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Ethylbenzene dehydrogenation to styrene over fresh and used commercial catalysts

Baghalha, M ; Sharif University of Technology | 2011

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  1. Type of Document: Article
  2. Publisher: 2011
  3. Abstract:
  4. Dehydrogenation of ethylbenzene (EB) to produce styrene (ST) monomer is commercially performed over potassium-promoted iron oxide catalysts. Catalyst deactivation due to coke deposition and loss of potassium is a major operation and economic drawback in this process. To better evaluate the performance change of these catalysts over their life-cycle, dehydrogenation of EB to ST over the fresh and used commercial catalysts was experimentally investigated at temperatures from 590 to 639°C under atmospheric pressure. The fresh and the used catalysts were obtained from a styrene plant. The used catalyst had been continuously operated for two years under severe plant conditions. The catalyst activity tests were performed in a lab-scale continuous fixed bed reactor, maintained at constant temperature. For the fresh catalyst, the yield of styrene increased with a decrease in LHSV and reached its highest value of 79% at 0.48 h-1 and T=627 °C. At the same experimental conditions, it was found that the selectivity of styrene for the used catalyst was higher than that for the fresh catalyst. However, the reaction rates and conversion in the used catalyst were considerably lower than that in the fresh catalyst. The transient effect of coke deposition on the EB conversion of the fresh catalyst was also investigated. Due to rapid coke deposition in the first 6 hour of these experiments, the fresh catalyst lost about 25% of its initial activity before reaching pseudo steady state conditions
  5. Keywords:
  6. Conversion ; Potassium-promoted iron oxide catalyst ; Selectivity ; Used catalyst ; Coke deposition ; Commercial catalyst ; Constant temperature ; Ethylbenzene dehydrogenation ; Experimental conditions ; Fixed bed reactor ; Fresh catalysts ; Initial activity ; Iron oxide catalyst ; Pseudo-steady-state conditions ; Styrene plants ; Transient effect ; Yield of styrene ; Atmospheric pressure ; Catalyst deactivation ; Chemical reactors ; Dehydrogenation ; Ethylbenzene ; Iron oxides ; Potassium ; Reaction rates ; Ship conversion ; Styrene ; Catalyst selectivity
  7. Source: AIChE Annual Meeting, Conference Proceedings ; 2011 ; 9780816910670 (ISBN)
  8. URL: http://www3.aiche.org/proceedings/Abstract.aspx?PaperID=213198