Catalysis and Reaction Engineering Commons^™

Conversion Of Biomass Derived Tar In A Catalytic Post-Gasification Process, Floria Rojas Chaves

Electronic Thesis and Dissertation Repository

The present MESc thesis reports the performance of a fluidizable CeO₂ promoted Ni/γ-Al₂O₃ catalyst to be used in a post-gasification process for tar removal. The catalysts developed were prepared using the incipient wetness technique and characterized chemically and physically, using the following techniques: N₂ Adsorption-Desorption, XRD, NH₃ and CO₂ TPD, Pyridine-FTIR, H₂-TPR, and H₂-Pulse Chemisorption. The catalysts were tested in a fluidized CREC Riser Simulator, in the 500°C-550°C temperature range, within 5 s-10 s reaction times, using both steam and steam-H₂/CO₂ atmospheres.A 2-methoxy-4-methlyphenol (2M4MP) compound was …

Development Of Photocatalytic Reactor System For Dye Degradation From Lab To Pilot Scale, Waleed Jadaa

Electronic Thesis and Dissertation Repository

The overall goal of the research is to develop a novel photocatalytic reactor system, namely, a bubble column photoreactor for the degradation of resistant pollutants, with a particular emphasis on azo dyes. To achieve the objective, different sub-objectives were performed employing lab and pilot-scale reactors with the application of simulated wastewater. Direct Blue (DB15) was used as a model compound for the azo dyes class for this study. Firstly, the influence of various variables such as pH, dye concentration, and catalyst loading to determine optimal combinations of DB15 removal. The experiments were conducted in a swirl flow photoreactor under the …

Co2 Derived Carbon Capture Using Microalgae In A Photobiocrec Unit, Maureen D. Cordoba Perez

Electronic Thesis and Dissertation Repository

Microalgae has the potential to contribute to carbon dioxide capture, resulting in the production of alternative fuels and valuable chemical products. To accomplish this, high-efficiency photobioreactors must be conceptualized, designed, and established, in order to achieve high inorganic carbon conversion, superior light utilization, and unique fluid dynamics.

In this PhD Dissertation, experiments with Chlorella vulgaris were carried out, in a 0.175L especially designed PhotoBioCREC unit, under controlled radiation and high mixing conditions. This unique design involves 1 mm-2 mm alumina particles, which keep photoreactor walls always clean, without compromising photon transmittance. Sodium bicarbonate (NaHCO₃) was supplied as the …

Experimental Study And Characterization Of Bubble Behaviors In The Orifice-Induced Hydrodynamic Cavitation, Haoxuan Zheng

Electronic Thesis and Dissertation Repository

Experimental studies were performed to characterize the development process of orifice-induced cavitation and transitional bubble behaviors. The transition from non-cavitation to fully developed cavitation was carefully studied. Cavitation bubble clouds were observed at orifice, indicating the inception of cavitation. The number of bubbles produced were dramatically increased while the averaged sizes of bubble reduced when cavitation was initiated. Both orifice opening ratio and perimeter can affect the cavitation developing process. A long orifice perimeter promotes the production of fine bubbles. The orifice plates with the smallest opening ratio generated a desired gas-liquid interfacial area at the lowest required pressure. An …

Hydrogen Production Via Photocatalytic Water Splitting Under Near-Uv And Visible Light Using Doped Pd Tio2, Bianca Rusinque

Electronic Thesis and Dissertation Repository

The present PhD thesis reports the modification of titanium dioxide (TiO₂) with palladium (Pd), to enhance hydrogen production via water splitting, using 2.0v/v% ethanol as a scavenger. Titanium dioxide was used as photocatalyst, given its ability to absorb photons, producing e^-/h⁺ pairs. Mesoporous TiO₂ was synthesized using a soft template, following the sol-gel method, to modify its morphological properties. Palladium was used as co-catalyst doping TiO₂ agent, narrowing the band gaps down to 2.51 eV, and creating additional active metal sites.

