Heterogeneous acid catalysts for acetylation in glycerol
(2012)
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- Authors
- Supervisors
- Gaigneaux , Éric
- Abstract
- (en) Glycerol is a low value molecule obtained as a sub-product from the manufacture of first generation biodiesel. The surplus of glycerol can be revaluated by its acetylation, forming high value molecules (monoacetin, diacetin and triacetin) which can be used in the polymer industry and as a biodiesel among other possibilities. This work provides a comparative study of the catalytic performances of a large scope of acid solids in the esterification of acetic acid with an excess of glycerol. Aluminium containing formulations (niobium oxide supported on commercial silica-alumina, aluminium phosphate) presented an inhibitory effect probably due to the amphoteric character of aluminium-bonded hydroxyl groups and the presence of basic sites where the limiting reagent (acetic acid) could be strongly adsorbed being unavailable for the reaction. Tungstated zirconia samples presented an inert behaviour, due to the deactivation of active sites by strong adsorption of water or glycerol. Tungstophosphoric acid immobilised by sol-gel technique in zirconia and silica, presented a high resistance to leaching. The strong interaction between the heteropolyacid and the matrixes led, however, to the lowering of the heteropolyacid acid strength, resulting in an absence of catalytic activity. Sulphated zirconia synthesised by sol-gel showed good catalytic activity. The lower the density of acid sites, the higher the catalytic activity. Nevertheless, these solids were undesirably deactivated due to sulphur leaching, thus also bringing an undesired contamination of the final products. Commercial ion exchange resins with strong Brønsted acid sites also exhibited very high catalytic performances. The lower the crosslinkage, the higher the resin swelling in the reaction medium, and thus the higher the catalytic activity. These solids were recyclable and active even in presence of water.
- Affiliations
Citations
Dosuna Rodríguez, I. (2012). Heterogeneous acid catalysts for acetylation in glycerol. https://hdl.handle.net/2078.5/157915