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Mechanism of HCl oxidation (Deacon process) over RuO 2

Mechanism of HCl oxidation (Deacon process) over RuO 2. Gerard Novell-Leruth. The Institute of Chemical Research of Catalonia. Scheme. Deacon process Ruthenium Oxide Reactivity on RuO 2 (110) Microkinetic analysis Conclusions. The Chlorine Tree. The Chlorine Tree.

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Mechanism of HCl oxidation (Deacon process) over RuO 2

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  1. Mechanism of HCl oxidation (Deacon process) over RuO2 Gerard Novell-Leruth

  2. The Institute of Chemical Research of Catalonia

  3. Scheme • Deacon process • Ruthenium Oxide • Reactivity on RuO2(110) • Microkinetic analysis • Conclusions

  4. The Chlorine Tree

  5. The Chlorine Tree The Production consumption per weight produced is near to iron and steel production. • Chloroalkali process • 2 NaCl + 2 H2O → Cl2 + H2 + 2 NaOH • 3600 -3300 kWh / ton of Chlorine • Deacon Process • 4 HCl + O2 → 2 Cl2 + 2 H2O

  6. Chlorine production

  7. Chlorine production • SumitomoChemicals • RuO2/TiO2 (rutile) • Highactivity • LowTemperature (300 ºC) • Stability • Production of 400 kton per year in a single reactor

  8. Scheme • Deacon process • Ruthenium Oxide • Reactivity on RuO2(110) • Microkinetic analysis • Conclusions

  9. RuO2 powder structure (001) (100) (101) (110)

  10. Different RuO2 activities Different nature of the exposed sites i.e. nanoparticle structure N. López, J. Gómez-Segura, R. P. Marín, J. Pérez-Ramírez, J.Catal., 255, 2008, 29-39

  11. RuO2 (110)

  12. RuO2 (110) 5Layers

  13. RuO2 (110) UnitCell 5Layers

  14. Computational details

  15. Scheme • Deacon process • Ruthenium Oxide • Reactivity on RuO2(110) • Microkinetic analysis • Conclusions

  16. Common proposed mechanism

  17. Oxygen adsorption O2 + 2* ↔ O2c* Eads=-0.66 eV

  18. Oxigen dissociation O2** ↔ 2 Oc* Ea=0.40 eV DE=-0.41 eV

  19. HCl reaction 2 configurations 1 reaction

  20. HCl reaction 2 configurations 1 reaction HCl* + Ob* ↔ Cl* + ObH* HCl* + Oc* ↔ Cl* + OcH* Ea < 0.01 eV Ea < 0.01 eV DE=-1.46 eV DE=-1.23 eV

  21. Water formation 2 configurations 1 reaction

  22. Water formation 2 configurations 1 reaction OcH* + OcH* ↔ Oc* + H2Oc* ObH* + OcH* ↔ Ob* + H2Oc* Ea = 0.38 eV Ea = 0.24 eV DE= 0.24 eV DE=-0.11 eV

  23. Water desorption H2Oc* ↔ H2O + * Eads= -0.90 eV

  24. Chlorine formation Clc* + Clc* ↔ Cl2 + 2 * Eads= -1.56 eV

  25. Scheme • Deacon process • Ruthenium Oxide • Reactivity on RuO2(110) • Microkinetic analysis • Conclusions

  26. Mechanism and reaction parameters Ea / eV ΔE / eV < 0.01 -0.66 0.38 -0.76 < 0.01 -1.46 < 0.01 -1.23 0.38 0.27 0.24 -0.11 0.55 -0.01 0.90 0.90 1.56 1.56 RuO2(110)

  27. Microkinetic modeling

  28. Microkinetic modeling

  29. Results: Cl2 production vs T and t Initial Conditions: P(O2) = 4·105 Pa P(HCl) = 2·105 Pa

  30. Results: Presure vs Temperature Experimental T regim Initial Conditions: P(O2) = 4·105 Pa P(HCl) = 2·105 Pa Time = 1 s P(O2) P(HCl) P(Cl2) P(H2O)

  31. Results: P and Coverage vs time Initial Conditions: P(O2) = 4E5 Pa P(HCl) = 2E5 Pa T = 570 K P(O2) P(HCl) P(H2O) P(Cl2) θ(ObH) θ(Clc) θ(Ob) θ(Oc) time / s

  32. Mechanism Our proposed mechanism contains the following elementary steps:

  33. Variations at microkinetic models Initial Conditions: P(O2) = 4E5 Pa P(HCl) = 2E5 Pa T = 570 K Full Model P(O2) P(O2) P(HCl) P(HCl) P(H2O) P(H2O) P(Cl2) P(Cl2) Reduced Model time / s

  34. Mechanism Our proposed mechanism contains the following elementary steps:

  35. Scheme • Deacon process • Ruthenium Oxide • Reactivity on RuO2(110) • Microkinetic analysis • Conclusions

  36. Conclusion • Mechanism of the global process • The bridge Oxygen acts as a reservoir of H • Microkinetic model with DFT results • Discussion of species in the process as function of the reaction conditions

  37. Acknowledgements THANKS FOR YOUR ATTENTION !!!

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