- Activated carbon aerogel supported copper catalysts for the hydrogenation of methyl acetate to ethanol: Effect of KOH activation
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Methyl acetate (MA) hydrogenation is crucial for indirect ethanol synthesis through syngas (CO + H2). In our work, activated carbon aerogel supported copper (Cu-ACA) catalysts have been prepared by a conventional impregnation method. The surface area and functional groups of the ACA soared after KOH activation. The highest surface area achieved for the ACA was 2562 m2 g-1. The anchoring effect of micropores and external oxygen-containing groups (OCGs) significantly enhanced the metal-support interaction in catalysts, facilitating the high dispersion of Cu and an enhancement in surface Cu+ species, both of which improved the catalytic activity of catalysts. Cu-ACA-A4 showed the most outstanding catalytic performance, with a MA conversion of 95.2% and an ethanol selectivity of 62.2%, close to the carbon equilibrium selectivity of 66.7%.
- Hou, Xiaoxiong,Zhao, Jinxian,Liu, Junjie,Han, Yahong,Pei, Yongli,Ren, Jun
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- ESI-MS Insights into Acceptorless Dehydrogenative Coupling of Alcohols
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Acceptorless dehydrogenative coupling (ADC) reactions catalyzed by a series of Ru and Os complexes were studied by ESI-MS. Important ethoxo, 1-ethoxyethanolate, and hydride intermediates were intercepted in the ADC of ethanol to ethyl acetate. Collision-induced dissociation (CID) experiments were applied as a structure elucidation tool and as a probe of the propensity of the reaction intermediates to evolve acetaldehyde, ethyl acetate, and H2, relevant to the catalytic cycle. The key mechanistic step producing ethyl acetate from the 1-ethoxyethanolate intermediates was documented. Energy-dependent CID experiments demonstrated the importance of a vacant coordination site for efficient production of ethyl acetate. The versatility and potential broad applicability of ESI-MS and its tandem version with CID was further illustrated for the ADC reaction of alcohols with amines, affording amides. A mechanism related to that found for the ester synthesis is plausible, with the key step involving formation of a hemiaminaloxide intermediate.
- Vicent, Cristian,Gusev, Dmitry G.
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- THERMAL DECOMPOSITION OF PEROXIDE DERIVATIVES OF POLYFLUORINATED β-KETOESTERS
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The thermal flow microcalorimetric method was used to determine the kinetic parameters for the thermal decomposition of peroxide derivatives of polyfluorinated β-ketoesters and the decomposition products were established.
- Rakhimov, A. I.,Chapurkin, V. V.,Val'dman, A. I.,Val'dman, D. I.,Saloutin, V. I.,et al.
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- Total oxidation of ethanol over Au/Ce0.5Zr0.5O2 cordierite monolithic catalysts
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The aim of this work was to propose the methods for gold introduction during the preparation of monolithic catalysts and to investigate their effect on catalyst properties. Two types of catalysts were prepared: (i) monoliths washcoated with gold/ceria-zirconia powder, and (ii) gold deposited on the monoliths washcoated with ceria-zirconia powder. An important part of the work was the characterization of the catalysts, in particular Au particle size and redox properties. Catalytic performance and selectivity were evaluated using ethanol gas-phase oxidation. It was shown that the enhanced reducibility of the catalysts with higher Au dispersion leads to improved catalytic performance.
- Topka, Pavel,Klementová, Mariana
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- Iodide-induced differential control of metal ion reduction rates: synthesis of terraced palladium-copper nanoparticles with dilute bimetallic surfaces
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Metal nanoparticles possessing a high density of atomic steps and edge sites provide an increased population of undercoordinated surface atoms, which can enhance the catalytic activity of these materials compared to low-index faceted or bulk materials. Simply increasing reactivity, however, can lead to a concurrent increase in undesirable, non-selective side products. The incorporation of a second metal at these reactive stepped features provides an ideal avenue for finely attenuating reactivity to increase selectivity. A major challenge in synthesizing bimetallic nanomaterials with tunable surface features that are desirable for fundamental catalytic studies is a need to bridge differences in precursor reduction potentials and metal lattice parameters in structures containing both a noble metal and a non-noble metal. We report the use of low micromolar concentrations of iodide ions as a means of differentially controlling the relative reduction rates of a noble metal (palladium) and a non-noble metal (copper). The iodide in this system increases the rate of reduction of palladium ions while concurrently slowing the rate of copper ion reduction, thus providing a degree of control that is not achievable using most other reported means of tuning metal ion reduction rate. This differential control of metal ion reduction afforded by iodide ions enables access to nanoparticle growth conditions in which control of palladium nanoparticle growth by copper underpotential deposition becomes possible, leading to the generation of unique terraced bimetallic particles. Because of their bimetallic surface composition, these terraced nanoparticles exhibit increased selectivity to acetaldehyde in gas phase ethanol oxidation.
- King, Melissa E.,Personick, Michelle L.
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- Kinetics of ethanol dehydrogenation into ethyl acetate
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The kinetics of gas-phase dehydrogenation of ethanol into ethyl acetate over a copper-zinc-chromium catalyst has been investigated in a flow reactor at pressures of 10-20 atm and temperatures of 230-290 C. For the process occurring under kinetic control, the rate constants of two reactions and the adsorption constants of five components have been determined using the Langmuir-Hinshelwood model. A kinetic model has been developed for the process. This model provides means to design a reactor for dehydrogenation of ethanol into ethyl acetate in different regimes.
- Men'Shchikov,Gol'Dshtein,Semenov
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- Acetic acid hydrogenation over supported platinum catalysts
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The kinetic behavior of acetic acid hydrogenation over platinum supported on TiO2, SiO2, η-Al2O3, and Fe2O3 was studied in a differential, fixed-bed reactor at 423-573 K, 100-700 torr hydrogen, and 7-50 torr acetic acid. The interaction of acetic acid with the oxide support played a major role in determining the kinetics of the reaction, and platinum served as a source of mobile, activated hydrogen atoms. During hydrogenation at low conversions, carbon-containing products consisted of about 50% CO and 50% CH4 over Pt/SiO2; 50% ethanol, 30% ethyl acetate, and 20% ethane over Pt/TiO2 reduced at 473 or 773 K; 40% CH4, 10% ethane, 8% ethanol, 4% ethyl acetate, 33% CO, and 5% CO2 over Pt/η-Al2O3; and 80% acetaldehyde and 20% ethanol over Pt/Fe2O3. Pt/TiO2 catalysts were the most active, with activities and turnover frequencies being ≤ 2 orders of magnitude larger than those for the other catalysts. The apparent reaction order with respect to H2 varied between 0.4 and 0.6, while that with respect to acetic acid was 0.2-0.4. This study provided evidence that acetic acid hydrogenation over supported Pt catalysts can be described by a Langmuir-Hinshelwood-type mechanism invoking two sites, one on the metal to activate H2 and one on the oxide to molecularly adsorb acetic acid. The kinetic rate expression derived from this reaction model fitted the data well with thermodynamically consistent parameters.
- Rachmady,Vannice
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- Acetic acid hydrogenation to ethanol over supported Pt-Sn catalyst: Effect of Bronsted acidity on product selectivity
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Gas phase hydrogenation of acetic acid was investigated over a series of SiO2-Al2O3 supported platinum-tin (Pt-Sn) catalysts. The active metals were impregnated over the support using incipient wetness technique and the resulting catalyst samples were characterized by Transmission electron microscopy, Hydrogen pulse chemisorption, BET surface area analyzer, Powder X-Ray diffraction, NH3-Temperature programmed desorption and H2-Temperature programmed reduction methods. Acetic acid hydrogenation reaction was carried out in an isothermal fixed bed catalyst testing unit. The results revealed that bimetallic Pt-Sn catalyst forms Pt-Sn alloy upon reduction which favors acetic acid hydrogenation to ethanol compared to competing side product CH4. The magnitude of Pt-Sn alloy formed per unit mass of catalyst depends upon the Pt/ Sn molar ratio in the calcined catalyst sample. 3 wt% Pt- 3 wt% Sn on SiO2-Al2O3 was found to be the optimum catalyst loading, resulting in 81% acetic acid conversion with 95% ethanol selectivity at 2 MPa and 270 °C. Further increase in ethanol selectivity would require prevention of esterification of acetic acid with ethanol, which leads to formation of ethyl acetate as by-product. The effect of catalyst acidity on acetic acid conversion and ethanol selectivity was studied and it was observed that proton donating capability of the support leads to the formation of ethyl acetate as by-product which, in turn, reduces ethanol selectivity. The ethanol synthesis reaction and esterification reaction over Bronsted acid sites takes place in series. The rate of esterification reaction was found to be highly dependent on the Bronsted acid density of the catalysts. Other catalyst parameters have little role on ethyl acetate yield.
- Rakshit, Pranab Kumar,Voolapalli, Ravi Kumar,Upadhyayula, Sreedevi
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- Role of the Cu-ZrO2 Interfacial Sites for Conversion of Ethanol to Ethyl Acetate and Synthesis of Methanol from CO2 and H2
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Well-defined Cu catalysts containing different amounts of zirconia were synthesized by controlled surface reactions (CSRs) and atomic layer deposition methods and studied for the selective conversion of ethanol to ethyl acetate and for methanol synthesis. Selective deposition of ZrO2 on undercoordinated Cu sites or near Cu nanoparticles via the CSR method was evidenced by UV-vis absorption spectroscopy, scanning transmission electron microscopy, and inductively coupled plasma absorption emission spectroscopy. The concentrations of Cu and Cu-ZrO2 interfacial sites were quantified using a combination of subambient CO Fourier transform infrared spectroscopy and reactive N2O chemisorption measurements. The oxidation states of the Cu and ZrO2 species for these catalysts were determined using X-ray absorption near edge structure measurements, showing that these species were present primarily as Cu0 and Zr4+, respectively. It was found that the formation of Cu-ZrO2 interfacial sites increased the turnover frequency by an order of magnitude in both the conversion of ethanol to ethyl acetate and the synthesis of methanol from CO2 and H2.
- Ro, Insoo,Liu, Yifei,Ball, Madelyn R.,Jackson, David H. K.,Chada, Joseph Paul,Sener, Canan,Kuech, Thomas F.,Madon, Rostam J.,Huber, George W.,Dumesic, James A.
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- A green approach to ethyl acetate: Quantitative conversion of ethanol through direct dehydrogenation in a Pd-Ag membrane reactor
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Pincers do the trick: The conversion of ethanol to ethyl acetate and hydrogen was achieved using a pincer-Ru catalyst in a Pd-Ag membrane reactor. Near quantitative conversions and yields could be achieved without the need for acid or base promoters or hydrogen acceptors (see scheme).
