- Synthesis of well-defined yttrium-based Lewis acids by capturing a reaction intermediate and catalytic application for cycloaddition of CO2 to epoxides under atmospheric pressure
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Despite widespread use of yttrium halide complexes as powerful Lewis acids in catalysis, no strategies have yet been developed to prepare well-defined heterogeneous systems. Herein, we show that by applying the methodology of surface organometallic chemistry (SOMC), a readily available intermediate of the mechanism of the cycloaddition of CO2 to epoxides catalyzed by YCl3/TBAB (TBAB: tetrabutylammonium bromide) can be grafted on silica resulting in a well-defined complex [(SiO-)YCl(-OCH(CH3)CH2Cl)]. The complex was thoroughly characterized by means of elemental analysis, FT-IR, solid state (SS) NMR, XPS and XANES techniques. The thus-prepared surface complex serves as heterogeneous Lewis acid for the cycloaddition of CO2 to several epoxides under atmospheric pressure performing as a simple but efficient and recyclable material. Remarkably, the isolated complex prepared on highly dehydroxylated silica performed as the most efficient compound. Additional catalytic studies show that the yttrium complexes prepared in this study have the potential to be employed also as versatile Lewis acid catalyst for 5-hydroxymethyl furfural (HMF) reductive etherification. DFT calculations were carried out to investigate the possible grafting pathways and the mechanistic pathways of CO2-epoxide cycloaddition catalyzed by different surface model complexes.
- Sodpiban, Ounjit,Del Gobbo, Silvano,Barman, Samir,Aomchad, Vatcharaporn,Kidkhunthod, Pinit,Ould-Chikh, Samy,Poater, Albert,D'Elia, Valerio,Basset, Jean-Marie
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- Sustainable hydrothermal self-assembly of hafnium-lignosulfonate nanohybrids for highly efficient reductive upgrading of 5-hydroxymethylfurfural
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The research for highly selective catalytic transfer hydrogenation (CTH) of 5-hydroxymethylfurfural (5-HMF) into 2,5-bis(hydroxymethyl)furan (BHMF) is an extremely important pathway for biomass valorization. Herein, we use lignosulfonate, a waste by-product from the paper industry, as a building block to coordinate with different metal ions (Hf4+, Zr4+, Fe3+, Al3+, Zn2+) and thus a series of inorganic-biopolymer hybrids (M-LigS) were prepared by a hydrothermal self-assembly method. The resulting Hf-LigS hybrid with strong Lewis acid-base couple sites and moderate Br?nsted acidic sites from the inherent sulfonic groups in LigS exhibited the best catalytic activity for CTH of 5-HMF with 2-propanol (2-PrOH) in high yields (90%) under mild reaction conditions (100 °C in 2 h). This robust bifunctional acid-base Hf-LigS is also demonstrated to be effective in one-step reductive etherification of 5-HMF to 5-[(1-methylethoxy)methyl]-2-furanmethanol (MEFA), a potential biomass-derived fuel additive, with 95% yield. Kinetic studies revealed that the activation energy for CTH of 5-HMF was 62.25 kJ mol-1, accounting for the high reaction rate. Isotopic labelling experiments demonstrated that intermolecular hydrogen transfer from the α-C of 2-PrOH to the α-C of 5-HMF was the dominant reaction pathway and the direct hydride transfer on acid-base sites was the rate-determining step. Due to the strong interactions between Hf4+ and phenolic hydroxyl groups, Hf-LigS was highly stable and could be reused without a significant decline in activity.
- Zhou, Shenghui,Dai, Fanglin,Chen, Yian,Dang, Chao,Zhang, Cunzhi,Liu, Detao,Qi, Haisong
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- Role of lewis and Br?nsted acidity in metal chloride catalysis in organic media: Reductive etherification of furanics
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Metal chlorides are demonstrated to behave as bifunctional acid catalysts in organic media in the one-pot reductive etherification of 5-hydroxymethylfurfural (HMF) in 2-propanol toward production of biodiesel. Two competing reaction pathways, direct etherification to 5-(isopropoxymethyl)furfural and reductive etherification to 2,5-bis-(isopropoxymethyl)furan, are proposed with the selectivity depending on the metal ion. Furfural and furfuryl alcohol are used as model compounds to investigate each pathway individually. The roles of Lewis/Br?nsted acidity of metal chlorides solution are elucidated by kinetic studies in conjunction with salt speciation using electrospray soft ionization mass spectrometer. Br?nsted acidic species, generated from alcoholysis of the metal chlorides, are the predominant catalytically active species in etherification. On the other hand, partially hydrolyzed metal cations produced by alcoholysis/hydrolysis are responsible Lewis acid centers for furfural reduction to furfuryl alcohol. Isotopic labeling experiments, in combination with GCMS and 1H NMR analysis, reveal an intermolecular hydrogen transfer from the a-C of 2-propanol to the a-C of furfural as the rate-limiting step of furfural hydrogenation.
