Aromatic hydrocarbons rich bio-oil production from Miscanthus pyrolysis by coupling torrefaction and MoO3/ZSM-5 dual catalysis process

Abstract

The valorization of Miscanthus pyrolysis by coupling torrefaction and MoO3/ZSM-5 dual catalysis process was studied to generate the aromatic hydrocarbons rich bio-oil, biochar, and combustible gas. With the optimal conditions of torrefied Miscanthus at 280 °C, MoO3/ZSM-5 catalysis process converted 24.17 % bio-oil, 30.27 % biochar, and 45.56 % gas. The coupled system accessed bio-oil phase deoxygenation by reducing the oxygen-containing compound content to 6.27 %. The aromatic yield reached 91.38 %, with an outstanding benzene, toluene and xylene (BTX) selectivity of 52.24 %. Isolating investigations revealed that torrefaction declined the oxygen content of Miscanthus to 5.24 %, increasing their calorific value and promoting subsequent catalytic pyrolysis through deoxygenation. When only using the ZSM-5 catalyst, the increase in torrefaction temperature enhanced aromatic hydrocarbon compounds conversion in the bio-oil, leading to a boost in their content from 55.01 % to 75.97 %. Correspondingly, MoO3 promoted deoxygenation, decreased the ketone content from 40.4 % to 21.92 %, and inhibited the generation of aldehydes. The combination of MoO3 and ZSM-5 with torrefaction delivered a superimposed effect on yielding aromatic hydrocarbons and BTX, which allowed a promising product upgrading method for obtaining high-quality bio-oil.