Micron-Sized Single-Crystal-like CoAPO-5/Carbon Composites Leading to Hierarchical CoAPO-5 with Both Inter- and Intracrystalline Mesoporosity

Abstract

Commercial mesopores-containing carbon (carbon black BP2000) has been used as crystallization host as well as hard template of intracrystalline mesopores in CoAPO-5 materials prepared with N-methyldicyclohexylamine as specific structure-directing agent. As a result, micrometer-sized AFIstructured terminated-tip (pencil-like) hexagonal prims have been obtained. Despite the appearance of single crystals, the crystals are actually composites formed by a large number of elongated-shape CoAPO-5 and carbon nanodomains. Indeed, the removal of carbon by calcination leaves an inorganic Codoped AlPO 4 -based material having a complex hierarchical pore system, formed by the expected microporosity for an AFIstructured material and both intra-and intercrystalline mesoporosity. In good agreement with the nanocomposite nature of these micrometer-sized crystals, the size of their fibers generated by burning the carbon matrix can be relatively controlled by the conditions of the calcination processes. Under optimized synthesis and calcination conditions, AFI-structured materials with high mesoporous surface area and pore volume can be afforded.

Hierarchical Silicoaluminophosphates by Postsynthetic Modification: Influence of Topology, Composition, and Silicon Distribution

“…Academic interest in the preparation of SAPO catalysts has predominately focused on tuning hydrothermal synthesis. ,− For example, variation of the components in the synthesis gel and crystallization conditions enables to tailor the type of framework and its composition, , the Si distribution (hence acidity), the crystal size, and the morphology of the resulting solid. Moreover, the inclusion of various metals, like Cu, Co, Mn, and Fe, in the synthesis gel leads to SAPO frameworks with redox properties. , Alternatively, during the past decade, various approaches were devised to tailor the hydrothermal synthesis protocol in order to obtain hierarchically structured SAPOs. − The latter is achieved by addition of organic porogens to the synthesis gel, which are subsequently removed by combustion. The resulting hierarchical SAPOs combine the intrinsic micropores with an auxiliary level of (meso)­porosity, aiming at reducing access and diffusion limitations and subsequently enhancing their performance in catalyzed reactions.…”

Metal-Substituted Microporous Aluminophosphates

“…In spite of the success of this method in the synthesis of nanocrystalline zeolites, it was not applied to AlPOs/MeAPOs systems during years, probably because the method requires starting from soluble sources, which is not common in synthesis of AlPOs and not easy to be implemented in so phase-unspecific systems. In this context, MCHA is a quite phase-specific system towards AlPO4-5/MeAPO-5 materials, and it easily directs the crystallization of these materials by changing conventional sources of Al, which are almost always insoluble solid, by the highly soluble-in-water source AlCl3•6H2O [191]. After that previous optimization, the reactants necessary to form CoAPO-5 were incorporated within the carbon matrix one by one through successive witness impregnation.…”

“…showing a pencil-like crystal emerging from the host carbon matrix. Adapted with permission from [191].…”

“…The scale bar indicates 1 µm in all cases. Adapted with permission from [191]. Copyright 2017 American Chemical Society.…”