Direct Thermochemical Liquefaction

Esterification

Esterification of Bio-oil

A silica-included catalyst with Wells-Dawson structure was used for esterification of the whole fast pyrolysis of bio-oil originating from beech wood with n-butanol. Wells-Dawson solid acid esterification properties were compared with the homogeneous liquid acid catalysis (sulphuric acid). The use of solid acid catalyst significantly changes the esterification products compared to sulphuric acid, promoting production of: propanoic acid butyl ester, propanoic acid 1-methyl ester, 2-butenoic acid butylester and butanoic acid anhydride. Figure 1 shows the raw bio-oil and the distilled esters.

The majority of carboxylic acids were efficiently upgraded to neutral esters at yields up to 90 wt.% and the conversion yields were similar with Wells-Dawson solid acid as sulphuric acid. The product slate however was significantly different as shown in Figure 2. These esters have a potential as additives to diesel miscible (bio)fuels as well as chemicals in their own right.

Figure 1: Esterification reagents and products.

The majority of carboxylic acids were efficiently upgraded to neutral esters at yields up to 90 wt.% and the conversion yields were similar with Wells-Dawson solid acid as sulphuric acid. The product slate however was significantly different as shown in Figure 2. These esters have a potential as additives to diesel miscible (bio)fuels as well as chemicals in their own right.

Figure 2: The solid acid catalyst significantly changes the esterification products compared to sulphuric acid.