- Zeng, Gaofeng,Chen, Tao,He, Lipeng,Pinnau, Ingo,Lai, Zhiping,Huang, Kuo-Wei
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- Catalytic Conversion of Ethanol to n-Butanol Using Ruthenium P-N Ligand Complexes
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We report several ruthenium catalysts incorporating mixed donor phosphine-amine ligands for the upgrade of ethanol to the advanced biofuel n-butanol, which show high selectivity (≥90%) at good (up to 31%) conversion. In situ formation of catalysts from mixtures of [RuCl2(η6-p-cymene)]2 and 2-(diphenylphosphino)ethylamine (1) shows enhanced activity at initial water concentrations higher than those of our previously reported diphosphine systems. Preliminary mechanistic studies (electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy) suggest the possibility of ligand-assisted proton transfer in some derivatives.
- Wingad, Richard L.,Gates, Paul J.,Street, Steven T. G.,Wass, Duncan F.
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- Selective oxidation of ethanol over Ag, Cu and Au nanoparticles supported on Li2O/Γ-Al2O3
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In an effort to verify a previous striking report that ethanol could be oxidized selectively to ethylene oxide, ethanol oxidation on Ag, Cu, or Au nanoparticles supported on Li2O/γ-Al2O3 or γ-Al2O3 was examined between 100 and 400 °C. Ag and Cu catalysts were found to be highly selective to acetaldehyde (>95% on Ag below 325 °C and on Cu below 250 °C). On Au, selectivities to acetaldehyde were lower, with higher selectivity to ethyl acetate and acetic acid. No ethylene oxide was observed under any conditions. Our results, including selectivity variations among these metals, are consistent with previous studies of ethanol oxidation over coinage metals supported on γ-Al2O3, with no changes in primary product identity and minor changes in selectivity upon addition of Li2O. Unfortunately, these results are in direct contradiction to previous work reporting the desirable direct conversion of ethanol to ethylene oxide on Ag, Cu, and Au on Li2O/γ-Al2O3.
- Silbaugh, Trent L.,Devlaminck, Pierre,Sofranko, John A.,Barteau, Mark A.
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- Catalytic Transformation of Ethanol over Microporous Vanadium Silicate Molecular Sieves with MEL Structure (VS-2)
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The transformation of ethanol was carried out over vanadium silicate molecular sieves with MEL topology (VS-2) with different Si/V atomic ratios in the temperature range 523-623 K. The reaction was performed in a fixed-bed down-flow reactor at atmospheric pressure. Acetaldehyde, diethyl ether, and ethylene were the major products along with small amounts of acetone, acetic acid, ethyl acetate, and carbon oxides. The conversion increased while the selectivity toward acetaldehyde decreased with increase in reaction temperature. The kinetics of the reaction (at 5% conversion) indicated a nearly first-order dependence of the rate of formation of the major products on ethanol. The formation of acetaldehyde is suggested to be mainly through the involvement of the vanadyl species (V=O) while diethyl ether production is controlled by the simultaneous involvement of V=O and V-O-Si associated with vanadium in the lattice. The intrinsic activity of vanadium incorporated into the zeolite framework is nearly 10 times that of the vanadium present in the impregnated sample. The nature of the sites involved in the formation of the different products, as elucidated from spectroscopic techniques (NMR and ESR), and the possible reaction mechanisms are proposed.
- Kannan,Sen,Sivasanker
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- Structural requirements and reaction pathways in condensation reactions of alcohols on MgyAlOx catalysts
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A study of the effect of composition and of surface characteristics on alcohol-coupling reactions on MgyAlOx catalysts using C2H5OH or 13CH3OH/1-12C3H7OH mixtures as reactants showed that the biomolecular and consecutive character of the condensation reactions were affected by the catalyst acid-base properties and by the chemical nature of the alcohols and steric factors. The rates and product selectivity for C2H5OH or CH3OH/C3H7OH reactions strongly depended on the chemical composition of Mgy/AlOx samples. The chemical composition affected the acid-base properties of MgyAlOx samples. The rate of alcohol dehydration to ethers and olefins increased with increases in Al content. Al-rich MgyAlOx samples contained a high density of Al3+-O2- site pairs and of moderate strength basic sites, the combination of which promoted ethylene or propylene formation from primary alcohols via E2 elimination pathways. The competitive dehydration to form ethers involved the adsorption of two alcohol molecules on neighboring acid sites offering various acid-base properties. On MgyAlOx samples, the active acid sites for ether formation were possibly the Al3+ cations and the basic sites were the neighboring O2- ions. The dehydrogenation of alcohols to aldehydes involved the initial alkoxy intermediate formation on weak Lewis acid-strong Broensted base site pairs. The synthesis of C2H4O or C3H6O was favored on Mg-rich MgyAlOx samples, which contained a larger number of property positioned Al3+ Lewis acid sites and Mg2+-O2- basic pairs required for hydrogen abstraction steps leading to alkoxy intermediates. Pure MgO showed lower dehydrogenation rates than Mg-rich MgyAlOx samples. Aldol condensation reactions on MgyAlOx samples also involved the formation of a carbanion intermediate on Lewis acid-strong Broensted base pair sites and produced products with a novel C-C bond, e.g., n-C4H8O and iso-C4H8O. Reactions leading to condensation products were also favored on Mg-rich samples.
- Di Cosimo,Apesteguia,Gines,Iglesia
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- Production of Pure Aqueous13C-Hyperpolarized Acetate by Heterogeneous Parahydrogen-Induced Polarization
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A supported metal catalyst was designed, characterized, and tested for aqueous phase heterogeneous hydrogenation of vinyl acetate with parahydrogen to produce13C-hyperpolarized ethyl acetate for potential biomedical applications. The Rh/TiO2catalyst with a metal loading of 23.2 wt % produced strongly hyperpolarized13C-enriched ethyl acetate-1-13C detected at 9.4 T. An approximately 14-fold13C signal enhancement was detected using circa 50 % parahydrogen gas without taking into account relaxation losses before and after polarization transfer by magnetic field cycling from nascent parahydrogen-derived protons to13C nuclei. This first observation of13C PHIP-hyperpolarized products over a supported metal catalyst in an aqueous medium opens up new possibilities for production of catalyst-free aqueous solutions of nontoxic hyperpolarized contrast agents for a wide range of biomolecules amenable to the parahydrogen induced polarization by side arm hydrogenation (PHIP-SAH) approach.
- Kovtunov, Kirill V.,Barskiy, Danila A.,Shchepin, Roman V.,Salnikov, Oleg G.,Prosvirin, Igor P.,Bukhtiyarov, Andrey V.,Kovtunova, Larisa M.,Bukhtiyarov, Valerii I.,Koptyug, Igor V.,Chekmenev, Eduard Y.
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- Synthesis of methyl propanoate by Baeyer-Villiger monooxygenases
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Methyl propanoate is an important precursor for polymethyl methacrylates. The use of a Baeyer-Villiger monooxygenase (BVMO) to produce this compound was investigated. Several BVMOs were identified that produce the chemically non-preferred product methyl propanoate in addition to the normal product ethyl acetate. This journal is
- Van Beek, Hugo L.,Winter, Remko T.,Eastham, Graham R.,Fraaije, Marco W.
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- Low-Flammable Parahydrogen-Polarized MRI Contrast Agents
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Many MRI contrast agents formed with the parahydrogen-induced polarization (PHIP) technique exhibit biocompatible profiles. In the context of respiratory imaging with inhalable molecular contrast agents, the development of nonflammable contrast agents would nonetheless be highly beneficial for the biomedical translation of this sensitive, high-throughput and affordable hyperpolarization technique. To this end, we assess the hydrogenation kinetics, the polarization levels and the lifetimes of PHIP hyperpolarized products (acids, ethers and esters) at various degrees of fluorine substitution. The results highlight important trends as a function of molecular structure that are instrumental for the design of new, safe contrast agents for in vivo imaging applications of the PHIP technique, with an emphasis on the highly volatile group of ethers used as inhalable anesthetics.
- Ariyasingha, Nuwandi M.,Chekmenev, Eduard Y.,Chukanov, Nikita V.,Gelovani, Juri G.,Joalland, Baptiste,Koptyug, Igor V.,Kovtunov, Kirill V.,Nantogma, Shiraz,Salnikov, Oleg G.,Younes, Hassan R.
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- Synthesis of acetic acid from ethanol-water mixture over Cu/ZnO-ZrO 2-Al2O3 catalyst
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It was shown that acetic acid can be obtained from aqueous ethanol (6-40 mol%) solutions over Cu/ZnO-ZrO2-Al2O3 catalyst at 250-320 C and atmospheric pressure. Selectivity of 80-90% and space-time yield of acetic acid up to 9 mmol gcat-1 h-1 at 60-80% ethanol conversion were obtained while processing 14-37 mol% aqueous ethanol solutions. Hydrogen was generated in an amount ~2 moles per 1 mole of acetic acid as a co-product.
- Brei, Volodymyr V.,Sharanda, Mykhailo E.,Prudius, Svitlana V.,Bondarenko, Eugenia A.
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- Direct synthesis of ethyl acetate from ethanol carried out under pressure
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Direct synthesis of ethyl acetate from ethanol over a Cu-Zn-Zr-AI-O catalyst was studied under pressured conditions between 473 and 533 K. The selectivity to ethyl acetate and the space-time yield of ethyl acetate increased with increasing reaction pressure, whereas ethanol conversion decreased. The highest spacetime yield of ethyl acetate was achieved at a reaction pressure of about 0.8 MPa with maximum selectivity of 93 wt %. The products observed in the effluent include ethyl acetate, acetaldehyde, butanone, 1-butanol, and propanone. In the reaction of acetaldehyde in a flow of N2 hardly any converted to ethyl acetate and a small amount of acetaldol derivatives, e.g., 2-butenal and butanal, were observed. In contrast, the reaction of acetaldehyde in an H2 flow was accompanied by the formation of ethyl acetate as a major product and hydrogenated products, e.g., ethanol and 1-butanol. In the reaction of an equimolar mixture of acetaldehyde and ethanol in an N2 flow, the product distribution was also similar to that observed in the reaction of ethanol. Butanone was the major product of the 1,3-butanediol reaction.
- Inui, Kanichiro,Kurabayashi, Toru,Sato, Satoshi
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- Revised Mechanisms for Aldehyde Disproportionation and the Related Reactions of the Shvo Catalyst
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It is widely believed that the Shvo catalyst (1) dissociates to form two active species in solution: the 18-electron hydride RuH(CO)2[η5-C5(OH)Ph4] (2) and the naked 16-electron complex Ru(CO)2[η4-C5(=O)Ph4] (3). This combined experimental/computational study demonstrates that a sustained presence of 3 is not viable in the reactions of alcohols and organic carbonyls; thus, 3 is better treated as nonexistent under the typical catalytic conditions. We propose a modified view where the key catalytic species are the hydride 2 and the 18-electron metal alkoxide intermediate Ru(OR)(CO)2[η5-C5(OH)Ph4] existing in equilibrium with the corresponding alcohol complex. An X-ray crystallographic study of 2 revealed an interesting dihydrogen-bonded dimer structure in the solid state. The mechanistic ideas of this paper explain the highly efficient Tishchenko-like aldehyde disproportionation reaction with the Shvo catalyst. Additionally, our observations explain why 1 is inefficient for hydrogenation of ethyl acetate and for the acceptorless dehydrogenative coupling of ethanol. Our findings provide practical guidance for future catalyst design on the basis of the Shvo ruthenium dimer prototype.
