by Lu Zhang, Felipe Anaya, K. Chen, J. Kelsey,Jefferey White, Steven Crossley, LiangLiang Huang, Rolf Jentoft, and Daniel Resasco.
Work was performed at: The University of Oklahoma and Oklahoma State University
Most commercial zeolites exhibit silanol-terminated defects (mesopores, external surface). These defects make the zeolite susceptible to liquid water attack at moderate temperatures. We have observed dramatic enhancement in stability when the zeolites are functionalized with hydrophobic molecules.
Zeolites are very effective materials for upgrading of biomass-derived compounds. However, in many cases, upgrading has to be conducted in condensed phases. As a result, zeolites should be able to tolerate exposure to hot liquid water. We have demonstrated that silylation of defective zeolites not only enhances stability, but also retains the Brønsted acid sites, keeping the zeolites active.
Figure: Attack of zeolite structure by water at 200 C only occurs when there is condensed water present and the zeolite contains silanol-terminated defects