Preparation, characterization, and application of ordered mesoporous S2O82-/ZrO2-SiO2 with high specific surface area

摘要

A series of ordered mesoporous S2O82-/ZrO2-SiO2 (OMSZS) solid superacids with different calcination temperatures (400-650 degrees C) was synthesized using zirconium n-propoxide and tetraethyl orthosilicate as the raw materials and P123 as a structure-directing agent by solvent evaporation-post-dipping method. Transmission electron microscopy and small-angle X-ray diffraction results showed that the OMSZS were all ordered. The nitrogen adsorption results indicated that the specific surface area of OMSZS could reach up to 331-385 m(2)/g, whereas the average pore diameters were in the range of 3.1-3.2 nm. The pyridine infrared results mainly displayed Lewis acids, and the ammonia (NH3)-temperature programmed desorption characterization showed that the NH3 desorption of the OMSZS calcined at 550 degrees C was 61 cm(3)/g STP. The catalytic performance of the OMSZS was investigated by the transesterification reaction of waste frying oil and methanol. The yield of fatty acid methyl ester could reach up to 94% at 200 degrees C reaction temperature for 6 h. After repeated use for four times, the catalyst still featured good activity and the yield was 78%.