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Fluidized Catalytic cracking (FCC) is one of the main conversion processes in conventional refineries and employs a multicomponent catalyst with Y zeolite as the main source of activity and selectivity towards value added products. In order to meet the severe requirements of the FCC unit, the hydrothermal stability of this large pore zeolite is traditionally improved by means of controlled hydrothermal treatments that can be combined with acid washing cycles, with rare earth (RE) ion exchange or with a combination of both. Phosphorus has also been described as a hydrothermal stabilization element. Although most of the studies are based on ZSM-5 zeolites, a new Y zeolite containing FCC catalyst, Phinesse, was developed recently. This catalyst, based on the partial substitution of RE by P allowed obtaining the same activity and the same yields to the main products as its conventional RE stabilized counterpart in the catalytic cracking of a vacuum gas oil (VGO). In this work, we present a systematic study where the hydrothermal stability of P- and La-free USYs with different dealumination degrees is compared with that of the corresponding USYs containing P or La alone or a combination of both stabilizing elements. The samples have been thoroughly characterized and their catalytic performance has been tested in a MAT unit. According to the results obtained, when using RE alone, only high contents (> 3.5 wt% RE) are able to stabilize the catalysts towards steaming under severe conditions (100% steam, 750 ºC). However, lower RE ( wt%) can lead to similar hydrothermal stabilization when combined with intermediate phosphorus contents (∼1.0 wt%). The results obtained provide the bases for understanding the reasons behind the benefits of this combined P-La stabilization observed for the commercial Phinesse™ catalyst as compared to a high REO catalyst. more...

This work explores the synergies during combined reactions of n-pentane (nC) with oxygenates (methanol or dimethyl ether, OX). The experimental runs have been carried out in a packed bed reactor at 500 °C, using a high silica HZSM-5 zeolite-based catalyst with different oxygenate-to-n-pentane (OX/nC) ratios in the feed. A significant enhancement of the n-pentane conversion occurs for low OX/nC ratios in the feed (0.1−0.25), especially when using dimethyl ether (DME). In addition, the presence of n-pentane reduces the rate of catalyst deactivation by coking during the conversion of oxygenates. These results have been explained on the grounds of a mechanistic interaction between the reactants: (1) the fast formation of methoxy and olefin intermediates from oxygenates, particularly from DME, could explain the promotion of n-pentane cracking, by facilitating the activation of the alkane by hydrogen transfer reactions; (2) the attenuation of deactivation during the conversion of oxygenates could be related to a lower extent of the arene cycle in the dual-cycle mechanism (limiting the polymethylbenzene formation). The analyses of used catalysts by means of temperature-programmed oxidation and confocal fluorescence microscopy have pointed out the higher reactivity of DME than that of methanol also for yielding coke structures. more...

As one of the most influential scientists in the field of heterogeneous catalysis and materials science, Prof. Avelino Corma has made significant contributions in many diverse fields, spanning over solid catalysts for petrochemistry, solid catalysts for production of fine chemicals, synthesis of microporous and mesoporous materials, development of inorganic-organic hybrid materials, supported metal catalysts (from isolated metal atoms to nanoclusters and nanoparticles) and photochemistry with solid materials. These experimental approaches are complemented with characterization of solid materials with advanced spectroscopy and microscopy techniques as well as theoretical calculations/modeling. The aim of this Account is to overview Avelino's distinguished scientific career and highlight the most remarkable achievements made in his research activities during >40 years. We attempt to show the evolution of Avelino's research topics in his group throughout his career and the approaches that Avelino has chosen to tackle the challenges encountered. The research paradigm developed by Avelino and his team can be inspiring to the researchers in the field of materials science who are striving to translate the knowledge generated in fundamental studies into practical applications for addressing the new scientific challenges encountered in building a sustainable world. more...

