Ordered Mesoporous Alumina-Supported Metal Oxides

Abstract

The one-pot synthesis of alumina-supported metal oxides via self-assembly of a metal precursor and aluminum isopropoxide in the presence of triblock copolymer (as a structure directing agent) is described in detail for nickel oxide. The resulting mesoporous mixed metal oxides possess p6 mm hexagonal symmetry, well-developed mesoporosity, relatively high BET surface area, large pore widths, and crystalline pore walls. In comparison to pure alumina, nickel aluminum oxide samples exhibited larger mesopores and improved thermal stability. Also, long-range ordering of the aforementioned samples was observed for nickel molar percentages as high as 20%. The generality of the recipe used for the synthesis of mesoporous nickel aluminum oxide was demonstrated by preparation of other alumina-supported metal oxides such as MgO, CaO, TiO 2, and Cr 2O 3. This method represents an important step toward the facile and reproducible synthesis of ordered mesoporous alumina-supported materials for various applications where large and accessible pores with high loading of catalytically active metal oxides are needed.

Extremely high arsenic removal capacity for mesoporous aluminium magnesium oxide composites

“…1a-d. 41,42 The sizes of these hexagonally ordered mesopores are in the range of 10-15 nm. However, the mesopores in samples with higher Mg contents (from meso-50Al50Mg-400 to meso-Mg-400) are disordered and have a wormholelike structure with the network being composed of nanoparticles ( Fig.…”

“…3a). 41,42,47 18 Therefore, while the arsenic species could adsorb onto the outer surface of the samples it can also diffuse into the pore channels and bind to the inner surface of the mesopores. 48 Owing to their hexagonally ordered mesopores, the aluminium magnesium oxides with <50% Mg (from meso-Al-400 to meso70Al30Mg-400) exhibit higher surface areas (>350 m 2 g −1 ) and larger pore volumes (>0.9 cm 3 g −1 ).…”

Ordered mesoporous “one-pot” synthesized Ni-Mg(Ca)-Al2O3 as effective and remarkably stable catalysts for combined steam and dry reforming of methane (CSDRM)

“…Based on these approaches, we recently developed a mesoporous Ni-containing alumina catalyst obtained by combining 1) active phase introduction directly during the synthesis ("one-pot" synthesis allowing solid solution formation) and 2) use of an evaporation-induced self-assembly (EISA) method [47,48] in presence of a structuring agent (to obtain a mesoporous material). The resulting catalyst, with nickel nanoparticles highly dispersed and stabilized inside the structured alumina matrix, was found significantly more active and stable in long term CSDRM operation than impregnated catalysts [15].…”

Selective oxidation of allylic alcohols over highly ordered Pd/meso-Al2O3 catalysts

“…Large mesopore (10 nm -alumina has been fabricated through the use of room temperature ionic liquids as a co-solvent and template; however this material comprises randomly debundled nanofibres embedded in a wormlike porous network, and hence presents a disordered environment for the preparation of uniformly dispersed catalytic centres and reactant/product diffusion. Evaporation-induced self-assembly (EISA) utilising poly(alkylene oxide) block copolymers affords a simple route to highly ordered 2D hexagonal (p6mm) mesoporous materials [28], and has been successfully applied to synthesise ordered mesoporous aluminas with high thermal stability [29] and [30], large pores up to 7.5 nm [31], diverse transition metal dopants [32] and [33], or hierarchical architectures containing complementary macropores via colloidal crystal cotemplating with polystyrene microspheres [34].…”