Zheng,Yu Li,Yang Sun
Two palladium-containing silicates are prepared through sol-gel, and doping of L-sodium lactate plays a key role for giving helical morphology. The helical silicate is modified by chiral sulfonyl chloride in order to modulate coordination environment of palladium for enhanced catalysis. The porosity, composition, crystalline nature and bulk chirality have been studied too. All synthetic silicates show high yields for nitration of arenes by using available nitro-source. Both solvent acidity and oxidant seem crucial to nitration more than others. The conversion of larger arene is related to catalyst porosity, and modification of silicate with chiral sulfonyl chloride shows varied results. Furthermore, two catalysts exhibit renewable recycling behaviors, proving their interior palladium could be utilized. Lastly, a tetravalent palladium-facilitated mechanism is proposed. This wok may contribute to the design and catalytic application of nanosized or microsized silica material with particular morphology.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2019
·
IF 4.182
Yeqing Wang,Jian Zhang,Xiangju Meng,Shichao Han,Qiuyan Zhu,Na Sheng,Liang Wang,Feng-Shou Xiao
In this work, we show sustainable and efficient synthesis of nanosized EMT zeolite under organotemplate-free and solvent-free conditions, which not only completely avoids the use of organic templates for production of NOx and CO 2 but also effectively reduces the formation of polluted water. In addition, the yield of EMT zeolite is significantly enhanced by this route, compared with conventional hydrothermal synthesis . The nanosized EMT zeolite obtained has good crystallinity, uniform crystal size distribution, and high surface area. Ion-exchange tests show that the nanosized EMT zeolite owes high Ca 2+ and Mg 2+ ion exchange capacity at room temperature, which is potentially important for softening hard water in the industrial processes. Catalytic tests in Knoevenagel condensation show that the nanosized EMT zeolite exhibits higher activity than that of the EMT zeolite synthesized using organic template, indicating the importance of the nanosized EMT zeolite as a base catalyst.
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Journal of Inorganic and Organometallic Polymers and Materials
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2019
·Vol. 30
·期 3
·859-868
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IF 1.637
Cheng Lingping,Cai Jianfeng,Ke Yanxiong
Core–shell particles (CSPs), also known as superficially porous particles or fused-core particles, consisting of a solid core and a porous shell, have emerged as an advanced technology in high-performance liquid chromatography (HPLC). We report here an ultrasonic-assisted sol–gel method for the fabrication of CSPs with uniform mesoporous silica shell using tetraethoxysilane as the silica source and dodecylamine as a catalyst, template and porogen agent in a methanol–water solution. Instead of stirring, sonication was adopted to guarantee the particles monodispersity and uniformity. The shell thickness between 300 and 700 nm could be obtained by adjusting the sonication time and the volume ratio of methanol–water. Pore sizes from 3.4 to 8.5 nm were tuned by hydrothermal treatment. The C18-bonded 2.7 μm CSPs with a shell thickness of ~ 500 nm showed some advantages over a commercial 1.7 μm BEH column, and successfully applied for the analyses of a Chinese medicine and peptides. The CSPs could be a promising candidate as HPLC packing materials.
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TALANTA
·
2019
·
IF 4.916
Xiaohui Yang,Guangping Wan,Shujuan Ma,Hongjun Xia,Jun Wang,Jiawei Liu,Yanna Liu,Gang Chen,Quan Bai
Recently, superficially porous particles (SPPs) have been intensively studied and employed for highly efficient and fast separations. In this paper, the SiO 2 @SiO 2 SPPs were synthesized by an improved polymerization-induced colloid aggregation (PICA) method using urea-formaldehyde polymer as the template. The agglomeration of silica core during modification with ureidopropyltrimethoxysilane (UPS) can not only be avoided by reflux in neutral ethanol solution, but also the secondary nucleation of the colloidal silica sol can be inhibited via optimizing the reaction conditions including pH, temperature, colloidal silica sol concentration and the reaction time. The shell thickness and pore size of SPPs can be controlled successfully by adjusting the weight ratio of silica core/colloidal silica sol and the particle size of colloidal silica sol, respectively. The SPP-C18 columns packed using octadecyltrichlorosilane (ODS) modified SPPs with different pore sizes were employed to separate small solutes and proteins. The baseline separations of 6 kinds of alkyl benzenes and 5 kinds of aromatic alcohol homologues were achieved within 4 min by the SPP-C18 column with 8 nm pore size. Compared with the commercial BEH-C18 column, more than 50,000/m of the plate number of propylbenzene was obtained, and the former provided higher column efficiency to separate small solutes than the latter. Meanwhile, 6 kinds of proteins were also separated completely within 2 min using the SPP-C18 column with 40 nm pore size. In addition, the SPP-C18 capillary column was applied to separate and identify the BSA/HeLa/mouse liver digests with capillary LC-MSMS, respectively. The results indicate that more proteins and peptides can be identified using SPP-C18 capillary column compared with commercial silica-C18 capillary column. The result demonstrates that the prepared SPP-C18 column provides higher column efficiency and the SPPs synthesized with the improved PICA method shows a great potential application for the fast separation of small solutes and proteins.
