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The effect of the modification of aluminum oxide with silicon oxide on the stability of fine parti cle γ and δ Al 2 O 3 phases upon heat treatment in the wide temperature range of 550-1500°C was studied. It was found that the γ and δ Al 2 O 3 phases modified with silica are thermally stable up to higher temperatures than pure aluminum oxide. This is due to changes in the real structure of the modified samples, specifically, an increase in the concentration of extensive defects stabilized by hydroxyl groups bound to not only alumi num atoms but also silicon atoms. It is likely that Si-OH groups, which are thermally more stable than Al⎯OH groups, stabilize the microstructure of γ and δ Al 2 O 3 to higher temperatures, as compared with alu minum oxide containing no additives. Simultaneously, an increase in the thermal stability of the modified samples is accompanied by the retention of a high specific surface area and a developed pore structure at higher treatment temperatures.

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Catalytic properties of Ti-containing porous solids were compared in the oxidation of 2,3,6-trimethylphenol (TMP) with H 2 O 2 to produce 2,3,5-trimethyl-1,4-benzoquinone (TMBQ, vitamin E key intermediate). Mesoporous titanium-silicates with di(oligo)nuclear Ti centers, metalorganic framework MIL-125 and amorphous TiO 2 demonstrated 100 % selectivity toward TMBQ. Titanium-silicates prepared by evaporation-induced self-assembly revealed superior performance in terms of product yield and catalyst reusability.