Template-Free Sol-Gel Synthesis of Catalytically Active Mesoporous Titanosilicates

A template-free sol-gel technique was developed for synthesis of micro-mesoporous and mesoporous titanosilicates using commercially available raw materials such as mixture of oligomer esters of orthosilicic acid (ethylsilicate-40) and an aqueous-alcoholic solution of tetraethoxysilane. The influence of pH of the reaction mixture on the characteristics of the porous structure of titanosilicates prepared by the sol-gel technique was investigated. pH was varied between 3 and 10 to prepare samples of the amorphous structure with different textural parameters: specific surface area 320–740 m²/g, micropore volume 0,04–0,15 cm³/g, mesopore volume 0–0,92 cm³/g. The mesoporous titanosilicate prepared at variable pH showed the maximal catalytic activity to oxidation of 4-tert-butylphenol (TBF) with aqueous hydrogen peroxide solutions (the conversion of 4-tert-butylphenol was 45 wt.%, selectivity for 4-tert-butylpyrocatechol 66 wt.%; conditions: 10 wt.% titanosilicate, TBF/H₂O₂ = 1/2, 75 °C, 1 h).

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