- Gusev, Dmitry G.,Spasyuk, Denis M.
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- Gas-Phase Acylation Reactions. Substrate and Positional Selectivity of Free Acetylium Ions toward Methylbenzenes
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Free acetylium ions, obtained in the diluted gas state from the γ radiolysis of CH3F-CO mixtures, have been allowed to react with methylbenzenes, in the pressure range 380-760 Torr, and in the presence of a gaseous base (NH3).The gaseous cation has been confirmed to be unreactive toward benzene and toluene, whereas it acetylates the xylenes and the other selected polymethylated benzenes.The relative rates of acetylation have been determined in competition experiments, using mesitylene as the reference substrate.The mechanism of acetylation and subsequent isomerization is discussed, and the substrate and positional selectivity of the free CH3CO+ ion are evaluated, together with its intrinsic steric requirements.Comparison of the gas-phase results with those of related condensed-phase reactions, involving CH3CH+ salts as one of the reactive species, reveals no basic mechanistic differences.Some observed reactivity and selectivity discrepancies, in particular those concerning acetylation of toluene, o- and m-xylene, and hemimellitene, are outlined and their possible causes considered.
- Speranza, Maurizio,Sparapani, Cinzia
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- Deeper Mechanistic Insight into Ru Pincer-Mediated Acceptorless Dehydrogenative Coupling of Alcohols: Exchanges, Intermediates, and Deactivation Species
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The mechanism of acceptorless dehydrogenative coupling reaction (ADC) of alcohols to esters catalyzed by aliphatic pincer PHNP ruthenium complexes was experimentally studied. Relevant intermediate species involved in the catalytic cycle were isolated and structurally characterized by single-crystal X-ray diffraction studies, and their reactivity (including toward substrates related to the catalytic process) was probed. VT NMR studies unveiled several chemical exchanges connecting the Ru amido hydride, the Ru alkoxide, and the alcohol substrate. Under catalytic conditions, in situ IR spectroscopy monitoring demonstrated the production of ester via aldehyde as intermediate. A Tishchenko-like pathway is proposed as the main path for the production of ester from aldehyde, involving alkoxide and hemiacetaloxide Ru species (the latter being identified in the reaction mixture by NMR). Catalytic system deactivation under base-free conditions was found to be related to water traces in the reaction medium (either as impurity or derived from aldol reactions) that lead to the formation of catalytically inactive acetato Ru complexes. These react with alkali metal alkoxides to afford catalytically active Ru species. In line with this observation, running the ADC reaction in the presence of water scavengers or alkoxides allows maintaining sustained catalytic activity.
- Nguyen, Duc Hanh,Trivelli, Xavier,Capet, Frédéric,Swesi, Youssef,Favre-Réguillon, Alain,Vanoye, Laurent,Dumeignil, Franck,Gauvin, Régis M.
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- Copper-mediated decarboxylative coupling of benzamides with potassium malonate monoesters via directed CH cleavage
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A copper-mediated decarboxylative coupling of benzamides with potassium malonate monoesters via 8-aminoquinoline-directed CH cleavage has been developed. This reaction proceeds only by a copper salt to produce the corresponding alkylation products in good
- Takamatsu, Kazutaka,Hirano, Koji,Miura, Masahiro
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- Impact of the Oxygen Vacancies on Copper Electronic State and Activity of Cu-Based Catalysts in the Hydrogenation of Methyl Acetate to Ethanol
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Reducible oxides supported copper-based catalysts have been widely used in ester hydrogenations due to their excellent catalytic performance. However, the role of surface oxygen vacancies is still unclear. Here, we fabricated four copper-based catalysts u
- Xi, Yushan,Wang, Yue,Yao, Dawei,Li, Antai,Zhang, Jingyu,Zhao, Yujun,Lv, Jing,Ma, Xinbin
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- RADICAL TELOMERIZATION OF 3,3,3-TRIFLUOROPROPENE WITH 2-METHYL-1,3-DIOXOLANE
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The telomerization of 3,3,3-trifluoropropene with 2-methyl-1,3-dioxolane gives predominantly cyclic telomers as shown by 13C NMR and gas chromatography-mass spectrometry.This reaction is accompanied by the rearrangement of transient free radical intermediates via 1,5-H-migration. Keywords: radicals, addition, dioxolane, telomers, telomerization, kinetics.
- Terent'ev, A.B.,Pastushenko, E.V.,Kruglov, D.E.,Ryabinina, T.A.
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- FeSBA-15-supported ruthenium catalyst for the selective hydrogenolysis of carboxylic acids to alcoholic chemicals
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Ordered mesoporous FeSBA-15-supported Ru catalysts are characterized by N2 adsorption-desorption isotherm, H2-temperature-programmed reduction, X-ray fluorescence, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy analyses. Results suggest the co-existence of Fe oxide species highly dispersed in the frameworks of SBA-15 and Ru-Fe bimetallic nanoparticles. The concentration of Fe species is low and in the form of Ru-Fe alloys located on the catalyst surfaces following reduction pretreatment in 5% H2-95% N2 flow at 623 K for 4 h. The as-reduced Ru/FeSBA-15 catalysts efficiently and selectively hydrogenolyze short-chain carboxylic acids (e.g., acetic acid, propionic acid, butyric acid, levulinic acid, and lactic acid) to their corresponding alcoholic chemicals. Results indicate that 2% Ru/FeSBA-15 catalyst with 1.07% Fe content yields the highest performance and excellent stability, yielding 92.5% conversion of acetic acid and 85.2% selectivity to ethanol under optimized conditions. The improved catalytic performance of the FeSBA-15-supported Ru catalyst is mainly attributed to the coherent interactions between Fe and Ru species, as well as to the high dispersion of Fe oxides in the SBA-15 framework.
- Li, Wenjing,Ye, Linmin,Chen, Jin,Duan, Xinping,Lin, Haiqiang,Yuan, Youzhu
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- Effect of Support in Ethanol Oxidation on Molybdenum Oxide
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The oxidation of ethanol on MoO3 supported on SiO2, Al2O3, and TiO2 was studied in a flow reactor at atmospheric pressure.The reactivity sequence followed the order MoO3/TiO2 > MoO3/Al2O3 > MoO3/SiO2 and correlated with the reducibility of the surface molybdenum species.Ethanol oxidation produces mainly acetaldehyde, diethyl ehter, and ethylene through ethoxide type intermediates adsorbed on different sites (M=O, Mo-O-Mo, or Mo-O-M).Two types of ethoxide species were identified using laser Raman spectroscopy under in situ conditions and could be associated with the Mo=O and Mo-O-Mo sites.Although rates were strongly affected by the support, suggesting that activity was controlled by a term in the preexponential factor.The link to reducibility and the existence of a common ethoxide intermediate indicated that the controlling factor was likely to be the electronic partition function associated with the density of electron-accepting levels in the molybdate-support complex.
- Zhang, Weimin,Desikan Anantha,Oyama, S. Ted
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- Bifunctional mesoporous organic-inorganic hybrid silica for combined one-step hydrogenation/esterification
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Bifunctional mesoporous organic-inorganic hybrid silicas with platinum and propylsulfonic acid group (Pt/SBA15-PrSO3H) were synthesized and tested for the combined one-step hydrogenation/esterification (OHE) reaction, which was employed as a model reaction for catalytic upgrading of biomass-derived bio-oil. The model reagents used were acetic acid and acetaldehyde. Different catalyst synthesis procedures were investigated and compared by varying the functional group incorporation method, platinum loading, reducing agent, etc. The textural and chemical properties of the catalysts made by the different synthesis procedures were characterized and compared with reactivity results. The need to create the organic acid sites prior to platinum incorporation was demonstrated. The efficacy of the bifunctional catalyst system for combined hydrogenation/esterification was demonstrated. Interestingly, the bifunctional Pt/SBA15-PrSO3H catalyst exhibited superior esterification activity with about twice the acetic acid turnover number relative to that with the monofunctional SBA15-PrSO3H catalyst. By combining metallic Pt nanoparticles with strong acid sites, this bifunctional mesoporous hybrid catalyst improved OHE activity and, therefore, has potential for application in the catalytic upgrading of bio-oil.
- Tang, Yang,Miao, Shaojun,Shanks, Brent H.,Zheng, Xiaoming
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- Facile synthesis of homogeneous CsxWO3 nanorods with excellent low-emissivity and NIR shielding property by a water controlled-release process
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A systematic investigation of the synthesis of homogenous Cs xWO3 nanorods by a designed water-controlled release process was carried out. The results revealed that the uniform rod-like Cs xWO3 nanoparticles with a Cs/W atomic ratio of ca. 0.33 can be obtained by using 20 vol% CH3COOH-80 vol% CH 3CH2OH mixed solution as a reaction solvent at 240°C for 20 h. The morphology of products were changed depending on the speed of water-releasing process, meanwhile, the Cs/W atomic ratio could be controlled by both the amount of released water and the reaction temperature. Cs xWO3 nanorods showed a high transmittance in the visible light region and excellent shielding ability of near infrared (NIR) lights, indicating that CsxWO3 nanorods have a suitable characteristic as solar filter applications. The Royal Society of Chemistry 2011.
- Guo, Chongshen,Yin, Shu,Yan, Mei,Sato, Tsugio
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- Highly selective 1-butanol obtained from ethanol catalyzed by mixed metal oxides: Reaction optimization and catalyst structure behavior
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Synthesis and characterization of a copper mixed metal oxide obtained from hydrotalcite precursor as well as catalytic runs for ethanol conversion to 1-butanol are described. Applying the surface response model, the reaction was optimized reaching an ethanol conversion of 79.6% into gaseous phase (69% of yield) and condensed phase (31% of yield) products using a batch reactor at 350 °C for 5 h. The main product of the condensed phase was 1-butanol with 25.4% yield and 32% selectivity, these results being among the higher ones reported for this reaction in the literature. Recycling catalyst experiments demonstrated that, for at least four cycles, the ethanol conversion remains almost constant but the 1-butanol yield and selectivity both decreased. XRD, EPR, surface area measurements and acidity/basicity experiments carried out after the first and fourth catalyst recycling cycles show major modifications in the initial mixed metal oxide structure and copper oxidation state indicating that the active catalytic species increases during the first catalytic run.
