Abstract:
Nanosheet HZSM-5 film vertically grown on the substrate with the tailorable
macro- and meso-pores between the layers of nanosheets is hydrothermally synthesized
by seed-assisted secondary growth method. The as-prepared nanosheet HZSM-5 film
(ZN-5) exhibits reaction rate enhancement up to 312% in catalytic cracking of n-dodecane
as well as twice light olefins selectivity compared with conventional HZSM-5 (CZ-5),
ascribed to the better mass transfer of reactants in the hierarchical porous
structure and the ultra-thin b-axis pores of nanosheets. Thiele modulus (¦Õ) of CZ-5
(5.44) was four-times higher than that of ZN-5 (1.02), evidencing a higher mass
transfer limitation in bulky crystals. In addition, the introduction of
silicalite-1 crystals effectively enhanced the adhesive strength,
zeolite loading as well as the continuity of films. This study
suggests a possibility to the synthesis of nanosheet zeolite film that could
find great potential applications as structured zeolite catalysts in the diffusion limited and
acid related catalytic
processes.
