Hydrodeoxygenation of pinyon-juniper catalytic pyrolysis oil using red mud-supported nickel catalysts

Red mud (RM) is an alkaline waste generated in the Bayer process of alumina production. In the present study red mud supported nickel catalysts (Ni/RM) were prepared at different concentrations of nickel (10, 20, 30, 40, 50, and 65 wt.%) and used to hydrodeoxygenate (HDO) pinyon juniper (PJ) catalytic pyrolysis oil. Increasing the nickel content improved the activity of Ni/RM catalysts for HDO reactions. Maximum organic liquid yield (68.6%) was obtained when 40%Ni/RM was used. The upgraded oil had oxygen content of 1.35 wt.% and higher heating value of 45.77 MJ/kg compared to 24.88 wt.% and 28.41 MJ/kg, respectively, for the crude oil. For comparison, commercial Ni/SiO2-Al2O3 was also evaluated in HDO experiments. The HDO oil properties obtained using 40%Ni/RM at reaction temperature of 400 degrees C was similar to that of commercial Ni/SiO2-Al2O3 at reaction temperature of 450 C. However, the organic liquid yield was much higher for 40%Ni/RM (68.6%) compared to the commercial Ni/SiO2-Al2O3 (41.8%). The commercial Ni/SiO2-Al2O3 produced more gas (27.6%) than the 40%Ni/RM (16.4%) and the coke yields for the commercial catalyst and Ni/RM catalyst were 7.3% and 4.2% respectively. Overall, application of Ni/RM improved HDO reactions and reduced cracking and coke formation compared to commercial Ni/SiO2-Al2O3.