SURFACE MECHANISM FOR TWCC REACTIONS WITH Pt/Rh as catalyst **** ********************************************************************* **** * **** C3H6-NO-CO-CO2-O2 SURFACE MECHANISM ON Pt/Rh * **** * **** D. Chatterjee, O. Deutschmann, J. Warnatz * **** Heidelberg University, Germany * **** Contact: O. Deutschmann, mail@detchem.com * **** * **** * **** Reference: * **** (1) D. Chatterjee, O. Deutschmann, J. Warnatz. * **** Detailed surface reaction mechanism in a three-way * **** catalyst. Faraday Discussions 119 (2001) 371-384 * **** * **** * **** DETCHEM format * **** * **** for details see DETCHEM manual (www.detchem.com) * **** * **** * **** Kinetic data: * **** k = A * T**b * exp (-Ea/RT) A b Ea * **** (cm,mol,s) - kJ/mol * **** * **** STICK: A in next reaction is initial sticking coefficient * **** * **** $.. : additional coverage dependence of Ea (3rd column) * **** or changed reaction order (2nd column) * **** * **** Notes: * **** * **** There are three different kinds of adsorption sites: * **** PT(S) nucleophilic = (S) * **** PT(S) electrophilic = (S2) * **** Rh(S) = Rh * **** The total surface is made of 75% Pt and 25% Rh, i.e. * **** the initial coverage must be 0.75 PT(S) and 0.25 RH(S). * **** * **** The mechanism is valid only for this Pt/Rh ratio!!! * **** In particular, the coverage dependent activation energies * **** are scaled for that ratio! * **** * **** * ********************************************************************* **** C3H6/O2/Pt Subsystem * ********************************************************************* ********************************************************************* **** 1. ADSORPTION ********************************************************************* STICK O2 +PT(S) +PT(S) >O(S) +O(S) * 7.000E-02 0.0 0.0 STICK C3H6 +PT(S) +PT(S) >C3H6(S) * 9.800E-01 0.0 0.0 STICK C3H6 +O(S) +PT(S) >C3H5(S2)+OH(S) * 5.000E-02 0.0 0.0 $PT(S) 0.0 -0.9 0.0 STICK H2 +PT(S) +PT(S) >H(S) +H(S) * 4.600E-02 0.0 0.0 $PT(S) 0.0 -1.0 0.0 STICK H2O +PT(S) >H2O(S) * 7.500E-01 0.0 0.0 STICK CO2 +PT(S) >CO2(S) * 5.000E-03 0.0 0.0 STICK CO +PT(S) >CO(S) * 8.400E-01 0.0 0.0 ********************************************************************* **** 2. DESORPTION ********************************************************************* O(S) +O(S) >O2 +PT(S) +PT(S) * 3.700E+21 0.0 232.2 $O(S) 0.0 0.0 90.0 C3H6(S) >C3H6 +PT(S) +PT(S) * 1.000E+13 0.0 72.7 C3H5(S2)+OH(S) >C3H6 +O(S) +PT(S) * 3.700E+21 0.0 31.0 H(S) +H(S) >H2 +PT(S) +PT(S) * 3.700E+21 0.0 67.4 $H(S) 0.0 0.0 6.0 H2O(S) >PT(S) +H2O * 1.000E+13 0.0 40.3 CO(S) >CO +PT(S) * 1.000E+13 0.0 136.4 $CO(S) 0.0 0.0 33.0 CO2(S) >CO2 +PT(S) * 1.000E+13 0.0 27.1 ********************************************************************* **** 3. SURFACE REACTION ********************************************************************* **** 3.1 C3H5(S2) oxidation ********************************************************************* C3H5(S2)+O(S) >C3H4(S2)+OH(S) * 3.700E+21 0.0 95.0 C3H4(S2)+O(S) >C3H3(S2)+OH(S) * 3.700E+21 0.0 00.0 C3H3(S2)+O(S) >C2H2(S2)+CHO(S) * 1.360E+40 0.0 00.0 CHO(S) +PT(S) >OH(S) +C(S) * 1.360E+40 0.0 00.0 C2H2(S2)+O(S) >CHO(S) +CH(S2) * 1.360E+40 0.0 00.0 CH(S2) +O(S) >OH(S) +C(S) * 3.700E+40 0.0 00.0 ********************************************************************* **** 3.2 C3H6(S) decomposition ********************************************************************* C3H6(S) >C3H5(S) +H(S) * 1.000E+13 0.0 75.4 C3H5(S) +H(S) >C3H6(S) * 3.700E+21 0.0 48.8 C3H5(S) +PT(S) >C2H3(S) +CH2(S) * 3.700E+21 0.0 108.2 C2H3(S) +CH2(S) >C3H5(S) +PT(S) * 3.700E+21 0.0 3.2 C2H3(S) +PT(S) >CH3(S) +C(S) * 3.700E+21 0.0 46.0 CH3(S) +C(S) >C2H3(S) +PT(S) * 3.700E+21 0.0 46.9 ********************************************************************* **** 3.3 CHx decomposition ********************************************************************* CH3(S) +PT(S) >CH2(S) +H(S) * 1.262E+22 0.0 70.4 CH2(S) +H(S) >CH3(S) +PT(S) * 3.090E+22 0.0 0.0 CH2(S) +PT(S) >CH(S) +H(S) * 7.000E+22 0.0 59.2 CH(S) +H(S) >CH2(S) +PT(S) * 3.090E+22 0.0 0.0 CH(S) +PT(S) >C(S) +H(S) * 