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JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
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2017
·Vol. 93
·期 5
·1347-1358
·
IF 3.135
Yu Shen,Fumin Wang,Zongzhuang Han,Xubin Zhang
BACKGROUND ZSM-5 zeolites are of great importance in industrial catalysis. However, the diffusion limitations caused by small pore opening restrict the extent of catalytic conversions over conventional ZSM-5. Many studies have shown that mass transfer in zeolite channels can be improved by controlling the morphology or creating additional mesoporosity. Here, the catalytic performance is further improved by the creation of hollow structure and intracrystalline mesopores in ZSM-5 zeolite. RESULTS The characterization results demonstrated that hollow ZSM-5 with intracrystalline mesopores can be synthesized by using a simple one-step hydrothermal strategy with a commercial gemini-type cationic surfactant containing hydrophilic hydroxyl groups. Compared with the Fe-substituted conventional ZSM-5, the Fe-substituted hollow ZSM-5 with intracrystalline mesopores show remarkably enhanced catalytic performance in the hydroxylation of phenol. About 52.2% conversion of phenol can be obtained with almost 96.8% selectivity to dihydroxybenzenes. The catalytic activity remained almost unchanged after five cycles. CONCLUSION The newly created hollow structure and intracrystalline mesopores in ZSM-5 zeolite showed enhanced catalytic activity and reusability for the hydroxylation of phenol, which is higher than most reported systems. The prepared catalyst is a promising alternative material for the hydroxylation of phenol. © 2017 Society of Chemical Industry
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ENERGY & FUELS
·
2017
·
IF 3.091
Xuejiao Sun,Daofei Lv,Yongwei Chen,Ying Wu,Qihui Wu,Qibin Xia,Zhong Li
Chromium-based MIL-101 and graphite oxide (GO) composite (MIL-101@GO) was synthesized and applied for adsorption performances toward a series of aromatics (benzene, toluene, and ethylbenzene). Desorption activation energies of aromatics on this composite were evaluated based on temperature-programmed desorption (TPD) experiments. The results indicated that the aromatic uptakes on the composite increase with the carbon number at low pressure. In contrast, at high pressure, their adsorption capacities exhibit an opposite trend. The composite possesses high uptakes of the aromatics, which are approximately 1.8–6.0 times higher compared with conventional adsorbents. The desorption activation energies of the aromatics increase with the carbon number of aromatics. Additionally, the adsorption of ethylbenzene on the composite is highly reversible. More importantly, the MIL-101@GO composite exhibits enhanced thermal conductivity up to 0.369 W/mK at 303 K. The MIL-101@GO composite with high adsorption capacity, enhanced thermal conductivity, and efficient recyclability provided a promising candidate for practical applications in field of volatile organic compounds adsorption.
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ELECTROPHORESIS
·
2017
·Vol. 39
·期 2
·363-369
·
IF 2.744
Deying Kong,Zilin Chen
Pillar[ n ]arenes have achieved much interest in material chemistry and supramolecular chemistry due to unusual pillar shape structure and high selectivity toward guest. However, pillar[ n ]arenes have not yet been applied in capillary electrochromatography. This work at first time reports that carboxylatopillar[5]arene is used as a stationary phase in open-tubular capillary electrochromatography. Carboxylatopillar[5]arene not only possess the advantages of pillar[ n ]arenes but also provide free carboxy groups for immobilizing on the inner wall of capillary column via covalent bonding. The characterization of SEM and FT-IR indicated that carboxylatopillar[5]arene was successfully grafted on the inner wall of capillary. The baseline separation of model analytes including neutral, basic, and acidic compounds, nonsteroidal anti-inflammatory drugs and dansyl-amino acids have been achieved thanks to the electron-rich cavity of carboxylatopillar[5]arene and hydrophobic interactions between the analytes and stationary phase. The intraday, interday, and column-to-column precisions (RSDs) of retention time and peak area for the neutral analytes were all less than 3.34 and 9.65%, respectively. This work indicates that pillar[ n ]arenes have great potential in capillary electrochromatography as novel stationary phase.
