Exploring Hydrothermal Synthesis of SAPO-18 under High Hydrostatic Pressure.

Raquel Simancas,Hiroyuki Shibata,Anand Chokkalingam,Yasuo Yonezawa,Mariko Ando,Kenta Iyoki,Masamori Takemura,Toru Wakihara,Sohei Sukenaga,Tatsuya Okubo

doi:10.3390/nano12030396

Raquel Simancas, Hiroyuki Shibata + Show 8 more

Open Access

https://doi.org/10.3390/nano12030396

Copy DOI

Abstract

The effect of external hydrostatic pressure on the hydrothermal synthesis of the microporous silicoaluminophosphate SAPO-18 has been explored. The crystallization of the SAPO-18 phase is inhibited at 150 °C under high pressures (200 MPa) when using relatively diluted synthesis mixtures. On the contrary, the use of concentrated synthesis mixtures allowed SAPO-18 to be obtained in all the studied conditions. The obtained solids were characterized with XRD, SEM, ICP-AES, TG and 27Al and 31P MAS NMR spectroscopy. The results highlight the importance of the external pressure effect on the hydrothermal synthesis of molecular sieves and its influence on the interaction between the organic molecule and the silicoaluminophosphate network.

Highlights

Introduction and Zhendong LiuZeolites and related materials have been used in a wide range of applications as ion exchangers, adsorbents and catalysts [1,2,3]
Many of these aluminophosphate structures are included in the Database of Zeolite Framework Types approved by the Structure Commission of the International Zeolite Association (IZA-SC) [6]
AlPO and SAPO materials are usually synthesized by the hydrothermal treatment of an aqueous mixture containing organic molecules, such as amines, alkyl ammonium cations and alkanolamines such as Organic Structure-Directing Agents (OSDAs) [9,11,12]

Summary

Introduction

Zeolites and related materials have been used in a wide range of applications as ion exchangers, adsorbents and catalysts [1,2,3]. Until more than 300 open-framework aluminophosphate structures were published in the literature by 2020 [5]. The substitution of part of the P atoms by Si atoms introduces Brønsted acidity in the materials and expands the catalytic applications of the obtained silicoaluminophosphates (SAPOs) [7,8,9,10]. AlPO and SAPO materials are usually synthesized by the hydrothermal treatment of an aqueous mixture containing organic molecules, such as amines, alkyl ammonium cations and alkanolamines such as Organic Structure-Directing Agents (OSDAs) [9,11,12]

Methods

Results

Conclusion