CHEMICAL ENGINEERING COMMUNICATIONS
·
2019
·
IF 1.431
Hong Yuan,Zhaoyang Dong,Jie He,Yunjie Wang,Hong Zhang
The solid acid catalysts SO42−/ZrO2 were prepared by impregnation technique at different calcination temperatures. The surface characterizations were carried out by using scanning electron microscope (SEM), Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), temperature programed desorption of NH3 (NH3-TPD), and N2-BET. The SEM results showed that the size of the SO42−/ZrO2 was not uniform and varied from about 1 to 20 µm. The characteristic peaks in FTIR spectra were essentially the same within the calcination temperature range of 400–700 °C. The XRD results indicated that the transition temperature from amorphous to tetragonal phase was up to 500 °C. The strong acid and superacid sites of the samples could be observed by the NH3-TPD results. The largest BET surface area was 140 m2/g, when the calcination temperature was at 500 °C, and all the pore size distributions belong to mesoporous range. The solid acid SO42−/ZrO2 was used for the epoxidation of castor oil. When the calcination temperature of SO42−/ZrO2 was 600 °C, reaction temperature 45 °C, and reaction time 8 h, the reaction effect was better with an iodine value of 33.0 ± 1.6 g/100 g and an epoxy value of 2.45 ± 0.11 mol/100 g.
研究领域:
材料科学
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催化化学
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DOI
高影响因子
CATALYSIS LETTERS
·
2019
·Vol. 150
·期 1
·209-221
·
IF 2.372
Xu Songlin,Zhang Mingyi,Guo Shujuan,Li Mengru,Huang Qingming,Chen Xiaohui
Abstract Diffusion limitation caused by microporous molecular sieves has always been a bottleneck problem in liquid phase epoxidation. In this study, several different carbon sources were used as hard templates to prepare hierarchically porous zeolite Ti-MWW (cTi-MWW) successfully. Compared with conventional Ti-MWW, cTi-MWW has an additional hierarchically porous structure and abundant pore structure distribution. Especially, the cTi-MWW prepared with polyethylene glycol1540 (PEG) as the hard template not only has a multiple hierarchically porous structure, but also exhibits small crystal size and good hydrophobicity properties studied by TEM and in situ FT-IR. At the same time, the cTi-MWW prepared with PEG exhibits better activity than the conventional Ti-MWW in the selective epoxidation reaction of allyl alcohol (AAL) with H 2 O 2 as oxidant and the conversion is improved by 11% (Si/Ti = 20). And a higher efficiency and longer catalyst life in fixed-bed catalytic reactor were exhibited by using cTi-MWW PEG as catalyst. The physicochemical properties of cTi-MWW prepared with different hard templates were systematically studied by SEM, XPS, UV–Vis, XRD and N 2 absorption–desorption techniques. This method is effective for the synthesis of cTi-MWW and significant for the preparation of hierarchically porous zeolites in industrial production. Graphic Abstract A hierarchically porous zeolite Ti-MWW prepared with different hard templates successfully. With the hierarchically porous structure, which have better adsorption, diffusion, and reactivity in liquid phase epoxidation, thus improving the catalytic activity. Especially, the hierarchically porous zeolite Ti-MWW prepared with polyethylene glycol exhibits small crystal size and good hydrophobicity properties.
