Sustainable Energy & Fuels
·
2020
·Vol. 4
·期 11
·5795-5801
·
IF 5.503
Xiao Liu,Xue Min,Hui Liu,Yuanqiao Cao,Yadong Liu,Miaomiao Han,Zhong-Ming Sun,Shengxiang Ji
A heterogeneous cobalt-phosphonate network catalyst, [Co2(2,2′-bipy)(H4L)(H2O)]H2O (Co318), was synthesized by a hydrothermal reaction. The combination of Brønsted acid (–PO3H2) and Lewis acid (Co2+) sites makes Co318 an efficient catalyst for the conversion of saccharides to HMF. Under optimized conditions, glucose was quantitatively consumed and the yield of HMF was as high as 92%. Co318 was recycled four times without the loss of catalytic activity. When microcrystalline cellulose and regenerated cellulose were used, the yields of HMF were 33% and 50%, respectively, at 10 wt% catalyst loading. The yield of HMF increased to 59% when the loading of Co318 was increased to 40 wt%. GC-MS analysis confirmed that the reaction mixture contained both glucose and fructose intermediates, proving that the conversion of cellulose to HMF involved three steps: hydrolysis of cellulose to glucose, isomerization of glucose to fructose, and dehydration of fructose to HMF.
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PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION
·
2020
·Vol. 37
·期 5
·2000021
·
IF 3.099
Ali Maruf,Yi Wang,Li Luo,Yuan Zhong,Deti Nurhidayah,Boyan Liu,Dan Tang,Muhammad Abdul Rouf,Haijun Zhang,Yuxia Yin,Wei Wu,Guixue Wang
The development of smart nanoagents that can respond to a specific stimulus has gained remarkable interest for treating various kinds of diseases, including atherosclerosis. On the other hand, a cell camouflaging strategy has been considered as a pivotal factor to improve the delivery stealthiness, biocompatibility, and biodegradability of nanocarriers, resolving the shortcomings of PEGylation. In this study, reactive oxygen species (ROS)-responsive 5-aminolevulinic acid (ALA) prodrug nanostructures (ROSELLA) encapsulating rapamycin (RAP) are blended with nanoerythrocyte membranes to construct red blood cell membrane (RBCM)/RAP@ROSELLA. These nanoagents are designed to be able to escape the biological barriers, accumulate in atherosclerosis lesions, and enhance the release of drugs in the intracellular milieu due to the magnification of hydrogen peroxide (H 2 O 2 ). In vitro study proves its superior ability to inhibit the proliferation of macrophages and vascular smooth muscle cells. In vivo developmental toxicity further confirms that no significant systematic toxicity is induced by RBCM/RAP@ROSELLA, implying its favorable biocompatibility, which has potential for precise nanomedicine to combat atherosclerosis.
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APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
·
2020
·Vol. 104
·期 6
·2481-2488
·
IF 3.53
Xu Da,Fang Mengjun,Wang Haijiao,Huang Lei,Xu Qinyang,Xu Zhinan
5-Hydroxytryptophan (5-HTP) is the precursor of the neurotransmitter serotonin and has been used for the treatment of various diseases such as depression, insomnia, chronic headaches, and binge eating associated obesity. The production of 5-HTP had been achieved in our previous report, by the development of a recombinant strain containing two plasmids for biosynthesis of L-tryptophan (L-trp) and subsequent hydroxylation. In this study, the L-trp biosynthetic pathway was further integrated into the E. coli genome, and the promoter strength of 3-deoxy-7-phosphoheptulonate synthase, which catalyzes the first step of L-trp biosynthesis, was engineered to increase the production of L-trp. Hence, the 5-HTP production could be manipulated by the regulation of copy number of L-trp hydroxylation plasmid. Finally, the 5-HTP production was increased to 1.61 g/L in the shaking flasks, which was 24% improvement comparing to the original producing strain, while the content of residual L-trp was successfully reduced from 1.66 to 0.2 g/L, which is beneficial for the downstream separation and purification. Our work shall promote feasible progresses for the industrial production of 5-HTP.
