- Microporous zirconia-silica mixed oxides made by sol-gel as catalysts for the liquid-phase oxidation of olefins with hydrogen peroxide
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Microporous zirconia-silica mixed oxides were prepared by sol-gel method and their reactivity in the oxidation of olefins with hydrogen peroxide was examined. The catalysts were characterized via BET methods, thermogravimetric analysis, XRD, UV-vis spectroscopy and TPD of ammonia. They had high surface areas, were amorphous and possessed only mild surface acidity. The reactivity order observed in the oxidation of olefins is a strong indication that the reaction proceeds through a heterolytic mechanism in which a nucleophilic olefin attacks a surface-electron-poor zirconium peroxo species. Although in all cases, the epoxide is likely involved as the primary reaction oxidation product. The acidity of the medium and/or support led to the opening of the oxirane ring. In the absence of solvent, the catalysts showed high selectivity (>99% glycol) at moderate temperature. In general, the activity and selectivity of the catalysts appear to be controlled by an appropriate polarity of the medium in which the reaction is carried out, by the polarity/acidity of the surface, and by the possibility to carry out the reaction at lower temperatures where the acidity effects of the hydrogen peroxide and silica matrix could be minimized.
- Palazzi, Chiara,Oliva, Liliana,Signoretto, Michela,Strukul, Giorgio
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- Support morphology-dependent catalytic activity of the Co/CeO2catalyst for the aqueous-phase hydrogenation of phenol
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Herein, three Co/CeO2catalysts with various support morphologies were prepared by Co2(CO)8decomposition at a low temperature of 180 °C on the ceria plane such as CeO2nanocubes (c-CeO2), nanorods (r-CeO2), and nanopolyhedrons (p-CeO2). The Co/r-CeO2catalyst shows a much higher phenol conversion (82.5%) than Co/c-CeO2(47.9%) and Co/p-CeO2(24.7%) at 150 °C and 3 MPa H2in water. We demonstrate that the less hydrophilic Co/r-CeO2catalyst inhibits the adsorption of water and further promotes the adsorption of phenol. Moreover, the morphology effect and oxygen vacancies in different chemical environments of the support provide active sites for the dissociation and adsorption of phenol. The high concentration of oxygen vacancies exposed on the high active crystal plane leads to more efficient catalytic activity for the hydrogenation of phenol.
- Hu, Bin,Lu, Jinzhi,Ma, Zhanwei,Wei, Xuemei,Zhang, Qinsheng
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- Target-Architecture Engineering of a Novel Two-dimensional Metal-Organic Framework for High Catalytic Performance
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A novel 2D-MOF, [Zn(L1)(oba)], an effective heterogeneous H-bond donor catalyst, based on carbohydrazide moiety (L1), was synthesized. Remarkable enhanced catalytic activity was achieved for methanolysis of epoxides by applying two effective strategies: (i) increasing the acidic strength of the H-bond donors and (ii) providing more accessible active sites within the framework.
- Afshariazar, Farzaneh,Morsali, Ali
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- Metalation of Catechol-Functionalized Defective Covalent Organic Frameworks for Lewis Acid Catalysis
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Covalent organic frameworks (COFs) have emerged as a fascinating crystalline porous material and are widely used in the field of catalysis. However, developing simple approaches to fabricate conjugated COFs with specific functional groups remains a significant challenge. In this study, the construction of defective COF-LZU1 with Lewis acid sites embedded into the frameworks is fulfilled by a facile solvent-assisted ligand exchange method. A monodentate ligand, protocatechualdehyde, is successfully introduced into the skeleton of COF-LZU1, which endows the defects in the structure of COF-LZU1 via replacement of the original coordinated benzene-1,3,5-tricarbaldehyde ligand. As-synthesized defective COF-LZU1 decorated with protocatechualdehyde is rich of free hydroxy groups for chelating with active metal ions. Specifically, after combining with Fe3+, the defective COF-LZU1 shows excellent activity in catalytic alcoholysis of epoxides under mild conditions. The method reported here will open up the opportunity to incorporate different functional groups into COFs and enrich the strategies for creating new types of porous catalysts.
- Gu, Lin,Han, Jianyu,Liu, Haitao,Shi, Yanan,Tang, Zhiyong,Yang, Zhongjie,Zhang, Xiaofei
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- Electrocatalytic hydrogenation of lignin monomer to methoxy-cyclohexanes with high faradaic efficiency
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Developing efficient renewable electrocatalytic processes in chemical manufacturing is of commercial interest, especially from biomass-derived feedstock. Selective electrocatalytic hydrogenation (ECH) of biomass-derived lignin monomers to high-value oxygen-functional compounds is promising towards achieving this goal. However, ECH has to date lacked the satisfied selectivity to upgrade lignin monomers to high-value oxygenated chemicals due to the reduction of vulnerable ?OCH3 that exists in most lignin monomers. Herein we report carbon-felt supported ternary RhPtRu catalysts with a record faradaic efficiency (FE) of 62.8% and selectivity of 91.2% to methoxy-cyclohexanes (2-methoxy-cyclohexanol and 2-methoxy-cyclohexanone) from guaiacol, via a strong inhibition effect on the cleavage of the methoxy group, representing the best performance compared to previous reports. We further conducted a brief TEA to demonstrate a profitable ECH of guaiacol to high-value methoxy-cyclohexanes using our designed RhPtRu ternary catalysts.
- Chen, Henan,Kumar, Mohan,Liang, Baiyao,Peng, Tao,Wang, Miao,Yang, Chenxin,Zhang, Yun,Zhao, Wei
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supporting information
p. 142 - 146
(2022/01/19)
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- Chemoselective and Tandem Reduction of Arenes Using a Metal–Organic Framework-Supported Single-Site Cobalt Catalyst
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The development of heterogeneous, chemoselective, and tandem catalytic systems using abundant metals is vital for the sustainable synthesis of fine and commodity chemicals. We report a robust and recyclable single-site cobalt-hydride catalyst based on a porous aluminum metal–organic framework (DUT-5 MOF) for chemoselective hydrogenation of arenes. The DUT-5 node-supported cobalt(II) hydride (DUT-5-CoH) is a versatile solid catalyst for chemoselective hydrogenation of a range of nonpolar and polar arenes, including heteroarenes such as pyridines, quinolines, isoquinolines, indoles, and furans to afford cycloalkanes and saturated heterocycles in excellent yields. DUT-5-CoH exhibited excellent functional group tolerance and could be reusable at least five times without decreased activity. The same MOF-Co catalyst was also efficient for tandem hydrogenation–hydrodeoxygenation of aryl carbonyl compounds, including biomass-derived platform molecules such as furfural and hydroxymethylfurfural to cycloalkanes. In the case of hydrogenation of cumene, our spectroscopic, kinetic, and density functional theory (DFT) studies suggest the insertion of a trisubstituted alkene intermediate into the Co–H bond occurring in the turnover limiting step. Our work highlights the potential of MOF-supported single-site base–metal catalysts for sustainable and environment-friendly industrial production of chemicals and biofuels.
- Akhtar, Naved,Begum, Wahida,Chauhan, Manav,Manna, Kuntal,Newar, Rajashree,Rawat, Manhar Singh
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supporting information
(2022/01/19)
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- Pt and Ru Catalysts Based on Porous Aromatic Frameworks for Hydrogenation of Lignin Biofuel Components
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Abstract: A platinum catalyst and a ruthenium catalyst were synthesized from a porousaromatic framework, namely PAF-30. The catalyst properties were examined inhydrogenation of phenol and guaiacol at 80–250°C and at a hydrogen pressure of30 atm in the presence of various solvents. Significant effects of the reactionmedium, process conditions, and catalyst morphology on the reaction mechanismwere demonstrated. Reaction conditions optimal for complete conversion of phenoland guaiacol to hydrogenation products were selected for both catalysts. [Figure not available: see fulltext.]
- Cherednichenko, K. A.,Kalinina, M. A.,Karakhanov, E. A.,Kulikov, L. A.,Makeeva, D. A.,Maximov, A. L.
