- Hydrogen and chemicals from alcohols through electrochemical reforming by Pd-CeO2/C electrocatalyst
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The development of low-cost and sustainable hydrogen production is of primary importance for a future transition to sustainable energy. In this work, the selective and simultaneous production of pure hydrogen and chemicals from renewable alcohols is achieved using an anion exchange membrane electrolysis cell (electrochemical reforming) employing a nanostructured Pd-CeO2/C anode. The catalyst exhibits high activity for alcohol electrooxidation (e.g. 474 mA cm?2 with EtOH at 60 °C) and the electrolysis cell produces high volumes of hydrogen (1.73 l min?1 m?2) at low electrical energy input (Ecost = 6 kWh kgH2?1 with formate as substrate). A complete analysis of the alcohol oxidation products from several alcohols (methanol, ethanol, 1,2-propandiol, ethylene glycol, glycerol and 1,4-butanediol) shows high selectivity in the formation of valuable chemicals such as acetate from ethanol (100%) and lactate from 1,2-propandiol (84%). Importantly for industrial application, in batch experiments the Pd-CeO2/C catalyst achieves conversion efficiencies above 80% for both formate and methanol, and 95% for ethanol.
- Bellini, Marco,Pagliaro, Maria V.,Marchionni, Andrea,Filippi, Jonathan,Miller, Hamish A.,Bevilacqua, Manuela,Lavacchi, Alessandro,Oberhauser, Werner,Mahmoudian, Jafar,Innocenti, Massimo,Fornasiero, Paolo,Vizza, Francesco
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- PROCESSES FOR PREPARING ALDARIC, ALDONIC, AND URONIC ACIDS
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Various processes for preparing aldaric acids, aldonic acids, uronic acids, and/or lactone(s) thereof are described. For example, processes for preparing a C2-C7 aldaric acid and/or lactone(s) thereof by the catalytic oxidation of a C2-C7 aldonic acid and/or lactone(s) thereof and/or a C2-C7 aldose are described.
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Paragraph 0110-0111
(2021/05/29)
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- Influence of Pd and Au on electrochemical valorization of glycerol over Ni-rich surfaces
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Herein we synthesized bi-metallic Pd@Ni and Au@Ni core-shell-like nanoparticles (NPs) for glycerol electrooxidation reaction (GEOR) in alkaline media. The morphological, structural and surface properties of the NPs were evaluated using a range of physicochemical techniques. The catalytic activity and stability were studied using the three-electrode electrochemical cell and 25 cm2- continuous electrolysis cell. Among different atomic ratios, Ni80Pd20 and Ni90Au10 nanoparticles showed the highest current densities which are ~4.5 and 4.2 times higher than spherical Ni, respectively. The addition of Pd and Au (a remarkable glycerate selectivity of ~73.1% and 65.7% for Ni80Pd20 and Ni90Au10 catalysts at 1.3 V and 50 °C, respectively. Notably, after 6 h of electrolysis Pd@Ni and Au@Ni tend to suppress the C-C bond cleavage, compared to Ni at any applied potentials and temperatures. The DFT calculations predicted that the addition of Pd or Au to Ni reduces the work function of M@Ni NPs, which strengthens the OH adsorption and enhances the removal of GEOR intermediates.
- Houache, Mohamed S.E.,Shubair, Asma,Sandoval, Mario G.,Safari, Reza,Botton, Gianluigi A.,Jasen, Paula V.,González, Estela A.,Baranova, Elena A.
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- The selective oxidation of glycerol over metal-free photocatalysts: insights into the solvent effect on catalytic efficiency and product distribution
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Selective oxidation of glycerol to high value-added derivatives is a promising biomass conversion pathway, but the related reaction mechanism, in particular the solvent effect, is rarely studied. In this work, O-doped g-C3N4was used as a metal-free catalyst to catalyze the selective oxidation of glycerol in different solvents. It was found that solvents can affect both catalytic efficiency and product distribution. A series of controlled experiments and theoretical calculation were applied to attest that the difference in interaction between glycerol and catalysts in different solvents is the main factor: competitive adsorption and hydrogen bond network from water inhibit the adsorption and activation of glycerol on the catalyst surface and reduce the conversion efficiency, while in acetonitrile, the stronger adsorption makes the oxidation reaction continue to yield esters. Two reaction routes in different solvents over O-doped g-C3N4are proposed for the first time, which is helpful for people to better understand the related reaction mechanism.
- Fan, Mingming,Haryonob, Agus,Jiang, Pingping,Leng, Yan,Yue, Chengguang,Zhang, Pingbo
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p. 3385 - 3392
(2021/06/06)
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- A proof of concept for cooperation from the quinone groups adjacent to N sites during the metal-free oxidation of glycerol by nitrogen-rich graphene oxide
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Glycerol is a key by-product in biodiesel production and can be utilized in the synthesis of value-added chemicals. The low cost and fairly abundant availability of glycerol can be advantageous in producing a variety of pharmaceuticals and cosmetic products. Among the various catalytic transformations, selective oxidation is a promising pathway for the valorization of glycerol. In this present report, we deliver a first proof of concept for the involvement of quinone groups adjacent to N sites on the GO surface, for the selective oxidation of glycerol to dihydroxyacetone (DHA). Graphene oxide is covalently functionalized with 2,4-dihydroxypyridine (DHP), which resembles the identified active sites in the carbon clusters. As anticipated, the DHP-functionalized graphene oxide catalyst (DHP@GO) improved the conversion of glycerol to DHA, the main product, along with minor amounts of glyceric acid (GA) and fumaric acid (FA).
- Barlocco, Ilaria,Dogra, Ashima,Gupta, Neeraj,Sharma, Vinit,Villa, Alberto
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supporting information
p. 19651 - 19654
(2021/11/12)
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- Assembly of platinum nanoparticles and single-atom bismuth for selective oxidation of glycerol
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Selective oxidation of the secondary hydroxyl group of glycerol to dihydroxyacetone (DHA) is an extremely challenging yet important reaction. The main difficulty is that the three hydroxyl groups in glycerol are prone to randomly oxidize, resulting in an unsatisfactory DHA selectivity. We show here that an assembly of platinum nanoparticles (NPs, ~2 nm) and N-stabilized single-atom bismuth (Bi), namely Pt/Bi@NC, shows a record-high DHA selectivity of ~95.0% towards glycerol oxidation under optimized reaction conditions. Characterization and theoretical calculations confirm that single-atom Bi in the vicinity of Pt NPs provides a preferred site to chelate with the primary -OH of glycerol, and its secondary -OH is prone to bind to a surface Pt atom of a Pt NP with a shorter Pt-H bond length. This as-formed unique adsorption configuration of glycerol on the Pt-Bi dual site significantly facilitates the oxidation of the secondary -OH of glycerol, thus contributing to a record-high selectivity to DHA. This journal is
- Huang, Ning,Jiang, Dong,Jiang, Pingping,Leng, Yan,Lu, Yubing,Tian, Jinshu,Yue, Chenguang,Zhang, Pingbo,Zhang, Zihao
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supporting information
p. 25576 - 25584
(2021/12/07)
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- Transfer hydrogenation of CO2into formaldehyde from aqueous glycerol heterogeneously catalyzed by Ru bound to LDH
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Aqueous glycerol was used in this study as a liquid-phase hydrogen source for the hydrogenation of CO2. It was found that hydrogen could be efficiently evolved from aqueous glycerol upon highly dispersed Ru on layered double hydroxide (LDH), inducing the transformation of CO2 into formaldehyde under base-free conditions at low temperature.
