CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Yunjia Hu,Tengchao Guo,Kangsen Peng,Shujuan Tan,Cheng Xu,Jie Deng
In this study, Ce 1−x Cu x O 2−x (x = 0, 0.01, 0.03, 0.05, 0.07) samples were prepared by hydrothermal method . The structure, microstructure, and elemental composition of the powders were characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, whereas the electrical conductivity , ultraviolet–visible absorption spectroscopy , and infrared emissivity at 3–5 μm were measured as well. Moreover, the effects of Cu 2+ doping concentration on the microstructure, morphology, bandgap, conductivity, and infrared emissivity of Cu-doped CeO 2 powders were systematically studied. The effects of Cu 2+ doping on infrared reflection and absorption in a 3–5 μm band and their mechanisms were explained based on electromagnetic theory, lattice vibration absorption, and free carrier absorption . Our result indicated that the emissivity of 1% Cu-doped powder reached the lowest emissivity of 0.200 at 800 °C. When the doping concentration was above 1%, the curve of infrared emissivity versus temperature exhibited a “U” shape, with the minimum point shifting towards the low-temperature region with the increase of Cu doping amount. This phenomenon was attributed to the different enhancement amplitude of reflectivity and absorbance of CeO 2 powder by Cu 2+ at different temperatures.
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高影响因子
ChemistrySelect
·
2022
·Vol. 7
·期 43
·e202202460
·
IF 2.307
Guohao Xu,Jiale Zhu,Xuedong Zhu
Graphical Compared with the microporous system of MoO 3 /ZSM-5 synthesized by the the physically-blended method, the micro-mesoporous system of ZSM-5@MoO 3 with a core-shell reaction pathway of Mo-acid sites tandem could accelerate the rate of the mass-transfer, promoting aromatization reaction. A novel core-shell ZSM-5@MoO 3 catalyst was successfully synthesized by the hydrothermal coating strategy, and its physicochemical properties and catalytic properties in methane aromatization were investigated using a physically-blended ZSM-5/MoO 3 catalyst as a comparison. Multitechniques including XRD, SEM, TEM, EDS, N 2 adsorption, ICP, IR and IG were employed to investigate the characteristics of methane aromatization reaction and the deactivation of carbon deposits. At the reaction temperature of 700 °C and a space velocity of 2400 mL g −1 h −1 , methane conversion and aromatics selectivity of the core-shell ZSM-5@MoO 3 catalyst were 11.3 % and 88.1 %, respectively, which were higher than those of the physically-blended ZSM-5/MoO 3 catalyst by 3.1 % and 14.8 %, respectively. The special reaction pathway of core (ZSM-5, acid sites)-shell (MoO 3 , Mo sites) and the relatively close proximity between MoO 3 and ZSM-5 were mainly responsible for the excellent properties in the methane aromatization reaction. At the same time, the formation of the micro-mesoporous property accelerated the mass-transfer rate and inhibited the formation of carbonaceous deposition, greatly improving the stability of methane aromatization. Thanks to its core-shell structure, ZSM-5@MoO 3 catalyst showed the excellent properties in methane aromatization.
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JOURNAL OF POWER SOURCES
·
2020
·
IF 8.247
Ning An,Zhuhang Shao,Zhen Guo,Jiao Xin,Yuanyuan He,Liwen Lv,Kefeng Xie,Xiuyan Dong,Yang Zhang,Zhongai Hu
In this work, we select a novel multi-redox poly (1, 5-diaminoanthraquinone) (PDAAQ) as electroactive material and Cetyltrimethylammonium bromide (CTAB) modified graphene oxide (CGO) as conductive substrate. Benefit from the excellent dispersion of CGO in organic polymerization medium and the abundant functional groups on the surface of CGO, 1, 5-diaminoanthraquinone (DAAQ) monomers may covalently graft on the conducting substrates and realize the directional growth of PDAAQ via the in-situ chemical oxidative polymerization. In three-electrode system, the optimization of PDAAQ/CGO electrode exhibits a high specific capacitance of 760 F g −1 at 1 A g −1 and superior electrochemical stability of 90.4% after 10 000 cycles. Most importantly, the electrochemical kinetic behavior of PDAAQ/CGO electrode is studied in detail. The result indicates that the energy storage process of PDAAQ/CGO is a synergistic result of diffusion-controlled process and capacitive effects, and the latter one is dominant. According to the simulation calculation of kinetic model , the capacitive contribution ratio of PDAAQ/CGO can be as high as 80.6% at a scan rate of 50 mV s −1 . Finally, the as-fabricated asymmetric supercapacitor (ASC) can deliver an energy density up to 41.1 W h kg −1 at a power density of 1000 W kg −1 , indicating a great potential application in high performance supercapacitors .