Water splitting experiments under near-UV and visible light irradiation were carried out …

Rational Design Of Highly Efficient Electrocatalysts Using Atomic Layer Deposition: From Nanoparticle To Single Atom, Junjie Li

Electronic Thesis and Dissertation Repository

Polymer electrolyte membrane fuel cells (PEMFCs) have been attracted significant attention due to their high energy efficiency. The electrocatalyst is one of the most important parts. However, state-of-the-art electrocatalysts suffer from several challenges, including 1) low stability under harsh working conditions; 2) low atomic utilization efficiency, especially for noble metals. This thesis, therefore, focuses on the design of highly efficient and stable electrocatalysts from nanoparticles down to single atoms using atomic layer deposition (ALD) and further understand the insight mechanisms.

Firstly, Pt nanoparticles are selectively deposited on the TiO₂ modified N-doped carbon nanotubes. The strong metal-support interactions between Pt …

Cluster Acceleration And Stabilization In Downflow Catalytic Reactors: Experimental And Cpfd Simulation Studies, Cesar Alejandro Medina Pedraza

Electronic Thesis and Dissertation Repository

Particle cluster dynamics in downflow reactors are of great importance for the implementation of large scale, environmentally friendly catalytic processes. Studies should address particle cluster velocities, solids holdups, and individual cluster sizes to establish reliable models for the unit scale up.

In this PhD dissertation, the individual characteristics of particle clusters, such as cluster size, velocity, and particle volume fraction, were measured in the feeding, intermediate, and fully developed flow sections of a cold-flow model unit using CREC-GS-Optiprobes. The downer unit employed in this research had a 0.051 m ID and a 2 m high acrylic column. The feeding section …

The Effect Of Moox Reducibility On Its Activity For Anisole Hydrodeoxygenation, Chantal Walker

Electronic Thesis and Dissertation Repository

Catalytic hydrodeoxygenation (HDO) is a process for upgrading crude bio-oil as it has a high oxygen content which causes several undesirable properties. Current methods for HDO use sulfided NiMo and CoMo or supported noble metal catalysts which hydrogenate aromatic rings, leading to less valuable products and increasing the hydrogen consumption. Using 10 wt. % MoO3 supported on ZrO2, TiO2, γ-Al2O3, SiO2 and CeO2, we investigated the atmospheric HDO of anisole, a model compound, at 350 °C. All catalysts achieved C – O bond cleavage, preserving the aromatic ring. In situ UV-Vis spectroscopy showed a peak corresponding to intervalence charge transfer …

Fluidization Characteristics Of Group C+ Particles: Fine Powder With Nanoparticle Modulation, Yandaizi Zhou

Electronic Thesis and Dissertation Repository

Geldart Group C particles become increasingly attractive in industry because of their small particle sizes and large specific surface areas. The main challenge in the flow and fluidization of Geldart Group C particles is their cohesive nature due to strong interparticle forces. The “nanoparticle modulation” technique was adopted to reduce the interparticle forces of Group C particles and thus significantly improved their flow and fluidization quality. Group C⁺ particles, a new type of fine particles with drastically reduced or insignificant interparticle forces, were created using the nano-modulation technique.

Fundamental studies provided a comprehensive understanding of the fluidization quality of …

Thermo-Catalytic Decarboxylation Of Fatty Acids And Real-World Derivatives Towards Liquid Fuels, Shaun J. Fraser

Electronic Thesis and Dissertation Repository

The production of green diesel through waste fats and oils is a promising route to producing renewable transportation fuels that are energy dense, have low oxygen content, low nitrogen content, and possess excellent cold flow properties. However, producing green diesel can be expensive, as most methods use expensive noble metals catalysts such as platinum or palladium, use expensive hydrogen gas, and/or use pyrolysis and thermal cracking to reduce hydrocarbon chain length and lose energetic carbon-hydrogen bonds. This thesis studies the continuous thermo-catalytic decarboxylation of fatty acids and their derivatives to create liquid transportation fuels using an inexpensive MoO_x/Al …

