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Wet algae slurries can be converted into an upgradeable biocrude by hydrothermal liquefaction (HTL). High levels of carbon conversion to gravity separable biocrude product were accomplished at relatively low temperature (350°C) in a continuous-flow, pressurized (sub-critical liquid water) environment (20 MPa). As opposed to earlier work in batch reactors reported by others, direct oil recovery was achieved without the use of a solvent and biomass trace components were removed by processing steps so that they did not cause process difficulties. High conversions were obtained even with high slurry concentrations of up to 35 wt.% of dry solids. Catalytic hydrotreating was effectively applied for hydrodeoxygenation, hydrodenitrogenation, and hydrodesulfurization of the biocrude to form liquid hydrocarbon fuel. Catalytic hydrothermal gasification was effectively applied for HTL byproduct water cleanup and fuel gas production from water soluble organics, allowing the water to be considered for recycle of nutrients to the algae growth ponds. As a result, high conversion of algae to liquid hydrocarbon and gas products was found with low levels of organic contamination in the byproduct water. All three process steps were accomplished in bench-scale, continuous-flow reactor systems such that design data for process scale-up was generated.

Catalytic hydroprocessing has been applied to biomass fast pyrolysis liquid product (bio-oil) in a bench-scale continuous-flow fixed-bed reactor system. The intent of the research was to develop process technology to convert the bio-oil into a petroleum refinery feedstock to supplement fossil energy resources and to displace imported feedstock. The project was a cooperative research and development agreement among UOP LLC, the National Renewable Energy Laboratory and the Pacific Northwest National Laboratory (PNNL). This article is focused on the process experimentation and product analysis undertaken at PNNL.This article describes the experimental methods used and relates the results of the product analyses. A range of catalyst formulations were tested over a range of operating parameters including temperature, pressure, and flow rate with bio-oil derived from several different biomass feedstocks. Effects of liquid hourly space velocity and catalyst bed temperature were assessed. Details of the process results were presented included product yields and hydrogen consumption. Detailed analysis of the products were provided including elemental composition, chemical functional type determined by mass spectrometry, and product descriptors such as density, viscosity, and total acid number. In conclusion, this article provides an understanding of the efficacy of hydroprocessing as applied to bio-oil.

Catalytic hydroprocessing has been applied to the fast pyrolysis liquid product (bio-oil) from softwood biomass in a bench-scale continuous-flow fixed-bed reactor system. The intent of the research was to develop process technology to convert the bio-oil into a petroleum refinery feedstock to supplement fossil energy resources and to displace imported feedstock. This paper is focused on the process experimentation and product analysis. A range of operating parameters, including temperature from 170 or 250 to 400 °C in the two-stage reactor and flow rate of 0.19 liquid hourly space velocity, was tested with bio-oil derived from pine wood. Times on stream of up to 90 h were evaluated, and losses of catalyst activity were assessed. Product yields of 0.35–0.45 g of oil product/g of dry bio-oil feed with hydrogen consumptions from 342 to 669 L/L of bio-oil feed were measured. Analyses determined that product oils with densities of 0.82–0.92 g/mL had oxygen contents of 0.2–2.7 wt % and total acid number (TAN) of <0.01–2.7 mg of KOH/g. In summation, the paper provides an initial understanding of the efficacy of hydroprocessing as applied to the Finnish pine bio-oil.

Improved catalyst formulations have been developed and tested for hydrothermal gasification of wet organics. A high-pressure (about 20 MPa) and high-temperature (about 350 °C) liquid water processing environment was used to treat organic chemical model compounds. The organic feedstocks were converted primarily to methane and carbon dioxide in the presence of a heterogeneous catalyst. Test results with different catalyst formulations showed that catalyst composition could be tailored for the hydrothermal environment to effectively process wet wastes and wastewater and to recover useful fuel gas.