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高影响因子
FUEL
·
2018
·
IF 4.908
Jun Zhang,Kaijun Dong,Weimin Luo,Haifeng Guan
Sulfonic acid modified organic hyper-cross-linked polymer (HCP) based carbocatalyst with variable –SO 3 H density and porosity, was synthesized for the one-pot conversion of biomass derived carbohydrates into potential fuel candidate 5-ethoxymethylfurfural (EMF). The structural characterizations revealed that the porous structure of HCP was well maintained after sulfonation process, thus rendering good structure and high Brϕnsted acid density for the one-pot dehydrative etherification reaction. The as-prepared HCP materials exhibited promising catalytic performance for ketoses conversion, which yielded 78.9% of EMF along with 15.4% 5-hydroxymethylfurfural (HMF) and 4.6% ethyl levulinate (EL) using fructose as starting material in ethanol-DMSO biphasic system. Meanwhile, considerable increase in EMF yield from glucose based carbohydrates was attained when adding slight amounts of Lewis acid AlCl 3 to reaction protocol. The HCP based catalyst was able to be reused several times without significant loss in catalytic activity. More importantly, the HCP materials were also highly active in other related acid-catalyzed reactions, including esterification, transesterification and dehydration.
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Advances in Materials Science and Engineering
·
2022
·Vol. 2022
·期 1
·7408284
·
IF 2.098
Zhenhao Wei,Yufan Ji,Yiping Huang,Jingjing Huang,Yunguo Huang,Changhai Yue,Junzhou Li,Mingwei Tang,Yunfang Liu,Hanfei Liu,Hao Zhu,Kai Zhu,Fan Yang,Xuedong Zhu
Zinc (Zn) and cerium (Ce) modified hierarchical ZSM-5 (HZ) catalysts were prepared by incipient wetness impregnation, and their catalytic performances in methanol to aromatics reaction were evaluated in a fixed-bed reactor operating at 400°C under 0.1 MPa and WHSV of 1.0 h −1 . The structure, acidity, and state of Zn species of the Zn/Ce modified HZ catalysts were investigated via several characterization techniques, including XRD, NH 3 -TPD, H 2 -TPR, nitrogen adsorption, and XPS. The results showed that the aromatization activity of 2 wt% Zn-modified HZ (2% Zn/HZ) could be significantly enhanced by loading 0.6 wt% Ce, which was mainly attributed to the increase in surface ZnOH + species. Moreover, it was found that Ce inhibited pore blockage caused by Zn. Consequently, compared to 2% Zn/HZ, 2% Zn-0.6% Ce/HZ exhibited higher aromatic selectivity and longer catalyst lifetime.
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JOURNAL OF NANOPARTICLE RESEARCH
·
2023
·Vol. 25
·期 8
·1-11
·
IF 2.5
Dong Qi Zheng,Huang Xin Yi,Huang Cheng
A composite luminescent material consisting of perovskite quantum dots (PQDs) and MOF-5 using an in-situ growth method. The preparation of MOF-5 as a growth template was achieved via hydrothermal synthesis, with the addition of CTAB/TMB as a stencil agent to facilitate the formation of pores with an appropriate size. Subsequently, CsPbBr 3 QDs were grown in situ on the MOF under mechanical grinding conditions. The prepared CsPbBr 3 @MOF-5 composite materials were characterized by various analytical techniques including BET, XRD, PL, TEM, SEM, and EDS. The results revealed that the average size of PQDs was only 4.9 nm, and the corresponding emission peak exhibited a blue shift of 11 nm. The photoluminescence intensity (PL) of CsPbBr 3 @MOF-5 was increased by 71% compared to the unmodified sample, and photoluminescence quantum yield (PLQY) of solid powder increased to 48%. This is due to the fact that MOF-5 reduces the surface defects of quantum dots. Additionally, the Significantly improved PQDs stability after compounding MOF, both at room temperature and under thermal stress. These findings highlight the potential of this synthetic strategy as a means of preparing ultra-small composite light-emitting materials, with promising applications in LED and optoelectronic devices.
