Hydrotreatment of bio-oil over Ni-based catalyst

Inexpensive non-sulfided Ni-based catalysts were evaluated for hydrotreatments using phenol as model compound. HZSM-5, a zeolite with different ratio of Si/Al and γ-Al2O3 were impregnated with Ni(NO3)2·6H2O and calcined at 450 °C. Conversion rates and product distribution for treatment of phenol at 160–240 °C in the presence of catalysts with nickel loads of 6, 10, 14 and 17 wt.% were determined. Phenol conversion was highest (91.8%) at 240 °C in the presence of HZSM-5(Si/Al = 38) loaded with 10% Ni. When hydrotreatment was carried out with bio-oil obtained from pyrolysis of pine sawdust under the optimal conditions determined for phenol, the pH of bio-oil increased from 2.27 to 4.07, and the hydrogen content increased from 6.28 to 7.01 wt.%. The decrease in acidity is desirable for the use of upgraded bio-oil.

► Ni/HZSM-5 catalyst possesses the catalytic activity for cracking and hydrogenation.
► Cracking reaction and hydrogenation reaction take place simultaneity during the hydrotreating process.
► Reaction temperature has great effect on product selectivity for benzene and cyclohexane.
► The pH value of bio-oil increased from 2.27 to 4.07 after upgrading.