Importance of the Order of Addition of the Alumina Precursor and its Type Into Al-SBA-15 Mesoporous Materials for Use as Water Adsorbents

In the present report, Al-SBA mesoporous materials were investigated for use as water adsorbents. Different precursors for aluminum were investigated: aluminum sulfate and nitrate, boehmite, and aluminum tri-sec-butoxide. Furthermore, three different procedures for addition of the silica and alumina sources were tested. Samples were characterized by nitrogen adsorption to observe their textural characteristics and by thermogravimetric desorption of water to address their performance. The sample synthesized with aluminum tri-sec-butoxide as aluminum precursor and a pre-hydrolysis step of the silica source presented the highest adsorption capacity: 1057 g.kg-1. It was also observed that water attaches more strongly to Al-containing samples than to pure silica, and that water adsorption capacity is more related to the pore volume of samples than to their surface area. This work has shown that functionalizing SBA-15 materials with aluminum is a promising strategy for producing water adsorbents with improved performance and potential for many applications.

本研究报告中，我们针对用作水体吸附剂的Al-SBA介孔材料（Al-SBA mesoporous materials）开展了相关研究。本次研究考察了多种铝前驱体，包括硫酸铝、硝酸铝、勃姆石以及三仲丁氧基铝。此外，还测试了三种不同的硅源与铝源添加工艺。通过氮气吸附法表征样品的织构特性，并借助水的热重脱附实验评估其吸附性能。以三仲丁氧基铝作为铝前驱体、并对硅源实施预水解步骤合成的样品，展现出最高的水吸附容量：1057 g·kg⁻¹。研究同时观测到，相较于纯硅基样品，含铝样品对水分子的结合强度更高；且样品的水吸附容量与其孔体积的相关性显著高于其比表面积。本研究表明，采用铝对SBA-15材料进行功能化，是制备性能优异、具备多领域应用潜力的水体吸附剂的极具前景的策略。