In-Situ Growth of Embryonic TS-1 on Amorphous Silica via Steam-Assisted Crystallization: Correlation of Structural Properties and Catalytic Performance of Embryonic, Crystalline, and Amorphous Titanosilicate Catalysts

In-situ growth of supported embryonic TS-1 zeolite (<10 nm) on a silica support was achieved by steam-assisted crystallization (SAC). The use of low amounts of TPABr and steam at a moderate temperature of 130 °C was the key factor to control partial transformation of silica into supported embryonic TS-1. Compared with the reference crystalline TS-1, supported embryonic TS-1 exhibits a higher activity in dibenzothiophene (DBT) oxidation (TOF: 8–275 h–1 vs 2.7–160 h–1 at 30–98 °C), a higher resistance to poisoning by nitrogen-containing compounds, and a higher selectivity (>97%) in the productive utilization of the oxidant in DBT oxidation. The activity of the amorphous titanosilicate (TOF: 21.2–210 h–1 at 30–80 °C), the solid precursor of the SAC process, was higher than that of the embryonic and the crystalline TS-1. The analysis of the structural properties–catalytic performance of these catalysts showed an improved accessibility to defective Ti active sites “Ti(OH)(OSi)3” with higher catalytic activity. The results of this study should be encouraging to unearth many other active amorphous catalysts with the potential of industrial application.