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Investigation of the Effect of Oxygen Feed Rate on the Oxidative Dehydrogenation of Ethane

Torkaman Asadi, Mahsa | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58674 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Khorashe, Farhad
  7. Abstract:
  8. Ethylene is a cornerstone of the petrochemical industry, serving as the primary feedstock for polyethylene, ethylene dichloride, ethylene oxide, ethylbenzene and many other derivatives. The conventional production route, steam cracking of hydrocarbons, relies on extremely high furnace temperatures at near-atmospheric pressure. Although catalytic dehydrogenation of paraffins has long been practiced as an alternative, its commercial performance is constrained by equilibrium limitations, rapid coke deposition and irreversible catalyst deactivation. Oxidative dehydrogenation of ethane (ODHE), in which oxygen is introduced in a controlled manner, offers a promising means of overcoming these drawbacks and has attracted substantial research attention in recent years. This study examines how the inlet O₂/ethane ratio influences the behavior of a shell-and-tube fixed-bed reactor packed with a Ni–Nb–O catalyst. Ethane–air mixtures flow through the tubes, while a coolant circulates in the shell. The kinetic scheme includes: (i) the desired ethane-to-ethylene conversion, (ii) coke formation via polymerisation of ethane and ethylene, and (iii) coke combustion with oxygen. Power-law rate expressions were adopted for every step, and one-dimensional pseudo-homogeneous mass- and energy-balance equations were solved with a Backward Differentiation Formula. Simulation results indicate that, owing to the presence of oxygen and the nature of the Ni–Nb–O catalyst, coke accumulation is modest; catalyst deactivation only becomes noticeable after several days, with activity declining to 0.90 after 35 days on stream. The optimum oxygen fraction, yielding the highest ethylene selectivity while simultaneously promoting coke burn-off, corresponds to 30 % of the total feed molar flow. Accordingly, a feed composition containing roughly one-third oxygen is recommended for optimal reactor performance
  9. Keywords:
  10. Dynamic Simulation ; Ethylene ; Coke Formation ; Oxidative Dehydrogenation ; Ethane ; Shell-and-Tube Fixed Bed Catalytic Reactor ; Ni-Nb-O Catalyst

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