A two dimensional zeolite with the topology of MWW sheets has been obtained by direct synthesis with a combination of two organic structure directing agents. The resultant material is formed in about 70% by single and double layers with a well structured external surface area of about 300 m2·g-1. The delaminated zeolite prepared by means of this single step synthesis route presents not only a high delamination degree, but a well preserved structural integrity of the MWW layers. It presents an excellent activity, selectivity and catalyst life for alkylation of benzene with propylene, being better than catalysts used today for producing cumene.The importance of zeolites as adsorbents and heterogeneous catalysts is well recognized [1]. When used as catalysts, the microporous structure of these crystalline solids confers the reactants a confined environment that, besides pre-activating the molecules, may direct the reaction towards the formation of the desired products by stabilizing the reaction transition states. However, the narrow pore dimensions of most of the zeolites, in the range of 4 to 7 Å, limit their use to processes involving relatively small molecules. Many efforts have been directed to increase the accessibility to the active sites, and to reduce the diffusional problems of bulkier reactants while preserving a degree of confinement. Traditionally, the accessibility to the active sites has been increased by means of post-synthesis methods that combine acid and hydrothermal treatments, such as in ultra-stabilized Y based catalysts for FCC [2] or mordenite based catalysts for hydroisomerization [1,3], or by combining acid and basic treatments [4]. These top-down procedures are effective but enclose several steps and, depending on the conditions employed, may result in crystallinity and micropore volume loss. Addition of soft or hard templates to the synthesis gel has also been described as a possible route to obtain hierarchical zeolites presenting micro and mesoporosity [4b, 5]. Direct synthesis of single layers of ZSM-5 was achieved by using diquaternary ammonium surfactants and tetraalkylphosphonium as directing agents (OSDA) [6]. The use of these type of OSDAs has also allowed the synthesis of other micro-mesoporous zeolites, with structural mesoporosity [7] or intercrystalline mesoporosity due to small crystallite size [8].A different approach for increasing zeolite's accessibility was described in the middle 1990's, and consisted in the delamination of layered zeolite precursors. The concept was proved to be applicable to different structures, and new delaminated zeolites ITQ-2 [9], [10], were prepared starting from MCM-22(P), PRE-FER, NU-6(1), and ITQ-19, respectively [13]. The resultant zeolitic materials showed very high accessible surface areas and interesting catalytic properties for a large number of reactions [14]. The first of those delaminated zeolites described, ITQ-2, is formed by disordered MWW layers in a "house of

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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.

DS-ITQ-2 has been proposed as catalyst for the Diels–Alder (DA) reaction between 2,5-dimethylfuran and ethylene to produce p-xylene based on the fact that the organic molecule employed for its synthesis mimics the DA intermediate cycloadduct.

Transalkylation of alkylaromatics catalyzed by acid zeolites is a process widely employed in the petrochemical industry for upgrading aromatic fractions. The reaction mechanism is complex as it can proceed either by intermolecular alkyl-transfer involving dealkylation-alkylation steps with surface alkoxy species as reaction intermediates, or through the formation of bulkier diaryl intermediates. We have investigated how the possible formation of such bulky intermediates in the microporous channel system of different zeolite structures, together with their stabilization by confinement effects, can determine the preferential mechanism and, therefore, the selectivity of ethylbenzene disproportionation into benzene and diethylbenzene. For testing the concept, four zeolites, MCM-22 (3D MWW) with 10R pores, 12R cavities and external 12R hemicavities or "cups", DS-ITQ-2, a 2D MWW with the same 10R channels as MCM-22, no 12R cavities and much larger proportion of external "cups", a 10R ZSM-5 (MFI) and a 12R mordenite (MOR) have been used. The higher activity of DS-ITQ-2 and MCM-22 as compared to ZSM-5, at low temperature (573 k) and the high selectivity to diethylbenzene of the bidimensional material under all reaction conditions considered have been explained by means of DFT calculations. Contrary to what could be expected according to the available space at the external "cups" and at the 10R channels of the MWW structure, the bulkier diaryl intermediates are better stabilized within the 10R channel system than at the "cups" open at the external surface of the MWW materials. We show from this perspective how the channel structure and molecular confinement stabilization also explain the operating reaction mechanism in ZSM-5 and mordenite.

