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Article
Tracking Catalyst Activity during Fluidized-bed Catalytic Cracking
Industrial and Engineering Chemistry Research (2008)
  • Rafael Maya-Yescas
  • Gladys Jiménez-García, Universidad Michoacana de San Nicolas de Hidalgo
  • Ricardo Aguilar-López
  • Elizabeth León-Becerril, Universidad Autónoma de Yucatán
Abstract

Fluidized- bed Catalytic Cracking (FCC) of vacuum gas oils, which produces aggregated value liquid fuels such as gasoline and liquid petroleum gas, is an important process in petroleum refining. Cracking reactions take place in risers, which are transported solid bed devices. In order to model risers it is necessary to develop kinetic schemes; however complex catalyst deactivation, reaction paths and non-isothermal behaviour of these adiabatic units make difficult to propose accurate schemes. The main mechanism of catalyst deactivation has been under research for more than 60 years, being related to coke formation during FCC reactions and the consequent active sites coverage and catalyst’s pore blockage. Although it is usual to model these phenomena as function of “time-on-stream”, it is possible to explain it in terms of effectiveness factors. If pore blockage is noticeable, then different activity related to each reactant is reflected by the relative magnitude of individual effective diffusion coefficients; unfortunately, these transport parameters are difficult to measure. In this work, a theoretical methodology based on the comparison of yield to products from different feed stocks is proposed to track catalyst activity dynamics; estimation functions are based on fundamental transport parameters, mainly effective diffusion, inside the catalyst particle. Experimental results obtained in MAT and industrial reactors are used to adjust values of catalytic activity and probe the approach proposed; simulation results for an industrial riser reactor confirm the satisfactory description of the activity profiles.

Keywords
  • Catalyst activity,
  • catalytic cracking,
  • deactivation,
  • effective diffusion,
  • effectiveness factors,
  • Thiele modulus.
Disciplines
Publication Date
Fall October 15, 2008
Citation Information
Rafael Maya-Yescas, Gladys Jiménez-García, Ricardo Aguilar-López and Elizabeth León-Becerril. "Tracking Catalyst Activity during Fluidized-bed Catalytic Cracking" Industrial and Engineering Chemistry Research Vol. ASAP (2008)
Available at: http://works.bepress.com/ricardo_aguilar_lopez/20/