Bubble Dynamics In A Sand Fluidized Bed In The Presence Of Biomass Pellets, Nicolas Torres Brauer

Electronic Thesis and Dissertation Repository

Given the worldwide concerns regarding fossil fuel availability, global warming, water, and air pollution and economy needs, there is an urgent requirement to develop and implement alternative energies. Biomass gasification can consume vegetal waste to produce syngas, which is a mix of carbon monoxide, hydrogen, and carbon dioxide. When biomass gasification is carried out in a fluidized bed, the process is highly efficient.

The experimental study of the present Ph.D. dissertation took place in a Plexiglas 0.44 m diameter unit, equipped with a CREC Optiprobe system and a video camera. The unit was filled with 200-900 µm sand particles and …

Improvement Of Fluidization Ability For Group A Powders By Fine Powder Additives, Xiaowei Zhang

Electronic Thesis and Dissertation Repository

Group A powders are widely utilized in the industry because of the great quality of fluidization, which can be affected by the fine content. This project investigates the feasibility that employing the fine powders (≤ 20 μm) as additives to further improve the fluidization ability of Group A powders. Three additives, Coal-15, GB-6, and SiO₂-5 are added into FCC-76, based on various volume fractions. The minimum fluidization velocity (U_mf), bed expansion ratio (BER), and dense phase expansion ratio (DER) are tested to evaluate the quality of fluidization. Coal-15 can slightly improve the fluidization quality. High …

Hydrodynamics Of Liquid-Solid And Three-Phase Inverse Circulating Fluidized Beds, Tian Nan

Electronic Thesis and Dissertation Repository

The hydrodynamics of inverse liquid-solid circulating fluidized bed (ILSCFB) is experimentally studied in a 5.4 m tall and 0.076 m ID column. 5 types of low density particles are investigated with different particle terminal velocities.

Solids holdup distribution is found to be uniform in a wide range of superficial liquid velocities and over 10 solid circulation rates. Average solids hold is not sensitive to particle properties. Clustering phenomenon is found to be significant affecting the slip velocity in the ILSCFB. And the cluster phenomenon is directly related to particle R_­eynolds number (R_et). Particles with little …

Experimental Investigations On The Instantaneous Flow Structure In Circulating Fluidized Beds, Xiaoyang Wei

Electronic Thesis and Dissertation Repository

Knowing the instantaneous flow structure is of great importance for the understanding of gas-particle interaction and for the prediction of reactor performances. In this thesis, a systematic and comprehensive study has been conducted on the instantaneous flow structure in a narrow rectangular riser (19 mm in thickness, 114 mm in width and 7.6 m in height), in a cylindrical riser (76 mm in diameter, 10.2 m in height) and in a cylindrical downer (50 mm in diameter, 4.9 m in height). A wider range of operating conditions has been achieved in risers and downer with superficial gas velocity from 3.0 …

Propane Oxidative Dehydrogenation Under Oxygen-Free Conditions Using Novel Fluidizable Catalysts: Reactivity, Kinetic Modeling And Simulation Study, Samira Rostom

Electronic Thesis and Dissertation Repository

Propane oxidative dehydrogenation (PODH) was studied using VO_x/γAl₂O₃ and VO_x/ZrO₂-γAl₂O₃ (1:1 wt.%) catalysts, as well as consecutive propane injections under oxygen-free conditions. These catalysts were synthesized with 2.5, 5 and 7.5 wt.% vanadium loadings, and prepared using a wet saturation impregnation technique. Different characterization techniques were used to establish catalyst properties including NH₃-TPD, pyridine FTIR and NH₃-TPD kinetics. As well, PODH runs in the CREC Riser Simulator were developed under oxygen free atmospheres at 500-550°C, close to 1 atm., 10-20 s and 44.0 catalyst/propane …

Electrocatalysts With High Activity And Stability For Polymer Electrolyte Membrane Fuel Cells, Zhongxin Song

