DEVELOPMENT OF MICROWAVE PYROLYSIS BIOCHAR AS CARBON CATALYSTS FOR HIGH VALUE CHEMICALS AND HYDROCARBONS

Lei Zhu

Catalytic pyrolysis of lignocellulosic biomass is considered as a promising thermochemical process for the production of fuels and chemicals, which are currently obtained from petrochemical infrastructure. With the development of biomass pyrolysis, increasing amount of biochar will be produced for applications. Most of the biochar exploitation mainly highlighted in the area of water treatment and soil amendment. However, the potential value of the pyrolysis biochar used as carbon based catalyst is still in its infancy. This PhD dissertation aims to investigate the technical and economic feasibility of a low cost biochar catalyst for microwave-assisted catalytic biomass pyrolysis, and to obtain upgrading bio-oil with increased hydrocarbon yields and low oxygen content. Furthermore, upgrade it into alternative transportation fuels and commodity chemicals. The results indicated that the surface functional groups of biochar were significantly influenced by the pyrolysis temperature and residence time. An adequate prediction model was developed to describe the development of carbon surface functional groups. The in situ catalytic pyrolysis of Douglas fir pellets with biochar catalysts was performed in a microwave reactor. The highest amount of hydrocarbons yield (up to 52.77% selectivity of bio-oil) was achieved from catalytic pyrolysis over biochar catalyst. A non-condensable gas enriched in H2, CO, and CO2 was observed, and analyzed by micro-GC. The amounts of H2 and CO increased during catalytic pyrolysis compared to the non-catalytic runs. GC/MS analysis results showed that the quantity of lignin derived guaiacols decreased dramatically with the increase of the ratio of catalyst to biomass. The biochar catalyst exhibited good selectivity towards hydrocarbon and phenol compounds, simplifying the chemical composition, reducing undesirable compounds and producing pyrolysis oil at an acceptable yield. Based on these outcomes, structural characteristics, thermal behavior and reaction kinetics regarding non-catalytic pyrolysis and catalytic pyrolysis over biochar catalysts were also studied. In addition, the techno-economic analysis of the integrated microwave assisted catalytic pyrolysis processes from lignocellulosic biomass to renewable hydrocarbon and commodity chemicals was evaluated in the dissertation as well. Modification and characterization of biochar could be a new way to improve or extend their catalytic application in biomass conversion and bio-oil upgrading.

DEVELOPMENT OF MICROWAVE PYROLYSIS BIOCHAR AS CARBON CATALYSTS FOR HIGH VALUE CHEMICALS AND HYDROCARBONS

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