Continuous flow reaction using micro-reactors is a valued technology due to its excellent mass and heat transfer performance, reduced reactor volume, handling capacity of hazardous reactions, and many other process intensifications. These intensifications opportunities interest the fine chemicals, pharmaceuticals producers and other multiphase reaction users who currently use batch processes or already use continuous flow. In this thesis, elements of passive and active mixing are investigated for the application of immiscible liquid-liquid systems. In the first study, the effects of geometrical arrangements of a residence time between mixing units on the interphase mass transfer rates are evaluated with four different immiscible liquid-liquid systems. A presentation of an algorithm for the optimal selection of a reactor and its operating conditions is given in order to enable easy and improved use of one’s micro-reactor. In the second study, the impact of a secondary pulse flow on interphase mass transfer is investigated. A coil without internal baffles is used as the oscillatory-flow coil reactor with a continuous active mixing source. The best application for the reactor is determined using a comparison to other complementary continuous flow platforms in the toolbox approach. The novel advancements presented here will help lead new molecular discoveries and connect the laboratory science scale to the process engineering production scale.

Cyclic volatile methyl siloxanes (cVMS) are anthropogenic chemicals present in a range of consumer personal care products such as antiperspirants and lotions. They are highly volatile, and readily released to the atmosphere by personal care product use. Generally unreactive, they are found in high concentrations in indoor environments, and transported long distances in the atmosphere. A major removal pathway for these silicon-containing gases is reaction with the OH radical, which has been recently shown to yield secondary Si-containing aerosol compounds in addition to the gas phase products. Despite the significance of the atmospheric fate of these compounds, much of the previous work has focused on the aquatic fate, and almost exclusively on the parent compounds. The oxidation products and potential aerosol species have received much less attention, with almost no ambient measurements or experimental physical property data. This work investigates cVMS with a focus on providing much needed information on potential loadings of the oxidation products, their distribution, and particle phase properties using an atmospheric model and laboratory experiments. Specifically, cVMS was added to the Community Multiscale Air Quality (CMAQ) model; expected concentrations, spatial distribution, and seasonal trends were quantified; cVMS secondary aerosols generated and physical properties characterized; and secondary aerosol parameters for atmospheric modeling developed. The CMAQ model code was modified to update the chemical mechanism with cVMS, develop emissions, boundary, and deposition parameters to simulate four separate seasons at a spatial resolution of 36 km over North America. Typical model concentrations showed parent compounds were highly dependent on population density as cities had monthly averaged peak decamethylcyclopentasiloxane (D5) concentrations up to 432 ng m−3. Peak oxidized D5 concentrations were significantly less, up to 9 ng m−3, and were located downwind of major urban areas. Model results were compared to available measurements and previous simulation results. Parent compound concentrations in urban locations were sensitive to transport factors, while parent compounds in rural areas and oxidized product concentrations were influenced by large-scale seasonal variability in OH. Secondary aerosols were formed by reacting cVMS gas in an oxidation flow reactor. The particles were characterized for concentration, size, aerosol yield, morphology, energy-dispersive spectroscopy (EDS) individual particle chemical composition, hygroscopicity (cloud condensation nuclei formation potential), and volatility. Aerosol concentrations were 68 – 220 µg m-3 with aerosol mass fractions (i.e. yields) of 0.22-0.50. Aerosol yield was sensitive to chamber OH, indicating an interplay between oxidation conditions and the concentration of lower volatility species. The D5 oxidation products were non-volatile, with only the smallest particles (10 nm) exhibiting more than 4% of diameter decrease upon heating to 190°C temperature. The D5 oxidation aerosols were relatively non-hygroscopic, with average hygroscopicity kappa of ~0.01. Experimental data was analyzed to develop secondary aerosol parameters for the CMAQ model. Chamber yield data was fit to a two-product Odum volatility model with yield values of 0.14 and 0.82, corresponding to saturation concentrations of 0.95 and 484 µg m-3, respectively. The recommended enthalpy of vaporization is 18 kJ mol-1 based on other modeled secondary organic aerosol. Recommended molecular weights for the D5 low volatility Odum, high volatility Odum, and non-volatile oligomerization species are 588, 373, and 733 g mol-1 corresponding to OH substituted ring-opened, monomer, and dimer species, respectively. This work provides simulations of expected concentrations, spatial patterns, and seasonal influence of the parent and oxidized cVMS species to extend beyond the few parent cVMS measurements and nonexistent oxidation product measurements. The modeling work serves as an important tool to guide future field measurements especially important for the confirmation of particle phase oxidation products. Extensive aerosol characterization measurements provide much needed physical property data important for future modeling, risk, and exposure studies.

