Highly Selective Hydrogenation of Levulinic Acid to γ-Valerolactone Over Ru/ZrO2 Catalysts

Abstract

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.Graphical Abstract Pre-treatment changes the performance for ruthenium nanoparticles on zirconia supports, giving TONs over 3500 in the hydrogenation of levulinic acid to γ-valerolactone with over 99% yield. Electronic supplementary materialThe online version of this article

Solar Light Induced Photon-Assisted Synthesis of TiO2 Supported Highly Dispersed Ru Nanoparticle Catalysts

“…In addition, an interplane distance of 2.1 Å corresponding to the (101) atomic planes of metallic Ru was measured on TEM images [29]. The mean Ru nanoparticle size derived from TEM images being of 0.6 nm, the Ru nanoparticles that were supported on TiO 2 could be considered in a first approximation as being composed in average of only about 3–4 atomic layers.…”

Recent Advances in Ruthenium-Catalyzed Hydrogenation Reactions of Renewable Biomass-Derived Levulinic Acid in Aqueous Media

“…Gao et al (2018) disclosed results on the stability of 2.5 wt.% Ru/ZrO 2 catalysts applied in the transfer hydrogenation reaction of LA to GVL with a mixture of formic acid/formate at 150 • C in aqueous media, and found that the incorporation of 0.1 wt.% SiO 2 to the support enormously stabilized the system and the catalyst Ru/ZrO 2 -SiO 2 retained its activity after recycling in three consecutive runs, whereas the activity of Ru/ZrO 2 catalyst significantly decreased after recycling already in the first consecutive run. The catalytic properties of four different Ru/ZrO 2 systems have been evaluated in the hydrogenation of LA to GVL in aqueous media; catalytic activity is strongly influenced by the pre-treatment method and the most active catalyst was obtained after impregnation of RuCl 3 •3H 2 O on pre-calcined zirconia support, followed by reduction with dihydrogen to give ruthenium metal particles of a size between 3.0 and 4.0 nm with an uniform dispersion (Filiz et al, 2017). Using this Ru/ZrO 2 catalyst in the aqueous phase hydrogenation of LA at 170 • C under 27 bar of H 2 within 7 h at a molar ratio of LA/Ru = 2100, the catalytic activity obtained was 297 TOFs per hour with a conversion of LA of 99.0 mol% and a selectivity toward GVL of 99.9 mol% ( Table 1).…”

Electron-Rich Ruthenium on Nitrogen-Doped Carbons Promoting Levulinic Acid Hydrogenation to γ-Valerolactone: Effect of Metal–Support Interaction

“…Ru nanoparticles (NPs) have been considered a benchmark catalyst for LA hydrogenation with its excellent activity and selectivity among the noble metal catalysts, such as Pt, Au, Rh, Ru, and Ir. − Alloying with another metal to form bimetallic NPs (RuSn, RuRe, RuNi, and RuPd) benefits the stability. ,− In addition, the catalytic performance can be tuned by using the support of different metal oxides such as TiO 2 , Nb 2 O 5 , ZrO 2 , Al 2 O 3 , SiO 2 , MgO, and other oxide hybrids resulting from the synergic effect between Ru NPs and oxide supports. ,− Metallic Ru 0 was conventionally considered the active species for LA hydrogenation . However, the inevitable coexistence of RuO 2 , RuO 3 , and RuO x H y with Ru 0 on the surface makes the identification of the electronic state of Ru 0 more complicated. , Scrutiny of the published work, even for metallic Ru 0 , shows that several inconsistent binding energies have been presented.…”