- Deng, Lidan,Liu, Xiaowei,Xu, Jie,Zhou, Zijian,Feng, Shixiang,Wang, Zheng,Xu, Minghou
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supporting information
p. 5167 - 5170
(2021/05/31)
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- Selective oxidation of glycerol over different shaped WO3 supported Pt NPs
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In this work, different shaped WO3 (rod-like, lamellar and cuboid) supported Pt catalysts were prepared in a facile routine and tested in the selective oxidation of glycerol in base-free aqueous solution. Characterizations indicated that rod-like WO3 supported Pt catalyst (Pt/R-WO3) possesses higher surface area because of the formation of vertical pore channels and highly exposed plane (100), the deposited Pt atoms combined strongly with the terminal [sbnd]W[dbnd]O in rod-like WO3. These properties promoted the adsorption, storage and surface diffusion of oxygen over Pt/R-WO3 which exhibited the excellent activity for the selective oxidation of glycerol. And the higher amount of acid sites on the surface of Pt/R-WO3 enhanced the selectivity of glyceric acid. The calculated turnover frequency of each Pt atom in Pt/R-WO3 reached 946 h–1 at 60 °C.
- Yang, Lihua,Jiang, Yuanyuan,Zhu, Zihui,Hou, Zhaoyin
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- Ambient base-free glycerol oxidation over bimetallic PdFe/SiO2 by in situ generated active oxygen species
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Low temperature oxidation of alcohols over heterogeneous catalysts is exceptionally challenging, particularly under neutral conditions. Herein, we report on an efficient, base-free method to oxidise glycerol over a 0.5%Pd-0.5%Fe/SiO2 catalyst at ambient temperature in the presence of gaseous H2 and O2. The exceptional catalytic performance was attributed to the in situ formation of highly reactive surface-bound oxygenated species, which promote the dehydrogenation on the alcohol. The PdFe bimetallic catalyst was determined to be significantly more active than corresponding monometallic analogues, highlighting the important role both metals have in this oxidative transformation. Fe leaching was confirmed to occur over the course of the reaction but sequestering experiments, involving the addition of bare carbon to the reactions, confirmed that the reaction was predominantly heterogeneous in nature. Investigations with electron paramagnetic resonance spectroscopy suggested that the reactivity in the early stages was mediated by surface-bound reactive oxygen species; no homogeneous radical species were observed in solution. This theory was further evidenced by a direct H2O2 synthesis study, which confirmed that the presence of Fe in the bimetallic catalyst neither improved the synthesis of H2O2 nor promoted its decomposition over the PdFe/SiO2 catalyst.
- Underhill, Ricci,Douthwaite, Mark,Lewis, Richard J.,Miedziak, Peter J.,Armstrong, Robert D.,Morgan, David J.,Freakley, Simon J.,Davies, Thomas,Folli, Andrea,Murphy, Damien M.,He, Qian,Akdim, Ouardia,Edwards, Jennifer K.,Hutchings, Graham J.
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p. 303 - 324
(2021/01/07)
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- Electro-oxidation of glycerol into formic acid by nickel-copper electrocatalysts
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Herein, non-precious metallic nickel-copper electrocatalysts were synthesized for electro-oxidation of glycerol in alkaline electrolytes. Activated carbon felt (ACF) is used as a supporting material because of its good conductivity, chemical inertness, and porous structure which is conducive to the transport of the reactants/electrons. The structural features of the catalysts were characterized by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The electrochemical activity of the catalysts was revealed by cyclic voltammetry, linear sweeping voltammetry, and chronoamperometry. The electrochemical results show that the Cu1Ni1@ACF catalyst possesses the highest current density of 1.31 mA cm-2 at 1.895 V. High-performance liquid chromatography results show that the as-prepared catalysts have high selectivities for formic acid (FA). Especially, the Cu1Ni1@ACF catalyst yields a selectivity of 97.4% for FA, which has so far been the largest value reported in the literature. Additionally, the effects of applied potentials and reaction time on product selectivity were studied.
- Shen, Yi,Zhang, Jiali
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- carba Nicotinamide Adenine Dinucleotide Phosphate: Robust Cofactor for Redox Biocatalysis
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Here we report a new robust nicotinamide dinucleotide phosphate cofactor analog (carba-NADP+) and its acceptance by many enzymes in the class of oxidoreductases. Replacing one ribose oxygen with a methylene group of the natural NADP+ was found to enhance stability dramatically. Decomposition experiments at moderate and high temperatures with the cofactors showed a drastic increase in half-life time at elevated temperatures since it significantly disfavors hydrolysis of the pyridinium-N?glycoside bond. Overall, more than 27 different oxidoreductases were successfully tested, and a thorough analytical characterization and comparison is given. The cofactor carba-NADP+ opens up the field of redox-biocatalysis under harsh conditions.
- D?ring, Manuel,Sieber, Volker,Simon, Robert C.,Tafertshofer, Georg,Zachos, Ioannis
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supporting information
p. 14701 - 14706
(2021/05/13)
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- Glycerol Oxidation Catalyzed by High-valency Ruthenium Species at Electrochemical Interfaces
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Herein we report high-valency ruthenium (Ru) species as a new class of electrocatalyst for glycerol oxidation. In this study, Ru-modified covalent triazine framework (Ru-CTF) and ruthenium oxide supported on carbon (RuO2/C) were used as model materials with high-valency Ru species. The results of this work show that the deep oxidation reactions of glycerol involving C-C bond cleavage can be effectively suppressed by increasing the glycerol concentration relative to the number of active Ru atoms for both catalysts.
- Harada, Takashi,Iwase, Kazuyuki,Kamiya, Kazuhide,Kato, Shintaro,Nakanishi, Shuji,Tabata, Hiro,Yamaguchi, Shingi
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supporting information
p. 513 - 516
(2020/05/18)
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- Selective oxidation of glycerol with oxygen in base-free solution over N-doped-carbon-supported Sb?PtSb2 hybrid
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Selective oxidation of glycerol with molecular oxygen in base-free aqueous solutions has become a hot topic, as the rapidly increasing production of biodiesel is creating a surplus of glycerol. In this work, an N-doped-carbon-supported core-shell structured Sb?PtSb2 hybrid catalyst was prepared via a facile synthesis route, in which a mixture of glucose, melamine, and SbCl3 (Sb-NC) was pyrolyzed, then impregnated with Pt by immersion in an aqueous solution of H2PtCl6, and further treated in hydrogen flow. Characterization of the catalyst products indicated that introducing SbCl3 can increase the surface area of the binary glucose + melamine pyrolyzed support (NC), and Sb?PtSb2 hybrids could be formed on the surface of an Sb-NC support during hydrogen treatment at 700 °C. It was found that the Sb?PtSb2/NC catalyst was more active for the selective oxidation of glycerol in a base-free aqueous solution than Sb-free NC-supported Pt (Pt/NC). Further characterization also indicated that the promising performance of Sb?PtSb2/NC might be attributed to its enhanced oxygen activation.