Tubular reactors cover a large class of processes in chemical and biochemical engineering. They are typically reactors in which the medium is not homogeneous (like fixed-bed reactors, packed-bed reactors, fluidized-bed reactors,...) and possibly involve diferent phases (liquid/solid/gas). The dynamics of nonisothermal axial dispersion or plug flow tubular reactors are described by semilinear partial differential equations (PDE's) derived from mass and energy balances. The main source of nonlinearities in such dynamics is concentrated in the kinetics terms of the model equations. Like tubular reactors many physical phenomena are modelled by partial differential equations (PDE's). Such systems are called distributed parameter systems. Control problems of these systems can be formulated in state-space form in a way analogous to those of lumped parameter systems (those described by ordinary differential equations) if one introduces a suitable infinite-dimensional state-space and suitable operators instead of the usual matrices. This thesis deals with the synthesis of optimal control laws with a view to regulate the temperature and the reactant concentration of a nonisothermal plug flow reactor model. Several tools of linear and semilinear infinite-dimensional system theory are extended and/or developed, and applied to this model. On the one hand, the concept of asymptotic stability is studied for a class of infinite-dimensional semilinear Banach state- space systems. Asymptotic stability criteria are established, which are based on the concept of strictly m-dissipative operator. This theory is applied to a nonisothermal plug flow reactor. On the other hand, the concept of optimal Linear-Quadratic (LQ) feedback is studied for class of infinite-dimensional linear systems. This theory is applied to a linearized plug flow reactor model in order to design an LQ optimal feedback controller. Then the resulting nonlinear closed-loop system performances are analyzed. Finally this control design strategy is extended to a large class of first-order hyperbolic PDE's systems.

Bioprocessing applications are gaining importance in the traditional chemical industries. With environmental, political, and economical concerns growing, research efforts have recently focused on the substitution of petroleum-derived transportation fuels and materials. As possible products and feedstocks are being investigated, it is important to ensure the new processes are also sustainable. There are several aspects to developing sustainable processes: minimize waste, use environmentally-benign chemicals, find renewable feedstocks, and limit the number of processing steps. This thesis examines ways to enhance the sustainability of bioprocesses. Novel, alternative solvent systems are studied and applied to a variety of bioprocesses. Downstream processing steps and waste can be minimized by designing systems that combine reactions and separations into one process unit. This is accomplished by designing new reactor systems and by replacing currently used solvents. Additional studies, involving analytical techniques that reduce the use of organic solvents, are tested and applied to industrial problems. Finally, new solvent systems are examined for potential processes using renewable carbohydrate feedstock.

xx, 242 p. : ill. (some col.) / Applications of ligand-protected nanoparticles have increased markedly in recent years, yet their controlled synthesis remains an under-developed field. Nanoparticle syntheses are highly specialized in their execution and often possess significant limitations. For example, the synthesis of thiol-stabilized gold nanoparticles (AuNPs) with core diameters greater than 5.0 nm is difficult to achieve using existing methods. This dissertation describes the development of a synthetic strategy for thiolate-stabilized AuNPs over a wide range of core sizes using alkyl thiosulfates (Bunte salts) as ligand precursors. The use of Bunte salts permits the synthesis of larger AuNPs than can be achieved using thiols by allowing the AuNP cores to grow to larger diameters before the formation of the thiolate ligand shell. Chapter II details the development of a direct synthesis strategy using Bunte salts as ligand precursors that produces AuNPs with diameters up to 20 nm. Chapter III describes an investigation of the ligand shell formation that occurs during these syntheses. The ligand shell formation involves the adsorption of the Bunte salt to the AuNP surface, where it is converted to the thiolate. This conversion requires an excess of sodium borohydride in the synthesis of >5 nm AuNPs, but not for the synthesis of smaller AuNPs. This synthetic strategy was adapted for use in flow reactors to attain simultaneous AuNP synthesis and characterization. Chapter IV demonstrates that thiol-stabilized AuNPs can be synthesized in a microfluidic device with product monitoring provided by UV-vis absorbance spectroscopy. The development of a capillary flow reactor that permits the incorporation of new monitoring techniques is presented in Chapter V. The incorporation of Small-Angle X-ray Scattering (SAXS) analysis provides quantitative <italic>in situ</italic> determinations of AuNP diameter. The combination of synthetic control and monitoring makes capillary flow reactors powerful tools for optimization of NP syntheses and monitoring NP growth. In Chapter VI, the capillary flow reactor is used in an investigation of AuNP core growth. We also review AuNP growth mechanisms and show how to differentiate these using SAXS and UV-vis analysis. In these studies, AuNP growth is unexpectedly shown to involve a coalescence mechanism. This dissertation includes previously published and co-authored material. / Committee in charge: Victoria De Rose Chairperson; James E. Hutchison, Advisor; Catherine Page, Member; Darren W. Johnson, Member; Miriam Deutsch, Outside Member

