Synthetic and Catalytic Potential of Amorphous Mesoporous Aluminosilicates Prepared by Postsynthetic Aluminations of Silica in Aqueous Media

authors	Locus, R; Verboekend, D; d'Halluin, M; Dusselier, M; Liao, YH; Nuttens, N; Jaumann, T; Oswald, S; Mafra, L; Giebeler, L; Sels, B
nationality	International
journal	CHEMCATCHEM
author keywords	acidity; aluminosilicates; aluminum; mesoporous materials; solid-state structures
keywords	POST-SYNTHESIS ALUMINATION; FRAMEWORK ALUMINUM CONTENT; SOLID ACID CATALYSTS; LACTIC-ACID; MCM-41; ZEOLITE; ABSORPTION; CONVERSION; DESIGN; SBA-15
abstract	Amorphous aluminosilicate catalysts have been used industrially on a large scale for almost a century. However, the influence of the pH on the alumination of silica in aqueous solutions has remained largely unclear. Herein, room temperature aluminations of different mesoporous amorphous silicas (fumed silica, dried silica gel, SBA-15, MCM-41, and COK-12) with aqueous solutions of various pH (3-13) are explored. The aqueous solutions are prepared using different aluminum sources (Al(NO3)(3) or NaAlO2) and alkaline additives (NaOH or NH4OH). The decoupling of pH and Al source using alkaline additives results in a vast experimental potential to prepare unique aluminosilicates, whereby an important role is played by the pH development during the treatment. The bulk and surface composition, acidity, aluminum coordination, morphology, hydrothermal stability, and porosity of the obtained materials are characterized. Optimal samples possess large surface areas and superior acidities (up to 50% higher) and outstanding stabilities compared to aluminosilicates prepared with state-of-the-art methods. The obtained materials are evaluated in a series of acid-catalyzed model reactions involving substrates of various chemical reactivity and size, enabling insight in the catalytic functionality of the introduced BrOnsted and Lewis sites. The potential of the obtained materials is emphasized by the similar or superior acidity and catalytic performance compared to several benchmark industrial silica-alumina-based catalysts.
publisher	WILEY-V C H VERLAG GMBH
issn	1867-3880
year published	2018
volume	10
issue	6
beginning page	1385
ending page	1397
digital object identifier (doi)	10.1002/cctc.201701660
web of science category	Chemistry, Physical
subject category	Chemistry
unique article identifier	WOS:000428375400024