Beneficial role of SiO2 plugging in AlCl3 heterogenized plugged hexagonal templated silica (PHTS) for the isopropylation of m-cresol

Plugged hexagonal templated silica (PHTS – a modified SBA-15) has been synthesized using triblock co-polymer as template and tetraethyl orthosilicate as silica source under hydrothermal conditions and AlCl3 has been heterogenized on it which is proven to be an efficient heterogeneous catalyst for the isopropylation of m-cresol. The activity of AlCl3 heterogenized on SBA-15 has also been tested for the purpose of comparison. The higher activity of Al–PHTS over Al–SBA-15 has been attributed to the presence of more number of medium strength acid sites formed by the plugging of silica and higher AlCl3 heterogenization in the former catalyst as observed from 27Al MAS NMR and temperature programmed desorption of NH3.