Pilot Scale Electrolysis of Peroxodicarbonate as an Oxidizer for Lignin Valorization

A pilot scale plant at Technology Readiness Level (TRL) 6 comprising an electrochemical ex-cell continuous production of sodium peroxodicarbonate and a thermal depolymerization plug flow reactor for kraft lignin conversion is established. Due to the labile nature of the "green" oxidizer peroxodicarbonate, special attention must be paid to the production parameters in order to optimize its use. A simplified design model describing steady-state and transient operations is formulated and finally validated against experimental data from the electrolysis setup. Design trade-offs are visualized, and their impact on specific energy consumption is evaluated. The pilot plant was operated for a 20-month period for more than 1200 h on-stream. Optimized process conditions result in vanillin yields of 8 wt % and thus prove the successful scale-up.