Catalytic hydrothermal liquefaction of rice straw for production of monomers phenol over metal supported mesoporous catalyst

[Display omitted] •Hydrothermal liquefaction of rice straw was investigated.•Maximum bio-oil yield (56.2 wt%) was obtained with Ni/SBA-15 under ethanol solvent.•Higher % of phenolic monomer compounds were obtained.•Catalytic bio-oil showed the higher heating value (HHV) 36.6 MJ/kg. The catalytic (SBA-15, Ni/SBA-15, Al/SBA-15 and Ni-Al/SBA-15) hydrothermal liquefaction (HTL) of rice straw biomass was examined at different temperature with different amount of catalyst in the presence of different solvents. In comparison with water solvent liquefaction, the bio-oil yield significantly increased under alcoholic solvent (ethanol and methanol). The highest bio-oil yield was observed for water (44.3 wt%) with Ni-Al/SBA-15, while for ethanol (56.2 wt%), and for methanol (48.1 wt%) with, Ni/SBA-15 catalyst. The loading of Ni and Al on SBA-15, the acid strength of the catalyst enhanced. Bio-oils yield were analyzed with the help of GC–MS, FT-IR, NMR, GPC and CHNS. From the GC–MS analysis, the main monomeric phenolic compounds were produced, phenol, 4-ethyl-phenol, 2-methoxy-phenol, 2-methoxy-4-ethyl-phenol and Vanillin. It was observed by CHNS and GPC analysis of the bio-oil, compared to the non-catalytic liquefaction reaction, the catalytic liquefaction reaction promotes the hydrogenation/hydrodeoxygenation and produced lower molecular weight bio-oils.