CATALYSIS COMMUNICATIONS
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2018
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IF 3.463
Qinqin Wang,Mingyuan Zhu,Haiyang Zhang,Caixia Xu,Bin Dai,Jinli Zhang
Zr-modified ZSM-5 zeolite was successfully prepared, and Zn/Zr-ZSM-5 was employed as a catalyst for the acetylene hydration reaction. High catalytic activity, above 96% C 2 H 2 conversion, was achieved at 260 °C with a feed reactant ratio of H 2 O/C 2 H 4 = 4 and a GHSV of 90 h −1 . To understand the influence of zirconium addition in the zeolite, Fourier-transform infrared spectroscopy, X-ray diffraction, surface texture analysis (BET method), transmission electron microscopy, temperature programmed desorption of NH 3 , temperature programmed reduction by hydrogen and X-ray photoelectron spectroscopy techniques were used. The incorporation of zirconium in the zeolite enhanced Zn metal dispersion and metal–support interactions. Moreover, an enhanced concentration of weak acid sites and active catalytic sites were found to be responsible for the high catalytic activity of Zn/Zr-ZSM-5 for the acetylene hydration.
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BIORESOURCE TECHNOLOGY
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2018
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IF 5.807
Leilei Dai,Yunpu Wang,Yuhuan Liu,Roger Ruan,Dengle Duan,Yunfeng Zhao,Zhenting Yu,Lin Jiang
Catalytic fast pyrolysis (CFP) of torrefied corn cob using Ni-modified hierarchical ZSM-5 catalyst was conducted in this study. The prepared catalysts were characterized by N 2 adsorption and desorption (N 2 -BET), X-ray diffraction (XRD), and temperature-programmed desorption of NH 3 (NH 3 -TPD). NaOH solution treatment resulted in the lower peak intensities of hierarchical ZSM-5 catalyst in the XRD patterns while Ni modification improved the catalyst framework. In addition, NaOH solution treatment created some mesopores or macropores, but the incorporation of Ni reduced BET surface area and volume of micropores. Though the addition of Ni lowered the acidity of catalyst, Ni-modified hierarchical ZSM-5 catalyst led to higher yields and of aromatic hydrocarbons. What is more, hierarchical ZSM-5 catalysts significantly improved the selectivities of mono-aromatics. Kinetic analysis shows that CFP of torrefied corn cob was second-order reaction and the addition of Ni can obtain a lower activation energy compared with hierarchical ZSM-5 catalyst.
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APPLIED CATALYSIS A-GENERAL
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2018
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IF 4.521
Zhi Cao,Ming Li,Yong Chen,Tao Shen,Chenglun Tang,Chenjie Zhu,Hanjie Ying
The widely available reagent ethylenediaminetetraacetic acid (EDTA) was used as a temperature-responsive catalyst to produce 5-hydroxymethylfurfural (HMF) from fructose. Using this catalyst, a remarkable HMF yield of 89 ± 3% was achieved in a water-MIBK biphasic system containing polyvinylpyrrolidone (PVP) and 2-butanol. The pH of the reaction system based on EDTA as a catalyst was shown to be temperature-responsive. Moreover, the EDTA catalyst could be recycled simply by cooling the reaction liquid to room temperature due to its temperature-dependent solubility in water. A slight decrease in the yield of HMF (from 89 ± 3 to 81 ± 2%) was observed after EDTA repeated use for five cycles, and a yield of 88 ± 2% was achieved again after purification of the recycled EDTA via recrystallization with NaOH/HCl. The FTIR spectrum of recycled EDTA was almost the same as that of fresh catalyst, and TG analysis showed the decomposition temperature of EDTA is about 260 °C. Furthermore, a leaching test revealed that only 4.3 ± 0.2% of the initial EDTA was lost after five-time reuse.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
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2019
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IF 2.931
Yanqing Wang,Qianqian Han,Hongmei Zhang
Among the side effects of 5-fluorouracil (5-FU), the performance of the gastrointestinal reactions is faster and more obvious than others. In this work, the effects of 5-FU on the activities and conformational structures of the important digestive enzymes including α-amylase, pepsin and trypsin were studied to analyze the mechanism of the gastrointestinal adverse effects causing by 5-FU binding. The results showed that the enzymatic activity of pepsin was obviously reduced by the presence of 5-FU that bound directly to the enzyme activity cavity site. The molecular modeling and fluorescence quenching data indicated that the hydrophobic, polar and hydrogen bonding forces were involved in the ground state complex formation between proteases and 5-FU. In addition, 5-FU changed the tertiary structures of α-amylase, pepsin, and trypsin.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2018
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IF 11.698
