Adding value to waste glycerol to produce renewable fuels and chemicals

Abstract

This thesis presents the results of research into the value addition of glycerol, as a by-product from biodiesel production. A number of different catalytic systems were developed involving two different pathways of value additions; (1) the esterification of glycerol with acetic acid to produce acetin esters, and (2) the transesterification of glycerol with dimethyl carbonate to produce glycerol carbonate. In the esterification of glycerol with acetic acid, two catalytic systems were developed. A homogeneous system which used nitrogen based Brønsted-acidic ionic liquids and a heterogeneous system which used tin-exchanged tungstophosphoric acid supported on K-10 montmorillonite clay. In the homogeneous system a number of ionic liquids were tested in the reaction, with n-methyl-2-pyrollidinium hydrogen sulphate found to be the most active. The reaction conditions were optimised using a design of experiments approach, and the reusability of the catalyst was examined. In the heterogeneous system the effect of heteropolyacid loading and level of metal substitution were investigated. 20 wt% Sn1DTP/K-10 was found to be the most active catalyst, with the effect of reaction parameters and catalyst reusability examined using this catalyst. This catalyst was also used in preliminary continuous flow investigations. In the transesterification of glycerol with dimethyl carbonate to produce glycerol carbonate a series of metal oxide supported sodium aluminate catalysts were prepared. The effect of preparation method (wet impregnation vs. mechanochemical preparation), metal oxide support and loading of sodium aluminate. Of all the catalysts prepared 20 wt% sodium aluminate on alumina was found to be the most stable catalyst. The effect of calcination temperature on this catalyst was also investigated with increasing calcination temperature resulting in decreased initial catalytic activity but increased catalyst reusability.

Date of Award	Dec 2022
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	The Bryden Centre & Special EU Programmes Body
Supervisor	Marijana Blesic (Supervisor) & Haresh Manyar (Supervisor)