- Catalytic Transfer Hydrogenation of Ethyl Levulinate to γ-Valerolactone Over Ni Supported on Equilibrium Fluid-Catalytic-Cracking Catalysts
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Nickel supported on equilibrium fluid-catalytic-cracking catalysts (Ni/E-cats) were prepared by a simple grinding-pyrolysis method and employed for the transfer hydrogenation of ethyl levulinate (EL) to γ-valerolactone (GVL). 96.2% selectivity of GVL and 90.3% conversion of EL were obtained at 180?°C for 6?h over 30-Ni/E-cat. Through XRD, N2 adsorption–desorption, NH3-TPD and SEM analysis, the high activity of the 30-Ni/E-cat catalyst was attributed to its dispersed Ni metal active centers and available acidic sites. Catalytic probe test revealed that metal and acid sites of Ni/E-cat played a synergistic catalytic role in the synthesis of GVL in 2-propanol, where Ni metal sites contribute to the hydrogenation of ketone group in EL, and acid sites of E-cat promoted the lactonization of intermediate ethyl- or isopropyl 4-hydroxyvalerate. Two reaction pathways and synergistic mechanism were proposed in this catalytic system. Moreover, Ni/E-cat catalyst exhibited good stability up to four cycles without obvious loss of catalytic activity. Graphic Abstract: [Figure not available: see fulltext.]
- Chen, Han,Xu, Qiong,Li, Hui,Liu, Jian,Liu, Xianxiang,Huang, Geng,Yin, Dulin
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p. 538 - 547
(2020/07/30)
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- Ammonia borane enabled upgrading of biomass derivatives at room temperature
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Simplifying biomass conversion to valuable products with high efficiency is pivotal for the sustainable development of society. Herein, an efficient catalyst-free system using ammonia borane (AB) as the hydrogen donor is described, which enables controllable reaction selectivity towards four value-added products in excellent yield (82-100%) under very mild conditions. In particular, the system is uniquely efficient to produce γ-valerolactone (GVL) at room temperature. Combined in situ NMR and computational studies elucidate the hydrogen transfer mechanism of AB in methanol, the novel pathway of GVL formation from levulinate in water, and a competitive mechanism between reduction and reductive amination in the same system. Moreover, carbohydrates are converted directly into GVL in good yield, using a one-pot, two-step strategy. Products of a rather broad scope are prepared within a short reaction time of 30 min by using this catalyst-free strategy in methanol at room temperature. This journal is
- Meier, Sebastian,Riisager, Anders,Yang, Song,Zhao, Wenfeng
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supporting information
p. 5972 - 5977
(2020/11/03)
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- A Diaminopropane Diolefin Ru(0) Complex Catalyzes Hydrogenation and Dehydrogenation Reactions
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New ruthenium (0) complexes with a cooperative diolefin diaminopropane (DAP) or the dehydrogenated iminopropenamide ligand (IPA) were synthesized for comparison with their diaminoethane (DAE)/ diazadiene (DAD) ruthenium analogues. These DAP/IPA complexes are efficient catalysts in dehydrogenation reactions of alkaline aqueous methanol which proceeds under mild conditions (T=70 °C) and of higher alcohols, forming the corresponding carbonate and carboxylates, respectively. The scope of the reaction includes an example of a 1,2-diol as model for biomass derived alcohols. Their catalytic applications are extended to the atom-efficient dehydrogenative coupling of alcohols and amines to amides. The reaction proceeds without any additives and is applicable to the synthesis of formamides from methanol. Moreover, DAP/IPA complexes catalyze the hydrogenation of a series of esters, lactone, ketone, activated olefin, aldehyde and imine substrates. The diaminopropane Ru catalyst exhibits higher activity compared to the dehydrogenated β-ketiminate (IPA) and previously studied DAD/DAE based catalysts. We present studies on their stoichiometric reactivity with relevance to their possible catalytic mechanisms and the isolation and full characterization of key reaction intermediates.
- Casas, Fernando,Trincado, Monica,Rodriguez-Lugo, Rafael,Baneerje, Dipshikha,Grützmacher, Hansj?rg
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p. 5241 - 5251
(2019/11/16)
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- Efficient catalytic hydrogenation of alkyl levulinates to γ-valerolactone
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Efficient hydrogenations of neat alkyl levulinates to γ-valerolactone were achieved with low catalyst loadings of either PNP Ru or Ir complexes, respectively, in the presence of a small amount of a base at low temperature and H2 pressure. Quantitative conversions and TONs reaching 9300 were achieved. Furthermore, we demonstrate the feasibility of the system to perform several cycles. Finally, deuterium labelling and NMR studies provide insight into the reaction mechanism.
