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

Abstract

The layered zeolite precursor RUB-36, consisting of ferrierite-type layers, can be transformed into a threedimensional framework through various methods such as topotactic condensation into the CDO topology, or interlayer expansion either in the presence or absence of a silylating agent. However, the plate-like morphology of the micrometer sized crystals hampers the accessibility of the 2D micropore system, in which the channels run parallel to the plates. With the aim of introducing mesoporosity, alkaline treatments were performed on different RUB-36 derived expanded materials, and on RUB-36 itself. The effect on the physicochemical properties was examined using N 2 physisorption, PXRD, SEM and 27 Al MAS NMR while the influence on the catalytic activity was evaluated using esterification and alkylation reactions. After calcination, the purely inorganic, interlayer expanded material could be transformed into a mesopore containing FER-type material by selective removal of the interlayer T-atom followed by the recombination of the layers. In the pre-calcination state, organic moieties -originating from the silylating agent or from the organic structure directing agent (OSDA) -increase the hydrophobicity of the interlayer expanded structure and its stability against the alkaline treatment. In RUB-36, the high OSDA content limited the amount of mesopore formation through alkaline treatment. However, using the appropriate conditions, the subsequent interlayer expansion of alkaline treated RUB-36 also resulted in a mesopore containing interlayer expanded structure.

The Influence of TPOACl on the Post‐Synthesis of Hierarchical Zeolite Y and the Catalytic Cracking Application

“…However, the addition of TPOACl makes the morphology of sample DeY‐At‐TPOACl rougher. The observations of morphological changes upon alkaline treatment in presence of TPOACl are in agreement with previous reports on the protective effect of TPAOH on zeolite surfaces …”

Exfoliated Ferrierite-Related Unilamellar Nanosheets in Solution and Their Use for Preparation of Mixed Zeolite Hierarchical Structures

“… 28 − 30 The FER and CDO structures can be interconverted, which in practice is achieved before calcination by inducing lateral layer shifts (by 1/2 b ) 30 , 31 through intercalation and pH adjustment. 28 , 31 , 32 Additionally, the interlayer space between stacked fer layers can be expanded by intercalation of organic molecules, including surfactants affording d -spacing above 3 nm. 33 , 34 The applied synthesis modification, substitution of B with Al, resulted in layers with doubled layer thickness, i.e., ca.…”

“…The fer layers in ZSM-55 are related by translation and produce zeolite CDO with unidimensional eight-member-ring (MR) channels upon topotactic condensation at high temperature . The alternative stacking of fer layers, by reflection in mirror planes, produces zeolite FER with alternating 10- and 6-MR channels in cross section, and perpendicular 8-MR channels. − The FER and CDO structures can be interconverted, which in practice is achieved before calcination by inducing lateral layer shifts (by 1/2 b ) , through intercalation and pH adjustment. ,, Additionally, the interlayer space between stacked fer layers can be expanded by intercalation of organic molecules, including surfactants affording d -spacing above 3 nm. , The applied synthesis modification, substitution of B with Al, resulted in layers with doubled layer thickness, i.e., ca. 2 nm.…”

Cobalt oxide and N-doped carbon nanosheets derived from a single two-dimensional metal–organic framework precursor and their application in flexible asymmetric supercapacitors

“…[12][13][14][15][16][17][18][19][20] In particular, two-dimensional nanostructured MOFs have attracted considerable scientific and technological interest, because of their low dimensionality with unique physical and chemical properties. [21][22][23][24][25][26] However, most of the previous research work on MOF-based materials has focused only on one of the electrodes (e.g. anode for lithium ion batteries or cathode for supercapacitors), thus to assemble a full cell additional efforts are needed on a second material for the other electrode.…”