Due to environmental challenges, depleting oil resources, rising cost of oil and instability in oil-producing countries, biofuel production has attracted a lot of attention in recent decades. Biobutanol is one of the biofuels showing the most potential as an alternative for partly replacing petroleum-based fuels. Both researchers and industrialists are currently working at developing an energy-effective process to produce biobutanol at a large scale. Acetone-butanol-ethanol (ABE) fermentation is the biological process of biobutanol production and Clostridia are the most common bacteria used to produce biobutanol. However, there are several challenges in the butanol bioproduction process that should be addressed to make this process economically viable. The main challenge in the biobutanol production process is the low concentration of butanol in the ABE fermentation broth. It is therefore important to develop an efficient separation method. Several separation methods such as distillation, liquid-liquid extraction (LLE), pervaporation, gas stripping and adsorption have been considered to recover butanol from dilute solutions and ABE fermentation broths. Adsorption is considered as one of the most promising methods due to its high performance and energy efficiency for butanol separation. In this study, the focus was on developing an efficient separation method for butanol recovery from dilute model solution and fermentation broth using adsorption. A comprehensive adsorbent screening was first carried out to identify the best commercially available adsorbent among a series of potentially promising adsorbents. Activated carbon (AC) F-400 was selected for further experimentation since it showed high adsorption capacity and adsorption rate in addition to high selectivity toward butanol. AC F-400 was then tested extensively in packed adsorption column experiments for binary and ABE model solutions and fermentation broths to investigate the competitive adsorption between butanol and other components present in ABE broths. The results showed that the butanol adsorption capacity was not affected by the presence of ethanol, glucose and xylose while the presence of acetone led to a slight decrease in adsorption capacity at low butanol concentrations. On the other hand, the presence of acids (acetic acid and butyric acid) in the ABE broth showed a significant effect on the butanol adsorption capacity over a wide ii range of butanol concentration and this effect was more pronounced for butyric acid. At the end, different competitive adsorption isotherm models were also studied to appropriately represent the behaviour of the competitive adsorption. Desorption of butanol was subsequently investigated to evaluate both the desorption capacity of butanol and the capability of the adsorbent particles to be used for multiple adsorption-desorption cycles. The results of this set of experiments showed that AC F-400 can retain its initial adsorption capacity after 6 adsorption/desorption cycles. The recovery of butanol from butanol-water (1.5 wt%) binary and ABE model solutions was 84 and 80% with butanol adsorption capacity of 302 and 171 mg/g, respectively. The combination of adsorption and gas stripping techniques was also studied to investigate the performance of CO2 gas stripping of solvents from the model solutions and fermentation broths followed by adsorption. The results showed that the butanol adsorption capacity of the overall system for binary solutions (260 mg/g for a binary butanol-water solution of 15 g/L with vapour phase concentration of 5.8 mg/L), ABE model solutions (192 mg/g for a corresponding vapour concentration of 5.2 mg/L) and ABE fermentation broths (247 mg/g for a corresponding vapour phase concentration of 2.5 mg/L) was higher than what has been published in the literature. Finally, a model was developed and adequately validated the experimental data to predict the behaviour of the ABE compounds in a packed bed adsorption column for butanol separation from dilute solutions.