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p. 711 - 720
(2021/08/03)
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- Production of alkoxyl-functionalized cyclohexylamines from lignin-derived guaiacols
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The transformation of renewable lignin-based platform chemicals into value-added nitrogen-containing compounds is an emerging strategy for lignin utilization. However, multi-reactive sites on these platform chemicals make it challenging to control the product selectivity, thereby resulting in limited success. In this work, we developed the reductive-coupling of guaiacol, a typical lignin-based platform chemical, with amines and H2 to synthesize methoxy-functionalized cyclohexylamines. It was demonstrated that Pd/C was a very efficient catalyst for this kind of reaction, and high yields of the target products can be obtained. Notably, this methodology can be applied for the reductive-coupling of various guaiacol analogues with amines to synthesize alkoxyl-functionalized cyclohexylamines with high yields. A mechanism study revealed that the reaction occurred through the generation of 2-methoxycyclohexanone and its subsequent reductive amination. This journal is
- Han, Buxing,He, Mingyuan,Mei, Xuelei,Song, Jinliang,Wu, Haihong,Wu, Wei,Xu, Caiyun,Xu, Jiao,Zhang, Kaili,Zheng, Bingxiao
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supporting information
p. 8441 - 8447
(2021/11/17)
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- Cross-linked poly(N-vinylpyrrolidone)-titanium tetrachloride complex: A novel stable solid TiCl4 equivalent as a recyclable polymeric Lewis acid catalyst for regioselective ring-opening alcoholysis of epoxides
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Cross-linked poly(N-vinylpyrrolidone) resin beads were prepared as macromolecular ligand precursors by suspension copolymerization of N-vinyl-2-pyrrolidone and N,N′-methylenebisacrylamide (MBA) as a crosslinking agent in water. Subsequently, the resulting polymer carrier precursor was readily combined with titanium tetrachloride to form a stable polymeric coordination complex (PNVP/TiCl4), and this novel stable TiCl4 equivalent evaluated as a heterogeneous and reusable solid Lewis acid catalyst for the regio-and stereoselective nucleophilic ring opening of various epoxides with various alcohols to prepare β-alkoxy alcohols in excellent yields without generating any waste. The MBA-cross-linked PNVP and resultant catalyst were characterized by Fourier transform infrared spectroscopy (FT–IR), field-emission scanning electron microscope (FE–SEM), energy dispersive X-ray (EDX), inductively coupled plasma (ICP), and thermogravimetric analysis (TGA) techniques. Moreover, the catalyst is very stable, easily separated, and reused at least five times without significant loss of activity. In terms of scope, yields, the amount of catalyst used, and reaction time, the PNVP-TiCl4 complex catalyst is an improvement over previously reported heterogeneous catalysts for ring opening of epoxides methods. Further, the experimental outcome revealed that using the copolymer beads as carriers with a high percentage of crosslinking and the high mesh size leads had an adverse effect on the reaction rate.
- Rahmatpour, Ali,Sajjadinezhad, Seyed Mehrzad
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- MBA-cross-linked poly(N-vinyl-2-pyrrolidone)/ferric chloride macromolecular coordination complex as a novel and recyclable Lewis acid catalyst: Synthesis, characterization, and performance toward for regioselective ring-opening alcoholysis of epoxides
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A novel macromolecular-metal coordination complex, MBA-cross-linked PNVP/FeCl3 material was fabricated by immobilization of water intolerant ferric chloride onto the porous cross-linked poly(N-vinyl-2-pyrrolidone) carrier beads as a macromolecular ligand or carrier which was prepared by suspension free-radical copolymerization of N-vinyl-2-pyrrolidone (NVP) and N,N′-methylene bis-acrylamide (MBA) as a crosslinking agent in water. The obtained PNVP/FeCl3 was characterized by UV/vis and FT-IR spectroscopies, TGA, FE-SEM, EDX, and ICP techniques. This heterogenized version of ferric chloride is a convenient and safe alternative to highly water intolerant ferric chloride. The catalytic performance of (PNVP/FeCl3) as an efficient and recyclable polymeric Lewis acid catalyst was appropriately probed in the regio-and stereoselective nucleophilic ring opening of various epoxides with various alcohols in excellent yields with TOF up to 182.48 h?1 without generating any waste. The activity data indicate that this heterogeneous catalyst is very active and could be easily recovered, and reused at least six times without appreciable loss of activity indicating its stability under experimental conditions.
- Rahmatpour, Ali,Zamani, Maryam
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- Role of Catalyst Support's Physicochemical Properties on Catalytic Transfer Hydrogenation over Palladium Catalysts
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Catalytic transfer hydrogenation (CTH) is a promising reaction for valorisation of bio-based feedstocks via hydrogenation without needing to use H2. Unlike standard hydrogenation, CTH occurs via dehydrogenation (DHD) of a hydrogen donor (H-donor) and hydrogenation (HYD) of a substrate. Therefore, the “ideal” CTH catalyst must balance the catalysis of both reactions to maximize the hydrogen transfer between H-donor and substrate with minimal H2 loss to gas (high atom efficiency). Additionally, the H-donor must be highly stable to prevent secondary reactions with the substrate. Herein we study the impact of the catalyst's properties on CTH of guaiacol using bicyclohexyl, a liquid organic hydrogen carrier, as a H-donor. The reaction was promoted by palladium dispersed on three typical support materials (γ-Al2O3, MgO, and SiO2). The performance of these catalysts in the conversion of bicyclohexyl and guaiacol was evaluated, allowing to estimate the H-transfer efficiency, as well as the potential for recycling the spent H-donor (bicyclohexyl). The apparent activation energies for DHD of bicyclohexyl and HYD of guaiacol revealed that slow DHD combined with fast HYD, as is the case with Pd/MgO, favours hydrogen transfer efficiency and selectivity towards hydrogenated products. In addition, an investigation of the DHD of bicyclohexyl and HYD of guaiacol independently showed that the affinity between the organic molecules and the support significantly impacts CTH. Indeed, Pd/SiO2 was highly active for both reactions individually and almost inactive for CTH. Consequently, these findings highlight the importance of the interaction between solvent-substrate-support in designing catalysts for transfer hydrogenation.
- Batalha, Nuno,Fraga, Gabriel,Hasan, M. D.,Konarova, Muxina,Laycock, Bronwyn,Pratt, Steven,Santos, Mirella S.
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p. 5191 - 5202
(2021/10/29)
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- The Effect of Sulfonate Groups in the Structure of Porous Aromatic Frameworks on the Activity of Platinum Catalysts Towards Hydrodeoxygenation of Biofuel Components
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Abstract: Platinum catalysts based on porous aromatic frameworks (PAF-30 and PAF-30–SO3H) have been synthesized. Properties of the obtained catalysts have been assessed via hydrogenation of guaiacol, veratrole, and pyrocatechol at 250°С and hydrogen pressure 3.0 MPa in isopropanol medium. It has been shown that the presence of acidic sites in the catalyst significantly increases the yield of deoxygenation products. The effect of the substrate structure on the rate of its hydrodeoxygenation and the mechanism of the occurring processes have been studied. [Figure not available: see fulltext.]
- Kalinina,Kulikov,Cherednichenko,Maximov,Karakhanov
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p. 1061 - 1070
(2021/09/06)
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- Understanding the mechanism of N coordination on framework Ti of Ti-BEA zeolite and its promoting effect on alkene epoxidation reaction
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The function of ammonium salts on the epoxidation performance over Ti-BEA zeolite was investigated in detail. Experiments of alkene epoxidation, side reactions of epoxide and decomposition of H2O2 with or without ammonium salts were designed, and the UV-Vis spectroscopy was employed to analyze the structure of Ti-hydroperoxo species. It is revealed that the ammonia (or amines) dissociated from the ammonium salt would chelate with the linear Ti-η1(OOH) species and form a bridged Ti-η2(OOH)-R species, which is more stable, more weaker in epoxide adsorption and acidity as well. Therefore, side reactions and H2O2 decomposition would be suppressed, and both alkene conversion and epoxide selectivity would be promoted simultaneously. On the other hand, the excessive NH3?H2O (NH3/Ti>1) or NaOH bond with the Ti-η2(OOH)-R species and generate salt-like Ti-η2(OO)-M+ species, resulting in the deactivation of Ti active center. While for ammonium salts, e.g. NH4Cl, the limited dissociation degree along with the acidic environment help the Ti active center to maintain in highly active. In short, this work provides a practical Ti active center tuning method for Ti-BEA zeolite, as well as a thorough understanding of its Ti-hydroperoxo species.