- Padilla, Rosa,J?rgensen, Mike S. B.,Paix?o, Márcio W.,Nielsen, Martin
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supporting information
p. 5195 - 5200
(2019/10/11)
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- Continuous Hydrogenation of Ethyl Levulinate to 1,4-Pentanediol over 2.8Cu-3.5Fe/SBA-15 Catalyst at Low Loading: The Effect of Fe Doping
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Bimetallic Cu–Fe catalysts with low loading were prepared for hydrogenation of ethyl levulinate (EL) to 1,4-pentanediol (1,4-PDO). Among them, 2.8Cu-3.5Fe/SBA-15 (Cu/Fe molar ratio of 1:1.5) performed best, capable of converting EL to the key intermediate γ-valerolactone (GVL) at 140 °C with 97 % yield. It can also be used to hydrogenate GVL to 1,4-PDO with 92.6 % selectivity or convert EL to 1,4-PDO in one pot. The high activity of the catalyst at such a low loading was attributed to the highly dispersed metal species and the Fe doping effect. Various characterization methods indicated that Fe acted as both structural and electronic modifier to promote the chemical properties of the Cu species. Besides, the incorporation of Fe provided abundant Lewis acid sites and accelerated the reaction process. CuFeO2 was detected by energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and XRD. On the basis of a combination of characterization and reaction kinetics, synergistic catalysis by Cu0 and CuFeO2 is considered to be responsible for the excellent performance of the Cu–Fe catalysts.
- Deng, Tianyu,Yan, Long,Li, Xinglong,Fu, Yao
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p. 3837 - 3848
(2019/08/07)
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- Supported cobalt catalysts for the selective hydrogenation of ethyl levulinate to various chemicals
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A highly active and selective cobalt catalyst was developed for the hydrogenation of biomass-derived ethyl levulinate (EL) to γ-valerolactone (GVL), ethyl 4-hydroxypentanoate (EHP), 1,4-pentanediol (1,4-PDO) and 2-methyltetrahydrofuran (2-MTHF), which are considered to be value-added chemicals and important biofuels. The effects of reaction time, reaction temperature, catalyst amount and solvent on its catalytic performance were investigated. In addition, the reaction pathway was studied as well. It was found that the selectivity of GVL, 1,4-PDO and 2-MTHF on Co/ZrO2 can be easily tuned by changing reaction conditions, and can reach as high as 94%, 78% and 77%, respectively. The product selectivity is also significantly affected by the catalyst support. With SBA-15 as the support, the selectivity of EHP can reach 90%. Moreover, Co/ZrO2 gave an extraordinarily high GVL productivity of 1.50 mol gmetal-1 h-1 and displayed excellent stability and reusability. Interestingly, coke has a positive effect on the enhancement of GVL yield. AL dimers and trimers were identified as the coke species in the hydrogenation of EL. As far as we know, this is the first work conducting the flexible transformation of EL on cobalt catalysts.
- Cen, Youliang,Zhu, Shanhui,Guo, Jing,Chai, Jiachun,Jiao, Weiyong,Wang, Jianguo,Fan, Weibin
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p. 9152 - 9160
(2018/03/21)
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- Synthesis of Ethyl-4-ethoxy Pentanoate by Reductive Etherification of Ethyl Levulinate in Ethanol on Pd/SiO2-C Catalysts
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The synthesis of biomass-derived ethers to be used as biofuels or biofuel additives has attracted much attention. Following the recently reported synthesis of etherified ester ethyl-4-ethoxy pentanoate (EEP) from γ-valerolactone (GVL) in ethanol catalyzed by H-beta zeolite, an alternative route to prepare EEP in high yield has been developed by reductive etherification of ethyl levulinate (EL) in ethanol at 140 °C under 0.5 MPa H2 with a silica-modified Pd/C catalyst. The ether production likely follows a tandem acetalization–hydrogenolysis process with ethyl-4,4-diethoxy pentanoate (EDEP) as the intermediate. The acetalization step can be favored by introducing acidic materials, such as SiO2–carbon or beta zeolite, as a cocatalyst. The combination of the Pd/SiO2-C and beta zeolite mixture leads to 100 % EL conversion and 93 % EEP selectivity under optimized reaction conditions. For the first time, the standard molar combustion enthalpy of as-prepared EEP is measured by using a static oxygen bomb, and the value of which is determined to be about ?5658 kJ mol?1, which is much larger than that of GVL (?2650 kJ mol?1).
