tert-Butylation of toluene with tert-butyl alcohol over immobilized titanium species on the Al-MCM-48

A series of Ti-Al-M48 (M48 stand for MCM-48) samples with different titanium species loadings were prepared by immobilization method. Their physical chemical properties were characterized by XRD, liquid N-2 adsorption-desorption, Py-IR, NH3-TPD and UV vis DRS techniques, and their catalytic performances were investigated in the tert-butylation of toluene with tert-butyl alcohol in a 100 ml stainless steel autoclave equipped with a magnetically driven impeller. The Ti-Al-M48 samples have a large BET surface and ordered mesoporous structure. Although the titanium species loading is the same, the 4% Ti-Al-M48 sample has a larger acid amount than the 4% Ti/Al-M48 sample prepared by impregnation. The Py-IR and UV vis DRS spectra revealed that the isolated TiO4 tetrahedra by isomorphous substitution into the Al-M48 network have Lewis acidity. The 4% Ti-A1-M48 has a higher catalytic performance than other samples and the influence of reaction conditions on the tert-butylation of toluene was discussed. The conversion of toluene is 47.5% and the selectivity of p-tert-butyltoluene is 77.2% at the molar ratio of tert-butyl alcohol to toluene 2, the weight ratio of toluene to catalyst 8, reaction temperature 453K and reaction time 4 h. The 4% Ti-Al-M48 sample shows high stability, and toluene conversion 43.7% and p-tert-butyltoluene selectivity 78.4% can be obtained even though after repeated reaction for 3 times. (C) 2015 Elsevier B.V. All rights reserved.