Hollow ZSM-5 with Silicon-Rich Surface, Double Shells, and Functionalized Interior with Metallic Nanoparticles and Carbon Nanotubes

Hollow ZSM-5 single crystals with silicon-rich exterior surface are prepared by a dissolution-recrystallization strategy in tetrapropylammonium hydroxide solution. Selective dissolution and exterior recrystallization cause the silicon components to migrate from the inside to outside, resulting in a regular void in the interior of the crystal, increased Bronsted acid sites and a silicon-rich external surface. The as-prepared hollow ZSM-5 exhibits excellent acid catalysis with enhanced shape selectivity, as shown in biphenyl methylation as a probe reaction, which is attributed to the silicon-rich external surface and thus the inhibition of isomerization on external surface. More interestingly, hollow ZSM-5 single crystals with double shells are successfully prepared by layer-by-layer technique followed with dissolution-recrystallization strategy. Furthermore, hollow ZSM-5 encapsulating iron and carbon nanotubes are successfully synthesized. Furthermore, hollow ZSM-5 nanosized crystals with the interior functionalized as bimetallic (oxide) nanoparticles such as CuO-Pd are also successfully synthesized.