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Kinetics and Mechanisms of hydrogenation of DMO PowerPoint Presentation
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Kinetics and Mechanisms of hydrogenation of DMO

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  1. Kinetics and Mechanisms of hydrogenation of DMO Li Siming 2012.9.8

  2. C. Perego, S. Peratello, Catalysis Today 1999, 52, 133-145. Internal Diffusion Effects

  3. 小于0.1(0.15)时,可认为无内扩散影响。

  4. External Diffusion Effects C. Perego, S. Peratello, Catalysis Today 1999, 52, 133-145.

  5. 小于0.05时,可认为无外扩散影响。

  6. CH3O C C OCH3 + H2 (A) H (MG) (ME) OH (B) H (EG) (E) CH3CH2OH+ H2O Pathway of DMO hydrogenation OH OH O O O OH OH O O OH OH OH OH OH OH O Cu/SiO2 Cu/SiO2 Cu/SiO2 Cu/SiO2 Cu/SiO2 CH3O C C OCH3 + H2 CH3O C CH2+ CH3OH CH3O C CH2 + H2 CH3O C CH2 H2C CH2 + CH3OH CH3O C C OCH3 CH3O C CH2 + H2 H2C CH2 + H2 H OH

  7. ME* ( MG* Et* EG* MG + * ) Et + * ME + * EG + * H2 + 2# 2H # DMO * + 2 H# A* + 2# (1) A* + 2H# + * MG* + 2# + ME* (2) B* +2 # (3) MG* + 2H# B* + 2H# + * EG* + ME* + 2# (4) EG* + 2H# Et* + H2O + 2# (5) Ester un-dissociative adsorption Hydrogen dissociatively adsorb on the active site: DMO * DMO + * #, *: Different active site

  8. Hydrogen un-dissociative adsorption Hydrogen un-dissociatively adsorb on the active site: This way is similar to hydrogen dissociative. The rate control step may be Hydrogen adsorption, surface(1~4) or ester adsorption. Using (1+KHpH) instead of in the rate expression. When the rate is is determined by the un-dissociative adsorption of hydrogen, the rate expression is:

  9. Ester Dissociative adsorption

  10. H2 + 2# 2H # CH3OOCC*O +OCH3 * (1) DMO + 2* A B CH3OOCC*O+ 3H# CH3OOCC*H2OH (MG)+ 3# (2) MG + * (3) MG* MG + 2* HOCH2C*O +OCH3 * (4) HOCH2C*H2OH + 3# (5) HOCH2C*O +3H# EG* + 2H# Et* + H2O + 2# (7) OCH3 * + H# ME* + # (6) ME* ME + * EG + * EG* Et* Et + * Pathway of ester dissociative adsorption C #, *: Different active site

  11. H2 + 2# 2H # CH3OOCC*O +OCH3 * (9) DMO + 2* CH3OOCC*OH+ # (1) CH3OOCC*O + H# CH3OOCC*OH+ H# CH3OOCC*HOH+ # (2) CH3OOCC*HOH+ H# CH3OOCC*H2OH(MG)+ # (3) MG + * (7) MG* MG + 2* HOCH2C*O +OCH3 * (8) HOCH2C*OH + # (4) HOCH2C*O +H# HOCH2C*HOH + # (5) HOCH2C*OH +H# EG* + 2H# Et* + H2O + 2# OCH3 * + H# ME* + # (10) ME* ME + * EG + * EG* Et* Et + * The most possible pathway #, *: Different active site HOCH2C*H2OH + # (6) HOCH2C*HOH +H#

  12. Summary of model of DMO hydrogenation Control step ① DMO adsorption DMO dissociative adsorption ② H2 adsorption ③ Surface reaction7 kinds 23 kinds ④adsorption/desorption of intermediate-MG ① ester adsorption H2 molecular adsorption ② H2 adsorption ③ Surface reaction 4 kinds DMO molecular adsorption H2 dissociative adsorption ① ester adsorption ② H2 adsorption ③ Surface reaction 4 kinds

  13. Catalytic performance 表1 25/27日催化剂评价表 表2 设备维修前下催化剂评价表

  14. Catalytic performance on No.3 reactor

  15. Work plan 1.Finish the work about elimination of External/ Internal Diffusion effects 2. Measure the intrinsic reaction rate and select the most possible model. ①. Reaction rate and adsorption equilibrium constant must higher than > 0; ② Activation energy can not be below zero. ③ Reaction rate constant and adsorption equilibrium constant must satisfy the Arrhenius and Van’t Hoff equation; ④ A close correlation with experiment data. 3. Think about further verification of mechanism after kinetics experiment.

  16. Key Laboratory for Green Chemical Technology of Ministry of Education Thanks for Your Attention! Qs & As