Biomass-derived pyrolysis oil (bio-oil) contains about 25 wt.% oxygen that reduces its energy density. The oxygenated compounds also contribute to poor stability, high density, viscosity, and acidity of the bio-oil. Hence the removal of oxygen is required in order to obtain high quality hydrocarbon fuels. Hydrodeoxygenation (HDO) is one of the most popular methods to overcome the negative properties of bio-oil, however, high hydrogen consumption and coke formation on catalyst surface potentially adds to the cost of the operation. In the present research work we investigated the synergistic effect of esterification and HDO to improve the physicochemical properties of the bio-oil. HDO of rice straw bio-oil at hydrogen pressure of 5.5 MPa over commercial Ni/SiO2-Al2O3 increased its higher heating value (HHV) from 14.6 MJ/kg to 27.5 MJ/kg while the oxygen content decreased from 24.7 % to 1.3 %. The hydrogen consumption after HDO process was 53.5 mol/kg bio-oil. In order to reduce the amount of hydrogen consumption, the single stage esterification/HDO was performed under supercritical ethanol atmosphere at similar hydrogen pressure (5.5 MPa). Our results suggested that the catalyst in supercritical media could facilitate the conversion of most acids into various kinds of esters in the upgrading process that consequently reduced the hydrogen consumption to 31.8 mol/kg bio-oil. The HHV and oxygen content of the liquid hydrocarbon product after esterification/HDO process were 27.1 MJ/kg and 1.6 % respectively. Moreover, less coke was formed in the case of esterification/HDO compared to HDO alone that increased the catalyst life. This study showed that the esterification and HDO of bio-oil could be carried out simultaneously in order to reduce the cost of upgrading process.<br/>

Upgrading of rice straw catalytic pyrolysis oil via single stage esterification/hydrodeoxygenation

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.