- Cui, Qianqian,Long, Yinshuang,Wang, Yun,Wu, Haihong,Guan, Yejun,Wu, Peng
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p. 3796 - 3802
(2018/10/24)
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- “Inverse” Frustrated Lewis Pairs: An Inverse FLP Approach to the Catalytic Metal Free Hydrogenation of Ketones
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For the first time have boron-containing weak Lewis acids been demonstrated to be active components of Frustrated Lewis Pair (FLP) catalysts in the hydrogenation of ketones to alcohols. Combining the organosuperbase (pyrr)3P=NtBu with the Lewis acid 9-(4-CF3-C6H4)-BBN generated an “inverse” FLP catalyst capable of hydrogenating a range of aliphatic and aromatic ketones including N-, O- and S-functionalized substrates and bio-mass derived ethyl levulinate. Initial computational and experimental studies indicate the mechanism of catalytic hydrogenation with “inverse” FLPs to be different from conventional FLP catalysts that contain strong Lewis acids such as B(C6F5)3.
- Mummadi, Suresh,Brar, Amandeep,Wang, Guoqiang,Kenefake, Dustin,Diaz, Rony,Unruh, Daniel K.,Li, Shuhua,Krempner, Clemens
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supporting information
p. 16526 - 16531
(2018/10/20)
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- Enhancing the conversion of ethyl levulinate to γ-valerolactone over Ru/UiO-66 by introducing sulfonic groups into the framework
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The conversion of ethyl levulinate (EL) to γ-valerolactone (GVL) is an important reaction in biomass conversion. This process undergoes two consecutive reactions: hydrogenation and transesterification of the intermediate compound, i.e. ethyl 4-hydroxypentanoate, which are catalyzed by metal nanoparticles and acid sites, respectively. In this study, we explored the catalytic activity of Ru supported on metal organic frameworks aiming to develop efficient metal-acid bifunctional catalysts for this green process. UiO-66 and its analogues with various substituted groups (-SO3H, -NH2 and -NO2) were employed in this study. The Ru particle size, oxidation state and reducibility were characterized by TEM, H2-TPR, and XPS. The results suggest that the introduction of functional groups reduces the hydrogenation activity of pristine Ru/UiO-66 to various extents. Catalyst modified with -SO3H group shows much higher acidic catalytic performance while showing hydrogenation activity towards CO bonds, thus improving the overall transformation of EL to GVL due to the presence of strong Br?nsted acid sites.
- Yang, Jie,Huang, Wenjuan,Liu, Yongsheng,Zhou, Tao
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p. 16611 - 16618
(2018/05/23)
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- Synergetic Catalysis of Bimetallic CuCo Nanocomposites for Selective Hydrogenation of Bioderived Esters
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Bimetallic catalysts based on nonprecious transition metals have attracted increasing attention because of their unique synergistic effects in catalytic reactions, but the understanding of the nature of synergistic effects and their roles in a specific hydrogenation reaction remains lacking. Herein, a series of bimetallic CuxCoy/Al2O3 (x/y = 5:1, 2:1, 1:1, 1:2, 1:5) nanocomposite catalysts were fabricated via the successive calcination and reductive activation process of layered double hydroxide precursors. Their catalytic performance in the selective hydrogenation of bioderived ethyl levulinate to 1,4-pentanediol (1,4-PeD) depended sensitively on the chemical composition of bimetallic CuCo catalysts. The optimal bimetallic Cu2Co1/Al2O3 catalyst exhibited markedly improved catalytic activity and selectivity compared to monometallic Cu/Al2O3, as confirmed by its lower apparent activation energy barrier of 65.1 kJ mol-1 of the rate-determining step and its high selectivity of 93% to 1,4-PeD. Detailed characterization analyses and intrinsic catalytic studies revealed that the presence of CoOx species in the bimetallic CuxCoy/Al2O3 catalysts enhanced the metallic Cu dispersion and H2 activation ability. More importantly, the strong electronic interaction at the interface of Cu and adjacent CoOx species modified the chemical states of Cu species to create proper surface Cu0/Cu+ distributions and, particularly, provided synergic catalysis sites of Cu and electron-deficient CoOx species, which was primarily responsible for the excellent catalytic performance of bimetallic CuCo catalysts. The bimetallic CuCo catalysts exhibited good stability in both batch and fixed-bed continuous flow reactions. Furthermore, present CuCo nanocomposite catalyst could be applied to the highly selective hydrogenation of other carboxylic esters and lactones to synthesize valuable C4, C5, and C6 diols.
