Highly Mesoporous Single-Crystalline Zeolite Beta Synthesized Using a Nonsurfactant Cationic Polymer as a Dual-Function Template

Abstract

Mesoporous zeolites are useful solid catalysts for conversion of bulky molecules because they offer fast mass transfer along with size and shape selectivity. We report here the successful synthesis of mesoporous aluminosilicate zeolite Beta from a commercial cationic polymer that acts as a dual-function template to generate zeolitic micropores and mesopores simultaneously. This is the first demonstration of a single nonsurfactant polymer acting as such a template. Using high-resolution electron microscopy and tomography, we discovered that the resulting material (Beta-MS) has abundant and highly interconnected mesopores. More importantly, we demonstrated using a three-dimensional electron diffraction technique that each Beta-MS particle is a single crystal, whereas most previously reported mesoporous zeolites are comprised of nanosized zeolitic grains with random orientations. The use of nonsurfactant templates is essential to gaining single-crystalline mesoporous zeolites. The single-crystalline nature endows Beta-MS with better hydrothermal stability compared with surfactant-derived mesoporous zeolite Beta. Beta-MS also exhibited remarkably higher catalytic activity than did conventional zeolite Beta in acid-catalyzed reactions involving large molecules.

Investigating the Influence of Mesoporosity in Zeolite Beta on Its Catalytic Performance for the Conversion of Methanol to Hydrocarbons

“…For example, we recently reported that a non-surfactant cationic polymer can act as a dual template to synthesize hierarchical zeolite Beta. 28 The obtained material (Beta-MS) featured remarkable mesoporosity, single crystallinity, excellent stability, and superior catalytic activity over conventional zeolite Beta in several liquid-phase reactions. Although there is a bulk of evidence for the superior catalytic properties of hierarchical zeolites, a systematic 4 comparison between a hierarchical zeolite and its bulk (non-mesoporous) counterpart for a particular reaction on the basis of detailed catalyst characterization and a careful analysis of the full products is lacking.…”

A solvent evaporation route towards fabrication of hierarchically porous ZSM-11 with highly accessible mesopores

“…Hard template route using carbon blacks 8 , soft template using organosilanes 9 , cationic polymers 10 , bifunctional structure directing agent 11 , as well as postsynthetic desilication 12 routes have been established. Several merits stems from prompted mass transport for instance, high activity, occasional high primary product selectivity, improved large molecule accessibility, as well as longer lifetimes, have been achieved by replacing conventional zeolites with HPZs 13 .…”

Ni nanoparticles encapsulated into mesoporous single-crystalline HBEA: application for drainage oil hydrodeoxygenation to diesel

“…The acid sites were probed by IR spectroscopy of adsorbed pyridine (Fig. [13] The B-MS sample had a high external surface area (399 m 2 ·g -1 ). The results revealed that the Brønsted acid site of B-MS was 0.09 mmol·g -1 , which was lower than that of B-20 (0.20 mmol·g -1 ) and B-26 (0.18mmol·g -1 ).…”