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Berlin Brandenburg

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  • RSC Journals (Royal Society of Chemistry)  (40)
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  • 1
    In: Green Chemistry, 2013, Vol.15(1), pp.152-159
    Description: Design and preparation of efficient and greener catalytic systems for partial hydrogenation of benzene to cyclohexene is an interesting topic in green chemistry. In this work, Ru and RuZn catalysts supported on hydroxyapatite (HAP), which is nontoxic and abundant in nature, were prepared via the simple ion-exchange method. The catalysts were characterized by powder X-ray diffraction (XRD), transmission electron spectroscopy (TEM), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorptiondesorption methods. The influences of Ru/Zn molar ratio, reaction temperature, pressure, reaction time, and amount of modifier NaOH on the partial hydrogenation of benzene were studied in detail. It was demonstrated that metallic nanoparticles of less than 2 nm were dispersed uniformly on the surface of the HAP, and the bimetallic RuZn/HAP catalysts showed high activity and selectivity. The yield of cyclohexene could reach 33% over RuZn/HAP at the optimized conditions, and the catalyst could be reused at least four times without obvious loss of the activity and selectivity.
    Keywords: Zinc ; Green Development ; Temperature ; Catalysts ; X-Ray Diffraction ; Spectroscopy ; Ion Exchange ; Benzene ; Nitrogen ; Environmental Design & Urban Ecology ; Issues in Sustainable Development;
    ISSN: 1463-9262
    E-ISSN: 1463-9270
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  • 2
    In: RSC Advances, 2014, Vol.4(18), pp.9292-9299
    Description: The cage-like mesoporous material SBA-16 has been successfully functionalized with l -4-hydroxyproline and characterized by Fourier transform infrared (FT-IR) spectroscopy, Small-angle X-ray powder diffraction (XRD), N 2 sorption detection, transmission electron microscopy (TEM), elemental analysis and thermo gravimetric analysis (TGA). This chiral non-metallic catalyst avoided heavy metal pollution during the preparing and using process, and demonstrated high catalytic activity (up to 91%), diastereoselectivity (up to 97:3) and enantioselectivity (up to 83%) in the asymmetric aldol reaction between aldehyde acceptors and ketone donors with methanolH 2 O as solvent. Moreover, the synthesized catalyst could be easily separated from the reaction mixture by filtration and reused for up to five runs without any obvious loss of activity, indicating its excellent recyclability.
    Keywords: Sorption ; Filtration ; Ketones ; Fourier Transforms ; Gravimetric Analysis ; Heavy Metals ; Microscopy ; Solvents ; Catalysts ; Aldehydes ; Spectroscopy ; General Pollution;
    ISSN: 2046-2069
    E-ISSN: 2046-2069
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  • 3
    In: Green Chemistry, 2010, Vol.12(1), pp.65-69
    Description: 1-Aminoethyl-3-vinylimidazolium bromide ([VAIM]Br) grafted on the cross-linked polymer polydivinylbenzene (PDVB) was synthesized. The copolymers were used as a support to immobilize palladium nanoparticles. The catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG) analysis, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The catalytic performance of the copolymer-supported Pd nanoparticles for the Heck arylation of olefins with different aryl iodides was studied under solvent-free conditions. The results demonstrated that the catalyst was very active and stable under solvent-free conditions, and could be reused after simple separation. The reason for the high activity and stability of the catalyst is discussed.
    Keywords: Fourier Transforms ; Iodides ; Microscopy ; Catalysts ; Green Development ; Polymers ; Spectroscopy ; Palladium ; Issues in Sustainable Development;
    ISSN: 1463-9262
    E-ISSN: 1463-9270
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  • 4
    In: Catalysis Science & Technology, 2016, Vol.6(14), pp.5590-5598
    Description: Sulfonated cation exchange resins (s-CERs) have been widely studied as a replacement of liquid acids for the catalysis of esterification of free fatty acids (FFAs) to produce biodiesel with water as the only by-product. However, the water produced has strong affinity to sulfonate groups in s-CERs, which block the reactive sites for esterification and thus reduce the activity of a catalyst. To overcome this technical barrier, we have designed an s-CER/PVA composite by incorporating s-CER fines within a poly(vinyl alcohol) (PVA) matrix. PVA has a much stronger absorption preference for water than s-CERs and has very low selectivity for reactants (FFAs and methanol), which enables continuous removal of the produced water and liberation of reactive sulfonate sites in s-CERs for catalysis. With s-CER/PVA, FFA conversion was increased from 80.1% to 97.5% after an 8-hour reaction and the turnover frequency (TOF) was increased more than 3.3 times. The TOF of s-CER/PVA was also 2.6 times higher than that of sulfuric acid, suggesting that water-less, heterogeneous sulfonate sites are more reactive than water-blocked homogeneous ones. The reusability of s-CER/PVA was also enhanced due to the fact that the produced water that could cause deactivation of the s-CERs was largely removed by PVA.