The use of biofuels as an alternative to gasoline in the transportation sector is seen by policy makers as an important strategy to reduce global greenhouse gas emissions. Biobutanol is one such biofuel that is gathering increasing attention in the biofuel community, because of its preferable fuel qualities over bioethanol. However, despite increasing research into biobutanol production, the thermochemical route for biobutanol production has not been adequately studied in the peer-reviewed literature. In light of this motivation, this thesis considers the design, and economic and environmental assessment of thermochemical plants for producing second and third generation biobutanol. In addition, the potential for using process intensification technology such as dividing wall columns (DWC) in place of conventional distillation columns is also investigated as a way to improve thermochemical biobutanol plants. As a first step, a novel thermochemical plant for producing second generation biobutanol is developed. Detailed economic analysis of this plant show that it is competitive with gasoline under certain process, and market conditions. The designed plant is then extended, with some modifications, to evaluate the economic and environmental potential of a thermochemical plant for producing third generation biobutanol from macroalgae. It was concluded from the results that the thermochemical route is preferable for producing second generation biobutanol over third generation biobutanol. The novel thermochemical plant design is then updated by using a kinetic model of a pilot-scale demonstrated catalyst to represent the critical mixed alcohol synthesis reaction step. This change allows optimal unreacted syngas recycle configurations for maximizing butanol yield to be established. Furthermore, integrating a DWC, designed using a methodology developed in the thesis, into the updated thermochemical plant leads to additional plant improvements. Overall, the work carried out in this thesis demonstrates that the thermochemical route is a viable option for producing second generation biobutanol. / Thesis / Doctor of Philosophy (PhD)

[ES] En esta tesis se han estudiado las propiedades de diferentes adsorbentes zeolíticos y su uso en separaciones de mezclas fluidas de interés industrial. La selección de los materiales se ha realizado poniendo especial énfasis en los adsorbentes zeolíticos de poro pequeño de baja polaridad, más concretamente, zeolitas pura sílice, aluminofosfatos y silicoaluminofosfatos. Las separaciones que se han considerado están relacionadas principalmente con la producción de energía, procesado del gas natural y del biogás, purificación de hidrógeno, mejora del índice de octano de la gasolina y purificación de biobutanol. Las propiedades de adsorción se han estudiado mediante medidas de isotermas de adsorción de un solo componente, medidas de cinéticas de adsorción de un solo componente y experimentos de adsorción dinámica multicomponente, es decir, experimentos de curvas de ruptura. Las isotermas de adsorción se analizaron en cuanto a forma y capacidad máxima de adsorción y se utilizaron para calcular los calores isostéricos de adsorción, las selectividades termodinámicas y las capacidades de trabajo ideales en procesos hipotéticos de adsorción por oscilación. Las medidas de cinéticas de adsorción han permitido comparar el comportamiento difusional de diferentes adsorbatos en diferentes materiales y calcular las constantes de difusión temporales, que a su vez fueron utilizadas para calcular selectividades cinéticas ideales / factores de separación. Los experimentos de curvas de ruptura se utilizaron para ver cómo se comportan los materiales en condiciones cercanas al caso industrial, para calcular las selectividades reales de mezcla y los parámetros de operación relevantes de procesos de adsorción, es decir, productividad, recuperación y pureza. Las propiedades físicas de los materiales estudiados, como la estructura, el orden cristalino, la conectividad atómica, el tamaño y la forma de las partículas y las propiedades texturales, han sido evaluadas y empleadas para explicar los resultados obtenidos en los experimentos de adsorción. En el capítulo 1, se presenta una introducción general sobre las zeolitas, su síntesis, propiedades y aplicaciones, junto con una introducción acerca de los fenómenos de adsorción y las separaciones industriales de interés para esta tesis. En el capítulo 2 se presentan los objetivos de este trabajo de tesis. En el capítulo 3 se presenta la síntesis de los adsorbentes utilizados, junto con los equipos de caracterización y adsorción y los procedimientos de análisis de datos de adsorción. En el capítulo 4, se estudia la adsorción de gases ligeros en Si-RWR con especial énfasis en la separación de isótopos de hidrógeno y la purificación del hidrógeno presente en la corriente de salida de un proceso de reformado de metano con vapor. En el capítulo 5 estudio las propiedades de adsorción de \ce{CO2} en