POLYMER DEGRADATION AND STABILITY
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2023
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IF 5.9
Hang Shen,Zhihao Wu,Ruiyang Dou,Limin Jiao,Geng Chen,Mingzhang Lin,Wei Huang,Qiang Liu,Hongbing Chen
The developing nuclear technology has increased the need for radiation-resistant and shielding materials. It is crucial to study the radiation resistance of polymers in order to prevent safety incidents brought on by the degradation of polymer performance in a nuclear environment. In this work, γ-aminopropyltriethoxy silane (KH550) was successfully grafted onto carbon-doped boron (BCN) to obtain modified BCN (BCN-KH550), then BCN-KH550 was added in silicone rubber and refined and vulcanized. The elongation at break of silicone rubber composite doped with 0.3 phr BCN-KH550 can retain (54 ± 2)% of the initial value. The addition of BCN and BCN-KH550 both increases the initial decomposition temperature of the irradiated SR. The radiation caused changes in crystallinity and glass transition temperature (T g ) were measured using differential scanning calorimetry. The difference T g of BCN-KH550/SR0.3 before and after irradiation is 0.9 °C higher than that of SR. It is supposed that BCN protects the side group of SR during irradiation through differential thermogravimetric analysis curve and gas phase infrared spectra of the irradiation-induced gas products. BCN and BCN-KH550 can lower the hydrocarbon, CO 2 and CO production by side chain breakdown in both air and nitrogen atmospheres. The presence of BCN and BCN-KH550 decrease the radiation crosslinking of SR. The outcomes demonstrate that BCN-KH550 can reduce the effects of γ-radiation crosslinking on SR by declining side chain decomposition.
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ACS Catalysis
·
2023
·
IF 12.9
Chao Zhang,Yingqiang Li,Yue Xie,Zhanjiang Yu,Xin Wan,Xinzhi Wang,Jiaan He,Junlang Li,Zhenguo Chen,Xiaoyong Li,Xiaohui Yi,Zhaoli Wang,Guang-Guo Ying,Dionysios D. Dionysiou,Mingzhi Huang
Selective hydrodehalogenation and hydrodearomatization of toxic chlorophenols into value-added chemicals represents a grand challenge for their efficient reutilization. For this purpose, single-atom catalysts (SACs) could be a strategy with relatively high catalytic selectivity and atom utilization but suffer from the catalytic limitation caused by low metal loading densities. Graphdiyne and γ-graphyne are considered promising substrates of SACs with excellent catalytic properties. Additionally, their quantum dots with nanometer size are expected to supply numerous surface anchoring sites and large atom spacing to confine metal cations to synthesize high-loading SACs. Here we report a synthesis approach for high-loading Ru SACs anchored on graphdiyne/γ-graphyne quantum dots (GDQD-Ru/GNQD-Ru), which exhibit remarkably higher turnover frequency (TOF) and selectivity (>99%) of hydrodehalogenation and hydrodearomatization of chlorophenols than graphdiyne/γ-graphyne nanosheet-based Ru SACs and nanoparticles. There is no significant selectivity decrease in chlorophenol transformation by GDQD-Ru/GNQD-Ru observed in 5 catalyst reuse cycles. GDQD-Ru/GNQD-Ru contribute to nearly exclusive hydrodehalogenation and hydrodearomatization without altering any other bonds in chlorophenols. Experimental results and theoretical calculations reveal that GDQD-Ru is more prone to lower energies of rate-limiting steps in H2-driven chlorophenol transformation than GNQD-Ru. The results confirm that graphdiyne/γ-graphyne quantum dots play crucial roles in facilitating the metal atom loading of SACs. Ru loadings are 27.6 and 16.0 wt % in GDQD-Ru/GNQD-Ru, approximately 7-fold and 4-fold higher than reported Ru SACs, respectively. This study provides mechanistic insights toward the roles of high-loading Ru SACs on sp- and sp2-hybridized carbonaceous substrates in selective hydrodehalogenation and hydrodearomatization.
