Reaction Chemistry & Engineering
·
2020
·Vol. 5
·期 3
·539-546
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IF 3.441
Guangcai Zhang,Lu Zhang,Xuesong Wang,Aicheng Chen,Qinhui Zhang
This work presented microfluidic processing of zeolite films in a capillary microreactor and its potential application for biomass conversion. Uniform and continuous HZSM-5 zeolite films were fabricated under a continuous flow hydrothermal system in which the film thickness could be precisely tuned by flow rate and synthesis time. The catalytic performance of this acidic HZSM-5 film capillary microreactor was evaluated by the continuous flow acetalisation reaction of glycerol with acetone, affording ∼62.61% solketal yield under mild and solvent free conditions. No deactivation was observed even after 100 h, indicating the excellent stability of this HZSM-5 film capillary microreactor. This microfluidic processing strategy provided an extended applicability in the fabrication of zeolite film-based capillary microchannels with a high length-to-diameter ratio or other chip-based microchannel devices.
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ChemCatChem
·
2019
·Vol. 11
·期 11
·2649-2656
·
IF 4.495
Kuo Zhou,Haiyan Liu,Huimin Shu,Shuwen Xiao,Dechao Guo,Yingxin Liu,Zuojun Wei,Xiaonian Li
Graphical Raney to the rescue ! High value-added 2,5-bisaminomethylfuran was one-pot synthesized from 5-HMF over Raney Ni with a yield of 60.7 %. DFT calculations were conducted to support our speculation that Ni can harmonize NH 3 and H 2 on its surface most suitably for the reductive amination reactions. Reductive amination of furfuryl alcohol, furfural and 5-hydroxymethylfurfural (5-HMF) were carried out on various metal catalysts. Over Raney Ni catalyst, we obtained the highest furfurylamine yields of 81.8 % and 94.0 % from furfuryl alcohol in absence and presence of H 2 , respectively. While furfural was used as the substrate, 100 % yield of furfurylamine could be achieved over Raney Ni under rather moderate conditions. Although 5-HMF was completely converted over all catalysts used, the highest yield of 2,5-bisaminomethylfuran (60.7 %) was obtained over Raney Ni at 160 °C in 12 h. The DFT calculations on the adsorption behavior of NH 3 and H 2 on different metal surfaces showed that the difference of the adsorption energy between NH 3 and H 2 on Ni is lower than those of other metals, indicating that less metal active sites on Ni surface is occupied by NH 3 , which leaves more active sites for dehydrogenation/hydrogenation reactions and in the end promotes the reductive amination reactions.
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Catalysis Science & Technology
·
2019
·Vol. 9
·期 10
·2673-2681
·
IF 5.726
Bing Hu,Yazhi Yin,Zixin Zhong,Dengdeng Wu,Guoliang Liu,Xinlin Hong
Maximizing the Cu–ZnO interface is regarded as the best strategy to promote methanol synthesis activity over CuZn catalysts. Reducing the ZnO particle size can enhance the Cu–ZnO interaction, but its synthesis with a sub-5 nm size still remains a challenge. Moreover, the fabrication of an active powder catalyst with an inverse ZnO/Cu configuration is still very rare. In this work, we report a facile synthesis of inverse ZnO/Cu catalysts by direct calcination of Cu@ZIF-8 (zeolitic imidazolate framework-8). The particle size of ZnO and Cu can be tuned by changing the Cu loading as well as the calcination temperature. Importantly, inverse ZnO/Cu catalysts with sub-5 nm ZnO were obtained under gentle calcination at 623 K. In the CO2 hydrogenation reaction, the highest methanol synthesis activity reached 933 g kgcat−1 h−1 at 533 K and 4.5 MPa, with a high turnover frequency (TOF) of 0.013 s−1, over an optimized C2Z-623 catalyst, which exceeds the commercial CuZnAl catalyst (HiFuel R120, Johnson Matthey) and has ranked the top reported value over advanced CuZn catalysts under comparable conditions. Such excellent activity is attributed to the inverse structure of Cu particles covered by sub-5 nm ZnO, which promotes the intimate Cu–ZnO interface with enhanced SMSI. Moreover, we find that the methanol turnover frequency (TOF) monotonically increases with decreasing the particle size of ZnO as well as Cu. It is proposed that reducing the ZnO size favors the spillover of reducible ZnOx species onto the Cu surface while lowering the Cu size is responsible for the enhanced amount of exposed Cu steps for accommodating Zn species, both of which could facilitate the formation of Zn covered Cu steps as active sites for methanol synthesis.
