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Ert 316 CHEMICAL reaction engineering multiple reactions

Ert 316 CHEMICAL reaction engineering multiple reactions. By Noor Amirah Abdul Halim. Type of reactions. Parallel reactions Series reactions Complex reactions (parallel and series reactions) Independent reactions. Desired & undesired reaction. Selectivity & yields.

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Ert 316 CHEMICAL reaction engineering multiple reactions

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  1. Ert 316 CHEMICAL reaction engineeringmultiple reactions By Noor Amirah Abdul Halim

  2. Type of reactions • Parallel reactions • Series reactions • Complex reactions (parallel and series reactions) • Independent reactions

  3. Desired & undesired reaction

  4. Selectivity & yields Selectivity : the ratio of (reaction rate/mol/flowrate) of desired product to the (reaction rate/mol/flowrate) of undesired product Instantaneous selectivity Overall selectivity Instantaneous yield Overall yield Yield: the ratio of (reaction rate/mol/flowrate) of desired product formed to the (reaction rate/mol/flowrate) the reactant either fed or consumed Batch flow

  5. Design equation for reactors involving multiple reactions reaction rate (r j) is a NET rate of reactions USE only molar flow rate (Fj) and concentration (Cj) DO NOT USE conversion (xj) DO NOT USE stoichiometry table to relate change in CB and change in CA

  6. Modification of the algorithm for multiple reaction

  7. Parallel reactions • Selectivity for single reactant system Thus, Consider some of reactor operating scenarios to maximize the selectivity ( SD/U (max) )

  8. Need highCAto favor Dproduction ( to increase selectivity) CA~ SD/U CA will always start at high value CA in a perfectly mixed CSTR is always at its lowest value

  9. Need lowCAto favor Dproduction ( to increase selectivity) CA~ SD/U CA in a perfectly mixed CSTR is always at its lowest value

  10. So, CAcannot be used as operating parameters to maximize the selectivity Thus the solution is: E = Activation Energy recall Thus, to achieve high selectivity: * higher energy requires higher temperature

  11. Selectivity for two reactant system For high SD/U, maintain both CA and CB as high as possible

  12. For high SD/U,maintain high CAandlowCB

  13. For high SD/U,maintain both CAandCBas low as possible

  14. For high SD/U,maintain low CAandhighCB

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