In Situ Generated Catalyst System to Convert Biomass‐Derived Levulinic Acid to γ‐Valerolactone

Abstract

This is the first report of HCl/ZrO(OH)2 catalysts prepared in situ by the autonomous decomposition of ZrOCl2⋅8 H2O in levulinic acid (LA)/2‐butanol solution, which catalyzed the esterification of LA in tandem with hydrocyclization to γ‐valerolactone (GVL) by Meerwein–Ponndorf–Verley (MPV) reduction without the use of external H2. A maximum GVL yield of 92.4 % from neat LA and a GVL formation rate of 1092.2 μmol g−1 min−1 were achieved in 2‐butanol at 240 °C in 2 h. The in situ generated ZrO(OH)2 was characterized comprehensively and its unexpected catalytic efficiency was attributed mainly to its extremely high surface area. A crude LA stream from the acid hydrolysis of cellulose was extracted into 2‐butanol and subjected to this catalyst system to give a GVL yield of 82.0 % even in the presence of humins.

Recyclable Earth‐Abundant Metal Nanoparticle Catalysts for Selective Transfer Hydrogenation of Levulinic Acid to Produce γ‐Valerolactone

“…Other supported NP catalysts employed for the hydrogenation of LA to GVL include Au NPs supported on acid‐tolerant ZrO 2 ,, Ru NPs supported on TiO 2 , Cu supported on ZrO 2 , and Ni promoted Cu‐SiO 2 nanocomposite catalysts . In situ generated HCl/ZrO(OH) 2 catalyst system was also investigated in the hydrogenation of LA to GVL . Recently, the TiO 2 supported Pt catalyst with the acid activated bentonite as the co‐catalyst was used in the second‐step GVL production from sugarcane bagasse .…”

Recent advances in the production of γ‐valerolactone from biomass‐derived feedstocks via heterogeneous catalytic transfer hydrogenation

“…The application of in situ generated transition metal hydroxides/HCl for conversion of LA to GVL using 2‐butanol as hydrogen donor has also been reported . Various precursor salts including chloride salts of Ba, Mg, Cu, Mn, Cr, Al, Sn and Zr as well as zirconium nitrate and zirconium sulfate were tested and the best catalytic performance was observed from ZrOCl 2 .8H 2 O with 99.9% LA conversion and 85% GVL yield after 1 h reaction at 240 °C using a 5 wt% LA in 2‐butanol solution and 5 mol% salt precursor relative to LA.…”

Switching Selectivity in the Hydrogen Transfer Reduction of Furfural

“…Recently, the catalytic transfer hydrogenation (CTH) of levulinic acid for the synthesis of gammavalerolactone (GVL) by Meerwein–Ponndorf–Verley (MPV) reduction using cheap metal oxides or hydroxides (especially Zr‐based materials) has received increasing attention . The same strategy was used for the production of 2,5‐bishydroxymethyl furan from 5‐hydroxymethyl furfural …”