Economic analysis of vanillin production from Kraft lignin using alkaline oxidation and regeneration

Lignin conversion to vanillin is one of the promising routes for lignin valorization. This study presents an economic analysis for the conceptual design of vanillin production from 10 t/h Kraft lignin. The vanillin plant includes alkaline oxidation of lignin with NaOH, ultrafiltration, chromatographic separation, and crystallization to purify vanillin. A boiler for the combustion of waste lignin was used to supply steam required for oxidation reactions and water evaporation. Sodium carbonate (Na2CO3) formed in the combustor was regenerated into NaOH using lime. The heat network was integrated to reduce the consumption of cooling water, steam, and electricity. The plant produced 0.52 t/h vanillin with a yield of 5.2%. The return on investment (ROI) and payback period of this plant were 10.1%/year and 8.0 years, respectively. The ROI was most sensitive to the vanillin price. The desired ROI of 15%/year can be achieved with a plant size of 20 t/h lignin.