研究领域:
材料科学
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催化化学
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DOI
高影响因子
EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY
·
2015
·Vol. 117
·期 8
·1185-1191
·
IF 1.812
Weiwei Cheng,Guoqin Liu,Xuede Wang,Xinqi Liu,Lu Jing
In this work, the kinetics of “in situ” epoxidation of soybean oil with H 2 O 2 (30% w/w), catalyzed by phosphotungstic heteropoly acid [π-C 5 H 5 N(CH 2 ) 15 CH 3 ] 3 [PW 4 O 16 ] (PHA) phase transfer catalyst and polyethylene glycol (PEG) as interfacial agent in dichloroethane, were investigated at 40, 50, 60, and 70°C. Assuming that the epoxidation reaction occurred in the pseudo-homogeneous catalytic system and the side reaction of epoxy ring cleavage was negligible, the results appeared that the epoxidation reaction of soybean oil in the presence of PEG was a second-order with respect to double bond concentration and a first-order to the H 2 O 2 concentration. The corresponding apparent activation energy (42.12 kJ/mol) was lower than that of PHA alone (49.23 kJ/mol), indicating that PEG could decrease the activation energy and speed up the epoxidation reaction of soybean oil. Practical applications: An environmentally friendly catalyst is eagerly needed to produce peroxided soybean oil for low yield and to prevent polluting the environment through the epoxidation of soybean oil with peracid. Phosphotungstic heteropoly acid phase transfer catalyst and polyethylene glycol improve the conversion and selectivity of the epoxidation reaction of soybean oil, and enhance its production efficiency. The activation energy of the soybean oil epoxidation reaction with H 2 O 2 catalyzed by phosphotungstic heteropoly acid (PHA) in the presence of polyethylene glycol (PEG) was lower than that of PEG alone, accounting for the results showing that the epoxy group band of the former (PHA + PEG) appeared quicker than the latter (PHA) in IR spectra.
研究领域:
化学工程
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催化化学
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DOI
高影响因子
ACS Omega
·
2020
·
IF 2.87
Shujuan Guo,Yanjie Zhang,Yuansong Ye,Jinzhe Song,Mengru Li
Synthesis of a Ti-incorporated zeolite using a simple and economical method has recently become a focus of attention. The direct hydrothermal synthesis of Ti-MWW is most commonly applied; however, it is challenging to perform and exhibits low titanium utilization. An innovative strategy of synthesizing Ti-MWW is proposed in the present study by simply treating the ERB-1 precursor of an MWW-type boron silicate with a H2TiF6/HNO3 solution. This significantly shortens the Ti grafting process from 5 days to only a few hours and reduces the use of the structure-directing agent hexamethyleneimine (HMI); furthermore, no extraframework Ti is observed in the precursor, indicating good atomic economy. Typically, a piperidine (PI)-treated sample Ti-MWW2–1-PI exhibits a higher conversion (76.6%) than the original Ti-MWW (44.8%) in the epoxidation of 1-hexene. X-ray diffraction (XRD), inductively coupled plasma (ICP), and transmission electron microscopy (TEM) techniques are used to explain in detail the probable mechanism underlying the incorporation of Ti species into the MWW framework. X-ray photoelectron spectroscopy (XPS) is employed to study the coordinate state of the Ti and F species in the samples after treatment with a piperidine solution. This method can be applied to synthesize other kinds of lamellar-structured zeolites with heteroatoms.
研究领域:
催化化学
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材料科学
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DOI
PubMed
高影响因子
Journal of Materials Chemistry A
·
2022
·Vol. 10
·期 10
·5540-5549
·
IF 14.511
Zixuan Xu,Ke Liu,He Huang,Yadong Zhang,Zhouyang Long,Minman Tong,Guojian Chen
In this work, we reported a facile catalyst-free and initiator-free strategy to fabricate a new class of viologen-linked ionic polyacetylenes (denoted as VIPAs) that can achieve simultaneous ionization and polymerization in one-pot and one-step. To our surprise, the ionic polymers VIPA-X (X = Br or Cl) were directly synthesized by quaternization-induced in situ polymerization from commercially available 4,4′-bipyridine with propargyl bromide or propargyl chloride. It was found that reaction temperatures have a remarkable influence on the synthesis of VIPAs, achieving the transformation from soluble oligomers to insoluble highly cross-linked polymers by adjusting the temperatures from 30 °C to 100 °C. At a higher temperature of 100 °C, the obtained highly cross-linked ionic polymers VIPA-Br and VIPA-Cl were insoluble in both hot water and even dimethyl sulfoxide (DMSO). By virtue of abundant halogen anions and the absorbed H-bonded water, both VIPA-Br and VIPA-Cl were employed as efficient heterogeneous catalysts for the conversion of CO2 with various epoxides into cyclic carbonates at atmospheric pressure and low temperatures. In particular, the catalytic activities of VIPA-Br for the conversion of various epoxides are much better than those of VIPA-Cl at low temperatures, which should be attributed to the higher nucleophilicity and better leaving ability of the Br− anion than those of the Cl− anion. The present work affords a succinct catalyst-free strategy to construct more task-specific ionic polyacetylenes by quaternization-induced polymerization of multi-N-heterocycle monomers and propargyl halides towards diverse applications.
