Integration of Heterogeneous Acid and Base Catalysis for Clean Synthesis of Jet‐Fuel Precursor from Carbohydrates

Abstract

AbstractC12 branched alkane fuel precursor was produced from carbohydrates using an efficient integrated solid acid and base catalysis approach involving: i) isomerisation‐dehydration of carbohydrates to 5‐(hydroxymethyl)furfural (HMF) over solid acid catalyst having both Lewis and Brónsted sites) in a biphasic MIBK (methylisobutylketone): water + DMSO solvent system and ii) Claisen‐Schmidt condensation of crude HMF with MIBK over solid base catalyst. Initially, high yield of jet fuel precursor, (E)‐1‐(5‐(hydroxymethyl)furan‐2‐yl)‐5‐methylhex‐1‐en‐3‐one from pure HMF and MIBK was achieved over basic CaMgAl(231) catalyst. The glucose dehydration to HMF was optimized in biphasic MIBK: H2O‐NaCl: DMSO (8:1.5:0.5; v/v/v) system, with complete glucose conversion and 42% HMF yield over Zr‐Mont possessing both Lewis and Brønsted acid sites. In an integrated dehydration + Claisen‐Schmidt condensation sequence, Zr‐Mont catalyst was filtered off and the crude HMF with MIBK underwent Claisen‐Schmidt condensation over CaMgAl(231) catalyst. The overall 32% yield of Claisen‐Schmidt condensation product was achieved from glucose. MIBK acting also as a product extractant, could be recovered upto 80%.