- Liang, Xiaohang,Liu, Dan,Luo, Yibin,Peng, Xinxin,Shu, Xingtian,Xia, Changjiu
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- Catalytic transfer hydrogenation of 4-O-5 models in lignin-derived compounds to cycloalkanes over Ni-based catalysts
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There is an urgent need to develop a selective hydrogenolysis of Caryl-O bonds in lignin to produce valued-added chemicals and fuels. Recently, hydrogen has been used in the hydrogenation reaction, which hides inevitable danger and is not economical. Therefore, isopropanol, as a hydrogen-donor solvent, is employed for aryl ether hydrogenolysis in lignin models over nickel supported on a carbon nanotube (CNT). Except for aromatic ether (4-O-5), the Ni/CNT catalyst is also found to be suitable for alkyl-aryl ether (α-O-4 and β-O-4) cleavage in control experiments. The physicochemical characterizations were carried out by means of H2-temperature-programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. The catalyst can be magnetically recovered and efficiently reused for five consecutive recycling tests in the transfer hydrogenation of aromatic ethers. A mechanism study indicated that the hydrogenolysis cleavage of the ether bond is the first step in the reaction process, and hydrogenation of aromatic rings is only a successive step in which phenol and benzene are intermediate states and are then further hydrogenated. Furthermore, it has been demonstrated that aryl groups play an important role in the hydrogenation of phenol in the competitive catalytic hydrogenation reaction of phenol.
- Chen, Changzhou,Liu, Peng,Xia, Haihong,Zhou, Minghao,Jiang, Jianchun
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p. 582 - 591
(2020/12/01)
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- Ruthenium- and Palladium-Containing Catalysts Based on Mesoporous Polymer Nanospheres in Guaiacol Hydrogenation
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Abstract: Catalysts Pd-NSMR and Ru-NSMR based on palladium and ruthenium nanoparticles deposited on a nanospherical mesoporous resorcinol-formaldehyde polymer are synthesized. It is shown that the average size of polymer particles is 220–250 nm and the average size of palladium and ruthenium nanoparticles is 7.2 and 2.2 nm, respectively. The catalysts are tested in guaiacol hydrogenation at a temperature of 200°С and a hydrogen pressure of 4.0 MPa. It is demonstrated that the ruthenium catalyst shows higher activity in guaiacol hydrogenation.
- Boronoev, M. P.,Karakhanov, E. A.,Maximov, A. L.,Shakirov, I. I.,Zolotukhina, A. V.
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p. 1136 - 1140
(2020/10/14)
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- Selective hydrogenation of lignin-derived compounds under mild conditions
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A key challenge in the production of lignin-derived chemicals is to reduce the energy intensive processes used in their production. Here, we show that well-defined Rh nanoparticles dispersed in sub-micrometer size carbon hollow spheres, are able to hydrogenate lignin derived products under mild conditions (30 °C, 5 bar H2), in water. The optimum catalyst exhibits excellent selectivity and activity in the conversion of phenol to cyclohexanol and other related substrates including aryl ethers.
- Chen, Lu,Van Muyden, Antoine P.,Cui, Xinjiang,Laurenczy, Gabor,Dyson, Paul J.
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p. 3069 - 3073
(2020/06/17)
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- Highly Efficient Cleavage of Ether Bonds in Lignin Models by Transfer Hydrogenolysis over Dual-Functional Ruthenium/Montmorillonite
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Cleavage of ether bonds is a crucial but challenging step for lignin valorization. To efficiently realize this transformation, the development of robust catalysts or catalytic systems is required. In this study, montmorillonite (MMT)-supported Ru (denoted as Ru/MMT) is fabricated as a dual-functional heterogeneous catalyst to cleave various types of ether bonds through transfer hydrogenolysis without using any additional acids or bases. The prepared Ru/MMT material is found to efficiently catalyze the cleavage of various lignin models and lignin-derived phenols; cyclohexanes (fuels) and cyclohexanols (key intermediates) are the main products. The synergistic effect between electron-enriched Ru and the acidic sites on MMT contributes to the excellent performance of Ru/MMT. Systematic studies reveal that the reaction proceeds through two possible reaction pathways, including the direct cleavage of ether bonds and the formation of intermediates with one hydrogenated benzene ring, for all examined types of ether bonds, namely, 4-O-5, α-O-4, and β-O-4.
- Xue, Zhimin,Yu, Haitao,He, Jing,Zhang, Yibin,Lan, Xue,Liu, Rundong,Zhang, Luyao,Mu, Tiancheng
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p. 4579 - 4586
(2020/06/21)
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- The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Br?nsted acid catalysts
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The acid–base neutralization reaction of commercially available disodium 2,6-naphthalenedisulfonate (NDS, 2 equivalents) and the tetrahydrochloride salt of tetrakis(4-aminophenyl)methane (TAPM, 1 equivalent) in water gave a novel three-dimensional charge-assisted hydrogen-bonded framework (CAHOF, F-1). The framework F-1 was characterized by X-ray diffraction, TGA, elemental analysis, and 1H NMR spectroscopy. The framework was supported by hydrogen bonds between the sulfonate anions and the ammonium cations of NDS and protonated TAPM moieties, respectively. The CAHOF material functioned as a new type of catalytically active Br?nsted acid in a series of reactions, including the ring opening of epoxides by water and alcohols. A Diels–Alder reaction between cyclopentadiene and methyl vinyl ketone was also catalyzed by F-1 in heptane. Depending on the polarity of the solvent mixture, the CAHOF F-1 could function as a purely heterogeneous catalyst or partly dissociate, providing some dissolved F-1 as the real catalyst. In all cases, the catalyst could easily be recovered and recycled.
- Belokon, Yuri N.,Dmitrienko, Artem O.,Gak, Alexander S.,Gerasimov, Igor S.,Kuznetsova, Svetlana A.,Larionov, Vladimir A.,Li, Han,Medvedev, Michael G.,Nelyubina, Yulia V.,North, Michael,Saghyan, Ashot S.,Smol'yakov, Alexander F.,Zhereb, Vladimir P.
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supporting information
p. 1124 - 1134
(2020/07/10)
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- Low-Temperature Catalytic Hydrogenolysis of Guaiacol to Phenol over Al-Doped SBA-15 Supported Ni Catalysts
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Selective hydrogenolysis of aromatic carbon-oxygen (Caryl?O) bonds is a key strategy for the generation of aromatic chemicals from lignin. However, this process is usually operated at high temperatures and pressures over hydrogenation catalysts, resulting in a low selectivity for aromatics and an extra consumption of hydrogen. Here, a series of Al-doped SBA-15 mesoporous materials with different Si/Al molar ratios (Al-SBA-15) were prepared via a post-synthesis method using NaAlO2 as the Al source, and then Al-SBA-15 supported Ni catalysts (Ni/Al-SBA-15) were prepared by a deposition-precipitation method using urea as the hydrolysis reagent. The prepared supports and catalysts were extensively characterized using various techniques such as XRD, N2 adsorption/desorption, TEM, 27Al NMR, NH3-TPD, XPS, H2-TPR, and pyridine-FT-IR, and the catalysts were evaluated in the hydrogenolysis of the Caryl?O bond in guaiacol and lignin derived compounds under mild conditions. The effects of the Si/Al ratio in catalyst and reaction parameters on guaiacol conversion and product distribution were investigated in detail, associated with solvent effect. The incorporation of Al into the framework of SBA-15 can improve the Lewis acidity and the dispersion of the supported Ni particles and yet modulate the metal-support interactions, which are propitious to the hydrogenolysis of the Caryl?O bond in guaiacol. The catalyst Ni/Al-SBA-15 with a Si/Al molar ratio of 10 shows the best performance with a guaiacol conversion of 87.4 % and a phenol selectivity of 76.9 % under the mild conditions conducted, because of its proper acidity, suitable metal-support interactions, and high dispersion of the active species. The present study would stimulate research and development in multi-functional catalysts for the generation of valuable chemicals from biomass.
- Wang, Qiuyue,Chen, Yufang,Yang, Guanheng,Deng, Ping,Lu, Xinqing,Ma, Rui,Fu, Yanghe,Zhu, Weidong
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p. 4930 - 4938
(2020/08/26)
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- The role of acid and metal sites in hydrodeoxygenation of guaiacol over Ni/Beta catalysts
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Hydrodeoxygenation (HDO) of guaiacol over Ni metal supported on zeolites (H-Beta and H-ZSM-5) with different Si/Al ratios (12.5, 25, 175) and different metal loadings (2.3-23.4 wt%) was investigated in order to elucidate the role of catalyst acidity and the structure of Ni in the HDO reaction. Results show that the deoxygenation activity and product selectivity depend on the choice of support (acidity, pore size), level of metal loading, and reaction conditions. Guaiacol was deoxygenated in the presence of hydrogen with a maximum cyclohexane yield of 76% at a guaiacol conversion level of 100% over 15.7 wt% Ni/Beta-12.5 catalyst. Compared to Ni/ZSM-5 catalysts, Ni/Beta catalysts with mesopores facilitated the formation of coupling products (1,1′-bicyclohexyl). Under differential reaction conditions, we observed a linear relationship between deoxygenation activity and concentration of acid sites. Over catalysts containing small Ni particles, cyclohexane was formed as a result of a consecutive reduction of guaiacol to catechol and cyclohexane. At higher Ni-loading and consequently larger Ni particles, the selectivity towards cyclohexane increases with increased Ni loading. A higher concentration of nickel hydrides compared to smaller Ni sites was observed by H2-TPD and H2-FTIR over larger Ni species, and the nickel hydrides are believed to be crucial intermediates in the hydrogenation reaction. The 15.7 wt% Ni/Beta (Si/Al = 12.5) exhibits a promising HDO activity due to its good synergistic effect of hydrogenation and deoxygenation functions (high concentration nickel hydrides of and acid sites). In addition, based on the product distribution over catalysts containing mainly small Ni species and the Ni nanoparticles, two different reaction pathways were proposed, and the role of the acid sites and metal sites for each reaction route was discussed.
