(688e) Renewable Fuel Production Via Methanol-Assisted Biomass Liquefaction Process

Renewable Fuel Production via Methanol-Assisted Biomass Liquefaction Process

Jiajia Meng¹, Kevin McCabe¹, Kelly Mastro¹, Eric Larson² and Santosh Gangwal¹

1.      Southern Research, 5201 International Dr, Durham, NC 27712

2.      Princeton Environmental Institute, Princeton University, NJ 08544

ameng@southernresearch.org; (919) 282-1050

Biomass hydrothermal liquefaction (HTL) using compressed hot water requires severe reaction temperature (~350 °C) and pressure (~3000 psi) to deconstruct biomass constituents; it is therefore energy intensive, capital intensive and difficult to scale up.  To advance the technology, this project aims to develop a low-severity methanol assisted hydrothermal liquefaction process to convert woody biomass into stabilized bio-oils. The bio-oil is targeted to be co-processed with petroleum streams using existing refinery infrastructure for the production of drop-in transportation fuel, leveraging existing refinery capital for bio-fuel production. The liquefaction conditions were optimized using a Parr reactor according to statistically designed experiments to achieve high biomass conversion, high bio-oil yield and relatively low oxygen content in the bio-oil. Under optimized conditions, the process achieved ~90% biomass conversion and ~50% bio-oil yield. Based on these experiments, a preliminary commercial embodiment of the liquefaction process was developed. The bio-oils were found to contain ~22% oxygen with low moisture (~1 wt.%) and acid content (total acid number 1-5 mg KOH/g dry oil).  The molecular weight of the bio-oil did not vary significantly over a six-month room-temperature storage indicating their stable nature. Furthermore, at anticipated commercial conditions, the bio-oil produced were easily flowing liquid at 40^oC.  For refinery insertion purposes, these bio-oils were hydro-deoxygenated using a proprietary catalyst in a continuous ½’’ trickle-bed reactor for oxygen removal. The upgrading experiments showed that the bio-oil oxygen content could be reduced from 22 wt % to 1.5 wt % with low hydrogen consumption (<0.03 g/g dry bio-oil) under mild conditions.  Characterization of the upgraded oil showed that it was essentially free of water and acid, and contained diesel-range hydrocarbons based on simulated distillation results.  Also, the upgraded oil was miscible with a petroleum-based diesel, therefore enabling co-processing in the refinery. These results were applied to develop mass and energy balances of a commercial process for economic production of biofuel from biomass. A techno-economic evaluation and lifecycle assessment of the process was carried out.