- Wu, Jun,Gao, Guang,Sun, Peng,Long, Xiangdong,Li, Fuwei
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p. 7890 - 7901
(2017/11/10)
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- Hydrogenation of γ-valerolactone in ethanol over Pd nanoparticles supported on sulfonic acid functionalized MIL-101
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A ligand-based solid solution approach is employed to incorporate sulphonic acid functional groups into the porous coordination polymer Cr-MIL-101. Loaded with Pd nanoparticles these Pd/MIL-101-SO3H materials act as bifunctional catalysts for the one-pot conversion of γ-valerolactone into ethyl valerate (up to 83% yield). The catalysts were extensively characterized before and after reaction. The influence of the sulfonic acid group density and the reaction conditions on the catalytic activity was systematically investigated and the reaction network for γ-valerolactone upgrading was discussed.
- Zhang, Damin,Ye, Feiyang,Guan, Yejun,Wang, Yimeng,Hensen, Emiel J. M.
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p. 39558 - 39564
(2014/12/09)
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- Enhanced hydrogenation of ethyl levulinate by Pd-AC doped with Nb 2O5
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Gamma-valerolactone (GVL), as sustainable feedstock for high-value chemicals and fuel, has been produced by hydrogenation of levulinic acid (LA) or ethyl levulinate (EL). In this work, Pd nanoparticles supported on Nb 2O5-doped activated carbon (AC) were prepared via wet incipient impregnation with PdCl2 followed by reduction with NaBH4. The dispersed niobia plays a bifunctional role in the catalytic process: stabilizing Pd nanoparticles and acting as an acidic co-catalyst. This synergistic effect between niobia and Pd leads to an unprecedented high activity of supported Pd catalysts in EL hydrogenation. The synergy is correlated with both the niobia loading and calcination temperature, with 10 wt% Nb2O5 calcined at 500 °C showing the best performance (EL conversion of 87% and GVL selectivity of 97%) under mild reaction conditions (100 °C and 0.5 MPa H2). This journal is the Partner Organisations 2014.
- Ye, Feiyang,Zhang, Damin,Xue, Teng,Wang, Yimeng,Guan, Yejun
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supporting information
p. 3951 - 3957
(2014/08/05)
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- New generation biofuels: γ-Valerolactone into valeric esters in one pot
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Ethyl valerate and pentyl valerate, suitable as a gasoline additive and diesel component respectively, can be obtained in a one pot one step reaction from γ-valerolactone, readily available from lignocellulosic biomass. The reaction takes place in ethanol under H2 through nucleophilic addition of the alcohol to the carboxylic group giving hydroxypentanoate, dehydration to pentenoate and hydrogenation to the saturated ester. The bifunctional catalyst used consists of a non noble metal, namely copper, supported on an amorphous weakly acidic material, therefore representing an interesting alternative to Pt-zeolite catalysts. Pentyl valerate can be obtained in one pot with conversions >90% and selectivity up to 83%.
- Chan-Thaw, Carine E.,Marelli, Marcello,Psaro, Rinaldo,Ravasio, Nicoletta,Zaccheria, Federica
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p. 1302 - 1306
(2013/03/29)
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- Enantioselective hydrogenation of levulinic acid esters in the presence of the RuII-BINAP-HCl catalytic system
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The rate of hydrogenation of γ-ketoesters MeCOCH2CH 2COOR (R = Et, Pri, But) in the presence of the chiral RuII-BINAP catalyst (BINAP is 2,2′- bis(diphenylphosphino)-1,1′-binaphthyl) greatly increases upon the addition of 5-10 equivalents of HCl with respect to ruthenium. In the hydrogenation of ethyl levulinate, the optically active γ-hydroxy ester initially formed would cyclize by ~95% to give γ-valerolactone with optical purity of 98-99% ee. When the Ru(COD)(MA)2-BINAP-HCl catalytic system is used (COD is 1,5-cyclooctadiene, MA is 2-methylallyl), complete conversion of the ketoester (R = Et) in EtOH is attained in 5 h at 60°C under an H2 pressure of 60-70 atm.
- Starodubtseva,Turova,Vinogradov,Gorshkova,Ferapontov
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p. 2374 - 2378
(2007/10/03)
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- Asymmetric Reduction of Functionalized Ketones with a Sodium Borohydride-(L)-Tartaric Acid System
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The sodium borohydride-(L)-tartaric acid system is effective for the asymmetric reduction of prochiral ketones if they are functionalized on the α- or β-carbon with a group that can chelate to the chirally modified borohydride.
- Yatagai, Masanobu,Ohnuki, Takashi
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p. 1826 - 1828
(2007/10/02)
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