Orientador: Teresa Massako Kakuta Ravagnani / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-17T16:55:35Z (GMT). No. of bitstreams: 1 Possani_Germano_M.pdf: 3312667 bytes, checksum: 30058f7ade4b339ee579a28950283ff8 (MD5) Previous issue date: 2011 / Resumo: Dentre os termoplásticos mais utilizados atualmente na indústria, pode-se mencionar o estireno, principal responsável pela produção de plásticos e borrachas. No processo de fabricação de estireno, a principal rota química é por meio da desidrogenação de etilbenzeno, com o hidrogênio como subproduto. A conversão de etilbenzeno nesta reação é em torno de 50,0 %, devido ao equilíbrio termodinâmico. Para deslocar esse equilíbrio e aumentar a produtividade de estireno,foram desenvolvidas novas configurações de reatores, tal como os reatores com membrana. eatores equipados com membranas de paládio fornecem uma seletividade maisalta ao estireno uando comparados com reatores equipados apenas com membranas porosas. Para explorar o otencial desse tipo de reator, modelagens matemáticas foram desenvolvidas a fim de determinar os parâmetros cruciais que regem esses processos. O objetivo deste trabalho foi modelar e simular um reator de leito fixo catalítico, envolto por uma membrana inerte permseletiva ao hidrogênio com transferência de calor e massa, sendo composta por uma camada de aço inoxidável de 1,6 mm de espessura, a qual serviu de suporte para a deposição de um filme de 20 µm de paládio. Para essa modelagem foram utilizados os métodos de Runge-Kutta-Gill para o cálculo das variáveis no sentido axial, tanto no retentato quanto no permeado, considerando no retentato um leito fixo catalítico descrito pelo modelo Pseudo-homogêneo, e para os cálculos das equações não lineares das frações molares das espécies e do fluxo mássico de hidrogênio na direção radial do reator foi utilizado o método de Newton-Raphson. Foram analisados os perfis de temperatura, pressão e concentração dos componentes da reação axialmente, considerando a transferência de massa e energia através da membrana, além dos valores para a conversão do etilbenzeno e produtividade em relação ao estireno. Como resultados das simulações foram obtidos valores para a conversão e produtividade de 50,3 % e 35,2 %, respectivamente, para o reator na condição de reator de leito fixo catalítico convencional, e 71,2 % e 60,2 %, para o reator na condição de reator de leito fixo catalítico envolto por uma membrana permseletiva ao hidrogênio, sendo estes valores 41,6 % maiores para a conversão do etilbenzeno e 71,0 % maiores para a produtividade em relação ao estireno. Concluiu-se que com a implementação da membrana no reator em estudo, considerando também a troca térmica na membrana, esta é uma boa opção como nova alternativa para o processo de fabricação do estireno / Abstract: Among the most widely used thermoplastics in the industry, styrene can be mentioned, the main responsible for the production of plastics and rubbers. In the manufacturing process of styrene, the principal chemical route is by means of dehydrogenation of ethylbenzene, with hydrogen as a byproduct. The conversion of ethylbenzene in this reaction is around 50,0 % due to thermodynamic equilibrium. To overcome this equilibrium and increase the productivity of styrene, new reactor configurations were developed such as membrane reactors. Membrane reactors equipped with a palladium membrane provide a higher selectivity compared with reactors that are equipped only with a porous membrane. To explore the potential of this type of reactor, mathematical models were developed to determine the crucial parameters governing these processes. The aim of this study was to model and simulate a fixed bed catalytic reactor, surrounded by a permselective to hydrogen inert membrane with heat and mass transfer, composed by a layer of stainless steel of 1,6 mm thickness, which served as support for deposition of a 20 µm film of palladium. For this modeling the Runge-Kutta-Gill method was used to calculate the variables in the axial direction, both in tube side and in permeate side, considering in tube side a catalytic fixed bed described by Pseudo-homogeneous model, and for the calculations of nonlinear equations of the mole fractions of species and the mass flow of hydrogen in the radial direction it was used the method of Newton-Raphson. Profiles of temperature, pressure and concentration of reaction components on axial toward were analyzed considering the heat and mass transfer across the membrane, besides the values for ethylbenzene conversion, selectivity and productivity in relation to styrene. As the simulation results, values were obtained for the conversion and productivity of 50,3 % and 35,2 %, respectively, putting the reactor on condition of conventional catalytic fixed bed reactor, and 71,2 % and 60,2 % for the reactor on condition of catalytic fixed bed reactor surrounded by a permselective membrane to hydrogen, then , the obtained values were 41,6 % higher for the conversion of ethylbenzene and 71,0 % higher for the productivity of styrene. It was concluded that with the implementation of a membrane in reactor under study, also considering the heat transfer in the membrane, this technology is a good option as new alternative to the styrene manufacturing process / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química

