Synthesis and characterization of aluminium incorporated mesoporous KIT-6: Efficient catalyst for acylation of phenol

Mesoporous Al-KIT-6 materials with Si/Al ratios of 20, 30, 40, 50, 100 and 150 were synthesized hydrothermally and were characterized by X-ray diffraction (XRD), nitrogen sorption isotherm, Fourier transform infrared spectroscopy (FT-IR), pyridine-adsorbed DRIFT-IR, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM). The surface area of the catalysts decreased with the increase of aluminum content in Al-KIT-6. The high quality of cubic Ia3d silica product was judged by HR-TEM. The nature and the strength of the acid sites of the catalysts were probed by pyridine-adsorbed DRIFT spectra. The vapor phase acylation of phenol with acetic acid was carried out over all the materials to evaluate their catalytic activity. All the catalysts were found to be active in the formation of phenyl acetate with high selectivity. The formation of coke was not significant at any temperature. The time-on-stream study revealed steady conversion of phenol (80%) and steady selectivity to phenyl acetate (90%) during the entire period. The activity of the catalysts followed the order: Al-KIT-6 (20) > Al-KIT-6 (30) > Al-KIT-6 (40) > Al-KIT-6 (50) > Al-KIT-6 (100) > Al-KIT-6 (150). The selectivity of phenyl acetate was almost the same over all the catalysts, but the selectivity of o-HAP over Al-KIT-6 (40) was slightly lower than others. The effect of reaction parameters was examined exclusively over Al-KIT-6 (40).