Preparation and characterization of mixed matrix membranes for gas separation and pervaporation
- Autores: Roberto Castro Muñoz
- Directores de la Tesis: Vlastimil Fila (dir. tes.), Joaquín Coronas Ceresuela (dir. tes.), Enrico Drioli (dir. tes.)
- Lectura: En la Universidad de Zaragoza ( España ) en 2019
- Idioma: español
- Tribunal Calificador de la Tesis: Karel Bouzek (presid.), Zaneta Dohnalova (secret.), Jan Hives (voc.)
- Programa de doctorado: Programa de Doctorado en Ingeniería Química y del Medio Ambiente por la Universidad de Zaragoza
- Materias:
- Enlaces
- Tesis en acceso abierto en: Zaguán
- Resumen
The main aim of this research work was to develop mixed matrix membranes (MMMs), which may provide superior performance compared to the base pristine polymers, for two different types of membrane-based technologies (e.g. gas separation and pervaporation). In the first part of the thesis, the enhancement of CO2 permeation of a commercial polymer, like Matrimid®5218 polyimide, was aimed. At this point, it is proposed, for the first time, the preparation of ternary MMMs based on the filling ZIF-8 nanoparticles (33.83 ± 6.2 nm) into Matrimid®-PEG 200 blend. The MMMs membranes were tested at fixed feed composition (50:50) and different feed pressures (from 2 to 8 bar). The MMMs were also characterized using SEM, EDX, DSC, and TGA. The results indicate that the incorporation of 30 wt.% of ZIF-8 nanoparticles leads to increase of CO2 permeability in binary (up to 31.47 Barrer) and ternary MMMs (up to 33.12 Barrer); pointing out that the addition of PEG and ZIF-8 enhanced the CO2 permeability (more than 3-folds) comparing to the neat Matrimid® membranes (7.16 Barrer).
The use of this commercial Matrimid®5218 polyimide, as a hydrophilic polymer, has been also extended to other membrane technology (e.g. pervaporation). The potentiality of this polyimide deals with the separation of organic-organic azeotropic mixtures. Herein, Matrimid® membranes were prepared and tested, for the first time, in pervaporation (PV) separation of azeotropic methanol (MeOH)- methyl tert-butyl ether (MTBE) mixture (14.3 and 85.7%, respectively). The PV experiments were carried out at different feed temperatures (25-45ºC) and vacuum pressures (0.0538, 0.2400, 2.1000 mbar) at permeate side. The results pointed out that the feed temperature (in the range of 25-45 ºC) affected mainly the MeOH permeation producing an increasing on its partial permeate flux and separation factor as well. Importantly, the best performances of Matrimid® were found at 45 ºC and 0.054 mbar, where a permeate flux and a separation factor of about 0.073 kg m-2 h-1 and 21.16, respectively, were reached.
In the last part of this thesis, the enhancement of another commercial polymer, like poly(vinyl alcohol) (PVA), was proposed for PV applications. In this way, a highly hydrophilic inorganic material, like graphene oxide (GO), was successfully prepared and incorporated into a cross-linked PVA matrix. The MMMs were tested for the dehydration of ethanol (10:90 wt. % water-ethanol), monitoring their performance in terms of total permeate flux, components fluxes, as well as their separation factor. The effect of filler was analyzed by doubling the GO content (at 0.5, 1.0, and 2.0 wt.%) in the MMMs. Furthermore, the membranes were characterized by FESEM, DSC, TGA, XRD, and measurements of degree of swelling, water contact angle, and mechanical properties. The best performance of such MMMs (containing 1 wt.% of GO) was found at 40 ºC, displaying a separation factor of 263 and a permeate flux of about 0.137 kg·m-2·h-1 (in which 0.133 kg·m-2·h-1 corresponds to water). This result represents a 75 % enhancement of the original permeation rate of pristine cross-linked PVA membranes.
Finally, this work reports the enhancement of two commercial polymers (such as Matrimid®5218 polyimide and poly(vinyl alcohol) (PVA)). It is important to mention that such polymers were chosen according to their consolidation in large-scale production and their near application at industrial scale. In general, the chapters also address the literature reviews to select each case of study, and thus to be attended during this research (e.g. CO2/CH4 and MeOH-MTBE separations as well as ethanol dehydration). Moreover, this thesis provides relevant insights into the suitable preparation procedures to reach high performing MMMs