研究领域:
材料科学
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催化化学
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环境科学
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DOI
高影响因子
TALANTA
·
2023
·
IF 6.1
Jian Zhang,Qingce Zang,Wei Xu,Fei Tang
Unsaturated lipids play an essential role in living organisms, and their different isomers show significant functional differences. Therefore, in situ characterization of unsaturated lipids in tissues needs to be extended to isomer level. However, the exposure of tissue sections to an open environment for a long time may cause cell autolysis or corruption, and current unsaturated lipid imaging methods still face challenges in efficiency. This paper proposes an imaging method based on photoepoxidation coupled with air-flow-assisted desorption electrospray ionization mass spectrometry (AFADESI-MS) to rapidly realize the spatial characterization of unsaturated lipids at the isomer level. The technique has a fast response speed, high epoxide yield (>80%), and high diagnostic ion abundance. After 0.5 min of photoepoxidation, the derivation product yield ratio reached 24.6%. This method rapidly identified six glycerophospholipid isomers containing an 18:1 acyl chain in normal rat liver tissue. Then the imaging method was applied in nude mice lung cancer tissue and human thyroid cancer tissue, with only 3 min photoepoxidation. Results successfully characterized the location and range of unsaturated lipid isomers and revealed their enrichment in tumor tissue. In addition, the experiment shows that the variational trend of the ratio of unsaturated lipid isomers in different types of tumor samples is different. Based on the advantages of efficiency and convenience, this method is prospective for screening unsaturated lipid markers and pathological research of related diseases.
研究领域:
生物化学
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医学影像学
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病理学
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DOI
PubMed
高影响因子
Journal of Bioresources and Bioproducts
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2020
·
IF 0
Guodong Feng,Yan Ma,Meng Zhang,Puyou Jia,Chengguo Liu,Yonghong Zhou
Waste cooking oil was modified to prepare bio-base plasticizers (a, b and c) with terephthalic acid, adipic acid and benzoic acid by transesterification, epoxidation and ring opening reactions, respectively. The polyvinyl chloride (PVC) films (a/PVC, b/PVC and c/PVC) were prepared using a, b and c as bio-base plasticizers. The epoxidation and ring opening reactions were mainly investigated through GC-MS analysis. The structures of bio-base plasticizers (a, b and c) were confirmed by Fourier transform infrared spectroscopy (FT-IR), 1 H NMR and 13 C NMR. The mechanical properties of a/PVC were as good as those of PVC films with the dioctyl phthalate (DOP) plasticizer. Meanwhile, the elongation at break of c/PVC reached 422%. The glass transition temperature ( T g ) from dynamic mechanical analysis (DMA) was reduced to 30.6˚C, 45.3˚C, 23.6˚C and 40.6˚C, respectively when 40 phr of a, b, c and DOP plasticizer were added. Results of thermogravimetric analysis (TGA) illustrated that the thermal degradation stabilitiy of a/PVC films was better than those of c/PVC and DOP/PVC. The volatility losses of a, b and c were lower than that of the DOP. Bio-base plasticizers a and c exhibited excellent migration resistance in different solutions (distilled water, 50% ethanol (w/w)). The FT-IR of PVC films showed that the downfield shifts of the —CH—Cl groups of the PVC plasticized with a and c were greater than that of b/PVC. The bio-base plasticizers b had a better plasticizing effect at low temperature.
