Abstract:
The influence of ZrO2-Al2O3 composite oxides used as the support on the activity of NiMo catalyst was studied via hydrodeoxygenation (HDO) of guaiacol (GUA) and bio-oil. In this research, a series of ZrO2-Al2O3 composite supported with ZrO2/Al2O3 molar ratios of 0/1, 1/4, 2/3, 4/1 and 1/0 was synthesized by hydrothermal method. Then the NiMo/ZrO2-Al2O3 catalysts were prepared using the sequential impregnation method using 3.3 wt% Ni and 15.0 wt% Mo. The effect of HDO parameters: initial H2 pressure (10-30 bar) and reaction times (2-6 h) on catalytic activity were investigated. Before HDO process, the catalysts were in-situ reduced under 10 bar initial H2 pressure at 400 oC for 2h. The HDO was conducted at 300oC under the stirring rate of 400 rpm. The results showed that the NiMo/ZrO2-Al2O3 catalysts provided the lower GUA conversion and yield of phenol than NiMo/-Al2O3. However, this catalyst could inhibite the coke formation during the HDO of GUA. For the effect of initial H2 pressure, it was found that the use of ZrO2-Al2O3 support with a molar ratio of 2/3 for NiMo catalyst showed the increasing GUA conversion and yield of phenol with increasing the initial H2 pressure from 10 to 30 bar. In addition, the NiMo/ZrO2-Al2O3 2/3 could inhibite the coke when the initial H2 pressure was higher. To consider the effect of reaction time, the increase in the reaction time induced the higher GUA conversion, yield of phenol and coke formation on surface of catalysts.For the study of HDO of real bio-oil derived from pyrolysis sawdust powder, it was observed that the use of NiMo/ZrO2-Al2O3 2/3 could reduce oxygen content of bio-oil from 55.9 to 35.3 wt% resulting the higher heating value from 13.5 to 22.8 MJ/kg.