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Journal of Environmental Chemical Engineering
·
2021
·
IF 5.909
Xi Cheng,Qingge Feng,Dachao Ma,Hongcheng Chen,Xu Zeng,Feifan Xing,Jiayang Teng
To eco-friendly catalyze glucose to levulinic acid, recyclable acid catalyst has been researched. The synthesis process of propyl sulfonic acid functionalized SBA-15 was improved and the hydrophobic treatment was performed. The structure and functional groups of materials were characterized by X-ray diffraction, transmission electron microscopy , N 2 adsorption–desorption isotherms, elemental analysis, Fourier transform infrared spectroscopy , X-ray photoelectron spectroscopy and simultaneous thermal analysis. The catalytic activity , recyclability and hydrothermal stability of CH 3 -SBA-15-SO 3 H material were researched. The highest yield of levulinic acid at 61.56% was obtained at 180 ℃ for 2.5 h in γ-GVL-water solvent system, and the yield of levulinic acid was only decreased by 2% after 4 times reuse. The high degree of silicon polycondension and hydrophobic surface of CH 3 -SBA-15-SO 3 H were the key to maintain the hydrothermal stability. The CH 3 -SBA-15-SO 3 H solid acid had great potential in development and utilization of biomass resources .
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CHEMICAL ENGINEERING JOURNAL
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2021
·
IF 13.273
Zhihui Yao,Yuting Li,Daisong Chen,Yiwen Zhang,Xinghong Bao,Juan Wang,Qin Zhong
Carbon-based materials have shown promising results in replacing commercial Pt/C as highly efficient oxygen reduction reaction (ORR) catalysts in renewable energy devices. Designing unique structures of carbon matrix and introducing more active sites are essential for their application as electrode materials. Herein, a feasible approach is reported to synthesize dispersive γ -Fe 2 O 3 clusters embedded in 1D porous carbon nanofibers (CNFs) ( γ -Fe 2 O 3 @CNFs-12) through electrospinning, impregnation and pyrolysis processes. The resulted γ -Fe 2 O 3 @CNFs-12 exhibits excellent ORR performance in alkaline electrolyte with a surprising half-wave potential ( E 1/2 ) of 0.905 V and merely 5 mV drop of the potential after 5000 cycles, outperforming that of commercial Pt/C. Meanwhile, it also shows considerable ORR performance in acidic and neutral media. The remarkable ORR catalytic activity and durability are primarily attributable to the well-designed 1D hierarchical porous structure and accessible γ -Fe 2 O 3 clusters that embedded in carbon nanofibers. γ -Fe 2 O 3 @CNFs-12 is also capable to act as an air cathode for Zn-air batteries with an open circuit voltage of 1.428 V. This work provides a new perspective to the novel design and synthesis of carbon-based ORR electrocatalysts.
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高影响因子
FUEL
·
2021
·
IF 6.609
Rulu Huang,Yao Liu,Junhua Zhang,Junnan Wei,Lincai Peng,Xing Tang
Both value-added utilization of agricultural waste to prepare catalytic materials and selective conversion of biomass-based carbonyl compounds are hot topics. Herein, sugarcane bagasse ( SB ), a main by-product of cane sugar manufacturing industry, was directly assembled with HfCl 4 and methanesulfonic acid (MSA) via a one-step hydrothermal method for scalable preparation of Hf-containing coordination complex (Hf@ SB -MSA). Characterization results revealed that the coordination between Hf 4+ and phenolic hydroxyl, alcohol hydroxyl, carboxyl groups in SB resulting in the formation of Lewis acid (LA) and Lewis base (LB) sites, while sulfonic group in MSA providing Brønsted acid (BA) sites. The cooperative role of LA, BA and LB in Hf@ SB -MSA delivered prominent catalytic performance for catalytic transfer hydrogenation (CTH) of levulinic acid (LvA) to γ-valerolactone (GVL) with isopropanol as solvent and H-donor at mild reaction conditions (GVL yield was up to 99.1%). Heterogeneity and recycling experiments further revealed the good recyclability of Hf@ SB -MSA, which can be easily separated from the reaction mixture by filtration and repetitively used at least five reaction runs without an obvious loss of activity. More gratifyingly, Hf@ SB -MSA also displayed superior universality for the CTH of various carbonyl compounds to their corresponding alcohols with yields up to 90%.
