Chemical Engineering / Kimya Mühendisliği

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

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Subject: search.filters.subject.Fluidized catalytic cracking catalysts

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  • Article
    Citation - WoS: 11
    Citation - Scopus: 14
    Effect of Pretreatment on the Performance of Metal-Contaminated Fluid Catalytic Cracking (fcc) Catalysts
    (Elsevier Ltd., 2004) Bayraktar, Oğuz; Kugler, Edwin L.
    Effects of both hydrogen and methane pretreatment on the performance of metal-contaminated equilibrium fluid catalytic cracking (FCC) catalysts from a refinery were investigated. Both hydrogen and methane pretreatment at 700°C were proven to be advantageous since the yields of hydrogen and coke from sour imported gas oil (SIHGO) cracking decrease while light cycle oil (LCO) and gasoline yields increase. The catalysts pretreated with hydrogen have shown slightly better improvement than the catalysts pretreated with methane. The decrease in the yields of hydrogen and coke was attributed to decrease in the dehydrogenation activity of vanadium oxides, which are present at high concentrations on the equilibrium FCC catalysts. This decrease in dehydrogenation activity after the pretreatment was also confirmed by low hydrogen-to-methane ratio. It was found that reduced vanadium has lower dehydrogenation activity since it produces less coke and hydrogen compared to oxidized vanadium. Hydrogen transfer reactions were evaluated by measuring C4 paraffin-to-C4 olefin ratios. Hydrogen transfer reactions decreased with increasing metal concentration. Both hydrogen and methane pretreatment caused the hydrogen transfer reactions to increase. Improved hydrogen transfer reactions caused an increase in the gasoline range products.
  • Article
    Citation - WoS: 24
    Citation - Scopus: 25
    Temperature-Programmed Reduction of Metal-Contaminated Fluid Catalytic Cracking (fcc) Catalysts
    (Elsevier Ltd., 2004) Bayraktar, Oğuz; Kugler, Edwin L.
    A temperature-programmed reduction study of equilibrium fluid catalytic cracking (FCC) catalysts has shown three hydrogen-consumption peaks associated with contaminanted metals. A low-temperature peak, located near 510°C, is produced by the reduction of several components in the catalyst. Highly-dispersed vanadium contributes to this peak. A high-temperature peak, located near 800°C, is produced by reduction of nickel aluminate or nickel silicate compounds. A linear relationship exists between the area of the high-temperature peak and nickel concentration on equilibrium catalysts. An intermediate-temperature peak, located near 690°C, appears to be related to some form of vanadium compound. The intermediate-temperature peak does not occur on low-vanadium-concentration equilibrium catalysts, but is observed at higher vanadium-contamination levels. The presence of the 690°C peak was found by deconvoluting hydrogen-consumption data. The existence of this intermediate-temperature peak was proven by external reduction of highly-contaminated equilibrium catalyst at 500 and 700°C. External reduction at 500°C removes the low-temperature peak from the temperature-programmed reduction (TPR) spectrum. External reduction at 700°C removes both the low-temperature and intermediate-temperature peaks from the TPR spectrum. The difference in spectrum between calcined and 700°C reduced samples shows a clear spectrum with only the low and intermediate-temperature peaks present.