Hua Zhou,Huanghui Xu,Yun Liu
Deriving more valuable products from renewable lignocellulosic biomass is attractive but still remains major challenges, the insufficient lignin valorization is considered as one of the main obstacles. Here, we report a novel catalyst comprised of cobalt nanoparticles (NPs) encapsulated in graphitic carbon tailored with manganese and nitrogen heteroatoms (Co-Mn/N@C), fabricated by pyrolyzing a mixture of Co/Mn-lignin complex and dicyandiamide. The as-synthesized Co-Mn/N@C catalyst exhibits excellent activity and recyclability for oxidizing biomass-derived 5-hydroxymethylfurfural (HMF) into 2,5-furandicarboxylic acid (FDCA) in aqueous system using O 2 as oxidant. The structure-performance relations of the catalyst are investigated, suggesting that Mn/N-doped carbon can activate the reactivity of Co NPs for HMF oxidation by tuning the electronic structure of embedded metal NPs. Additionally, isotopic labelling experiments reveal the role of water and O 2 for FDCA production using Co-Mn/N@C as catalyst. This work not only demonstrates the integrated biorefinery strategy, but also provides a new approach for sustainable, low-cost heterogenous catalysts preparation.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2018
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IF 3.412
Qianzhu Zhao,Juanying Ou,Caihuan Huang,Ruixia Qiu,Yong Wang,Fu Liu,Jie Zheng,Shiyi Ou
The absorption of a 5-hydroxymethylfurfural (HMF)–cysteine adduct, 1-dicysteinethioacetal–5-hydroxymethylfurfural (DCH), and its effect on antioxidant activity and gut microbiota were investigated. Results indicated that DCH is more easily absorbed in rats than HMF. Serum DCH concentrations were 15–38-fold of HMF concentrations from 30 to 180 min after intragastrical administration at the level of 100 mg/kg of body weight, and 2.7–4.5% of absorbed DCH was converted to HMF. The malondialdehyde content in the plasma, heart, liver, and kidneys significantly increased after drug (100 mg/kg of bw) administration for 1 week, suggesting that HMF and DCH were oxidative-stress-inducing agents, instead of antioxidant agents, in rats. HMF and DCH also modulated gut microbiota. HMF promoted the growth of Lactobacillus, Tyzzerella, Enterobacter, and Streptococcus. DCH increased the ratio of Firmicutes/Bacteroidetes and promoted the growth of Akkermansia, Shigella, and Escherichia while inhibiting the growth of Lactobacillus.
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COLLOIDS AND SURFACES B-BIOINTERFACES
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2014
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IF 4.287
Chunhua Gu,Vanminh Le,Meidong Lang,Jianwen Liu
Biodegradable graft copolymer, chitosan- graft -poly( ɛ -caprolactone) (CS- g -PCL) was synthesized via ring opening polymerization and characterized by 1 H NMR and FTIR spectroscopy. Then graft copolymers were self-assembled into micelles as drug delivery system. To evaluate drug-polymer compatibility, the Flory–Huggins interaction parameter between 5-fluorouraci (5-Fu) and hydrophobic segment was calculated. The result was in agreement with experimental data from drug loading content and drug loading efficiency. Meanwhile, DLS and TEM were utilized to evaluate the trend of particle size and morphology in aqueous solution with different repeating units of ɛ -CL. The in vitro drug release data was fitted with three kinetic models, usually applied in the drug delivery system. Results indicated that the release of 5-Fu was controllable and the release half-time could reach as long as 54.46 h, much slower than that of free 5-Fu. Cytotoxicity evaluation and cellular apoptosis study suggested good biocompatibility of CS- g -PCL micelles. Moreover, 5-Fu loaded micelles could delay the release of drug and exert comparable cytotoxicity against A549 cells.
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Journal of the Taiwan Institute of Chemical Engineers
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2014
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IF 2.637
Chuan-Jun Yue,Miao-Miao Gan,Li-Ping Gu,Ya-Feng Zhuang
Cu/ZSM-5 prepared by in situ impregnated reduction was used for the catalytic dehydration of glycerol under solvent-free conditions. The catalyst was characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), ammonia temperature programmed desorption (NH 3 -TPD), and thermogravimetry-differential scanning calorimetry (TG-DSC) analyses. Results showed that the nano-copper in Cu/ZSM-5 was evenly distributed onto the surface of ZSM-5 pores. Under the optimum conditions of the catalytic dehydration of glycerol, conversion was 92.1 wt.%. The selectivities of acrolein and acetol were 80.4 wt.% and 11.5 wt.%, respectively. Moreover, the low temperature favored for acetol selectivity. The synergic catalysis of Cu and ZSM-5 through the enol intermediate was responsible for the selectivity in the catalytic dehydration of glycerol.
