Estudio de procesos de separación de hidrocarburos ligeros mediante el empleo de tamices moleculares
[EN] The aim of this thesis is to study the use of zeolites for the separation of light hydrocarbons. In order to do so, different zeolites were synthesized and characterized by different techniques to determine their crystallinity, composition and porosity. Then, adsorption measurements of various...
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| Tipo de recurso: | tesis doctoral |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | Universitat Politècnica de València (UPV) |
| Repositorio: | RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia |
| Idioma: | español |
| OAI Identifier: | oai:riunet.upv.es:10251/63244 |
| Acceso en línea: | https://riunet.upv.es/handle/10251/63244 |
| Access Level: | acceso abierto |
| Palabra clave: | Adsorción Zeolitas Separación Hidrocarburos ligeros Valorización de metano Isotermas Calor isostérico Cinéticas de adsorción |
| Sumario: | [EN] The aim of this thesis is to study the use of zeolites for the separation of light hydrocarbons. In order to do so, different zeolites were synthesized and characterized by different techniques to determine their crystallinity, composition and porosity. Then, adsorption measurements of various gases were carried out in order to determine both the adsorption capacity and the adsorption rate, as well as the isosteric heat of adsorption associated to these processes. Thus, the separation capacity of the zeolites for a given mixture of gases or vapors was evaluated. The main intention is to show how the development of new materials must be focused on the optimization of industrial chemical processes. Specifically, the scope of the materials studied during the thesis is related to the petrochemical industry. Given the nature of the zeolites, i.e. their high chemical and thermal strength, and their narrow pore size distribution in the molecular range, it is possible to use them for the separation of light hydrocarbons. First of all, thermodynamic and kinetic models given in the literature are presented, as well as the equations that calculate the isosteric heat of adsorption. Then, those models are compared in order to choose which provide with the best fitting of the experimental data. So, a methodology in the analysis of the results has been established during the development this work. The thesis is then focused on the separation of CO2 and CH4 for the upgrading of natural gas. In the first part, the effect of the zeolitic topology on the separation performance of both gases is studied, by using purely siliceous small pore zeolites. Next, the effect that the different polarity of the LTA zeolite, determined by the Si/Al ratio, might have on the adsorption capacity and selectivity to separate CO2 and CH4 is analyzed, establishing the optimum aluminum content that combines a good selectivity and high regenerability. Finally, zeolite Rho is used in the separation of both gases, because its pore size is in between the kinetic diameter of both molecules and have the Si/Al ratio close to the previously found optimal. So, it was obtained one of the zeolites with greater selectivity for CO2 and CH4 separation from those described in the open literature. In a third section, a new zeolite, named ITQ-50, obtained by solid state transformation from another zeolite under conditions of ultrahigh pressure, being the first case reported in the literature is presented. The results of adsorption of various gases in zeolite ITQ-50 are also shown. On the one hand, the adsorption of CO2 and CH4 was studied in order to evaluate the capability to separate both gases. On the other hand, the most relevant data from isotherms and kinetic measurements of short chain hydrocarbons (C3-C4) are discussed, focusing the study on the separation of alkanes and alkenes. Finally, the influence of the presence of high germanium content in the zeolitic framework of ITQ-29 on the diffusion of light hydrocarbons, in particular propane and propene, is studied. This is one of the most significant separation processes in the refining and petrochemical industry. |
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