Desilication of ZSM-5 and ZSM-12 zeolites : impact on textural, acidic and catalytic properties
By B. Gil, Ł. Mokrzycki, B. Sulikowski, Z. Olejniczak, S. Walas. 2010
186 citations recorded by the source corpus.
Abstract Two zeolites of different topology: ZSM-5 and ZSM-12 were subjected to desilication in the NaOH solutions of increasing concentrations. Changes in the properties of modified zeolites were investigated by several methods ( 29 Si and 27 Al MAS NMR, FTIR, SEM, XRD, and sorption techniques). It was shown that desilication led to the formation of mesopores, and indicated that the process started at the faulting sites called “silanol nests” for ZSM-5 while this mechanism for ZSM-12 was different. Acidic properties of parent and desilicated zeolites were investigated by the adsorption of pyridine and CO followed by IR spectroscopy. For both zeolitic series the number of Bronsted acid centres was virtually independent of the desilication progress (differences below 20%), while the number of Lewis centres increased by more than 100% in some cases. Pyridine thermodesorption experiment revealed the presence of the second type of Bronsted sites in desilicated zeolites, their acidic properties may be compared to the hydroxyls existing in mesoporous materials of M41S family.
Subfields: Industrial and Manufacturing Engineering, Inorganic Chemistry, Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/88710810b158067e7112bdfc634455183e500b60
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In Inorganic Chemistry
Citations in the corpus
- Siting and Distribution of Framework Aluminium Atoms in Silicon-Rich Zeolites and Impact on Catalysis (2012, background): “The absence of Si(2Si,2Al) atoms was reported for ZSM-12 with a Si/Al of l4 (48), and Al-O-Si-O-Al sequences were also not found in MCM-22 (Si/Al > 10) (49) and MCM-49 (Si/Al > 15) (49a).”