Lignin catalytic depolymerization for liquid fuel and phenols by using Mo/sepiolite catalysts calcined at different temperature

Obtaining clean and green liquid fuels by catalytic conversion of lignin over eco-friendly and economical heterogeneous catalyst is one of the potential technologies for effectively relaxing energy and ecology crisis. Mo/Sepiolite (SEP) exhibited broad prospects for lignin catalytic depolymerization (LCD) and its synthesis parameters especially for calcination temperature (CT) presented significant effect for reactive performance. Herein, Mo/SEP catalysts were prepared by an incipient-wetness impregnation method and calcined at different temperatures. Its catalytic activity for LCD under supercritical ethanol were systematically investigated. Various characterization results revealed CT mainly resulted in the transformation of Mo species from (NH4)(6)Mo7O24 center dot 4H(2)O to MoO3 and subsequently to Al-2(MoO4)(3) with CT augmented from 200 degrees C to 600 degrees C. Then, the variation of Mo species affected the amount of active Mo5+ species and distribution of B/L acidic sites on the Mo/SEP surface. When calcined at 400 degrees C, Mo/SEP presented optimal configuration among active metal species, acid amount and form. Therefore, Mo/SEP-400 displayed the highest lignin oil (LO) yield (80.29%) and yielded 65.74% of petroleum ether soluble products at 310 degrees C for 4 h under N-2 atmosphere. The produced LO had the higher HHV value of 35.53 MJ/kg and contained abundant phenolic monomer with the yield of 106.1 mg/g (lignin). According to the catalyst structure analyses and liquid product composition, the possible evolution mechanism of Mo species and the pathway of lignin conversion over Mo/SEP-400 under supercritical ethanol was proposed.

Automated summary

In this study, Mo/SEP catalysts were prepared by an incipient-wetness impregnation method and it was found that calcination at 400 degrees Celsius exhibited optimal catalytic activity, resulting in the highest lignin oil yield.