A two dimensional zeolite with the topology of MWW sheets has been obtained by direct synthesis with a combination of two organic structure directing agents. The resultant material is formed in about 70% by single and double layers with a well structured external surface area of about 300 m2·g-1. The delaminated zeolite prepared by means of this single step synthesis route presents not only a high delamination degree, but a well preserved structural integrity of the MWW layers. It presents an excellent activity, selectivity and catalyst life for alkylation of benzene with propylene, being better than catalysts used today for producing cumene.The importance of zeolites as adsorbents and heterogeneous catalysts is well recognized [1]. When used as catalysts, the microporous structure of these crystalline solids confers the reactants a confined environment that, besides pre-activating the molecules, may direct the reaction towards the formation of the desired products by stabilizing the reaction transition states. However, the narrow pore dimensions of most of the zeolites, in the range of 4 to 7 Å, limit their use to processes involving relatively small molecules. Many efforts have been directed to increase the accessibility to the active sites, and to reduce the diffusional problems of bulkier reactants while preserving a degree of confinement. Traditionally, the accessibility to the active sites has been increased by means of post-synthesis methods that combine acid and hydrothermal treatments, such as in ultra-stabilized Y based catalysts for FCC [2] or mordenite based catalysts for hydroisomerization [1,3], or by combining acid and basic treatments [4]. These top-down procedures are effective but enclose several steps and, depending on the conditions employed, may result in crystallinity and micropore volume loss. Addition of soft or hard templates to the synthesis gel has also been described as a possible route to obtain hierarchical zeolites presenting micro and mesoporosity [4b, 5]. Direct synthesis of single layers of ZSM-5 was achieved by using diquaternary ammonium surfactants and tetraalkylphosphonium as directing agents (OSDA) [6]. The use of these type of OSDAs has also allowed the synthesis of other micro-mesoporous zeolites, with structural mesoporosity [7] or intercrystalline mesoporosity due to small crystallite size [8].A different approach for increasing zeolite's accessibility was described in the middle 1990's, and consisted in the delamination of layered zeolite precursors. The concept was proved to be applicable to different structures, and new delaminated zeolites ITQ-2 [9], [10], were prepared starting from MCM-22(P), PRE-FER, NU-6(1), and ITQ-19, respectively [13]. The resultant zeolitic materials showed very high accessible surface areas and interesting catalytic properties for a large number of reactions [14]. The first of those delaminated zeolites described, ITQ-2, is formed by disordered MWW layers in a "house of cards" disposition. The layers, with a 2.5 nm thickness, pr...

Ferrierite zeolites with nanosized crystals and external surface areas higher than 250 m 2 ·g -1 have been prepared at relatively low synthesis temperature (120ºC) 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, increasing the number of pores accessible and reducing their average pore length to 10-30 nm. 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.Zeolites are microporous silico-aluminates with crystalline structures presenting well defined channels and cavities of molecular dimensions, [1] widely employed as adsorbents, ion exchangers and for gas separation or refining, petrochemical and environmental catalytic applications [2] due to their molecular sieve and shape selectivity effects [3] . Nevertheless, based on confinement effects, a new concept and methodology for the "Ab initio" synthesis of zeolites for preestablished catalytic reactions has been reported very recently [4] . In processes dealing with bulky molecules, their microporous structure may impose diffusional problems and underuse of the overall micropore volume, directly affecting activity, selectivity and deactivation rate. Among the different approaches proposed to increase the accessibility to the zeolites active sites [5] , the generation of inter-crystalline mesoporosity by reducing the crystallite size from the micro-to the nanoscale [5d, 6] has been thoroughly explored in the last years.Ferrierite [FER] is a zeolite with a bidirectional microporous structure formed by interconnected medium (10-ring, 4.2 x 5.4 Å) and small (8-ring, 3.5 x 4.8 Å) pores. Along the 8-ring channels a cavity is formed, accessible only through 8-ring windows, and known as the FER cage [7] . This zeolite, highly stable towards thermal, hydrothermal and chemical treatments, has been applied as catalyst in different processes, such as isomerization of n-butenes [8] and others [9] .Although highly selective, the topology and pore dimensions of ferrierite limits the reaction to the active sites closer to the crystal surface and results in fast deactivation due to pore blocking with coke precursors. One possible solution would be to decrease the diffusional path lengths. Thus, a delaminated FER, ITQ-6, was obtained by delamination of a layered precursor (PREFER) [10] , following a procedure similar to the one used for preparing zeolite ITQ-2 [6] . When efficiently delaminated, ITQ-6 is highly active for the conversion of bulky reactants [10b] due to its high external sur...

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