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FOOD RESEARCH INTERNATIONAL
·
2019
·
IF 3.579
Wei Xu,Nan Zhang,Zhentao Zhang,Pu Jing
Anthocyanins exist likely as complexes with flavones/metal ions in some plants. However, few studies indicate the complexation effects on bioactivities, i.e. antioxidant activities. The aim of this study was to evaluate effects of complexes of cyanidin-3-diglucoside-5-glucoside (CY3D5G) with rutin/Mg(II) on intrinsic antioxidant enzymes and mRNA expressions. All complexes exhibited cellular antioxidant activity in RAW264.7 cells, whereas half maximal effective concentration (EC 50 ) values of CY3D5G complexes were significantly lower than its alone. Combination indexes of CY3D5G-rutin, CY3D5G-Mg(II), and CY3D5G-rutin-Mg(II) complexes were < 1 ( p < .05), indicating of synergistic effects. Additionally, CY3D5G-Mg(II) rather than others significantly enhanced total antioxidant capacity, superoxide dismutase activity, and glutathione peroxidase activity while reducing malonic dialdehyde contents in H 2 O 2 -induced RAW264.7 cell model ( p < 0.05), which were further confirmed with the up-regulated mRNA expression of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), and the down-regulated p21 ( p < 0.05). Our results demonstrated that CY3D5G and its complexes might enhance cellular antioxidant activities via the Nrf2/HO-1 signaling pathway. Additionally, a synergistic antioxidant effect of CY3D5G in the present of rutin/ Mg(II) as regular food components was evident, suggesting anthocyanin might interact with dietary components such as Mg(II) or rutin in food matrix or biological systems and exhibit a stronger antioxidant activity than it alone. The Mg (II) that exhibited no antioxidant activities alone shows potential as a co-adjuvant for the anthocyanin antioxidant activity.
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CHEMOSPHERE
·
2019
·
IF 5.108
Rongji Cui,Suxia Ma,Jie Wang,Shujun Sun
The catalytic gas-phase H 2 O 2 oxidation of NO was achieved over Fe-based catalysts supported on montmorillonite K10, γ-alumina and ZSM-5. ESR tests illustrate that the three catalysts can catalyze decomposition of H 2 O 2 yielding highly reactive hydroxyl radicals , of which Fe/K10 has the fastest rate, followed by Fe/γ-alumina. Fe 3+ in Fe/K10 and Fe/γ-alumina show lower density of electron cloud due to a strong interaction between Fe 3+ and the support, which benefits the electron transfer from the H 2 O 2 to Fe 3+ , thus favoring the production of hydroxyl radicals. Fe species exist on the surface of Fe/K10 mainly in the form of Fe 2 O 3 , whereas Fe species of Fe/γ-alumina and Fe/ZSM-5 exist mainly in the form of Fe 3 O 4 , and it is found that Fe 2 O 3 is more active than Fe 3 O 4 in catalytic gas-phase H 2 O 2 oxidation of NO. Interestingly, Fe/ZSM-5 has the lowest efficiency in generating hydroxyl radicals, its NO removal efficiency is 90%, which is much higher than 47.5% for Fe/γ-alumina and 62.3% for Fe/K10. In-situ IR results suggested that Fe/ZSM-5 are dual functional in oxidation of NO, that is, whether both Fe ion sites and Brønsted acid sites collectively provide the catalytic functionality. In the meantime, a possible reaction mechanism on catalytic gas-phase H 2 O 2 oxidation of NO over Brønsted acid sites is proposed.
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ENZYME AND MICROBIAL TECHNOLOGY
·
2018
·
IF 2.932
Juan Han,Yunfeng Cai,Yun Wang,Lei Gu,Chunmei Li,Yanli Mao,Wenli Zhang,Liang Ni
In this work, a novel Ni 2+ &AABOB bifunctional core–shell magnetic composite nanoparticles (MNPs), Fe 3 O 4 @p(AABOB-co-AIM-Ni 2+ ), were synthesized for the immobilization of horseradish peroxidase (HRP). Two kinds of interaction are simultaneously incorporated to improve the stability and reusability of immobilized HRP: one is the coordination between Ni 2+ and amide group in HRP, and the other is the interaction of the wulff-type boronic acid group with cis-diol-containing HRP which belongs to a type of glycoproteins. Accordingly, the proposed approach achieved high enrichment capacity (174.75 mg/g, protein/beads), and the activity of immobilized HRP still achieved 80% after reuse for 5 cycles. The degradation efficiency of phenol in the presence of immobilized HRP reached 93% within 10 min, which was significantly higher than that of free HRP only about 50% within 20 min. In addition, the immobilized HRP can be easily separated from the reaction solution by an external magnetic field.
