摘要：The in situ synthesis of mesoporous nanotubes from natural minerals remains a great challenge. Herein, we report the successful synthesis of mesoporous silica nanotubes （MNTs） with a varying inner-shell thickness and a preserved clay outer shell from natural-halloysite nanotubes （HNTs）. After the enlargement of the lumen diameter of the tubular aluminosilicate clay by acid leaching, uniform mesopores were introduced by a modified pseudomorphic transformation approach, while the clay outer shell was well-preserved. Using density functional theory calculations, the atomic structure evolution and the energetics during A1 leaching and Si-OH condensation were studied in detail. After the leaching of A1 ions from the HNTs, local structural changes from Al（Oh） to A1（V） at a medium leaching level and to AI（Td） at a high leaching level were confirmed. The calculated hydroxylation energy of two kinds of silica components in the acid-leached HNTs （the distorted two-dimensional silica source in the inner shell and the intact aluminosilicate structure in the outer shell） was 0.5 eV lower or 1.0 eV higher than that of bulk silica, which clarifies the different behavior of the silica components in the hydrothermal process. The successful synthesis of reactive MNTs from HNTs introduces a new strategy for the synthesis of mesoporous nanocontainers with a special morphology using natural minerals. In particular, MNT samples with numerous reactive AI（V） species and a specific surface area up to 583 m^2/g （increased by a factor of 10） are promising drugloading nanocontainers and nanoreactors.

摘要：Encapsulating noble metal nanoparticles(NPs)within the zeolite framework enhances the stability and accessibility of active sites;however,direct synthesis remains a challenge because of the easy precipitation of noble metal species under strong alkali crystallization ***,beta zeolite-encapsulated Pt NPs(Pt@Beta)were synthesized via a hydrothermal approach involving an unusual acid hydrolysis preaging *** ligand—(3-mercaptopropyl)trimethoxysilane—and Pt precursor were cohydrolyzed and cocondensed with a silica source in an initially weak acidic environment to prevent colloidal precipitation by enhancing the interaction between the Pt and silica ***,the resultant 0.2%Pt@Beta was highly active in the transformation of 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid(FDCA)under atmospheric O2 conditions by using water as the solvent while stably evincing a high yield(90%)associated with a large turnover number of *** excellent catalysis behavior is attributable to the enhanced stability that inhibits Pt leaching and strengthens the intermediates that accelerate the rate-determining step for the oxidation of 5-formyl-2-furan carboxylic acid into FDCA.

摘要：Among the reactions catalyzed by zeolites there are some that exhibit high selectivity due to the spatial confinement effect of the zeolite *** the acidity,particularly the distribution and location of the Bronsted acid sites in the zeolite is effective for making it a better catalyst for these *** prepared a series of H-mordenite（H-MOR） samples by varying the composition of the sol-gel,using different structure directing agents and ***3-TPD and IR characterization of adsorbed pyridine were employed to determine the amount of Bronsted acid sites in the 8-membered ring and 12-membered ring *** was shown that controlled synthesis was a promising approach to improve the concentration of Bronsted acid sites in MOR,even with a low Al *** an appropriate composition of Si and Al in the sol-gel favored a higher proportion of Bronsted acid sites in the 8-membered ring *** as a structure-direct agent gave an obvious enrichment of Bronsted acid sites in the 8-membered *** of dimethyl ether was used as a probe reaction to examine the modification of the acid properties,especially the Bronsted acid sites in the 8-membered ring *** was a linear relationship between methyl acetate formation and the number of Bronsted acid sites in the 8-membered ring channels,demonstrating the successful modification of acid *** results provide information for the rational design and modification of zeolites with spatial constraints.