Enhancement of bio-oil hydrodeoxygenation activity over Ni-based bimetallic catalysts supported on SBA-15

Abstract

Three Ni-based bimetallic catalysts were prepared on hexagonally structured mesoporous SBA-15 supports(NiCu/SBA-15, NiMn/SBA-15, NiZn/SBA-15). Hydrodeoxygenation (HDO) of biooil was performed at 250–350 °C for 45 min with 3 MPa H2 pressure in the presence of the three catalysts. HDO reaction yielded a primary products of gas, two immiscible liquids (light oil and heavy oil) and char. High catalyst surface area resulted in a high heavy oil yield (40.8–60.6 wt%). Bimetallic catalysts decreased yield of light oil (3.6–11.7 wt%), while increased the gas fraction (16.3–43.7 wt%) compared with the data from the monometallic Ni/SBA-15 catalyst (20.3–30.4 and 6.6–26.2 wt% yields, respectively). Use of bimetallic catalysts instead of monometallic catalyst enhanced fuel properties of heavy oil; such as moisture content (from 11.4 to 2.0–8.8 wt%), acidity (from 62.2 to 49.2–59.8 mg KOH/g oil), viscosity (from 7.1 to 3.2–4.3 cSt) and oxygen content (from 32.2 to 26.2–34.6 wt%). Cyclohexanone, 4-ethylphenol, and methyl-cyclopentenone, which were lack in the bio-oil, were detected after HDO reaction and these components could be produced via demethoxylation, hydrogenation, dehydration, and dehydroxylation under the presence of bimetallic catalysts, thereby improving the fuel properties of the heavy oil.