Rapid industrialization and economic development have pushed up energy demands, especially in the transportation sector. Environmental concern and limited availability have shifted our focus from fossil fuels to renewable biomass fuels. Pyrolysis recovered bio-oil contains many oxygenated organic compounds that impart several undesirable properties such as low heating value, instability, and high viscosity to bio-oil, making it inappropriate to be used as transportation fuel. Thus there is a need to upgrade its properties by reducing its oxygen content. Hydrodeoxygenation (HDO) is the most effective method which converts oxygenated compounds into hydrocarbons under high hydrogen pressure in the presence of catalyst. Among all catalysts, transition metals are the most suitable catalysts having high activity and low cost. Co is one of the main components of CoMo/Al2O3 catalyst used in hydrodesulfurization. This study aimed to investigate the effects of bimetallic catalyst FeCo/Al2O3 for bio-oil HDO. FeCo/Al2O3 catalysts were prepared by wet impregnation of cobalt nitrate hexahydrate and/or iron nitrate nonahydrate aqueous solution (with 10 wt.% metal loading) on commercial Al2O3 support. The Fe:Co ratio in the FeCo/Al2O3 catalyst was 1:1. Physiochemical properties of raw and upgraded bio-oil are shown in Table 1. Density of bio-oil reduces after upgradation due to conversion of high molecular weight compounds into lighter ones. The reduction in oxygen content was attributed to hydrodeoxygenation, decarbonylation and decarboxylation reactions. Metallic Fe selectively facilitates hydrocarbon formation through hydrodeoxygenation, without promoting the hydrogenation of aromatic rings. However metallic Co catalyzes both hydrogenation and hydrogenolysis of organic compounds during bio-oil upgradation. Metallic Co also increases the direct cleavage of C-O bonds; thus, more oxygenates were removed in Co/Al2O3 catalyst presence compared to Fe/Al2O3 and FeCo/Al2O3 catalysts. Bio-oil oxygen content was reduced with the increase in carbon content for all the catalysts. The FeCo/Al2O3 catalyst resulted in the highest reduction in viscosity of upgraded oil as 1.82 cst. Results showed that upgraded oil has improved its properties, making it appropriate for energy production.

Upgradation of pyrolysis bio-oil through hydrodeoxygenation using bimetallic FeCo/Al2O3 catalyst

ACS Spring Meeting 2021

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