- Adesina, Adesoji,Kennedy, Eric,Li, Molly Meng-Jung,Setiawan, Adi,Stockenhuber, Michael,Yan, Penghui,Zhao, Guangyu
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p. 810 - 825
(2020/02/27)
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- Electrocatalytic Hydrogenation of Guaiacol in Diverse Electrolytes Using a Stirred Slurry Reactor
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Electrocatalytic hydrogenation (ECH) of guaiacol was performed in a stirred slurry electrochemical reactor (SSER) using 5 wt % Pt/C catalyst in the cathode compartment. Different pairs of acid (H2SO4), neutral (NaCl), and alkaline (NaOH) catholyte–anolyte combinations separated by a Nafion 117 cation exchange membrane, were investigated by galvanostatic and potentiostatic electrolysis to probe the electrolyte and proton concentration effect on guaiacol conversion, product distribution, and Faradaic efficiency. The acid–acid and neutral–acid pairs were found to be the most effective. In the case of the neutral–acid pair, proton diffusion and migration through the membrane from the anolyte to the catholyte supplies the protons required for ECH. Typically, the two major hydrogenation products were cyclohexanol and 2-methoxycyclohexanol. However, ECH at constant cathode superficial current density (?182 mA cm?2) and higher temperature (i.e., 60 °C) favored a pathway leading mainly to cyclohexanone. The guaiacol conversion routes were affected by temperature- and cathode potential-dependent surface coverage of adsorbed hydrogen radicals generated through electroreduction of protons.
- Wijaya, Yanuar Philip,Grossmann-Neuhaeusler, Tobias,Dhewangga Putra, Robertus Dhimas,Smith, Kevin J.,Kim, Chang Soo,Gyenge, El?d L.
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p. 629 - 639
(2020/01/21)
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- Selective Hydrodeoxygenation of Guaiacol to Cyclohexanol Catalyzed by Nanoporous Nickel
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Abstract: Cyclohexanol is an important feedstock in the chemical industry and the selective hydrodeoxygenation of lignin-derived guaiacol to cyclohexanol have gained increasing research attention in recent years. In this work, a series of nanoporous metal catalysts were employed for the hydrodeoxygenation of guaiacol and nanoporous Ni (NP-Ni) exhibited high catalytic performance for the preparation of cyclohexanol. With water as solvent, 100% conversion of guaiacol and over 90% selectivity to cyclohexanol were achieved at 180?°C and 2?MPa for 4?h. In order to further promote the stability of NP-Ni, induction melting, vacuum arc melting and mechanical alloying were separately employed for the preparation of NiAl precursor alloy. Mechanical alloying seemed to be an effective method for the alloying process and the as-prepared NP-Ni could keep almost stable after 10 times recycling. Furthermore, the reaction mechanism was investigated with NP-Ni for guaiacol hydrodeoxygenation. Scanning electron microscope (SEM), Brunauer–Emmett–Teller (BET) surface area analysis, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron micrographs (TEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) were employed for the characterization of NiAl alloy and the optimal preparation methods of NP-Ni were acquired according to the characterization results. Graphic Abstract: [Figure not available: see fulltext.].
- Lu, Jiqing,Liu, Xing,Yu, Guanqun,Lv, Jinkun,Rong, Zeming,Wang, Mei,Wang, Yue
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p. 837 - 848
(2019/11/03)
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- Ru subnanoparticles on N-doped carbon layer coated SBA-15 as efficient Catalysts for arene hydrogenation
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The N-doped carbon layer coated SBA-15 support has been accomplished via a pyrolysis process. The ultra-low loading Ru nanoparticles (ca. 0.1 wt.%) was incorporated into the support by impregnation and the sequential reduction. The images of HAADF-STEM revealed that the Ru particles with sub-1-nm size (0.2-0.7 nm) were uniformly dispersed on the support. The ultrafine Ru particles displayed the excellent activity for the hydrogenation of olefins, arenes, phenol derivatives and heteroarenes in aqueous phase. The aliphatic or alicyclic compounds were produced selectively without the hydrogenolysis of C–O and C–N bonds. The high turnover frequency (TOF) values can reach up to 10,000 h?1. Notably, the activity of these catalysts improved dramatically with decreasing the sizes of Ru particles. Meanwhile, the N-doped carbon layer coating endowed the high stability of the Ru catalysts and prevented the leaching of the Ru species owning to the strong interaction between doped-N atoms and the ultrafine Ru particles. Overall, this work provides a highly attractive strategy to construct the supported sub-1-nm Ru particles utilized for the aqueous hydrogenation.
- Qian, Wei,Lin, Lina,Qiao, Yunxiang,Zhao,Xu, Zichen,Gong, Honghui,Li,Chen,Huang, Rong,Hou, Zhenshan
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- Low temperature hydrodeoxygenation of guaiacol into cyclohexane over Ni/SiO2 catalyst combined with Hβ zeolite
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Hydrodeoxygenation (HDO) of guaiacol to cyclohexane, important for bio-oil upgrading, is usually performed at high reaction temperature (≥200 °C). In this work, low temperature transformation of guaiacol to cyclohexane was achieved at 140 °C over non-noble metal Ni/SiO2 and various zeolites. Among zeolites tested (HUSY, HMOR, Hβ, HZSM-5, SAPO-34), Hβ zeolite exhibited superior catalytic activity due to its appropriate pore structure and acid strength. The open pore with three-dimensional structure of Hβ facilitates the diffusion of guaiacol and intermediates. Meanwhile, weak acid strength of Hβ efficiently reduces the competitive adsorption of guaiacol, and then promotes the dehydration of intermediate 2-methoxycyclohexanol. Moreover, the catalytic performance in guaiacol HDO to cyclohexane is also closely related to Si/Al ratio of Hβ. Owing to its moderate acid density, the maximum yield of cyclohexane reaches 91.7% on Hβ(Si/Al = 50) combined with Ni/SiO2 at 140 °C, which is the lowest temperature ever reported over non-noble metal catalysts.
- Wang, Xun,Zhu, Shanhui,Wang, Sen,He, Yue,Liu, Yang,Wang, Jianguo,Fan, Weibin,Lv, Yongkang
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p. 3868 - 3876
(2019/02/12)
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- Ruthenium Catalysts on ZSM-5/MCM-41 Micro-Mesoporous Support for Hydrodeoxygenation of Guaiacol in the Presence of Water
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A ruthenium-containing catalyst on ZSM-5/MCM-41 micro-mesoporous aluminosilicate support was synthesized. The micro-mesoporous support and supported catalyst were characterized by low-temperature nitrogen desorption/adsorption, temperature-programmed ammonia desorption, transmission electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction with hydrogen, and energy-dispersive X-ray fluorescence analysis. Ru/ZSM-5/MCM-41 has high specific surface area (392 m2 g?1) and high acidity (1087 μmol g?1); the mean ruthenium particle size is 1.7 nm. The catalyst was studied in hydrodeoxygenation of a modelbio-oil compound, guaiacol, in the presence of water at a hydrogen pressure of 5 MPa and temperatures in the interval 130–290°C. The catalyst obtained exhibits high activity in guaiacol hydrodeoxygenation: The conversion was 90%, and the selectivity with respect to cycloalkanes was 64% in 3-h reaction performed at a hydrogen pressure of 5 MPa and a temperature of 230°C.