- Yang, Lihua,He, Tianqu,Lai, Chujun,Chen, Ping,Hou, Zhaoyin
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p. 494 - 502
(2019/12/26)
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- Glycerol Selective Oxidation to Lactic Acid over AuPt Nanoparticles; Enhancing Reaction Selectivity and Understanding by Support Modification
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A high surface area mesoporous TiO2 material (110 m2/g) was synthesised using a nanocasting methodology, utilizing SBA-15 as a hard template. This material was subsequently used as a support to prepare a series of 1 wt.% AuPt/TiO2 catalysts, synthesised by conventional impregnation and sol-immobilisation. Catalysts were tested for the oxidation of glycerol to lactic acid and their performance was compared with corresponding catalysts supported on TiO2?P25, TiO2-anatase and TiO2-rutile. Higher rates of reaction and higher selectivity to lactic acid were observed over nanocast TiO2 supported catalysts. The increased performance of these catalysts was attributed to the presence of Si on the surface of the support, which likely arose from inefficient etching of the SBA-15 template. The presence of Si in these catalysts was confirmed by X-ray photoelectron spectroscopy and electron energy loss spectroscopy. It was proposed that the residual Si present increases the Br?nsted acidity of the TiO2 support, which can lead to the formation of Lewis acid sites under reaction conditions; both sites are known to catalyse the dehydration of a primary alcohol in glycerol. Typically, under alkaline conditions, lactic acid is formed by the nucleophilic abstraction of a hydrogen. Thus, we propose that the improved selectivity to lactic acid over the nanocast TiO2 supported catalyst is attributed to the co-operation of heterogeneous and homogeneous dehydration reactions, as both compete directly with a direct oxidation pathway, which leads to the formation of oxidation products such as glyceric and tartronic acid.
- Douthwaite, Mark,Ford, Grayson,Garcia, Tomas,He, Qian,López, José Manuel,Morgan, David J.,Powell, Natasha,Sanahuja-Parejo, Olga,Solsona, Benjamin,Taylor, Aoife,Taylor, Stuart H.,Yang, Nating
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- Spinel copper-iron-oxide magnetic nanoparticles with cooperative Cu(i) and Cu(ii) sites for enhancing the catalytic transformation of 1,2-propanediol to lactic acid under anaerobic conditions
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The aerobic catalytic oxidation of 1,2-propanediol (PDO) over non-noble metal (e.g. Cu) based catalysts usually suffers serious C3 product dissociation at high temperature, thus showing low lactic acid (LA) selectivity. Here, an alternative anaerobic catalysis strategy over spinel copper-iron-oxide magnetic nanoparticles (CuFeOx MNs) with the coexistence of Cu(i) and Cu(ii) dual sites is developed for the catalytic transformation of PDO to LA with a quantitative yield of co-product H2 in basic aqueous solution. The absence of O2 is beneficial for enhancing LA production in comparison with the presence of O2. The synergy between Cu(i) and Cu(ii) sites in CuFeOx MNs is vital for improving the catalytic performance as compared to Cu2O or CuO catalysts with Cu(i) or Cu(ii) sites alone. Cu1Fe1Ox MNs with a Cu/Fe mole ratio of 1/1 exhibit 94.5% LA selectivity and 72.6% PDO conversion at 160 °C for 8 h. Experimental results and DFT calculations suggest that the spinel CuFeOx MN based catalytic PDO transformation follows a favorable pathway of PDO → hydroxyacetone → lactaldehyde → lactic acid for LA production. In addition to the catalytic PDO transformation, the use of CuFeOx MNs can be extended to favor high activity and selectivity in the catalytic transformation of glycerol to LA (98.5% selectivity) and ethylene glycol to glyceric acid (97.8% selectivity). This work highlights the design of an alternative non-noble metal-based CuFeOx MN catalyst for efficiently catalyzing the transformation of bio-based polyols into value-Added carboxylic acids.
- Feng, Yonghai,Liu, Lei,Lu, Congming,Meng, Minjia,Rao, Dewei,Wang, Huijie,Yin, Hengbo,Zhang, Yunlei
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p. 8094 - 8107
(2020/12/31)
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- Promotion of catalytic properties of vanillin loaded MCM-41 by Cu(I) and Cu(II) for enhanced removal of quinoline contaminants
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In the present study, to enhance removal of quinoline contaminants using natural active component, vanillin was loaded onto the MCM-41 (Mobile Component Material) nanoparticles in a simple way. The product was divided into two parts, which were improved by Copper(I) and Copper(II) salts. Promoted synthetic nanocatalysts (Cu(I)/Van./MCM-41, and Cu(II)/Van./MCM-41) were characterized using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-Ray Spectroscopy (EDS), Mapping, Fourier-Transform Infrared Spectroscopy (FTIR), and BET/BJH (Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH)) techniques. To reach optimal conditions, experimental design was performed using Response Surface Methodology (RSM). The experiments were done with the aid of nanocomposites, in presence of ultraviolet radiation without any auxiliary oxidants. Degradation percentages were measured by an Ultraviolet (UV) spectrophotometer. The products were identified using Gas Chromatography–Mass (GC-Mass) technique, and some mechanisms for quinoline removal were proposed. The results indicated that Cu (I) showed better performance in enhanced removal of quinoline than Cu(II).
- Arjmand, Mehdi,Fazaeli, Reza,Ghorbani, Mohammad Hossein,Kamani, Mina
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p. 4833 - 4841
(2020/09/16)
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- Toward glucuronic acid through oxidation of methyl-glucoside using PdAu catalysts
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The production of glucuronic acid via enzyme catalysis from biomass is slow. Here we studied the oxidation of methoxy-protected glucose (MG) using Pd-on-Au nanoparticle model catalysts to generate methoxy-protected glucuronic acid (MGA), a precursor to glucuronic acid. Pd-on-Au showed volcano-shape activity dependence on calculated Pd surface coverage (sc). The 80 sc% Pd-on-Au catalyst composition showed maximum initial turnover frequency (413 mol-MG mol-surface-atom?1 h?1) that was 5× higher than that of Au/C, while Pd/C was inactive. This Pd-on-Au composition gave the highest MGA yield (46%), supporting a bimetallic approach to glucuronic acid production.
- Yin, Y. Ben,Chen, Li,Heck, Kimberly N.,Zhang, Z. Conrad,Wong, Michael S.
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- Plasmonic Oxidation of Glycerol Using Au/TiO2 Catalysts Prepared by Sol-Immobilisation
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Abstract: Au nanoparticles supported on P25 TiO2 (Au/TiO2) were prepared by a facile sol-immobilisation method and investigated for the surface plasmon-assisted glycerol oxidation under base-free conditions. The Au/TiO2 samples were characterized by UV–vis spectroscopy and transmission electron microscopy. Catalysts were prepared using polyvinyl alcohol as stabiliser as well as in the absence of polymer stabiliser. Both the conversion and the reaction selectivity are affected by the plasmon-assisted oxidation and there is an interplay between the presence of the stabiliser and the Au nanoparticle size. Graphic Abstract: [Figure not available: see fulltext.].
- Abis, Laura,Dimitratos, Nikolaos,Sankar, Meenakshisundaram,Freakley, Simon J.,Hutchings, Graham J.
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- Electrochemical oxidation of amoxicillin on carbon nanotubes and carbon nanotube supported metal modified electrodes
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The electrolysis of amoxicillin (AMX) was carried out on CNT, Pt/CNT and Ru/CNT modified electrodes based on Carbon Toray in 0.1 M NaOH, 0.1 M NaCl and 0.1 M Na2CO3/NaHCO3 buffer (pH 10) media with the aim of studying the significance of two factors, electrode material and pH, on the oxidative degradation and mineralization of AMX. For this purpose, the electrolysis products were identified by HPLC-MS and GC–MS, and quantified by HPLC-UV-RID and IC. The highest carbon mineralization efficiency, corresponding to 30% of the oxidized AMX, was found for Pt/CNT modified electrode in carbonate buffer medium. Regarding to the AMX conversion, the results show that the effect of pH is higher than that of the electrode material. Principal component analysis allowed to determine the experimental parameters vs. product distribution relationship and to elucidate the oxidation pathways for the studied electrodes. The results show that the hydroxylation of the aromatic ring and the nitrogen atom play an important role on the efficient degradation of AMX.
