ZSM-5 Zeolite Single Crystals with b-Axis-Aligned Mesoporous Channels as an Efficient Catalyst for Conversion of Bulky Organic Molecules

Abstract

The relatively small and sole micropores in zeolite catalysts strongly influence the mass transfer and catalytic conversion of bulky molecules. We report here aluminosilicate zeolite ZSM-5 single crystals with b-axis-aligned mesopores, synthesized using a designed cationicamphiphilic copolymer as a mesoscale template. This sample exhibits excellent hydrothermal stability. The orientation of the mesopores was confirmed by scanning and transmission electron microscopy. More importantly, the b-axis-aligned mesoporous ZSM-5 shows much higher catalytic activities for bulky substrate conversion than conventional ZSM-5 and ZSM-5 with randomly oriented mesopores. The combination of good hydrothermal stability with high activities is important for design of novel zeolite catalysts. The b-axis-aligned mesoporous ZSM-5 reported here shows great potential for industrial applications.

π–π interaction of aromatic groups in amphiphilic molecules directing for single-crystalline mesostructured zeolite nanosheets

“…Here, we rationally designed a series of bolaform amphiphilic molecules with bi-quaternary ammonium head groups and biphenyl groups (BC Ph-n-6-6 ), which could act as particular cationic dimers, to direct a new type of hierarchical SCZN with uniform mesopore size due to the presence of their hydrophobic parts (we denoted these samples as SCZN-2). Figure 2 shows the XRD patterns of the as-made SCZNs synthesized with BC Ph-n-6-6 (n ¼ 4, 6,8,10,12). All samples show ordered lamellar structures.…”

“…There are several methods to prepare hierarchical zeolites such as top-down desilication by alkali post-synthetic modification 5 , bottom-up directed assembly by self-assembly of various zeolite seeds 6 and by templates. Much attention has been focused on the synthesis of zeolites with desired pore structure using soft and hard templates, such as surfactants [7][8][9] , cationic polymer 10 , polystyrene beads 11 , mesoporous silica 12 and carbon materials [13][14][15] . Although much considerable progress has been made in developing strategies to direct the formation of porous zeolites, designing a templating strategy for obtaining ordered hierarchical pore structures with crystallographically ordered zeolite remains an unsolved challenge.…”

Zeolite with oriented arrays of macrochannels from zeolitic building block disassembly

“…These materials also hold promise for advanced applications such as medicines [9], photonics [10,11], photoelectronics [12,13], and other emerging nanotechnologies [14]. The zeolites with ordered as well as oriented mesopores have been successfully prepared from direct assembly by structure-directing agents (SDAs) [15][16][17][18][19][20][21][22][23][24]. However, the sacrificial templating approach is limited when applied to forming the macropores in zeolite crystals due to the phase separation between the macroporous materials and zeolites in the hydrothermal syntheses, resulting in the formation of intercrystalline macropores [25][26][27][28][29].…”

One-pot pseudomorphic crystallization of mesoporous porous silica to hierarchical porous zeolites

“…The surfactant or polymer generating the mesopore and small structure-directing agent (SDAs) leading to the micropore in the crystalline zeolite framework must work in a cooperative rather than a competitive manner in order to avoid the formation of the physical mixtures of amorphous mesoporous material and bulky zeolite, when dual templates were used [16][17][18][19][20].…”