(560ar) Catalytic Conversion of Cellulose into Levoglucosenone Using Homogenous Brønsted Acid Catalysts in Polar Aprotic Solvents in a Flow Reactor

Levoglucosenone (LGO) is a high value anhydro – sugar used in the synthesis of pharmaceutics, renewable solvents, polymers; and other specialty and high value chemicals. LGO is commonly produced from the pyrolysis of cellulose in low yields (12-20%). Huber and coworkers reported yields of LGO of up to 51% from cellulose dehydration using 20mM sulfuric acid (H₂SO₄) as catalyst in polar aprotic solvents such as tetrahydrofuran (THF) in a batch reactor.¹ Recently, our research group in collaboration with Huber’s at the University of Wisconsin – Madison studied the production of LGO from cellulose in a batch reactor using lower concentrations of sulfuric acid combined with solid acid catalysts in (THF). The study found similar LGO yields to those obtained with higher concentrations of sulfuric acid. Itwas also found that the accumulation of water during the reaction of cellulose to LGO in a batch reaction system promotes the formation of other products over LGO. Here we show the results of using a flow reactor instead of a batch one for the dehydration of cellulose to LGO using different Brønsted acid catalyst such as H₂SO₄, 1-propanesulfonic acid and phosphoric acid in polar aprotic solvents such as γ-valerolactone, THF and acetone. We show the effect of the reaction temperature and the catalyst concentration on the LGO yield. We demonstrate that using different sources of cellulose has an effect on the yield of LGO. Also, we show that the crystallinity of the cellulose has a significant effect on the production of LGO. We demonstrate that LGO can be effectively produced from cellulose using Brønsted acid catalysts in polar aprotic solvents using a flow reactor.

1. Cao, F.; Schwartz, T. J.; McClelland, D. J.; Krishna, S. H.; Dumesic, J. A.; Huber, G. W. Dehydration of cellulose to levoglucosenone using polar aprotic solvents. Energy & Environmental Science 2015, 8 (6), 1808-1815.