Heterolytic cleavage of cellulose glycosidic bonds enables the depolymerization and deconstruction of long-chain glucan biopolymers to small molecules for fuels and chemicals. The homogeneity of cellulose ether linkages (Î², 1-4) allows for a common activating mechanism leading to rapid chain scission. As originally proposed by Shafizadeh and co-workers
, the activating mechanism of cellulose dominates the overall chemistry at 500 Â°C. In this work, we reveal the existence of two kinetic regimes of intra-chain cellulose activation transitioning at 467 Â°C
. The high temperature activation mechanism associated with energy technologies (e.g. gasification, pyrolysis) exhibits high activation energy (~53 kcal/mol) and pre-exponential (1016
) consistent with the mechanism of concerted transglycosylation
. The insertion of alkaline earth metals including calcium substantially enhance the rate of high temperature activation, by lowering the transition temperature at which this mechanism dominates
. Measured apparent activation energy, pre-exponential, and rate expressions are reported for calcium catalysis consistent with computations of cooperating metal atoms.
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