- Ferreira, Marta,Kuzniarska-Biernacka, Iwona,Fonseca, António M.,Neves, Isabel C.,Soares, Olívia S.G.P.,Pereira, Manuel F.R.,Figueiredo, José L.,Parpot, Pier
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p. 322 - 331
(2019/07/10)
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- Preparation of AuPd/ZnO-CuO for the directional oxidation of glycerol to DHA
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Selective activation of the C-O bond of glycerol is a considerable challenge in current academic research. Herein, we fabricate an efficient AuPd/ZnO-CuO catalystviaa simple precipitation method and use it in the selective oxidation of glycerol (GLY) to produce dihydroxyacetone (DHA). Under base-free conditions, the AuPd/ZnO-CuO catalyst exhibits preferable catalytic performance compared with AuPd/ZnO and AuPd/CuO. The turnover frequency (TOF) of AuPd/ZnO-CuO reaches 687.1 h?1, which is 25 times that of AuPd/CuO and 6 times that of AuPd/ZnO. The AuPd/ZnO-CuO catalyst also shows good selectivity toward DHA and the highest DHA yield of 65.3%, which is at the top level among the reported results. Through STEM-EDS, XRD and Raman analyses, we find that ZnO-CuO is a composite oxide and that Zn and Cu elements in the ZnO-CuO support are uniformly distributed. Furthermore, HRTEM, EPR, and XPS results show that AuPd/ZnO-CuO has smaller AuPd alloy nanoparticles (NPs) but a higher concentration of surface defect sites compared with AuPd/ZnO and AuPd/CuO. Together with the catalytic performance and feasible mechanism, we consider that the enhanced performance of the AuPd/ZnO-CuO catalyst could be mainly ascribed to the rich surface defect sites, which facilitate the adsorption and activation of the secondary hydroxyl groups of glycerol.
- Zhao, Gengqiang,Wu, Guandong,Liu, Yanan,He, Yufei,Feng, Junting,Li, Dianqing
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p. 6223 - 6234
(2020/10/14)
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- Atomic-layer-deposited SnO2on Pt/C prevents sintering of Pt nanoparticles and affects the reaction chemistry for the electrocatalytic glycerol oxidation reaction
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Atomic layer deposition (ALD) is an efficient technique that allows atomic-level surface control of metal catalysts for the design and development of electrocatalytic materials. Herein, we report a strategy for efficient catalyst design using a particle ALD method to enhance the electrocatalytic glycerol-oxidation-reaction (GOR) performance. Atomically controlled thin SnO2 layers were deposited on a carbon-supported Pt nanoparticle (Pt/C) surface using the ALD technique. The resulting SnO2 overcoated Pt/C (ALD(SnO2)-Pt/C) was then heat-treated at 400 °C under a N2 atmosphere. The onset potential as a kinetic parameter decreased with ALD (SnO2) coatings. The turnover frequency (TOF) for the GOR showed similar values for the tested samples (TOF of Pt/C: 74.86 h-1 and TOF of ALD(SnO2)-Pt/C: 91.29 h-1). Interestingly, interactions between the ALD SnO2 overcoating and Pt nanoparticles improved the catalytic stability for the GOR, preventing sintering of Pt nanoparticle catalysts. This demonstrates that an ALD SnO2 coating on defect sites of Pt can diminish Pt sintering for the GOR. From the GOR in an electrochemical batch reactor, the ALD(SnO2)-Pt/C catalyst also generated more glyceraldehyde (GAD) product than uncoated Pt/C at a similar glycerol conversion level. The density functional theory (DFT) calculations suggest that the binding energies of glycerol and reaction intermediates change at the interface of the SnO2-coated Pt surface compared to those at the Pt surface only, thus affecting the reaction chemistry for the electrocatalytic GOR. This work highlights how we can control reaction performance measures such as catalytic stability and product selectivity by using the particle ALD technique for electrocatalytic reactions such as glycerol oxidation. This journal is
- Chang, Hyunju,Chung, Taek-Mo,Han, Hyunsu,Han, Jeong Hwan,Kim, Hyun Woo,Kim, Hyung Ju,Kim, Won Bae,Kim, Youngmin,Lee, Daewon
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supporting information
p. 15992 - 16005
(2020/10/02)
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- Selective oxidation of glycerol to tartronic acid over Pt/N-doped mesoporous carbon with extra framework magnesium catalysts under base-free conditions
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N-Doped mesoporous carbons (NMCs) with extra framework magnesium were prepared by a one-pot method and used as supports for Pt catalysts. The surface basicity of NMC improved in the presence of extra framework magnesium (e.g.,-Ph-O-Mg), meanwhile, the electron density of Pt was enriched by the electron transfer from graphitic N in NMC to Pt. As a result, the catalytic activity of the supported Pt catalyst was improved to be able to selectively oxidize glycerol (GLY) to tartronic acid (TA) under base-free conditions.
- Zhan, Tong,Liu, Weibing,Teng, Junjiang,Yue, Chaochao,Li, Dehao,Wang, Suhua,Tan, Hua
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supporting information
p. 2620 - 2623
(2019/03/05)
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- The Enhanced Catalytic Performance and Stability of Ordered Mesoporous Carbon Supported Nano-Gold with High Structural Integrity for Glycerol Oxidation
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Ordered mesoporous carbon (OMC) supported gold nanoparticles of size 3–4 nm having uniform dispersion were synthesized by sol-immobilization method. OMCs such as CMK-3 and NCCR-56 with high surface area and uniform pore size were obtained, respectively, using ordered mesoporous silicas such as SBA-15 and IITM-56 as hard templates, respectively. The resulting OMC supported monodispersed nano-gold, i. e., Au/CMK-3 and Au/NCCR-56, exhibited excellent performance as mild-oxidizing catalysts for oxidation of glycerol with high hydrothermal stability. Further, unlike activated carbon supported nano-gold catalysts (Au/AC), the OMC supported nano-gold catalysts, i. e., Au/CMK-3 and Au/NCCR-56, show no aggregation of active species even after recycling. Thus, in the case of Au/CMK-3 and Au/NCCR-56, both the fresh and regenerated catalysts showed excellent performane for the chosen reaction owing to an enhanced textural integrity of the catalysts and that with remarkable selectivity towards glyceric acid. The significance of the OMC supports in maintaining the dispersion of gold nanoparticles is explicit from this study, and that the activity of Au/AC catalyst is considerably decreased (~50 %) upon recycling as a result of agglomeration of the active gold nanoparticles over the disordered amorphous carbon matrix.
