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Vanillin production from chemical oxidation of Pinus spp . Kraft lignin is investigated. At a temperature of 130 °C, an oxygen partial pressure of 3 bar, a total pressure of 9 bar, and a lignin concentration of 60 g/L in an alkaline medium of 2 N NaOH, a maximum vanillin yield of 10% is obtained. On the basis of experimental results in a batch reactor operated under various conditions of temperature, oxygen partial pressure, total pressure, initial lignin concentration and pH, a kinetic model is proposed to simulate vanillin production from oxidation of Kraft lignin. The reaction rate of vanillin production is, for pH > 11.5, r C = k NC O 2 1.75 L − k CI O 2 C and, for pH < 11.5, r C = k NC O 2 1.75 L − Af (pH)C 2 . An attempt to predict pH variation during the reaction is also made. The overall flowsheet of the process is briefly addressed, and the recovery of vanillin by adsorption is discussed.
Fargues et al. (1996) studied this question.