- Roldugina,Glotov,Isakov,Maksimov,Vinokurov,Karakhanov
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p. 1170 - 1178
(2019/10/22)
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- A Nanospherical Mesoporous Ruthenium-Containing Polymer as a Guaiacol Hydrogenation Catalyst
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Abstract: A hybrid catalyst is synthesized using ruthenium nanoparticles deposited on a nanospherical mesoporous polymer. Catalytic properties are studied in guaiacol hydrogenation at a temperature of 200–250°С and a hydrogen pressure of 5.0 MPa. Effect of solvent and catalytic additives on the reaction is investigated. It is shown that the synthesized catalyst exhibits the highest activity in guaiacol hydrodeoxygenation in the two-phase system water/n-dodecane and when the reaction is carried out in the presence of scandium triflate.
- Boronoev,Shakirov,Ignat’eva,Maximov,Karakhanov
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p. 1300 - 1306
(2020/01/02)
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- Demethoxylation of hydrogenated derivatives of guaiacol without external hydrogen over platinum catalyst
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Selective deoxygenation of 2-methoxycyclohexanone, one of the hydrogenated by-products in guaiacol hydrodeoxygenation, to phenol, cyclohexanone and cyclohexanol was investigated over carbon supported noble metal catalysts without external H2. Pt/C exhibited the best performance and the yield of target products reached 48% in water solvent at 493 K. This system can be applied to demethoxylation of 2-methoxycyclohexanol (49% yield). Demethoxylation of guaiacol is also possible under 0.1 MPa of H2 (46% yield). The yield of the target demethoxylation products was strongly dependent on the catalyst amount; too much catalyst decreased the yield due to the over-reaction, while the reaction stopped before total conversion of intermediates when the catalyst amount was too small. Fresh Pt/C catalyst has activity in hydrodeoxygenation of the target products and the reusability test showed deactivation of Pt/C during reaction, suggesting that deactivation at appropriate reaction progress controlled by catalyst amount is a key to good yield of the target products. In contrast to other noble metal catalysts, Pt/C has activity in both dehydrogenation of cyclohexane ring and hydrogenolysis of C–O bond, both of which contributed to the conversion of 2-methoxycyclohexanone to target demethoxylation products, according to the reactions of cyclohexanone and cyclohexanol as model substrates.
- Miyagawa, Akari,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
-
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- Fiber-supported Fe(iii) complex catalyst in spinning basket reactor for cleaner ring-opening of epoxides with alcohols
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Herein, a newly designed fiber-supported iron catalyst was successfully synthesized by rooting diamine ligands into the surface layer of commercially available polyacrylonitrile fiber and then utilizing the diamine groups to immobilize Fe(iii) ions for heterogeneous catalytic ring-opening reactions. The resulting materials were characterized and observed in detail by elemental analysis, mechanical properties, FTIR spectroscopy and morphology during both the preparation and the utilization processes. Moreover, the fiber catalyst was used in the spinning basket reactor-mediated ring-opening of various epoxides by a series of alcohols under mild reaction conditions, giving good to quantitative yields of the corresponding β-alkoxy alcohols. In addition, the fiber catalyst in the impellers of the agitation system was shown to be reusable multiple times without leaching of the Fe(iii) ions, and when stored on the shelf remained equally active for at least three months. Furthermore, the catalytic system was convenient and effective for scaling-up experiments and thereby has prospects in industrial applications.
- Shi, Xian-Lei,Sun, Benyu,Hu, Qianqian,Chen, Yongju,Duan, Peigao
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p. 3573 - 3582
(2019/07/09)
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- Ru/hydroxyapatite as a dual-functional catalyst for efficient transfer hydrogenolytic cleavage of aromatic ether bonds without additional bases
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Cleavage of aromatic ether bonds is a key step for lignin valorization, and the development of novel heterogeneous catalysts with high activity is crucial. Herein, bifunctional Ru/hydroxyapatite has been prepared via ion exchange and subsequent reduction. The obtained Ru/hydroxyapatite could efficiently catalyze the cleavage of various compounds containing aromatic ether bonds via transfer hydrogenolysis without additional bases. Systematic studies indicated that the basic nature of hydroxyapatite and electron-enriched Ru sites resulted in the high activity of the catalyst. A mechanism study revealed that the direct cleavage of aromatic ether bonds was the main reaction pathway.
- Hua, Manli,Song, Jinliang,Xie, Chao,Wu, Haoran,Hu, Yue,Huang, Xin,Han, Buxing
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p. 5073 - 5079
(2019/09/30)
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- Ru(III) complex anchored onto amino-functionalized MIL-101(Cr) framework via post-synthetic modification: an efficient heterogeneous catalyst for ring opening of epoxides
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In this work, the metallo Schiff base-functionalized metal–organic framework was prepared by post-synthetic method and used as an electron-deficient catalyst for the alcoholysis of epoxides. In this manner, the aminated MIL-101 was modified with 2-pyridine carboxaldehyde and then the prepared Schiff base reacted with RuCl3. This new catalyst, MIL-101–NH2–PC–Ru, was characterized by Fourier transform infrared, UV–Vis spectroscopic techniques, X-ray diffraction, BET, inductively coupled plasma atomic emission spectroscopy and field-emission scanning electron microscopy. In the presence of this heterogeneous catalyst, ring opening of epoxides was performed under mild condition to show the significant ability and successful applications of Lewis acid containing catalysts in corporation with metal–organic frameworks. The reusability of the catalyst was also investigated. No noticeable decrease in the catalytic activity was found after four consecutive times.
- Jafari, Aneseh Khalatbari,Kardanpour, Reihaneh,Tangestaninejad, Shahram,Mirkhani, Valiollah,Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Zadehahmadi, Farnaz
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p. 997 - 1006
(2018/05/23)
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- Guaiacol Hydrogenation in an Aqueous Medium in the Presence of a Palladium Catalyst Supported on a Mesoporous Dendrimer-Containing Polymer
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Guaiacol hydrogenation in an aqueous medium in the presence of a palladium catalyst supported on a mesoporous dendrimer-containing polymer and the effect of addition of sulfuric acid to the catalyst system have been studied. It has been found that the main hydrogenation product is 2-methoxycyclohexanol. After the addition of sulfuric acid to the catalyst system, the reaction mechanism significantly changes and cyclohexanol becomes the main hydrogenation product.
- Karakhanov,Boronoev,Filippova, T. Yu.,Maksimov
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p. 407 - 411
(2018/05/28)
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- Elucidating the reactivity of methoxyphenol positional isomers towards hydrogen-transfer reactions by ATR-IR spectroscopy of the liquid-solid interface of RANEY Ni
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In the valorisation of lignin, the application of catalytic hydrogen transfer reactions (e.g. in catalytic upstream biorefining or lignin-first biorefining) has brought a renewed interest in the fundamental understanding of hydrogen-transfer processes in the defunctionalisation of lignin-derived phenolics. In this report, we address fundamental questions underlining the distinct reactivity patterns of positional isomers of guaiacol towards H-transfer reactions in the presence of RANEY Ni and 2-PrOH (solvent and H-donor). We studied the relationship between reactivity patterns of 2-, 3- and 4-methoxyphenols and their interactions at the liquid-solid interface of RANEY Ni as probed by attenuated total reflection infrared (ATR-IR) spectroscopy. Regarding the reactivity patterns, 2-methoxyphenol or guaiacol is predominantly converted into cyclohexanol through a sequence of reactions including demethoxylation of 2-methoxyphenol to phenol followed by hydrogenation of phenol to cyclohexanol. By contrast, for the conversion of the two non-lignin related positional isomers, the corresponding 3- and 4-methoxycyclohexanols are the major reaction products. The ATR-IR spectra of the liquid-solid interface of RANEY Ni revealed that the adsorbed 2-methoxyphenol assumes a parallel orientation to the catalyst surface, which allows a strong interaction between the methoxy C-O bond and the surface. Conversely, the adsorption of 3- or 4-methoxyphenol leads to a tilted surface complex in which the methoxy C-O bond establishes no interaction with the catalyst. These observations are also corroborated by a smaller activation entropy found for the conversion of 2-methoxyphenol relative to those of the other two positional isomers.
