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Author: search.filters.author.Choojun, KittisakSubject: search.filters.subject.Deoxygenation

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    Highly active and stable Ni–W/SiO2 catalyst derived from W incorporated on Ni phyllosilicate for deoxygenation of triglycerides into green biofuel range hydrocarbons
    (2025-10-01)
    Praikaew, Wanichaya
    ;
    Prameswari, Jedy
    ;
    Ratchahat, Sakhon
    ;
    Chaiwat, Weerawut
    ;
    Sakdaronnarong, Chularat
    Highly active and stable Ni–W/SiO<inf>2</inf> catalyst derived from W incorporated into Ni phyllosilicate (Ni-PS) was prepared by the ammonia evaporation (AE) method, and benchmarked with the catalyst prepared by the impregnation method (IM). Their catalytic activities were evaluated for deoxygenation of triglycerides into green biofuel-range hydrocarbons. The Ni-PS structure demonstrated a large surface area with strong interaction between Ni<sup>2+</sup> and SiO<inf>2</inf>, resulting from the incorporation of Ni<sup>2+</sup> into the silica framework, which led to highly dispersed Ni⁰ after H<inf>2</inf> reduction. Additionally, the H<inf>2</inf> adsorption and desorption capabilities, together with a substantial quantity of Lewis acid sites, were advantageous features of Ni-PS catalysts compared to Ni-IM and 5 W/Ni-IM catalysts. Ex situ and in situ structural characterizations revealed the generation of Ni⁰ and W⁰ states, along with remaining W<sup>4+</sup> species after H<inf>2</inf> reduction. The 5 W/Ni-AE catalyst exhibited stable performance up to 60 h on stream, producing consistent yields of 30 % jet fuel and 40 % diesel, which was attributed to its high porosity, small Ni⁰ particle sizes, enhanced H<inf>2</inf> adsorption–desorption capacities, and abundant Lewis acid sites. Consequently, the heterogeneous 5 W/Ni-AE catalyst shows significant practical relevance for generating green biofuel from oil-derived feedstock in sustainable biorefineries.
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    Deoxygenation of heptanoic acid to hexene over cobalt-based catalysts: A model study for α-olefin production from renewable fatty acid
    (2020-07-25)
    Phichitsurathaworn, Ploynisa
    ;
    Choojun, Kittisak
    ;
    Poo-arporn, Yingyot
    ;
    Sooknoi, Tawan
    Deoxygenation of heptanoic acid, a model compound, over bimetallic cobalt (Co-Pt, Co-Au, Co-Pd, Co-Ru) supported silica catalysts, was examined for α-olefin production. The catalysts were prepared by conventional impregnation of the metal precursors on silica and characterized by XRF, TEM, H<inf>2</inf>-TPR, acetic acid-TPD, and XANES. Catalytic testing was performed in a fixed-bed flow reactor under atmospheric H<inf>2</inf> pressure. Monometallic cobalt catalysts yielded mainly 1-hexene, but rapid deactivation was observed. Incorporation of 0.5%wt secondary metal, particularly Pt, increases activity and stability under H<inf>2.</inf> A relatively higher olefin/paraffin ratio can be obtained from the reaction over 5%Co+0.5%Pt/SiO<inf>2</inf> when compared to that with higher Pt loading. The co-impregnation method offers Co-Pt catalysts with stability higher than that prepared by the sequential impregnation method. Over cobalt-based catalysts, the deoxygenation is proposed to proceed via reduction of heptanoic acid to heptanal that is an intermediate for decarbonylation to hexene; while other side reactions are suppressed.