Production of Alkyl Levulinates from Carbohydrate-Derived Chemical Intermediates Using Phosphotungstic Acid Supported on Humin-Derived Activated Carbon (PTA/HAC) as a Recyclable Heterogeneous Acid Catalyst

This work reports a straightforward and high-yielding synthesis of alkyl levulinates (ALs), class promising biofuel, renewable solvent, chemical feedstock origin. ALs were prepared by the acid-catalyzed esterification levulinic acid (LA) alcoholysis carbohydrate-derived platforms, such as furfuryl alcohol (FAL) α-angelica lactone (α-AGL). Phosphotungstic (PTA) was chosen solid catalyst for transformation, which heterogenized on humin-derived activated carbon (HAC) superior recyclability. Using HAC support expands scope valorizing humin, complex furanic resin produced inevitably side product (often considered waste) during hydrolysis/dehydration sugars polymeric carbohydrates. Under optimized conditions (150 °C, 7 h, 25 wt.% 20%PTA/HAC-600 catalyst), ethyl levulinate (EL) obtained in an 85% isolated yield starting from FAL. general synthetic protocol, EL 88% 84% yields LA α-AGL, respectively. The successfully recovered reaction mixture recycled five cycles. A marginal loss observed consecutive catalytic cycles due to partial leaching PTA support.