Chemical Engineering / Kimya Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/14

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Author: search.filters.author.Kugler, Edwin L.Subject: search.filters.subject.Metal contamination

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  • Article
    Citation - WoS: 15
    Citation - Scopus: 16
    Coke Content of Spent Commercial Fluid Catalytic Cracking (fcc) Catalysts: Determination by Temperature-Programmed Oxidation
    (Springer Verlag, 2003) Bayraktar, Oğuz; Kugler, Edwin L.
    Zeolite catalysts are widely used in oil refinery and petrochemical industries. Fluid catalytic cracking (FCC) catalysts used in a refinery consist of Y zeolite, a silica-alumina matrix and a binder. In this study, spent FCC catalysts were prepared by cracking sour imported heavy gas oil (SIHGO) in a microactivity test unit. The total amount of coke and the hydrogen-to-carbon ratio (H/C) in the coke for spent FCC catalysts contaminated with metals were determined using temperature-programmed oxidation (TPO). Total H/C ratios of the coke on FCC catalysts were found to be in the range of 0.4 to 1, indicating the majority of the coke consists of polyaromatic species. H/C ratio decreased with increasing coke contents on the catalysts. This ratio was found to be higher for the catalyst with high metal concentration compared to the catalyst with relatively low metal concentration. The high H/C ratio for highly contaminated FCC catalyst was attributed to the formation of hydrogen rich coke by hydrogenation reactions catalyzed by the contaminant metals on the catalyst. After hydrogen pre-treatment both coke amount and H/C ratio decreased significantly. This was due to the decrease in the hydrogenation activities of the contaminant-metals in their reduced forms.
  • Article
    Citation - WoS: 29
    Citation - Scopus: 32
    Visualization of the Equilibrium Fcc Catalyst Surface by Afm and Sem-Eds
    (Kluwer Academic Publishers, 2003) Bayraktar, Oğuz; Kugler, Edwin L.
    The deposition of metal contaminants (e.g., Ni, V, and Fe) from the hydrocarbon feed causes the deactivation of fluid catalytic cracking (FCC) catalyst used in petroleum refining. It is very important to understand the changes in the morphology and chemical composition on the catalyst surface and how these structural and chemical changes affect the catalyst performance. In this research, metal-contaminated FCC catalysts from a commercial unit have been characterized using AFM together with SEM-EDS. The AFM images showed the surface pores as well as the features that surround the pore's entrance on the catalyst surface. Catalyst surface contains debris that appear as bright spots in AFM images. SEM-EDS results have shown the presence of iron in these bright spots. Fe enrichment at the catalyst particle surface was also confirmed by XPS analyses.