Synthesis and evaluation of ZSM-5 films on cordierite monoliths

摘要

Well-defined ZSM-5 films were prepared on cordierite monoliths using the seed film method.The monoliths were seeded with silicalite-1 seeds and hydrothermally treated either at 75 or at 150 deg C in a single or several steps.By adding sodium hydroxide to the solution,the aluminum concentration in the zeolite increased.Consequently,films with different Si/Al ratios were prepared.The film thickness could be controlled from 110 nm to 9 mum.Multi-step synthesis was used to prevent bulk crystallization and ultrasound treatment was found to be beneficial (in order) to remove sedimented crystals on the top of the coatings.The zeolite-coated monoliths were active for p-xylene isomerization,and the test results indicated that the films became less deactivated than the films prepared on alumina beads.