研究领域:
材料科学
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环境科学
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化学工程
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DOI
Materials Research Express
·
2024
·Vol. 11
·期 6
·065006
·
IF 1.8
Senbuer Bao,Qizhi Chen,Wenjiang Shi,Peng Wang,Yanwei Wang,Shuwei Zhang,Lixin Wang,Deyuan Zou,Shuai Dong,Fanxing Meng,Jiawu Zhao,Shujun Xiang,Peng Wang
The physical mixing of inorganic fillers and a polymer matrix is a common method for constructing superhydrophobic coatings. Nevertheless, the interface bonding strength between the polymer and nanofiller was weak. The construction of interacting covalent bonds is a potential solution. In this study, carbon nanotubes were modified by aminopropyltriethoxysilane (APTES) and fluorosilane, and the reaction between the amino groups in APTES and -NCO(curing agent N3390) improved the bonding strength. Thus, the coatings maintained superhydrophobicity even after 260 abrasion cycles, 200 tape-peeling cycles, 18-day heat treatment, and acid/alkali attack. Furthermore, the corrosion current density could be reduced by three orders of magnitude compared with that of bare steel.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
ACS Catalysis
·
2019
·
IF 12.221
Mengrui Zhang,Vikram Singh,Xuefu Hu,Xinyi Ma,Jingkun Lu,Chao Zhang,Jingping Wang,Jingyang Niu
Design and synthesis of high-performance heterogeneous catalysts are of immense interest in chemical industries. Herein, ultrafine H2O coordinated WOx nanoparticles (H2O–WOx, average diameter 2.24 nm) embedded into porous carbon matrix have been obtained via space-confinement pyrolysis with postmodification oxidation approach. The synthesized H2O–WOx nanoparticles exhibit high activities toward olefin epoxidation reaction using H2O2 as oxidant. In epoxidation of cis-cyclooctene, the turnover frequency of the catalyst can achieve as high as 949 h–1, an activity comparable to the highest of all reported early transition-metal based catalysts. UV–vis spectra and controlled catalytic experiments have been performed to ascertain the possible active site in the catalyst: compared with traditional WO3 and peroxide coordinated W-(η2-O2) species, the water coordinated H2O–WOx can transform to hydroperoxide HOO–WOx in the presence of H2O2, and the HOO–WOx species can be further activated by proton acid to enhance its catalytic activities.
研究领域:
化学工程
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催化科学
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材料科学
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产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Qian Wang,Tingting Luo,Xinyu Zhao,Hongjian Xu,Yao Yao,Shujie Yang,Ganggang Chang,Xiaoyu Yang
Tandem catalytic processes present a cost-effective and energy-efficient route for the generation of fine chemicals. In this work, a hierarchical multifunctional MOF (mesoAg+@Al-bpydc) was successfully synthesized using a simple impregnation method, with AgBF4 serving as both the functional sites and etching agents. The incorporated Ag+ ions and N-based ligands are accountable for the selective epoxidation and cycloaddition reaction, respectively. Moreover, the hierarchical pore structures within the mesoAg+@Al-bpydc are anticipated to optimize the mass transfer rate and enhance accessibility of active sites. These advantages synergistically contribute to superior catalytic performance of mesoAg+@Al-bpydc for the one-pot oxidative carboxylation of olefins (conversion ∼99.68%, selectivity ∼50.83%), where the yield of the target product over mesoAg+@Al-bpydc is at least 37% higher than that of microporous counterparts. Moreover, based on the kinetic results and the comparison between single-step reaction and tandem reaction, it was found that the intermediate styrene oxide (SO) is unstable and is easily converted to benzaldehyde (BA) with the extension of reaction time in the individual epoxidation reaction (78.22% selectivity of BA), while generated SO can immediately couple with CO2 to produce SC in the tandem reaction (6.81% selectivity of BA). Consequently, more SC is accessible by rapidly consuming SO and impeding the overoxidation reaction, which supports the preponderance of the direct oxidative carboxylation of styrene and the synergistic effect of varied active sites in the tandem reaction. Besides, the composite mesoAg+@Al-bpydc allows easy separation and recycling at least five times with a negligible loss of activity.