- Murthy, Palle R.,Selvam, Parasuraman
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p. 1913 - 1925
(2018/11/27)
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- Glycerol Partial Oxidation over Pt/Al2O3 Catalysts under Basic and Base-Free Conditions—Effect of the Particle Size
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The glycerol partial oxidation reaction over Pt/Al2O3 catalysts was studied under basic (NaOH/GLY molar ratio 4) and base-free conditions (NaOH/GLY molar ratio 0). Catalysts with small (2.95 nm) and large particle sizes (260.83 nm) were synthesized according to the use of different reducing agents, formaldehyde or sodium borohydride, and hydrazine, respectively. These different Pt particle sizes lead to a dramatic change in terms of activity, irrespective of the applied conditions. The biggest particles (i.e., 260 nm) seem to generate overoxidation products leading to a decrease in the carbon balance (to ~80%) while the smallest particles exhibit the highest initial glycerol transformation rate (i.e., ~10,000 mol h?1 molPt?1 under basic conditions at 60°C and ~2000 mol h?1 molPt?1 in the absence of a base at 100°C). In terms of selectivities, the main products are different as a function of the initial reaction conditions. For base-free conditions, the two main products are glyceraldehyde and glyceric acid with a sum of selectivities always larger than 80%. Under basic conditions, the major product is glyceric acid while no trace of glyceraldehyde is detected.
- Skrzyńska, El?bieta,El Roz, Ayman,Paul, Sébastien,Capron, Micka?l,Dumeignil, Franck
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- Catalyst for efficiently catalyzing production of glyceric acid from glycerin under alkali-free condition and production method of catalyst for efficiently catalyzing production of glyceric acid from glycerin under alkali-free condition
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The invention discloses a catalyst for efficiently catalyzing production of glyceric acid from glycerin under an alkali-free condition and a production method of the catalyst for efficiently catalyzing production of the glyceric acid from the glycerin under the alkali-free condition, and belongs to the technical field of multiphase catalytic conversion of biomass. The catalyst is composed of highly-dispersed PtM (M can be Ce, Cu, Mo, Zr, Mn, Fe or Bi) bi-metal and a composite metal oxide. According to the catalyst, firstly, M is reduced from the composite metal oxide, then M is loaded with a Pt salt, and through drying, the PtM bi-metal catalyst is obtained. Pt is highly dispersed and stable under the action of M, and production of the glyceric acid from the glycerin can be efficiently catalyzed. The catalyst is applied to a reaction for catalyzing production of the glyceric acid from the glycerin, reaction oxygen pressure is higher than 0 and equal to or lower than 5 MPa, the adding amount of the catalyst is more than 0 and equal to or less than 3 g, the substrate glycerin is 10-50 ml (0-1 mol/L), reaction temperature is 20-120 DEG C, the reaction is stable, and is carried out for more than 4 h, and the yield of the glyceric acid reaches 75%.
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Paragraph 0016; 0019; 0020; 0023; 0024; 0027; 0028; 0031
(2019/10/04)
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- Concise Asymmetric Synthesis of Kweichowenol A
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An asymmetric 11-step synthesis of the polyoxygenated cyclohexene natural product kweichowenol A from the traditional Chinese medicinal herb Uvaria kweichowesis is reported. The oxygenation pattern was installed on a linear precursor by exploiting the acyclic stereocontrol of the Kiyooka aldol reaction, as well as Cram chelate-controlled Grignard reactions. Ring-closing metathesis and a selective benzoylation then gave the natural product.
- Konrad, David B.,Kicin, Bilal,Trauner, Dirk
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supporting information
p. 383 - 386
(2019/02/26)
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- Efficient and stable platinum nanocatalysts supported over Ca-doped ZnAl2O4 spinels for base-free selective oxidation of glycerol to glyceric acid
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In the work, highly dispersed platinum nanocatalysts supported over undoped and Ca-doped zinc aluminate spinels were developed and applied for aqueous-phase selective oxidation of glycerol to produce glyceric acid under base-free conditions. As-fabricated Pt-based catalyst with the incorporation of an appropriate Ca/(Ca + Zn) molar ratio of 0.1 into the spinel exhibited a higher catalytic activity, along with a selectivity to glyceric acid (>81%) and a high turnover frequency of 1160 h?1, compared with other supported Pt-based ones over zinc aluminates, as well as most of supported Pt catalysts previously reported. The structural characterizations and catalytic experiments showed that surface synergy between highly dispersed metallic Pt0 species and medium-strength basic sites mainly contributed to its enhanced catalytic efficiency for base-free glycerol oxidation. Moreover, the present Pt catalyst also presented high structural stability and good reusability. The work opens an alternative approach for constructing highly efficient and stable metal-base bifunctional catalysts for a wide range of heterogeneous oxidation processes without the addition of liquid alkalis.
- Han, Zhengya,Xie, Renfeng,Song, Yihui,Fan, Guoli,Yang, Lan,Li, Feng
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- METHOD FOR PRODUCING CARBOXYLIC ACID
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PROBLEM TO BE SOLVED: To produce carboxylic acid from glycerol at a temperature lower than or equal to a boiling point of a solvent, using a catalyst that is easy to recover and reuse. SOLUTION: A method for producing carboxylic acid has a production step that produces carboxylic acid by a reaction between glycerol and oxygen-containing gas in the presence of a catalyst and an alkali metal. The catalyst is obtained through a mixture step for mixing a gold ion, a platinum ion, and a metal oxide in acidic liquid. The ratio of the mass of gold ions to the sum of the mass of gold ions and the mass of platinum ions is higher than 0.2 and lower than 0.8. SELECTED DRAWING: None COPYRIGHT: (C)2019,JPOandINPIT
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Paragraph 0021-0024; 0027
(2019/04/11)
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- Alcohols as Latent Hydrophobes: Entropically Driven Uptake of 1,2-Diol Functionalized Ligands by a Porous Capsule in Water
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Alcohols, with hydroxyl groups compositionally identical to water itself, are consummate hydrophiles, whose high solubilities preclude spontaneous self-assembly in water. Nevertheless, the solute-solvent interactions associated with their highly favorable solvation enthalpies impose substantial entropic costs, similar in magnitude to those that drive the hydrophobic assembly of alkanes. We now show that under nanoconfined conditions this normally dormant "hydrophobicity" can emerge as the driving force for alcohol encapsulation. Using a porous molecular capsule, the displacement of endohedrally coordinated formate ligands (HCO2-) by 1,2-hydroxyl-functionalized l-glycerate (l-gly, l-HOCH2(HO)CHCO2-) was investigated by van't Hoff analysis of variable-temperature 1H NMR in D2O. At pD 5.8, l-gly uptake is enthalpically inhibited. Upon attenuation of this unfavorable change in enthalpy by cosequestration of protons within the alcoholic environment provided by encapsulated diol-functionalized ligands, -TΔS° dominates over ΔH°, spontaneously filling the capsule to its host capacity of 24 l-gly ligands via an entropically driven hydrophobic response.
- Chakraborty, Sourav,Shnaiderman Grego, Alina,Garai, Somenath,Baranov, Mark,Müller, Achim,Weinstock, Ira A.
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supporting information
p. 9170 - 9174
(2019/06/21)
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- Selective Conversion of Cellulose to Hydroxyacetone and 1-Hydroxy-2-Butanone with Sn–Ni Bimetallic Catalysts
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The high-value-added chemicals hydroxyacetone (HA) and 1-hydroxy-2-butanone (HB) were produced from agricultural waste over a Ni3Sn4-SnOx catalyst. The Sn–Ni intermetallic compound and SnOx acted as the active sites for HA and HB production by selectively cleaving the target C?C and C?O bonds. Approximately 70 % of the total HA and HB yield was obtained by selective hydrogenolysis of cellulose. This strategy expands the application of cellulose towards renewable production of high-value C3 and C4 keto-alcohols from cellulosic biomass.