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高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2020
·Vol. 138
·期 1
·49611
·
IF 2.52
Zongqi Zhang,Yuanfeng Wu,Lijing Gao,Guomin Xiao
This work aims at investigating the special application of ZSM-5/polydimethylsiloxane (PDMS) membrane being used for pervaporation separation of levulinic acid aqueous solutions. The effects of temperature, downstream pressure, feed concentration, and raw material ratio on the separation performance are investigated by self-made flat-sheet films. When the flow rate of feed pump remained at 0.4 ml/min (10 wt% levulinic acid), a levulinic acid permeation flux of 334.13 g/(m 2 h) and a separation factor of 2.382 at 75°C are observed over the composite membrane doped with 10 wt% ZSM-5. In addition, the acid resistance is enhanced after the PDMS membranes are doped with ZSM-5. Besides, the functionalized process also makes the membranes increase in its hydrophobicity. The results demonstrate that the ZSM-5/PDMS-based membranes show profound prospects for separating levulinic acid aqueous solution.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2020
·
IF 4.939
Zhaowei Li,Xiaosong Yang,Yingxiang Han,Long Rong
The conversion of biomass to produce high-valued chemical aromatic intermediates such as benzene (B), toluene (T), ethylbenzene (E), xylene (X), naphthalene (N) has attached booming interests. Herein, in order to obtain BTEXN aromatics on the hydrocracking of Jatropha oil, several LaNiMo/ZSM-5 catalysts (La loading from 0.5 to 15 wt%) by alkali treatment and metal impregnation methods were synthesized and investigated. Fundamentally, we found the alkali treatment engendered more mesoporosity to ZSM-5 and resulted in higher catalytic activity . It bears emphasis that further metal impregnated catalyst NiMo/ZSM-5 could improve the aromatics yield due to the increase of metal active sites and acidity sites. Besides, we noted that La loading had positive effects on coke reduction, catalytic stability and catalyst lifetime. To sum up, results confirmed the favorable 1 wt% La–NiMo/ZSM-5 had maximum 75 wt% BTEXN yield, longer catalyst lifetime for 100 h and decreased carbon deposits by 1.11%.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2021
·
IF 5.455
Yanliang Zhai,Yunshan Shang,Luoming Zhang,Xiaoling Meng,Yanjun Gong,Lirong Zheng,Jing Zhang,Ping Liu
Hydrothermally modified nanosheet ZSM-5 zeolite by directly using MnO x nanoparticles was carried out and this substantially offered a high performance catalyst for methanol to propylene (MTP) reaction. The properties of as synthesized ZSM-5 nanosheets with different MnO x amounts (NS-x) were compared with ZSM-5 nanosheets modified by impregnation method (IM-0.5) and physically mixed method (PM-0.5), respectively. The initial state of MnO x nanoparticles was close to Mn 2 O 3 with 20 nm in size. XRD , H 2 -TPR and XAFS results confirmed under high temperature hydrothermal condition, the Mn 2 O 3 nanoparticles disaggregated into Mn 2 O 3 clusters and entered the framework defects of nanosheet zeolite with high dispersion. Infrared spectra of hydroxyl groups (OH-IR) showed that the Mn 2 O 3 clusters were bonded with silanol defects both on the surface and inside zeolite, which substantially increased the stability of Mn 2 O 3 clusters and healed the framework defects. In contrast, the Mn species in the impregnated sample was close to the co-existence of Mn 2+ ions and MnO 2 nanoparticles with 2–3 nm, no interaction between Mn species and Si–OH group was determined. Notably, the typical sample (NS-0.5) with MnO x cluster modification performed much higher propylene selectivity and catalytic stability (~52%, 240 h, WHSV = 3 h −1 ), while the conventional IM-0.5 and PM-0.5 showed poor propylene selectivity (48%, 46%) and catalytic stability (166 h, 133 h) in MTP reaction. The excellent result should be attributed to the subtle control of external strong acid and the less structural defects, due to specific existence of bonded Mn 2 O 3 clusters.