Electronic Thesis and Dissertation Repository

In addressing the activity and durability challenges facing electrocatalysts in polymer electrolyte membrane fuel cells (PEMFCs), atomic layer deposition (ALD) is emerging as a powerful technique for deposition of noble metals and transition metal oxides due to its exclusive advantages over other methods. The primary advantages of ALD are derived from the sequential, self-saturating, gas-surface reactions, and angstrom level control that take place during the deposition process. Therefore, ALD possesses the advantage in precisely control the particle size and uniform distribution on the substrate. By forming chemical bonds between the initial layer of ALD precursor and support atoms during the …

Hydrogen Production By Photocatalytic Water Splitting Under Near-Uv And Visible Light Using Doped Pt And Pd Tio2, Bianca Rusinque

Electronic Thesis and Dissertation Repository

Photocatalysis is a promising methodology for hydrogen production. It involves the use of an unlimited source of energy, sunlight, and a semiconductor material to split water with zero carbon emissions.

This Master’s thesis reports high efficiencies in terms of hydrogen production via water splitting using 2.0v/v% ethanol as scavenger, platinum and palladium as noble metals on TiO₂ photocatalysts at three metal loadings (1.0, 2.5 and 5.0wt%). Both near UV and visible light were used in the studies developed. These photocatalysts were synthetized using a sol-gel method whose morphological properties were enhanced due to the presence of soft template precursors. …

Numerical Investigations Of Bubble Column Equipped With Vertical Internals In Different Arrangements, Tuntun Gaurav

Electronic Thesis and Dissertation Repository

Bubble columns are multiphase contactors with wide applications in industrial processes. Often they are equipped with longitudinal tube bundles to facilitate heat exchange. Studying effects of these internals on column hydrodynamics is vital for the design of these internals. Computational Fluid Dynamic (CFD) simulations provide an understanding of the complex two-phase flow enabling the study of the effects of the internals on the column hydrodynamics. In the present work, an Eulerian-Eulerian based two-fluid model (TFM) coupled with a population balance model (PBM) is used to simulate the gas-liquid two-phase flows in bubble columns. The models studied were validated using experimental …

Production Of Monomeric Aromatics/Phenolics From Hydrolysis Lignin (Hl) By Catalytic Fast Pyrolysis And Hydrothermal Liquefaction, Hooman Paysepar

Electronic Thesis and Dissertation Repository

Bio-oil, produced from bio-feedstocks by thermochemical conversion technologies (e.g., pyrolysis or direct liquefaction), can be renewable replacement for petroleum for energy and chemical production. However, bio oil has high oxygen content, low stability, and low heating value. Thus, upgrading of bio-oil is necessary to remove the oxygen and make it a suitable substitute for conventional liquid transportation fuels or for value-added bio-based chemicals. Oxygen in a bio-oil can be removed by catalytic cracking or hydro-de-oxygenation to the form of H₂O, CO and CO₂ in the presence of a catalyst.

The overall objective of this PhD project was …

Hydrogen Generation From Eosin Y-Sensitized Pt/Zno Under Solar Light Irradiation, Tianfang Tian

Electronic Thesis and Dissertation Repository

Hydrogen is a promising alternative energy carrier. Generating hydrogen via photocatalysts is clean and energy saving comparing to the current technology for hydrogen generation. ZnO has been proved to have photocatalytic activities for wastewater treatment by multiple studies. However, there are not enough studies to investigate its potential to generate hydrogen as the photocatalyst under light irradiation. Therefore, we will investigate the photocatalytic ability of Pt/ZnO to generate hydrogen. Triethanolamine (TEOA) was used as sacrificial reagent while Eosin Y was used as sensitizer. Pt/ZnO was characterized and tested for its activity for hydrogen generation in different conditions, which are platinum …

Co2 Biomass Fluidized Gasification. Thermodynamic And Reactivity Studies., Amanda Kuhn Bastos

Electronic Thesis and Dissertation Repository

This study reports biomass gasification in a CREC Riser Simulator under thermal and catalytic conditions. Steam-CO₂ and steam-inert were used as gasifier agents. Biomass feedstocks and a model compound were employed to evaluate gasification performance. It was proven that catalytic steam-CO₂ gasification significantly reduces tar formation while improving carbon conversion to syngas.

