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Kinetics reaction scheme_v1 3

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Reaction kinetics investigation scheme

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Kinetics reaction scheme_v1 3

  1. 1. Funda-mentals Thermo- Dynamics Kinetic Data bases Micro- kinetics Ab-initio methodsStarting point: If you intend to perform a thorough investigation of the reaction kinetics, you should startwith the fundamental basis: search for thermodynamics and kinetic databases (if available). Additionally,microkinetics and ab-initio modelling (e.g. using the DFT theory) could be considered.
  2. 2. Funda- Create reaction networkmentals Construct rate expressions Initial parameer estimates Thermo- Dynamics Kinetic Data bases Micro- kinetics Ab-initio methodsSecond step: The basic information is often prerequisite to allow to draw the reaction network, followedby construction of the reaction rate equations and make rough estimates of the kinetic parameters to beused as starting values in the parameter estimation. Besides open literature, information fromcomparable systems are important sources of information.
  3. 3. Funda- Create reaction network Reactor modelmentals Construct rate expressions Preferentially simple models Also: Dynamic operation Initial parameer estimates Thermo- Dynamics Kinetic Data bases Micro- kinetics Ab-initio methodsModelling: The next step is to set up your reactor model, based on the conservation of momentum, mass,and energy. In order to concentrate the effort on the reaction kinetics, these reactor models should bepreferentially simple (i.e. ideally stirred tank or plug-flow reactor). Non-steady state operation may beconsidered to increase the amount of information about the reaction system.
  4. 4. Funda- Create reaction network Reactor modelmentals Construct rate expressions Preferentially simple models Also: Dynamic operation Initial parameer estimates Thermo- Dynamics New Experimental data Kinetic (without transport limitations) Data bases Micro- kinetics Ab-initio methodsExperimental work: After selecting a suitable test reactor and suitable test conditions at which one canexclude disturbing phenomena such as transport limitations, non-homogeneous flow distribution, andinsufficient mixing can be excluded, a series of experiments should be carried out.
  5. 5. Funda- Create reaction network Reactor modelmentals Construct rate expressions Preferentially simple models Also: Dynamic operation Initial parameer estimates Thermo- Dynamics Parameter estimation New Experimental data Kinetic (without transport limitations) Data bases _ Micro- + kinetics Ab-initio Reaction kinetics methodsParameter estimation: The unknown kinetic rate parameters are optimized to fit to the experimental dataas well as possible using a suitable software package, which should also provide proper statisticalinformation concerning the fit(s) obtained.
  6. 6. Funda- Create reaction network Reactor modelmentals Construct rate expressions Preferentially simple models Also: Dynamic operation Initial parameer estimates Thermo- Dynamics Parameter estimation New Experimental data Kinetic (without transport limitations) Data bases _ Micro- + kinetics Design of experiments for: 1) Model discrimination Ab-initio 2) Improving parameter Reaction kinetics estimates methodsImproving the kinetics: In many cases the fit obtained with the initial set of experiments yields toounreliable kinetics. By using software suitable for (sequential) experimental design, you may determinethe most suitable experimental conditions for additional experiments to facilitate model discriminationand to reduce the uncertainty ranges of the rate parameters.
  7. 7. Funda- Create reaction network Reactor modelmentals Construct rate expressions Preferentially simple models Also: Dynamic operation Initial parameer estimates Thermo- Dynamics Parameter estimation New Experimental data Kinetic (without transport limitations) Data bases _ Micro- + kinetics Design of experiments for: 1) Model discrimination Ab-initio 2) Improving parameter Reaction kinetics estimates methods Effects of uncertaintiesTranslation to the production scale: An important but not easy step is to translate the remaininguncertainties in the kinetic model obtained to the uncertainty in the performance of the large-scaleindustrial reactor.

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