TY - JOUR
T1 - Preparation, acid modification and catalytic activity of kaolinite nanotubes in α-pinene oxide isomerization
AU - Sidorenko, Alexander Yu
AU - Khalimonyuk, Tatiana V.
AU - Mamatkodirov, Behzodjon D.
AU - Yakubov, Yoldosh Yu
AU - Aho, Atte
AU - Sviridova, Tatiana V.
AU - Kouznetsova, Tatiana F.
AU - Adizov, Bobirjon Z.
AU - Ibragimov, Aziz B.
AU - Murzin, Dmitry Yu
AU - Gu, Yanlong
AU - Agabekov, Vladimir E.
N1 - Publisher Copyright:
© 2024 The Royal Society of Chemistry.
PY - 2024/8/16
Y1 - 2024/8/16
N2 - 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 (H2SO4-H2O2), 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 m2 g−1), pore volume by 1.5 times (0.23 cm3 g−1) and acidity by 4.1 times (49 μmol g−1). 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 trans-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 per se 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.
AB - 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 (H2SO4-H2O2), 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 m2 g−1), pore volume by 1.5 times (0.23 cm3 g−1) and acidity by 4.1 times (49 μmol g−1). 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 trans-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 per se 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.
UR - http://www.scopus.com/inward/record.url?scp=85201689447&partnerID=8YFLogxK
U2 - 10.1039/d4ra03777d
DO - 10.1039/d4ra03777d
M3 - Article
AN - SCOPUS:85201689447
SN - 2046-2069
VL - 14
SP - 25079
EP - 25092
JO - RSC Advances
JF - RSC Advances
IS - 34
ER -