- Nguyen, Hannah,Xiao, Nicholas,Daniels, Sean,Marcella, Nicholas,Timoshenko, Janis,Frenkel, Anatoly,Vlachos, Dionisios G.
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- Assembly of Zr-based coordination polymer over USY zeolite as a highly efficient and robust acid catalyst for one-pot transformation of fructose into 2,5-bis(isopropoxymethyl)furan
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It is highly desirable but challenging to develop a one-pot process for the transformation of fructose into 2,5-bis(isopropoxymethyl)furan (BPMF), a promising biofuel component, because a cascade sequence involving dehydration, reduction, and etherification requires multifunctional acid catalysts. Herein, we propose a facile and firm assembly of Zr/2-methylimidazole (2-MeIM) coordination polymer over USY zeolite (USY?ZrCP) through N-Al bonds formed by the condensation of 2-MeIM and the hydroxyls on USY surface at room temperature. USY?ZrCP possesses an abundance of strong Lewis acid sites with suitable amount of Bronsted acid sites, which are mainly attributed to the highly dispersed Zr(IV) species and the hydroxyls over USY?ZrCP, respectively. Unexpectedly, USY?ZrCP could offer BPMF yield up to 82.6% from fructose in isopropanol by the integration of dehydration, Meerwein–Ponndorf–Verley reduction and etherification in a one-pot strategy. This work proposes a novel approach to prepare highly efficient and robust solid acid catalyst for the catalytic valorization of biomass-derived carbohydrates and their derivatives.
- Lei, Tingzhou,Lin, Lu,Liu, Huai,Liu, Shijie,Liu, Yiqiang,Sun, Yong,Tang, Xing,Wang, Ting,Wei, Junnan,Zeng, Xianhai
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- The effect of oxide acidity on HMF etherification
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The liquid-phase (69 bar) reaction of 5-hydroxymethylfurfural (HMF) with 2-propanol for production of furanyl ethers was studied at 413 and 453 K over a series of oxide catalysts, including γ-Al2O3, ZrO2, TiO2, Al2O3/SBA-15, ZrO 2/SBA-15, TiO2/SBA-15, H-BEA, and Sn-BEA. The acidity of each of the catalysts was first characterized for Bronsted sites using TPD-TGA of 2-propanamine and for Lewis sites using TPD-TGA of 1-propanol. Catalysts with strong Bronsted acidity (H-BEA and Al2O 3/SBA-15) formed 5-[(1-methylethoxy)methyl]furfural with high selectivities, while materials with Lewis acidity (γ-Al2O 3, ZrO2, TiO2, and Sn-BEA) or weak Bronsted acidity (ZrO2/SBA-15 and TiO2/SBA-15) were active for transfer hydrogenation from the alcohol to HMF to produce 2,5-bis(hydroxymethyl)furan, with subsequent reactions to the mono- or di-ethers. Each of the catalysts was stable under the flow-reactor conditions but the selectivities varied with the particular oxide being investigated. the Partner Organisations 2014.
- Luo, Jing,Yu, Jingye,Gorte, Raymond J.,Mahmoud, Eyas,Vlachos, Dionisios G.,Smith, Michael A.
