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Hierarchical Porous WO3@SiO2Self-Standing Monolithic Catalysts and Their Efficient Cycling “Cosolvent-Free” Friedel–Crafts Alkylation/Acylation Catalytic Properties
- Source :
- Chemistry of Materials; August 2023, Vol. 35 Issue: 16 p6502-6516, 15p
- Publication Year :
- 2023
-
Abstract
- Taking advantage of tungsten oxide inherent Brønsted–Lewis acidity, the first series of WO3–SiO2(HIPE) monolithic (MUB-104(x) series) catalysts bearing multiscale porosity have been designed through integrative chemistry. At the microscopic length scale, beyond X-ray diffraction (XRD) revealing the WO3monoclinic structure, local electron spin resonance (ESR) spectroscopy addresses g values clearly located at the frontier between extended WO3phases and polyanion clusters, in agreement with scanning transmission electron microscopy high-angle annular dark field (STEM-HAADF) investigations. NH3-TPD shows that when the tungsten loading is increased from 10 wt % for MUB-104(1) to 24 wt % for MUB-104(3), the amount of acidic sites significantly decreases from 0.35 to 0.08 mmol of NH3g–1, respectively, in agreement with the particle sizes. The MUB-104(x) series offers efficient cosolvent-less heterogeneous cycling catalysis toward both Friedel–Crafts alkylation and acylation syntheses. MUB-104(1) carries the highest turnover number (TON) of 121 and turnover frequency (TOF) of 20 h–1, while for acylation, MUB-104(1) carries the highest TON of 117 and TOF of 26 h–1. Besides, we find out that the catalysts offer good selectivity, where 30/70% of ortho- and para-substituted alkylated products are obtained. Considering the acylation reaction, the selectivity is even higher, reaching 100% toward the para-substituted acylated product. The catalyst, due to its intrinsic monolithic character, can be easily extracted from the reactive media, recycled, and re-employed further.
Details
- Language :
- English
- ISSN :
- 08974756
- Volume :
- 35
- Issue :
- 16
- Database :
- Supplemental Index
- Journal :
- Chemistry of Materials
- Publication Type :
- Periodical
- Accession number :
- ejs63699153
- Full Text :
- https://doi.org/10.1021/acs.chemmater.3c01479