- De Castro, Ilton Barros Daltro,Gra?a, Inês,Rodríguez-García, Laura,Kennema, Marco,Rinaldi, Roberto,Meemken, Fabian
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p. 3107 - 3114
(2018/06/29)
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- Effective hydrodeoxygenation of lignin-derived phenols using bimetallic RuRe catalysts: Effect of carbon supports
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We have previously shown that an activated carbon-supported ruthenium catalyst promoted with ReOx (RuRe/AC) is highly active for the hydrodeoxygenation (HDO) of lignin-derived phenols (e.g., guaiacol). In this work, we have investigated the effect of carbon supports on the structure and HDO activity of bimetallic RuRe particles using three different carbon supports, i.e., activated carbon (AC), carbon black (Vulcan carbon, VC), multi-walled carbon nanotube (MWCNT). The MWCNT- and VC-supported catalysts show remarkably enhanced activity and hydrocarbon selectivity for the HDO of a range of phenolic molecules (i.e., guaiacol, eugenol, benzyl phenyl ether) compared to RuRe/AC. STEM-EDS and XPS analyses reveal that bimetallic RuRe particles are more common than monometallic Ru or Re particles in the VC- and MWCNT-supported catalysts, and hexavalent rhenium species are more easily reduced to tetravalent rhenium during the HDO reactions in these catalysts, suggesting that Ru and Re in close proximity are required for the efficient hydrogenolysis of phenols. The formation of bimetallic particles on the AC surface is likely hindered by high microporosity and high surface oxygen functionalities, both of which restrict the mobility of Re and Ru for assembly.
- Jung, Kyung Bin,Lee, Jinho,Ha, Jeong-Myeong,Lee, Hyunjoo,Suh, Dong Jin,Jun, Chul-Ho,Jae, Jungho
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p. 191 - 199
(2017/09/06)
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- Ni/HZSM-5 catalyst preparation by deposition-precipitation. Part 2. Catalytic hydrodeoxygenation reactions of lignin model compounds in organic and aqueous systems
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Nickel metal supported on HZSM-5 (zeolite) is a promising catalyst for lignin depolymerization. In this work, the ability of catalysts prepared via deposition-precipitation (DP) to perform hydrodeoxygenation (HDO) on two lignin model compounds in organic and aqueous solvents was evaluated; guaiacol in dodecane and 2-phenoxy-1-phenylethanol (PPE) in aqueous solutions. All Ni/HZSM-5 catalysts were capable of guaiacol HDO into cyclohexane at 523 K. The role of the HZSM-5 acid sites was confirmed by comparison with Ni/SiO2 (inert support) which exhibited incomplete deoxygenation of guaiacol due to the inability to perform the cyclohexanol dehydration step. The catalyst prepared with 15 wt% Ni, a DP time of 16 h, and a calcination temperature of 673 K (Ni(15)/HZSM-5 DP16_Cal673), performed the guaiacol conversion with the greatest selectivity towards HDO products, with an intrinsic rate ratio (HDO rate to conversion rate) of 0.31, and 90% selectivity to cyclohexane. Catalytic activity and selectivity of Ni/HZSM-5 (15 wt%) in aqueous environments (water and 0.1 M NaOH solution) was confirmed using PPE reactions at 523 K. After 30 min reaction time in water, Ni/HZSM-5 exhibited ~100% conversion of PPE, and good yield of the desired products; ethylbenzene and phenol (~35% and 23% of initial carbon, respectively). Ni/HZSM-5 in NaOH solution resulted in significantly higher ring saturation compared to the Ni/HZSM-5 in water or the NaOH solution control.
- Barton,Carrier,Segura,Fierro,Park,Lamb,Escalona,Peretti
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p. 294 - 309
(2018/06/26)
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- Oxidoperoxidomolybdenum(VI) complexes with acylpyrazolonate ligands: Synthesis, structure and catalytic properties
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Oxidoperoxido-molybdenum(vi) complexes containing acylpyrazolonate ligands were obtained by reaction of [Mo(O)(O)2(H2O)n] with the corresponding acylpyrazolone compounds HQR. Complexes Ph4P[Mo(O)(O2)2(QR)] (R = neopentyl, 1; perfluoroethyl, 2; hexyl, 3; phenyl, 4; naphthyl, 5; methyl, 6; cyclohexyl, 7; ethylcyclopentyl, 8) were obtained if the reaction was carried out with one equivalent of HQR in the presence of Ph4PCl. Alternatively, neutral complexes [Mo(O)(O2)(QR)2] (R = neopentyl, 9; hexyl, 10; cyclohexyl, 11) were formed when two equivalents of HQR were used in the reaction. These complexes were isolated in good yields as yellow or yellow-orange crystalline solids and were spectroscopically (IR, 1H, 13C{1H} and 31P{1H} NMR), theoretically (DFT) and structurally characterised (X-ray for 1, 2, 9 and 10). Compounds 1 and 9 were selected to investigate their catalytic behaviour in epoxidation of selected alkenes and oxidation of selected sulphides, while 10 and 11 were tested as catalyst precursors in the deoxygenation of selected epoxide substrates to alkenes, using PPh3 as the oxygen-acceptor. Complexes Ph4P[Mo(O)(O2)2(QR)] were shown to be poor catalyst precursors in oxidation reactions, while the activity of [Mo(O)(O2)(QR)2] species is good in all the studied reactions and comparable to related oxidoperoxido-molybdenum(vi) complexes. Complex [Mo(O)2(QC6)2], 12, was obtained by treatment of 10 with one equivalent of PPh3, demonstrating that the first step in the epoxide deoxygenation mechanism was the oxygen atom transfer toward the phosphane.
- Begines, Emilio,Carrasco, Carlos J.,Montilla, Francisco,álvarez, Eleuterio,Marchetti, Fabio,Pettinari, Riccardo,Pettinari, Claudio,Galindo, Agustín
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p. 197 - 208
(2017/12/27)
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- Synthesis and structure of an air-stable bis(pentamethylcyclopentadienyl) zirconium pentafluorbezenesulfonate and its application in catalytic epoxide ring-opening reactions
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An air-stable mononuclear complex of bis(pentamethylcyclopentadienyl) zirconium pentafluorbezenesulfonate was successfully synthesized by treating C6F5SO3Ag with [(CH3)5Cp]2ZrCl2, which showed the cationic uninuclear structure of [{(CH3)5Cp}2Zr(CH3CN)2(H2O)][OSO2C6F5]2·CH3CN (1) confirmed by the X-ray analysis. Complex 1 was also characterized by other techniques and found to have the good nature of air-stability, water tolerance, thermally-stability and strong Lewis-acidity. Moreover, the complex showed high catalytic activity and recyclability in catalytic epoxide ring-opening reactions by amines or alcohols. This catalytic system affords a simple and efficient approach for synthesis of β-amino alcohols or β-alkoxy alcohols.
- Li, Ningbo,Wang, Lingxiao,Wang, Haojiang,Qiao, Jie,Zhao, Wenjie,Xu, Xinhua,Liang, Zhiwu
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p. 1033 - 1039
(2018/02/06)
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- Continuous-Flow Palladium-Catalyzed Synthesis of Cyclohexanones from Phenols using Sodium Formate as a Safe Hydrogen Source
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We report a procedure for the continuous-flow production of cyclohexanone from phenol on the basis of the use of sodium formate as a biomass-derived source of hydrogen and Pd/C as an easily accessible catalyst system. The reaction worked in water at pH 12.0 at 90 °C. By setting a packed reactor charged with the Pd/C catalyst (10 wt %) at a flow rate of 0.5 mL min?1, we achieved continuous-flow production of cyclohexanone in high yield with high selectivity and productivity.
- Valentini, Federica,Santillo, Niccolò,Petrucci, Chiara,Lanari, Daniela,Petricci, Elena,Taddei, Maurizio,Vaccaro, Luigi
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p. 1277 - 1281
(2018/02/23)
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- Zirconium triflate grafted on SBA-15 as a highly efficient solid acid catalyst for ring opening of epoxides by amines and alcohols
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Metal (Al, Ti, Zr) triflate grafted mesoporous SBA-15 (AlTf/S, TiTf/S, ZrTf/S) samples were synthesized as inexpensive solid acid materials by a simple one-pot-two-step synthesis methodology. These materials were characterized by X-ray diffraction, N2-sorption, thermogravimetric analysis, Fourier transform infrared spectroscopy (FT-IR), in-situ pyridine FT-IR spectroscopy, and elemental analysis. ZrTf/S was found to be a highly efficient and reusable solid acid catalyst for ring opening of epoxides with amines and alcohols and produced β-amino alcohols and β-alkoxy alcohols respectively under ambient reaction conditions. The ZrTf/S catalyst showed the highest activity, which was attributed to its high acidity compared with that of the Ti and Al containing samples.
- Tayade, Kamlesh N.,Wang, Lianyue,Shang, Sensen,Dai, Wen,Mishra, Manish,Gao, Shuang
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p. 758 - 766
(2017/04/24)
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- A method for synthesis of substituted cyclohexanol
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The invention discloses a substituted cyclohexanol synthesis method. The substituted cyclohexanol synthesis method comprises that a phenolic compound as a raw material undergoes a one-step reaction in the presence of an amorphous alloy as a catalyst in a water phase to produce substituted cyclohexanol. The substituted cyclohexanol synthesis method is free of an organic solvent, has environmental friendliness, realizes high activity and high selectivity conversion of a phenolic compound into substituted cyclohexanol, has low energy consumption, is convenient for operation and prevents carbon deposition-caused catalyst deactivation.
