Synthesis and catalytic application of tantalum and silica pillared porous materials from layered silicate ilerite

摘要

TaSi-ilerite materials with mesoporosity have been prepared by simultaneous intercalation of tantalum and silica precursors between the layers of layered silicate ilerite, and applied as a catalyst for the Beckmann rearrangement of cyclohexanone oxime. The intercalation of tantalum and silica into ilerite produced the pillared materials of large surface areas and gallery heights, indicating the formation of the pillared materials with porosity. Particularly, the use of silica together with tantalum as pillaring precursors significantly increased the surface areas of the pillared materials. The surface areas of TaSi-ilerite materials were 320-520 m~2/g and the gallery heights were 3.8-5.7 nm. In addition, the results from NH_3-TPD and IR measurements revealed that the pillaring of tantalum and silica into the layers of ilerite produced a broad range of acid sites and new hydroxyl groups. TaSi-ilerite materials exhibited high catalytic performance in the vapor phase Beckmann rearrangement of cyclohexanone oxime. The oxime conversions reached almost 100% at initial time and the lactam selectivities were in the range of 83-85%. The catalytic performance of TaSi-ilerite materials was due to the hydroxyl groups with the acidities from weak acidity to medium acidity.