3.090E+22 0.0 0.0 C(S) +H(S) >CH(S) +PT(S) * 1.250E+22 0.0 138.0 ********************************************************************* **** 3.4 C2Hx oxidation ********************************************************************* C2H3(S) +O(S) >C2H3O(S)+PT(S) * 3.700E+19 0.0 62.3 C2H3O(S)+PT(S) >C2H3(S) +O(S) * 3.700E+21 0.0 196.7 $O(S) 0.0 0.0 -45.0 ********************************************************************* **** 3.5 CHx oxidation ********************************************************************* CH3(S) +CO(S) >C2H3O(S)+PT(S) * 3.700E+21 0.0 82.9 C2H3O(S)+PT(S) >CH3(S) +CO(S) * 3.700E+21 0.0 0.0 $CO(S) 0.0 0.0 -33.0 CH3(S) +O(S) >CH2(S) +OH(S) * 3.700E+21 0.0 36.6 CH2(S) +OH(S) >CH3(S) +O(S) * 3.700E+21 0.0 25.1 CH2(S) +O(S) >CH(S) +OH(S) * 3.700E+21 0.0 25.1 CH(S) +OH(S) >CH2(S) +O(S) * 3.700E+21 0.0 25.2 CH(S) +O(S) >C(S) +OH(S) * 3.700E+21 0.0 25.1 C(S) +OH(S) >CH(S) +O(S) * 3.700E+21 0.0 224.8 ********************************************************************* **** 4. H, OH ,H2O SURFACE REACTIONS ********************************************************************* O(S) +H(S) >OH(S) +PT(S) * 3.700E+21 0.0 11.5 OH(S) +PT(S) >O(S) +H(S) * 5.770E+22 0.0 74.9 H(S) +OH(S) >H2O(S) +PT(S) * 3.700E+21 0.0 17.4 H2O(S) +PT(S) >H(S) +OH(S) * 3.660E+21 0.0 73.6 OH(S) +OH(S) >H2O(S) +O(S) * 3.700E+21 0.0 48.2 H2O(S) +O(S) >OH(S) +OH(S) * 2.350E+20 0.0 41.0 **** 5. C oxidation CO(S) +O(S) >CO2(S) +PT(S) * 3.700E+20 0.0 108.0 $CO(S) 0.0 0.0 33.0 $NO(S) 0.0 0.0 -90.0 CO2(S) +PT(S) >CO(S) +O(S) * 3.700E+21 0.0 165.1 $O(S) 0.0 0.0 -45.0 C(S) +O(S) >CO(S) +PT(S) * 3.700E+21 0.0 0.0 $CO(S) 0.0 0.0 -33.0 CO(S) +PT(S) >C(S) +O(S) * 3.700E+21 0.0 218.5 $O(S) 0.0 0.0 -45.0 ********************************************************************* **** NO//Pt Subsystem * ********************************************************************* **** 1. ADSORPTION ********************************************************************* STICK NO +PT(S) >NO(S) * 8.500E-01 0.0 0.0 ********************************************************************* **** 2. DESORPTION ********************************************************************* NO(S) >NO +PT(S) * 1.000E+16 0.0 140.0 N(S) +N(S) >N2 +PT(S) +PT(S) * 3.700E+21 0.0 113.9 $CO(S) 0.0 0.0 75.0 ********************************************************************* **** 3. SURFACE REACTION ********************************************************************* NO(S) +PT(S) >N(S) +O(S) * 5.000E+20 0.0 107.8 $CO(S) 0.0 0.0 -3.0 N(S) +O(S) >NO(S) +PT(S) * 3.700E+21 0.0 128.1 $O(S) 0.0 0.0 45.0 ********************************************************************* **** NO/CO/CO2/Rh Subsystem * ********************************************************************* **** 1. ADSORPTION ********************************************************************* STICK O2 +Rh(S) +Rh(S) >O(Rh) +O(Rh) * 1.000E-02 0.0 0.0 $Rh(S) 0.0 -1.0 0.0 STICK CO +Rh(S) >CO(Rh) * 5.000E-01 0.0 0.0 STICK NO +Rh(S) >NO(Rh) * 5.000E-01 0.0 0.0 ********************************************************************* **** 2. DESORPTION ********************************************************************* O(Rh) +O(Rh) >O2 +Rh(S) +Rh(S) * 3.000E+21 0.0 293.3 CO(Rh) >CO +Rh(S) * 1.000E+14 0.0 132.3 $N(Rh) 0.0 0.0 41.9 $CO(Rh) 0.0 0.0 18.8 NO(Rh) >NO +Rh(S) * 5.000E+13 0.0 108.9 N(Rh) +N(Rh) >N2 +Rh(S) +Rh(S) * 1.110E+19 0.0 136.9 $N(Rh) 0.0 0.0 16.7 ********************************************************************* **** 3. SURFACE REACTION ********************************************************************* **** 3.1 CO(Rh) OXIDATION ********************************************************************* CO(Rh) +O(Rh) >CO2 +Rh(S) +Rh(S) * 3.700E+20 0.0 59.9 ********************************************************************* **** 3.2 NO(Rh) SURFACE REACTION ********************************************************************* NO(Rh) +Rh(S) >N(Rh) +O(Rh) * 2.220E+22 0.0 79.5 ********************************************************************* END ======================================================================