Practical high-yield production of vanillins from kraft or soda lignin using highly alkaline hydrogen peroxide treatment

This study was aimed to efficiently produce vanillin and its analogues (vanillins) from kraft or soda lignin in a system that is ready for practical installation owing to its possible operation in already-established mill equipment. This readiness is absent from most previous studies on the same topic. The knowledge accumulated in previous studies by the authors' group on lignin oxidation resulted in a conclusion that the highly alkaline hydrogen peroxide treatment (HA-H2O2-Tr) can be the best method. Another authors' recent study showed the efficient production of vanillins in HA-H2O2-Tr of a lignin model compound. In this study, kraft or soda lignin was treated in HA-H2O2-Tr to examine optimal conditions for the efficient production of vanillins. The highest yields of vanillins, 7.5 and 8.5 %, were obtained using HA-H2O2-Tr of kraft and soda lignin, respectively, under the following conditions: NaOH, FeCl3, and d-mannitol concentrations of 3.0 mol/L, 1.08 mmol/L, and 3.92 mmol/L, respectively; H2O2 solution (0.245 mol/L) addition rate and period of 80 mu L/min and 100 min, respectively; temperature of 90 degrees C. The highest yields were no lower than those in previous studies on the production of vanillins from kraft or soda lignin.