KMITL

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

Browse

Settings

Author: search.filters.author.Kim-Lohsoontorn, PattarapornSubject: search.filters.subject.Catalyst

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,
    Modification of acid–base properties of metal-doped ZnO catalysts for the transesterification of propylene carbonate with methanol to dimethyl carbonate
    (2025-04-01)
    Ieamviteevanich, Pimchanok
    ;
    Kim-Lohsoontorn, Pattaraporn
    ;
    Seeharaj, Panpailin
    This study investigated the effect of metal dopants on the surface properties of ZnO-based catalysts for the transesterification of propylene carbonate (PC) with methanol to produce dimethyl carbonate (DMC). A series of metal-doped ZnO nanocatalysts (M-ZnO, where M is Ca<sup>2+</sup>, Cu<sup>2+</sup>, Ce<sup>3+</sup>, La<sup>3+</sup>, and Y<sup>3+</sup> with the mol ratio of Zn<sup>2+</sup>/M<sup>x+</sup> = 4) were prepared by a simple co-precipitation method followed by calcining in air at 673 K for 5 h. Introducing different metal cations into the ZnO system decreased crystallite size and created surface defects of exposed cations and oxygen vacancies, increasing surface-active acid and basic sites. The catalytic performance for DMC production was ranked as follows: Ca-ZnO < Cu–ZnO < ZnO < Ce-ZnO < Y-ZnO < La-ZnO. La-ZnO showed the highest performance of all catalysts, with 67% PC conversion, 67% DMC selectivity, and 45% DMC yield. The improvement of catalytic activity was correlated with an increase in the concentration of moderate and strong acid–base functionalities on the La-ZnO surfaces for participating in the reaction of PC and methanol to form DMC.