Hierarchical Assembly of Zeolite Nanoparticles into Ordered Macroporous Monoliths Using Core−Shell Building Blocks

Rhodes, Katja H.; Davis, Sean A.; Caruso, Frank; Zhang, Baojian; Mann, Stephen

doi:10.1021/cm000438y

Cited by 307 publications

(202 citation statements)

References 38 publications

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“…Because the molecular size of polyolefins is larger than the pore size, cracking of polyolefins occurs mainly over the acid sites on the external surface, followed by the -20-formation of lighter olefins on the internal pore surface. Recently, hierarchical-structured zeolites have attracted attention because nano-pores (called as nanomorphic zeolite) [44,45] and meso-pores [46][47][48][49][50][51][52] are formed among nano-zeolite crystals. The hierarchical materials composed of nano-sized zeolites possess two main advantages: a large external surface area ascribable to nano-zeolite, and larger pores than the zeolitic pore allowing large molecules to reach active sites.…”

Section: Catalytic Reactionmentioning

confidence: 99%

Size-Controlled Synthesis of Nano-Zeolites and Their Application to Light Olefin Synthesis

et al. 2012

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For the application of zeolites as heterogeneous catalysts, low diffusion resistance for hydrocarbons within the micropore is essential for improving product selectivity and catalyst lifetime. This problem has been overcome by reducing the crystal size. This review introduces size-controlled preparation of nano-sized zeolites via hydrothermal synthesis in water/surfactant/organic solvent (emulsion method) and their application to heterogeneous catalysts. The ionicity of the hydrophilic group in surfactant molecules and the concentration of the Si source affected the crystallinity and morphology of zeolites prepared using the emulsion method. When using a non-ionic surfactant, mono-dispersed silicalite-1 nanocrystals approximately 60 nm in diameter were successfully prepared. Nano-and macro-ZSM-5 zeolites with crystal sizes of approximately 150-200 nm and 1.5 µm, respectively, were prepared and applied to n-hexane cracking and acetone-to-olefin reactions to investigate the effect of zeolite crystal size on catalytic stability and light olefin yield. Application of nano-zeolite to light olefin production was effective in achieving faster mass transfer of hydrocarbon molecules within the micropore, which led to improvements in olefin yields and catalyst lifetime.

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Section: Catalytic Reactionmentioning

confidence: 99%

Size-Controlled Synthesis of Nano-Zeolites and Their Application to Light Olefin Synthesis

et al. 2012

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“…[40] Consequently, considerable research efforts are dedicated to the design of novel routes for the preparation of zeolites with hierarchical pore structures, adjustable size and morphology, uniform crystallographic orientation, and ordered arrangement, [41][42][43] as these features are essential for emerging applications as advanced catalysts, chemical sensors, highly selective membranes, optical materials, and low dielectric materials for microelectronics. [44,45] Great success has been achieved on the control of hierarchical pore structure, size, and morphology of zeolite products [43,46,47] yet relatively less progress has been made on the alignment of the nanoor micro-zeolites into uniformly oriented and/or highly ordered arrays. [48] Xia et al [49] reported the first synthesis of 3D ordered arrays of nanozeolites with uniform size and crystallographic orientation, and adjustable overall shape by a simple hydrothermal coupled dissolution-reprecipitation pseudomorphic replacement route (Fig.…”

Section: Transformation Of Leucite (Kalsi 2 O 6 ) To Analcite (Naalsimentioning

confidence: 99%

A Novel Route for the Synthesis of Mesoporous and Low-Thermal Stability Materials by Coupled Dissolution-Reprecipitation Reactions: Mimicking Hydrothermal Mineral Formation

Brugger

McFadden

Lenehan

et al. 2010

Chimia

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Replacement reactions ('pseudomorphism') commonly occur in Nature under a large range of conditions (T 25 to >600 ˚C; P 1 to >5 kbar). Whilst mineral replacement reactions are often assumed to proceed by solid-state diffusion of the metal ions through the mineral, many actually proceed via a coupled dissolution and reprecipitation (CDR) mechanism. In such cases, a starting mineral is dissolved into a fluid and this dissolution is coupled with the precipitation of a replacement phase across the reaction front. In cases where there are close relationships between the crystal structures of the parent and newly formed minerals, the replacement can be topotactic (interface-coupled dissolution and reprecipitation). The kinetics and chemistry of the CDR route are fundamentally different from solid-state diffusion and can be exploited i) for the synthesis of materials that are often difficult to synthesise via traditional methods and ii) to obtain materials with unique properties. This review highlights recent research into the use of CDR for such synthetic challenges. Emphasis has been given to i) the use of CDR to synthesise compounds with relatively low thermal stability such as the thiospinel mineral violarite ((Ni,Fe) 3 S 4 ), ii) preliminary work into use of CDR for the production of roquesite (CuInS 2 ), a potentially important photovoltaic component and, iii) examples where the textures resulting from CDR reactions are controlled by the nature and texture of the parent phase and the reaction conditions; these being the formation of micro-porous gold and three-dimensional ordered arrays of nanozeolite of uniform size and crystallographic orientation.