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JOURNAL OF POROUS MATERIALS
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2024
·
IF 2.5
Zhang Yanting
Both seed solution and Cetyltrimethylammonium bromide(CTAB) serve as common template agents in the synthesis of hierarchical ZSM-5 zeolites. However, their specific roles in the synthesis process have not been clearly understood. In this study, hierarchical ZSM-5 zeolites were successfully synthesized using a 1.5% mass fraction (relative to the silicon source) seed solution in combination with varying amounts of CTAB. The physical and chemical properties of the hierarchical ZSM-5 zeolites were characterized using X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), low-temperature N 2 adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TG), ammonia temperature-programmed desorption (NH 3 -TPD), pyridine-IR, and 2,4,6-collidine-IR. The investigation revealed that the CTAB content significantly influenced the synthesis of hierarchical ZSM-5 zeolites, with CTAB contributing to framework filling, charge balancing, and acting as a mesoporous template during the synthesis process, while the seed solution primarily served as a structure-directing agent. Moreover, utilizing the conversion of C8 aromatic hydrocarbons as a probe reaction, it was demonstrated that ZSM-5 zeolites synthesized with the co-assistance of seeds and CTAB exhibited enhanced conversion for ethylbenzene and m-xylene compared to samples synthesized exclusively with a seed solution.
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MICROCHEMICAL JOURNAL
·
2025
·
IF 5.1
Zhen Zhang,You Wang,Xueqi Li,Xinran Wu,Yunyi Hu,Rong An,Ling Xu,Xiangdong Qing
In the contribution, a novel chemometric coupling technique combined with high-performance liquid chromatography with diode array detector (HPLC-DAD) was developed for the rapid quantification and source apportionment of eight monoaromatic hydrocarbons (MACHs) in soil samples. The strategy was built on the three-dimensional calibration based on alternating trilinear decomposition coupling with the unsupervised classification using t-distributed stochastic neighbor embedding (named ATLD-t-SNE). Firstly, a validation set and a spiked soil set were used to investigate the quantitative performance of the developed method. The obtained average recoveries of eight MACHs in soil samples were between (95.0 ± 4.4)% and (111.9 ± 3.3)%, and the limits of detection ranged from 0.0041μg mL −1 to 1.85 μg mL −1 , which were better than the results of parallel factor analysis-alternating least squares (PARAFAC-ALS). Subsequently, the proposed approach was applied to analyze actual soil samples collected from tea plantations (7 samples) and industrial areas (60 samples), revealing the presence of ethylbenzene (EBZ) and (1,3,5)-trimethylbenzene (MTY) in both types of soil samples, could the absence of other six MACHs. Finally, ATLD-t-SNE was utilized to classify these soil samples and a comparison between the new strategy and ATLD combined with feature component analysis as well as principal component analysis (called ATLD-FCA and ATLD-PCA, respectively) was made. The finding indicated that ATLD-t-SNE provided better clustering than other two methods, indicating different sources of organic pollution of MACHs in soil samples.
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CATALYSIS SURVEYS FROM ASIA
·
2024
·
IF 2.1
Zhou Hantao,Feng Shangzhen,Yang Jie,Jiang Huanjin,Zhang Xing,Chen Jixiang
Zeolites (Hβ, HZSM-5 and HM), TiO 2 and ZrO 2 supported NiCo alloy catalysts were tested for the hydrodeoxygenation of phenol in aqueous phase. It has been found that the catalyst acidity remarkably influences the catalyst activity and the product distribution. Zeolites supported catalysts give much higher yield of the deoxygenated products (mainly benzene and cyclohexane) than NiCo/TiO 2 and NiCo/ZrO 2 , where cyclohexanol and cyclohexanone are dominating. Associated with NH 3 -TPD, we suggest that the catalyst acidity promotes the hydrodeoxygenation. Hβ zeolite supported NiCo alloy is more active than others, attributed to its higher metal dispersion and more acid sites. Therein, the Hβ zeolite calcined at 750 o C has moderate acidity, and its supported NiCo alloy catalyst (NiCo/HB-750) shows the best performance. Under a suitable reaction condition, the phenol conversion and the total yield of deoxygenated products reaches 96.8% and 94.5% on NiCo/HB-750, respectively.
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ANALYTICAL CHEMISTRY
·
2015
·
IF 5.636
Jun-Hui Zhang,Sheng-Ming Xie,Ling Chen,Bang-Jin Wang,Pin-Gang He,Li-Ming Yuan
Porous organic molecular cages as a new type of porous materials have attracted a tremendous attention for their potential applications in recent years. Here we report the use of a homochiral porous organic cage (POC) (CC3-R) diluted with a polysiloxane (OV-1701) as a stationary phase for high-resolution gas chromatography (GC) with excellent enantioselectivity. A large number of optical isomers have been resolved without derivatization, including chiral alcohols, diols, amines, alcohol amines, esters, ketones, ethers, halohydrocarbons, organic acids, amino acid methyl esters, and sulfoxides. Compared with commercial β-DEX 120 and Chirasil-L-Val columns, the CC3-R coated capillary column offered more preeminent enantioselectivity. In addition, CC3-R also exhibits good selectivity for the separation of isomers, linear alkanes, alcohols, and aromatic hydrocarbons. The excellent resolution ability, repeatability, and thermal stability make CC3-R a promising candidate as a novel stationary phase for GC. The study described herein first proves useful commercially. This work also indicates that porous organic molecular materials will become more attractive in separation science.
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