Activated clay supported heteropoly acid catalysts for esterification of acetic acid with butanol

The esterification of acetic acid with primary (n-), secondary (sec-) and tertiary (ter-) butanol catalyzed by supported heteropoly acids (HPAs), such as dodecatungstophosphoric acid (TPA), dodecatungstosilicic acid (TSA) and dodecamolybdophosphoric acid (MPA) on acid activated Bentonite (AT-GMB) matrix have been carried out. The 20% loaded TPA on AT-GMB showed the highest catalytic activity. The conversions of different alcohols into the corresponding esters decrease in the following order: n-butanol > sec-butanol > ter-butanol. The selectivities for the corresponding esters are nearly 100%. The catalysts were characterized by surface area, thermal analysis, XRD and FTIR spectroscopy. The reusability study shows that the catalysts are stable and active.

Research highlights
► Heteropoly acids supported on modified Bentonite effectively catalyse esterification.
► The dodecatungstophosphoric acid containing catalysts showed the highest efficacy.
► High surface area and acid sites of the catalysts influence the catalytic activities.
► The catalysts can be regenerated and reused for several runs.