A Facile Strategy To Design Zeolite L Crystals with Tunable Morphology and Surface Architecture

Abstract

Tailoring the anisotropic growth rates of materials to achieve desired structural outcomes is a pervasive challenge in synthetic crystallization. Here we discuss a method to selectively control the growth of zeolite crystals, which are used extensively in a wide range of industrial applications. This facile method cooperatively tunes crystal properties, such as morphology and surface architecture, through the use of inexpensive, commercially available chemicals with specificity for binding to crystallographic surfaces and mediating anisotropic growth. We examined over 30 molecules as potential zeolite growth modifiers (ZGMs) of zeolite L (LTL type) crystallization. ZGM efficacy was quantified through a combination of macroscopic (bulk) and microscopic (surface) investigations that identified modifiers capable of dramatically altering the cylindrical morphology of LTL crystals. We demonstrate an ability to tailor properties critical to zeolite performance, such as external porous surface area, crystal shape, and pore length, which can enhance sorbate accessibility to LTL pores, tune the supramolecular organization of guest-host composites, and minimize the diffusion path length, respectively. We report that a synergistic combination of ZGMs and the judicious adjustment of synthesis parameters produce LTL crystals with unique surface features, and a range of length-to-diameter aspect ratios spanning 3 orders of magnitude. A systematic examination of different ZGM structures and molecular compositions (i.e., hydrophobicity and binding moieties) reveal interesting physicochemical properties governing their efficacy and specificity. Results of this study suggest this versatile strategy may prove applicable for a host of framework types to produce unrivaled materials that have eluded more conventional techniques.

Lewis Acid Zeolites for Biomass Conversion: Perspectives and Challenges on Reactivity, Synthesis, and Stability

“…Often it is desirable to tune crystal size or introduce mesoporosity in Lewis acid zeolites to allow better diffusion to and from active sites and decrease the chance of pore blockage owing to deposition of side products. To this end, Rimer et al (30,31) have shown that zeolite growth modifiers are capable of modulating zeolite crystal structure. Ouyang et al (32) show that delaminated Sn-DZ-1, an MWW framework material with Sn postsynthetically incorporated into surface-accessible sites, has higher activity for the BV oxidation of 5-bromo-2-adamontanone with H 2 O 2 than Sn-Beta.…”

Unraveling the non-classic crystallization of SAPO-34 in a dry gel system towards controlling meso-structure with the assistance of growth inhibitor: Growth mechanism, hierarchical structure control and catalytic properties

“…A suggested molecular sieve growth inhibitor 1,2,3-hexanetriol is deliberately selected to achieve crystallization process modification. The inhibitor was previously suggested by Rimer et al [50] to tailor the morphology of zeolite L for its strong interaction with zeolite surfaces. SAPO-34 with two different Si contents have been synthesized via the above proposed route, together with hydrothermally derived conventional ones for comparison.…”

Specificity of Growth Inhibitors and their Cooperative Effects in Calcium Oxalate Monohydrate Crystallization

“…9−11 It is important to emphasize that inhibitor−crystal interactions are not restricted to biological systems, but are also evident in synthetic crystallization. Notable examples include modifiers of organic crystals, 12,13 zeolites, 14,15 minerals, 16−19 and metal oxides. 20 In this study we focus on growth inhibition of calcium oxalate monohydrate (COM), which is the primary constituent of human kidney stones.…”