Biofuels & Bioenergy

Lignocellulosic biomass becomes very attractive as feedstock for the production of pyrolysis bio-oils, both scientifically and economically. Still, these products cannot be used as a liquid fuel or additive due to their excessive oxygen content, and poor chemical stability. Therefore, upgrading treatments are required. Catalytic hydrodeoxygenation is considered to be one of the most effective routes for bio-oil transformation. The present work involves the study and understanding the reaction pathway of the hydrodeoxygenation of guaiacol as a representative chemical of the bio-oil obtained from pyrolysis of lignocellulosic biomass, which contains 25.8% of oxygen due to the characteristic of methoxyphenol linkages. For this purpose catalysts based on Ni (5 wt.%) loaded on various supports (hierarchical ZSM-5, SBA-15, Al-SBA-15 and commercial H-ZSM-5). The samples were characterized in detail using N2 adsorption-desorption isotherms, Powder X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Temperature Programmed Reduction and Desorption (H2-TPR/NH3-TPD). Subsequently, all the prepared catalysts were tested in HDO of guaiacol (3.3 wt.% in decaline (50 ml) in a 100 ml stainless steel (SS) high pressure stirred batch reactor. The reaction was carried out under 40 bars of hydrogen partial pressure and the temperature was 260 ËšC, with the constant stirring speed (1000 rpm) for 2 hours. The liquid and gas products were analyzed by GC and GC-MS. These catalysts reveal different hydrogenation and hydrogenolysis routes based on supports. Ni/h-ZSM-5 exhibits a better deoxygenation activity with a percentage of HDO around 98 % at 260 ËšC, 2 hours. In addition, we correlated hydrophobic and hydrophilicity of the catalysts with HDO results.