Alkyl and alkoxy phenols are desirable products from the catalytic depolymerisation of lignin. In this work, ex-situ catalytic pyrolysis of Etek lignin in presence of Na, Ce, NiCe, MgCe, Fe and FePd on ZrO2 was studied. The largest combined yield of monomeric phenolics and alkylphenols was produced by Na/ZrO2 catalysts. A parametric study of the most promising Na/ZrO2 then resulted in using a catalyst:lignin ratio of 3:1 at 500 °C as the best option, enhancing at 17.5 wt% the recovery of total phenolics including 6 wt% alkyl phenols, which is equivalent to 27.8 wt% and 9.5 wt% of the starting lignin in Etek lignin waste. The study of the catalyst basicity indicates that the mild basicity of Na/ZrO2 was mostly responsible for the enhanced mono phenols recovery. Due to formation of thermally stable Na2CO3 during pyrolysis, successful Na/ZrO2 regeneration requires temperature of 900 °C or higher.
- Sodium zirconate