Methane, the main component of natural gas, is an interesting source of chemicals and clean liquid fuels, and a promising alternative raw material to oil. Among the possible direct routes for methane conversion, its aromatization under non-oxidative conditions has received increasing attention, despite the low conversions obtained due to thermodynamic limitations, because of its high selectivity to benzene. Mo/H-ZSM-5, the first bifunctional zeolite-catalyst proposed for this reaction, is still considered as one of the most adequate and has been widely studied. Although the mono-or bifunctional nature of the MDA mechanism is still under debate, it is generally accepted that the Mo species activate the C-H bond in methane, producing the intermediates. These will aro-matize on the Brønsted acid sites of the zeolite, whose pore dimensions will provide the shape selectivity needed for converting methane into benzene. An additional role of the zeolite’s Brønsted acid sites is to promote the dispersion of the Mo oxide precursor. Here, we show the influence of the different preparation steps—metal incorporation, calcination and activation of the Mo/ZSM-5-on the metal dispersion and, therefore, on the activity and selectivity of the final catalyst. Metal dispersion is enhanced when the samples are calcined under dynamic conditions (DC) and acti-vated in N2, and the benefits are larger when the metal has been incorporated by solid state reaction (SSR), as observed by FESEM-BSE and H2-TPR. This leads to catalysts with higher activity, increased aromatic selectivity and improved stability towards deactivation. more...

The hydrogenation activity and physico-chemical characterization of a series of NiMo catalyst supported on materials with different acid-base properties (AlO, layered double hydroxides-derived MgAl oxides and MgO) have been investigated. The results show a clear correlation between the electrodonor capacity of the support, the negative charge density of the supported NiMo oxides and the intrinsic hydrogenation rate of the sulfided phase. Spectroscopic characterization ruled out any possible contribution derived from differences in the NiMoS stack or slab size distributions, as determined by high-resolution transmission electron microscopy. The experimental results obtained suggest the occurrence of an electron transfer phenomena from the support to the supported NiMoS slabs, being this effect stronger for supports with higher electrodonor capacity. This work presents a specific electronic support effect that goes beyond the classical dispersing and stabilizing role. more...

Microporous zeolite-type materials, with crystalline porous structures formed by well-defined channels and cages of molecular dimensions, have been widely employed as heterogeneous catalysts since the early 1960s, due to their wide variety of framework topologies, compositional flexibility and hydrothermal stability. The possible selection of the microporous structure and of the elements located in framework and extraframework positions enables the design of highly selective catalysts with well-defined active sites of acidic, basic or redox character, opening the path to their application in a wide range of catalytic processes. This versatility and high catalytic efficiency is the key factor enabling their use in the activation and conversion of different alkanes, ranging from methane to long chain n-paraffins. Alkanes are highly stable molecules, but their abundance and low cost have been two main driving forces for the development of processes directed to their upgrading over the last 50 years. However, the availability of advanced characterization tools combined with molecular modelling has enabled a more fundamental approach to the activation and conversion of alkanes, with most of the recent research being focused on the functionalization of methane and light alkanes, where their selective transformation at reasonable conversions remains, even nowadays, an important challenge. In this review, we will cover the use of microporous zeolite-type materials as components of mono- and bifunctional catalysts in the catalytic activation and conversion of C1+ alkanes under non-oxidative or oxidative conditions. In each case, the alkane activation will be approached from a fundamental perspective, with the aim of understanding, at the molecular level, the role of the active sites involved in the activation and transformation of the different molecules and the contribution of shape-selective or confinement effects imposed by the microporous structure. more...

A method of forming a composite zeolite catalyst includes combining a silicon source and an aqueous organic structure directing agent having a polyamino cation compound to form a silica intermediary gel, introducing an aluminum precursor to the silica intermediary gel to form a catalyst precursor gel, evaporating water in the catalyst precursor gel to form a catalyst gel, and heating the catalyst gel to form a composite zeolite catalyst particle having an intergrowth region with a mixture of both Beta crystals and ZSM-5 crystals. An associated method of making xylene includes feeding heavy reformate to a reactor, the reactor containing the composite zeolite catalyst, and producing xylene by simultaneously performing dealkylation and transalkylation of the heavy reformate in the reactor, where each composite zeolite catalyst particle is able to catalyze both the dealkylation and transalkylation reactions more...

