| The production of renewable and carbon-neutral bio-oil from biomass has been proposed as a way of reducing our dependency on petroleum as well as reducing greenhouse gas emissions. Currently, the production technologies include bio-ethanol, bio-diesel, pyrolysis bio-oil and gasification-Fischer Tropsch. However, the production of bioethanol and bio-diesel from edible sources has an adverse effect on food supplies and prices, thus not desirable. Pyrolysis and gasification-Fischer Tropsch can use inedible biomass as a feedstock, but require the biomass to be dried prior to conversion.;The results of this investigation showed that, at 300 °C, the highest bio-oil yield of 49.8 mass % was obtained from HTC of cattle manure, and that the heating value of the biooil was 35.5 MJ/kg, higher than 29.8 MJ/kg of bio-ethanol and 19.0 MJ/kg of pyrolysis bio-oil. The main non-polar components of the bio-oil were toluene, ethyl benzene and xylene, which are aromatic components of fossil crude oil. The reaction pathways of HTC were greatly influenced by acidic, neutral and alkaline conditions. Taking cellulose as an example, under acidic and alkaline conditions, the main component of its HTC biooils was 5-(Hydroxymethyl)furfural and carboxylic acids, respectively. Under neutral conditions, both 5-(Hydroxymethyl)furfural and carboxylic acids were formed, due to the self-disassociation of water to H+ and OH- . Moreover, by controlling the reaction pathways and using metal catalysts, HTC further improved, and converted glucose and cellulose to alkane bio-oils with similar chemical compositions as liquefied petroleum gas and gasoline, respectively. Via catalytic HTC, therefore, a quick production of fossil petroleum from renewable wet biomass resources could become feasible.;In this thesis research, hydrothermal conversion (HTC) of waste biomass to bio-oil was studied, which can directly convert inedible biomass to bio-oil without predrying. The three specific aims of thesis research were as follows. (1) From an engineering point of view, HTC of waste biomass (cattle manure) to bio-oil was investigated and evaluated in terms of yield and quality. (2) In order to help understand HTC, the reaction mechanism of HTC was studied with a focus on the changes of HTC reaction pathways with the pH levels of reaction media. (3) Based on the results above, HTC was further improved to produce high-quality bio-oil (alkanes). |
