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Author: search.filters.author.Danuthai, Tanate

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    Effect of extra-framework cesium on the deoxygenation of methylester over CsNaX zeolites
    (2011-12-15)
    Danuthai, Tanate
    ;
    Sooknoi, Tawan
    ;
    Jongpatiwut, Siriporn
    ;
    Rirksomboon, Thirasak
    ;
    Osuwan, Somchai
    The deoxygenation of methyl octanoate has been investigated over Cs-containing NaX zeolite catalysts at atmospheric pressure with He carrier gas and methanol as a co-feed. By varying the preparation procedures, different amounts of extra-framework Cs were left on the catalyst. The presence of extra-framework Cs affects the acid-basic characteristics of the catalysts and consequently their activity, stability, and particularly the product selectivity. That is, when the amount of extra-framework Cs increases, the corresponding increase in basicity enhances decarbonylation activity as well as catalyst stability. In this case, the deoxygenation of methyl octanoate on CsNaX catalysts was found to yield heptenes and hexenes as main products via surface decomposition of octanoate-like species. When the amount of extra-framework Cs was reduced, the hexene yield readily increased. The enhancement in hexene production can be ascribed to both, a decreased basicity that reduces decarbonylation and to a greater space available within the zeolite cavity for formation of a rather bulky cyclic-like intermediate that leads to hexene. In addition, weakly acidic sites, generated after the excess Cs was removed, resulted in relatively higher yield of inner-olefin product. When Cs was not present in the catalyst (i.e., NaX), other products such as aromatics and coupling compounds were observed. These compounds are less desirable for transportation fuel applications. © 2011 Elsevier B.V. All rights reserved.
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    Deoxygenation of model biofuel compounds over CsNaX zeolite catalyst
    (2008-12-01)
    Danuthai, Tanate
    ;
    Peralta, Maria A.
    ;
    Sooknoi, Tawan
    ;
    Osuwan, Somchai
    ;
    Lobban, Lance L.
    The deoxygenation of methyl octanoate and benzaldehyde over CsNaX zeolite catalyst has been investigated as a model for reactions for production of hydrocarbon fuels from bio-oxygenates. The CsNaX zeolite used in the study was prepared by ion exchange of NaX with a CsNO<inf>3</inf>/CsOH solution to a 50% exchange level. The decarbonylation activity, selectivity, and stability of the CsNaX catalyst were enhanced when methanol was co-fed for the reaction of methyl octanoate. TPD studies suggest that methyl octanoate first decomposes to an octanoate-like species. The decomposition of such species leads to the formation of heptenes and hexenes as major products. Octenes and hydrogenated products are formed in lesser amounts via hydrogenation / hydrogenolysis using hydrogen produced on the surface from methanol decomposition, but not from gas phase H<inf>2</inf>.