A composite zeolite catalyst particle having an intergrowth region with a mixture of both Beta crystals and ZSM-5 crystals. An associated method of making xylene includes feeding heavy reformate to a reactor, the reactor containing the composite zeolite catalyst, and producing xylene by simultaneously performing dealkylation and transalkylation of the heavy reformate in the reactor, where each composite zeolite catalyst particle is able to catalyze both the dealkylation and transalkylation reactions more...

A method of forming composite zeolite catalyst particles includes combining a silicon source, an aqueous organic structure directing agent having a polyquaternary ammonium compound, water and an aluminum source to form a catalyst gel. The method also includes heating the catalyst gel to form the composite zeolite catalyst particle having an intergrowth region with a mixture of both Mordenite crystals and ZSM-5 crystals. An associated method of making xylene includes feeding heavy reformate to a reactor, the reactor containing the composite zeolite catalyst particles, and producing xylene by simultaneously performing dealkylation and transalkylation of the heavy reformate in the reactor, where each composite zeolite catalyst particle is able to catalyze both the dealkylation and transalkylation reactions more...

A method of making BTX (benzene, toluene, xylene) compounds by feeding a heavy reformate stream to a reactor, where the reactor includes a composite zeolite catalyst, that contains a mixture of a desilicated mesoporous mordenite and ZSM-5, and in which the desilicated mesoporous mordenite, the ZSM-5, or both, comprise one or more impregnated metals. The composite zeolite catalyst is able to catalyze the transalkylation reaction and the dealkylation reaction simultaneously to produce the BTX compounds more...

A method of forming composite zeolite catalyst particles includes combining a silicon source, an aqueous organic structure directing agent having a polyquaternary ammonium compound, water and an aluminum source to form a catalyst gel. The method also includes heating the catalyst gel to form the composite zeolite catalyst particle having an intergrowth region with a mixture of both Mordenite crystals and ZSM-5 crystals. An associated method of making xylene includes feeding heavy reformate to a reactor, the reactor containing the composite zeolite catalyst particles, and producing xylene by simultaneously performing dealkylation and transalkylation of the heavy reformate in the reactor, where each composite zeolite catalyst particle is able to catalyze both the dealkylation and transalkylation reactions more...

A method of forming a composite zeolite catalyst includes combining a silicon source and an aqueous organic structure directing agent having a polyamino cation compound to form a silica intermediary gel, introducing an aluminum precursor to the silica intermediary gel to form a catalyst precursor gel, evaporating water in the catalyst precursor gel to form a catalyst gel, and heating the catalyst gel to form a composite zeolite catalyst particle having an intergrowth region with a mixture of both Beta crystals and ZSM-5 crystals. An associated method of making xylene includes feeding heavy reformate to a reactor, the reactor containing the composite zeolite catalyst, and producing xylene by simultaneously performing dealkylation and transalkylation of the heavy reformate in the reactor, where each composite zeolite catalyst particle is able to catalyze both the dealkylation and transalkylation reactions more...

The present invention relates to a new process for synthesising a crystalline material comprising structure Beta zeolite in nanocrystalline form, and which can comprise at least the following steps: (i) preparing a mixture comprising at least one source of water, at least one source of a tetravalent element Y, at least one source of a trivalent element X, at least one source of an alkali cation or alkaline earth metal cation (A), and at least one organic molecule selected from a monocyclic quaternary ammonium R1R2CycloN+, and a quaternary ammonium substituted with a cycloalkyl group R3R4R5R6N+. The molar composition of the mixture is: n X2O3:YO2:a A:m OSDA1:z H2O; ii) crystallising the mixture; and iii) recovering the crystalline material more...

