Solvent-free ketalization of polyols over germanosilicate zeolites: The role of the nature and strength of acid sites
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11310%2F20%3A10424022" target="_blank" >RIV/00216208:11310/20:10424022 - isvavai.cz</a>
Result on the web
<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=m1HjQAgSyf" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=m1HjQAgSyf</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1039/d0cy01662d" target="_blank" >10.1039/d0cy01662d</a>
Alternative languages
Result language
angličtina
Original language name
Solvent-free ketalization of polyols over germanosilicate zeolites: The role of the nature and strength of acid sites
Original language description
Isomorphic substitution of silicon for germanium affords germanosilicate zeolites with weak acid centers capable of catalyzing key reactions such as Baeyer-Villiger oxidation of ketones and etherification of levulinic acid. Herein, we show for the first time that UTL (Si/Ge = 4.2) and IWW (Si/Ge = 7.2) germanosilicate zeolites are active and selective catalysts of polyol (e.g., ethylene glycol, glycerol and 1,4 butanediol) ketalization to dioxolanes. Large-pore IWW outperformed the extra-large-pore UTL zeolite in the ketalization of polyols, thus indicating diffusion limitations in bulky platelet-like UTL crystals. FTIR spectroscopy of adsorbed pyridine revealed the Lewis acidity of the UTL zeolite, whereas the more active IWW catalyst was characterized by water-induced Bronsted acidity. Increasing the activation temperature (200-450 degrees C) reduced the concentration of Bronsted acid centers in the IWW germanosilicate (i.e., 0.16; 0.07 and 0.05 mmol g(-1) for T-act = 200, 300 and 450 degrees C, respectively) but increased the number of Lewis acid sites in both zeolites. Under optimized reaction conditions (e.g., acetone/glycerol = 25, T-act = 300 degrees C), almost total transformation of glycerol into solketal was achieved within 3 h of reaction time over the IWW zeolite at room temperature (>99% yield of the target product). The results from the present study clearly show that weak acid centers of germanosilicate zeolites can serve as active sites in ketalization reactions.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10403 - Physical chemistry
Result continuities
Project
Result was created during the realization of more than one project. More information in the Projects tab.
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)
Others
Publication year
2020
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Catalysis: Science and Technology
ISSN
2044-4753
e-ISSN
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Volume of the periodical
10
Issue of the periodical within the volume
24
Country of publishing house
GB - UNITED KINGDOM
Number of pages
11
Pages from-to
8254-8264
UT code for WoS article
000598674500010
EID of the result in the Scopus database
2-s2.0-85098102986