- Rechi Siqueira, Marcos,Micali Perrone,Metzker, Gustavo,de Oliveira Lisboa, Daniela Correa,Thoméo, Jo?o Cláudio,Boscolo, Maurício
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- Structural investigation of solid-acid-promoted Pd/SDB catalysts for ethyl acetate production from ethanol
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Catalyzed by styrene-divinylbenzene copolymer (SDB)-supported Pd (Pd/SDB) catalysts, ethyl acetate can be formed from water-containing ethanol via concomitant partial oxidation and esterification reaction. The partial oxidation reaction is carried out ove
- Lee,Zheng,Chang
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- Thermal decomposition of acetyl propionyl peroxide in acetone-d6
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The kinetics of thermolysis of acetyl propinyl peroxide in acetone-d 6 in the temperature range 323-373 K was studied using NMR spectroscopy and the effect of chemically induced nuclear polarization. The peroxide decomposes in acetone at rates comparable with the rates of thermolysis in alcohols, yielding numerous products. In the examined temperature range, the solvent molecules act as efficient donors of deuterium atoms, forming acetylmethyl-d5 radicals which recombine to a significant extent with the peroxide radicals. A scheme of the processes involved in decomposition of the peroxide was suggested. The parameters of the Arrhenius equation for the peroxide decomposition were determined. 2004 MAIK "Nauka/ Interperiodica".
- Skakovskii,Stankevich,Tychinskaya,Shirokii,Choban,Murashko,Rykov
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- Facile Preparation of Methyl Phenols from Ethanol over Lamellar Ce(OH)SO4· xH2O
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Ethanol transformation with high product selectivity is a great challenge, especially for high weight molecules. Here, we show a combination study of kinetic, thermodynamic, and in situ spectroscopy measurements to probe the selective upgrading of ethanol over lamellar Ce(OH)SO4·xH2O catalysts, with 60-70% Ce3+ preserved during the catalysis. High methyl phenols (MPs) selectivity at ～80% within condensation products was achieved at ～50% condensation yield (3.0 kPa C2H5OH, 15 kPa H2, Ar balanced, 693 K, 1 atm, gas hourly space velocity (GHSV) ～5.4 min-1), with acetaldehyde, acetone, 4-heptanone, and 2-pentanone as the key reaction intermediates. Kinetic measurements with the assistance of isotope labeling proved that MPs generated from the kinetically relevant step (KRS) of C-C bond coupling of enolate nucleophilically attacks surface C2H4O following a Langmuir-Hinshelwood model. Low ethanol and water pressures and high acetaldehyde and hydrogen pressures were proved to be favored for MPs generation rather than dehydration, in which hydrogen could reduce the amount of lattice oxygen and facilitate the preparation of MPs while water and ethanol both compete with acetaldehyde for active sites during catalysis. On the basis of in situ X-ray diffraction (XRD), quasi-in situ X-ray photoelectron spectroscopy (XPS), and Raman characterizations, the Ce(OH)SO4 crystal structure was proved to be maintained along with ethanol activation, and the Ce3+-OH Lewis acid-base pair was proved to be the active species for the selective C-C bond coupling. The KRS assumption was also supported by the apparent activation energy assessment within the reaction network on dehydration, dehydrogenation, aldol condensation, and cyclization and a series of negligible kinetic isotope effects (KIEs). This system can be easily extended to some other systems related to C-C bond coupling and is attracting attention on converting oxygenate platform molecules over lanthanide species.
- Guo, Jinqiu,Feng, Zongjing,Xu, Jun,Zhu, Jie,Zhang, Guanghui,Du, Yaping,Zhang, Hongbo,Yan, Chunhua
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- The Reaction of with Triethoxysilane in the Presence of PPh3: a New Method for Synthesis of
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The reaction of with triethoxysilane in the presence of PPh3 is examined under oxygen-free conditions, permitting isolation of 1 formed by elimination of one acac ligand (as protonated and hydrosilylated product) from the nickel complex with its simultaneous silylation which is followed by C-O bond cleavage in triethoxysilyl ligand via a mechanism involving transfer of an ethyl group to Ni with elimination of pentaethoxyhydrodisiloxane in the excess of triethoxysilane.
- Marciniec, Bogdan,Maciejewski, Hieronim,Gulinski, Jacek
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- Removal of the copper catalyst from atom transfer radical polymerization mixtures by chemical reduction with zinc powder
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Simple mixing of an atom transfer radical polymerization (ATRP) mixture with zinc powder was demonstrated to result in rapid decolorizing of the solution and precipitation of elemental copper, using small amounts of silica gel as seeding material. The experiments revealed that the chemical reduction of copper by wetted zinc powder (i.e., 0.325 g/mmol copper) is fast and completed within less than 5 min. UV spectra of the filtered polymer solution showed no any trace of copper. Terminal bromoalkyl groups of the polymers in the ATRP solution were determined to be unchanged by short-term contact with zinc powder at room temperature and a nearly complete reductive dehalogenation takes place only after 24 h of interaction, as evidenced by reaction of elemental zinc with a model compound, ethyl bromoacetate. Indeed, poly(methyl methacrylate) (PMMA) sample (Mn: 7900, polydispersity index: 1.09) isolated from ATRP mixture after the copper removal a by short contact with zinc powder (i.e., 15 min) was determined "still living" as confirmed by chain extension with styrene, ethyl acrylate, and t-butyl acrylate monomers to give block copolymers. The presence of acetic acid was demonstrated to accelerate reductive dehalogenation of PMMA end-groups by zinc and yields nonliving polymer within 2 h.
- Canturk, Fatma,Karagoz, Bunyamin,Bicak, Niyazi
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- DEUTERIUM ISOTOPE EFFECTS IN THE THERMAL DECOMPOSITION OF β-HYDROXY KETONES AND β-HYDROXY ESTERS
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Small primary and cumulative secondary isotope effects are determined experimentally by thermolysis of various β-hydroxy ketones and β-hydroxy esters.
- Quijano, J.,Rodriguez, M. M.,Yepes, M. del S.,Gallego, L.H.
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- Insight into the balancing effect of active Cu species for hydrogenation of carbon-oxygen bonds
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Hydrogenation of carbon-oxygen (C-O) bonds plays a significant role in organic synthesis. Cu-based catalysts have been extensively investigated because of their high selectivity in C-O hydrogenation. However, no consensus has been reached on the precise roles of Cu0 and Cu+ species for C-O hydrogenation reactions. Here we resolve this long-term dispute with a series of highly comparable Cu/SiO2 catalysts. All catalysts represent the full-range distribution of the Cu species and have similar general morphologies, which are detected and mutually corroborated by multiple characterizations. The results demonstrate that, when the accessible metallic Cu surface area is below a certain value, the catalytic activity of hydrogenation linearly increases with increasing Cu0 surface area, whereas it is primarily affected by the Cu+ surface area. Furthermore, the balancing effect of these two active Cu sites on enhancing the catalytic performance is demonstrated: the Cu+ sites adsorb the methoxy and acyl species, while the Cu0 facilitates the H2 decomposition. This insight into the precise roles of active species can lead to new possibilities in the rational design of catalysts for hydrogenation of C-O bonds.
- Wang, Yue,Shen, Yongli,Zhao, Yujun,Lv, Jing,Wang, Shengping,Ma, Xinbin
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- Dehydrogenative ester synthesis from enol ethers and water with a ruthenium complex catalyzing two reactions in synergy
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We report the dehydrogenative synthesis of esters from enol ethers using water as the formal oxidant, catalyzed by a newly developed ruthenium acridine-based PNP(Ph)-type complex. Mechanistic experiments and density functional theory (DFT) studies suggest that an inner-sphere stepwise coupled reaction pathway is operational instead of a more intuitive outer-sphere tandem hydration-dehydrogenation pathway.
- Ben-David, Yehoshoa,Diskin-Posner, Yael,Kar, Sayan,Luo, Jie,Milstein, David,Rauch, Michael
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supporting information
p. 1481 - 1487
(2022/03/07)
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- Dual utility of a single diphosphine-ruthenium complex: A precursor for new complexes and, a pre-catalyst for transfer-hydrogenation and Oppenauer oxidation
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The diphosphine-ruthenium complex, [Ru(dppbz)(CO)2Cl2] (dppbz = 1,2-bis(diphenylphosphino)benzene), where the two carbonyls are mutually cis and the two chlorides are trans, has been found to serve as an efficient precursor for the synthesis of new complexes. In [Ru(dppbz)(CO)2Cl2] one of the two carbonyls undergoes facile displacement by neutral monodentate ligands (L) to afford complexes of the type [Ru(dppbz)(CO)(L)Cl2] (L = acetonitrile, 4-picoline and dimethyl sulfoxide). Both the carbonyls in [Ru(dppbz)(CO)2Cl2] are displaced on reaction with another equivalent of dppbz to afford [Ru(dppbz)2Cl2]. The two carbonyls and the two chlorides in [Ru(dppbz)(CO)2Cl2] could be displaced together by chelating mono-anionic bidentate ligands, viz. anions derived from 8-hydroxyquinoline (Hq) and 2-picolinic acid (Hpic) via loss of a proton, to afford the mixed-tris complexes [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], respectively. The molecular structures of four selected complexes, viz. [Ru(dppbz)(CO)(dmso)Cl2], [Ru(dppbz)2Cl2], [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], have been determined by X-ray crystallography. In dichloromethane solution, all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows redox responses within 0.71 to -1.24 V vs. SCE. [Ru(dppbz)(CO)2Cl2] has been found to serve as an excellent pre-catalyst for catalytic transfer-hydrogenation and Oppenauer oxidation.
- Mukherjee, Aparajita,Bhattacharya, Samaresh
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p. 15617 - 15631
(2021/05/19)
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- Design, Synthesis, and Study of the Insecticidal Activity of Novel Steroidal 1,3,4-Oxadiazoles
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A series of novel steroidal derivatives with a substituted 1,3,4-oxadiazole structure was designed and synthesized, and the target compounds were evaluated for their insecticidal activity against five aphid species. Most of the tested compounds exhibited potent insecticidal activity against Eriosoma lanigerum (Hausmann), Myzus persicae, and Aphis citricola. Compounds 20g and 24g displayed the highest activity against E. lanigerum, showing LC50 values of 27.6 and 30.4 μg/mL, respectively. Ultrastructural changes in the midgut cells of E. lanigerum were detected by transmission electron microscopy, indicating that these steroidal oxazole derivatives might exert their insecticidal activity by destroying the mitochondria and nuclear membranes in insect midgut cells. Furthermore, a field trial showed that compound 20g exhibited effects similar to those of the positive controls chlorpyrifos and thiamethoxam against E. lanigerum, reaching a control rate of 89.5% at a dose of 200 μg/mL after 21 days. We also investigated the hydrolysis and metabolism of the target compounds in E. lanigerum by assaying the activities of three insecticide-detoxifying enzymes. Compound 20g at 50 μg/mL exhibited inhibitory action on carboxylesterase similar to the known inhibitor triphenyl phosphate. The above results demonstrate the potential of these steroidal oxazole derivatives to be developed as novel pesticides.
