Design of Ti-Beta zeolites with high Ti loading and tuning of their hydrophobic/hydrophilic character

For heterogeneous catalysts, like Ti-Beta zeolites, the control of the material properties is very important. Due to their high surface area, large 12-ring pore channels and highly active tetrahedral isolated Ti-sites, Ti-Beta zeolites are well-known catalysts for applications in the field of oxidizing alkanes, alkenes, as well as for CO2 reduction. The drawback of many state-of-the-art synthesis methods is the limitation of the maximum amount of active sites and the control of material properties like hydrophilicity and Ti loading of the zeolite. This paper reports on the impact of the synthesis method and the variation of synthesis parameters on the material properties of the Ti-Beta heterogeneous catalyst. By using characterization techniques such as XRD, FTIR, UV-DR, Ar-sorption, H2O-sorption, ICP-MS and Raman spectroscopy, the control on important material properties of the Ti-Beta zeolite are investigated. A reproducible two-step post-synthesis method has been optimized in order to prepare high loading Ti(IV)-containing Beta zeolites, of which the hydrophobicity/hydrophilicity is tunable. The optimized method allows to synthesize Ti-Beta zeolites with a very high Ti loading up to 7.4 wt% Ti with the majority in the form of isolated tetrahedrally coordinated Ti(IV) in the zeolite framework, which is a three times higher Ti loading than Ti-Beta materials synthesized by conventional hydrothermal synthesis. This high Ti loading together with the tuning of the hydrophobicity/hydrophilicity is expected to have a positive effect on the catalytic performance of Ti-Beta zeolites.