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Reaction Kinetics Mechanisms and Catalysis
·
2018
·Vol. 125
·期 2
·1055-1070
·
IF 1.515
Zhao Xinhong,Duan Weiting,Zhang Xiaoxiao,Ji Dong,Zhao Yu,Li Guixian
A modified solvent-free method has been developed to synthesize FeAPO-5 zeolite catalysts with hierarchical porous structure as well as high crystallinity and iron content. The effects of mechanochemical and low-temperature pretreatment, as well as the addition of hydrogen peroxide and seed crystals on the synthesis of FeAPO-5 were studied in detail. The composition and structural features of relatively pure resultant products were deeply analyzed by XRD, SEM, ICP-AES, CHN analysis, TG–DTA, UV–Vis diffuse reflectance spectroscopy and N 2 physisorption. Most importantly, low-temperature pretreatment towards H 2 O 2 -containing precursor mixtures can to a great degree improve the crystallinity of FeAPO-5 molecular sieve. Significantly, compared to the conventional micron-sized microporous FeAPO-5 zeolite, the hierarchical FeAPO-5 catalysts created by this modified solvent-free method show superior performance in phenol hydroxylation, in which the one with a high content of framework iron species exhibits the best catalytic performance, giving phenol conversion of about 40% and dihydroxybenzene selectivity of up to 80% at 50 °C within 3 h reaction time.
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Frontiers in Chemistry
·
2018
·
IF 4.155
Zeng Mengyan,Chen Kun,Tan Junyan,Zhang Jie,Wei Yongge
Oxidizing aldehydes to generate carboxylic acids is a crucial reaction in nature and in chemical industry. The aldehyde oxidation, an easily achieved process in liver cells, is inert toward autoxidation in industrial production and difficultly achieved under enzymatic condition (in water, at pH 7, at room temperature). Herein, we prepared a supramolecular catalyst which are nanospheres assembled in aqueous media by chromium centered Anderson polyoxometalates Na3[CrMo6O18(OH)3] (namely, CrMo6) and cationic pillar[5]arenes (namely, P5A) with 10 positive charges which can be used as the phase transfer catalysts (PTCs). This supramolecular catalyst was exploited on aldehydes oxidation under enzymatic condition with relatively good conversion. Through DLS monitoring, the diameters of nanospheres were variable while changing the charge ratios of the ionic complexes (P5A-CrMo6), and it is probably because of the closer charge ratios causing the more compact assemblies. Also, the nano-morphologies were monitored by TEM and SEM, and the nanostructures were characterized by zeta potential, the X-ray energy-dispersive spectroscopy (EDS), elemental analysis.
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Canadian Journal of Chemistry
·
2018
·Vol. 96
·期 12
·
IF 1.084
Guanhong Liu,Peipei Ren,Fan Yang,Xuekai Dou,Jun Wang,Youtao Song
Two novel isomeric colorimetric probes are established for simultaneous determination of copper ions using 2-hydroxy-5-methoxybenzaldehyde fluorescein hydrazone (5-HMBA-FH) and 2-hydroxy-3-methoxybenzaldehyde fluorescein hydrazone (3-HMBA-FH). They are synthesized by reacting fluorescein hydrazide with 2-hydroxy-5-methoxybenzaldehyde and 2-hydroxy-3-methoxybenzaldehyde, respectively, and then characterized by 1H-NMR, 13C-NMR, and infrared spectrum. The addition of copper ions to the solutions of two novel colorimetric probes can generate the obviously peaks at 498 nm in UV–vis absorption spectra along with a rapid colour change from colourless to dark yellow. The detection limits of the method for Cu2+ ion were 3.442 × 10−6 mol/L and 3.682 × 10−6 mol/L separately for 5-HMBA-FH and 3-HMBA-FH, respectively. The additions of other metal ions hardly affect the determination of copper ions. The proposed method was successfully applied to the analysis of Cu2+ ions in various samples. This method possesses high sensitivity, high simplicity, and minimized interference and will provide a great advantage in detecting copper ions in the environment, food, and medical applications.
