In situ synthesis of binderless ZSM-5 zeolitic coatings on ceramic foam supports

In situ synthesis of binderless ZSM-5 zeolite coatings on ceramic foam supports was studied. The effects were investigated of the rotation of the autoclaves during synthesis, the reaction mixtures SiO2/Al2O3 and dilution ratios, the reaction mixture-to-support surface area ratio, the synthesis temperature and time as well as the composition of the support material (α-Al2O3, SiC/Al2O3 and ZrO2/Y2O3 foam). X-ray diffraction patterns showed highly crystalline ZSM-5 structures superposed on the ceramic foam carrier pattern. The deposition of ZSM-5 was quantified by measuring mass increase and BET surface of the samples. Uniform and continuous ZSM-5 coatings with overall specific surface areas of up to 200 m2/g were obtained. SEM micrographs showed coffin-like, partly intergrown crystals of 5–10 μm that appeared to be attached firmly to the support.