Template-controlled acidity and catalytic activity of ferrierite crystals

A synthesis strategy to tailor the acid sites location in ferrierite crystals has been developed. The zeolite catalysts were synthesised in fluoride medium using different combinations of organic structure directing agents (SDAs) in the absence of inorganic cations. Therefore, the negative charge associated to the incorporation of aluminium to the framework was compensated exclusively by the positive charge of the organic SDAs. In this way, Al sitting in the zeolite framework was driven by the specific location of the different SDA molecules within the zeolite void volume. Following this synthesis strategy, it has been found that the distribution of strongly acidic hydroxyl groups in the proton form of the zeolites obtained after removal of the organic templates was dependent on the combination of organic molecules used as SDAs. Moreover, the catalytic activity of the zeolites in m-xylene and 1-butene isomerisation increased as the relative population of strong Brönsted acid groups in sterically constrained sites inside the ferrierite cavity decreased.This work has been financially supported by the MICINN (project CTQ2006-06282).Peer reviewe

Influence of Al distribution and defects concentration of ferrierite catalysts synthesized from Na-free gels in the skeletal isomerization of n-butene

The skeletal isomerization of n-butenes to isobutene has been carried out over ferrierite catalysts (Si/Al ~ 15) containing different acid sites distribution and different amount of defects. The zeolite crystals were synthesized under hydrothermal conditions in fluoride medium in the absence of alkaline cations by using suitable combinations of structure directing agents. Template-driven low density of acid sites in 10-membered-ring channels enhances the isobutene selectivity and decreases catalyst deactivation. The presence of high amount of silanol groups and Lewis acid sites increases the yields of by-products and catalysts decay.MICINN (CTQ2006-06282) CSIC (JAE-doc contract)Peer reviewe

Tailoring the acid strength of microporous silicoaluminophosphates through the use of mixtures of templates: Control of the silicon incorporation mechanism

SAPO-5 samples have been synthesized with triethylamine (TEA), benzylpyrrolidine (BP) and mixtures of them as structure directing agents (SDAs). It has been observed that in the as-synthesised materials the concentration of SDAs (molecules per unit cell) and the Si content are similar. According to the different molecular size of both SDAs, the samples exhibit higher organic weight and lower water content as the molar fraction of BP in the synthesis gel increases. These differences in selectivity for organic/water incorporation influences the mechanism of Si substitution in the AlPO lattice: the higher organic content obtained at higher BP/TEA ratio leads to the formation of large Si islands, while the higher water content of the sample obtained with TEA enhances the formation of isolated Si(OAl)4 environments. Interestingly, it has been found that these two opposite trends can be tailored to a certain point by using mixtures of both SDAs, TEA and BP, in the required ratio. The catalytic activity of the samples has been tested in the isomerisation of m-xylene. It has been observed a higher activity of samples obtained with BP as the main SDA, thus evidencing the better performance of large Si islands in this reaction.MEC (CTQ2006-06282)Peer reviewe

Informe sobre la situación actual de los titulados superiores y técnicos especialistas de grado medio de los OPIs adscritos al Consejo Superior de Investigaciones Científicas

28 páginas. Este informe no se encuentra clasificado en ninguna colección. Se presentó ante el Secretario de Estado de Universidades e Investigación del Ministerio de Educación y Ciencia y ante el Presidente del C.S.I.C. El grupo de trabajo que ha elaborado el presente documento está formado, en su totalidad, por funcionarios adscritos al CSIC pertenecientes a las escalas de Titulados Superiores Especializados y Técnicos Especialistas de Grado Medio de los OPIs, con titulaciones universitarias (Licenciados, Ingenieros, Ingenieros Técnicos) e incluso grado de Doctor.Tras la reunión mantenida en Madrid el día 18 de enero de 2005 por un grupo de 9 personas pertenecientes a las Escalas de Técnicos Especialistas de Grado Medio (antes denominados Titulados Técnicos Especializados) y Titulados Superiores del Consejo Superior de Investigaciones Científicas (CSIC), con el Excmo. Sr. Secretario de Estado de Universidades e Investigación del Ministerio de Educación y Ciencia, D. Salvador Ordóñez Delgado, se ha elaborado el presente informe sobre la situación actual, propuestas de modificación sobre la promoción profesional y retribución económica de las Escalas Técnicas del CSIC, por petición expresa del Excmo. Sr. Secretario de Estado. En este informe se detalla la problemática que nos llevo a solicitar dicha reunión, y se presenta una propuesta de modificación de la actual RPT junto con una vía de promoción profesional y económica, con el debido reconocimiento del trabajo desarrollado por las Escalas Técnicas, tan poco reconocido dentro del máximo organismo de investigación en España, como es el Consejo Superior de Investigaciones Científicas.Peer reviewe

Template-controlled acidity and catalytic activity of ferrierite crystals

A synthesis strategy to tailor the acid sites location in ferrierite crystals has been developed. The zeolite catalysts were synthesised in fluoride medium using different combinations of organic structure directing agents (SDAs) in the absence of inorganic cations. Therefore, the negative charge associated to the incorporation of aluminium to the framework was compensated exclusively by the positive charge of the organic SDAs. In this way, Al sitting in the zeolite framework was driven by the specific location of the different SDA molecules within the zeolite void volume. Following this synthesis strategy, it has been found that the distribution of strongly acidic hydroxyl groups in the proton form of the zeolites obtained after removal of the organic templates was dependent on the combination of organic molecules used as SDAs. Moreover, the catalytic activity of the zeolites in m-xylene and 1-butene isomerisation increased as the relative population of strong Brönsted acid groups in sterically constrained sites inside the ferrierite cavity decreased.This work has been financially supported by the MICINN (project CTQ2006-06282).Peer reviewe