Experimental results were compared with thermodynamic equilibrium model predictions. This model accounts for biomass composition, bed temperature and gasifying agents. The model predictions are close to experimental results for steam-CO₂ gasification, leading to a zero CO₂ gain.

2-methoxy-4-methylphenol and 20%Ni-5%CeO₂/γ-Al₂O …

Syngas Chemical Looping Combustion Using A Fluidizable Oxygen Carrier: Reactivity, Kinetics, Reactor Simulation, Imtiaz Ahmed

Electronic Thesis and Dissertation Repository

Biomass gasification yields a blend of H₂, CO, CH₄ and CO₂, designated as syngas. Syngas can be further combusted using fluidizable oxygen carriers (OCs) during power generation via Chemical Looping Combustion (CLC). To improve syngas CLC and establish its application, a new Ni-based oxygen carrier with a Co and La modified γ-Al₂O₃ support was studied. This type of OC considerably limits the NiAl₂O₄ formation. Therefore, the oxygen carrier was engineered using a special preparation methodology to eliminate NiAl₂O₄ species formation. This promising Highly Performing Oxygen Carrier …

Photocatalytic Hydrogen Production Using A Mesoporous Tio2 Doped With Pt: Semiconductor Synthesis, Oxidation-Reduction Network And Quantum Efficiencies., Jesus Fabricio Guayaquil-Sosa

Electronic Thesis and Dissertation Repository

The present PhD dissertation establishes that hydrogen can be produced using mesoporous TiO₂ as a photocatalyst, doped with platinum atoms (Pt), in a slurry medium, under near-UV irradiation and with ethanol as a sacrificial reagent (scavenger). These mesoporous TiO₂ photocatalysts were prepared using a sol-gel method. The mesoporous Pt-TiO₂ photocatalyst displayed a reduced 2.34 eV band gap compared to the bare TiO₂ (3.20 eV).

Photocatalytic hydrogen production experiments were performed in a Photo-CREC Water II Reactor (PCW-II Reactor). This novel unit provides both radial and axial symmetrical irradiation profiles. Furthermore, macroscopic energy balances developed in this …

Fabrication And Modification Of Titania Nanotube Arrays For Harvesting Solar Energy And Drug Delivery Applications, Ahmed El Ruby Abdel Rahman Mohamed

Electronic Thesis and Dissertation Repository

The fast diminishing of fossil fuels in the near future, as well as the global warming caused by increasing greenhouse gases have motivated the urgent quest to develop advanced materials as cost-effective photoanodes for solar light harvesting and many other photocatalytic applications. Recently, titania nanotube arrays (TNTAs) fabricated by anodization process has attracted great interest due to their excellent properties such as: high surface area, vertically oriented, highly organized, one-dimensional, nanotubular structure, photoactivity, chemical stability and biocompatibility. This unique combination of excellent properties makes TNTAs an excellent photoanode for solar light harvesting. However, the relatively wide band gap energy of …

Hydrodeoxygenation Of Anisole In A Novel Externally Agitated Reactor, Brett Pomeroy

Electronic Thesis and Dissertation Repository

Bio-oil upgrading via hydrodeoxygenation (HDO) was investigated using anisole, a model compound, in a novel Externally Agitated (EA) reactor which is expected to enhance gas-liquid-solid mixing. Operating conditions were established based on anisole HDO with 10 wt.% Ni on silica, γ-alumina, and δ-alumina while varying temperatures between 160 to 280^oC, and reaction times between 30 – 90 minutes. Mild temperatures of 220^oC and 45 minutes for reaction time with γ-alumina were selected for subsequent work since γ-alumina demonstrated the highest HDO activity. HDO was then investigated with varying Ni-Cu and Ni loadings. Despite the improved reducibility …