Harnessing the Sun’s energy via the conversion of solar photons to electricity has emerged as a sustainable energy source to fulfill our future demands. In this regard, solution-processable, size-tunable PbS quantum dots (QDs) have been identified as a promising active materials for photovoltaics (PVs). Yet, there are still serious challenges that hinder the full exploitation of QD materials in PVs. This dissertation addresses two main challenges to aid these QDs in fulfilling their tremendous potential in PV applications. First, it is essential to establish a large-scale synthetic technique which maintains control over the reaction parameters to yield QDs with well-defined shape, size, and composition. Rigorous protocols for cost-effective production on a scale are still missing from literature. Particularly, previous reports of record-performance QD-PVs have been based on small-scale, manual, batch syntheses. One way to achieve a controlled large-scale synthesis is by reducing the reaction volume to ensure uniformity. Accordingly, we design a droplet-based continuous-flow synthesis of PbS QDs. Only upon separating the nucleation and growth phases, via a dual-temperature-stage reactor, it was possible to achieve high-quality QDs with high photoluminescence quantum yield (50%) in large-scale. The performance of these QDs in a PV device was comparable to batch-synthesized QDs, thus providing a promise in utilizing automated synthesis of QDs for PV applications. Second, it is crucial to study and control the charge transfer (CT) dynamics at QD interfaces in order to optimize their PV performance. Yet, the CT investigations based on PbS QDs are limited in literature. Here, we investigate the CT and charge separation (CS) at size-tunable PbS QDs and organic acceptor interfaces using a combination of femtosecond broadband transient spectroscopic techniques and steady-state measurements. The results reveal that the energy band alignment, tuned by the quantum confinement, is a key element for efficient CT and CS processes. Additionally, the presence of interfacial electrostatic interaction between the QDs and the acceptors facilitates CT from large PbS QD (bandgap < 1 eV); thus enabling light-harvesting from the broad near-infrared solar spectrum range. The advances in this work – from automated synthesis to charge transfer studies – pave new pathways towards energy harvesting from solution-processed nanomaterials.

