Ag-doped M2O3 nanoflakes as effective catalyst for lignin liquefaction in supercritical methanol medium

Solid biomasses can be exploited as an effective source of energy if they can be converted into liquid and gaseous fuels. In this study, highly crystalline Ag–Mn2O3 nanoflakes are introduced as effective catalyst for cracking of lignin into alcohols in supercritical methanol medium. The introduced catalyst was synthesized by a sol–gel process. Typically, mixing of manganese acetate, silver nitrate and citric acid solutions led to form a continuous gel when the pH was kept at 7. Drying, grinding and calcination (at 600 °C) of the obtained gel resulted in producing Ag-Mn2O3 nanoflakes. The utilized XRD, SEM, FE-SEM and TEM analyses affirmed the concluded structure and morphology. The introduced inorganic nanostructure could successfully catalyze degradation of lignin into liquid alcohols when the solid biomass was catalytically treated in an autoclave reactor in presence of methanol at 180 °C. The experimental results indicated that maximum lignin dissolution of 42.5 wt% can be obtained when the catalyst content is kept at 17 wt% and treatment time of 2 h. Overall, the present study opens new avenue for the stable ceramic catalysts for solid biowastes conversion into valuable products.