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- Direct Visualization of Substitutional Li Doping in Supported Pt Nanoparticles and Their Ultra-selective Catalytic Hydrogenation Performance
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It has only recently been established that doping light elements (lithium, boron, and carbon) into supported transition metals can fill interstitial sites, which can be observed by the expanded unit cell. As an example, interstitial lithium (intLi) can block H filling octahedral interstices of palladium metal lattice, which improves partial hydrogenation of alkynes to alkenes under hydrogen. In contrast, herein, we report intLi is not found in the case of Pt/C. Instead, we observe for the first time a direct ‘substitution’ of Pt with substitutional lithium (subLi) in alternating atomic columns using scanning transmission electron microscopy-annular dark field (STEM-ADF). This ordered substitutional doping results in a contraction of the unit cell as shown by high-quality synchrotron X-ray diffraction (SXRD). The electron donation of d-band of Pt without higher orbital hybridizations by subLi offers an alternative way for ultra-selectivity in catalytic hydrogenation of carbonyl compounds by suppressing the facile CO bond breakage that would form alcohols.
- Chen, Tianyi,Foo, Christopher,Zheng, Jianwei J. W.,Fang, Huihuang,Nellist, Peter,Tsang, Shik Chi Edman
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supporting information
p. 12041 - 12046
(2021/07/14)
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- Copper-zinc alloy nanopowder: A robust precious-metal-free catalyst for the conversion of 5-hydroxymethylfurfural
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Noble-metal-free copper-zinc nanoalloy (2. It is also possible to convert 10 wt % HMF solutions in CPME, with an excellent DMF yield of 90 %. Milder temperatures favor selective (95 %) formation of 2,5-furandimethanol (FDM). The one-pot conversion of fructose to valuable furan-ethers was also explored. Recycling experiments for DMF production show remarkable catalyst stability. Transmission electron microscopy (TEM) characterization provides more insight into morphological changes of this intriguing class of materials during catalysis.
- Bottari, Giovanni,Kumalaputri, Angela J.,Krawczyk, Krzysztof K.,Feringa, Ben L.,Heeres, Hero J.,Barta, Katalin
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p. 1323 - 1327
(2015/05/05)
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- Cascade of liquid-phase catalytic transfer hydrogenation and etherification of 5-hydroxymethylfurfural to potential biodiesel components over Lewis acid zeolites
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We report a one-step process for the production of diesel fuel from biomass-derived 5-hydroxymethylfurfural (HMF). The reaction proceeds through the sequential transfer hydrogenation and etherification of HMF to 2,5-bis(alkoxymethyl)furan, a potential biodiesel additive, catalyzed by a Lewis acid zeolite, such as Sn-Beta or Zr-Beta. An alcohol is used as a hydrogen donor and as a reactant in etherification. This cascade reaction can selectively produce high yields of the biodiesel additive (>80 % yield) from HMF with the Sn-Beta catalyst and secondary alcohols, such as 2-propanol and 2-butanol. Diesel addiction: Biomass-derived 5-hydroxymethylfurfural (HMF) is converted to 2,5-bis(alkoxymethyl)furan, a potential biodiesel additive, through sequential transfer hydrogenation and etherification reactions catalyzed by a Lewis acid zeolite, such as Sn-Beta or Zr-Beta. Sn-Beta selectively produces high yields of the biodiesel additive (>80 % yield) with secondary alcohols, such as 2-propanol and 2-butanol, as hydrogen donors and as etherification agents. Copyright
- Jae, Jungho,Mahmoud, Eyas,Lobo, Raul F.,Vlachos, Dionisios G.
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p. 508 - 513
(2014/03/21)
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- Ether formation in the hydrogenolysis of hydroxymethylfurfural over palladium catalysts in alcoholic solution
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5-Hydroxymethylfurfural, a product from renewable feedstock, was subjected to hydrogenolysis over palladium catalysts in 1-propanol aiming at the synthesis of 2,5-dimethylfuran, a potential transportation fuel enhancer. Intermediates are 5-hydroxymethyl-2-(propyloxymethyl)furan, formed with high selectivity, and 5-methyl-2-(propyloxymethyl)furan. Acetals are assumed to be initially formed. Acetalisation and hydrogenolysis are catalysed by traces of a Bronsted acid. Important variables are the palladium support and the solvent. In 2-propanol also ether formation takes place. In 1,4-dioxane mainly 2,5-bis(hydroxymethyl)furan is formed, in water ring opening becomes a major reaction. The formation of some side-products is discussed.
- Luijkx, Gerard C.A.,Huck, Nina P.M.,Van Rantwijk, Fred,Maat, Leendert,Van Bekkum, Herman
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experimental part
p. 1037 - 1044
(2010/10/03)
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