Seed-directed synthesis of zincoaluminosilicate MSE-type zeolites using co-precipitated gels with tetraethylammonium hydroxide as a simple organic structure directing agent

Crystal Growth & Design

et al. 2019

Self Cite

Designing efficient synthesis methodologies, without using expensive organic structure-directing agents (OSDAs), for industrially important zeolites is of high significance not only to realize their commercialization but also to control their structural properties. Herein, we present a systematic study on seed-directed synthesis of aluminoborosilicate CON-type zeolites using tetraethylammonium hydroxide (TEAOH) as a simple OSDA, by particularly focusing on the precise size control of CIT-1 seeds, which allowed us to improve the overall production efficiency and to reach the highest solid yield of 38 wt %. It is revealed that the use of a certain amount of seeds jointly with TEAOH is the key factor governing the synthesis, where seeds act as growth centers to promote the crystallization, while TEAOH stabilizes the structure by charge-compensating with framework atoms. These findings provide insight into the synthesis of multipore structures from simple OSDA, which can be further extended to many other systems currently requiring complex OSDAs.

Section: Resultsmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 95%

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Crucial Factors for Seed-Directed Synthesis of CON-type Aluminoborosilicate Zeolites Using Tetraethylammonium

Sogukkanli

Muraoka

Crystal Growth & Design

et al. 2019

Self Cite

“…However, the use of complex OSDAs is undesirable because it generally increases the total cost of raw materials and process complexity. 13,14 Consequently, the mass production and practical applicability of many novel zeolites with unique properties have not been achieved yet.…”

Section: Introductionmentioning

confidence: 99%

“…In the 1960s, organic molecules and cations known as organic structure-directing agents (OSDAs) started to be employed to synthesize certain types of zeolites, especially those with complex pore structures or high silica composition. − OSDAs have crucial roles in directing zeolite crystallization owing to their capability to interact with zeolite frameworks, fill pores, and stabilize organic–inorganic complexes forming during crystallization. ,, Recently developed OSDAs tend to be larger and more complex, enabling them to synthesize novel zeolite structures with unique properties, such as multisize pores and large cavities. However, the use of complex OSDAs is undesirable because it generally increases the total cost of raw materials and process complexity. , Consequently, the mass production and practical applicability of many novel zeolites with unique properties have not been achieved yet.…”

Section: Introductionmentioning

confidence: 99%

Control of Competitive Structure-Directing Effect in CON-Type Zeolite Synthesis via Intermediate Addition Method

Shibuya

Crystal Growth & Design

Onozuka

et al. 2023

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The development of efficient and economical synthesis methods for CON-type aluminoborosilicate zeolite, a promising catalyst for methanol-to-olefins reactions, is in high demand. Herein, we propose the dual use of organic structure-directing agents that have different roles in the formation of CON-type zeolite. Although N,N,N-trimethyl-(−)-cis-myrtanylammonium hydroxide (TMMAOH) has a strong structure-directing effect on the formation of CON-type zeolite, it is considerably expensive. Conversely, the relatively inexpensive tetraethylammonium hydroxide (TEAOH) has a weak structure-directing effect on the formation of CON-type zeolite and/or even directs the formation of other impurity phases. The intermediate addition method of TEAOH, developed herein, could control these competitive structure-directing effects and enhance the crystallization of CON-type zeolite from economically viable raw materials. The timing of intermediate TEAOH addition was found to be a critical factor to obtain a pure CON phase, and TEA+ was occluded in the final product, suggesting the pore filler role of TEAOH, while TMMAOH is required in the early stage of crystallization.

Superior Ion‐exchange Property of Amorphous Aluminosilicates Prepared by a Co‐precipitation Method

Hikichi

Chemistry An Asian Journal

Yanaba

et al. 2020

The development of inexpensive inorganic ion‐exchangers for the purification of environmental pollutants is a social demand. Amorphous aluminosilicates with a relatively high homogeneous Al environment are prepared by a feasible co‐precipitation method, i. e., mixing an acidic aluminum sulfate solution and basic sodium silicate solution, which exhibit excellent ion‐exchange selectivity for Cs+ and Sr2+. The Kd value for Sr2+ was comparable with that of zeolite 4A. The local structures and ion‐exchange behavior of the amorphous aluminosilicates are systematically investigated. The ion‐exchange property of the amorphous aluminosilicates can be tuned by changing the interaction between the exchangeable cation and the amorphous aluminosilicates. Also, the amorphous aluminosilicates can adsorb bulky cations that zeolites hardly adsorb due to the limitation of the miropore size of zeolites.