Levulinic Acid Esterification with n-Butanol over a Preyssler Catalyst in a Microwave-Assisted Batch Reactor: A Kinetic Study

Abstract

A Preyssler-type heteropolyacid supported on silica, synthesized and characterized by FTIR, was tested for levulinic acid (LA) esterification with n-butanol under microwave-assisted batch reaction conditions. The optimal conditions were found to be 40 mg of catalyst, a 5:1 n-butanol/LA molar ratio at 160 °C and 3 h, resulting in 77% conversion with 100% selectivity. The catalytic effect was observed at low temperatures (100 °C), and the microwave effect was observed at high temperatures (160 °C). Yield to levulinate was improved (82%) with CuSO 4 as a dehydrating agent. A kinetic study using a pseudohomogeneous reversible model (PH, E Forward = 31.60 kJ mol −1 and E Reverse = 11.53 kJ mol −1 ) and a Eley−Rideal model (ER, E = 31.06 kJ mol −1 ) provided the best fitting to the experimental data. The Preyssler-based catalyst has potential for sustainable synthesis of n-butyl levulinate, a promising fuel additive and can be used at least five times without a loss of activity.

Trifloaluminate Ionic Liquids Supported UIO‐67 as Lewis Acidic Catalyst for Excellent Synthesis of Alkyl Levulinates

“…Butyl levulinate, 1 H NMR (600 MHz, CDCl 3 , TMS): δ = 0.94 (t, J = 7.40 Hz, 3H),1.39-1.62(m,2H),2.2(s,3H) 2,58 (t, J = 6.5 Hz, 2H), 2.75 (t, J = 6.6 Hz, 2H), 4.08 (t, J = 6.7 Hz,2H) 13 C NMR (151 MHz, CDCl 3 ): δ 13.56, 18.97, 27.88, 29.75,30.49, 37.85, 64.43, 172.72, 206.51 GCMS: (EI) m/z (%) 172 (3, M + * ), 157 (8), 143 (3), 130 (6), 117 (15), 99 (90), 81 (5), 74 (28),71 (12), 57 (18), 43 (100).…”

“…[3][4][5][6] The recent literature has proposed several synthetic routes for LAEs. [4][5][6][7][8][9][10][11][12][13] For example, LAEs can be produced directly from the catalytic transformation of carbohydrates or raw biomass but with low efficiency and harsh conditions. [7] The direct esterification of levulinic acid with alcohol remains the most investigated strategy to synthesize LAEs over acid catalysts.…”

“…[7] The direct esterification of levulinic acid with alcohol remains the most investigated strategy to synthesize LAEs over acid catalysts. [6][7][8][9][10] However, the esterification reaction is governed by the thermodynamic equilibrium law. Water removal and a great excess of alcohol are often required to improve the productivity, and therefore, the subsequent energy-intensive product separation.…”

“…LAEs can be industrially used as polymer plasticizers, fragrances, and green solvents [3–6] . The recent literature has proposed several synthetic routes for LAEs [4–13] . For example, LAEs can be produced directly from the catalytic transformation of carbohydrates or raw biomass but with low efficiency and harsh conditions [7] .…”

“…For example, LAEs can be produced directly from the catalytic transformation of carbohydrates or raw biomass but with low efficiency and harsh conditions [7] . The direct esterification of levulinic acid with alcohol remains the most investigated strategy to synthesize LAEs over acid catalysts [6–10] . However, the esterification reaction is governed by the thermodynamic equilibrium law.…”