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“…4 However, as far as we know, there is only one report dealing with a solid including a trimodal pore system. 5 The described synthesis approaches are usually based on the use of so many different template agents as pore types. On the other hand, shaping of porous solids in the form of monoliths instead of fine powders (as usually produced) confers on them additional advantages and wide-ranging applications in catalysis.…”

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confidence: 99%

“…On the other hand, shaping of porous solids in the form of monoliths instead of fine powders (as usually produced) confers on them additional advantages and wide-ranging applications in catalysis. [5][6][7][8] Different research groups have been able to prepare zeolite monoliths with additional macroporous voids by using double scale template agents (small molecular templates and bacterial structures, polystyrene latex spheres or polyurethane foams as secondary large templates), and starting from solutions of inorganic precursors or, alternatively, from preformed zeolite nanoparticles as building blocks. 5,9,10 Polymer foams have been extensively used to synthesize ceramic foams of several compositions.…”

mentioning

confidence: 99%

“…[5][6][7][8] Different research groups have been able to prepare zeolite monoliths with additional macroporous voids by using double scale template agents (small molecular templates and bacterial structures, polystyrene latex spheres or polyurethane foams as secondary large templates), and starting from solutions of inorganic precursors or, alternatively, from preformed zeolite nanoparticles as building blocks. 5,9,10 Polymer foams have been extensively used to synthesize ceramic foams of several compositions. 11 These ceramic materials are usually prepared by coating the surface of the polymer with a slurry of ceramic powder; later polymer removal by calcination leads to a ceramic replica of the organic foam.…”

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confidence: 99%

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Large monolithic silica-based macrocellular foams with trimodal pore system

et al. 2003

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Silica-based materials with hierarchical pore systems at three different length scales (small mesopores-large mesopores-macropores) have been prepared through a nanotectonic approach by using mesoporous nanoparticles as building blocks; the resulting materials present a highly accessible foam-like architecture and can be prepared as large monoliths.The design of new materials with frameworks involving hierarchical pore systems and complex macroscale forms is an emerging area owing to potential applications 1 on the basis of the possibility of harmonizing an enhanced accessibility to the functional active groups (across large pores) with the conservation of the high surface area and pore structure. [2][3][4] These very open networks favour diffusion of reagents and products while avoiding undesired pore blocking phenomena. A variety of bimodal materials combining micro-meso, meso-macro or micro-macroporosity has been described to date. 4 However, as far as we know, there is only one report dealing with a solid including a trimodal pore system. 5 The described synthesis approaches are usually based on the use of so many different template agents as pore types. On the other hand, shaping of porous solids in the form of monoliths instead of fine powders (as usually produced) confers on them additional advantages and wide-ranging applications in catalysis. 5-8 Different research groups have been able to prepare zeolite monoliths with additional macroporous voids by using double scale template agents (small molecular templates and bacterial structures, polystyrene latex spheres or polyurethane foams as secondary large templates), and starting from solutions of inorganic precursors or, alternatively, from preformed zeolite nanoparticles as building blocks. 5,9,10 Polymer foams have been extensively used to synthesize ceramic foams of several compositions. 11 These ceramic materials are usually prepared by coating the surface of the polymer with a slurry of ceramic powder; later polymer removal by calcination leads to a ceramic replica of the organic foam. Lee et al. 8 have recently reported on the use for the first time of polyurethane foams as large-scale secondary templates to prepare micro-macroporous silicalite-1 monoliths using softchemistry conditions typical for obtaining zeolites. In this case, the silicalite crystals grow over the polyurethane surface from a solution confined in the macrocellular voids. In contrast, MCM-41 and related mesoporous materials do not present the ability of zeolites to generate large monoliths and multimodal pore systems. Difficulties increase when nanotectonic approaches are intended, taking into account the unavailability of mesoporous nanoparticles on a large scale. Thus, there is no report to date dealing with the preparation of large monoliths using preformed silica mesoporous nanoparticles as building blocks.Here, we present the preparation and characterization of silica-based large monoliths having trimodal pore systems (small meso-, large meso-and macroporous). The monoliths...

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Hierarchical Assembly of Zeolite Nanoparticles into Ordered Macroporous Monoliths Using Core−Shell Building Blocks

Cited by 307 publications

References 38 publications

Size-Controlled Synthesis of Nano-Zeolites and Their Application to Light Olefin Synthesis

Size-Controlled Synthesis of Nano-Zeolites and Their Application to Light Olefin Synthesis

A Novel Route for the Synthesis of Mesoporous and Low-Thermal Stability Materials by Coupled Dissolution-Reprecipitation Reactions: Mimicking Hydrothermal Mineral Formation

Large monolithic silica-based macrocellular foams with trimodal pore system

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