Preparation of extruded catalysts based on TS-1 zeolite for their application in propylene epoxidation

In this work, the extrusion process of titanium silicalite (TS-1) zeolite has been investigated and optimized in order to obtain materials with convenient catalytic and mechanical properties for their application in the propylene epoxidation with hydrogen peroxide using fixed bed reactors. Thereby, a variety of TS-1 samples were prepared having particle sizes comprised between 0.2 and 0.7 μm. It has been observed that the increase of the zeolite particle size affects negatively the mechanical strength of the extrudates. Likewise, a variety of inorganic binders such as clays or inorganic silica have been explored; the best results in terms of minimizing the H2O2 decomposition being obtained with sepiolite. Moreover, three extrusion methods and different TS-1/inorganic binder mass ratios were investigated in order to achieve an extruded material with satisfactory mechanical strength. The optimum extruded catalyst was prepared using a TS-1/sepiolite mass ratio of 60%/40% and employing ultrasounds during the paste preparation. Finally, the catalytic activity of the optimum extruded TS-1 zeolite has been evaluated for the propylene epoxidation reaction using a fixed bed reactor, achieving conversion and H2O2 selectivity values close to 97% and 80%, respectively.