Wan Khairunnisa Wan Ramli
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Preferred name
Wan Khairunnisa Wan Ramli
Official Name
Wan Khairunnisa, Wan Ramli
Alternative Name
Ramli, W. K. W.
Ramli, Wan K. W.
Ramli, Wan Khairuzzaman Wan
Ramli, W. K. Wan
Main Affiliation
Scopus Author ID
18435070700
Researcher ID
DNN-0208-2022

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  • Publication
    Exsolution enhancement of metal-support CO oxidation perovskite catalyst with parameter modification
    ( 2021-05-24)
    Lew G.L.
    ;
    Naimah Ibrahim
    ;
    Abdullah S.
    ;
    Wan Daud W.R.
    ;
    Wan Khairunnisa Wan Ramli
    This study aimed to further tune the capability of active metal exsolution onto the surface of the CO oxidative perovskite catalyst La0.7Ce0.1Co0.3Ni0.1Ti0.6O3 by tuning the reducing parameter. Under same calcination temperature of 800℃, XRD analysis shown that the precursors with calcination duration of 6 hours (S2T8H6) was able to achieve similar crystalline structure to those with calcination duration of 12 hours (S2T8H12). In order for the active metal (CoNi) to be exsolved onto the perovskite surface, reducing parameter such as temperature and duration are deemed crucial to the reduction process. The exsolution of the active metals was observed when the samples were treated under reducing condition with varying temperatures of 550℃ and 700℃ and duration from 200 to 300 minutes. Through comparison with their EDX readings, S2T8H6 treated under 700℃ and 300 minutes (S2T8H6-R7H5) achieved the highest weight percentage of surface Cobalt and Nickel of 3.83 and 2.81. It was clear that by tuning the temperature and duration of reduction, the exsolution of the active metals onto the surface of the perovskite could be improved resulting in better exposure and dispersion of active metals onto the surface of catalyst.
  • Publication
    Enhancing carbon monoxide oxidation of Cobalt-Nickel containing a-deficient Perovskites through exsolution agents and reduction-oxidation pretreatment
    (Masyarakat Katalis Indonesia - Indonesian Catalyst Society (MKICS), 2025-04)
    Lew Guo Liang
    ;
    Wan Khairunnisa Wan Ramli
    ;
    Naimah Ibrahim
    ;
    Sureena Abdullah
    In this work, different types of exsolution agents and pretreatment processes, comprising reduction-oxidation (RO) components, were introduced to modulate the exsolution process of A-deficient perovskites, La₀.7Ce₀.₁Co₀.₃Ni₀.₁Ti₀.6O₃. The catalysts were assessed using field emission scanning electron microscopy with energy dispersive spectroscopy (FESEM/EDS), X-ray Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Their carbon monoxide (CO) oxidation activity was also compared. The results showed that the catalytic activity degraded at 520°C when hydrogen (E-H) was used as the exsolution agent. When RO components were introduced as exsolution agents (E-CO/O₂) or in the pretreatment (RO2% and RO18%), the deactivation at high temperatures was mitigated. The results of this study showed that RO18% was favourably pretreated with RO components, recording the highest CO conversion of 60.57% at 520°C and across all temperatures with no degradation at high temperature. It also recorded the lowest activation energy of 14.449 kJ/mol. The EDS, XRD, and XPS analyses of the catalyst demonstrated that the active sites for this reaction are primarily Co₂+ with Ni serving as the anchor between the metals and perovskites support. A high amount of lattice oxygen (O₂) with higher binding energy and chemisorbed O2 species also influenced the improved catalytic activity, attracting CO for reaction, reacting with the available surface O₂ and the faster replenishment of O₂ vacancies by the absorbed and bulk O2 lattice. These findings highlight the prospects of CO and O₂ inclusion in pretreatment for perovskite catalyst as options to reduce metal agglomeration and further improve CO oxidation activity.