Catalysis Science and Engineering, Poster
Bio-Oil Upgrading by Esterification; The Case of Guaiacol and Octanoic Acid over Heterogeneous Sulfonic Acid
B. Duraki1, M. Ravi1, J. A. van Bokhoven1,2*
1Institute for Chemical and Bioenineering, ETH Z├╝rich, Switzerland, 2Paul Scherrer Institure, Switzerland
Esterification is an important reaction in the chemical industry. Biodiesel is produced by esterification of fatty acids with methanol using a solid catalyst and high temperature1. Lignin is a promising, renewable, and oxygen-rich resource for phenol and phenol-derivative compounds. Pyrolysis of lignin yields bio-oil and contains the monomers and dimers of the parent lignin. However, the properties of bio-oil are disadvantageous and contain too many compounds to afford separation2. Our idea is to chemically catch the oxygen-rich lignin monomers and react them to produce new chemicals. This can be done by esterification and acylation with another biomass resource, a long chain fatty acid.
MCM-41 functionalized with propyl-sulfonic acid moieties are efficient catalysts for guaiacol esterification with octanoic acid. The small pore MCM-41, MCM-41-PrSO3H (1.9) was found to be the best catalyst for the esterification reaction examined in this study and hence emerges as a potential catalyst which can be tested for upgrading of lignin pyrolysis bio-oils. Low sulfur leaching in the spent catalyst was a hallmark of the stability of the heterogeneous catalyst. The activity of the catalyst was about 3 times lower than that of sulfuric acid in terms of ester produced per octanoic acid. The octanoic acid conversion was similar with sulfuric acid and MCM-41-PrSO3H (1.9) catalyst.

Successfullysynthesis of MCM-PrSO3H without destroying the structure can be used for bio-oil upgrading. Low sulfur leaching, high activity and easy separation makes its use unavoidable.

[1] Shih-Yuan Cet al, Applied Catalysis B: Environmental2007, 148-149, 344-366.
[2] Zhao Cet al, ChemCatChem2012, 4, 64-68.