Date of Defense
16-6-2025 12:00 PM
Location
F1, 2007
Document Type
Thesis Defense
Degree Name
Master of Science in Chemical Engineering (MSChE)
College
College of Engineering
Department
Chemical and Petroleum Engineering
First Advisor
Dr. Joy Tannous
Keywords
Hydrodeoxygenation, Biomass, Biofuel, Vanillin, Guaiacol
Abstract
With the exponential increase in the human population and energy demand coupled with the alarming levels of worldwide CO2 emissions and the global warming crisis, there is a shift of focus towards developing and deploying clean and renewable energy sources. Biomass is a widely available renewable energy source that offers a promising sustainable alternative to fossil fuels, especially in the case of liquid biofuels production. However, unlike fossil fuels, biomass inherently contains high oxygen content which must be reduced in the biomass-to-biofuel upgrading process in order for the biofuel to provide comparable amounts of energy per unit volume to traditional fuels currently used as well as matching their physicochemical properties. Therefore, hydrodeoxygenation (HDO) is an essential step lying at the heart of the upgrading process. This research project aims at upgrading biomass model compounds, namely vanillin and guaiacol, into partially deoxygenated biofuel precursor through the hydrodeoxygenation reaction. The deoxygenation pathway investigated starts with carrying out a hydrodeoxygenation reaction on vanillin to produce guaiacol, followed by another hydrodeoxygenation reaction on guaiacol to produce phenol. Novel catalysts are prepared and tested at different metal loadings, and the performance of the catalysts is evaluated based on the conversion, selectivity, yield and the degree of deactivation. In this work, the synthesized catalysts use nickel (Ni), cobalt (Co) and iron (Fe) and the noble metal rhodium (Rh) supported each on the HZSM-5 zeolite. Various characterization techniques were used, including Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), X-ray Diffraction (XRD), Temperature Programmed Reduction (TPR) and Scanning Electron Microscope (SEM), to elucidate the catalysts’ structures and to comprehend the origins of the observed catalytic activity in the hydrodeoxygenation. Seven hydrodeoxygenation reactions were carried out on vanillin with H2 flow rate of 100mL/min at 300℃ and atmospheric pressure. Ni/HZSM-5 catalyst showed the best performance among the transition metals with the peak performance being at the 10% loading with a conversion of 65.64% and a 96.35% selectivity towards guaiacol. Loading the same catalyst with 0.5% of the noble metal rhodium (i.e. 0.5%Rh-10%Ni/HZSM-5) boosted the conversion to 72.86% while maintaining almost the same selectivity towards guaiacol. Several products were obtained from the guaiacol hydrodeoxygenation at the same conditions over 10%Ni/HZSM-5 including phenol, m-cresol and o-cresol, with phenol dominating at 57.5% selectivity. The ultimate goal of the project is to optimize the hydrodeoxygenation reaction for biomass upgrading through developing novel and efficient catalysts as well as exploring a new practical reaction pathway. Achieving this goal will make biofuels more obtainable and generate greater interest in this type of renewable energy sources, which will eventually reduce the environmental damages caused by the conventional fuels that have been powering transportation for decades.
Included in
CATALYTIC HYDRODEOXYGENATION OF BIOMASS MODEL COMPOUNDS USING NI, CO AND FE OVER HZSM-5
F1, 2007
With the exponential increase in the human population and energy demand coupled with the alarming levels of worldwide CO2 emissions and the global warming crisis, there is a shift of focus towards developing and deploying clean and renewable energy sources. Biomass is a widely available renewable energy source that offers a promising sustainable alternative to fossil fuels, especially in the case of liquid biofuels production. However, unlike fossil fuels, biomass inherently contains high oxygen content which must be reduced in the biomass-to-biofuel upgrading process in order for the biofuel to provide comparable amounts of energy per unit volume to traditional fuels currently used as well as matching their physicochemical properties. Therefore, hydrodeoxygenation (HDO) is an essential step lying at the heart of the upgrading process. This research project aims at upgrading biomass model compounds, namely vanillin and guaiacol, into partially deoxygenated biofuel precursor through the hydrodeoxygenation reaction. The deoxygenation pathway investigated starts with carrying out a hydrodeoxygenation reaction on vanillin to produce guaiacol, followed by another hydrodeoxygenation reaction on guaiacol to produce phenol. Novel catalysts are prepared and tested at different metal loadings, and the performance of the catalysts is evaluated based on the conversion, selectivity, yield and the degree of deactivation. In this work, the synthesized catalysts use nickel (Ni), cobalt (Co) and iron (Fe) and the noble metal rhodium (Rh) supported each on the HZSM-5 zeolite. Various characterization techniques were used, including Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), X-ray Diffraction (XRD), Temperature Programmed Reduction (TPR) and Scanning Electron Microscope (SEM), to elucidate the catalysts’ structures and to comprehend the origins of the observed catalytic activity in the hydrodeoxygenation. Seven hydrodeoxygenation reactions were carried out on vanillin with H2 flow rate of 100mL/min at 300℃ and atmospheric pressure. Ni/HZSM-5 catalyst showed the best performance among the transition metals with the peak performance being at the 10% loading with a conversion of 65.64% and a 96.35% selectivity towards guaiacol. Loading the same catalyst with 0.5% of the noble metal rhodium (i.e. 0.5%Rh-10%Ni/HZSM-5) boosted the conversion to 72.86% while maintaining almost the same selectivity towards guaiacol. Several products were obtained from the guaiacol hydrodeoxygenation at the same conditions over 10%Ni/HZSM-5 including phenol, m-cresol and o-cresol, with phenol dominating at 57.5% selectivity. The ultimate goal of the project is to optimize the hydrodeoxygenation reaction for biomass upgrading through developing novel and efficient catalysts as well as exploring a new practical reaction pathway. Achieving this goal will make biofuels more obtainable and generate greater interest in this type of renewable energy sources, which will eventually reduce the environmental damages caused by the conventional fuels that have been powering transportation for decades.