- Bai, Hangyu,Jiang, Weiqi,Li, Qi,Li, Tian,Ma, Shichuang,Shi, Baojun,Wu, Wenjun
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p. 11572 - 11581
(2021/10/12)
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- Chemoselective Hydrogenation of Olefins Using a Nanostructured Nickel Catalyst
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The selective hydrogenation of functionalized olefins is of great importance in the chemical and pharmaceutical industry. Here, we report on a nanostructured nickel catalyst that enables the selective hydrogenation of purely aliphatic and functionalized olefins under mild conditions. The earth-abundant metal catalyst allows the selective hydrogenation of sterically protected olefins and further tolerates functional groups such as carbonyls, esters, ethers and nitriles. The characterization of our catalyst revealed the formation of surface oxidized metallic nickel nanoparticles stabilized by a N-doped carbon layer on the active carbon support.
- Klarner, Mara,Bieger, Sandra,Drechsler, Markus,Kempe, Rhett
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supporting information
p. 2157 - 2161
(2021/05/21)
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- Background-Free Proton NMR Spectroscopy with Radiofrequency Amplification by Stimulated Emission Radiation
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We report on the utility of Radiofrequency Amplification by Stimulated Emission Radiation (RASER) for background-free proton detection of hyperpolarized biomolecules. We performed hyperpolarization of ≈0.3 M ethyl acetate via pairwise parahydrogen addition to vinyl acetate. A proton NMR signal with signal-to-noise ratio exceeding 100 000 was detected without radio-frequency excitation at the clinically relevant magnetic field of 1.4 T using a standard (non-cryogenic) inductive detector with quality factor of Q=68. No proton background signal was observed from protonated solvent (methanol) or other added co-solvents such as ethanol, water or bovine serum. Moreover, we demonstrate RASER detection without radio-frequency excitation of a bolus of hyperpolarized contrast agent in biological fluid. Completely background-free proton detection of hyperpolarized contrast agents in biological media paves the way to new applications in the areas of high-resolution NMR spectroscopy and in vivo spectroscopy and imaging.
- Appelt, Stephan,Chekmenev, Eduard Y.,Joalland, Baptiste,Theis, Thomas
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p. 26298 - 26302
(2021/10/04)
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- Interfacial Sites in Ag Supported Layered Double Oxide for Dehydrogenation Coupling of Ethanol to n-Butanol
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Upgrading of ethanol to n-butanol through dehydrogenation coupling has received increasing attention due to the wide application of n-butanol. But the enhancement of ethanol dehydrogenation and followed coupling to produce high selectivity to n-butanol is still highly desired. Our previous work has reported an acid-base-Ag synergistic catalysis, with Ag particles supported on Mg and Al-containing layered double oxides (Ag/MgAl-LDO). Here, Ag-LDO interfaces have been manipulated for dehydrogenation coupling of ethanol to n-butanol by tailoring the size of Ag particles and the interactions between Ag and LDO. It has been revealed that increasing the population of surface Ag sites at Ag-LDO interfaces promotes not only the dehydrogenation of ethanol to acetaldehyde but also the subsequent aldol condensation of generated acetaldehyde. A selectivity of up to 76 % to n-butanol with an ethanol conversion of 44 % has been achieved on Ag/LDO with abundant interfacial Ag sites, much superior to the state-of-the-art catalysts.
- Zhang, Jian,Shi, Kai,Zhu, Yanru,An, Zhe,Wang, Wanning,Ma, Xiaodan,Shu, Xin,Song, Hongyan,Xiang, Xu,He, Jing
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p. 1095 - 1103
(2021/02/01)
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- First row transition metals on the ethanol Guerbet reaction: Products distribution and structural behavior of mixed metal oxides as catalysts
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Described is the transformation of ethanol into 1-butanol, acetaldehyde and other products by the Guerbet reaction (GR) over mixed metal oxides (MMOs) as catalysts. The MMOs, in which Mg2+ was partially (20 mol%) substituted by Fe2+, Co2+, Ni2+, Cu2+, and Zn2+, were obtained from hydrotalcite precursors and the reactions conducted in a fixed bed flow reactor. EPR was used to observe oxygen vacancies after the catalytic reactions, which may be related to the ethanol reactivity due to the basicity enhancement of the catalyst. Carbon deposition, mostly filamentous, was observed in all catalysts and a trend between the metal-carbon bond energy and the percentage of deposited carbon was established. This correlation and the catalyst product distribution can be useful to tailor new catalysts. Using four parameters, ethanol conversion, 1-butanol and side-product selectivities and percentage of carbon deposition, Zn20MMO proved to be the best choice for GR.
- Boscolo, Mauricio,Metzker, Gustavo,Mora Vargas, Jorge Andres,Perrone, Olavo Micali,Siqueira, Marcos Rechi,Varanda, Laudemir Carlos,de Lima, Livia Padilha
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- Catalytic Hydrogenation of Trivinyl Orthoacetate: Mechanisms Elucidated by Parahydrogen Induced Polarization
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Parahydrogen (pH2) induced polarization (PHIP) is a unique method that is used in analytical chemistry to elucidate catalytic hydrogenation pathways and to increase the signal of small metabolites in MRI and NMR. PHIP is based on adding or exchanging at least one pH2 molecule with a target molecule. Thus, the spin order available for hyperpolarization is often limited to that of one pH2 molecule. To break this limit, we investigated the addition of multiple pH2 molecules to one precursor. We studied the feasibility of the simultaneous hydrogenation of three arms of trivinyl orthoacetate (TVOA) intending to obtain hyperpolarized acetate. It was found that semihydrogenated TVOA underwent a fast decomposition accompanied by several minor reactions including an exchange of geminal methylene protons of a vinyl ester with pH2. The study shows that multiple vinyl ester groups are not suitable for a fast and clean (without any side products) hydrogenation and hyperpolarization that is desired in biochemical applications.
- Pravdivtsev, Andrey N.,Brahms, Arne,Kienitz, Stephan,S?nnichsen, Frank D.,H?vener, Jan-Bernd,Herges, Rainer
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p. 370 - 377
(2021/02/09)
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- Alcohol-Activated Vanadium-Containing Polyoxometalate Complexes in Homogeneous Glucose Oxidation Identified with 51V-NMR and EPR Spectroscopy
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Alcoholic solvents, especially methanol, show an activating affect for heteropolyacids in homogenously catalysed glucose transformation reactions. In detail, they manipulate the polyoxometalate-based catalyst in a way that thermodynamically favoured total oxidation to CO2 can be completely supressed. This allows a nearly 100 % carbon efficiency in the transformation reaction of glucose to methyl formate in methanolic solution at mild reaction conditions of 90 °C and 20 bar oxygen pressure. By using powerful spectroscopic tools like 51V-NMR and continuous wave EPR we could unambiguously prove that the vanadate-methanol-complex[VO(OMe)3]n is responsible for the selectivity shift in methanolic solution compared to the aqueous reference system.
- Wesinger, Stefanie,Mendt, Matthias,Albert, Jakob
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p. 3662 - 3670
(2021/06/18)
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- Synthesis of cyclohexanol and ethanol via the hydrogenation of cyclohexyl acetate with Cu2Znx/Al2O3catalysts
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Cyclohexanol (CHOL), as a value-added chemical, has attracted much attention due to its huge application market. The hydrogenation of cyclohexyl acetate (CHA), derived from the esterification of acetic acid and cyclohexene, not only provides a novel route to yield CHOL and ethanol (EtOH), but also rationally utilizes excess acetic acid. In this work, a series of Zn-promoted Cu/Al2O3 catalysts were prepared via a deposition-precipitation method for the liquid-phase hydrogenation of CHA to yield CHOL and EtOH. As a result, the addition of Zn species with an optimal amount greatly improved the activity and selectivity to CHOL and EtOH. A Cu2Zn1.25/Al2O3 catalyst, which contained 16.2 wt% Cu and 9.6 wt% Zn, exhibited superior catalytic performance with 93.9% conversion of CHA and 97.2% selectivity to EtOH along with 97.1% selectivity to CHOL in a batch reactor. The Cu2Zn1.25/Al2O3 catalyst also showed excellent stability and there was no deactivation after five runs. Based on detailed characterization, it was revealed that the addition of Zn species increased the dispersion of Cu particles, adjusted the strength and amount of acid sites, and changed the electronic properties of Cu species and thus the ratio of Cu+/(Cu0 + Cu+).
- Li, Kefan,Li, Xiaohong,Qi, Yuanyuan,Song, Tongyang,Wu, Peng,Zhu, Zhirong
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p. 7035 - 7046
(2021/11/16)
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- Predicting a Sharp Decline in Selectivity for Catalytic Esterification of Alcohols from van der Waals Interactions
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Controlling the selectivity of catalytic reactions is a critical aspect of improving energy efficiency in the chemical industry; thus, predictive models are of key importance. Herein the performance of a heterogeneous, nanoporous Au catalyst is predicted for the complex catalytic self-coupling of the series of C2–C4 alkyl alcohols, based solely on the known kinetics of the elementary steps of the catalytic cycle for methanol coupling, using scaling methods augmented by density functional theory. Notably, a sharp decrease in selectivity for ester formation with increasing molecular weight to favor the aldehyde due to van der Waals interactions of reaction intermediates with the surface was predicted and subsequently verified quantitatively by experiment. Further, the agreement between theory and experiment clearly demonstrates the efficacy of this approach for building a predictive model of catalytic behavior for a homologous set of reactants using a small set of experimental information.
- Friend, Cynthia M.,Luneau, Mathilde,Madix, Robert J.,Reece, Christian
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supporting information
p. 10864 - 10867
(2020/05/08)
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- A study of ethanol dehydrogenation to acetaldehyde over copper/zinc aluminate catalysts
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Catalysts composed of copper supported on ZnAl2O4 were prepared by conventional impregnation of a commercial zinc aluminate powder using copper nitrate water solutions. The fresh catalysts were characterized by XRD, skeletal IR and DR-UV–vis spectroscopies, FE-SEM microscopy, BET and pore volume measurements. The catalysts were tested in the conversion of ethanol (96percent assay, 6.9percent vol in nitrogen) at GHSV 10,000 h?1. The spent catalysts were characterized by FESEM and DR-UV–vis. These catalysts are very efficient for the dehydrogenation of ethanol to acetaldehyde, with selectivities in excess of 95percent at low conversion, persisting also at total conversion, allowing yields up to 90percent. The most active species appear to be on copper metal nanoparticles grown over Zn-poor substoichiometric spinel nanoparticles. The catalysts reduce themselves on stream. The high selectivity at low temperature is in part due to the ability of copper to kill the dehydration activity of the zinc aluminate support to diethyl ether. The selectivity to acetaldehyde decreases at very high temperature (> 673 K) due to overconversion of acetaldehyde to thermodynamically more stable products such as methane, acetone, propene and carbon oxides, as well as to increased competition with the more favored dehydration reaction. IR studies show the intermediate role of surface ethoxy-groups.
