Hollow zeolite-encapsulated Fe-Cu bimetallic catalysts for phenol degradation

Highly dispersed Fe-Cu bimetallic oxide nanoparticles were successfully encapsulated in hollow Silicalite-1 single crystals (Fe₂O₃[sbnd]CuO@Hol S-1) by tetrapropylammonium hydroxide (TPAOH) hydrothermal treatment with an “impregnation-dissolution-recrystallization” process. Due to the Fe-Cu bimetallic interaction compared with single iron oxide, Fe-Cu bimetallic oxide exhibits a higher dispersion with the particle size decreasing from ∼11.3 nm to ∼3.7 nm. For aqueous phenol degradation, the Fe₂O₃[sbnd]CuO@Hol S-1 catalyst exhibits high activity attributed to the enhanced transport of reactants/products in the short microporous channels (20 nm) and the small metal oxide particle size. Interestingly, the particle size of encapsulated Fe₂O₃[sbnd]CuO (3.7 nm) is larger than that of zeolite micropore (0.53 nm), which helps preventing the leaching of metal oxide that is a significant problem for conventional supported Fe catalyst in this reaction.