Multifunctional Hybrid Organic−Inorganic Catalytic Materials with a Hierarchical System of Well-Defined Micro- and Mesopores

Abstract

Novel layered zeolitic organic−inorganic materials (MWW-BTEB) have been synthesized by intercalation and stabilization of arylic silsesquioxane molecules between inorganic zeolitic MWW layers. The organic linkers are conformed by two condensed silyl-arylic groups from disilane molecules, such as 1,4-bis(triethoxysilyl)benzene (BTEB), which react with the external silanol groups of the zeolitic layers. The hybrids contain micropores within the inorganic layers and a well-defined mesoporous system in between the organic linkers. An amination post-treatment introduces basic groups in the organic linkers close to the acid sites present in the structural inorganic counterpart. Through this methodology it has been possible to prepare bifunctional acid−base catalysts where the acid sites are of zeolitic nature located in the inorganic building blocks and the basic sites are part of the organic structure. The resultant materials can act as bifunctional catalysts for performing a two-step cascade reaction that involves the catalytic conversion of benzaldehyde dimethylacetal into benzylidene malononitrile.

Selective aerobic oxidation of activated alkanes with MOFs and their use for epoxidation of olefins with oxygen in a tandem reaction

“…There is much interest in the design of hybrid materials for selective and multi-step catalytic processes 1 . In this field, Metal-Organic Frameworks (MOFs) can play an important role due to the possibility to control and fine tune the crystalline structure, porosity, chemical environment and functionalities of the material.…”

MOFs as multifunctional catalysts: One-pot synthesis of menthol from citronellal over a bifunctional MIL-101 catalyst

“…For this reaction, the acid-base pairs work in a concerted way to activate simultaneously the two reactants, as was previously shown with other inorganic and organic catalysts with acid-base pairs. [15][16][17][18] . Similarly, Wu et al 13 prepared a lanthanide MOF containing Lewis acid Tb 3+ and Lewis base triphenylamine sites, and used it for Knoevenagel an cyanosylalation reactions.…”

Synthesis of high quality alkyl naphthenic kerosene by reacting an oil refinery with a biomass refinery stream

“…38 It has been reported that the alkylation mainly occurs on the external surface of MWW and because of that a new type of 2D layered zeolite with well structured and very large external surface area were developed by delamination of a laminar precursors of different zeolites. 39,40,41 In the case of the laminar precursor of MWW, the 2D layered zeolite ITQ-2 was prepared in where the 12R hemicavities similar to cups are exposed to the exterior ready to adsorb-react-desorb without requiring diffusion through micropores 42 (see Figure 12 and Figure 1 Supporting information). Since this material with external surface areas larger than 600 m 2 /g was shown to be more active for alkylation of biphenyl with propene than the corresponding 3D MWW zeolite, 43 we have studied here, the catalytic behavior of ITQ-2 for alkylation of toluene with HMF.…”