Solid acids in liquid phase esterification

Abstract

Catalytic activity of different protonated zeolites such as HY, Hβ, HZSM5 and sulfated oxides such as SO₄^2-/Al₂O₃, SO₄^2-/SiO₂<i>, </i>SO₄^2-/ZrO₂ in the esterification of propionic acid with various alcohols (C₁-C₅) over solid acids as catalysts has<i> </i>been investigated. The catalysts have been characterized for their total surface acidity, BET surface area and sulfur content<i> </i>in sulfated catalysts. Catalytic activity studies have been conducted in liquid phase under refluxing conditions. A systematic study has been made to find out the effects of nature of alcohols, amount of the catalyst and the duration of reaction in the synthesis of propionate esters. Product analysis has been done quantitatively by gas chromatography and qualitatively by GC-MS. All the catalysts have been found to be active towards the formation of propionate esters as the major reaction product. A good correlation between the concentration of acid sites and the catalytic activity of the catalysts has been observed.