Selective synthesis of glycerol monolaurate with zeolitic molecular sieves

The purpose of this work, is to study the selective synthesis of glycerol m onolaurate from lauric acid and glycerol as starting materials, employing c ommercial Beta, Y and Mordenite zeolites with different Si/Al ratio as cata lysts. Reaction conditions such as the stirring rate, temperature, glycerol /lauric acid ratio and catalyst mass in the reaction medium were optimized to diminish homogeneous reaction and reaction limitations due to diffusive effects. In the case of zeolite Y, an increase in glycerol monolaurate yiel d and selectivity for the monoester were verified at high Si/Al ratio. This behavior seems to be related to the presence of stronger acid sites presen t in the material with low Al content and probably also because of the high er hydrophobicity exhibited by zeolites having higher Si/Al ratio. Mordenit e catalyst, on the contrary, presented low activity and selectivity to glyc erol monolaurate, which can be attributed to the diffusional limitations im poses by the monodimensional channel system to the organic substrate access ing the inner catalyst sites, restricting the reaction to the sites present at the external particle surface. Zeolite Beta exhibited the best results as catalyst to obtain the mono-derivative, presenting selectivities higher than 60% at 20% yield. (C) 2000 Elsevier Science B.V. All rights reserved.