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Producción Científica, In this work, CO2 adsorption at 273.15 K and N2 adsorption at 77 K of mixed matrix membranes has been studied, as a method to directly determine their fractional free volume (FFV). These membranes consist of a continuous phase of copoly(o-hydroxyamide)s (HPA) or copoly(o-hydroxyamide-amide)s (PAA) and a relatively highly porous polymer network filler (PPN1). Both the pure copolymers and the mixed matrix membranes (MMMs) have been analyzed before and after a thermal rearrangement (TR) process. The CO2 adsorption results have allowed characterizing the pore size distribution of the studied membranes in the 3–15 Å range, by using the Non-Local Density Functional Theory (NLDFT). Whereas the N2 adsorption has allowed determining the pore size distributions in the range between 20 and 250 Å. The experimental determination of the pore volume and the density allows the direct calculation of the membranes’ free volume fractions, which were in good agreement with the most usual FFV evaluation methods. In addition, part of the pore volume detected by N2 adsorption was associated with defects and poor integration of the membrane components. This correction has allowed us to make a new evaluation of the density of these materials., Gobierno de España (AEI) proyects (PID2019-109403RB-C21/AEI/10.13039/501100011033 y PID2019-109403RB-C22/AEI/10.13039/501100011033), Junta de Castilla y León - EU-FEDER (CL-EI-2021-07, UIC082)

Producción Científica, Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación/10.13039/501100011033 y Fondo Europeo de Desarrollo Regional (FEDER) - (projects PID2019- 109403RBC21, PID2019-109403RBC22 y EQC2019-006481-P), Junta de Castilla y León y Fondo Europeo de Desarrollo Regional (FEDER) - (grant CLU2017-09, UIC082, VA088G19), Universidad de Valladolid - (PROYEMER-2021-05)

Producción Científica, Biogas and biohydrogen, due to their renewable nature and zero carbon footprint, are considered two of the gaseous biofuels that will replace conventional fossil fuels. Biogas from anaerobic digestion must be purified and converted into high-quality biomethane prior to use as a vehicle fuel or injection into natural gas networks. Likewise, the enrichment of biohydrogen from dark fermentation requires the removal of CO2, which is the main pollutant of this new gaseous biofuel. Currently, the removal of CO2 from both biogas and biohydrogen is carried out by means of physical/chemical technologies, which exhibit high operating costs and corrosion problems. Biological technologies for CO2 removal from biogas, such as photosynthetic enrichment and hydrogenotrophic enrichment, are still in an experimental development phase. In this context, membrane separation has emerged as the only physical/chemical technology with the potential to improve the performance of CO2 separation from both biogas and biohydrogen, and to reduce investment and operating costs, as a result of the recent advances in the field of nanotechnology and materials science. This review will focus on the fundamentals, potential and limitations of CO2 and H2 membrane separation technologies. The latest advances on membrane materials for biogas and biohydrogen purification will be systematically reviewed., Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación (AEI)/10.13039/501100011033 - (projects PID2019- 109403RB-C21), Junta de Castilla y León y Fondo Europeo de Desarrollo Regional (FEDER) - (grant CLU2017-09, UIC082, CL-EI-2021-07 and UIC 315)

Producción Científica, Copoly(o-hydroxyamide)s (HPA) and copoly(o-hydroxyamide-amide)s (PAA) have been synthesized to be used as continuous phases in mixed matrix membranes (MMMs). These polymeric matrices were blended with different loads (15 and 30 wt.%) of a relatively highly microporous porous polymer network (PPN). SEM images of the manufactured MMMs exhibited good compatibility between the two phases for all the membranes studied, and their mechanical properties have been shown to be good enough even after thermal treatment. The WAX results show that the addition of PPN as a filler up to 30% does not substantially change the intersegmental distance and the polymer packing. It seems that, for all the membranes studied, the free volume that determines gas transport is in the high end of the possible range. This means that gas flow occurs mainly between the microvoids in the polymer matrix around the filler. In general, both HPA- and PAA-based MMMs exhibited a notable improvement in gas permeability, due to the presence of PPN, for all gases tested, with an almost constant selectivity. In summary, although the thermal stability of the PAA is limited by the thermal stability of the polyamide side chain, their mechanical properties were better. The permeability was higher for the PAA membranes before their thermal rearrangement, and these values increased after the addition of moderate amounts of PPN., Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación (AEI)/10.13039/501100011033 - (projects PID2019- 109403RB-C21 and PID2019-109403RB-C22), Junta de Castilla y León y Fondo Europeo de Desarrollo Regional (FEDER) - (grant CLU2017-09, CL-EI-2021-07, UIC082)