- Wang, Haiyong,Zhu, Changhui,Liu, Qiying,Tan, Jin,Wang, Chenguang,Liang, Zheng,Ma, Longlong
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p. 2154 - 2160
(2019/03/21)
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- Quantitative Determination of Pt- Catalyzed d -Glucose Oxidation Products Using 2D NMR
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Quantitative correlative 1H-13C NMR has long been discussed as a potential method for quantifying the components of complex reaction mixtures. Here, we show that quantitative HMBC NMR can be applied to understand the complexity of the catalytic oxidation of glucose to glucaric acid, which is a promising bio-derived precursor to adipic acid, under aqueous aerobic conditions. It is shown through 2D NMR analysis that the product streams of this increasingly studied reaction contain lactone and dilactone derivatives of acid products, including glucaric acid, which are not observable/quantifiable using traditional chromatographic techniques. At 98% glucose conversion, total C6 lactone yield reaches 44%. Furthermore, a study of catalyst stability shows that all Pt catalysts undergo product-mediated chemical leaching. Through catalyst development studies, it is shown that sequestration of leached Pt can be achieved through use of carbon supports.
- Armstrong,Hirayama,Knight,Hutchings
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p. 325 - 335
(2019/01/04)
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- Unraveling the mechanism of the oxidation of glycerol to dicarboxylic acids over a sonochemically synthesized copper oxide catalyst
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The utilization of low frequency ultrasound (US) offers a straightforward and powerful tool for the production of nanostructured materials, in particular for structurally stable, highly crystalline, and shape-controlled catalytic materials. Herein, we report an unconventional strategy for the synthesis of CuO nanoleaves within 5 min of US irradiation. The as-obtained CuO nanoleaves were found to be selective in the base-free aqueous oxidation of glycerol to dicarboxylic acids (78% yield of tartronic and oxalic acids), in the presence of hydrogen peroxide (H2O2) and under mild reaction conditions. Density Functional Theory (DFT) investigations revealed a synergy between the CuO catalyst and H2O2 in maintaining the structural integrity of the catalyst during the reaction, creating alternative efficient pathways for the selective formation of dicarboxylic acids. Isotope labeling experiments using H218O2 further confirmed that oxygen from hydrogen peroxide, not from CuO, was preferentially incorporated into the dicarboxylic acid, significantly preserving the monoclinic structure of the CuO catalyst.
- Amaniampong, Prince N.,Trinh, Quang Thang,Varghese, Jithin John,Behling, Ronan,Valange, Sabine,Mushrif, Samir H.,Jér?me, Francois
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supporting information
p. 2730 - 2741
(2018/06/29)
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- Gold-Doped Fe/TiO2 Catalysts: A Case of Extra-Low Gold Loading in Glycerol Oxidation
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Abstract: Au/Fe/TiO2 catalysts with a low Au content ( 16 000.
- Redina,Vikanova,Shesterkina,Kustov
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p. 2143 - 2147
(2018/10/24)
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- Promoting effect of solvent on Cu/CoO catalyst for selective glycerol oxidation under alkaline conditions
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Cu/CoO catalysts were employed for the selective oxidation of glycerol in the aqueous phase under basic conditions. The effect of the solvent on the catalytic performance was investigated and the impact on the catalyst was thoroughly elucidated. Detailed characterization of the catalysts by HR-TEM, XRD, and XPS analysis before and after the reaction revealed that the addition of co-solvents (ethanol, n-propanol, or tert-butanol) drastically altered the catalyst properties. In particular, the amount of the catalytically active CoO(OH) phase generated during the reaction depends on the co-solvent used. Generally, the co-solvent has a beneficial effect on the catalytic activity and improves the glycerol conversion by a factor of up to 1.8, which could be linearly correlated to the ET(30) solvent polarity.
- Dodekatos, Georgios,Ternieden, Jan,Schünemann, Stefan,Weidenthaler, Claudia,Tüysüz, Harun
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p. 4891 - 4899
(2018/10/24)
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- Glycerol Oxidation Using MgO- and Al2O3-supported Gold and Gold–Palladium Nanoparticles Prepared in the Absence of Polymer Stabilizers
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Au and AuPd nanoparticles supported on MgO and Al2O3 were employed for the selective aqueous phase oxidation of glycerol under basic conditions. Catalysts were prepared by sol-immobilization without the addition of a stabilizing agent such as polyvinyl alcohol (PVA), which is generally added to stabilize the noble metal sol prior to immobilization. The obtained materials prepared with and without stabilizing agent were active for glycerol oxidation and showed similar catalytic performances—implying that the stabilizing polymer is not required to obtain active materials. Depending on the support used, it was possible to tailor the selectivity towards the desired oxidation products by using catalysts prepared with or without stabilizing agent. PVA-free Au/γ-Al2O3 exhibited a remarkably high selectivity towards tartronic acid (40 % at 97 % conversion), which was not observed for Au/γ-Al2O3 prepared with PVA (27 % at isoconversion). Selective glycerol oxidation performed under base-free conditions over AuPd/MgO catalysts also corroborated the previous results that the presence of a stabilizing polymer is not required to prepare active catalysts by sol-immobilization. Thus, a facile way to circumvent the inherent drawbacks encountered by the use of polymer stabilizers during catalyst preparation is presented herein. Experimental results suggest that the presence of the polymer stabilizers can affect the reaction pathways and control selectivity.
- Dodekatos, Georgios,Abis, Laura,Freakley, Simon J.,Tüysüz, Harun,Hutchings, Graham J.
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p. 1351 - 1359
(2018/03/30)
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- Samholides, Swinholide-Related Metabolites from a Marine Cyanobacterium cf. Phormidium sp.
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Cancer cell cytotoxicity was used to guide the isolation of nine new swinholide-related compounds, named samholides A-I (1-9), from an American Samoan marine cyanobacterium cf. Phormidium sp. Their structures were determined by extensive analysis of 1D and 2D NMR spectroscopic data. The new compounds share an unusual 20-demethyl 44-membered lactone ring composed of two monomers, and they demonstrate structural diversity arising from geometric isomerization of double bonds, sugar units with unique glyceryl moieties and varied methylation patterns. All of the new samholides were potently active against the H-460 human lung cancer cell line with IC50 values ranging from 170 to 910 nM. The isolation of these new swinholide-related compounds from a marine cyanobacterium reinvigorates questions concerning the evolution and biosynthetic origin of these natural products.
- Tao, Yiwen,Li, Pinglin,Zhang, Daojing,Glukhov, Evgenia,Gerwick, Lena,Zhang, Chen,Murray, Thomas F.,Gerwick, William H.
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p. 3034 - 3046
(2018/03/25)
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- Chemical constituents and biological activities of Viburnum macrocephalum f. keteleeri
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Three new compounds (1–3) and seven known compounds (4–10) have been isolated from the ethanolic extract of Viburnum macrocephalum f. keteleeri using bioactivity-guided fractionation and identified as methyl (2-α-L-rhamnopyranosyloxy)acetate (1), methyl (2R-3-α-L-rhamnopyranosyloxy)glycerate (2), methyl (3R-4-α-L-rhamnopyranosyloxy-3-hydroxy)butanoate (3), bridelionoside B (4), (6S,7E,9R)-roseoside (5), linarionoside A (6), 3,7,11-trimethyl-1,6-dodecadien-3,10,11-triol (7), (+)-8-hydroxylinalool (8), β-sitosterol (9) and daucosterol (10). The structures of 1–3, including absolute configurations, were determined by spectroscopic data (1H and 13C NMR, HSQC, HMBC and ORD) and chemical methods. In addition, compounds 1–8 were assayed for their insecticidal and antimicrobial activities. Compounds 7 and 8 exhibited moderately insecticidal effects against Mythimna separata with LD50 values of 180 and 230?μg?g?1, respectively. Compounds 2, 3, 7 and 8 showed varying antimicrobial activities with IC50 values ranging from 125 to 529?μM.