Procedimiento de síntesis de un material con estructura zeolítica MWW en su forma nanocristalina, que comprende los siguientes pasos: i) Preparación de una mezcla que comprenda una fuente de agua, al menos una fuente de un elemento tetravalente Y, al menos una fuente de un elemento trivalente X, al menos una fuente de un catión alcalino o alcalinotérreo (A), y al menos dos moléculas orgánicas (ADE01 y ADE02), donde ADE01 es un amonio cuaternario monocíclico en que uno de los sustituyeles es una cadena alquílica de 3-6 átomos de carbono, y ADE02 está seleccionado entre cualquier amina o amonio capaz de dirigir la formación de MWW. ¡i) Cristalización de la mezcla obtenida en i) en un reactor iü) Recuperación del material cristalino obtenido en ¡i). [ES], The invention relates to a method for synthesising a material with an MWW zeolite structure in its nanocrystalline form, which comprises the following steps: i) preparing a mixture comprising a water source, at least one source of a tetravalent element Y, at least one source of a trivalent element X, at least one source of an alkaline cation or alkaline earth metal cation (A), and at least two organic molecules (ADE01 and ADE02), wherein ADE01 is a monocyclic quaternary ammonium in which one of the substituents is an alkyl chain of 3-6 carbon atoms, and ADE02 is selected from any amine or ammonium able to direct the formation of MWW; ii) crystallising the mixture obtained in step i) in a reactor; and iii) recovering the crystalline material obtained in step ii). [EN] more...

Procedimiento de síntesis del material MWW en su forma nanocristalina y su uso en aplicaciones catalíticas. Procedimiento de síntesis de un material con estructura zeolítica MVWV en su forma nanocristalina, que comprende los siguientes pasos: i) Preparación de una mezcla que comprenda una fuente de agua, al menos una fuente de un elemento tetravalente Y, al menos una fuente de un elemento trivalente X, al menos una fuente de un catión alcalino o alcalinotérreo (A), y al menos dos moléculas orgánicas (ADEO1 y ADEO2), donde ADEO1 es un amonio cuaternario monocíclico en que uno de los sustituyentes es una cadena alquílica de 3-6 átomos de carbono, y ADEO2 está seleccionado entre cualquier amina o amonio capaz de dirigir la formación de MWW. ii) Cristalización de la mezcla obtenida en i) en un reactor. iii) Recuperación del material cristalino obtenido en ii). more...

In the present manuscript, the influence of the zeolite structure and crystal size on bifunctional tandem catalysts combining K-promoted iron oxide (K/Fe3O4) with different zeolites has been studied for the CO2 hydrogenation reaction at 320 °C and 25 bar. First, to evaluate the influence of the zeolite structure on CO2 conversion, three different zeolite topologies have been evaluated (BEA, MFI and CHA) with similar Si/Al molar ratios. The combination of K/Fe3O4 with MFI maximizes the formation of aromatic products, while its combination with CHA and BEA increases the C1-C4 gas fractions, with a high olefin selectivity. In addition, aromatics and aliphatic hydrocarbons are present in the condensed liquids of the tandem catalysts containing BEA, while no aromatics are observed for those with CHA. These different product selectivities can be ascribed to the different consecutive reactions within the three zeolites, where MFI favors the aromatization of alkenes, and BEA and CHA favor oligomerization/cracking reactions leading to an increase of light olefin yield. Second, the evaluation of the nanosized form of the three proposed zeolite frameworks has also been carried out. The reduction of the particle size allows for increasing light olefin selectivity in all cases as compared to zeolites with larger crystals. Shorter intracrystalline diffusion paths facilitate the egression of light olefins before being involved in consecutive oligomerization reactions. In the particular case of the tandem catalysts with nanosized MFI zeolites, the C2-C4 fraction and its olefinicity are increased while maintaining the overall aromatic selectivity comparable to that obtained with micron-sized MFI zeolites. more...

The characterization and catalytic performance of Zn/ZSM-5 and Zn-B/ZSM-5 catalysts in the n-hexane aromatization was reported. Catalysts were prepared by post-synthesis ion exchange and thoroughly characterized by means of XRD, Py-FTIR, N adsorption, Al and B MAS NMR spectroscopy and electron microscopy techniques. The incorporation of zinc reduces the Brønsted acid site density and increases the Lewis acidic sites of the final ZSM-5 based catalysts. The presence of boron slightly reduces the initial activity of the catalyst but slows down its deactivation rate. more...

