Support Screening Studies on the Hydrogenation of Levulinic Acid to γ-Valerolactone in Water Using Ru Catalysts

Abstract

γ-Valerolactone (GVL) has been identified as a sustainable platform chemical for the production of carbon-based chemicals. Here we report a screening study on the hydrogenation of levulinic acid (LA) to GVL in water using a wide range of ruthenium supported catalysts in a batch set-up (1 wt. % Ru, 90 • C, 45 bar of H 2 , 2 wt. % catalyst on LA). Eight monometallic catalysts were tested on carbon based(C, carbon nanotubes (CNT)) and inorganic supports (Al 2 O 3 , SiO 2 , TiO 2 , ZrO 2 , Nb 2 O 5 and Beta-12.5). The best result was found for Ru/Beta-12.5 with almost quantitative LA conversion (94%) and 66% of GVL yield after 2 h reaction. The remaining product was 4-hydroxypentanoic acid (4-HPA). Catalytic activity for a bimetallic RuPd/TiO 2 catalyst was by far lower than for the monometallic Ru catalyst (9% conversion after 2 h). The effects of relevant catalyst properties (average Ru nanoparticle size, Brunauer-Emmett-Teller (BET) surface area, micropore area and total acidity) on catalyst activity were assessed.

New Frontiers in the Catalytic Synthesis of Levulinic Acid: From Sugars to Raw and Waste Biomass as Starting Feedstock

“…Among the target products, levulinic acid (LA) is the main compound of biomass hydrolysis, which has been classified by the United States Department of Energy as one of the top-12 promising building blocks [7]. LA represents a valuable intermediate for the synthesis of several chemicals for application in fuel additives, fragrances, solvents, pharmaceuticals, and plasticizers [8][9][10][11][12][13]. LA, also known as 3-acetylpropionic acid, 4-oxovaleric acid, or 4-oxopentanoic acid, is a very interesting platform chemical, because of its versatile chemistry, including one carbonyl, one carboxyl and α-H in its inner structure, looking like a short chain and non-volatile fatty acid.…”

Selective Levulinic Acid Hydrogenation in the Presence of Hybrid Dendrimer‐Based Catalysts. Part I: Monometallic

“…The most characteristic literature data on levulinic acid hydrogenation are presented in Table S1 in the Supporting Information. As a rule, hydrogenation of levulinic acid in the presence of heterogeneous Ru catalysts was conducted at 130–200 °C (more rarely at 50–90 °C) and 15–50 bar of hydrogen, using activated carbon, silica, alumina, or titania as carriers and water,, 1,4‐dioxane, and alcohols as solvents . Herein, turnover frequencies (TOFs) reached values mostly of 100–1000 h −1 (Table S1).…”

Hydrogenation of levulinic acid to γ-valerolactone over anatase-supported Ru catalysts: Effect of catalyst synthesis protocols on activity

“…The support choice was fixed to reduce the complexity of possible variations during the catalyst synthesis procedure. In addition, we have recently shown good catalytic results for Ru on anatase TiO 2 [30]. Perusal of the literature on Ru/TiO 2 catalyzed LA hydrogenation ( Table 1) finally shows that catalyst performance not only depends on support choice and catalyst synthesis parameters, but that a strong dependence on the choice of solvent can also be expected.…”

“…Recently, some of us reported on a catalyst screening study for LA hydrogenation in water (90°C, 45 bar H 2 ) using a wide range of supported Ru-catalysts (1 wt.% Ru on C, CNT, Al 2 O 3 , TiO 2 , ZrO 2 , Nb 2 O 5 and HBeta-12.5) and again found that TiO 2 (anatase form, A100) performed better than for Ru/ZrO 2 in this solvent [30]. The results listed above thus show the potential of TiO 2 as support for this reaction and an overview of titania-supported Ru catalysts for LA hydrogenation is given in Table 1.…”

“…Besides variations in support phase composition, many different synthetic procedures for titania-supported Ru catalyst preparation have been reported varying in the choice of, e.g., metal precursor, impregnation method and activation procedure (Table 1), which all may affect catalyst performance. Wet impregnation is most commonly used method for the synthesis of these Ru/TiO 2 catalysts [19,20,25,29], using Ru precursors such as RuCl 3 , Ru(NO)(NO 3 ) 3 , Ru(acac) 3 , Ru (NH 3 ) 6 Cl 3 or Ru 3 (CO) 12 [19,20,25,[29][30][31][32][33][34][35]. Limited information is available on the effects of these synthesis parameters on LA hydrogenation activity for Ru/TiO 2 catalysts.…”