Post-synthesis treatment for improving zeolite coating stability

Zeolite A and zeolite X coatings prepared by using the substrate heating method were coated by polyacrylic acid films in order to improve their stabilities. Various synthesis conditions were used to obtain coatings of different thicknesses. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-Transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) were used to characterize the materials prepared. The mechanical and thermal stabilities of the coatings were determined by the application of consecutive ultrasonic treatments and heating/cooling cycles, respectively. It was observed that the post-synthesis treatment applied to zeolite coatings improved the stabilities of these materials. The thin polyacrylic acid films were well integrated with the zeolite crystals and did not lead to any problem regarding water desorption from the samples investigated.