Process simulation of Kraft lignin oxidation for vanillin production

Abstract

Kraft lignin waste generated from Kraft pulping process can be potentially converted to a high value product such as vanillin. This work focused on feasibility study of vanillin production from Kraft lignin by oxidation reaction. A reaction model of Kraft lignin oxidation used in this work was selected from literature. The model was simulated by using MATLAB® software and many operating parameters such as feed concentration of Kraft lignin, reaction temperature, and oxygen partial pressure were optimized to obtain the highest yield of vanillin product. Then, three different separation methods i.e. vacuum distillation, solvent extraction, and solvent extraction followed by distillation were developed and compared in order to find the most suitable separation process for vanillin production. The simulation and comparison of different separation methods were done by using Aspen Plus® software. The result showed that the highest yield of vanillin at 9.25% could be obtained by using feed concentration of Kraft lignin at 30 grams/liter, temperature of 110 ⁰C, and oxygen partial pressure of 5 bars. The solvent extraction followed by distillation was found to be the most suitable separation method as it required low energy consumption and offered the lowest production cost. The economic analysis showed that in the best case, payback period and IRR of the vanillin production from Kraft lignin are 6.14 years and 22.96%, respectively.