Construction of Boron-Promoted Ti Active Centers in Titanosilicates for Selective Oxidation Reactions

The development of efficient oxidation reactions utilizing titanosilicate/H₂O₂ catalytic systems holds significant importance for the green production of bulk and fine oxygenated chemicals. Precisely tailoring the microenvironment of Ti active centers in titanosilicates plays a key role in enhancing their catalytic oxidation performance. In the present study, a novel titanium active center was constructed for the first time through the high-temperature treatment of boron-containing titanosilicates under a hydrogen atmosphere. The Ti-O-B bonds in zeotype borosilicotitanate with MWW topology (Ti-B-MWW), confirmed by high-resolution time-of-flight mass spectrometry, undergo cleavage during H₂ treatment, resulting in the formation of "open" Ti species surrounded by tricoordinated boron species. These unique Ti active centers promoted by boron species in the vicinity exhibited enhanced catalytic performance compared to both conventional "open" and "close" Ti active sites in selective oxidation reactions, not only due to the inherent open structure-induced lower H₂O₂ activation barrier but more importantly to the lower product desorption energy related to adjacent boron. This study demonstrates that the heteroatoms in proximity to Ti active sites significantly influence the catalytic behavior of titanosilicates, offering a new strategy for developing novel zeolite catalysts.