Two-step conversion of cellulose to levoglucosenone using updraft fixed bed pyrolyzer and catalytic reformer

Abstract

In this work, production of levoglucosenone, a promising biorenewable platform chemical, from cellulose was investigated using a two-step continuous process that consists of an updraft fixed bed reactor for fast pyrolysis of cellulose and a catalytic reformer for the volatiles conversion. The updraft fixed bed pyrolyzer produced levoglucosan, which was a precursor of levoglucosenone, with the yield of 38.4% on a carbon basis (%-C) at the optimized temperature of 500 °C. The yield of levoglucosenone significantly depended on the type of catalyst used for the reforming of volatiles. Acidic activated carbons prepared with sulfuric or phosphoric acid treatment showed good catalytic activity toward levoglucosenone formation, when mixed with cellulose in the catalytic pyrolysis, but were unavailable in the two-step process due to the quick deactivation by coke deposition. Supported ionic liquid (IL: 1-butyl-2,3-dimethylimidazolium triflate) phase catalysts enabled selective production of levoglucosenone independent of the support material examined (silica, γ-alumina, and activated carbon). The continuous operation was possible with the maximum levoglucosenone yield of 16.6%-C, but the IL catalysts also suffered from problems such as coke deposition and IL decomposition. The problems were quantitatively assessed in the experiments at different conditions.