- -
-
Paragraph 0047; 0048
(2017/08/25)
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- Phosphate modified ceria as a Br?nsted acidic/redox multifunctional catalyst
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Deposition of trimethylphosphate onto ceria followed by thermal treatment resulted in the formation of surface phosphates with retention of the ceria fluorite structure. The structural and chemical properties of the phosphate-functionalized ceria were studied using 31P solid-state NMR, XPS, zeta titration, ammonia thermal desorption, pyridine adsorption, and model reactions. The introduction of phosphates generated Br?nsted acid sites and decreased the number of Lewis acid sites on the surface. The relative amount of Lewis and Br?nsted acids can be controlled by the amount of trimethylphosphate used in the synthesis. Upon deposition of Pd, the multifunctional material showed enhanced activity for the hydrogenolysis of eugenol and guaiacol compared to Pd on the unmodified ceria support. This was attributed to the cooperativity between the Lewis acid sites, which activate the substrate for dearomatization, and the redox/Br?nsted acid properties, which catalyze hydrogenolysis.
- Nelson, Nicholas C.,Wang, Zhuoran,Naik, Pranjali,Manzano, J. Sebastián,Pruski, Marek,Slowing, Igor I.
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supporting information
p. 4455 - 4466
(2017/03/09)
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- A biomass phenolic compound catalytic hydrogenation method of synthesizing cyclohexyl alcohol compound (by machine translation)
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The invention relates to a biomass phenolic compound catalytic hydrogenation method of synthesizing cyclohexyl alcohol compound. It in order to load the noble metal palladium titanium dioxide as catalyst, biomass phenolic compound by catalytic hydrogenation synthesis of cyclohexyl alcohol compound, the obtained cyclohexyl alcohol compound can be used as fuel additives or pharmaceutical chemical intermediate, improving the utilization rate of renewable sources of energy, to relieve the energy crisis and the increasing importance attached to the problem of environmental pollution, its catalyst has simple preparation process, green environmental protection, does not pollute the environment, suitable for popularization and application. (by machine translation)
- -
-
Paragraph 0014; 0015; 0016; 0017; 0018; 0019; 0020-0026
(2017/09/26)
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- Catalysis Meets Nonthermal Separation for the Production of (Alkyl)phenols and Hydrocarbons from Pyrolysis Oil
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A simple and efficient hydrodeoxygenation strategy is described to selectively generate and separate high-value alkylphenols from pyrolysis bio-oil, produced directly from lignocellulosic biomass. The overall process is efficient and only requires low pressures of hydrogen gas (5 bar). Initially, an investigation using model compounds indicates that MoCx/C is a promising catalyst for targeted hydrodeoxygenation, enabling selective retention of the desired Ar?OH substituents. By applying this procedure to pyrolysis bio-oil, the primary products (phenol/4-alkylphenols and hydrocarbons) are easily separable from each other by short-path column chromatography, serving as potential valuable feedstocks for industry. The strategy requires no prior fractionation of the lignocellulosic biomass, no further synthetic steps, and no input of additional (e.g., petrochemical) platform molecules.
- Cao, Zhengwen,Engelhardt, Jan,Dierks, Michael,Clough, Matthew T.,Wang, Guang-Hui,Heracleous, Eleni,Lappas, Angelos,Rinaldi, Roberto,Schüth, Ferdi
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supporting information
p. 2334 - 2339
(2017/02/23)
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- METHOD FOR PRODUCING AN AROMA SUBSTANCE
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A method of preparing a compound of formula (IV) where R1 is alkyl of 1 to 4 carbon atoms, comprises reacting cyclohexene with hydrogen peroxide and an alcohol R1OH in the presence of a catalyst comprising a zeolite of framework structure MWW, wherein the framework of the zeolite comprises silicon, titanium, boron, oxygen and hydrogen.
- -
-
Paragraph 0288
(2017/10/17)
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- Introduction of an effective and economical heterogeneous ruthenium catalyst for regioselective ring-opening of epoxides and the friedel-crafts alkylation reaction of indoles and pyrroles
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Background: Metal organic frameworks square measure crystalline materials with fascinating chemical and physical attributes that include metal ions or clusters and multidentate organic particles. MOFs acquire the expected traits to be employed in classical applications similar to heterogeneous catalysis and storage and separation of gases and different Compounds. Post-synthetic modification (PSM) is an associate replacement method to prepare functionalized MOFs. Methods: The IRMOF-3-PI-RuCl3 was prepared by refluxing a combination of IRMOF-3-PI, [H(DMSO)2][RuCl4(DMSO)2] and ethanol. The amount of ruthenium metal in catalyst was found to be 2.35 w% based on ICP analysis. To perform the ring opening reaction, a solution of styrene oxide, indole, pyrole or alcohol nucleophile, in methanol, IRMOF-3-PI-RuCl3 was added. After completion of the reaction, the catalyst was precipitated. Results: A MOF-supported metal catalyst (IRMOF-3-PI-RuCl3) was designed and synthesized by postsynthetic method. The BET surface area of the final catalyst was slightly reduced as determined by N2 sorption experiments. The results showed that the provided catalyst has a high potential for the ring opening of epoxides with alcohols, indoles and pyrroles under gentle conditions. Conclusion: In summary, a simple, rapid, economical and an effective route for the alcoholysis of epoxides and therefore the Friedel-Crafts alkylation of indoles and pyrroles via an basically regioselective ring opening of epoxides with aliphatic and aromatic amines using IRMOF-3-PI-RuCl3 with cage type poriferous structure as heterogeneous catalysts, has been established. This methodology is very regioselective in numerous instances that give the products with high yield for e.g. in aromatic and aliphatic amines. Ease of separation and straightforward workup are among other advantages of this catalyst.
- Tabatabaeian, Khalil,Zanjanchi, Mohammad Ali,Mahmoodi, Nosrat O.,Eftekhari, Tooraj
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p. 207 - 217
(2017/06/21)
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- METHOD FOR THE PREPARATION OF 2-ALKOXY CYCLOHEXANOL
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A method of preparing 2-alkoxycyclohexanol, a mixture comprising 2-alkoxycyclohexanol obtained via said method, and the use of said mixture for preparing 4-hydroxy-3-alkoxy-benzaldehyde.
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-
Paragraph 0305; 0306; 0307; 0308
(2017/10/10)
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- Reductive fractionation of woody biomass into lignin monomers and cellulose by tandem metal triflate and Pd/C catalysis
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A catalytic process for the upgrading of woody biomass into mono-aromatics, hemi-cellulose sugars and a solid cellulose-rich carbohydrate residue is presented. Lignin fragments are extracted from the lignocellulosic matrix by cleavage of ester and ether linkages between lignin and carbohydrates by the catalytic action of homogeneous Lewis acid metal triflates in methanol. The released lignin fragments are converted into lignin monomers by the combined catalytic action of Pd/C and metal triflates in hydrogen. The mechanism of ether bond cleavage is investigated by lignin dimer models (benzyl phenyl ether, guaiacylglycerol-β-guaiacyl ether, 2-phenylethyl phenyl ether and 2-phenoxy-1-phenylethanol). Metal triflates are involved in cleaving not only ester and ether linkages between lignin and the carbohydrates but also β-O-4 ether linkages within the aromatic lignin structure. Metal triflates are more active for β-O-4 ether bond cleavage than Pd/C. On the other hand, Pd/C is required for cleaving α-O-4, 4-O-5 and β-β linkages. Insight into the synergy between Pd/C and metal triflates allowed optimizing the reductive fractionation process. Under optimized conditions, 55 wt% mono-aromatics-mainly alkylmethoxyphenols-can be obtained from the lignin fraction (23.8 wt%) of birch wood in a reaction system comprising birch wood, methanol and small amounts of Pd/C and Al(III)-triflate as catalysts. The promise of scale-up of this process is demonstrated.
- Huang, Xiaoming,Morales Gonzalez, Olivia M.,Zhu, Jiadong,Korányi, Tamás I.,Boot, Michael D.,Hensen, Emiel J. M.
