# Regulation of the Properties of the Hierarchical Porous Structure of Alumophosphate Molecular Sieves AEL by Reaction Gels Prepared with Different Templates

## TL;DR

This study explores how different templates affect the structure and properties of alumophosphate molecular sieves, improving their performance in adsorption and catalysis.

## Contribution

The paper introduces a method to synthesize hierarchical AlPO4-11 with enhanced mesopore volume using specific templates.

## Key findings

- Reaction gels with DPA, DIPA, and DBA form amorphous xerogels of 5–10 nm nanoparticles.
- Using DEA results in a combination of layered and amorphous aluminophosphate phases.
- Template choice significantly affects the porous structure and nanocrystal size of AlPO4-11.

## Abstract

Microporous alumophosphate molecular sieves AlPO4-n are promising materials for use in catalysis, gas adsorption, and gas separation. However, AlPO4-n faces problems such as diffusion limitations that lead to a deterioration in mass transfer. To solve this problem, we studied the crystallization of alumophosphate reaction gels prepared using aluminum isopropoxide and various secondary amines as templates, including diethyl-, di-n-propyl-, diisopropyl-, and di-n-butylamines. Using X-ray diffraction, Ramon spectroscopy, and STEM methods, it has been demonstrated that the reaction gels prepared using DPA, DIPA, and DBA are amorphous xerogels consisting of 5–10 nm nanoparticles. The reaction gel prepared with DEA is a combination of a layered phase and an amorphous aluminophosphate. It has been shown that the use of aluminum iso-propoxide allows the production of AlPO4-11 in the form of 2–4 µm aggregates consisting of primary AlPO4-11 nanocrystals. The template was found to exert a significant effect upon both the characteristics of the porous structure and the size of AlPO-11 nanocrystals. A template is proposed for the synthesis of hierarchical AlPO4-11 with a maximum volume of mesopores. The morphology and crystal size of AlPO4-11 were found to strongly influence its adsorption properties in the adsorption of octane.