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JOURNAL OF THE BRAZILIAN CHEMICAL SOCIETY
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2021
·Vol. 32
·期 8
·1598-1606
·
IF 1.838
Zhang Yangyang,Shao Chuan,Qin Dongling,Yang Gang
Solid acid-catalyzed dehydration of fructose to produce 5-hydroxymethylfurfural (5-HMF) has been a hotspot in biomass conversion research in recent years. In this study, a novel SAPO-34-based catalyst was prepared by consecutive steps of titanium doping, sulfuric acid impregnation, and sulfonic acid functionalization. Characterization of the catalyst with X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), BrunauerEmmett-Teller (BET), inductively coupled plasma optical emission spectrometer (ICP-OES), and acid-base titration revealed different pore structures and more acid content compared to SAPO-34. The catalyst was applied to the preparation of 5-HMF by dehydration of fructose, and the maximum yield (74.0%) of 5-HMF was obtained by reacting in dimethyl sulfoxide (DMSO) at 170 °C for 50 min. In addition, the applicability of the catalytic system to other substrates and the stability of the catalyst after five cycles were investigated, which are valuable for further probing on the concerned aspects.
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Catalysts
·
2021
·Vol. 11
·期 8
·915
·
IF 4.146
Yongjie Xin,Sichan Li,Haiyong Wang,Lungang Chen,Shuang Li,Qiying Liu
The selective hydrogenolysis of 5-hydroxymethylfurfural (HMF) platform molecule to 2,5-dimethylfuran (DMF) has attracted increasing attention due to its broad range of applications. However, HMF, with multiple functional groups, produces various byproducts, hindering its use on an industrial scale. Herein, a bimetallic Pt-FeOx/AC catalyst with low Pt and FeOx loadings for selective HMF hydrogenolysis to DMF was prepared by incipient wetness impregnation. The structures and properties of different catalysts were characterized by XRD, XPS, TEM, ICP-OES and Py-FTIR techniques. The addition of FeOx enhanced Pt dispersion and the Lewis acidic site density of the catalysts, and was found to be able to inhibit C=C hydrogenation, thereby im-proving DMF yield. Moreover, the presence of Pt promoted the reduction of iron oxide, creating a strong interaction between Pt and FeOx. This synergistic effect originated from the activation of the C–O bond over FeOx species followed by hydrogenolysis over the adjacent Pt, and played a critical role in hydrogenolysis of HMF to DMF, achieving a yield of 91% under optimal reaction conditions. However, the leaching of Fe species caused a metal–acid imbalance, which led to an increase in ring hydrogenation products.Keywords:5-hydroxymethylfurfural;2,5-dimethylfuran;hydrogenolysis;Pt-FeOx/AC;synergistic effect
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Crystals
·
2021
·Vol. 11
·期 10
·1247
·
IF 2.589
Changsheng Zhang,Kai Fan,Ge Ma,Chi Lei,Wei Xu,Jie Jiang,Bing Sun,Hongxing Zhang,Yunfeng Zhu,Song Wen
Hierarchical zeolites attract people’s attention due to their enhanced mass transfer properties in catalytic reactions. The research over obtaining these zeolites in green and efficient methods is of great significance for the current post-treatments and templating strategies tend to be costly for hierarchical zeolite synthesis. In this research, nanosized mesoporous ZSM-5 (SN-ZSM-5) zeolites have been synthesized without the addition of mesoscale templates under highly concentrated conditions. The physicochemical characteristics were systematically investigated by XRD, SEM, N2 sorption, TEM, and NMR. The SEM images showed ZSM-5 crystals with sizes between 50–110 nm were obtained. N2sorption and high-resolution TEM images gave direct evidence for the hierarchical structure of SN-ZSM-5. The forming mechanism for the hierarchical structure was proposed that the etching effect of the highly alkaline environment for the starting gels played a critical role in the formation of hierarchical structure. Catalytic tests in methanol-to-olefins (MTO) showed the SN-ZSM-5 performed a longer catalyst lifetime and higher propylene selectivity than the conventional ZSM-5 zeolites (C-ZSM-5) obtained from a traditional hydrothermal method. The features of hierarchical structure in the SN-ZSM-5 crystals and the sustainability for synthesis method could show a promising choice for wide applications of these SN-ZSM-5 zeolites in the future.Keywords:ZSM-5 zeolite;efficient synthesis;hierarchical;nano crystals
