# # SURFACE MECHANISM OF POX of CH4 on PT wire gauze # #*********************************************************************** #**** * #**** CH4-O2 SURFACE MECHANISM ON PT * #**** * #**** Version 1.0 Spring 2005 * #**** * #**** Raul Quiceno, Olaf Deutschmann, IWR, Heidelberg University, * #**** Germany * #**** Contact: mail@detchem.com (O. Deutschmann) * #**** * #**** Reference: * #**** R. Quiceno, J. Perez-Ramyrez, J. Warnatz, O. Deutschmann. * #**** Appl. Catal. A: General (2006) * #**** www.detchem.com/mechanisms * #**** * #**** * #**** The kinetic data of the backward reactions of * #**** reactions in Section 3 are calculated * #**** from thermodynamics (k_b = k_f /K) * #**** * #**** Surface site density: 2.72E-9 mol/cm**2 * #**** * #---------------------------------------------------------------------- units(length = "cm", time = "s", quantity = "mol", act_energy = "J/mol") # # Define a gas mixture. This contains only major species, and no # gas-phase reactions. # ideal_gas(name = "gas", elements = "O H C N Ar", species = """H2 O2 H2O CH4 CO CO2 AR""", options = ['skip_undeclared_elements', 'skip_undeclared_species'], initial_state = state(temperature = 300.0, pressure = OneAtm, mole_fractions = 'CH4:0.095, O2:0.21, AR:0.79') ) # # The platinum surface. ideal_interface(name = "Pt_surf", elements = " Pt H O C ", species = """ PT(S) H(S) H2O(S) OH(S) CO(S) CO2(S) CH3(S) CH2(S) CH(S) C(S) O(S) """, phases = "gas", site_density = 2.72e-9, reactions = "all", options = ['skip_undeclared_elements', 'skip_undeclared_species'], initial_state = state(temperature = 900.0, coverages = 'O(S):0.00, PT(S):0.01, H(S):0.99') ) #------------------------------------------------------------------------------- # Species data #------------------------------------------------------------------------------- species(name = "CH4", atoms = " C:1 H:4 ", thermo = ( NASA( [ 300.00, 1000.00], [ 7.787414790E-01, 1.747668350E-02, -2.783409040E-05, 3.049708040E-08, -1.223930680E-11, -9.825228520E+03, 1.372219470E+01] ), NASA( [ 1000.00, 5000.00], [ 1.683478830E+00, 1.023723560E-02, -3.875128640E-06, 6.785584870E-10, -4.503423120E-14, -1.008078710E+04, 9.623394970E+00] ) ) ) species(name = "O2", atoms = " O:2 ", thermo = ( NASA( [ 300.00, 1000.00], [ 3.783713500E+00, -3.023363400E-03, 9.949275100E-06, -9.818910100E-09, 3.303182500E-12, -1.063810700E+03, 3.641634500E+00] ), NASA( [ 1000.00, 5000.00], [ 3.612213900E+00, 7.485316600E-04, -1.982064700E-07, 3.374900800E-11, -2.390737400E-15, -1.197815100E+03, 3.670330700E+00] ) ) ) species(name = "CO", atoms = " C:1 O:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ 3.262451650E+00, 1.511940850E-03, -3.881755220E-06, 5.581944240E-09, -2.474951230E-12, -1.431053910E+04, 4.848896980E+00] ), NASA( [ 1000.00, 5000.00], [ 3.025078060E+00, 1.442688520E-03, -5.630827790E-07, 1.018581330E-10, -6.910951560E-15, -1.426834960E+04, 6.108217720E+00] ) ) ) species(name = "CO2", atoms = " C:1 O:2 ", thermo = ( NASA( [ 300.00, 1000.00], [ 2.275724650E+00, 9.922072290E-03, -1.040911320E-05, 6.866686780E-09, -2.117280090E-12, -4.837314060E+04, 1.018848800E+01] ), NASA( [ 1000.00, 5000.00], [ 4.453622820E+00, 3.140168730E-03, -1.278410540E-06, 2.393996670E-10, -1.669033190E-14, -4.896696090E+04, -9.553958770E-01] ) ) ) species(name = "H2", atoms = " H:2 ", thermo = ( NASA( [ 300.00, 1000.00], [ 3.355351400E+00, 5.013614400E-04, -2.300690800E-07, -4.790532400E-10, 4.852258500E-13, -1.019162600E+03, -3.547722800E+00] ), NASA( [ 1000.00, 5000.00], [ 3.066709500E+00, 5.747375500E-04, 1.393831900E-08, -2.548351800E-11, 2.909857400E-15, -8.654741200E+02, -1.779842400E+00] ) ) ) species(name = "H2O", atoms = " H:2 O:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ 4.167723400E+00, -1.811497000E-03, 5.947128800E-06, -4.869202100E-09, 1.529199100E-12, -3.028996900E+04, -7.313547400E-01] ), NASA( [ 1000.00, 5000.00], [ 2.611047200E+00, 3.156313000E-03, -9.298543800E-07, 1.333153800E-10, -7.468935100E-15, -2.986816700E+04, 7.209126800E+00] ) ) ) species(name = "AR", atoms = " Ar:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ 2.500000000E+00, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, -7.453749800E+02, 4.366000600E+00] ), NASA( [ 1000.00, 5000.00], [ 2.500000000E+00, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, -7.453750200E+02, 4.366000600E+00] ) ) ) species(name = "PT(S)", atoms = " Pt:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00] ), NASA( [ 1000.00, 3000.00], [ 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00] ) ) ) species(name = "H(S)", atoms = " H:1 Pt:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ -1.302987700E+00, 5.417319900E-03, 3.127797200E-07, -3.232853300E-09, 1.136282000E-12, -4.227707500E+03, 5.874323800E+00] ), NASA( [ 1000.00, 3000.00], [ 1.069699600E+00, 1.543223000E-03, -1.550092200E-07, -1.657316500E-10, 3.835934700E-14, -5.054612800E+03, -7.155523800E+00] ) ) ) species(name = "H2O(S)", atoms = " O:1 H:2 Pt:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ -2.765155300E+00, 1.331511500E-02, 1.012769500E-06, -7.182008300E-09, 2.281377600E-12, -3.639805500E+04, 1.209814500E+01] ), NASA( [ 1000.00, 3000.00], [ 2.580305100E+00, 4.957082700E-03, -4.689405600E-07, -5.263313700E-10, 1.199832200E-13, -3.830223400E+04, -1.740632200E+01] ) ) ) species(name = "OH(S)", atoms = " O:1 H:1 Pt:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ -2.034088100E+00, 9.366268300E-03, 6.627521400E-07, -5.207488700E-09, 1.708873500E-12, -2.531994900E+04, 8.986318600E+00] ), NASA( [ 1000.00, 3000.00], [ 1.824997300E+00, 3.250156500E-03, -3.119754100E-07, -3.460320600E-10, 7.917147200E-14, -2.668549200E+04, -1.228089100E+01] ) ) ) species(name = "CO(S)", atoms = " C:1 O:1 Pt:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ 4.890746600E+00, 6.813423500E-05, 1.976881400E-07, 