- Garbarino, Gabriella,Riani, Paola,Villa García, María,Finocchio, Elisabetta,Sanchez Escribano, Vicente,Busca, Guido
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p. 167 - 175
(2019/02/05)
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- Parahydrogen-Induced Radio Amplification by Stimulated Emission of Radiation
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Radio amplification by stimulated emission of radiation (RASER) was recently discovered in a low-field NMR spectrometer incorporating a highly specialized radio-frequency resonator, where a high degree of proton-spin polarization was achieved by reversible parahydrogen exchange. RASER activity, which results from the coherent coupling between the nuclear spins and the inductive detector, can overcome the limits of frequency resolution in NMR. Here we show that this phenomenon is not limited to low magnetic fields or the use of resonators with high-quality factors. We use a commercial bench-top 1.4 T NMR spectrometer in conjunction with pairwise parahydrogen addition producing proton-hyperpolarized molecules in the Earth's magnetic field (ALTADENA condition) or in a high magnetic field (PASADENA condition) to induce RASER without any radio-frequency excitation pulses. The results demonstrate that RASER activity can be observed on virtually any NMR spectrometer and measures most of the important NMR parameters with high precision.
- Joalland, Baptiste,Ariyasingha, Nuwandi M.,Lehmkuhl, S?ren,Theis, Thomas,Appelt, Stephan,Chekmenev, Eduard Y.
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supporting information
p. 8654 - 8660
(2020/03/30)
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- Revised Mechanisms of the Catalytic Alcohol Dehydrogenation and Ester Reduction with the Milstein PNN Complex of Ruthenium
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The combined experimental/DFT computational study of RuH2(CO)[Et2NCH2PyCH2Pt-Bu2] (2) suggests that this dihydride is the catalyst of the acceptorless alcohol dehydrogenation and ester hydrogenation reactions developed in the group of Milstein, whereas the corresponding alkoxide RuH(OR)(CO)[Et2NCH2PyCH2Pt-Bu2] (4) is an important reaction intermediate. A relatively fast equilibrium of dihydride 2 and ethanol with ethoxide 4 and H2 was demonstrated by NMR experiments, as well as the proton exchanges occurring between the OH of ethanol, RuH, and the CH2 groups of the PNN ligand backbone of 2 and 4. A detailed critical discussion of the previously proposed mechanisms with the Milstein catalyst is presented. This paper also reports the preparation of the osmium dihydride OsH2(CO)[Et2NCH2PyCH2Pt-Bu2] (2-Os) and a comparative study of 2, 2-Os, and the Noyori-type osmium catalyst OsH2(CO)[PyCH2NHCH2CH2NHPt-Bu2].
- Gusev, Dmitry G.
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- Elucidating structure-performance correlations in gas-phase selective ethanol oxidation and CO oxidation over metal-doped γ-MnO2
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Despite of considerable efforts on the MnO2-based catalytic combustion, the different structural and component requirements of MnO2 for gas-phase selective oxidation and complete oxidation largely remain unknown. By comparing four types of MnO2 with different crystal structures (α, β, γ and δ), γ-MnO2 was found to be the most efficient catalyst for both aerobic selective oxidation of ethanol and CO oxidation. The structural effect of γ-MnO2 was further investigated by doping metal ions into the framework and by comparing the catalytic performance in the gas-phase aerobic oxidation of CO and ethanol. Among ten M-γ-MnO2 catalysts, Zn-γ-MnO2 showed the lowest temperature (160 °C) for achieving 90% CO conversion. The CO oxidation activity of the M-γ-MnO2 catalysts was found to be more relevant to the surface acidity-basicity than the reducibility. In contrast, surface reducibility has been demonstrated to be more crucial in the gas-phase ethanol oxidation. Cu-γ-MnO2 with higher reducibility and more oxygen vacancies of Mn2+/Mn3+ species exhibited higher catalytic activity in the selective ethanol oxidation. Cu-γ-MnO2 achieved the highest acetaldehyde yield (75%) and space-time-yield (5.4 g gcat–1 h–1) at 200 °C, which are even comparable to the results obtained by the state-of-the-art silver and gold-containing catalysts. Characterization results and kinetic studies further suggest that the CO oxidation follows the lattice oxygen-based Mars-van Krevelen mechanism, whereas both surface lattice oxygen and adsorbed oxygen species involve in the ethanol activation.
- Wang, Panpan,Duan, Jiahao,Wang, Jie,Mei, Fuming,Liu, Peng
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p. 1298 - 1310
(2020/03/13)
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- Metal complex catalysts and method for catalytically reducing carboxylic acids
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The invention relates to a metal complex catalyst, which contains at least one of metal complexes with a chemical formula comprising a structural unit represented by a formula I. According to the invention, the center metal of the metal complex catalyst is iridium, and the metal complex catalyst is composed of pentamethylcyclopentadienyl, a bitetrahydropyrimidine ligand and proper coordination anions; the metal complex catalyst has activity on a carboxylic acid reduction reaction, and a carboxylic acid compound is reduced into an alcohol compound in the presence of hydrogen; and the method ismild in reaction condition, can be carried out at room temperature, and is good in catalytic performance and high in reduction product yield.
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Paragraph 0085-0144; 0167; 0168; 0172-0179
(2020/06/20)
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- Self-Exfoliated Synthesis of Transition Metal Phosphate Nanolayers for Selective Aerobic Oxidation of Ethyl Lactate to Ethyl Pyruvate
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Two-dimensional (2D) transition metal nanosheets are promising catalysts because of the enhanced exposure of the active species compared to their 3D counterparts. Here, we report a simple, scalable, and reproducible strategy to prepare 2D phosphate nanosheets by forming a layered structure in situ from phytic acid (PTA) and transition metal precursors. Controlled combustion of the organic groups of PTA results in interlayer carbon, which keeps the layers apart during the formation of phosphate, and the removal of this carbon results in ultrathin nanosheets with controllable layers. Applying this concept to vanadyl phosphate synthesis, we show that the method yields 2D ultrathin nanosheets of the orthorhombic β-form, exposing abundant V4+/V5+ redox sites and oxygen vacancies. We demonstrate the high catalytic activity of this material in the vapor-phase aerobic oxidation of ethyl lactate to ethyl pyruvate. Importantly, these β-VOPO4 compounds do not get hydrated, thereby reducing the competing hydrolysis reaction by water byproducts. The result has superior selectivity to ethyl pyruvate compared to analogous vanadyl phosphates. The catalysts are highly stable, maintaining a steady-state conversion of ～90% (with >80% selectivity) for at least 80 h on stream. This "self-exfoliated" synthesis protocol opens opportunities for preparing structurally diverse metal phosphates for catalysis and other applications.
- Li, Lain-Jong,Oulego, Paula,Rothenberg, Gadi,Sharma, Sandeep K.,Shiju, N. Raveendran,Yang, Xiu-Lin,Zhang, Wei
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p. 3958 - 3967
(2020/05/05)
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- Synthesis of α,β- and β-Unsaturated Acids and Hydroxy Acids by Tandem Oxidation, Epoxidation, and Hydrolysis/Hydrogenation of Bioethanol Derivatives
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We report a reaction platform for the synthesis of three different high-value specialty chemical building blocks starting from bio-ethanol, which might have an important impact in the implementation of biorefineries. First, oxidative dehydrogenation of ethanol to acetaldehyde generates an aldehyde-containing stream active for the production of C4 aldehydes via base-catalyzed aldol-condensation. Then, the resulting C4 adduct is selectively converted into crotonic acid via catalytic aerobic oxidation (62 % yield). Using a sequential epoxidation and hydrogenation of crotonic acid leads to 29 % yield of β-hydroxy acid (3-hydroxybutanoic acid). By controlling the pH of the reaction media, it is possible to hydrolyze the oxirane moiety leading to 21 % yield of α,β-dihydroxy acid (2,3-dihydroxybutanoic acid). Crotonic acid, 3-hydroxybutanoic acid, and 2,3-dihydroxybutanoic acid are archetypal specialty chemicals used in the synthesis of polyvinyl-co-unsaturated acids resins, pharmaceutics, and bio-degradable/ -compatible polymers, respectively.
- Faria, Jimmy,Komarneni, Mallik R.,Li, Gengnan,Pham, Tu,Resasco, Daniel E.,Ruiz, Maria P.,Santhanaraj, Daniel
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supporting information
p. 7456 - 7460
(2020/03/23)
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- METHOD FOR DIRECTLY PRODUCING ETHANOL FROM SYNGAS
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A method for directly producing ethanol from syngas, carried out in three reaction zones, including: feeding a raw material containing syngas and dimethyl ether into a first reaction zone to contact with a solid acid catalyst, reacting; allowing the effluent from the first reaction zone to enter a second reaction zone to contact with a metal catalyst and react; separating the effluent from the second reaction zone to obtain product ethanol and by-product methanol; allowing by-product methanol to enter a third reaction zone to perform a dehydration reaction to obtain dimethyl ether, and allowing the obtained dimethyl ether to enter the first reaction zone to recycle the reaction. This provides a novel method for directly converting syngas to ethanol and an ethanol product can be directly produced by using syngas as a raw material.
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Paragraph 0053-0056; 0060
(2020/08/05)
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- Catalytic upgrading of ethanol to butanol over a binary catalytic system of FeNiOx and LiOH
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Catalytic conversion of ethanol to butanol is vital to bridge the gap between huge amounts of ethanol production, the limited blending ratio of ethanol in gasoline, and the outstanding performance of butanol. In this work, a highly active binary catalytic system of FeNiOx and LiOH was developed for upgrading of ethanol to butanol. After 24 h reaction at 493 K, the selectivity to butanol reached 71% with >90% high carbon alcohols at 28% ethanol conversion, which was comparable to the performance of some noble metal homogeneous catalysts.
