Environmentally Friendly Synthesis of γ-Valerolactone by Direct Catalytic Conversion of Renewable Sources

Abstract

Gamma-valerolactone is a valuable chemical that can be obtained by catalytic methods from nonedible vegetable biomass. However, the demand is felt for more environmentally friendly and cost-effective production processes. The topic is reviewed in this paper from the perspective of catalyst design. Focus is on those systems enabling one-pot reaction sequences in the liquid phase at low energy expenses and combining metal and acid sites, spanning from homogeneous to heterogeneous catalysts. A final section is dedicated to continuous flow applications. The 230 references cover the most significant achievements published in the literature from January 2011 to July 2014 and highlight critical issues and future trends.

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

“…Standard reaction conditions were selected based our previous results [19,38,39], and are given in Table 2. The lower reaction temperature selected for the reaction in water (90°C) compared to dioxane (150°C) reflects the surprisingly high activity of Ru-based hydrogenation catalysts under aqueous conditions, for which the underlying reasons have been recently discussed [15,17,19,38,41,42]. The hydrogen pressure was set at 45 bar for all experiments.…”

“…Recently, Liguori and Barbaro [17] published a comprehensive review on the direct catalytic conversion of renewable sources to GVL with an emphasis on the heterogeneous catalysts that have been used for this reaction. Noble metal-based catalysts are most commonly and successfully employed, with Ru-based ones in particular showing high activity and selectivity to GVL [14,[18][19][20][21].…”

Hydrogenation of Levulinic Acid over Nickel Catalysts Supported on Aluminum Oxide to Prepare γ-Valerolactone

“…The first step in producing GVL is hydrogenation of LA to form an intermediate, followed by an intramolecular cyclization reaction. At present, high temperatures, organic solvents, additives, complex separation procedures, and managing relatively high hydrogen pressures are often required for efficiently producing GVL, which together entail substantial energy inputs and the generation of large amounts of waste [11]. Many noble metal catalysts, such as Ru, Ir, Rh, and Pt, have been investigated for the hydrogenation of LA [12][13][14][15][16][17][18].…”

Acid–Base Bifunctional Hf Nanohybrids Enable High Selectivity in the Catalytic Conversion of Ethyl Levulinate to γ-Valerolactone

“…In addition, it can be employed for producing biofuels and fuel additives (e.g., 2-methyltetrahydrofuran) [7], and as a key intermediate in the synthesis of fine chemicals (e.g., pentenoic acid and α-methylene-γ-valerolactone (MeGVL)), as shown in Scheme 1 [8,9]. Typically, GVL can be prepared from lignocellulose via sequential catalytic pathways involving various reactions such as hydrolysis, isomerization, dehydration, etherification, esterification, hydrogenation, and lactonization [10][11][12][13][14][15][16].…”