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首页> 外文期刊>RSC Advances >The hypersaline synthesis of titania: from powders to aerogels
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The hypersaline synthesis of titania: from powders to aerogels

机译：二氧化钛的高盐合成：从粉末到气凝胶

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High surface area mesoporous titania has been synthesized using ordinary salts (chlorides) for morphology control during the sol-gel process. Applying Ti-alkoxide (TTIP) as a titania precursor and a highly-concentrated hypersaline medium, different results have been obtained according to the dispersing medium selected. By working in an acid environment, the hypersaline medium controls the oxide network growth, since different salts (and different salts amount) influence the surface area, porosity, crystallinity and polymorphs rearrangement of the final material, favoring the formation of acicular-like rutile at mild conditions. Nevertheless, it has been verified that, according to the Hofmeister series, salting-in ions induce an increase in the titania surface area, going from 79 (for the reference, without any salts) up to 253 m(2) g(-1) (for the Li-templated titania). By working in alcoholic media, the hypersaline environment favors the gelification process and the formation of amorphous titania aerogels or highly-porous monoliths, according to the drying conditions selected (respectively supercritical CO2 or ambient pressure air drying). Two different alcoholic media (ethanol and 2-propanol) have been compared. Such salt-templated titania aerogels are mesoporous (with BET surface area comprised between 322 and 490 m(2) g(-1)). Besides the surface area, even the pore volume and the pore size can be controlled by both the reaction medium and the drying step: in particular, air-dried monoliths are small mesoporous (BET surface area between 419 and 518 m(2) g(-1)). Reference materials synthesized in alcoholic media without using any salts do not gelify (thus confirming the importance of the hypersaline medium), whereas titania particles precipitate, inducing aggregation into small mesoporous powders. In general, the hypersaline-mediated titania production seems to be an interesting chemical toolbox, sustainable, highly efficient and also potentially suitable for industrial scaling-up.
机译：在溶胶-凝胶过程中，已使用普通盐（氯化物）合成了高表面积的中孔二氧化钛，用于形态控制。将钛醇盐（TTIP）用作二氧化钛的前体和高浓度的高盐度介质，根据所选的分散介质获得了不同的结果。通过在酸性环境中工作，高盐介质控制了氧化物网络的生长，因为不同的盐（和不同的盐量）会影响最终材料的表面积，孔隙率，结晶度和多晶型物重排，从而有利于形成针状金红石温和的条件。但是，已经证实，根据霍夫迈斯特系列，盐分离子会引起二氧化钛表面积的增加，从79（仅供参考，不含任何盐）增加到253 m（2）g（-1） ）（用于Li模板的二氧化钛）。通过在酒精介质中工作，根据选择的干燥条件（分别为超临界CO2或环境压力空气干燥），高盐环境有利于胶凝过程以及无定形二氧化钛气凝胶或高多孔性整料的形成。比较了两种不同的酒精介质（乙醇和2-丙醇）。这种盐模板的二氧化钛气凝胶是中孔的（BET表面积介于322和490 m（2）g（-1）之间）。除了表面积外，反应介质和干燥步骤都可以控制孔体积和孔径：特别是风干的整料小中孔（BET表面积在419和518 m（2）g（ -1））。在不含任何盐的酒精介质中合成的参考物质不会胶凝（从而证实了高盐介质的重要性），而二氧化钛颗粒会沉淀，从而导致聚集成小的中孔粉末。总的来说，高盐介导的二氧化钛生产似乎是一个有趣的化学工具箱，可持续，高效并且还可能适合工业规模化生产。

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