Partial Upgrading of Lignocellulosic Bio-Oil via Deep Catalytic Hydrotreating
Date
2021-09-23
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Abstract
According to the International Energy Agency, bioenergy accounts for one-tenth of the world's total primary energy supply and biofuel production is forecasted to increase 25% by 2024. The bio-oil is composed of a complex mixture of oxygenated compounds with a relatively high concentration of water. Compared to crude oil, bio-oil has high oxygen content, lower energy density, high acidity, high viscosity and water content. Submitting the bio-oil to atmospheric distillation at the refinery is not possible at this stage since the highly reactive compounds in the bio-oil will plug the distillation column at high temperatures, and moreover, high temperatures will accelerate the corrosion effect of the bio-oil in the refinery lines. Therefore, an upgrading step is necessary to make the bio-oil admissible to the refinery. The ultimate goal of this research is to produce biofuel equivalent to conventional fuels from lignocellulose-derived bio-oil. The main objective of this study is to reduce the oxygen content of the bio-oil via the catalytic hydrotreating process and to improve the quality of the upgraded oil. The effect of the process variables such as operating pressure, temperature and space velocity on the product quality was studied. The best results were obtained using CAT-M5, at 1750 psig, 370 C and 0.4 h-1 space velocity resulting in 77% reduction in oxygen content, 99.5% reduction in viscosity, 100% reduction in total acid number, 55% phenol conversion and 91% residue conversion. It was found that increasing pressure, unlike temperature, does not have a noticeable effect on microcarbon residue reduction, viscosity, and boiling point distribution of the product, but it improves the degree of deoxygenation and molar H/C ratio. Moreover, at temperatures higher than 350 C, hydrocracking along with hydrogenation notably improved the residue conversion, viscosity and MCR reduction. Comparing the performance of catalysts showed that CAT-M5, unlike CAT-M3, eliminated the solid precipitation in the products thanks to its large pore size. Furthermore, CAT-M5 had a higher residue conversion rate, MCR and viscosity reduction rate. In contrast, CAT-M3 had a better performance in deoxygenation and phenol conversion.
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Keywords
Bio-Oil, Deep Hydrotreating, Catalytic Upgrading, Hydrodeoxygenation
Citation
Marashi Shoushtari, N. S. (2021). Partial Upgrading of Lignocellulosic Bio-Oil via Deep Catalytic Hydrotreating (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.