aluminofosfatos, silicoaluminofosfatos y zeolitas de estructuras LTA, CHA y AFI, y más específicamente los calores isostéricos de adsorción. En el capítulo 6, estudio el efecto del tamaño de poro y la topología de poro en la separación de \ce{CO2} de \ce{CH4} mediante isotermas de compuestos puros y experimentos de ruptura de la mezcla. En el capítulo 7, se estudian las propiedades de adsorción de hidrocarburos de las fracciones C5-C7 en Si-STW con la atención puesta en la separación de hidrocarburos dirramificados de monorramificados y lineales. Se establece una comparación con Si-MFI. En el capítulo 8 se estudia una serie de zeolitas puramente silíceas para la separación de una mezcla de vapores de 1-butanol, acetona, etanol y agua proveniente de un proceso de fermentación. Se han realizado experimentos de adsorción de los compuestos puros, así como de mezclas de ellos mediante curvas de ruptura. Se presta atención a la recuperación de 1-butanol durante el proceso de adsorción, estudiá / [CA] En aquesta tesi, s'han estudiat les propietats de diferents adsorbents zeolítics i el seu ús en separacions de mescles de fluids d'interès industrial. La selecció dels materials s'ha dut a terme posant un èmfasi especial en els adsorbents zeolítics de porus petit de baixa polaritat, més concretament, les zeolites pura sílice, aluminofosfats i silicoaluminofosfats. Les separacions que s'han considerat estan relacionades principalment amb la producció d'energia, el processament de gas natural i de biogàs, la purificació d'hidrogen, la millora del nombre d'octans de la gasolina i la purificació de biobutanol. Les propietats d'adsorció s'han estudiat mitjançant isotermes d'adsorció d'un component, cinètiques d'adsorció d'un component i experiments d'adsorció dinàmica multicomponent, és a dir, experiments de corbes de ruptura. Les isotermes d'adsorció es van analitzar en funció de la seva forma i capacitat màxima d'adsorció i es van utilitzar per calcular les calors isostèriques d'adsorció, les selectivitats termodinàmiques i les capacitats de treball ideals en els hipotètics processos d'adsorció per oscil·lació . Les mesures de cinètiques d'adsorció han permès comparar el comportament difusional de diferents adsorbats en diferents materials i calcular constants temporals de difusió, que, al seu torn, s'han utilitzat per al càlcul de selectivitats cinètiques ideals/factors de separació. Els experiments de corbes de ruptura es van utilitzar per, veure com funcionen els materials en condicions properes al cas industrial i per calcular per a cada mescla les selectivitats i els paràmetres d'operació rellevants per a processos d'adsorció, és a dir, la productivitat, la recuperació i la puresa. Les propietats físiques dels materials estudiats, com ara l'estructura, l'ordre cristal·lí, la connectivitat dels àtoms, la mida i la forma de les partícules i les propietats texturals s'han avaluat i s'han utilitzat per explicar els resultats obtinguts en els experiments d'adsorció. En el capítol 1, es proporciona una introducció general sobre les zeolites, la seva síntesi, propietats i aplicacions, juntament amb una introducció referent a fenòmens d'adsorció i separacions industrials d'interès en aquesta tesi. En el capítol 2 es presenten els objectius d'aquest treball de tesi. En el capítol 3 es presenta la síntesi dels adsorbents utilitzats, juntament amb els equips de caracterització i adsorció i els procediments d'anàlisi de dades d'adsorció. En el capítol 4, s'estudia l'adsorció de gasos lleugers a Si-RWR amb especial atenció a la separació d'isòtops d'hidrogen i la purificació de l'hidrogen present en el corrent de sortida d'un procés de reformat de metà amb vapor. En el capítol 5 estudio les propietats d'adsorció de \ce{CO2} en aluminofosfats, silicoaluminofosfats i zeolites d'estructures LTA, CHA i AFI i, més concretament, les seus calors d'adsorció isostèriques. En el capítol 6, estudio l'efecte de la mida i la topologia de porus sobre la separació de \ce{CO2} de \ce{CH4} mitjançant isotermes de components purs i experiments de ruptura de la mescla. En el capítol 7, s'estudien les propietats d'adsorció d'hidrocarburs de les fraccions C5-C7 en Si-STW amb especial atenció a la separació d'hidrocarburs lineals i monorramificats de dirramificats. S'estableix una comparació amb Si-MFI. En el capítol 8 s'estudia una sèrie de zeolites purament silícies per a la separació d'una mescla de vapors de 1-butanol, acetona, etanol i aigua provinent d'un procés de fermentació. S'han realitzat experiments d'adsorció dels compostos purs, així com de mescles d'ells mitjançant corbes de ruptura. Es para atenció a la recuperació de 1-butanol durant el procés d'adsorció, estudiant-se la recuperació del producte desitjat enfront de la puresa d'aquest. / [EN] In this thesis, the properties of different zeolitic adsorbents and their use in separations of fluid mixtures of industrial interest have been studied. The selection of the materials has been carried out putting a