- Shao, Jian-Hua,Chen, Jia,Xu, Xiao-Qing,Zhao, Chun-Chao,Dong, Zi-Ling,Liu, Wen-Yan,Shen, Jie
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- Synthesis of Phosphatidylserine and Its Stereoisomers: Their Role in Activation of Blood Coagulation
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Natural phosphatidylserine (PS), which contains two chiral centers, enhances blood coagulation. However, the process by which PS enhanced blood coagulation is not completely understood. An efficient and flexible synthetic route has been developed to synthesize all of the possible stereoisomers of PS. In this study, we examined the role of PS chiral centers in modulating the activity of the tissue factor (TF)-factor VIIa coagulation initiation complex. Full length TF was relipidated with phosphatidylcholine, and the synthesized PS isomers were individually used to estimate the procoagulant activity of the TF-FVIIa complex via a FXa generation assay. The results revealed that the initiation complex activity was stereoselective and had increased sensitivity to the configuration of the PS glycerol backbone due to optimal protein-lipid interactions.
- Mallik, Suman,Prasad, Ramesh,Bhattacharya, Anindita,Sen, Prosenjit
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supporting information
p. 434 - 439
(2018/05/23)
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- Synthesis of macrocyclic precursors of the vioprolides
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The vioprolides are novel depsipeptides that have not been synthesized. However, they have been identified as important targets for synthesis because of their novel biological activities and challenging chemical structures. Following early work on the synthesis of a modified tetrapeptide that contained both the (E)-dehydrobutyrine and thiazoline components of vioprolide D, problems were encountered in taking an (E)-dehydrobutyrine containing intermediate further into the synthesis. A second approach to vioprolides and analogues was therefore investigated in which (E)- and (Z)-dehydrobutyrines were to be introduced by selenoxide elimination very late in the synthesis. A convergent approach to advanced macrocyclic precursors of the vioprolides was then completed using a modified hexapeptide and a dipeptidyl glycerate. In this work, it was necessary to protect the 2-hydroxyl group of the glycerate as its acetate and not as its 2,2,2-trichloroethoxycarbonate. Preliminary studies were carried out on the introduction of the required dehydrobutyrine and thiazoline components into advanced intermediates.
- Butler, Eibhlin,Florentino, Lucia,Cornut, Damien,Gomez-Campillos, Gonzalo,Liu, Hao,Regan, Andrew C.,Thomas, Eric J.
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p. 6935 - 6960
(2018/10/17)
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- HETEROGENEOUS CATALYST FOR PREPARING ACRYLIC ACID, AND ACRYLIC ACID PREPARATION METHOD USING SAME
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The present disclosure relates to a catalyst used in the preparation of acrylic acid and acrylic acid preparation method using the same, and more specifically, discloses a catalyst capable of enhancing selectivity of acrylic acid and a production yield of acrylic acid when preparing acrylic acid from allyl alcohol using a heterogeneous catalyst including bimetallic alloy catalyst particles of gold and another metal, and an acrylic acid preparation method using the same.
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Paragraph 0089; 0090; 0091; 0092; 0094; 0116
(2018/08/03)
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- The Role of Mg(OH)2 in the So-Called “Base-Free” Oxidation of Glycerol with AuPd Catalysts
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Mg(OH)2- and Mg(OH)2-containing materials can provide excellent performance as supports for AuPd nanoparticles for the oxidation of glycerol in the absence of base, which is considered to be a result of additional basic sites on the surface of the support. However, its influence on the reaction solution is not generally discussed. In this paper, we examine the relationship between the basic Mg(OH)2 support and AuPd nanoparticles in detail using four types of catalyst. For these reactions, the physical interaction between Mg(OH)2 and AuPd was adjusted. It was found that the activity of the AuPd nanoparticles increased with the amount of Mg(OH)2 added under base-free conditions, regardless of its interaction with the noble metals. In order to investigate how Mg(OH)2 affected the glycerol oxidation, detailed information about the performance of AuPd/Mg(OH)2, physically mixed (AuPd/C+Mg(OH)2) and (AuPd/C+NaHCO3) was obtained and compared. Furthermore, NaOH and Mg(OH)2 were added during the reaction using AuPd/C. All these results indicate that the distinctive and outstanding performance of Mg(OH)2 supported catalysts in base-free condition is in fact directly related to its ability to affect the pH during the reaction and as such, assists with the initial activation of the primary alcohol, which is considered to be the rate determining step in the reaction.
- Fu, Jile,He, Qian,Miedziak, Peter J.,Brett, Gemma L.,Huang, Xiaoyang,Pattisson, Samuel,Douthwaite, Mark,Hutchings, Graham J.
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supporting information
p. 2396 - 2402
(2018/02/06)
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- A comparison of entrapped and covalently bonded laccase: Study of its leakage, reusability, and the catalytic efficiency in TEMPO-mediated glycerol oxidation
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This article presents the comparison for reusability and leakage between entrapped and covalently bonded laccase and their performances towards the selective oxidation of glycerol. The reusability of immobilized laccase enzyme was studied by reacting a batch of immobilized laccase with ABTS for 15 cycles. The investigation of the leakage of immobilized laccase was carried out by storing the immobilized laccase in acetate buffer solution for 32 days. The data show that the retained enzyme activities of entrapped and covalently bonded enzyme after being reused for eight cycles were well above 60% and the leakages after storing for a month in the acetate buffer at 4 °C were well below 15%. The entrapped laccase coupled with TEMPO was found to perform better and gave a two-fold higher yield of glyceraldehyde and glyceric acid in the selective oxidation of glycerol compared to covalently bonded laccase. Hence, physical entrapment of laccase would be a suitable immobilization method in the laccase-mediated selective oxidation of glycerol.
- Hong, Chi Shein,Lau, Cindy Chin Yee,Leong, Chun Yi,Chua, Gek Kee,Chin, Sim Yee
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p. 352 - 361
(2017/10/23)
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- Effect of Post-Treatment on Structure and Catalytic Activity of CuCo-based Materials for Glycerol Oxidation
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A series of CuCo-based materials prepared by co-precipitation with varied Co/Cu ratios and different post-treatments were applied in the selective oxidation of glycerol in the aqueous phase under basic conditions. The influence of the post-treatment on the structure of the materials and the catalytic performance was investigated in detail. As-prepared materials without calcination and materials calcined under air with subsequent reduction under ethanol/N2 gas stream showed higher conversion of glycerol compared to samples solely calcined under air or to samples calcined under air with subsequent reduction under H2/Ar gas stream. The main products identified in the liquid phase were glyceric, glycolic, and formic acids. Systematic catalytic studies for differently prepared samples with varied Cu content and subsequent characterization of the materials by N2 physisorption, XRD, TEM, and EDX allowed for the identification of CoO(OH) in contact with CuO as the potentially active phases.