Producción Científica, A set of thermally rearranged mixed matrix membranes (TR-MMMs) was manufactured and tested for gas separation. These membranes were obtained through the thermal treatment of a precursor MMM with a microporous polymer network and an o-hydroxypolyamide,(HPA) created through a reaction of 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (APAF) and 5′-terbutil-m-terfenilo-3,3″-dicarboxylic acid dichloride (tBTmCl). This HPA was blended with different percentages of a porous polymer network (PPN) filler, which produced gas separation MMMs with enhanced gas permeability but with decreased selectivity. The thermal treatment of these MMMs gave membranes with excellent gas separation properties that did not show the selectivity decreasing trend. It was observed that the use of the PPN load brought about a small decrease in the initial mass losses, which were lower for increasing PPN loads. Regarding the glass transition temperature, it was observed that the use of the filler translated to a slightly lower Tg value. When these MMMs and TR-MMMs were compared with the analogous materials created from the isomeric 5′-terbutil-m-terfenilo-4,4″-dicarboxylic acid dichloride (tBTpCl), the permeability was lower for that of tBTmCl, compared with the one from tBTpCl, although selectivity was quite similar. This fact could be attributed to a lower rigidity as roughly confirmed by the segmental length of the polymer chain as studied by WAXS. A model for FFV calculation was proposed and its predictions compared with those evaluated from density measurements assuming a matrix-filler interaction or ideal independence. It turns out that permeability as a function of FFV for TR-MMMs follows an interaction trend, while those not thermally treated follow the non-interaction trend until relatively high PPN loads were reached., Ministerio de Ciencia e Innovación, Agencia Estatal de Investigación - (projects PID2019- 109403RB-C21/AEI/10.13039/501100011033 and PID2019-109403RB-C22/AEI/10.13039/501100011033), Junta de Castilla y León, Unión Europea y Fondo Europeo de Desarrollo Regional (FEDER) - (project CLU2017-09, UIC082)

Producción Científica, Gobierno de España - (Projects PID2019- 109403RBC21/AEI/10.13039/501100011033, PID2019-109403RBC22/AEI/10.13039/501100011033 and EQC2019-006481-P), Junta de Castilla y León y Fondo Europeo de Desarrollo Regional (FEDER) - (Projects CLU2017-09, UIC082, VA088G19)

En este trabajo se prepararon membranas de matriz mixta (MMMs) cargadas con una red polimérica porosa (PPN por sus siglas en inglés) de 1,3,5-trifenilbenceno-trifluoroacetofenona (1,3,5- TPB- TFAP) sobre una poliimida aromática comercial, Matrimid®, con el fin de estudiar el rendimiento y las prestaciones en la separación de gases. El PPN es una red altamente microporosa que tiene una elevada absorción de CO2 y una alta estabilidad química y térmica. Fue caracterizado, además, por microscopía electrónica de barrido (SEM) y el estudio de la isoterma de adsorción-desorción de N2 mediante el análisis de superficie multipunto Brunauer-Emmett-Teller (BET). Las membranas obtenidas se caracterizaron por SEM, difracción de rayos X (XRD), espectroscopía de infrarrojos por transformada de Fourier (FT-IR), análisis termogravimétrico (TGA), calorimetría diferencial de barrido (DSC) y propiedades mecánicas mediante curvas esfuerzo-deformación. La adecuada compatibilidad y adhesión entre los componentes (contenido de PPN de 15 y 30% p/p) fue respaldada por el ligero aumento de la temperatura de transición vítrea de las MMM con respecto a la membrana de poliimida pura. Se observó además una distribución uniforme de partículas de PPN en la matriz. Las propiedades mecánicas de las membranas son suficientemente buenas para ser probadas y estudiadas en la separación de gases. Las propiedades de transporte de gas de las membranas para gases puros He, N2, O2, CO2 y CH4 se midieron a 30 °C y a una presión de alimentación de 3 bar utilizando un permeador de gases de volumen constante/presión variable. La adición de las partículas de PPN mejoraron las propiedades de permeación de las membranas en todos los gases probados, aumentando además la difusividad. Las mejoras de las propiedades permoselectivas fueron especialmente destacables en el CO2, incrementando un 111 % y un 180 % para membranas cargadas con el 15 y 30% de PPN respectivamente, en comparación con la poliimida pura. También se, Departamento de Física Aplicada, Máster en Física