研究领域:
化学工程
·
材料科学
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产品关联
DOI
高影响因子
Journal of CO2 Utilization
·
2024
·
IF 7.2
Cheng Zhang,Ning Zhou,Shiting Wang,Xiaoxia Yang,Tingyan Peng,Zhifeng Dai,Feiyong Xiang,Yubing Xiong
The efficient conversion of atmospheric CO 2 into high value-added chemicals remains a persistent challenge. In this study, a novel strategy for the fabrication of triazine- and amino-functionalized poly(ionic liquid)s (PILs) was reported. By virtue of the rich nitrogen species, the newly-developed PILs possessed great potential in CO 2 conversion to produce high-value chemicals. The systematic investigation illustrated that rich-nitrogen PILs could promote the cycloaddition reaction of CO 2 and epoxides through the intramolecular synergy of multiple active sites. Excellent conversion and selectivity were achieved under the mild conditions without any co-catalysts and solvents. In addition, PIL heterogeneous catalysts could be easily recovered and reused at least several times without obvious loss in activity. The density functional theory calculation demonstrated that the superior catalytic activity of rich nitrogen PILs was attributed to the synergistic effect of hydrogen bond donor and triazine ring in the catalytic process. Our finding thus presents a versatile platform for fabricating multi-functional heterogeneous catalysts for efficient CO 2 conversion.
研究领域:
化学
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催化材料
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环境科学
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产品关联
DOI
高影响因子
CHEMISTRY-A EUROPEAN JOURNAL
·
2017
·Vol. 23
·期 30
·7287-7296
·
IF 5.317
Wenbao Ma,Chen Chen,Kang Kong,Qifeng Dong,Kun Li,Mingming Yuan,Difan Li,Zhenshan Hou
Graphical IL at ease : Novel ionic liquids (ILs) consisting of quaternary phosphonium cations and a monomeric peroxotantalate anion have been prepared and their structures were determined accordingly. The ILs exhibited highly catalytic performance for the epoxidation of allylic alcohols under solvent-free and ice bath conditions. The parent anions of the ILs underwent structural changes after reaction with H 2 O 2 and a hydrogen-bond interaction between the peroxotantalate anion and hydroxyl group of allylic alcohols is proposed. The efficient and environmentally benign epoxidation of allylic alcohols has been attained by using new kinds of monomeric peroxotantalate anion-functionalized ionic liquids (ILs=[P 4,4,4, n ] 3 [Ta(O) 3 (η-O 2 )], P 4,4,4, n =quaternary phosphonium cation, n =4, 8, and 14), which have been developed and their structures determined accordingly. This work revealed the parent anions of the ILs underwent structural transformation in the presence of H 2 O 2 . The formed active species exhibited excellent catalytic activity, with a turnover frequency for [P 4,4,4,4 ] 3 [Ta(O) 3 (η-O 2 )] of up to 285 h −1 , and satisfactory recyclability in the epoxidation of various allylic alcohols under very mild conditions by using only one equivalent of hydrogen peroxide as an oxidant. NMR studies showed the reaction was facilitated through a hydrogen-bonding mechanism, in which the peroxo group (O–O) of the peroxotantalate anion served as the hydrogen-bond acceptor and hydroxyl group in the allylic alcohols served as the hydrogen-bond donor. This work demonstrates that simple monomeric peroxotantalates can catalyze epoxidation of allylic alcohols efficiently.
研究领域:
化学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）