A new generation of SBA-15, plugged SBA-15, was initially synthesized in 2002 using extra silica precursors (Si/organic template molar ratios ≈ 80–140) in the gel mixture. The plugged SBA-15 materials possess short cylinders (length ≈ 20–100 nm), which are connected to neighbors by constricted entrances (windows) through the central axis. The gas adsorption–desorption isotherms of plugged SBA-15 materials present unique hysteresis loop Type H5 classification identified by IUPAC in 2015, which is related to certain pore structures containing open and plugged mesopores. The plugged SBA-15 has been used to support various types of catalysts, including metal complexes, metal nanocatalysts, and active metals by the incorporation in their framework demonstrating excellent (enantio)selectivity, stability against coke, and thermal stability. The plugged SBA-15 materials bear the other unique properties of the ship-in-the-bottle synthesis of, e.g., metal complexes that confine homogeneous catalysts, which is not possible by conventional SBA-15 due to leaching. In this mini-review, the challenges and progress of the synthesis in controlling the plugging and incorporation of metals and organic moiety in their framework, characterizing the short mesochannel dimensions (window and length sizes) by several advanced techniques and applying plugged SBA-15 materials in heterogeneous catalysis for challenging reactions, has been discussed.

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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.