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Author: search.filters.author.Prasertsab, Anittha

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    Cu encapsulated in hierarchical MFI zeolites for ethanol dehydrogenation to acetaldehyde
    (2026-04-09)
    Saenluang, Kachaporn
    ;
    Maineawklang, Narasiri
    ;
    Prasertsab, Anittha
    ;
    Sooknoi, Tawan
    ;
    Kegnæs, Søren
    In this contribution, we report the design of Cu nanoparticles encapsulated within both hierarchical and conventional MFI frameworks for the dehydrogenation of ethanol to acetaldehyde. The encapsulated catalysts were successfully synthesized via a hydrothermal method, using tetrabutylammonium hydroxide (TBAOH) and tetrapropylammonium hydroxide (TPAOH) as structure-directing agents (SDAs) for hierarchical and conventional frameworks, respectively. Characterization results showed that the hierarchical silicalite-1 zeolite (Cu@hieS-1) exhibited the simultaneous presence of mesopores and uniform Cu nanoparticles (∼2.3 nm), with high Cu dispersion (82.6%), thereby significantly improving active-site accessibility and reducing diffusion path lengths, eventually enhancing catalytic efficiency. Catalytic testing demonstrated that Cu@hieS-1 achieved 96% ethanol conversion and 82% acetaldehyde yield at 400 °C, outperforming conventional zeolites (15% ethanol conversion and 12% acetaldehyde yield). The reason for the improved catalytic activity over Cu@hieS-1 compared to the conventional ones relates to the fact that Cu@hieS-1 contains a higher proportion of Cu<sup>+</sup> species compared with the others, eventually leading to promoting acetaldehyde formation. Additionally, hierarchical zeolites exhibited enhanced catalytic stability, maintaining ∼80% conversion and 82% acetaldehyde yield. This work illustrates the benefits of the encapsulated catalyst in optimizing catalytic performances for sustainable acetaldehyde production.
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    Effects of zeolite frameworks and hierarchical structures on catalytic bioethanol dehydration: In-situ DRIFTS and DFT studies
    (2023-04-15)
    Iadrat, Ploychanok
    ;
    Yomthong, Krissanapat
    ;
    Rodaum, Chadatip
    ;
    Pornsetmetakul, Peerapol
    ;
    Thivasasith, Anawat
    Herein, the combined in-situ diffuse reflectance infrared Fourier transform spectroscopy and density functional theory studies were employed to investigate the effects of different zeolite frameworks and hierarchical structures on catalytic bioethanol dehydration. The findings reveal that different zeolite frameworks enable the formation of distinct intermediates, hence promoting different mechanistic pathways. Interestingly, the FER is highly selective to ethylene and inhibits the formation of by-products thanks to the confined porous structure of the FER. Although the pristine small pore FER often suffers from fast catalyst deactivation, the incorporation of hierarchical structures in the FER framework can mitigate this significantly. Accordingly, the catalytic stability of the hierarchical FER was improved remarkably with a high ethylene yield (∼95%), whereas the pristine FER suffers from fast deactivation. Additionally, coke formation over the hierarchical FER catalyst was also reduced significantly compared to that of the pristine FER. Importantly, the in-situ DRIFTS studies reveal that the different reaction pathways over hierarchical and commercial FER have been observed in which the hierarchical one promotes the monomeric pathway due to the facile desorption of corresponding products and intermediates, whilst the pristine one promotes bioethanol conversion via both pathways of monomeric and dimeric pathways to produce ethylene and diethyl ether, respectively.
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