There are a large number of zeolites, such as ITH, that cannot be prepared in the aluminosilicate form. Now, the successful synthesis of aluminosilicate ITH zeolite using a simple cationic oligomer as an organic template is presented. Key to the success is that the cationic oligomer has a strong complexation ability with aluminum species combined with a structural directing ability for the ITH structure similar to that of the conventional organic template. The aluminosilicate ITH zeolite has very high crystallinity, nanosheet-like crystal morphology, large surface area, fully four-coordinated Al species, and abundant acidic sites. Methanol-to-propylene (MTP) tests reveal that the Al-ITH zeolite shows much higher selectivity for propylene and longer lifetime than commercial ZSM-5. FCC tests show that Al-ITH zeolite is a good candidate as a shape-selective FCC additive for enhancing propylene and butylene selectivity. more...

This work explores the synergies during combined reactions of n-pentane (nC5) with oxygenates (methanol or dimethyl ether, OX). The experimental runs have been carried out in a packed bed reactor at 500 °C, using a high silica HZSM-5 zeolite-based catalyst with different oxygenate-to-n-pentane (OX/nC5) ratios in the feed. A significant enhancement of the n-pentane conversion occurs for low OX/nC5 ratios in the feed (0.1−0.25), especially when using dimethyl ether (DME). In addition, the presence of n-pentane reduces the rate of catalyst deactivation by coking during the conversion of oxygenates. These results have been explained on the grounds of a mechanistic interaction between the reactants: (1) the fast formation of methoxy and olefin intermediates from oxygenates, particularly from DME, could explain the promotion of n-pentane cracking, by facilitating the activation of the alkane by hydrogen transfer reactions; (2) the attenuation of deactivation during the conversion of oxygenates could be related to a lower extent of the arene cycle in the dual-cycle mechanism (limiting the polymethylbenzene formation). The analyses of used catalysts by means of temperature-programmed oxidation and confocal fluorescence microscopy have pointed out the higher reactivity of DME than that of methanol also for yielding coke structures. more...

Methods of making BTX compounds including benzene, toluene, and xylene include feeding heavy reformate to a reactor containing a composite zeolite catalyst. The composite zeolite catalyst includes a mixture of SSZ-33 and ZSM-5. The SSZ-33, the ZSM-5, or both comprise one or more impregnated metals. The method further includes producing the BTX compounds by simultaneously performing transalkylation and dealkylation of the heavy reformate in the reactor. The composite zeolite catalyst is able to simultaneously catalyze both the transalkylation and dealkylation reactions more...

A method of forming a composite zeolite catalyst includes combining a silicon source and an aqueous organic structure directing agent having a polyamino cation compound to form a silica intermediary gel, introducing an aluminum precursor to the silica intermediary gel to form a catalyst precursor gel, evaporating water in the catalyst precursor gel to form a catalyst gel, and heating the catalyst gel to form a composite zeolite catalyst particle having an intergrowth region with a mixture of both Beta crystals and ZSM-5 crystals. An associated method of making xylene includes feeding heavy reformate to a reactor, the reactor containing the composite zeolite catalyst, and producing xylene by simultaneously performing dealkylation and transalkylation of the heavy reformate in the reactor, where each composite zeolite catalyst particle is able to catalyze both the dealkylation and transalkylation reactions more...

Method of making BTX compounds including benzene, toluene, and xylene, including feeding heavy reformate to a reactor containing a composite zeolite catalyst. The composite zeolite catalyst includes a mixture of layered mordenite (MOR-L) comprising a layered or rod-type morphology with a layer thickness less than 30 nm and ZSM-5. The MOR-L, the ZSM-5, or both include one or more impregnated metals. The method further includes producing the BTX compounds by simultaneously performing transalkylation and dealkylation of the heavy reformate in the reactor. The composite zeolite catalyst is able to simultaneously catalyze both the transalkylation and dealkylation reactions more...

A method of forming composite zeolite catalyst particles includes combining a silicon source, an aqueous organic structure directing agent having a polyquaternary ammonium compound, water and an aluminum source to form a catalyst gel. The method also includes heating the catalyst gel to form the composite zeolite catalyst particle having an intergrowth region with a mixture of both Mordenite crystals and ZSM-5 crystals. An associated method of making xylene includes feeding heavy reformate to a reactor, the reactor containing the composite zeolite catalyst particles, and producing xylene by simultaneously performing dealkylation and transalkylation of the heavy reformate in the reactor, where each composite zeolite catalyst particle is able to catalyze both the dealkylation and transalkylation reactions more...