Producción Científica, A hydroxypolyamide (HPA) manufactured from 2,2-bis(3-amino-4-hydroxy phenyl)-hexafluoropropane (APAF) diamine and 5′-terbutyl-m-terphenyl-4,4′′-dicarboxylic acid chloride (tBTpCl), and a copolyimide produced by stochiometric copolymerization of APAF and 4,4′-(hexafluoroisopropylidene) diamine (6FpDA), using the same diacid chloride, were obtained and used as polymeric matrixes in mixed matrix membranes (MMMs) loaded with 20% (w/w) of two porous polymer networks (triptycene-isatin, PPN-1, and triptycene-trifluoroacetophenone, PPN-2). These MMMs, and also the thermally rearranged membranes (TR-MMMs) that underwent a thermal treatment process to convert the o-hydroxypolyamide moieties to polybenzoxazole ones, were characterized, and their gas separation properties evaluated for H2, N2, O2, CH4, and CO2. Both TR process and the addition of PPN increased permeability with minor decreases in selectivity for all gases tested. Excellent results were obtained, in terms of the permeability versus selectivity compromise, for H2/CH4 and H2/N2 separations with membranes approaching the 2008 Robeson’s trade-off line. The best gas separation properties were obtained when PPN-2 was used. Finally, gas permeation was characterized in terms of chain intersegmental distance and fraction of free volume of the membrane along with the kinetic diameters of the permeated gases. The intersegmental distance increased after TR and/or the addition of PPN-2. Permeability followed an exponential dependence with free volume and a quadratic function of the kinetic diameter of the gas., Agencia Estatal de Investigación (projects PID2019-109403RB-C21 and PID2019-109403RB-C22), Junta de Castilla y León - Fondo Europeo de Desarrollo Regional (projects CLU2017-09, UIC082 and VA088G19)

Biogas and biohydrogen, due to their renewable nature and zero carbon footprint, are considered two of the gaseous biofuels that will replace conventional fossil fuels. Biogas from anaerobic digestion must be purified and converted into high-quality biomethane prior to use as a vehicle fuel or injection into natural gas networks. Likewise, the enrichment of biohydrogen from dark fermentation requires the removal of CO2, which is the main pollutant of this new gaseous biofuel. Currently, the removal of CO2 from both biogas and biohydrogen is carried out by means of physical/chemical technologies, which exhibit high operating costs and corrosion problems. Biological technologies for CO2 removal from biogas, such as photosynthetic enrichment and hydrogenotrophic enrichment, are still in an experimental development phase. In this context, membrane separation has emerged as the only physical/chemical technology with the potential to improve the performance of CO2 separation from both biogas and biohydrogen, and to reduce investment and operating costs, as a result of the recent advances in the field of nanotechnology and materials science. This thesis will focus on the fundamentals, potential and limitations of CO2 and H2 membrane separation technologies. The latest advances on membrane materials for biogas and biohydrogen purification will be systematically reviewed. In this thesis work, it was shown that, as in the case of Mixes Matrix Membranes (MMM), subtle changes in polymer chemistry as well as fillers can have important effects on the polymer-filler interactions and properties of TR-MMMs, both before and after thermal rearrangement. It was further demonstrated that advanced nanoporous materials currently being explored as fillers in MMMs can also be applied to improve the gas separation performance of polymers suitable for producing benzoxazoles, following the same strategy in MMMs., El biogás y el biohidrógeno, por su carácter renovable y su nula huella de carbono, se consideran dos de los biocombustibles gaseosos que sustituirán a los combustibles fósiles convencionales. El biogás procedente de la digestión anaeróbica debe purificarse y convertirse en biometano de alta calidad antes de su uso como combustible para vehículos o su inyección en las redes de gas natural. Asimismo, el enriquecimiento del biohidrógeno procedente de la fermentación oscura requiere la eliminación del CO2, que es el principal contaminante de este nuevo biocombustible gaseoso. En la actualidad, la eliminación del CO2 tanto del biogás como del biohidrógeno se lleva a cabo mediante tecnologías físico-químicas, que presentan elevados costes de funcionamiento y problemas de corrosión. Las tecnologías biológicas para la eliminación del CO2 del biogás, como el enriquecimiento fotosintético y el enriquecimiento hidrogenotrófico, están todavía en fase de desarrollo experimental. En este contexto, la separación por membranas ha surgido como la única tecnología físico-química con potencial para mejorar el rendimiento de la separación de CO2 tanto del biogás como del biohidrógeno, y para reducir los costes de inversión y de explotación, como resultado de los recientes avances en el campo de la nanotecnología y la ciencia de los materiales. Esta tesis se centra en los fundamentos, el potencial y las limitaciones de las tecnologías de separación por membranas de H2 y CO2. Se revisaron sistemáticamente los últimos avances en materiales de membrana para la purificación de biogás y biohidrógeno. En este trabajo de tesis, se demostró que, como en el caso de las membranas de matriz mixta (MMM), los cambios sutiles en la química de los polímeros, así como en los rellenos, pueden tener efectos importantes en las interacciones polímero-relleno y en las propiedades de las TR-MMM, tanto antes como después del reordenamiento térmico. Además, se demostró que los materiales nanoporosos avanzados, Escuela de Doctorado, Doctorado en Ingeniería Química y Ambiental