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高影响因子
DYES AND PIGMENTS
·
2018
·
IF 3.767
Xiao-Lei Zhao,Jiao Geng,Bin Hu,Dan Xu,Wei Huang
New monomethine dyes have been prepared by a simple and highly efficient method in acetic anhydride, in which the common pyridine-2,6-dione moiety and thiophene derivatives occupy each side of the methine unit. Among them, the ternary monomethine-azo dyes were first obtained by the particularly useful post-modification synthetic strategy, in order to further adjust the π -conjugated system and electronic spectra of 2-amino-3-cyano-4-chloro-5-formylthiophene based heterocyclic hydrazone/azo dyes. UV−Vis spectral analyses reveal that the synthesized heterocyclic dyes exhibit a large color gamut because of the extension of the conjugation length of the chromophore , where the maximum absorption wavelength ( λ max ) is significantly red-shifted up to 181 nm from binary monomethine to ternary monomethine-azo dyes.
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高影响因子
ChemistrySelect
·
2024
·Vol. 9
·期 35
·e202402568
·
IF 1.9
Rui Zhu,Xinglong Li
Graphical A photocatalytic selective oxidation strategy for preparing DFF from HMF is developed, using Ag/Ag 3 PO 4 as the photocatalyst and O 2 as the oxidizing agent. In contrast to previous photocatalytic oxidation strategies for HMF transformation, this catalytic system could efficiently generate 1 O 2 without other ROS under visible light irradiation. DFF would be obtained with 88 % selectivity with the optimal reaction conditions. The synthesis of 2,5-diformylfuran (DFF) through photocatalytic oxidation of 5-hydroxymethylfurfural (HMF) is an attractive approach. In this manuscript, a photocatalytic selective oxidation strategy for HMF was developed, using Ag/Ag 3 PO 4 as the photocatalyst and O 2 as the oxidizing agent. The prepared catalyst was characterized systematically by SEM, XRD, XPS, UV-Vis, PL spectra, and so on. In contrast to previous photocatalytic oxidation strategies for HMF conversion, this catalytic system could efficiently generate 1 O 2 without other reactive oxygen species (ROS) under visible light irradiation. DFF would be obtained with about 90 % selectivity. Moreover, the exclusive formation of 1 O 2 was linked to the more positive conduction band potential (+0.90 eV) of Ag/Ag 3 PO 4 , confirmed by an array of characterization techniques. Additionally, the stability of the catalyst was assessed through cyclic testing and analyses including XRD, and XPS. Nonetheless, this catalytic system could potentially serve as a robust platform for various selective oxidation reactions in the future, due to its exclusive presence of 1 O 2 without the involvement of other ROS.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2022
·
IF 5.876
Hao Zhang,Guang-Ren Qian,Hong Liu
Alumina composites containing microporous ZSM-5 (Z-5) and mesoporous ZSM-5 (MZ-5), corresponding to x ZA and x MZA, were developed by incorporating Z-5 and MZ-5 into γ - Al 2 O 3 , respectively. The two series of NiMoS/ x MZA and NiMoS/ x ZA catalysts were prepared with these two composites as supports, respectively, and were used for the simultaneous hydrodesulfurization (HDS) of thiophene (T) and benzothiophene (BT). The results show that NiMoS/ x MZA series catalysts exhibit higher HDS activity than that of NiMoS/ x ZA and NiMoS/γ-Al 2 O 3 , and the HDS activity of NiMoS/ x MZA catalysts increases with the increase of MZ-5. The high HDS activity can be mainly attributed to the synergistic effects of the efficient diffusing pore channels, high dispersion of type II NiMoS phases, suitable acidity, and moderate Mo-support interaction. Moreover, the product distribution of HDS shows that the NiMoS/ x MZA catalysts possess the dominant direct desulfurization (DDS) selectivity and the selectivity increases with the increase of MZ-5 content due to more corner sites and suitable Brønsted (B) acid sites, whereas the NiMoS/ x ZA catalysts perform more excellent hydrogenation (HYD) selectivity, and the selectivity increases with the increase of Z-5 content because of the existence of more edge sites. Based on this, the possible reaction network for T and BT hydrodesulfurization over the catalysts are proposed.
