Renewable Energy, Vol.167, 282-293, 2021
Acetalization of 5-hydroxymethyl furfural into biofuel additive cyclic acetal using protic ionic liquid catalyst- A thermodynamic and kinetic analysis
This work investigates the thermodynamics and kinetics of the synthesis of 5-HMF-cyclic acetal, a fuel additive, from 5-HMF and 1,3-propanediol using lab synthesized, environmentally benign Bronsted acidic ionic liquid (IL) catalyst. Firstly, a thermodynamic study of the acetalization of 5-HMF with different mono and polyalcohols was carried out to evaluate the thermodynamic properties of critical temperature (T-c), critical volume (V-c), critical pressure (P-c), Gibbs free energy of formation (Delta G(f)(0)), enthalpy of formation (Delta H-f(0)), and heat capacity (C-p) using group contribution methods. Then, kinetics of 5-HMF acetalization with 1,3-propanediol was investigated in a batch autoclave using Bronsted acidic IL catalyst and effect of reaction parameters temperature, molar ratio of reactants and time were investigated on the conversion of 5-HMF into 5-HMF-cyclic acetal product and optimized for high 5-HMF conversion and cyclic acetal yield. A first-order pseudo-homogeneous kinetic model with a squared regression coefficient R-2 > 0.99 fitted well with experimental data. The activation energy of the acetalization reaction is estimated to be 83 kJ/mol for the 1st order kinetics. Based on the catalyst activity, a plausible reaction mechanism was proposed for the acetalization reaction of 5-HMF and 1,3-propanediol. Finally, this manuscript reports an efficient method for the production of fuel-additive compound and valuable information for predicting the thermodynamic properties for the pure organic components. (c) 2020 Elsevier Ltd. All rights reserved.