Shape-selective organic–inorganic zeolitic catalysts prepared via interlayer expansion

Abstract

Interlayer expansion of layered zeolite precursors is achieved via the insertion of an additional Tatom in between the layers, typically by means of a silylating agent as source of the T-atom. (3mercaptopropyl)methyldimethoxysilane was used as Si-source in the interlayer expansion of the layered zeolite precursors RUB-36 and RUB-39. The structure expansion was confirmed with PXRD. The incorporation of the silylating agent was followed with 29 Si MAS NMR, 13 C CP MAS NMR and thermogravimetric analysis. The incorporated thiol groups were oxidized with H2O2 to obtain sulphonic acid groups in between the layers. 13 C CP MAS NMR was used to characterize the organic species and monitor the conversion of thiol to propylsulphonic groups. The shapeselective properties of the obtained materials were investigated in acid-catalyzed tetrahydropyranylation reactions.

From Layered Zeolite Precursors to Zeolites with a Three-Dimensional Porosity: Textural and Structural Modifications through Alkaline Treatment

“…In Al-COE-3 obtained using only H 2 SO 4 , there are no methyl groups on the bridging Si atoms. The increased stability should therefore be attributed to the presence of residual OSDA, which is not always fully removed during the interlayer expansion treatment, and which seems to increase the hydrophobicity of the material, and hence its resilience to aqueous base. The same effect could add to the stability of Al-COE-3 obtained from DCDMS and HCl synthesis.…”

“…The removal of this newly incorporated Al upon interlayer expansion implies the loss of potential catalytically active sites. However, alternative interlayer expansion methods using more complex silylating agents or incorporating different heteroatoms have been proposed before to introduce catalytic activity. , Combining this alkaline treatment with those interlayer expansion methods could offer new ways for obtaining hierarchical catalysts from RUB-36. The total mesopore volume and external surface area obtained in this modification may still be rather low in comparison to other topologies, but this is likely related to the crystal morphology.…”

Synthesis of the RTH-type layer: the first small-pore, two dimensional layered zeolite precursor

“…Recently, it has also been shown to be possible to introduce catalytic activity in the pillars. 32 , 33 Excellent reviews of the above strategies are available. 8 , 9 …”

“…Recently, it has also been shown to be possible to introduce catalytic activity in the pillars. 32,33 Excellent reviews of the above strategies are available. 8,9 All of the previously reported layered zeolite precursors are dense layers, that is, they contain no pores (8-membered ring (MR) or larger) that are perpendicular to the layers.…”

Advances in the Synthesis of Crystalline Metallosilicate Zeolites via Interlayer Expansion

“…The IEZ material has larger pores than the 3D structure obtained by direct calcination and is expected to offer better catalytic activity [ 97 , 98 , 99 , 100 , 101 ]. Table 6 exhibits catalytic activity and selectivity in oxidation of cyclohexene over titanosilicates.…”