Efficient catalytic hydrogenation of alkyl levulinates to γ-valerolactone (original) (raw)
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ACS Sustainable Chemistry & Engineering, 2016
Solvent-free conversion of bio-derived levulinic acid (LA) to γ-valerolactone (GVL) has been achieved by new pyrazolylphosphite and pyrazolylphosphinite ruthenium(II) complexes as catalyst precursors, using both formic acid and molecular hydrogen as hydrogen sources. The reactions were very efficient at moderate temperatures of 100 to 120 °C. With a catalyst loading of 0.1%, 100% LA conversion (with hydrogen gas) was achieved with 100% GVL selectivity at 110 °C and 15 bar. The catalyst was recyclable up to three times without significant loss of activity and selectivity. The catalyst precursors are found to be more efficient when the hydrogen source was molecular hydrogen as compared to formic acid. NMR studies of reactions involving formic acid as a hydrogen source indicate that the initial step in the reaction involves the decomposition of formic acid to CO 2 and H 2 .
Hydrogenation of levulinic acid to γ-valerolactone over copper catalysts supported on γ-Al2O3
Catalysis Today, 2015
Highlights Catalyst preparation protocols strongly affect catalyst performance of Ru on titania (anatase) for the catalytic hydrogenation of levulinic acid to valerolactone Best results regarding activity were obtained when using a RuNO(NO3)3 precursor (when considering TOF) without an intermediate calcination step and 10% hydrogen in the reduction gas. The information can be used to prepare optimum Ru based catalysts for the catalytic hydrogenation of levulinic acid 2 Abstract γ-Valerolactone (GVL) is a value-added renewable chemical with great potential and can be obtained from biomass by the hydrogenation of levulinic acid (LA) using metal-based catalysts, such as Ru/TiO2. We here report an in depth study of the effect of catalyst synthesis parameters on the performance of Ru/TiO2 (anatase), varying the nature of the Ruprecursor and the conditions of the calcination and/or reduction step. Catalyst performance was evaluated under batch conditions at a hydrogen pressure of 45 bar and using either water (90 °C) or dioxane (150 °C) as solvent. The experiments showed that catalyst activity depends greatly on the Ru precursor used (RuCl3, RuNO(NO3)3, Ru(NH3)6Cl3). Best results when considering the turnover frequencies (TOF) of the catalysts were obtained using the RuNO(NO3)3 precursor, whereas RuCl3 performed better when considering the initial rate based on Ru intake. An intermediate calcination step and the use of a hydrogen-rich sweep gas during the final reduction step were shown to have a negative impact on catalyst activity. Characterization of the fresh catalysts by BET and TEM provided valuable insight in the relation between the catalyst structure and its activity.
Highly Selective Hydrogenation of Levulinic Acid to γ-Valerolactone Over Ru/ZrO2 Catalysts
Catalysis Letters, 2017
We studied the catalytic hydrogenation of levulinic acid over zirconia supported ruthenium catalysts. Four different Ru/ZrO 2 catalysts were prepared by different pre-treatments and using different zirconium supports (ZrO x (OH) 4−2x and ZrO 2). Although the final compositions of the catalysts are the same, the pre-treatments strongly affect catalytic activity. Remarkably, one of the catalysts gave >99% yield of γ-valerolactone under mild conditions. This catalyst was also robust, and could be recycled at least four times without any loss in activity or selectivity. The activity is attributed to the presence of small ruthenium particles together with acidic sites on the catalyst.
Towards Production of γ-valerolactone via Hydrogenation of Aqueous Levulinic Acid
International Journal of Chemical Reactor Engineering, 2015
Synthesis of GVL (γ-valerolactone) via hydrogenation of aqueous LA (levulinic acid) with H2 over heterogeneous catalyst (Ru/C) was investigated. In the first part, a study of the influence of various operating conditions was conducted including that of temperature (90–180°C), stirring rate (500–1200 rpm), catalyst loading (0.1–2.0 g), hydrogen pressure (0.4–2.8 MPa) and initial LA concentration (0.5–2 M). In the second part, influence of supercritical CO2 (scCO2) on hydrogenation rate and GVL yield were investigated. Hydrogenation of aqueous LA under scCO2 and under N2 atmosphere was carried out in batch reactor at 150°C and was compared with the case when no additional gases were present. The result indicated that the use of scCO2 had no beneficial effect neither in terms of LA conversion nor hydrogenation rate when the amount of hydrogen was relatively low compared to the stoichiometry. This effect was mitigated when more hydrogen was present.
Catalysts
γ-valerolactone (GVL) is an important value-added chemical with potential applications as a fuel additive, a precursor for valuable chemicals, and polymer synthesis. Herein, different monometallic and bimetallic catalysts supported on γ-Al2O3 nanofibers (Ni, Cu, Co, Ni-Cu, Ni-Co, Cu-Co) were prepared by the incipient wetness impregnation method and employed in the solvent-free hydrogenation of levulinic acid (LA) to GVL. The influence of metal loading, metal combination, and ratio on the activity and selectivity of the catalysts was investigated. XRD, SEM-EDS, TEM, H2-TPR, XPS, NH3-TPD, and N2 adsorption were used to examine the structure and properties of the catalysts. In this study, GVL synthesis involves the single-step dehydration of LA to an intermediate, followed by hydrogenation of the intermediate to GVL. Ni-based catalysts were found to be highly active for the reaction. [2:1] Ni-Cu/Al2O3 catalyst showed 100.0% conversion of LA with >99.0% selectivity to GVL, whereas [2...
DOAJ (DOAJ: Directory of Open Access Journals), 2016
This work is devoted to the investigation of the possibility of use of ruthenium-containing catalysts on the basis of polymeric matrix of hypercrosslinked polystyrene (HPS) in hydrogenation of levulinic acid to gammavalerolactone, which is a semi-product for obtaining of liquid fuel components. Catalyst 5 %-Ru/MN100 was shown to allow carrying out the hydrogenation of levulinic acid in aqueous medium with high yields of gammavalerolactone (higher than 99 %) and it can compete with traditional catalyst 5 %-Ru/C. It is noteworthy that synthesized HPS-based catalyst has high activity, and thus the necessity of addition in reaction mixture of acidic co-catalysts is absent.