- Li, Xianquan,Li, Xinsheng,Liu, Shimin,Pang, Jifeng,Wang, Junhu,Wang, Zhinuo,Zhang, Tao,Zheng, Mingyuan
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p. 672 - 678
(2020/01/28)
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- A Reversible Liquid-to-Liquid Organic Hydrogen Carrier System Based on Ethylene Glycol and Ethanol
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Liquid organic hydrogen carriers (LOHCs) are powerful systems for the efficient unloading and loading molecular hydrogen. Herein, a liquid-to-liquid organic hydrogen carrier system based on reversible dehydrogenative coupling of ethylene glycol (EG) with ethanol catalysed by ruthenium pincer complexes is reported. Noticeable advantages of the current LOHC system is that both reactants (hydrogen-rich components) and the produced esters (hydrogen-lean components) are liquids at room temperature, and the dehydrogenation process can be performed under solvent and base-free conditions. Moreover, the hydrogenation reaction proceeds under low hydrogen pressure (5 bar), and the LOHC system has a relatively high theoretical gravimetric hydrogen storage capacity (HSC>5.0 wt %), presenting an attractive hydrogen storage system.
- Zhou, Quan-Quan,Zou, You-Quan,Ben-David, Yehoshoa,Milstein, David
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p. 15487 - 15490
(2020/10/02)
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- PRECURSOR COMPOUNDS OF ESTER COMPOUNDS
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The present disclosure relates to compounds of the formula (I) which are precursor compounds of esters, whereby upon hydrolysis of the precursor compound, an ester compound is released. This ester precursor approach can be useful for applications where controlled release of, for example, ethyl formate, is beneficial.
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Paragraph 00133-00134
(2020/12/30)
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- Liquid phase esterification of levulinic acid into ethyl levulinate over sulphobenzylated nanoporous Al-SBA-15 catalyst
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Value added chemicals, fuels, and fuel additives can be obtained from cheap bio masses such as levulinic acid. Levulinic acid is the dehydration and hydrolysis products of pentoses and hexoses. The present work deals with the synthesis of sulphobenzylated Al-SBA-15, [SO3H-Bz-Al-SBA-15], characterization by various analytical techniques such as XRD, BET, FT-IR, TGA, DTA, FE-SEM/EDS and HR-TEM/EDX techniques and evaluation of catalytic activity towards esterification of levulinic acid to ethyl levulinate under mild and non corrosive conditions. Sulphonation of the aromatic ring of the benzyl group has been done in different amounts to get nanoporous x% SO3H-Bz-Al-SBA-15 catalysts where (x = 0.02, 0.04, 0.06, 0.08 and 0.10% w/w). Among them 0.08% SO3H-Bz-Al-SBA-15 catalyst showed the highest conversion of levulinic acid (100%) with the highest selectivity towards ethyl levulinate (100%). Esterification of levulinic acid has been carried out with different primary alcohols and all of them yielded 100% selectivity towards alkyl levulinate. However conversion level of levulinic acid was found to be different with different alcohols. Reaction conditions have been optimized. The results were compared with other supported catalysts and discussed.
- Kumaravel, Sakthivel,Thiripuranthagan, Sivakumar,Radhakrishnan, Ramakrishnan,Erusappan, Elangovan,Durai, Mani,Devarajan, Arulselvan,Mukannan, Arivanandhan
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p. 6965 - 6977
(2019/07/10)
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- Method for preparing ethyl acetate by hydrogenating acetic acid under catalysis of iridium complex
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The invention provides a method for preparing ethyl acetate by hydrogenating acetic acid under the catalysis of an iridium complex. The method is characterized in that a hydrogenation reaction is carried out with acetic acid as a raw material and the metal iridium complex as a catalyst. The method concretely comprises the following steps: weighing the acetic acid and the iridium complex, and carrying out a hydrogenation reduction reaction with hydrogen as a reducing agent at 90-150 DEG C for 0.5-72 h, wherein a mass ratio of the iridium complex to the acetic acid is 0.00001-0.1, and the hydrogen pressure is 1.0-10.0 MPa. The method has the advantages of simplicity in reaction operation, high product selectivity, and easiness in separation of the product.
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Paragraph 0012-0021
(2019/07/01)
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- Aerobic Self-Esterification of Alcohols Assisted by Mesoporous Manganese and Cobalt Oxide
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Aerobic self-esterification of primary alcohols catalyzed by mesoporous metal oxides (manganese and cobalt oxides) is reported under base and solvent free conditions. For a range of aliphatic alcohols, up to 90 % conversions to esters was achieved. The catalytic reaction is likewise applicable to neat aldehydes as substrates with yields of up to 86 %. High pressure batch reaction for ethanol to ethyl acetate led to 22 % yield. Isotope labeling studies indicated decarboxylation on the catalyst surface. Mechanistic and kinetic experiments implicate oxygen rebound and α-carbon removal as intermediate steps. Mesoporous cobalt oxide showed about 20 % higher catalytic activity compared to mesoporous manganese oxide.
- Moharreri, Ehsan,Biswas, Sourav,Deljoo, Bahareh,Kriz, David,Lim, Seyoung,Elliott, Sarah,Dissanayake, Shanka,Dabaghian, Marina,Aindow, Mark,Suib, Steven L.
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p. 3413 - 3422
(2019/08/01)
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- HOMOGENEOUS IRON CATALYSTS FOR THE CONVERSION OF ETHANOL TO ETHYL ACETATE AND HYDROGEN
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Iron-based homogeneous catalysts, supported by pincer ligands, are employed in the catalytic dehydrocoupling of ethanol to produce ethyl acetate and hydrogen. As both ethanol and ethyl acetate are volatile materials, they can be readily separated from the catalyst by applying vacuum at room temperature. The hydrogen by-product of the reaction may be isolated and utilized as a feedstock in other chemical transformations.
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Paragraph 0084-0092
(2019/02/15)
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- Transfer Hydrogenation of Carbon Dioxide to Methanol Using a Molecular Ruthenium-Phosphine Catalyst
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Transfer hydrogenation using molecular catalysts has become a powerful tool in synthetic chemistry and a wide range of unsaturated substrates can be reduced with this protocol. Whereas reactions using iso-propanol as hydrogen donor are already well established, recent examples demonstrate the possibility to use linear alcohols from renewable resources. Herein, the first effective transfer hydrogenation of the challenging substrate carbon dioxide (CO2) directly to methanol is described, applying a molecular ruthenium catalyst and linear alcohols as the hydrogen source. In neat ethanol, TONs up to 121 are achieved under moderate pressures of CO2. Moreover, systematic investigations enable to propose initial acceptorless dehydrogenation of the alcohol, followed by the reduction of CO2 to methanol via ethyl formate, as mechanistic basis.
- Westhues, Niklas,Klankermayer, Jürgen
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p. 3371 - 3375
(2019/07/12)
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- System and method of dehydrogenative coupling
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Dehydrogenative coupling can be achieved in nearly quantitative conversions and yields using a membrane reactor.
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Page/Page column 4; 8
(2019/12/25)
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- Ethanol dehydrogenative reactions catalyzed by copper supported on porous Al-Mg mixed oxides
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Mixed aluminum and magnesium oxides (AlMgO) prepared by means of an emulsion-mediated sol-gel method was impregnated with copper nitrate solution and used in the ethanol dehydrogenative reactions to produce acetaldehyde and ethyl acetate. The emulsified system allowed to obtain a macro-mesoporous support that resulted in an outstanding dispersion of copper. The porous catalyst was about 3 times more active than the non-porous counterpart, due to the formation on the support's surface of Cu0 together with the more active Cu+ species. In fact, the simultaneous presence of Cu+ and Cu0 were advantageous for the catalytic performance, as the turnover frequencies, were 122 and 166 h-1 for the non-porous reference catalyst and for the porous one, respectively. Both catalysts deactivated due to copper particles sintering, however the porous one deactivated less, as a consequence of the better dispersion of the Cu species on the macro and mesoporous support. Acetaldehyde was the main product, however by increasing the contact time by 6.6 times, the conversion of ethanol on the non-porous catalyst reached about 90% with a selectivity to ethyl acetate of 20% by means of the coupling reaction of ethanol and acetaldehyde. The selectivity to ethyl acetate was favoured on an increased support/copper interface that is given by larger copper particles.
- Petrolini, Davi D.,Cassinelli, Wellington H.,Pereira, Cristiane A.,Urquieta-González, Ernesto A.,Santilli, Celso V.,Martins, Leandro
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p. 3294 - 3302
(2019/02/10)
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- Ethanol to Butanol Conversion over Bifunctional Zeotype Catalysts Containing Palladium and Zirconium
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Abstract: A study of the kinetics of ethanol conversion in the presence of Zr-containing zeolites BEA doped with palladium particles has revealed the order of formation of the main reaction products. It has been shown that the primary processes are ethanol dehydrogenation to acetaldehyde on Pd sites and ethanol dehydration to diethyl ether on the acid sites of the catalyst. After that, acetaldehyde undergoes the aldol–croton condensation reaction to form crotonal, which is hydrogenated to butanol on the metal sites. Butanol, in turn, is dehydrated into butenes, which undergo hydrogenation to butane. The presence of hydrogen in the gas phase leads to the displacement of ethanol from the metal surface and prevents the formation of surface carbonates and acetates. It has been found that hydrogen significantly accelerates ethanol dehydration owing to a decrease in the activation energy, which can be attributed to hydrogen spillover to the zeolite. The addition of water inhibits all acid-catalyzed reactions owing to competitive adsorption on acid sites and thereby decreases the butanol yield and the ethanol conversion.
- Kots,Zabilska,Grigor’ev, Yu. V.,Ivanova
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p. 925 - 934
(2019/08/20)
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- Ethanol aerobic and anaerobic oxidation with FeVO4 and V2O5 catalysts
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This study compares the aerobic and anaerobic transformation of ethanol using FeVO4 and V2O5 catalysts. Despite their different structure, the two oxides showed very similar catalytic performances and their main product was acetaldehyde. However, in the absence of oxygen, the catalysts produced an equimolar amount of ethane and acetaldehyde, and this aspect has been little studied in the literature. In-situ XPS and DRIFT spectroscopy studies showed that the active species for the disproportionation of the alcohol into ethane and aldehyde was the reduced V3+ ion; nevertheless, the Fe in the FeVO4 catalysts was responsible for directing the reduction of metals toward the formation of a Fe-V-O spinel phase which was homogeneous and more stable than V2O5. Moreover, an in-situ DRIFT spectroscopy study showed that ethanol adsorbs in different ways on the surface of the catalysts during the reduction of samples (anaerobic reaction), forming H-bonded and dissociated ethoxy species, and giving rise to new surface OH groups that participate in the aldehyde/alkane formation. To conclude, a new mechanism of hydrogen transfer for the anaerobic ethanol disproportionation into ethane and acetaldehyde is proposed. This research completes the picture about ethanol oxidation to acetaldehyde on V-based catalysts, demonstrating that the catalytic behavior is mainly affected by the oxidation degree of the vanadium species which, in turn, depends on the reaction environment, and not on the structure itself.
