KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Settings

Author: search.filters.author.Srinives, SiraSubject: search.filters.subject.Dimethyl carbonate

Search Results

Now showing 1 - 2 of 2
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    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.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Improvement of surface properties of metal doped-CeO2 nanospindle catalysts for direct synthesis of dimethyl carbonate from CO2 and methanol
    (2023-06-01)
    Seeharaj, Panpailin
    ;
    Saenman, Thanita
    ;
    Phiwhom, Thanabat
    ;
    Muangsuwan, Chutanan
    ;
    Srinives, Sira
    To utilize carbon dioxide (CO<inf>2</inf>) which is the main greenhouse gas, this study developed effective metal doped-CeO<inf>2</inf> nanospindle catalysts for conversion of CO<inf>2</inf> and methanol into dimethyl carbonate (DMC). Ce<inf>0.9</inf>M<inf>0.1</inf>O<inf>2</inf> nanospindles (where M is a transition metal, i.e., Zr, Fe, Cu and Co) were prepared by a template-free hydrothermal method. The substitution of different valence and size cations, including Zr<sup>4+</sup>, Fe<sup>3+</sup>, Cu<sup>2+</sup> and Co<sup>2+</sup>, for Ce<sup>4+</sup> sites in the fluorite CeO<inf>2</inf> lattice induced the defect formation of surface-active sites of exposed Ce<sup>3+</sup> and oxygen vacancies through the charge compensation and redox pair reactions. Ce<inf>0.9</inf>Fe<inf>0.1</inf>O<inf>2</inf> solid solution with well-preserved spindle shaped morphology showed the highest catalytic performance by giving DMC yield at 3.56 mmol.g<inf>cat</inf><sup>−1</sup> with 100% DMC selectivity. The improvement of catalytic activity was attributed to the higher proportion of surface defect sites and variation of acid-base properties caused by the integration of Fe dopants into CeO<inf>2</inf> ionic system.