    Keywords: Sulfonates ; Fatty-Acids ; Process-Water ; Cation-Exchange-Resin ; Vinyl-Alcohol ; Reactant ; Methanol ; Sulfuric-Acid ; Catalysis ; Deactivation ; Mixed-Material ; Reactive-Site ; Affinity ; By-Product ; Sulfonat ; Fettsäuren ; Betriebswasser ; Kationenaustauschharz ; Vinylalkohol ; Reaktant ; Methanol ; Schwefelsäure ; Katalyse ; Deaktivierung ; Komposit ; Reaktive Stelle ; Affinität ; Nebenprodukt ; Chemistry;
    ISSN: 2044-4753
    E-ISSN: 2044-4761
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  • 5
    In: RSC Advances, 2017, Vol.7(45), pp.28038-28047
    Description: The micro-mesoporous materials ZF- x (ZSM-5-FDU-12, x = SiO 2 /Al 2 O 3 ) with different molar ratios of SiO 2 /Al 2 O 3 were synthesized by an in situ nano-assembly method with the ZSM-5 precursor serving as the silica source. The physicochemical properties of the supports and the corresponding catalysts were analyzed in detail by various techniques including SEM, TEM, XRD, nitrogen physisorption, FTIR, UV-Vis, pyridine IR, Raman and XPS. The nitrogen physisorption measurement showed that the composite ZF-130 possessed excellent physical properties compared to other ZF- x materials. In addition, the XPS spectra displayed that catalysts NiMo/ZF- x showed a higher sulfurization than NiMo/FDU-12, and the NiMo/ZF-130 exhibited the highest contents of MoS 2 and NiMoS. In addition, DBT was employed as the probe molecule to evaluate the HDS (hydrodesulfurization) performance of the sulfide catalysts of NiMo/ZF- x under different weight hourly space velocities (WHSVs) 20120 h 1 , while NiMo/FDU-12 was used as the reference. Furthermore, the relationship between the structure of micro-mesoporous materials and the HDS activities of catalysts was systematically evaluated. The HDS efficiencies followed the order NiMo/ZF-130 〉 NiMo/ZF-110 〉 NiMo/ZF-150 〉 NiMo/ZF-90 〉 NiMo/ZF-70 〉 NiMo/FDU-12 under the operation conditions of 340 C, 4.0 MPa, and H 2 /oil of 200 20120 h 1 . Compared to other NiMo/ZF- x catalysts, NiMo/ZF-130 displayed the highest efficiency of DBT HDS, 96.3% at 20 h 1 , which could be attributed to the synergistic effects of its larger pore sizes (14.9 nm), greater specific surface area (352 m 2 g 1 ), moderate B and L acid sites, and the highest ratios of Mo 4+ /Mo (58%) and NiMoS/NiT (64%).
    ISSN: 2046-2069
    E-ISSN: 2046-2069
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  • 6
    In: RSC Advances, 2019, Vol.9(4), pp.1982-1989
    Description: Cisplatin is the most widely used anticancer drug, but its side effects limit the maximum systemic dose. To circumvent the side effects, a DNA tetrahedronaffibody nanoparticle was prepared by combination of a DNA chain with cisplatin via interstrand crosslinks or adducts. Each nanocarrier can bind 68 molecules of cisplatin. This cisplatin nanoparticle exhibited high selectivity and inhibition for breast cancer HER2 overexpressing cells BT474 and lower toxicity in MCF-7 cells with low HER2 expression. The nano-drug inhibited the growth of BT474 cells by 94.57% at 512 nM (containing 33.3 M cisplatin), which was higher than that of cisplatin (82.9%, 33.3 M).