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Biomedical Materials
·
2021
·Vol. 16
·期 6
·065014
·
IF 3.715
Caini Yuan,Xinyun Long,Jinghua Li,Qing Cai
As a biocompatible and biodegradable polymer, poly(lactide-co-glycolide) (PLGA) has been widely used as a carrier to achieve controlled drug delivery in various forms. Focusing on skin tumor treatment, herein 5-fluorouracil (5-FU) was embedded into the core of coaxially electrospun PLGA fibers to get a drug-loaded core–shell fibrous membrane. In the coaxial electrospinning, poly(vinylpyrrolidone) was applied in the inner flow to facilitate the formation of the core–shell structured fibers. The morphology and micro-structure of the fibers were characterized by scanning electron microscope and transmission electron microscope. The influences of the molecular weights and chemical compositions of PLGA copolymers on the release behaviors were studied. The cytotoxicity of the fibers was characterized by cell proliferation and living-dead cell staining experiments. The results showed that faster release rates would be obtained if the copolymers were of lower molecular weights and higher fraction of glycidyl unit. All the prepared 5-FU loaded fibrous membranes were non-cytotoxic, suggesting their potential applications in skin tumor treatment.
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PubMed
高影响因子
CATALYSIS LETTERS
·
2019
·Vol. 150
·期 5
·1445-1453
·
IF 2.372
Ye Yuling,Yao Mengqin,Chen Honglin,Zhang Xiaoming
Abstract The silanol defects in ZSM-5 zeolite have been recognized as an important factor in catalytic activity. Here, ZSM-5 zeolites with different amounts of silanol defect sites were synthesized from synthetic gels containing fluoride medium and were applied as catalysts for trioxane synthesis. The results of XRD, SEM, NH 3 -TPD, Py-IR, OH-IR, 27 Al MAS NMR, 1 H MAS NMR, and TG indicated that all ZSM-5 zeolites showed similar crystal size, relative crystallinity, porosity, and the number of Brønsted acid sites. However, the silanol defects reduced obviously and the number of Lewis acid sites reduced correspondingly when a little NH 4 F was added in the synthesis gels and both of them decreased slightly with increase of F/Si ratio. Compared with ZSM-5 zeolite prepared in hydroxide medium, ZSM-5 zeolite prepared in fluoride medium displayed higher selectivity to trioxane and increased gradually with increase of F/Si ratio. Moreover, the lifetime of ZSM-5 zeolite prepared in fluoride medium was longer than that of prepared in hydroxide medium. Thus, ZSM-5 zeolite prepared in fluoride medium which contained the few silanol defects and low Lewis acid sites is an efficient catalyst for trioxane synthesis. Graphic Abstract
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高影响因子
PROCESS BIOCHEMISTRY
·
2019
·
IF 2.883
Bin Zou,Pengyun Wang,Zhenjiang Liu,Jiaojiao Xia,baihan Chen,Zhiyuan Tan
2,5-Furandicarboxylic acid (FDCA) has the potential to replace terephthalic acid (TPA) as a building block in the preparation of bio-based and degradable polyester materials. However, the lack of efficient and stable catalysts limits the commercial viability of FDCA production. In this work, metalloporphyrins were immobilized on mesoporous SiO 2 and used as a novel oxidase to convert 5-hydroxymethylfurfural (HMF) to FDCA. As the catalytic active center of P450 monooxygenases and horseradish peroxidase, supported palladium, manganese, ferri, and cobalt porphyrins via ionic-liquid-functionalized SiO 2 (PdPOP-SiO 2 , MgPOP-SiO 2 , FePOP-SiO 2 and CoPOP-SiO 2 ) were able to simulate oxidase alone under mild conditions. 100% HMF (0.02 M) conversion and 94.94% FDCA yield were achieved using PdPOP-SiO 2 as a biomimetic oxidase after a 12 h reaction at 373 K in water at atmospheric pressure. This type of mimetic oxidase is stable, inexpensive, and readily available, and the method developed in this work can potentially be used to oxidize HMF to FDCA in an industrial setting.
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