(126d) Catalytic Hydrothermal Liquefaction of Pinewood, Switchgrass and Wastepaper for H2, Biocrude and Bio-Oil Production

The authors report (a) catalytic hydrothermal liquefaction (HTL) of different biomass substrates (pinewood, switchgrass and wastepaper) at 200-275 ^oC in presence of a homogeneous nitrate salt catalysts: Ni(NO₃)₂, Ca(NO₃)₂, Co(NO₃)₂ and Fe(NO₃)₃ for the production of H₂, biocrude and bio-oil, (b) detailed investigation of biocrude and bio-oil generated from a biomass and (c) study of the possible reaction pathways for production of bio-oil with their energy content. To generate H₂ and biocrude, a slurry of biomass was prepared with different biomass to solvent (B:S) ratios of 1:10, 1:30, and 1:75 and loaded in the SS316 PARR reactor and heated to different temperatures. While the reaction was in progress, gas samples were withdrawn at regular time intervals and analyzed using GC equipped with thermal conductivity detector and Chrompack GC column. The product gas analysis revealed the presence of mainly H₂, CH₄, CO and CO₂. The processed slurry was centrifuged to recover biocrude and residue. The biocrude was further analyzed by TOC analyzer and HPLC. Among different catalysts used, Ni(NO₃)₂ yielded highest mol% H₂ at 275 ^oC and a maximum biocrude at 250 ^oC. The biocrude was found to contain sugars, C₁-C₃ carboxylic acids such as lactic, propionic, acetic and formic, HMF/furfural and other oxygenated compounds, which were analyzed by HPLC and GC–MS. The biocrude obtained was further processed to recover light bio-oil (LBO), heavy bio-oil (HBO) and residue which were found to have higher heating value (HHV)’s compared with original biomass. The results obtained on H_2,  biocrude/bio-oil composition obtained during HTL of biomass substrates and possible reaction pathways will be presented in detail.