Hydrothermal Liquefaction (HTL) of Lignocellulosic Biomass for Biocrude Production: Reaction Kinetics and Corrosion-Resistance Performance of Candidate Alloys for Reactors
Abstract
In recent years, the rapid increase in the demand for clean energy and green chemicals as well as concerns over the supply and environmental impacts associated with fossil. resources have stimulated intensive research on conversion of bioresources, such as lignocellulosic biomass and biowaste, into energy, fuels, chemicals, and materials.
Hydrothermal liquefaction (HTL) is a unique thermochemical conversion process, particularly applicable for the conversion of wet biomass and biowaste feedstocks. Most of the biomass HTL studies are conducted in batch reactor and focus on the effects of catalysts, reaction temperature and time on production efficiency and chemical properties of the products. Besides, HTL process is operating usually in a reaction medium in the presence of hot-compressed water (under elevated temperature and high pressure) and usually an alkali catalyst. It is thus necessary to assess corrosion-resistance performance of various candidate alloys for reactors.
In this thesis work, a kinetic model based on chemical compositions (cellulose, hemicellulose, and lignin) was developed for predicting HTL product yields. Validation with our experimental results and the publicly available HTL data in literature obtained with lignocellulosic biomass feedstocks was performed to assess the quality/reliability of the model predictions. In addition, the influence of reaction atmosphere (N2, H2, and O2) on HTL process was investigated in this thesis work. Bio-oils obtained under N2 or H2 exhibited higher energy recovery and better quality. Moreover, the comparison between the performance of batch and continuous-flow reactors in HTL of several lignocellulosic biomass and lignin-rich biomass (lignin and black liquor) was investigated. The continuous-flow operations resulted in slightly poorer qualities compared with those obtained from batch operations due to the relatively short reaction time. Furthermore, this thesis examined the corrosion modes and extents of SS316L for reactor construction under static and batch-mode catalytic HTL conversion of two typical biomass feedstocks, Bamboo and Black liquor. These results would be helpful for designing the HTL systems for continuous production and the development and deployment of HTL technology in Canada and the global bioenergy industry.