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Journal of Energy Chemistry
·
2018
·
IF 3.886
Lei Hu,Ning Li,Xiaoli Dai,Yuqi Guo,Yetao Jiang,Aiyong He,Jiaxing Xu
The development of high-efficiency and low-cost catalysts is very crucial for the Meerwein-Ponndorf-Verley (MPV) reduction of biomass-derived 5-hydroxymethylfurfural (HMF) into 2,5-dihydroxymethylfuran (DHMF). In this work, an amorphous and mesoporous zirconium phosphonate catalyst (Zr-DTMP), which is a zirconium-containing organic-inorganic nanohybrid , was successfully designed and synthesized by the simple assembly of zirconium tetrachloride (ZrCl 4 ) and diethylene triaminepenta(methylene phosphonic acid) (DTMP). Satisfactorily, when Zr-DTMP was employed for the MPV reduction of HMF in the presence of 2-butanol ( sec BuOH), DHMF yield could be achieved as 96.5% in 3 h under a relatively mild reaction temperature of 140 °C. Systematic investigations indicated that this high catalytic activity should be mainly due to the cooperative role of enhancive Lewis acid site (Zr 4+ ) and Lewis base site (O 2− ) in activating the carbonyl group of HMF and dissociating the hydroxyl group of sec BuOH, respectively. Additionally, Zr-DTMP showed excellent catalytic stability, when it was successively used 5 recycles, its surface characteristics and textural properties still remained almost unchanged, and so, the catalytic activity was not obviously affected. More interestingly, Zr-DTMP could also be applied for the selective reduction of other biomass-derived carbonyl compounds , such as 5-methylfurfural (MF), furfural (FF), levulinic acid (LA), ethyl levulinate (EL) and cyclohexanone (CHN), into the corresponding products with high yields, which is beneficial to the effective synthesis of various valuable bio-based chemicals.
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FUEL PROCESSING TECHNOLOGY
·
2018
·
IF 3.956
Feng Huang,Wenzhi Li,Qingchuan Liu,Tingwei Zhang,Shengxin An,Dawei Li,Xifeng Zhu
A carbon solid acid was made by grafting benzenesulfonic acid groups on the tobacco stem-derived porous carbon, which was prepared from waste tobacco stem by simple carbonization . The catalyst was characterized by scanning electron microscope (SEM), N 2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), pyridine FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS). The catalyst exhibited excellent catalytic activity for 5-hydroxymethylfurfural (HMF) production from fructose and glucose in γ-valerolactone/water solvent, and high yields of HMF reached 93.7 and 43.8%, respectively. In addition, the high yields of total furans derived from fructose and glucose reached 96.8 and 54.1%, respectively. The benzenesulfonic acid group grafted onto the surface of inner pores of carbon allowed reusing the catalyst for at least five runs without obvious activity reduction. The good performance of the tobacco stem-derived carbon solid acid was determined by the unique surface active sites, such as high density of Brønsted acid, Lewis acid sites, oxygen-containing weak acidic sites and protonated nitrogen-containing functional groups. This study offered a promising approach for efficient carbohydrate conversion.
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BIORESOURCE TECHNOLOGY
·
2015
·
IF 4.494
Bo Zhang,Zhaoping Zhong,Paul Chen,Roger Ruan
Chemical vapor deposition with tetra-ethyl-orthosilicate as the modifier was applied to deposit the external acid sites of HZSM-5, and the modified HZSM-5 samples were used for the microwave-assisted catalytic fast pyrolysis (MACFP) of biomass for bio-oil production. The experimental results showed that the external acid sites of HZSM-5 decreased significantly when SiO 2 deposited amount increased from 0% to 5.9%. For product distribution, the coke yield decreased, the oil fraction yield decreased at first and then increased, and the yields of water and gas first increased and then decreased over the range of SiO 2 deposited amount studied. For chemical compositions in oil fraction, the relative contents of aliphatic hydrocarbons, aromatic hydrocarbons and oxygen-containing aromatic compounds first increased to maximum values and then decreased, while the relative content of oxygen-containing aliphatic compounds first decreased and then increased with increasing SiO 2 deposited amount.
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