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CHINESE JOURNAL OF CATALYSIS
·
2014
·
IF 1.552
Shurong Wang,Qinjie Cai,Xiangyu Wang,Li Zhang,Yurong Wang,Zhongyang Luo
Acids and ketones in biomass pyrolysis oil (bio-oil) can be readily cracked to produce hydrocarbons. They can also be enriched in the distilled fraction using molecular distillation techniques. To simulate the actual composition of the distilled fraction, the co-cracking performance of mixtures of hydroxypropanone, cyclopentanone, and acetic acid with ethanol in a fixed-bed reactor over an HZSM-5 catalyst was studied. The influences of reaction temperature and pressure on the reactant conversion, selectivity, and composition of the oil phase were investigated. At a low reaction temperature of 340 °C, the conversions of acetic acid and ethanol were as low as 67.9% and 74.4%, respectively, and the oil phase had a low hydrocarbon content of 59.8%, with large amounts of oxygenated byproducts. Cracking under atmospheric pressure also generated a low-quality oil phase with a very low selectivity of only 10.8%. Increasing the reaction temperature promoted reactant conversion and improved the deoxygenation efficiency, whereas increasing the reaction pressure significantly promoted hydrocarbon production. The optimum conditions for biogasoline production were 400 °C and 2 MPa. Under these conditions, the reactant conversion reached 100% and the oil phase selectivity was 31.5 wt%. This oil phase consisted entirely of hydrocarbons, 91.5 wt% of which were aromatic hydrocarbons , indicating that the HZSM-5 catalyst had high activity for deoxygenation and aromatization reactions during cracking. In addition, characterization of the spent catalysts and stability tests showed that the catalyst was deactivated after a long reaction time. However, the catalytic activity was recovered by catalyst regeneration.
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ACS Catalysis
·
2016
·
IF 9.307
Shanhui Zhu,Yanfeng Xue,Jing Guo,Youliang Cen,Jianguo Wang,Weibin Fan
The high-yield synthesis of the biofuel γ-valerolactone (GVL) is a challenging task, which currently stems from the depolymerization of cellulose to levulinic acid, followed by its hydrogenation. We have developed a novel integrated process for the production of GVL from hemicellulose without using liquid acids and external hydrogen. The hemicellulose feed underwent hydrolysis and consecutive dehydration to produce furfural over ZSM-5 catalyst. Subsequently, the formed furfural with 2-propanol performed tandem conversion to GVL over Au/ZrO2 catalyst combined with ZSM-5. This process gave a high yield of GVL under mild conditions: up to 61.5% based on hemicellulose. The outstanding performance was mainly ascribed to the strong interface interaction of Au with ZrO2 species, large amounts of medium-strength acid sites over ZSM-5, and efficient synergy between active metal and acid sites.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Pan Wang,Jinxin Liu,Yue Ma,Xiaohua Tian,Yuzhu Li,Xiangheng Niu,Jianquan Luo,Jianming Pan
Precise control of imprinting processes and reasonable selection of molecularly imprinted polymers (MIPs) carriers are essential for realizing highly selective and fast separation. In this work, Janus polymer nanosheets (J-PNs) with different wettabilities on two sides were synthesized by self-polymerizing dopamine based on octadecylamine (ODA) lamellae with a bilayer structure, followed by a sequential imprinting assembly of low pKa boronic acid and pyrimidine base monomers on the hydrophilic side of J-PNs to prepare Janus imprinting sorbents (J-MIPs) for highly specific separation of adenosine 5′-monophosphate (AMP). The sequential assembly strategy integrated two different functional monomers together to simultaneously interact with the surrounding template AMP molecule and to precisely control the imprinting site orientation, enabling the resulting J-MIPs with strong and specific binding toward AMP. Janus amphiphilic J-MIPs can be well fixed at the dodecane/water interface, which was benefit for their fast recycle and simple regeneration, and the uptake amount of the fifth adsorption/elution cycle was 86.08% of the first one. The equilibrium time and maximum adsorption capacity of tailor-made J-MIP were 4.0 h and 13.69 μmol g −1 at 298 K, respectively. Taking the advantage of cooperative multi-point interaction, binding sites with high affinity to AMP accounted for about 76.71% of the total sites, and the high imprinting factor (2.182) of the J-MIP against non-imprinted counterpart was observed. In addition, 61.30% of AMP in spiked human serum sample can be selectively extracted by J-MIPs, due to the highly specific receptor sites from sequential imprinting assembly.
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