This paper studies castor oil’s potential as a biodiesel feedstock. Base-catalyzed transesterification batch reactions were conducted at various experimental conditions while measuring the concentration of the reaction components over time. A gas chromatograph with a flame-ionization detector analyzed these samples. A factorial design of experiments was used to determine how conversion was affected by reaction temperature, sodium methoxide concentration, and ratio of methanol to oil. Conversion was maximized (0.9964) at 30 °C, 0.5% catalyst, and 9:1 molar ratio. The concentration data were used to study the reaction kinetics. Modeling the reaction as three equilibria yielded six rate constants. These values indicate that castor oil transesterifies faster than soybean oil. The fuel properties were determined by ASTM D 6751. Viscosity was excessively high, but specifications were met for the remaining tests. Despite the promising yield and kinetics of the reaction, the fuel viscosity limits castor oil’s viability as a biodiesel feedstock.

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The need for sustainability has been on the rise. Municipalities are finding ways of reducing waste, but also finding ways to reduce energy costs. Waste-to-energy is a sustainable method that may reduce bio-solids volume while also producing energy. In this research study bio-solids enters a bubbling bed gasifier and within the gasifier a synthesis gas is produced. This synthesis gas exits through the top of the gasifier and enters a thermal oxidizer for combustion. The thermal oxidizer has an innovative method of oxidizing the synthesis gas. The thermal oxidizer has two air injection sites and the possibility for aqueous ammonia injection for further NOx reduction. Most thermal oxidizers already include an oxidizer such as air in the fuel before it enters the thermal oxidizer; thus making this research and operation different from many other thermal oxidizers and waste-to-energy plants. The reduction in waste means less volume loads to a landfill. This process significantly reduces the amount of bio-solids to a landfill. The energy produced from the synthesis is beneficial for any municipality, as it may be used to run the waste-to-energy facility. The purpose of this study is to determine methods in which operators may configure future plants to reduce NOx emissions. NOx mixed with volatile organic compounds (VOC) and sunlight, produce ozone (O3) a deadly gas at high concentrations. This study developed a model to determine the best methods to reduce NOx emissions. Results indicate that a fuel-rich then fuel-lean injection scheme results in lower NOx emissions. This is because at fuel-rich conditions not all of the ammonia in the first air ring is converted to NOx, but rather a partial of the ammonia is converted to NOx and N2 and then the second air ring operates at fuel-lean which further oxidizes the remaining ammonia which converts to NOx, but also a fraction to N2. If NOx standards reach more stringency then aqueous ammonia injection is a recommended method for NOx reduction; this method is also known as selective non-catalytic reduction (SNCR). The findings in this study will allow operators to make better judgment in the way that they operate a two air injection scheme thermal oxidizer. The goal of the operator and the organization is to meet air quality standards and this study aims at finding ways to reduce emissions, specifically NOx.

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Controlling the size and size distribution of colloidal nanoparticles have gained extraordinary attention as their physical and chemical properties are strongly affected by size. Ligands are widely used to control the size and size distribution of nanoparticles; however, their exact roles in controlling the nanoparticle size distribution and the way they affect the nucleation and growth kinetics are poorly understood. Therefore, understanding the nucleation and growth mechanisms and developing theoretical/modeling framework will pave the way towards controlled synthesis of colloidal nanoparticles with desired sizes and polydispersity. This dissertation focuses on identifying the possible roles of ligands and size on the kinetics of nanoparticle formation and growth using in-situ characterization tools such as small-angle X-ray scattering (SAXS) and kinetic modeling. The presented work further focuses on developing kinetic models to capture the main nucleation and growth reactions and examines how ligand-metal interactions could potentially alter the rate of nucleation and growth rates, and consequently the nanoparticle size distribution. Additionally, this work highlights the importance of using multi-observables including the concentration of nanoparticles, size and/or precursor consumption, and polydispersity to differentiate between different nucleation and growth models and extract accurate information on the rates of nanoparticle nucleation and growth. Specifically, during the formation and growth of colloidal nanoparticles, complex reactions are occurring and as such nucleation and growth can take place through various reaction pathways. Therefore, sensitivity analysis was applied to effectively compare different nucleation and growth models and identify the most important reactions and obtain a reduced model (e.g. a minimalistic model) required for efficient data analysis. In the following chapters, a more sophisticated modeling approach is presented (population balance model) capable of capturing the average-properties of nanoparticle size distribution. PBM allows us to predict the growth rate of nanoparticles of different sizes, the ligand surface coverage for each individual size, and the parameters involved in altering the size distribution. Additionally, thermodynamic calculations of nanoparticle growth and ligand-metal binding as a function of size and ligand surface coverage were conducted to further shed light on the kinetics of nanoparticle formation and growth. The combination of kinetic modeling, in-situ SAXS and thermodynamic calculations can significantly advance