Kinetic Analysis on Deactivation of a Solid Bronsted Acid Catalyst in Conversion of Sucrose to Levulinic Acid

A solid Bronsted acid (Amberlyst-36) was used as a catalyst in the formation of levulinic acid from sucrose in aqueous solutions. Its rapid deactivation was investigated and simulated. Two major catalyst deactivation mechanisms were identified: (a) loss of protons due to ion exchange with cations and (b) blocking of the catalyst surface or active sites by byproducts. The catalyst activity declined with the accumulation of the byproducts, whereas the effect of ion exchange was quite complicated. The catalyst actually exhibited an increased activity with a small extent of ion exchange, because the free protons had a higher activity than those associated with the solid matrix. In repeated use, however, the solid catalyst lost most protons and activity. A first-order kinetic model was modified to characterize the deactivation mechanisms that provides a good simulation of the complicated performance of the solid catalyst in sugar solutions.