Seeharaj, Panpailin

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Seeharaj, Panpailin
Alternative Name
Seeharaj, P.
Main Affiliation
Email
panpailin.se@kmitl.ac.th

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    Item type:Publication,
    Ultrasonically assisted surface modified CeO2 nanospindle catalysts for conversion of CO2 and methanol to DMC
    (2022-11-01)
    Kulthananat, Tachatad
    ;
    Kim-Lohsoontorn, Pattaraporn
    ;
    Seeharaj, Panpailin
    This study developed a facile and effective approach to engineer the surface properties of cerium oxide (CeO<inf>2</inf>) nanospindle catalysts for the direct synthesis of dimethyl carbonate (DMC) from CO<inf>2</inf> and methanol. CeO<inf>2</inf> nanospindles were first prepared by a simple precipitation method followed by wet chemical redox etching with sodium borohydride (NaBH<inf>4</inf>) under high intensity ultrasonication (ultrasonic horn, 20 kHz, 150 W/cm<sup>2</sup>). The ultrasonically assisted surface modification of the CeO<inf>2</inf> nanospindles in NaBH<inf>4</inf> led to particle collisions and surface reduction that resulted in an increase in the number of surface-active sites of exposed Ce<sup>3+</sup> and oxygen vacancies. The surface modified CeO<inf>2</inf> nanospindles showed an improvement of catalytic activity for DMC formation, yielding 17.90 mmol·g<inf>cat</inf><sup>−1</sup> with 100 % DMC selectivity. This study offers a simple and effective method to modify a CeO<inf>2</inf> surface, and it can further be applied for other chemical activities.
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    Correlation of urea precipitation temperature with phase formation, morphology, and catalytic activity for CO2 conversion of CeO2
    (2025-08-01)
    Seeharaj, Panpailin
    ;
    Duangtanon, Jenjira
    ;
    Sreemueang, Chanakan
    ;
    Noppharat, Phetchphalin
    ;
    Kulthananat, Tachatad
    This study proposes a simple method for tailoring the morphology and activity of cerium oxide (CeO<inf>2</inf>) catalysts in converting carbon dioxide (CO<inf>2</inf>) and methanol to green organic carbonate, dimethyl carbonate (DMC), to utilize and reduce CO<inf>2</inf> emissions. CeO<inf>2</inf> was prepared by urea precipitation at 85, 105, and 125 °C for 2 h, then calcining at 600 °C for 2 h. The phase structure and morphology of CeO<inf>2</inf> correlated with the urea hydrolysis rate. A low degree of supersaturation at 85 °C led to heterogeneous precipitation of cerium oxycarbonate (Ce<inf>2</inf>O(CO<inf>3</inf>)<inf>2</inf>.H<inf>2</inf>O) and CeO<inf>2</inf> with spherical morphology, while a higher degree of supersaturation at 105 °C and 125 °C resulted in homogeneous precipitation of single-phase Ce<inf>2</inf>O(CO<inf>3</inf>)<inf>2</inf>.H<inf>2</inf>O with spindle and elongated octahedral morphology, respectively. The spindle-shaped CeO<inf>2</inf> prepared at 105 °C with a predominant surface (111) facet showed the highest catalytic activity, with a DMC yield of 18.81 mmol.g<inf>cat</inf><sup>−1</sup>. The enhanced catalytic efficiency of spindle-shaped CeO<inf>2</inf> was due to the high concentration of surface-active defect sites of exposed cerium cations and oxygen vacancies, which optimized the number of acid–base sites in adsorbing and activating CO<inf>2</inf> and methanol to produce DMC.