Catalytic Upgrading of 5‐Hydroxymethylfurfural to Drop‐in Biofuels by Solid Base and Bifunctional Metal–Acid Catalysts

Abstract

Design and synthesis of effective heterogeneous catalysts for the conversion of biomass intermediates into long chain hydrocarbon precursors and their subsequent deoxygenation to hydrocarbons is a viable strategy for upgrading lignocellulose into distillate range drop-in biofuels. Herein, we report a two-step process for upgrading 5-hydroxymethylfurfural (HMF) to C9 and C11 fuels with high yield and selectivity. The first step involves aldol condensation of HMF and acetone with a water tolerant solid base catalyst, zirconium carbonate (Zr(CO3 )x ), which gave 92 % C9 -aldol product with high selectivity at nearly 100 % HMF conversion. The as-synthesised Zr(CO3 )x was analysed by several analytical methods for elucidating its structural properties. Recyclability studies of Zr(CO3 )x revealed a negligible loss of its activity after five consecutive cycles over 120 h of operation. Isolated aldol product from the first step was hydrodeoxygenated with a bifunctional Pd/Zeolite-β catalyst in ethanol, which showed quantitative conversion of the aldol product to n-nonane and 1-ethoxynonane with 40 and 56 % selectivity, respectively. 1-Ethoxynonane, a low oxygenate diesel range fuel, which we report for the first time in this paper, is believed to form through etherification of the hydroxymethyl group of the aldol product with ethanol followed by opening of the furan ring and hydrodeoxygenation of the ether intermediate.

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.…”

“…S1 †). The molecular structures of these intermediates were determined by 13 C NMR measurement, which conrmed the synthesis of the desired products by aldol condensation without any impurities (Fig. S2-S4 and S6(a) †).…”

“…For monitoring the saturation of C]C and C]O bonds by hydrogenation in the solid intermediates, the sole Pd/C catalyst was used at relatively low temperatures according to the hydrodeoxygenation process. The structures of these hydrogenation intermediates were identied using 13 C NMR analysis (Bruker BioSpin GmbH)…”

“…The condensations of FF and CH, HMF and CP and HMF and CH were carried out by the procedure mentioned above, and the solid intermediates were labeled as FF-CH-FF, HMF-CP-HMF and HMF-CH-HMF, respectively. The structures of the aldol condensation intermediates were identied using 13 C NMR analysis (Bruker BioSpin GmbH) …”

Efficient utilization of potash alum as a green catalyst for production of furfural, 5-hydroxymethylfurfural and levulinic acid from mono-sugars

“…Moreover, HMF itself is a promising platform chemical employed to produce an array of chemicals and fuel such as gasoline, diesel, polymers, solvents 15 and other value added productss. 16,17 Similarly, LA is one of the top ten biomassderived platform chemicals that can be used to produce alternative of petroleum-derived chemicals and transportation fuels. [18][19][20] In addition to HMF, LA, and furfural (FL) which are produced from cellulosic and hemi cellulosic component of the lignocellulosic biomass, have sought attention as a major precursor for the production of biofuel.…”