1.238866900E-09, -9.033924900E-13, -3.229783600E+04, -1.745316100E+01] ), NASA( [ 1000.00, 3000.00], [ 4.708377800E+00, 9.603729700E-04, -1.180527900E-07, -7.688382600E-11, 1.823200000E-14, -3.231172300E+04, -1.671959300E+01] ) ) ) species(name = "CO2(S)", atoms = " C:1 O:2 Pt:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ 4.690000000E-01, 6.266200000E-03, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, -5.045870000E+04, -4.555000000E+00] ), NASA( [ 1000.00, 3000.00], [ 4.690000000E-01, 6.266000000E-03, 0.000000000E+00, 0.000000000E+00, 0.000000000E+00, -5.045870000E+04, -4.555000000E+00] ) ) ) species(name = "CH3(S)", atoms = " C:1 H:3 Pt:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ 1.291921700E+00, 7.267560300E-03, 9.817947600E-07, -2.047129400E-09, 9.083271700E-14, -2.574561000E+03, -1.198303700E+00] ), NASA( [ 1000.00, 3000.00], [ 3.001616500E+00, 5.408450500E-03, -4.053805800E-07, -5.342246600E-10, 1.145188700E-13, -3.275272200E+03, -1.096598400E+01] ) ) ) species(name = "CH2(S)", atoms = " C:1 H:2 Pt:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ -1.487640400E-01, 5.139628900E-03, 1.121107500E-06, -8.275545200E-10, -4.457234500E-13, 1.087870000E+04, 5.745188200E+00] ), NASA( [ 1000.00, 3000.00], [ 7.407612200E-01, 4.803253300E-03, -3.282563300E-07, -4.777978600E-10, 1.007345200E-13, 1.044375200E+04, 4.084208600E-01] ) ) ) species(name = "CH(S)", atoms = " C:1 H:1 Pt:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ 8.415748500E-01, 1.309538000E-03, 2.846457500E-07, 6.386290400E-10, -4.276665800E-13, 2.233280100E+04, 1.145230500E+00] ), NASA( [ 1000.00, 3000.00], [ -4.824247200E-03, 3.044623900E-03, -1.606609900E-07, -2.904170000E-10, 5.799992400E-14, 2.259521900E+04, 5.667781800E+00] ) ) ) species(name = "C(S)", atoms = " C:1 Pt:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ 5.892401900E-01, 2.501284200E-03, -3.422949800E-07, -1.899434600E-09, 1.019040600E-12, 1.023692300E+04, 2.193701700E+00] ), NASA( [ 1000.00, 3000.00], [ 1.579282400E+00, 3.652870100E-04, -5.065767200E-08, -3.488485500E-11, 8.808969900E-15, 9.953575200E+03, -3.024049500E+00] ) ) ) species(name = "O(S)", atoms = " O:1 Pt:1 ", thermo = ( NASA( [ 300.00, 1000.00], [ -9.498690400E-01, 7.404230500E-03, -1.045142400E-06, -6.112042000E-09, 3.378799200E-12, -1.320991200E+04, 3.613790500E+00] ), NASA( [ 1000.00, 3000.00], [ 1.945418000E+00, 9.176164700E-04, -1.122671900E-07, -9.909962400E-11, 2.430769900E-14, -1.400518700E+04, -1.153166300E+01] ) ) ) #------------------------------------------------------------------------------- # Reaction data #------------------------------------------------------------------------------- # Adsorption reactions surface_reaction("H2 + 2 PT(S) => 2 H(S)", stick(0.046, 0, 0, coverage = ['PT(S)',0.0, -1.0, 0.0])) surface_reaction( "O2 + 2 PT(S) => 2 O(S)", Arrhenius(1.89000E+21, -0.5, 0)) surface_reaction( "CH4 + 2 PT(S) => CH3(S) + H(S)", stick(0.0009, 