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RSC Advances
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2013
·Vol. 4
·期 8
·4194-4202
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IF 2.562
Jinzhu Chen,Guoying Zhao,Limin Chen
Direct conversion of fructose into 5-hydroxymethylfurfural (HMF) and alkyl levulinate is achieved by making use of ionic liquid-based polyoxometalate salts (IL-POMs) as solid acid catalysts. Among these solid acids, phosphotungstic acid-derived IL-POM shows the highest catalytic performance in both the HMF and ethyl levulinate (EL) formation. A study for optimizing the reaction conditions such as the reaction time and the temperature has been performed. High HMF and EL yields of up to 99% and 82%, respectively, are obtained from fructose under the investigated conditions. Moreover, the generality of the catalyst is further demonstrated by processing representative di- and polysaccharides such as sucrose and inulin with good yields to HMF (76% from inulin and 48% from sucrose) and EL (67% from inulin and 45% from sucrose), again under mild conditions, thereby eliminating the separate hydrolysis step before the dehydration reaction. The catalyst recycling experiment indicates that the adsorption and accumulation of oligomeric products on the catalyst surface results in a partial deactivation of catalyst. The mechanism research reveals that a major pathway for EL formation involves a fructose-to-HMF transformation followed by HMF etherification and rehydration of HMF-ether to give EL. The research highlights an efficient, environment-friendly and recyclable solid acid for biomass valorization.
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CATALYSIS TODAY
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2013
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IF 2.98
Tong Zhang,Xiongfu Zhang,Xinjuan Yan,Lu Lin,Haiou Liu,Jieshan Qiu,King Lun Yeung
A well-designed Pd/ZSM-5@ZIF-8 core–shell structure has been prepared by application of a combination of seed-induction synthesis strategy and self-assembly synthesis techniques. First, uniform ZSM-5 particles with micron size and high crystallinity were prepared from organic-template-free gel systems containing 200 nm ZSM-5 seeds and exchanged with Pd(NO 3 ) 2 aqueous solution. Then incompatibility between the Pd/ZSM-5 core material and ZIF-8 shell precursor was circumvented by surface modification using a layer by layer self-assembly of polyelectrolyte, followed by a subsequent two-step temperature synthesis process inducing the formation of continuous and well-intergrown ZIF-8 shell. Thickness of ZIF-8 shell can be simply tuned by monitoring the assembly cycles. Furthermore, hydrogenations of 1-hexene and cyclohexene were chosen as model reactions to evaluate the catalytic behavior of the Pd/ZSM-5@ZIF-8 core–shell architecture and tert-dodecylthiol was used as a poison to test its anti-poisoning ability. Results show that such core–shell architecture exhibits excellent poison resistance and selectivity control properties for the hydrogenation reactions and can be potentially used as a membrane reactor in the field of heterogeneous catalysis.
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CHINESE JOURNAL OF CATALYSIS
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2015
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IF 1.964
Chuan Yuan,Huayan Liu,Zekai Zhang,Hanfeng Lu,Qiulian Zhu,Yinfei Chen
Various ZSM-5 zeolites modified with alkali metals (Li, Na, K, Rb, and Cs) were prepared using ion exchange. The catalysts were used to enhance the catalytic dehydration of lactic acid (LA) to acrylic acid (AA). The effects of cationic species on the structures and surface acid-base distributions of the ZSM-5 zeolites were investigated. The important factors that affect the catalytic performance were also identified. The modified ZSM-5 catalysts were characterized using X-ray diffraction, temperature-programmed desorptions of NH 3 and CO 2 , pyridine adsorption spectroscopy, and N 2 adsorption to determine the crystal phase structures, surface acidities and basicities, nature of acid sites, specific surface areas, and pore volumes. The results show that the acid-base sites that are adjusted by alkali-metal species, particularly weak acid-base sites, are mainly responsible for the formation of AA. The KZSM-5 catalyst, in particular, significantly improved LA conversion and AA selectivity because of the synergistic effect of weak acid-base sites. The reaction was conducted at different reaction temperatures and liquid hourly space velocities (LHSVs) to understand the catalyst selectivity for AA and trends in byproduct formation. Approximately 98% LA conversion and 77% AA selectivity were achieved using the KZSM-5 catalyst under the optimum conditions (40 wt% LA aqueous solution, 365 °C, and LHSV 2 h −1 ).
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FUEL
·
2013
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IF 3.357
Anqiu Liu,Bing Liu,Yimei Wang,Rongshen Ren,Zehui Zhang
Synthesis of 5-ethoxymethylfurfural (EMF) from the etherification of 5-hydroxymethylfurfural (HMF) and the dehydrative etherification of fructose over K-10 clay supported dodecatungstophosphoric acid (abbreviated as K-10 clay-HPW). 30% wt.% K-10 clay-HPW was found to be the efficient and robust catalyst for the synthesis of EMF. The highest EMF yield of 91.5% was obtained from HMF after 10 h at 100 °C. Further more, the catalyst also showed high catalytic activity for the dehydrative etherification of fructose with EMF yield of 61.5%. The reaction work-up is very simple and the catalyst could be reused several times without the significant loss of its catalytic activity.
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