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p. 175 - 187
(2017/01/24)
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- Influence of functionalization of terephthalate linker on the catalytic activity of UiO-66 for epoxide ring opening
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A series of five isostructural zirconium terephthalate UiO-66 metal organic frameworks bearing different functional groups on the terephthalate linker (UiO-66-X; X = H, NH2, NO2, Br, Cl,) have been successfully prepared and characterized. UiO-66-X materials were evaluated as heterogeneous catalysts for the epoxide ring opening of styrene oxide by methanol, observing an increase in the initial reaction rate from UiO-66-H to UiO-66-Br, over one order of magnitude. The reactivity order, however, does not follow a linear relationship between the Hammett constant value of the substituent and the initial reaction rate. UiO-66-Br exhibits a wide scope, its activity depending on the structure of epoxide and nucleophile. The absence of Zr leaching to the solution together with the preservation of the UiO-66-X crystallinity confirms the stability of the framework under the reaction conditions. Nevertheless, UiO-66 undergoes a progressive deactivation upon reuse that was attributed to a strong adsorption of the reaction product.
- Blandez, Juan F.,Santiago-Portillo, Andrea,Navalón, Sergio,Giménez-Marqués, Mónica,álvaro, Mercedes,Horcajada, Patricia,García, Hermenegildo
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p. 332 - 339
(2016/12/09)
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- Enhancement of CO2 Adsorption and Catalytic Properties by Fe-Doping of [Ga2(OH)2(L)] (H4L = Biphenyl-3,3′,5,5′-tetracarboxylic Acid), MFM-300(Ga2)
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Metal-organic frameworks (MOFs) are usually synthesized using a single type of metal ion, and MOFs containing mixtures of different metal ions are of great interest and represent a methodology to enhance and tune materials properties. We report the synthesis of [Ga2(OH)2(L)] (H4L = biphenyl-3,3′,5,5′-tetracarboxylic acid), designated as MFM-300(Ga2), (MFM = Manchester Framework Material replacing NOTT designation), by solvothermal reaction of Ga(NO3)3 and H4L in a mixture of DMF, THF, and water containing HCl for 3 days. MFM-300(Ga2) crystallizes in the tetragonal space group I4122, a = b = 15.0174(7) ? and c = 11.9111(11) ? and is isostructural with the Al(III) analogue MFM-300(Al2) with pores decorated with -OH groups bridging Ga(III) centers. The isostructural Fe-doped material [Ga1.87Fe0.13(OH)2(L)], MFM-300(Ga1.87Fe0.13), can be prepared under similar conditions to MFM-300(Ga2) via reaction of a homogeneous mixture of Fe(NO3)3 and Ga(NO3)3 with biphenyl-3,3′,5,5′-tetracarboxylic acid. An Fe(III)-based material [Fe3O1.5(OH)(HL)(L)0.5(H2O)3.5], MFM-310(Fe), was synthesized with Fe(NO3)3 and the same ligand via hydrothermal methods. [MFM-310(Fe)] crystallizes in the orthorhombic space group Pmn21 with a = 10.560(4) ?, b = 19.451(8) ?, and c = 11.773(5) ? and incorporates μ3-oxo-centered trinuclear iron cluster nodes connected by ligands to give a 3D nonporous framework that has a different structure to the MFM-300 series. Thus, Fe-doping can be used to monitor the effects of the heteroatom center within a parent Ga(III) framework without the requirement of synthesizing the isostructural Fe(III) analogue [Fe2(OH)2(L)], MFM-300(Fe2), which we have thus far been unable to prepare. Fe-doping of MFM-300(Ga2) affords positive effects on gas adsorption capacities, particularly for CO2 adsorption, whereby MFM-300(Ga1.87Fe0.13) shows a 49% enhancement of CO2 adsorption capacity in comparison to the homometallic parent material. We thus report herein the highest CO2 uptake (2.86 mmol g-1 at 273 K at 1 bar) for a Ga-based MOF. The single-crystal X-ray structures of MFM-300(Ga2)-solv, MFM-300(Ga2), MFM-300(Ga2)·2.35CO2, MFM-300(Ga1.87Fe0.13)-solv, MFM-300(Ga1.87Fe0.13), and MFM-300(Ga1.87Fe0.13)·2.0CO2 have been determined. Most notably, in situ single-crystal diffraction studies of gas-loaded materials have revealed that Fe-doping has a significant impact on the molecular details for CO2 binding in the pore, with the bridging M-OH hydroxyl groups being preferred binding sites for CO2 within these framework materials. In situ synchrotron IR spectroscopic measurements on CO2 binding with respect to the -OH groups in the pore are consistent with the above structural analyses. In addition, we found that, compared to MFM-300(Ga2), Fe-doped MFM-300(Ga1.87Fe0.13) shows improved catalytic properties for the ring-opening reaction of styrene oxide, but similar activity for the room-temperature acetylation of benzaldehyde by methanol. The role of Fe-doping in these systems is discussed as a mechanism for enhancing porosity and the structural integrity of the parent material.
- Krap, Cristina P.,Newby, Ruth,Dhakshinamoorthy, Amarajothi,García, Hermenegildo,Cebula, Izabela,Easun, Timothy L.,Savage, Mathew,Eyley, Jennifer E.,Gao, Shan,Blake, Alexander J.,Lewis, William,Beton, Peter H.,Warren, Mark R.,Allan, David R.,Frogley, Mark D.,Tang, Chiu C.,Cinque, Gianfelice,Yang, Sihai,Schr?der, Martin
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p. 1076 - 1088
(2016/02/09)
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- Synthesis, structure and multifunctional catalytic properties of a Cu(i)-coordination polymer with outer-hanging CuBr2
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A 1D Cu(i)-coordination polymer [(CuL1)(CuBr2), 1] carrying external copper bromide moieties was synthesized. The outer-hanging [CuBr2]- moiety is attached to the 1D Cu(i)-CP backbone via a Cu?Cu bonding interaction, which makes it look like a coordination polymer supported CuBr2 species. 1 exhibits excellent multifunctional catalytic activity for phenol acetylation, A3-coupling (aldehyde-alkyne-amine) and styrene oxide methanolysis reactions. Its heterogeneous catalytic nature was confirmed by solution leaching experiment and it can be reused without significant loss of its catalytic activity and selectivity for the above reactions.
- Zhu, Neng-Xiu,Zhao, Chao-Wei,Yang, Jing,Wang, Xue-Ru,Ma, Jian-Ping,Dong, Yu-Bin
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p. 108645 - 108653
(2016/11/30)
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- Facile and selective hydrogenolysis of β-O-4 linkages in lignin catalyzed by Pd-Ni bimetallic nanoparticles supported on ZrO2
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The β-O-4 linkage in lignin can be selectively cleaved by Pd-Ni bimetallic nanoparticles supported on ZrO2 using hydrogen gas as the hydrogen donor under ambient pressure and neutral conditions. Conspicuous enhancement in activity is observed compared with single nickel and palladium catalysts based on the results of experiments and characterization. Moreover, hydrogenation of the produced phenols is tuned by adjusting the amount of NaBH4. The catalyst can be reused over ten times in the model reaction and over five times in the hydrogenolysis of lignin without an obvious change in activity and selectivity.
- Zhang, Jia-Wei,Cai, Yao,Lu, Guo-Ping,Cai, Chun
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p. 6229 - 6235
(2016/12/03)
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- Hydrodeoxygenation of guaiacol over Ni/carbon catalysts: Effect of the support and Ni loading
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Commercial carbon nanotubes (CNT), oxidized CNT (CNTox) and activated carbon (AC) were used as supports to prepare Ni/C catalysts with a nominal loading of 15 wt%. In addition, xNi/CNT catalysts with loadings of x: 10, 12, 15, 17, 20 wt% were prepared. The catalysts were characterized by N2 physisorption, temperature-programmed decomposition (TPD), potentiometric titration, H2-temperature programmed reduction (TPR), CO chemisorption and X-ray photoelectron spectroscopy (XPS). The catalysts were evaluated for the conversion of guaiacol at 573 K and 5 MPa H2 pressure for 4 h in a batch reactor. The activity of the xNi/CNT catalysts was related to Ni dispersion, while their selectivity was similar and favored the formation of hydrogenation products. The activity of 15Ni/CNT catalyst was higher than those of 15Ni/CNTox and 15Ni/AC catalysts. The higher activity of the 15Ni/CNT catalyst compared to 15Ni/AC catalyst was possibly due to their different morphologies, while the lower activity of the 15Ni/CNTox catalyst was attributed to the limiting effect of surface oxygen groups on the support. In addition, the higher acidity of the 15Ni/CNTox catalyst enhanced its hydrogenolysis and deoxygenation capacities.
- Dongil,Ghampson,García,Fierro,Escalona
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p. 2611 - 2623
(2016/01/15)
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