the understanding of nucleation and growth mechanisms and guide toward controlling size and polydispersity. / Doctor of Philosophy / The synthesis of colloidal metal nanoparticles with superior control over size and size distribution, and has attracted much attention given the wide applications of these nanomaterials in the fields of catalysis, photonics, and electronics. Obtaining nanoparticles with desired sizes and polydispersity is vital for enhancing the consistency and performance for specific applications (e.g., catalytic converters for automotive emission). Ligands are often employed to prevent agglomeration and also control the nanoparticle size and size distribution. Ligands can affect the precursor reactivity and therefore the reduction/nucleation by binding with the metal precursor. Nucleation refers to the assimilation of few atoms to form initial nuclei acting as templates for nanoparticle growth. Additionally, ligands can bind with the nanoparticle surface sites and change the rate of surface growth and therefore the final nanoparticle size. Despite strong effects of ligands in the colloidal nanoparticle synthesis, their exact role in the nucleation and growth kinetics is yet to be identified. Additionally, nucleation and growth models capable of unraveling the underlying mechanisms of nucleation and growth in the presence of ligands are still lacking in the literature. Therefore, obtaining nanoparticles with desired sizes and polydispersity mostly relies on trial-and-error approach making the synthesis costly and inefficient. As such, developing models capable of predicting suitable synthesis conditions is contingent upon understanding the chemistry and mechanism involved during nanoparticles formation. Therefore, in this study, novel kinetic models were developed to capture the nucleation and growth kinetics of colloidal metal nanoparticles under different synthetic conditions (different types of solvents, different concentrations of ligand and metal). In-situ SAXS was further employed to measure the average diameter, concentration of nanoparticles, and polydispersity during the synthesis and extract the nucleation and growth rates (evolution of concentration of nanoparticles and size). First, an average-property model was developed to account for ligand-metal bindings and capture the size and concentration of nanoparticles during the synthesis. Then, a more complex modeling approach; PBM, accompanied by the thermodynamic calculations of surface growth and ligand-nanoparticle binding enthalpies was implemented to capture the size distribution. As it will be shown later, the determination of the underlying mechanisms resulted in a highly predictive kinetic model capable of predicting the synthetic conditions to obtain nanoparticles with desired sizes. The proposed methodology can serve as a powerful tool to synthesize nanoparticles with specific sizes and polydispersity.

Chemical engineering, as a discipline, uses knowledge of chemistry, thermodynamics, and transport to process and refine resources on a global scale. The chemical processing industry has an enormous impact on global energy consumption and contributes to climate change. Chemical engineers play a major role in the transition of the chemical industry away from fossil fuels and develop more sustainable and efficient methods to produce commodities. To achieve this goal, new chemical and processing technologies must be developed. It is critical in these early stages of development to identify chemical and processing pathways that are both practical and economically competitive to existing technologies. With the goal of increasing the speed of developing and implementing new chemical and processing technologies, screening and early stage evaluation is essential to guiding research towards the most promising new processes and chemical pathways. This work focuses on the investigation of new chemical processing technologies, which have received academic attention, but have not been evaluated in the context of practical implementation, process design, or energy consumption. We investigate the background of these new technologies and compare them to the conventional counterparts. We present chemical and operational insights gained from industrial patents to develop feasible process designs that inform the operation and demonstrate drastic improvements possible with established heat integration and process intensification techniques. One technology we investigate is aromatics separation from petroleum feedstocks using new ionic liquid (IL) solvents. ILs are very popular in literature to replace conventional organic solvents with their main novelty being non-volatility. A practically limitless number of ILs with different properties can be synthesized introducing the potential to develop IL solvents tailored to specific applications. We investigate the potential of ILs for aromatic extraction by first developing a methodology to model the process and capture molecular interactions between the solvent and typical hydrocarbons. We then developed an IL specific process design that overcomes the challenges related to the target feedstock. We finally determined the ideal IL solvent properties for the target application investigated. We simulate and optimize designs considering 16 different ILs and use the data to correlate solvent properties to key process variables and total process energy demand. We demonstrate that 11 of the 16 ILs require less energy compared to the conventional solvent with the best performing IL reduced energy demand by 43%. Another technology we investigate is chemical recycling of poly(ethylene terephthalate) (PET), commonly used in bottles, textiles, and packaging. Chemical recycling converts waste PET into monomers that can be reprocessed into PET polymer. The monomer products are easier to purify, and chemical recycling expands the scope of recyclable waste material. There are three PET chemical recycling pathways considered by industry and academia: glycolysis, methanolysis, and hydrolysis. We investigate the fundamental differences between these chemical pathways and