La gazéification de la biomasse a été étudiée dans les conditions d'un réacteur à flux entraîné, à savoir à vitesse de chauffage et à température élevées. Des expériences ont été réalisées dans un four à chute entre 800°C et 1400°C, à partir de particules de bois de taille 0,35 mm et 0,80 mm, dans une atmosphère inerte (100% molaire de N2), ou contenant de la vapeur d’eau (25% molaire). Les expériences ont également été simulées grâce à un modèle 1D avec des résultats positifs, ce qui a permis de mieux comprendre les phénomènes mis en jeu. Les solides obtenus (suies et char) ont été analysés et caractérisés. Des rendements élevés en gaz et goudrons, et un faible rendement en char ont été mesurés. Par conséquent, l'évolution de la phase volatile est déterminante pour les rendements des produits finaux. Au-dessus de 1000°C, la formation de suies devient importante. Les suies sont formées à partir de C2H2 et de HAP. En présence de vapeur d’eau, le rendement en suies est nettement moins élevé, ce qui s’explique essentiellement par le vaporeformage des précurseurs de suie, mais aussi par leur gazéification. La réaction de water-gas shift joue un rôle important dans la distribution des gaz majoritaires. La gazéification du char a été mise en évidence à 1200°C et 1400°C sous atmosphère humide. L'ensemble de ces réactions conduit à un gaz riche en H2, CO et CO2. L'équilibre thermodynamique est presque atteint à 1400°C avec une concentration de 25% molaire de H2O dans l’atmosphère. La graphitisation et la désactivation du char porté à haute température ont été mises en évidence expérimentalement. Néanmoins, ces phénomènes ont une influence négligeable sur l’évolution du rendement en char lors des expériences en four à chute. Enfin, la taille des particules n’a presque aucune influence sur les résultats expérimentaux. / Biomass gasification was studied in the conditions of an entrained flow reactor, namely at high heating rate and temperature. Experiments in a drop tube reactor were performed between 800°C and 1400°C, with wood particles of 0.35 mm and 0.80 mm size, under inert and steam containing - 25 mol% of H2O - atmospheres. These experiments were also simulated with a 1D model which gave good predictions. The collected solids, soot and char, were analyzed and characterized. This study highlights the importance of gas phase reactions on the yields of the final products, mainly gaseous compounds, in these conditions. These reactions are hydrocarbons cracking, reforming and polymerization, leading to soot formation, and water-gas shift. Char graphitization and deactivation were experimentally demonstrated. However, these phenomena have a negligible influence on char evolution in the drop tube reactor. Finally, the particle size was shown to have almost no influence on experimental results.

This thesis showcases a work that focused on developing processes with improved economic and environmental signatures. It illustrates the strengths of chemists and chemical engineers working together towards sustainable solutions. The joint collaboration between Drs. Liotta and Eckert allows the combination of disciplines to overcome economic and environment obstacles. This thesis depicts the application of chemical engineering and chemistry for industrial processes towards reducing cost and environmental impact. In chapter 2, a synthetic sequence yielding a pharmaceutical precursor was optimized for continuous processing. The precursor was for the pharmaceutical drug Ro 31-8959, which acts as a human immunodeficiency virus (HIV) protease inhibitor. A continuous flow reactor was designed, built and utilized successfully for the two-step reaction of the diazoketone pharmaceutical precursor, (1-benzyl-3-chloro-2-hydroxy-propyl)-carbamic acid tert-butyl ester. The best configuration for the continuous flow reactor involved a single and double coiled stainless steel reactor packed with glass beads. The yield obtained for the diazoketone was quantitative. In chapter 3, the cleavable surfactant (cleavable surfactants decompose in non-surface active ingredients upon stimulus), n-octyl thiirane oxide was synthesized, characterized and its surface activity and loss of surface activity upon heating was demonstrated. The n-octyl thiirane oxide surfactant activity was measured using a dye, Suddan III, and compared to a commercially available surfactant sodium dodecyl sulfate. In chapter 4, 5-amino-1H-tetrazole was synthesized using two novel synthetic routes starting from benign chemicals. Both routes involved Sharpless click chemistry in the first step to form the tetrazole ring. Both routes also used hydrogen transfer as the last step for the formation of the 5-amino-1H-tetrazole. These syntheses eliminated the use of highly toxic and/or explosive chemicals such as cyanamide, hydrazoic acid, and hydrazine. Finally in chapter 5, phase transfer catalysis was used as a means to improve reaction rates and yields between a siloxylated reagent (in the liquid phase) and insoluble ionic reagents (in the solid phase). The activity of commercial phase transfer catalysts like tetra-n-butylammonium bromide was compared to the activity of two novel custom-made siloxylated phase transfer catalysts. Surprisingly, the tetra-n-butylammonium resulted in superior rate constants to the custom made siloxylated phase transfer catalysts.

A frequency response tracer technique was used to study the hydraulic properties of a laboratory flow through reactor with variations in reactor size, flow rate and applied mixing. At any one set of conditions the reactor was studied over a range of input sine wave frequencies. Theoretical models consisting of in-series networks of completely mixed segments, plug flow segments, and dead space allowances were developed to approximate the experimental findings. / Thesis / Master of Engineering (ME)