Synthesis and characterization of self-bonded ETS-4 and ETS-10 pellets

Self-bonded pellets of ETS-4 and ETS-10 zeolites are prepared by hydrothermal synthesis at 190 °C from gels of compositions xNa2O–0.6KF–yTiO2–1.28HCl–1.49SiO2–39.5H2O with 0.5 ⩽ x ⩽ 2.5 and 0.1 ⩽ y ⩽ 0.4. Two methods are used: the dry gel and the hydrated gel methods. The pellets produced by the hydrated gel methods have a higher crystallinity and in the case of ETS-10 no binder is required to hold strongly together the individual crystallites. The mechanical resistance is ca. 20–25% higher for these pellets with respect to those prepared by the dry gel method. The crystallization rate is also higher and more regular crystals are formed.