[EN] A nanocrystalline zeolite material with a ferrierite structure and the method for synthesising same, comprising at least: i) preparation ofa mixture comprising water, a source ofa tetravalent element Y, a source of a trivalent element X, a source of an alkali or alkaline earth cation (A) and two organic compounds (ADEO 1and ADE02), whereby ADEO 1is selected from amongst a monocyclic qnaternary annnonium salt in which at least one of the substituents attached to the nitro gen is a linear alky 1 chain comprising between 6 and 22 carbon atoms, and ADE02 is selected from amongst an arnine, an ammonium salt or combinations thereof; ii) synthesis of the zeolite starting from the mixture obtained in i); and iii) recovery ofthe crystalline material (ferrierite zeolite) obtained in ii)., [ES] Material zeolítico con la estructura Ferrierita en su forma nanocristalina y su procedimiento de síntesis que comprende al menos: i) preparación de una mezcla que comprenda: agua, una fuente de nn elemento tetravalente Y, una fuente de un elemento trivalente X, una fuente de nn catión alcalino o alcalinotérreo (A), y dos compuestos orgánicos (ADEOl y ADE02), donde ADEOl está seleccionado entre una sal de amonio cuaternario monocíclica donde al menos nno de los sustituyentes unidos al nitrógeno es una cadena alquílica lineal formada por entre 6-22 átomos de carbono, y ADE02 está seleccionado entre una arnina, una sal de amonio amonio o combinaciones de los mismos, ii) síntesis de la zeolita partiendo de la mezcla obtenida en i) y iii) recuperación del material cristalino (zeolita ferrierita) obtenido en ii) more...

Material zeolítico con estructura ferrierita en su forma nanocristalina, procedimiento para su síntesis y uso de dicho material. Material zeolítico con la estructura ferrierita en su forma nanocristalina y su procedimiento de síntesis que comprende al menos: i) preparación de una mezcla que comprenda: agua, una fuente de un elemento tetravalente Y, una fuente de un elemento trivalente X, una fuente de un catión alcalino o alcalinotérreo (A), y dos compuestos orgánicos (ADEO1 y ADEO2), donde ADEO1 está seleccionado entre una sal de amonio cuaternario monocíclica donde al menos uno de los sustituyentes unidos al nitrógeno es una cadena alquílica lineal formada por entre 6 - 22 átomos de carbono, y ADEO2 está seleccionado entre una amina, una sal de amonio amonio o combinaciones de los mismos, ii) síntesis de la zeolita partiendo de la mezcla obtenida en i) y iii) recuperación del material cristalino (zeolita ferrierita) obtenido en ii). more...

Ge-containing zeolites were used as precursors for the synthesis of highly conductive and stable hybrid electronic materials by postsynthetic thermal treatment of the crystals in the presence of an olefin. Treating the as-prepared Ge zeolites in 1-butene at 700 °C formed a graphitic matrix within and outside the crystals due to the thermal degradation of the organic structure-directing agent inside the pores and the polymerization of the olefin. Importantly, these conditions forced Ge out of the framework, leading to the collapse of the crystalline structure and subsequent formation of metallic Ge nanoparticles distributed either as small, well-dispersed nanoparticles within the silica matrix or larger carbon-coated core-shell Ge@C nanoparticles on the external surface of the carbon-silica composite. Varying the zeolite topology influenced the size of the Ge@C nanoparticles, with those obtained using the multipore zeolite ITQ-22 (IWW, 12 × 10 × 8 rings) featuring smaller sizes (30-60 nm) than those obtained with the large-pore zeolite ITQ-33 (ITT, 18 × 10 × 10 rings) (80-120 nm), where the lack of diffusional limitations increased metal sintering rates. The zeolite topology also influenced the final carbon content and dispersion of the Ge nanoparticles. The best performing Ge-based hybrid material was obtained by thermal treatment of ITQ-22 (Si/Ge = 4) at 700 °C in 1-butene. Unlike Ge-free hybrid controls, an ITQ-22 (Si/Ge = 4) sample treated at 700 °C in 1-butene showed a conductivity value of ∼2 S/m (measured at 1 V), which is in the range of a commercially available graphene. The simple methodology presented here is an alternative route for the efficient preparation of highly stable Ge-based hybrid composites with excellent conductivity for potential use as high-capacity electrodes. more...

