Intensification of n-butyl ethanoate synthesis using ultrasound over ammonium sulphate supported on silica extracted from rice husk ash as an efficient heterogeneous catalyst

The silica extracted from rice husk ash was used as support to load ammonium sulphate ((NH4)(2)SO4) (10-40 wt.%) and ammonium sulphate supported on rice husk silica ((NH4)(2)SO4/RHS) catalysts were characterised by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and scanning electron microscope (SEM) with EDS techniques. The catalyst was further used to convert butan-1-ol to n-butyl ethanoate in an ultrasonic batch reactor. The study demonstrated the influence of ultrasound and operating parameters on the conversion. The maximum conversion of 88.77% was attained at the optimal operating conditions of temperature 353 K, molar ratio 1:2 (ethanoic acid to butan-1-ol), catalyst loading 4% (w/w), duty cycle 75% and ultrasound power 80 W. When compared with the conventional process, the reaction time was reduced by 54% in ultrasound-assisted synthesis over conventional synthesis. It has been observed that intensification benefits as it lowers reaction time for the ultrasound-assisted approach.