Catalytic conversion of whey permeate into 5-hydroxymethylfurfural: Optimization and kinetic modeling approach

Abstract

This work presents an efficient catalytic system for the valorization of whey permeate into 5-hydroxymethylfurfural (HMF). Lactose was studied as the model carbohydrate. The side products formed during the reaction were levulinic acid (LA), formic acid (FA), and humins. It was found that 0.25 mol/L of acetic acid and 0.21 mol/L of AlCl3·6H2O showed a synergistic effect on the HMF yield in γ-valerolactone and water as the binary solvent system. Three independent reaction parameters (reaction temperature, time, and AlCl3·6H2O concentration) were investigated to understand their effects on the formation of HMF, LA, and FA. The maximum HMF yield (59 mol%) for lactose was obtained at the optimum conditions (135 °C, 100 min, and 0.21 mol/L AlCl3·6H2O). The developed catalytic system was applied on different concentrations of whey permeates namely, whey permeate, ultrafiltered whey permeate, combined reverse osmosis-nanofiltered whey permeate after 30% evaporation, and whey permeate powder. Amongst all, the application of the developed catalytic system on whey permeate powder showed promising results, where 74 mol% HMF yield was obtained in a shorter reaction time (40 min) than lactose. The kinetic study demonstrated all the possible reaction pathways occurring during HMF formation for lactose and whey permeate powder. Key findingThe reaction kinetics for whey permeate powder discloses various possible reaction pathways for lactose to HMF conversion.