Conversion of raw lignocellulosic biomass into branched long‐chain alkanes through three tandem steps

Abstract

Synthesis of branched long-chain alkanes from renewable biomass has attracted intensive interest in recent years, but the feedstock for this synthesis is restricted to platform chemicals. Here, we develop an effective and energy-efficient process to convert raw lignocellulosic biomass (e.g., corncob) into branched diesel-range alkanes through three tandem steps for the first time. Furfural and isopropyl levulinate (LA ester) were prepared from hemicellulose and cellulose fractions of corncob in toluene/water biphasic system with added isopropanol, which was followed by double aldol condensation of furfural with LA ester into C15 oxygenates and the final hydrodeoxygenation of C15 oxygenates into branched long-chain alkanes. The core point of this tandem process is the addition of isopropanol in the first step, which enables the spontaneous transfer of levulinic acid (LA) into the toluene phase in the form of LA ester through esterification, resulting in LA ester co-existing with furfural in the same phase, which is the basis for double aldol condensation in the toluene phase. Moreover, the acidic aqueous phase and toluene can be reused and the residues, including lignin and humins in aqueous phase, can be separated and carbonized to porous carbon materials.

Synthesis of Diesel and Jet Fuel Range Cycloalkanes with Cyclopentanone and Furfural

“…Furfural is a bulk chemical which has been obtained on a commercial scale by the hydrolysis and dehydration of hemicellulose [27]. In recent years, series of diesel and jet fuel range chain alkanes were produced by the aldol condensation of furfural and acetone [15,19], methyl isobutyl ketone [28], pentanone [29,30], heptanone [31], levulinic acid [32], and angelica lactone [33], followed by hydrogenation/hydrodeoxygenation or hydrodeoxygenation (HDO). Cyclopentanone can be obtained (at high carbon yields of 62-95.8%) through the aqueous phase selectively hydrogenation and rearrangement of furfural [34][35][36][37][38].…”

Synthesis and Characterization of Furans and Levulinates Polymers: Derived from Cellulosic Carbohydrates via Aldol Condensation

“…As an important kind of platform chemicals derived from biomass, furans and levulinates have extensive advantages in synthesis of biofuels with different carbon chains or conversion to blending component in biodiesel [2]. C-C coupling reaction between furans and levulinates is an effective method in the synthesis of long-chained biofuels via aldol condensation [3][4][5].…”

Production of renewable long-chained cycloalkanes from biomass-derived furfurals and cyclic ketones

“…11 Aldol condensations of FF/HMF and/or their derivatives with carbonyl groups like acetone, [12][13][14][15][16] hydroxyacetone, 17 butaldehyde, 18 2-butanone, 19 methyl isobutyl ketone, 20 levulinic acid 11,21,22 and angelica lactone 23 have commonly been conducted to obtain the C 9 -C 16 fuel precursors, but these carbonyl compounds originate from fossil resources or are produced from biomass by multi-step reactions, leading to low efficiency and high cost for the entire synthesis. As an alternative, hydroxyalkylation-alkylation of FF and 2-methylfuran obtained by hydrodeoxygenation of FF was reported to produce C 15 fuel precursors with a branched carbon framework.…”