    Keywords: Side Effects ; Chemotherapy ; Adducts ; Nanoparticles ; Cancer ; Deoxyribonucleic Acid–DNA ; Inhibition ; Nanoparticles ; Crosslinking ; Tetrahedrons ; Toxicity ; Breast Cancer ; Selectivity;
    ISSN: 2046-2069
    E-ISSN: 2046-2069
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  • 7
    In: Green Chemistry, 2012, Vol.14(6), pp.1743-1748
    Description: The effective conversion of carbon dioxide (CO 2 ) and glycerol is an interesting topic in green chemistry. In this work, we studied the simultaneous transformation of CO 2 and glycerol to value-added products using propylene oxide (PO) as coupling agent catalyzed by alkali metal halides. The effects of reaction temperature, CO 2 pressure, reaction time, amount of catalyst, and PO to glycerol molar ratio on the reaction were investigated. It was discovered that the coupled catalytic reaction could produce glycerol carbonate (GC), propylene glycol (PG) and propylene carbonate (PC) very effectively using KI, an abundant and cheap salt, as the catalyst. The main reasons are that glycerol and PG are not only the reactant and product, respectively, but also act as the effective co-catalysts to promote the key step of the coupled reaction, and the reaction is thermodynamically favorable. This effective and atom economic route to convert glycerol and CO 2 simultaneously has great potential application.
    Keywords: Salts ; Green Development ; Economics ; Temperature ; Catalysts ; Alkali Metals ; Carbon Dioxide ; Halides ; Issues in Sustainable Development ; Air Pollution;
    ISSN: 1463-9262
    E-ISSN: 1463-9270
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  • 8
    In: RSC Advances, 2013, Vol.3(43), pp.20085-20090
    Description: Development of an efficient catalytic system for the dehydration of carbohydrates to produce 5-hydroxymethylfurfural (HMF), which is a platform molecule for biomass transformation, is a very attractive topic. In this work, three DBU-based ionic liquids (ILs) were prepared and used as the solvent for the conversion of carbohydrates into HMF. It was found that all these new ILs were excellent solvents for the dehydration of glucose, cellulose, fructose, sucrose, inulin, and cellobiose to form HMF using CrCl 3 6H 2 O as the catalyst. The effects of temperature, reaction time, catalyst amount, and substrate/solvent weight ratio on the dehydration of glucose in CrCl 3 6H 2 O/Bu-DBUCl were studied systematically. It was shown that the yield of HMF could reach 64% from glucose. In addition, the CrCl 3 6H 2 O/Bu-DBUCl system could be easily separated from the product, and could be reused five times without considerably decreasing in activity and selectivity.
    ISSN: 2046-2069
    E-ISSN: 2046-2069
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  • 9
    In: Chemical Communications, 2017, Vol.53(63), pp.8850-8853
    Description: We explored the oxidation reactions of lignin model compounds directly induced by ionic liquids under metal-free conditions. In this work, it was found that ionic liquid 1-octyl-3-methylimidazolium acetate as a solvent could promote the aerobic oxidation of lignin model compound 2-phenoxyacetophenone ( 1 ) and the yields of phenol and benzoic acid from 1 could be as high as 96% and 86%, respectively. A possible reaction pathway was proposed based on a series of control experiments. An acetate anion from the ionic liquid attacked the hydrogen from the -carbon thereby inducing the cleavage of the CO bond of the aromatic ether. Furthermore, it was found that 2-(2-methoxyphenoxy)-1-phenylethanone ( 4 ) with a methoxyl group could also be transformed into aromatic products in this simple reaction system and the yields of phenol and benzoic acid from 4 could be as high as 98% and 85%, respectively. This work provides a simple way for efficient transformation of lignin model compounds.
    ISSN: 1359-7345
    E-ISSN: 1364-548X
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  • 10
    In: CrystEngComm, 2015, Vol.17(38), pp.7406-7413
    Description: A series of MnCO 3 and MnC 2 O 4 microstructures were fabricated via a self-templated method, in which carbon spheres obtained by a carbonization process in the same solution served as cores and templates. The shape of carbon@MnCO 3 /MnC 2 O 4 evolved from rhombi, to ellipsoids, to dumbbells, and to twin-sphere particles, depending on the setting time and temperature of the pre-mixing period. The carbon core was completely removed after calcination at 550 C, and a phase transformation to Mn 2 O 3 hollow microstructures was achieved, retaining their original shapes. The catalytic activities of the as-obtained Mn 2 O 3 hollow microstructures for CO oxidation were examined. The catalytic activities decreased in the order of Mn 2 O 3 ellipsoids dumbbells 〉 twin spheres 〉 rhombi.
    Keywords: Mikrostruktur ; Kohlenstoff ; Muldenaufbau ; Regelungssynthese ; Calcinieren ; Phasenumwandlung ; CO-Oxidation ; Katalytische Aktivität ; Engineering;
    ISSN: 1466-8033
    E-ISSN: 1466-8033
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