- Malmusi, Andrea,Velasquez Ochoa, Juliana,Tabanelli, Tommaso,Basile, Francesco,Lucarelli, Carlo,Agnoli, Stefano,Carraro, Francesco,Granozzi, Gaetano,Cavani, Fabrizio
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p. 139 - 147
(2018/11/26)
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- Esterification of Tertiary Amides by Alcohols Through C?N Bond Cleavage over CeO2
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CeO2 has been found to promote ester forming alcoholysis reactions of tertiary amides. The present catalytic system is operationally simple, recyclable, and it does not require additives. The esterification process displays a wide substrate scope (>45 examples; up to 93 % isolated yield). Results of a density functional theory (DFT) study combined with in situ FT-IR observations indicate that the process proceeds through rate limiting addition of a CeO2 lattice oxygen to the carbonyl group of the adsorbed acetamide species with energy barrier of 17.0 kcal/mol. This value matches well with experimental value (17.9 kcal/mol) obtained from analysis of the Arrhenius plot. Further studies by in situ FT-IR and temperature programmed desorption using probe molecules demonstrate that both acidic and basic properties are important, and consequently, CeO2 showed the best performance for the C?N bond cleavage reaction.
- Toyao, Takashi,Nurnobi Rashed, Md.,Morita, Yoshitsugu,Kamachi, Takashi,Hakim Siddiki,Ali, Md. A.,Touchy,Kon, Kenichi,Maeno, Zen,Yoshizawa, Kazunari,Shimizu, Ken-ichi
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p. 449 - 456
(2018/09/11)
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- A acetic acid ethyl ester (by machine translation)
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A acetic acid ethyl ester synthetic method, which belongs to the organic chemical and technical field of drug synthesis. The steps of: sequentially according to the acetic acid, sodium hydroxide and acetic acid soaking the sequence of the large hole type cation exchange resin soaking, the soaking and rinsing with water, and the resin of the soda pH neutral, followed by filtering and removing sticking on large-type cation exchange resin on the surface of the water, pre-processing resin; and the acetic acid pretreatment resin input in toluene and ethyl trailer drop under the state of the esterification reaction, after the reaction filter, to separate the resin, to be toluene toluene fluid cooling after filtering, to islet unreacted acetic acid, the acetic acid ethyl ester toluene fluid washing, then pressure reducing condensation and recycle the solvent, followed by distillation, by ethyl acetate. Advantages: high yield, after treatment is convenient, pollution-free, can be repeated regeneration using; resin directly repeatedly, solvent recycled, not only can save resources, but also can reflect the environmental protection. (by machine translation)
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Paragraph 0023
(2019/05/11)
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- A method for synthesis of ethyl acetate (by machine translation)
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A method for synthesis of ethyl acetate, the organic chemical and technical field of drug synthesis. The steps of: sequentially according to the acetic acid, sodium hydroxide and acetic acid soaking the sequence of the large hole type cation exchange resin soaking, the soaking and rinsing with water, and the resin of the soda pH neutral, followed by filtering and removing sticking on large-type cation exchange resin on the surface of the water, pre-processing resin; and the acetic acid pretreatment resin input in toluene and ethyl trailer drop under the state of the esterification reaction, after the reaction filter, to separate the resin, to be toluene toluene fluid cooling after filtering, to islet unreacted acetic acid, ethyl acetate or toluene fluid to wash, then pressure reducing condensation and recycle the solvent, then distillation, ethyl acetate. Advantages: high yield, after treatment is convenient, pollution-free, can be repeated regeneration using; resin directly repeatedly, solvent recycled, not only can save resources, but also can reflect the environmental protection. (by machine translation)
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Paragraph 0019; 0021-0022
(2019/06/08)
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- Catalytic Hydrogenation of Acetic Acid to Acetaldehyde: Synergistic Effect of Bifunctional Co/Ce-Fe Oxide Solid Solution Catalysts
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The large-scale industrial production of acetic acid (HAc) from carbonylation of methanol has enabled intense research interest from direct hydrogenation of HAc to acetaldehyde (AA). Herein, a series of cerium-iron oxide solid solution supported metallic cobalt catalysts were prepared by modified sol-gel method and were applied in gas-phase hydrogenation of HAc to AA. A synergistic effect between the hydrogenation metal cobalt and Ce-Fe oxide solid solution is revealed. Specifically, oxygen vacancies provide the active sites for adsorption of HAc, while highly uniformly dispersed metallic Co adsorbs H2 and activates the reduction of HAc into AA. Moreover, the metallic Co can also assist the cyclical conversion between Fe3+/Fe2+ and Ce3+/Ce4+ on the surface of Ce1-xFexO2-δ supports. The unique effect substantially enhances the ability of the support material to rapidly capture oxygen atoms from HAc. It is found that the catalyst of 5% Co/Ce0.8Fe0.2O2-δ with the highest concentration of oxygen vacancy presents the best catalytic performance (i.e. acetaldehyde yield reaches 49.9%) under the optimal reaction conditions (i.e. 623 K and H2 flow rate = 10 mL/min). This work indicates that the Co/Ce-Fe oxide solid solution catalyst can be potentially used for the selective hydrogenation from HAc to AA. The synergy between the metallic Co and Ce1-xFexO2-δ revealed can be extended to the design of other composite catalysts.
- Li, Naixu,Zhang, Qi,Bibi, Rehana,Shen, Quanhao,Ngulube, Richard,Liu, Yunyi,Zhou, Jiancheng
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supporting information
p. 709 - 719
(2019/06/05)
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- PHENANTHROLINE BASED PINCER COMPLEXES USEFUL AS CATALYSTS FOR THE PREPARATION OF METHANOL FROM CARBONDIOXIDE
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The present invention relates to a novel phenonthroline based pincer complexes and process for preparation thereof. The present invention also provides a one pot process for the conversion of carbon dioxide to methanol in the presence of a molecularly defined pincer-type single-site Ru-catalyst and secondary amine. Further the present invention provides the use of phenonthroline based pincer complexes for the esterification of alcohols and hydrogenation of esters under mild conditions.
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Paragraph 0135
(2018/04/02)
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- SNS-Ligands for Ru-Catalyzed Homogeneous Hydrogenation and Dehydrogenation Reactions
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A detailed study of literature-known and novel S-containing pincer-type ligands for ruthenium-catalyzed homogeneous hydrogenation and dehydrogenation reactions was carried out. The scope and limitations of these catalysts were carefully investigated, and it was shown that simple bench-stable SNS-Ru complexes can be used to facilitate the hydrogenation of a variety of different substrates at a maximum H2 pressure of 20 bar under operationally simple, easy to scale up, glovebox-free conditions by using starting materials and reagents that do not require any special purification prior to use. It was also shown that such complexes can be used to catalyze the dehydrogenative coupling of alcohols and amines to get amides as well as for the dehydrogenative dimerization of alcohols to esters.
- Sch?rgenhumer, Johannes,Zimmermann, Axel,Waser, Mario
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supporting information
p. 862 - 870
(2018/06/18)
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- H2 photo-production from methanol, ethanol and 2-propanol: Pt-(Nb)TiO2 performance under UV and visible light
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In this work we analyzed the photo-production of hydrogen using titania-based systems able to profit from UV and visible light photons. For this purpose, we prepared Niobium-doped titania and a titania reference by a microemulsion method, subjected these oxide precursors to calcination and subsequently introduced Pt as co-catalyst by a chemical reduction method. These materials were characterized in terms of the structural and morphological properties of the oxide and metal phases. Using these materials, we measured the reaction rate and quantum efficiency of the hydrogen photo-production using methanol, ethanol, and 2-propanol as sacrificial agents. Significant activity enhancement was observed in the Niobium-doped material with respect to the titania reference material. The study focuses on interpreting the differences presented (between the two samples) among the three alcohols in the hydrogen yield and provides a physico-chemical study to understand the roots of the activity. Such study was mainly based on the analysis of the reaction mechanism using in-situ infrared spectroscopy together with the analysis of the energetics of the reaction taking into account the fate of the sacrificial alcohol during reaction.
- Fontelles-Carceller, Olga,Mu?oz-Batista, Mario J.,Conesa, José Carlos,Kubacka, Anna,Fernández-García, Marcos
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- Tailoring the Selectivity of Bio-Ethanol Transformation by Tuning the Size of Gold Supported on ZnZr10Ox Catalysts
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The selective bio-ethanol cascade transformation to hydrocarbons over multifunctional catalysts is a highly promising sustainable pathway to high-value chemicals and fuels. However, principles to control the selectivity of the bio-ethanol transformation using the effects of the size of nanoparticle catalysts have remainedlargely unexplored. Here, using bio-ethanol transformation reactions catalyzed by Au/ZnZr10Ox as examples, we demonstrate that changing the fashion of gold loading enables control over product distribution. Our results reveal that larger gold particles tendto show much higher selectivity for 1,3-butadiene, whereas smaller gold nanoparticles favor the formation of acetaldehyde.This study uncovers general principles for tailoring the selectivity of bio-ethanol transformation by carefully engineering the size of gold. It opens a new avenue for the rational design of multifunctional catalysts to enhance the production of desired reaction products in complex cascade reaction sequences.
- He, Rong,Men, Yong,Liu, Jixing,Wang, Jinguo,An, Wei,Huang, Xiaoxiong,Song, Weiyu,Liu, Jian,Dai, Sheng
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p. 3969 - 3973
(2018/09/25)
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- Single-Pot Synthesis of Alkyl-Substituted Quinolines and Indoles via Photoinduced Oxidation of Primary Alcohols
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Single-pot synthesis of alkyl-substituted quinolines and indoles has been performed via photoinduced oxidation of primary aliphatic alcohols (C2–C5) and condensation of the aldehydes (products of the alcohols oxidation) with aniline under the action of iron-containing catalysts and inorganic oxidants. The synthesis was the most efficient in the presence of FeCl3·6H2O as catalyst and 10% aqueous solution of NaOCl as oxidant with irradiation by Hg lamp. The synthesis mechanism through photoinduced oxidation of primary aliphatic alcohol has been suggested.
- Makhmutov
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p. 892 - 897
(2018/07/06)
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- A nitrogen-doped PtSn nanocatalyst supported on hollow silica spheres for acetic acid hydrogenation
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A novel PtSn/NHSS bimetallic catalyst with N-doped hollow silica spheres as the support was synthesized for the gas-phase hydrogenation of acetic acid to ethanol. Its specific activity was 30% higher than that of PtSn/SiO2 due to the enhanced surface exposure of Pt active sites, induced by the strong interaction between Pt and N.
- Zhou, Jiahua,Zhao, Yujun,Zhang, Jian,Wang, Yue,Gutiérrez, Oliver Y.,Wang, Shengnian,Li, Zhengxiang,Jin, Peng,Wang, Shengping,Ma, Xinbin,Lercher, Johannes A.
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supporting information
p. 8818 - 8821
(2018/08/17)
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