special emphasis on low polarity small pore zeolitic adsorbents, more specifically, pure silica zeolites, aluminophosphates and silicoaluminophosphates. The separations that have been considered are related mostly to energy production, natural and biogas upgrading, purification of hydrogen, gasoline octane number improvement and purification of biobutanol. The adsorption properties of the zeolitic materials have been studied by single component adsorption isotherm measurements, single component adsorption kinetics measurements and multicomponent dynamic adsorption experiments, i.e. breakthrough experiments. The adsorption isotherms were analysed in terms of their shape, the maximum adsorption capacity and used to calculate isosteric heats of adsorption, ideal thermodynamic selectivities and ideal working capacities in hypothetical swing adsorption processes. The adsorption kinetics measurements have allowed to compare the diffusional behavior of different adsorbates in different materials and to calculate diffusional time constants, which were, in turn, used for calculating ideal kinetic selectivities/separation factors. The breakthrough experiments were used to ultimately see how materials perform at conditions close to the industrial case and to calculate for each material mixture selectivities and relevant swing adsorption process operation parameters, i.e. productivity, recovery and purity. The physical properties of the studied materials, such as structure, crystalline order, atom connectivity, particle size and shape and textural properties have been critically evaluated and used to explain the results obtained in the adsorption studies. In chapter 1, a general introduction on zeolites, their synthesis, properties and applications is provided, together with an introduction on adsorption phenomena and on the industrial separations of interest to this thesis. In chapter 2 the objectives of this thesis work are presented. In chapter 3 the synthesis of the adsorbents used is presented, together with the characterization and adsorption equipment and the adsorption data analysis procedures. In chapter 4, the adsorption of light gases on pure silica RWR zeolite is studied with special focus on the separation of hydrogen isotopes and the purification of hydrogen from steam methane reformery off-gas. In chapter 5 I study the adsorption properties of CO2 on aluminophosphates, silicoaluminophosphates and zeolites of LTA, CHA and AFI structures, and more specifically their isosteric heats of adsorption. In chapter 6, I study the effect of pore size and pore topology on the separation of CO2 from CH4 by means of pure component isotherms and breakthrough experiments of the mixture. In chapter 7, the adsorption properties of C5-C7 hydrocarbons on pure silica STW zeolite are studied with special focus on the separation of dibranched from monobranched and linear hydrocarbons. A comparison with pure silica MFI zeolite (silicalite-1) is established. In chapter 8 a set of pure silica zeolites is studied as adsorbents for the vapor phase separation of 1-butanol from acetone, ethanol and water, typical components of the ABE fermentation broth. Pure component isotherms were measured and breakthrough experiments were carried out using multicomponent mixtures. Special focus is put on the recovery of 1-butanol from the desorption curve, and the dependence of purity with recovery is studied. / I would like to thank the Spanish Ministry of Science, Innovation and Universities (MCIU) for my grant FPU15/01602, which has allowed me to carry out this thesis. I thank again the MCIU for paying my short stay in Brussels and for the funding provided through many different projects (RTI2018-101784-B-I00, Program Severo Ochoa SEV-2016-0683; and previous ones), which covered the costs of my research activities and allowed for my assistance to numerous international conferences which completed my training as a scientist. I thank the Instituto de Tecnología Química, the Universitat Politècnica de València (UPV) and the Consejo Superior de Investigaciones Científicas for providing the infrastructure needed for carrying out successful research. / Pérez Botella, E. (2021). Porous Solids for Adsorption and Separation of Gas and Vapor Mixtures [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/178978

The subject of this thesis are both available and potentional gaseous and liquid biofuels. The thesis deals with their detailed description and comparison. The first part describes the current legislation and the basic types of biofuels. The main part focuses then on biofuels themselves, their characteristics, production, utilization, and their impact on environment. In further parts, emissions created during the cycle of production and distribution of biofuel are characterized. Last part brings comparison of biofuels from different points of view, and recommendation of the alternative ways of production of gaseous and liquid biofuels from renewable resources of energy.