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ACS Applied Bio Materials
·
2019
·
IF 0
Nier Wu,Huilei Yu,Muyang Sun,Zong Li,Fengyuan Zhao,Yingfang Ao,Haifeng Chen
Silk fibroin (SF) is a natural polymer with low immunogenicity and good biocompatibility. However, most silk-based hydrogels formed through chemical or physical cross-linking are brittle, the preparation of which also inevitably introduces cytotoxic cross-linking agents. Herein, a simple strategy is presented for synthesizing SF hydrogels with tunable mechanical properties by combining γ-ray radiation with ethanol treatment. Neither toxic initiators nor chemical agents are utilized during the whole preparation procedure. For “soft” hydrogels, the compressive moduli are less than 29 kPa (SF-S hydrogels), while for “tough” hydrogels, the compressive moduli are between 1.21 and 2.41 MPa (SF-D hydrogels). Specifically, γ-ray radiation makes SF form uniform and stable chemical cross-linking sites within and between molecular chains, resulting in “soft” and highly elastic SF hydrogels. The physical cross-linking via ethanol treatment leads to the self-assembly of fibroin chains, transforming those soft hydrogels to tough hydrogels. These double cross-linked SF hydrogels (SF-D hydrogels) exhibit excellent mechanical strength. Effects of various cross-linking conditions on the secondary structure, pore structure, mechanical properties, gelation degree, swelling, and in vitro degradation properties are explored. A series of cell experiments demonstrate that the SF hydrogels with different mechanical strength can stimulate the expression of specific genes of rat bone marrow mesenchymal stem cells (BMSCs) in various differentiation directions. These results also show the application prospects in tissue engineering by customizing hydrogels for the mechanical strength of different tissues.
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PubMed
Reaction Kinetics Mechanisms and Catalysis
·
2018
·Vol. 125
·期 1
·71-84
·
IF 1.515
Xie Yongdi,Wang Haijun,Liu Xiang,Xia Yongmei
Hydrogenation of levulinic acid and its esters to produce γ-valerolactone (GVL) is an important reaction in the process of biomass valorization. Herein, a series of novel and porous acid–base bifunctional Zirconium tripolyphosphate were successfully synthesized and utilized to catalyze the hydrogenation of ethyl levulinate (EL) to GVL. It was found that Zr-TPPA-3 with a large number of Lewis acid–base sites and a high specific area displayed the highest catalytic activity, a satisfied GVL yield of 93.1% with 99.5% EL conversion was obtained under the optimal reaction conditions. In addition, poisoning experiments revealed that the acid–base sites play a synergistic effect in the hydrogenation of EL to GVL, and finally proposed a plausible reaction mechanism.
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CHINESE JOURNAL OF CATALYSIS
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2018
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IF 3.525
Haojie Wang,Chun Chen,Haimin Zhang,Guozhong Wang,Huijun Zhao
Bimetallic nanostructures have attracted great interest as efficient catalyst to enhance activity, selectivity and stability in catalytical conversion. Herein, we report a facile one-pot carbothermal route to in-situ controllable synthesize heterogeneous bimetallic Ni 3 Fe NPs@C nanocatalyst. The X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and N 2 adsorption-description results reveal that the Ni 3 Fe alloy nanoparticles are evenly embedded in carbon matrix. The as-prepared Ni 3 Fe NPs@C catalyst shows excellent selective hydrogenation catalytic performance toward the conversion of levulinic acid (LA) to γ-valerolactone (GVL) via both direct hydrogenation (DH) and transfer hydrogenation (TH). In DH of LA, the bimetallic catalyst achieved a 93.8% LA conversion efficiency with a 95.5% GVL selectivity and 38.2 mmol g −1 h −1 GVL productivity (under 130 °C, 2MPa H 2 within 2 h), which are 6 and 40 times in comparison with monometallic Ni NPs@C and Fe NPs@C catalysts, respectively. In addition, the identical catalyst displayed a full conversion of LA with almost 100% GVL selectivity and 167.1 mmol g −1 h −1 GVL productivity at 180 °C within 0.5 h in TH of LA. Under optimal reaction conditions, the DH and TH catalytic performance of 500-Ni 3 Fe NPs@C(3:1) catalyst for converting LA to GVL is comparable to the state-of-the-art noble-based catalysts. The demonstrated capability of bimetallic catalyst design approach to introduce dual-catalytic functionality for DH and TH reactions could be adoptable for other catalysis processes.
