Sidorenko Alexander Yu, Khalimonyuk Tatiana V, Mamatkodirov Behzodjon D, Yakubov Yoldosh Yu, Aho Atte, Sviridova Tatiana V, Kouznetsova Tatiana F, Adizov Bobirjon Z, Ibragimov Aziz B, Murzin Dmitry Yu, Gu Yanlong, Agabekov Vladimir E
Institute of Chemistry of New Materials of National Academy of Sciences of Belarus 220084, Skaryna str, 36 220141 Minsk Belarus
Institute of General and Inorganic Chemistry of the Academy of Sciences of the Republic of Uzbekistan 100170, Mirzo-Ulugbek str., 77-a Tashkent Uzbekistan.
RSC Adv. 2024 Aug 16;14(34):25079-25092. doi: 10.1039/d4ra03777d. eCollection 2024 Aug 5.
In this work kaolinite nanotubes (KNT) were obtained from commercial kaolin AKF-78 (Uzbekistan) by starting material sequential intercalation by DMSO and methanol, followed by treatment with a cetyltrimethylammonium chloride solution. Acid functionalization of KNT for catalytic applications was successfully performed for the first time using a two-step treatment with piranha solution (HSO-HO), which resulted in the removal of organic impurities as synthetic artifacts and an increase in specific surface area by 3.9 times (up to 159 m g), pore volume by 1.5 times (0.23 cm g) and acidity by 4.1 times (49 μmol g). The values of the porous structure parameters and concentration of acid sites in processed kaolinite nanotubes practically corresponded to those for natural halloysite nanotubes (HNT) modified in the same way. Both types of materials demonstrated catalytic activity in the model reaction of α-pinene oxide isomerization in various solvents, including green ones, with selectivity to -carveol up to 55-57% and campholenic aldehyde of 50-51%, depending on the medium used. A satisfactory correlation between solvent polarity and selectivity was also observed. To the best of our knowledge, this is the first example of using modified kaolinite nanotubes as a catalyst. Overall, treatment of KNT with piranha solution provides not only catalytic activity but also the opportunity for further functionalization and application of these nanomaterials.
在本工作中，通过用二甲基亚砜（DMSO）和甲醇对商业高岭土AKF - 78（乌兹别克斯坦）进行原料顺序插层，随后用十六烷基三甲基氯化铵溶液处理，得到了高岭石纳米管（KNT）。首次成功地使用王水（H₂SO₄ - H₂O₂）两步处理法对用于催化应用的KNT进行了酸功能化，这导致作为合成假象的有机杂质被去除，比表面积增加了3.9倍（达到159 m²/g），孔体积增加了1.5倍（0.23 cm³/g），酸度增加了4.1倍（49 μmol/g）。处理后的高岭石纳米管的多孔结构参数值和酸位点浓度实际上与以相同方式改性的天然埃洛石纳米管（HNT）的值相当。在各种溶剂（包括绿色溶剂）中的α - 蒎烯氧化物异构化模型反应中，这两种材料都表现出催化活性，根据所用介质的不同，对香芹醇的选择性高达55 - 57%，对龙脑烯醛的选择性为50 - 51%。还观察到溶剂极性与选择性之间存在令人满意的相关性。据我们所知，这是使用改性高岭石纳米管作为催化剂的首个实例。总体而言，用王水处理KNT不仅提供了催化活性，还为这些纳米材料的进一步功能化和应用提供了机会。
