The content of oxygen in fossil oil ranged from 0.05% to 1.5%. As respect to nitrogen, the concentration distributed between 0.01% and 0.7% [20]. Compared to fossil oil, the oxygen and nitrogen contents in bio-oil were still too high to use this product oil as a gasoline or diesel fuel substitute. NOx pollutants would form after the burning of bio-oil products, which was undesirable for environmental and legislative reasons. Thus, denitrogenation and additional deoxygenation are needed for an improved bio-fuel.