Upgrading of the heavy reformate fraction (HR), containing mainly C aromatics, is usually performed by dealkylation or by transalkylation with added benzene and/or toluene to obtain the more valuable xylenes. However, when the costs related to the use of benzene and toluene are considered, the one-step dealkylation/transalkylation of the C alkylaromatics to xylenes becomes economically attractive. Thus, in a first step, ethylmethylbenzenes (EMB) will have to be dealkylated to toluene, which will then react with the trimethylbenzenes (TMB) present in the HR feed to produce xylenes by transalkylation. Medium pore zeolites will favor dealkylation, whereas large pore zeolites will be more adequate for carrying out the transalkylation reaction. In this work, we present the one-pot synthesis of beta-pentasil aggregates with tunable ratios of the large pore beta to the medium pore component. We show that the close proximity of the beta and pentasil nanocrystals obtained by one-pot co-crystallization synthesis, results in a highly efficient catalyst for the consecutive dealkylation/transalkylation process. The bifunctional catalyst based on the co-crystallized aggregate is more active and selective to xylenes than a catalyst based on a physical mixture of equivalent beta and pentasil nanozeolites synthesized following an analogous procedure. The small crystallite sizes of the co-crystallized zeolites provide the additional advantage of a lower deactivation rate as compared to a reference benchmark catalyst. Results are shown on both, model molecules and industrial HR feed. more...

The present invention relates to a new process for synthesising a crystalline material comprising the structure Beta zeolite in nanocrystalline form, and which can comprise at least the following steps: (i) preparing a mixture comprising at least one source of water, at least one source of a tetravalent element Y, at least one source of a trivalent element X, at least one source of an alkali cation or alkaline earth metal cation (A), and at least one organic molecule selected from a monocyclic quaternary ammonium R1R2CycloN+, and a quaternary ammonium substituted with a cycloalkyl group R3R4R5R6N+, the molar composition of the mixture being n X2O3 : YO2 : a A : m ADEO1 : z H2O; (ii) crystallising the mixture; and (iii) recovering the crystalline material. [EN], La presente invención se refiere a un nuevo proceso de síntesis de un material cristalino que presenta la estructura zeoiítica Beta en su forma nanocristalina, y que puede comprender, al menos, los siguientes pasos: i) Preparación de una mezcla que comprenda al menos una fuente de agua, ai menos una fuente de un elemento tetravalente Y, al menos una fuente de un elemento trivalente X, ai menos una fuente de un catión alcalino o alcalinotérreo (A), y al menos una molécula orgánica seleccionada entre un amonio cuaternario monocíclico R1R2CycloN+, y un amonio cuaternario sustituido con un grupo cicloalquílico R3R4R5R6N+. La composición molar de la mezcla es: n X2O3 : YO2 : a A : m ADEO1 : z H2O; ii) Cristalización de dicha mezcla: y iii) Recuperación del material cristalino. [ES] more...

Ferrierite zeolites with nanosized crystals and external surface areas higher than 250 m g have been prepared at relatively low synthesis temperature (120 °C) by means of the collaborative effect of two organic structure directing agents (OSDA). In this way, hierarchical porosity is achieved without the use of post-synthesis treatments that usually involve leaching of T atoms and solid loss. Adjusting the synthesis conditions it is possible to decrease the crystallite size in the directions of the 8- and 10-ring channels, [010] and [001] respectively, reducing their average pore length to 10–30 nm and increasing the number of pores accessible. The small crystal size of the nano-ferrierites results in an improved accessibility of reactants to the catalytic active centers and enhanced product diffusion, leading to higher conversion and selectivity with lower deactivation rates for the oligomerization of 1-pentene into longer-chain olefins. more...