Levoglucosenone production by catalytic fast pyrolysis of cellulose mixed with alkali metal-doped Keggin heterpolyacid salt

Abstract

Levoglucosenone (LGO) has shown a promising potential in the application of the sustainable chemistry. In this work, alkali metal-doped phosphotungstic acids, M2.5H0.5PW12O40 (M = Li, Na, K, Rb and Cs), were synthesized and employed for catalytic fast pyrolysis of cellulose to selectively produce LGO. The results show that levoglucosan, the main precursor of LGO, was produced with a yield of 33.5 wt% by non-catalytic pyrolysis of cellulose, while LGO by catalytic fast pyrolysis of cellulose is mainly regulated by the strong/weak acid sites of the M2.5H0.5PW12O40. Increasing the atomic radius of the alkali metals from Li to Cs doping to phosphotungstic acid led to an increase of LGO yield, attaining to 15.6 wt% at 300 °C over Cs2.5H0.5PW12O40 due to a high strong/weak acid site ratio. In addition, LGO yield was further enhanced to 19.2 wt% over (NH4)2HPO4 modified Cs2.5H0.5PW12O40 as a result of an increase of moderate strong acid sites. This study provides a potential method for LGO production by catalytic pyrolysis of cellulose.