Evaluation of Primary Reaction Pathways in Thin-Film Pyrolysis of Glucose Using 13C Labeling and Real-Time Monitoring

There recently has been progress on the fundamental understanding of fast pyrolysis as a promising strategy for biorenewable energy. An example of this progress is the dissection of bulk-sum models into individual molecular reactions as an effort to explain and predict the product yields in biomass pyrolysis. However, rigorous efforts have been scarce to experimentally validate each molecular reaction in pyrolysis. In this work, we evaluate molecular reaction mechanisms in the pyrolysis of glucose labeled with C-13 on the C-1, C-3, or C-6 position. We adopt a novel experimental system that we have recently developed to study isothermal reaction kinetics with a very short reactor residence time (similar to 0.2 s) in virtual real time, which is ideally suited to correlate the results with primary reactions in theoretical modeling. We were able to support the previously proposed primary reaction for C4H8O4 (erythrose) but reject those for C3H6O3 (dihydroxyacetone and glyceraldehyde) and C3H6O2 (acetol). Alternative reaction pathways proposed to explain our data suggest that retro aldol reaction is much more efficient than Grob fragmentation in general.