Zeolita con fósforo de tipo estructural CON, su preparación y su utilización en craqueo catalítico

Traducción de Patente Europea E98400098 (fecha de solicitud, 20/01/1998).-- Prioridad: FR199701279700980 .-- Titular: Institut Français du PétroleLa presente invención se refiere a una nueva zeolita con fósforo multidimensional de grandes poros de tipo estructural CON, a su preparación y a su utilización particularmente en un procedimiento de craqueo catalítico de una carga hidrocarbonada. Más precisamente, la invención se refiere a un tamiz molecular, borosilicato que puede ser transformado en un aluminosilicato y estabilizado por al menos un compuesto fosforado.Peer reviewe

Influence of Al distribution and defects concentration of ferrierite catalysts synthesized from Na-free gels in the skeletal isomerization of n-butene

The skeletal isomerization of n-butenes to isobutene has been carried out over ferrierite catalysts (Si/Al ~ 15) containing different acid sites distribution and different amount of defects. The zeolite crystals were synthesized under hydrothermal conditions in fluoride medium in the absence of alkaline cations by using suitable combinations of structure directing agents. Template-driven low density of acid sites in 10-membered-ring channels enhances the isobutene selectivity and decreases catalyst deactivation. The presence of high amount of silanol groups and Lewis acid sites increases the yields of by-products and catalysts decay.MICINN (CTQ2006-06282) CSIC (JAE-doc contract)Peer reviewe

Estudio de la ferrierita como catalizador en la reacción de metanol a gasolina

Trabajo presentado en la Reunión de la Sociedad Española de Catálisis, SECAT'15, celebrada en Barcelona (España) del 13 al 15 de julio de 2015.El interés sobre el proceso de transformación de metanol a gasolina (MTG), descubierto por investigadores de la Mobil en la década de los 70 del siglo pasado [1,2], ha vuelto a resurgir en los últimos años como una alternativa viable al refino de petróleo para la obtención de gasolina, tanto por motivos económicos como medioambientales. Si bien el catalizador desarrollado por Mobil, la zeolita ZSM-5, presenta notables prestaciones en cuanto a selectividad y estabilidad, las investigaciones recientes se han centrado en el desarrollo de catalizadores aún más eficientes. La zeolita Ferrierita es un aluminosilicato cristalino que posee una combinación de dos tipos de canales en su estructura, con un tamaño de poro similar al de la ZSM-5 [3]. Recientemente se ha demostrado, en esta zeolita, la posibilidad de controlar, mediante síntesis, la localización preferente de los centros ácidos, activos para la reacción de MTG, en distintas posiciones de la red cristalina de la zeolita [4,5]. En este sentido, la utilización de catalizadores de Ferrierita con una distribución de centros ácidos controlada, podría ser ventajosa en la reacción de MTG como posibles catalizadores más selectivos y más resistentes a la desactivación por coque.Este trabajo ha sido financiado en parte por el MINECO (Proyecto MAT2012-31127).Peer Reviewe

Tailoring the acid strength of microporous silicoaluminophosphates through the use of mixtures of templates: Control of the silicon incorporation mechanism

SAPO-5 samples have been synthesized with triethylamine (TEA), benzylpyrrolidine (BP) and mixtures of them as structure directing agents (SDAs). It has been observed that in the as-synthesised materials the concentration of SDAs (molecules per unit cell) and the Si content are similar. According to the different molecular size of both SDAs, the samples exhibit higher organic weight and lower water content as the molar fraction of BP in the synthesis gel increases. These differences in selectivity for organic/water incorporation influences the mechanism of Si substitution in the AlPO lattice: the higher organic content obtained at higher BP/TEA ratio leads to the formation of large Si islands, while the higher water content of the sample obtained with TEA enhances the formation of isolated Si(OAl)4 environments. Interestingly, it has been found that these two opposite trends can be tailored to a certain point by using mixtures of both SDAs, TEA and BP, in the required ratio. The catalytic activity of the samples has been tested in the isomerisation of m-xylene. It has been observed a higher activity of samples obtained with BP as the main SDA, thus evidencing the better performance of large Si islands in this reaction.MEC (CTQ2006-06282)Peer reviewe

Tuning acid sites distribution of zeolite ferrierite and impact on its catalytic performance

Trabajo presentado en el 5th Serbian-Croatian-Slovenian Symposium on Zeolites, celebrado en Zlatibor (Serbia) del 30 de mayo al 2 de junio de 2013.Zeolite ferrierite has been synthesized following our synthesis strategy to control the distribution of acid sites in the zeolite framework. Different combinations of two templates have been employed as structure directing agents, in the absence of inorganic cations. The amount of bridging OH groups inside the ferrierite cavity, accessible only through 8-ring windows, relative to that in the 10-ring channels, has been found to strongly depend on the specific combination of structure directing agents employed in the synthesis. A good correlation between the acid sites accessibility and catalytic activity has been found. The catalytic performance of ferrierite samples prepared following our synthesis strategy has advantages compared to that of ferrierite obtained following the conventional procedure, employing pyrrolidine as structure directing agent, and in the presence of sodium. This synthesis route may be extended to other suitable zeolite materials.A.B.P. is thankful for the support of the European Community under a Marie Curie Intra−European Fellowship for Career Development (7th Framework Programme). Funding from the Spanish Ministry of Economy (project MAT2012−31127) is greatly acknowledged.Peer Reviewe