A simple method based on the characterization (composition, Bronsted and Lewis acidities) of acid treated HBEA zeolites was developed for estimating the concentrations of framework, extraframework and defect Al species.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1039/b409964h | DOI Listing |
Inorg Chem
December 2024
Department of Geological Sciences, Pusan National University, Busan 46241, Korea.
Synthetic mordenite is widely used as a molecular sieve, adsorbent, and catalyst. To enhance these functionalities, it is crucial to understand the ion-exchange properties and cation-exchange sites of the zeolite. In this study, we analyzed the structural changes in fully Cs-, Sr-, Cd-, and Pb-exchanged mordenite by using synchrotron X-ray powder diffraction under ambient conditions.
View Article and Find Full Text PDFInorg Chem
December 2024
School of Materials Science and Engineering, Tongji University, Shanghai 201804, China.
Luminescent silver clusters that are confined inside porous zeolites have attracted great research interest due to the combined advantages of high quantum yield, tunable emission, excellent chemical stability, and desirable adoption ability of this micronano-composite. In this research, a series of Ag-exchanged R-LTA/Ag (R = Li, Na, K) zeolites were synthesized, in which the silver clusters showed blue-shifted excitation in the UV region, red-shifted emission in the visible region, and decreased emission intensity when taking Li, Na, and K as the extra-framework cations, respectively. The [Ag(HO)R-sod] ( = 2, 4; R = Li, Na, K) structures were constructed, and the TD-DFT method was further carried out to study the influence of extra-framework cations on the luminescence performance of [Ag] clusters, in which the substitution of Al for Si and the reasonable hydrate levels were both taken into consideration.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2024
Key Laboratory of Advanced Energy Materials Chemistry of Ministry of Education, College of Chemistry, Nankai University, Tianjin, 300071, P.R. China.
The adsorptive separation of molecules with very similar physical properties is always a challenging task. Reported herein is the design and tailoring of zeolite adsorbent for the precise discrimination and separation of CO-CH mixture through the pronounced trapdoor effect. Typically, Sr exchanged K-type clinoptilolite, namely Sr/K-HEU, is developed as a robust zeolite adsorbent for inverse CO-CH separation, showing the-state-of-the-art dynamic CO/CH selectivity of 48.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2024
Department of Chemistry and Catalysis Research Center, Technical University of Munich, Lichtenbergstraße 4, 85748, Garching, Germany.
Combining operando X-ray absorption spectroscopy (XAS) and computational modelling shows unequivocally the distribution of active species in fresh and hydrothermally aged Cu-CHA and Cu-AEI zeolites during NH-assisted selective catalytic reduction of NO. Four principal species co-exist: (i) Cu cations coordinated to NH, (ii) Cu cations coordinated to the zeolite framework, (iii) solvated Cu cations, and (iv) framework-coordinated Cu species (Cu ) formed upon hydrothermal ageing of the zeolite sample. The Cu species were only observed in the hydrothermally aged zeolite samples and are formed upon the interaction of hydrated Cu cations with extra-framework Al (EFAl) generated during the hydrothermal treatment.
View Article and Find Full Text PDFSci Rep
October 2024
Department of Pure and Applied Sciences, University of Urbino Carlo Bo, 61029, Urbino, Italy.
The sorption properties of zeolites are controlled by several factors, i.e. Si/Al ratio of the aluminosilicate framework [AlSiO], the type and position of the extraframework (EF) cations, and the applied temperature.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!