highlight how differences in physical and chemical properties of reactants and products lead to processing differences. We use a combination of industrial literature review and design knowledge to develop the first complete process configurations for each depolymerization pathway. We demonstrate heat integration and process intensifications that drastically reduce energy demand. We use the combination of process design and literature to compare the designs and discuss uncertainties and advantages and disadvantages. Heat integrated continuous PET chemical recycling processes can be expected to consume between 6,000 – 10,000 kJ/kg PET regardless of the depolymerization route. Continuing the trend of investigating chemical recycling of polymers we consider nylon 6, the most widely produced polyamide used for electronics, automotive parts, and textiles. Nylon 6 polymer is readily converted to its monomer caprolactam with or without the use of water as a solvent. While the recycling of post-consumer nylon 6 waste has been limited, the recovery and recycling of nylon 6 scrap and oligomers is well known. We identify the three processing routes commonly used to produce caprolactam from nylon 6: liquid-phase hydrolysis, steam stripping, and solvent-free depolymerization. We identify decomposition reactions and use experimental data to develop a kinetic model for nylon 6 depolymerization. We incorporate the kinetic model into process models for the different processing routes and demonstrate novel process intensifications to drastically reduce energy demand. We compare and discuss potential applications for each process configuration processing different types of post-consumer waste. Concluding the topic of chemical recycling of polymers, we investigate nylon 66 depolymerization, which despite chemical similarities to nylon 6, is hardly considered for chemical recycling. We provide an overview of the different chemical recycling pathways proposed in literature including acid and alkaline hydrolysis, and ammonolysis. We use experimental data to develop a novel activity coefficient based kinetic model for nylon 66 hydrolysis and add degradation reactions to present the first alkaline hydrolysis process design for nylon 66. We investigate different sections of the process and operation sensitivity to design assumptions and provide a comparison to the similar PET alkaline hydrolysis process. We find the nylon 66 alkaline hydrolysis process has favorable energy demand and is deserving of further evaluation for commercial implementation. Overall, this work has advanced the aromatic extraction technology and chemical recycling of step growth polymers. We demonstrate broad and systematic methods of incorporating data from academic and industrial evaluations to produce practical and thermodynamically consistent process models. We use these models to describe the reactions, separations, and purifications of new technologies to quantify energy demands and where operational or data uncertainties exist to focus future research. We use the defined process flows and separations to demonstrate process intensifications that drastically reduce process energy demand by as much as 70%, which can alter conclusions and favorability of certain process configurations. / Doctor of Philosophy / Chemical engineering plays a critical role in the global efforts to transition from fossil fuels to renewable and sustainable resources. This includes improving energy efficiency of existing chemical processes, improving processes to consume less raw materials, and developing new pathways to produce chemicals traditionally derived from fossil fuels. Academic chemical engineering research focuses on developing new chemicals and chemical processes to aid in this effort. There are a vast number of new chemicals and processes investigated in academia, but it is extremely rare that these advance beyond a conceptual or lab-scale, which limits the contribution of the research towards solving the problems it aims to address. We use our expertise in process design, modeling, and the general ability to understand how technology advances from concept to implementation. We take new chemicals or reaction pathways and conceptualize practical designs or implementations of the technology at commercial scale. We use the development of the designs to rank and screen favorability of new technologies against other new or conventional technologies, approximate the relative complexity and resource consumption, and identify important parts of the process where data is critical for continued development or a more accurate assessment of technological viability. In this way, we guide research for new technologies to increase the speed and likelihood of real-world implementation and impact. In this dissertation, we consider the application of a new type of solvents, claimed to be 'green', that are used to separate petroleum products, and recycling processes for plastics that convert the plastic to chemicals, which are purified and converted back to the original plastic. The results of our work demonstrate the new type of solvents we investigated have properties that can reduce the energy demand of the process for which they are proposed by almost 50% using a novel design concept we developed. Despite the potential of these solvents, we raise concerns about uncertainties related to their practical implementation that require resolution. For the chemical recycling of plastics, we demonstrate a disconnect between academic focus and industrial practice. We develop some of the first models for several waste plastic chemical recycling processes to demonstrate how the plastics are chemically converted and purified to be suitable for consumer use. We compare different methods to recycle specific types of plastic, providing insight into the advantages and disadvantages of each method, considering applications for which they are most suitable, and indicating where further research is best applied. We demonstrate that these processes, using advanced processing techniques, can drastically reduce energy demand, in some cases by as much as 70%.