- Dodekatos, Georgios,Tüysüz, Harun
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p. 610 - 619
(2017/02/26)
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- A switchable route to valuable commodity chemicals from glycerol via electrocatalytic oxidation with an earth abundant metal oxidation catalyst
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Electrocatalytic upgrading of glycerol to value-added commodity is demonstrated using an ultralow loading of a cobalt-based oxidation catalyst at 16 μg cm-2. Reactions take place under ambient conditions in an aqueous environment, while generating H2 as a byproduct. Selectivity towards two major products, lactic acid and glyceric acid, can be controlled via simple variation of reaction conditions. The system is scalable and functions well even in the presence of methanol, an impurity commonly found in the industrial bio-diesel waste stream. Industrial glycerol waste from a local bio-diesel plant was also shown to be upgradable after a simple aqueous pretreatment.
- Lam, Chun Ho,Bloomfield, Aaron J.,Anastas, Paul T.
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p. 1958 - 1968
(2017/06/09)
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- Prebiotic synthesis of phosphoenol pyruvate by α-phosphorylation-controlled triose glycolysis
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Phosphoenol pyruvate is the highest-energy phosphate found in living organisms and is one of the most versatile molecules in metabolism. Consequently, it is an essential intermediate in a wide variety of biochemical pathways, including carbon fixation, the shikimate pathway, substrate-level phosphorylation, gluconeogenesis and glycolysis. Triose glycolysis (generation of ATP from glyceraldehyde 3-phosphate via phosphoenol pyruvate) is among the most central and highly conserved pathways in metabolism. Here, we demonstrate the efficient and robust synthesis of phosphoenol pyruvate from prebiotic nucleotide precursors, glycolaldehyde and glyceraldehyde. Furthermore, phosphoenol pyruvate is derived within an α-phosphorylation controlled reaction network that gives access to glyceric acid 2-phosphate, glyceric acid 3-phosphate, phosphoserine and pyruvate. Our results demonstrate that the key components of a core metabolic pathway central to energy transduction and amino acid, sugar, nucleotide and lipid biosyntheses can be reconstituted in high yield under mild, prebiotically plausible conditions.
- Coggins, Adam J.,Powner, Matthew W.
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p. 310 - 317
(2017/04/03)
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- Metal-Free Oxidation of Glycerol over Nitrogen-Containing Carbon Nanotubes
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Nitrogen rich carbon nanotubes have been used as a metal free catalyst for the conversion of glycerol into dihydroxyacetone using tert-butyl hydroperoxide as an oxidant. Pyridine nitrogen groups embedded in a carbon matrix are identified as active sites for the reaction. Computational studies have demonstrated that oxidation of pyridine groups to pyridine oxime followed by hydrogen abstraction from secondary alcohol is likely responsible for the oxidation process.
- Gupta, Neeraj,Khavryuchenko, Oleksiy,Villa, Alberto,Su, Dangsheng
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p. 3030 - 3034
(2017/08/18)
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- Lattice distortion induced electronic coupling results in exceptional enhancement in the activity of bimetallic PtMn nanocatalysts
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Lattice strain plays a critical role in structural heterogeneity and surface electronic properties of bimetallic nanocatalysts. However, understanding of how to engineer optimal electron transfer in anisotropic bimetallic crystals remains a grand challenge to achieve enhanced catalytic performances. We investigate beyond conventional polymer based core-shell and alloy structures, and present unique lattice distorted PtMn catalysts fabricated via a cooperative self-assembly method. The strong internal strain between Pt and Mn lattices is found to induce the structural distortion of anisotropic PtMn crystals and formation of asymmetric flower shapes, leading to stretched Pt and contracted Mn lattices. Such distorted bimetallic crystals exhibit unusual electronic coupling and an eight-fold synergistic enhancement in catalytic oxidation of renewable biomass feedstocks compared with monometallic Pt catalysts. The novel synthesis technique and revealed electronic coupling mechanism described herein opens the door for the rational discovery of other bimetallic nanocatalysts with positive synergy.
- Jin, Xin,Zeng, Chun,Yan, Wenjuan,Zhao, Meng,Bobba, Pallavi,Shi, Honghong,Thapa, Prem S.,Subramaniam, Bala,Chaudhari, Raghunath V.
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- Selective glycerol oxidation using platinum nanoparticles supported on multi-walled carbon nanotubes and nitrogen-doped graphene hybrid
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Selective oxidation of glycerol is a hot topic. Increased biodiesel production has led to glycerol oxidation over Au- and Pt-based catalysts being widely studied. However, Pt catalysts suffer from deactivation because of weak metal-support interactions. In this study, multi-walled carbon nanotube (MWCNTs)-pillared nitrogen-doped graphene (NG) was prepared by direct pyrolysis of melamine on MWCNTs, and the synthesized NG-MWCNT composite was used as the support for Pt. Characterization results showed that the surface area (173 m2/g) and pore volume of the NG-MWCNT composite were greater than those of bare MWCNTs and the separated melamine pyrolysis product (CNx). Pt (1.4 ± 0.4 nm) dispersion on the NG-MWCNTs was favorable and the Pt/NG-MWCNT catalyst was highly active and selective in the oxidation of glycerol to glyceric acid (GLYA) in base-free aqueous solution. For example, the conversion of glycerol reached 64.4% with a GLYA selectivity of 81.0%, whereas the conversions of glycerol over Pt/MWCNTs and Pt/CNx were 29.0% and 31.6%, respectively. The unique catalytic activity of the Pt/NG-MWCNTs is attributed to well-dispersed Pt clusters on the NG-MWCNTs and the electron-donating effect of the nitrogen dopant in the NG-MWCNTs.
- Zhang, Mengyuan,Sun, Yanyan,Shi, Juanjuan,Ning, Wensheng,Hou, Zhaoyin
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p. 537 - 544
(2017/04/04)
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- One-step synthesis of pyruvic acid from glycerol oxidation over Pb promoted Pt/activated carbon catalysts
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One-step production of pyruvic acid through selective oxidation of glycerol was investigated using lead promoted platinum/activated carbon (Pb-Pt/AC) catalysts under mild conditions. The results of N2 physisorption, X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy revealed that the alloy phases of PtPb and PtxPb were favorable for pyruvic acid production from glycerol oxidation, whereas the Pb3(CO3)2(OH)2 and surface Pb0 species inhibited the glycerol conversion. The loading of Pb and the catalyst preparation method (including impregnation and deposition precipitation) affected the formation of different metal species. Pyruvic acid was obtained at a yield of 18.4% on a 5.0 wt% Pb-5.0 wt% Pt/AC catalyst prepared by co-deposition precipitation method and 500 °C argon treatment.
- Zhang, Chen,Wang, Tao,Ding, Yunjie
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p. 928 - 937
(2017/05/22)
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- Au/CuMgAl-hydrotalcite catalysts promoted by Cu+ and basic sites for selective oxidation of glycerol to dihydroxyacetone
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CuMgAl-hydrotalcite-supported Au catalysts were prepared and tested in the selective conversion of glycerol to dihydroxyacetone. The electron density of Au was decreased by Cu embedded in the supports, arising from the electron transfer from Au to Cu sites. The valence state (+?1) of Cu ions was detected. Both Cu+ and basic sites (Mg–O) affected the catalytic activity of Au catalysts. The Cu+ sites promoted the selective oxidation of glycerol to dihydroxyacetone, while basic sites boosted the selectivity oxidation of glycerol to glyceric acid. The synergy of Cu+ sites and basic sites could effectively promote the activity and selectivity of Au catalysts in the selectively conversion of glycerol to dihydroxyacetone. A 53% conversion of glycerol and 72% of dihydroxyacetone selectivity were obtained under optimum reaction conditions.
- Yin, Yanrui,Tang, Tian,Xu, Chunli
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p. 319 - 326
(2017/12/12)
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