Hydrothermal Decarboxylation Of Fatty Acids And Their Derivatives For Liquid Transportation Fuels, Md Zakir Hossain

Electronic Thesis and Dissertation Repository

Due to the depletion of fossil fuel reserves, renewable resources are required to produce tomorrow’s fuel range hydrocarbons. This thesis focuses on the hydrothermal decarboxylation of fatty acids and their derivatives derived from renewable sources. These are required for liquid transportation fuels which have similar properties to conventional fuels. Detailed catalytic studies were performed for the decarboxylation of oleic acid as a model compound and corn distiller’s oil (CDO) as a real feedstock. Commercial activated carbon and laboratory prepared Ni-Al₂O₃, MgO-Al₂O₃, Mo-Al₂O₃ catalysts were also examined as catalysts. Fatty …

Hydrodynamics In The Gas-Driven Inverse Liquid-Solid Fluidized Bed, Jiaqi Huang

Electronic Thesis and Dissertation Repository

A novel reactor named Gas-Driven Inverse Liquid-Solid Fluidized Bed (GDFB for short) was developed in this research. A vertical baffle divides the column into a riser and a downer. Inverse fluidization is driven by the gas and occurs in the downer, where hydrodynamics and their influencing factors were studied. In the solid-baffle system, four fluidization regimes were observed, including the packed bed, semi-fluidized bed, fully-fluidized bed, and circulating bed. Bed expansion ratio was higher for particles with a higher density and a smaller solids loading. Moreover, the average particle velocity was proportional to superficial gas velocity and higher for denser …

Photoactive Properties Of Nanostructured Titania Modified Polyurethanes, Chao Chen

Electronic Thesis and Dissertation Repository

In order to enhance both the photoactivity and physical/mechanical properties of titania/polyurethane (PU) nanocomposites, in-situ polymerization and film casting were investigated. Both self-degrading PU foams and self-cleaning PU coatings were prepared. Functional monomers were prepared usingDMPA (2,2-dimethylolpropionic acid) functionalized anatse TiO₂ and P25 for integration into polyurethane foam with a "grafting-from" synthetic method. This technique was found to successfully reduce the agglomeration effect of titania nanoparticles inside the foams. In addition, the photodegradation rate was enhanced by > 120% over unmodified foam at an optimized loading of 3wt% DMPA functionalized anatase TiO₂. The presence of DMPA functionalized P25 …

Multi-Objective Optimization Of Industrial Ammonia Synthesis, Stanislav Ivanov

Electronic Thesis and Dissertation Repository

The thesis describes modelling and optimization work of an industrial ammonia synthesis. Author developed first-principle mathematical model of the commercial converter based on gas-solid reaction and heat transfer within the system. The model is validated with industrial data and showed satisfactory accuracy. Further, optimization study is performed in multi-objective manner to intensify ammonia production and decrease heat duty of the process. Result have revealed a potential to improve current operating condition int terms of both objectives.

Supercritical Fluid Extraction Of Valuable Chemicals: Application Of Microalgae And Pyrolysis Oil As Feedstocks, Osariemen Ogbeide

Electronic Thesis and Dissertation Repository

In this dissertation, pure and modified carbon dioxide were used as non-conventional solvents for the investigation of lutein, chlorophyll a, chlorophyll b extraction from microalgae and for caffeine extraction from the pyrolysis oil of spent coffee grounds. The use of toxic organic solvents in supercritical fluid extraction has propelled research efforts to develop new solvents that are environmentally friendly and provide faster extraction compared to conventional extraction processes. For this reason, phosphatidylethanolamine (PE), a major phospholipid consisting of 14% of the entire soybean lecithin was acetylated with acetic anhydride, providing a surfactant (N-A-PE).

Then, the synthesized N-A-PE was employed as …