La pyrolyse et la gazéification sont les deux procédés les plus prometteurs pour une valorisation thermique des déchets organiques solides en réponse aux objectifs énergétiques environnementaux actuels et futurs. Si pour la pyrolyse, les déchets traités sont aussi synthétiques (plastiques, composites) que naturels (biomasse), pour la gazéification c'est la biomasse qui est la matière première la plus rencontrée. Les travaux expérimentaux de cette thèse ont été réalisés dans deux types d'installations : une installation à échelle laboratoire (analyseur thermique : TG, ATD, EGA) et une installation à échelle pilote (nommée four « Aubry »). Les traitements thermiques ont été effectués dans les conditions spécifiques pour la pyrolyse (atmosphère d'azote) et la gazéification (vapeurs d'eau). Les matériaux testés ont été le polychloroprène, les composés de la biomasse (hémicellulose, lignine, cellulose), seuls où en mélange, ainsi qu'un bois naturel (le bouleau) et son « modèle » (mélange en proportions équivalents de ses constituants). Deux modèles cinétiques pour la pyrolyse du polychloroprène ont été choisis de littérature et testés. La différence primordiale entre les deux modèles est leur degré de complexité. Le premier est un modèle empirique simplifié, tandis que le deuxième, très détaillé, est un modèle radicalaire Le modèle cinétique utilisé pour modéliser le processus de pyrolyse de la cellulose, pris aussi de la littérature, a montré une concordance très bonne avec nos résultats expérimentaux. L'étude hôte de la gazéification à la vapeur d'eau a nécessité des modifications de nos installations expérimentales, tout particulièrement à l'échelle pilote, pour assurer une atmosphère confinée en vapeur d'eau. Les expériences réalisées en conditions expérimentales spécifiques ont données des résultats excellents pour la composition finale du gaz de synthèse. La simulation, à l'échelle pilote, de la gazéification a été obtenue par adaptation d'un modèle existant, à la réalisation de nos conditions opératoires, prenant en compte les transferts matières et basé sur l'évolution de la porosité d'une particule sphérique équivalente. Le modèle a montré une concordance raisonnable avec nos données expérimentales. La dernière partie de cette thèse présente une étude dans lequel on compare les analyses thermiques pour les constituants purs, un modèle de bois et un bois naturel afin d'établir les interactions possibles entre ces composants lors de la dégradation thermique du bois naturel. Les résultats ont montré que pour les mélanges cellulose-lignine et lignine-hémicellulose, le premier composé inhibe la dégradation du dernier tandis que, pour les mélanges cellulose-hémicellulose, cet effet se manifeste à l'inverse. Tous les modèles testés et les résultats enregistrés dans cette thèse représentent des instruments très utiles pour l'aide au dimensionnement des installations de pyrolyse à échelle laboratoire ainsi que pour des installations de gazéification à la vapeur d'eau à échelle pilote. / The pyrolysis and gasification are the most actual techniques used for valorization of organic wastes. If for pyrolysis the raw materials are both synthetic (plastics) and natural (biomass), in the case of gasification mainly the biomass is used. The experiments presented in this thesis were carried out in two type of plants: a laboratory scale plant (thermal analyses: TGA, DTA, EGA) and a pilot scale plant (so-called “Aubry” furnace). The thermal treatments implemented both the conditions of pyrolysis (nitrogen atmosphere) and gasification (water vapors). The materials tested in the experimental part were: polychloroprene, biomass constituents (hemicelluloses, lignin and cellulose), alones and in mixture, and a natural wood (the birch) with it's “model” (a mixture of it's components in different proportions). For the polychloroprene pyrolysis, two kinetic models chosen from the published literature were tested. The difference in the two models is given by their degree of complexity. The first one was a simplified empirical model. The second one was a free-radical model. For the cellulose pyrolysis was also tested a model proposed in the literature and the model showed a good accuracy in representing our experimental data. The study of gasification at pilot scale needed an appropriate modification of the experimental set-up to create a saturated atmosphere in water vapor inside the Aubry furnace. The experimental work concerning the gasification followed a specific protocol and gave excellent results for the syngas composition. A gasification mathematical model for pilot scale was proposed and tested. This model, based on the evolution of equivalent spherical particles porosity, take supplementary into account the mass transfer. The results given by the last model were in reasonable agreement with our experimental results. The last part of this thesis presents a comparative study of the thermal analyses of pure biomass components, of a wood model and also of a natural wood. The goal is to identify the interactions that could take place between these compounds during the thermal degradation of the natural wood. Our results showed that for the mixtures cellulose-lignin and lignin-hemicelluloses the first compound inhibits the second one. For the mixtures cellulose-hemicelluloses this effect is inverse. All the kinetic models tested in this thesis are useful tools for dimensioning laboratory scale pyrolysis plants and pilot scale set-up for water vapors gasification.