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JOURNAL OF THE CHINESE CHEMICAL SOCIETY
·
2018
·Vol. 65
·期 11
·1370-1378
·
IF 0.862
Jianjia Wang,Ruiying Wang,Huimin Zi,Haijun Wang,Yongmei Xia,Xiang Liu
Catalytic transfer hydrogenation (CTH) of ethyl levulinate (EL) to γ-valerolactone (GVL) is an alluring reaction in the field of biomass catalytic conversion, but it normally depends on the consumption of H 2 . In this study, we report a porous Zr-containing inorganic pyrophosphate catalyst (ZrOPP), which was used as a catalyst for CTH of EL to GVL in the presence of isopropanol and characterized using FT-IR, py-FTIR, TGA, XRD, BET, XPS, ICP-AES, SEM, TEM, NH 3 -TPD, and CO 2 -TPD. We achieved a high yield of 94% GVL at 433 K for 11 hr. Furthermore, the ZrOPP has the trait of easy separation and could be reused more than five times without distinct decrease in activity and selectivity. In addition, this catalyst could also be applied to other catalytic hydrogenation reactions, such as those of cyclohexanone, acetophenone, 2-heptanone etc. Its outstanding performance was mainly ascribed to the acid sites from the Zr element and basic sites from phosphate groups interspersing on the surface of the catalyst.
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LWT-FOOD SCIENCE AND TECHNOLOGY
·
2018
·
IF 3.129
Hui Zhu,Faizan A. Sadiq,Yun Li,ShengYuan Yang,Fei Zhou
In this study, ion-exchange resin was applied as solid acid catalyst for the γ-aminobutyric acid (GABA) production using a strain of Enterococcus faecium (GZ2) by whole-cell bioconversion. It was observed that the accumulated GABA resulted in the inhibition of the bioconversion activity. To improve the productivity, a cation-exchange resin-based in situ product removal (ISPR) approach was developed. Three cation-exchange resins were tested to select a suitable adsorbent used in the bioconversion. The strong acidic cation-exchange resin IRP-69 exhibited the highest GABA production and remained helpful in reducing the free GABA concentration in the reaction solution. Compared to the bioconversion in sodium acetate buffer, the GABA production, with the addition of resin, was significantly improved by 2.12-fold. Furthermore, a fed-batch bioconversion strategy with the feeding of L-monosodium glutamate (L-MSG) was tested. The maximum production of GABA, 406.1 mM, was achieved after 12 h reaction with an initial substrate concentration of 200 mM, and a triple feeding of 100 mM L-MSG afterwards at 4 h, 6 h and 8 h. The result shows that the operation of bioconversion reaction in a feeding substrate batch mode is an effective approach to improve the efficiency and productivity of GABA.
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Journal of Materials Chemistry B
·
2013
·Vol. 1
·期 11
·1614-1621
·
IF 0
Yan Zhang,Jianjing Liu,Yutong Fu,Ke Tan,Zhaoyang Ye,Meidong Lang
A novel polyion complex (PIC) drug carrier was developed via electrostatic self-assembly in aqueous media based on our previous copolymer methoxy poly(ethylene glycol)-b-poly(γ-amino-ε-caprolactone) (mPEG-b-PACL) and anti-hepatotoxic drug ammonium glycyrrhizinate (AMG). The formation and the physicochemical properties of the polyion complex nanoparticles in aqueous solution were investigated by various methods. The results demonstrated that AMG was encapsulated successfully and the nanoparticles had a core–shell or tri-layer spherical structure based on the length of the PACL. The AMG/PACL PIC also displayed a high loading capacity and encapsulation efficiency of up to 41.8% and 91.7%, respectively. Furthermore, the nanoparticles enabled a continuous and sustained in vitro AMG release and the release half time was about 3 times that of the free AMG's. Results obtained by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, flow cytometry and fluorescence microscopy revealed that AMG loaded nanoparticles demonstrated greater prevention of liver cell apoptosis induced by lipopolysaccharide (LPS). These findings indicated that methoxy poly(ethylene glycol) (mPEG)-b-poly(γ-amino-ε-caprolactone) could be an efficient AMG carrier and could even be used as a delivery template for some other negatively charged water-soluble drugs or gene delivery systems.
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TheScientificWorldJOURNAL
·
2013
·
IF 1.73
Wei Lin Li,Shuan Bao Tian,Feng Zhu
A simple and efficient synthetic protocol has been developed for the synthesis of 3-substituted-2H-1,4-benzothiazines by using a novel sulfonic acid functionalized nano-γ-Al2O3 catalyst, devoid of corrosive acidic, and basic reagents. The developed method has the advantages of good to excellent yields, short reaction times, operational simplicity, and a recyclable catalyst. The catalyst can be prepared by a simple procedure from inexpensive and readily available nano-γ-Al2O3 and has been shown to be recoverable and reusable up to six cycles without any loss of activity.
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高影响因子
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