HTU diesel

Conversion of biomass at a temperature of 300 350 °C and a pressure of 120-180 bar within the so-called HydroThermal Upgrading (HTU) process yields a mixture of hydrocarbons, carbon dioxide, water and dissolved organics, which can be further processed in a catalytic HydroDeOxygenation (HDO) step to yield diesel with characteristics similar to fossil diesel. A major advantage is that wet biomass feedstocks can be employed without drying in contrast, water at hydrothermal conditions acts as a solvent and reactant at the same time, leading to a product with less oxygen compared to biocrude prepared by pyrolysis. 

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Fig. 5.2 The main crop-to-energy chains. BtL Biomass-to-Liquid, GtL Gas-to-Liquid, ETBE Ethyl tert-butyl ether, MTBE Methyl tert-butyl ether, MeOH Methanol, DME Dimethyl ether. Pyrolysis oil, HTU-Diesel (Hydro Thermal Upgrading), ethanol and hydrogen from ligno-cellulosic species are not considered here because of their minor practical relevance in the near future...

HTU [Hydro-Thermal Upgrading] A process for making liquid fuels from biomass. The biomass is made into an aqueous slurry and heated to 300°C under 200 bar. The resulting crude oil is catalytically hydrogenated to give a high-quality naphtha or diesel fuel. Developed by Royal Dutch Shell from 1982 to 1993, but not commercialized. 

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