0.0, 72000.0)) surface_reaction( "CH4 + PT(S) + O(S) => CH3(S) + OH(S)", Arrhenius(5.0e18, 0.7, 42000.0, coverage = ['O(S)', 0.0, 0.0, 8000])) surface_reaction( "CH4 + PT(S) + OH(S) => CH3(S) + H2O(S)", stick(1.0, 0.0, 10000.0)) surface_reaction( "H2O + PT(S) => H2O(S)", stick(7.50000E-01, 0, 0)) surface_reaction( "CO2 + PT(S) => CO2(S)", stick(0.005, 0, 0)) surface_reaction( "CO + PT(S) => CO(S)", stick(0.84, 0, 0)) # Desorption reactions surface_reaction( "2 H(S) => H2 + 2 PT(S)", Arrhenius(3.70000E+21, 0, 67400, coverage = ['H(S)', 0.0, 0.0, -10000.0])) surface_reaction( "2 O(S) => O2 + 2 PT(S)", Arrhenius(3.70000E+21, 0, 235500, coverage = ['O(S)', 0.0, 0.0, -188300.0]) ) surface_reaction( "H2O(S) => H2O + PT(S)", [4.50000E+12, 0, 41800]) surface_reaction( "CO(S) => CO + PT(S)", Arrhenius(1.00000E+15, 0, 146000, coverage = ['CO(S)', 0.0, 0.0, -33000.0])) surface_reaction( "CO2(S) => CO2 + PT(S)", [1.00000E+13, 0, 27100]) # surface reactions surface_reaction( "C(S) + O(S) => CO(S) + PT(S)", [3.70000E+19, 0, 0]) surface_reaction( "CO(S) + PT(S) => C(S) + O(S)", Arrhenius(3.70000E+19, 0, 236500, coverage = ['CO(S)', 0.0, 0.0, -33000])) # error in paper. This reaction is consistent with the version in the # file on the DETCHEM mechanisms web site, but differs from the # version in the Applied Catalysis paper. surface_reaction( "CO(S) + O(S) => CO2(S) + PT(S)", Arrhenius(3.70000E+21, 0, 117600, coverage = ['CO(S)', 0.0, 0.0, -33000])) # minor diff w paper surface_reaction( "CO2(S) + PT(S) => CO(S) + O(S)", Arrhenius(3.70000E+19, 0, 173300, coverage = ['O(S)', 0.0, 0.0, 94100])) surface_reaction( "CO(S) + OH(S) => CO2(S) + H(S)", Arrhenius(1.0000E+19, 0, 38700, coverage = ['CO(S)', 0.0, 0.0, -30000])) surface_reaction( "CO2(S) + H(S) => CO(S) + OH(S)", Arrhenius(1.0000E+19, 0, 8400)) surface_reaction( "CH3(S) + PT(S) => CH2(S) + H(S)", Arrhenius(1.2600E+22, 0, 70300)) surface_reaction( "CH2(S) + H(S) => CH3(S) + PT(S)", Arrhenius(3.0900E+22, 0, 0, coverage = ['H(S)', 0.0, 0.0, -2800])) surface_reaction( "CH2(S) + PT(S) => CH(S) + H(S)", Arrhenius(7.3100E+22, 0, 58900, coverage = ['C(S)', 0.0, 0.0, 50000])) surface_reaction( "CH(S) + H(S) => CH2(S) + PT(S)", Arrhenius(3.0900E+22, 0, 0, coverage = ['H(S)', 0.0, 0.0, -2800])) surface_reaction( "CH(S) + PT(S) => C(S) + H(S)", Arrhenius(3.0900E+22, 0, 0, coverage = ['H(S)', 0.0, 0.0, -2800])) surface_reaction( "C(S) + H(S) => CH(S) + PT(S)", Arrhenius(1.2500E+22, 0, 138000)) surface_reaction( "H(S) + O(S) => OH(S) + PT(S)", Arrhenius(1.2800E+21, 0, 11200)) surface_reaction( "OH(S) + PT(S) => H(S) + O(S)", Arrhenius(7.39e19, 0, 77300, coverage = ['O(S)', 0.0, 0.0, -73200])) surface_reaction( "H2O(S) + PT(S) => H(S) + OH(S)", Arrhenius(1.15e19, 0, 101400, coverage = ['O(S)', 0.0, 0.0, 167300])) surface_reaction( "2 OH(S) => H2O(S) + O(S)", Arrhenius(7.4e20, 0, 74000)) surface_reaction( "H2O(S) + O(S) => 2 OH(S)", Arrhenius(1.0e20, 0, 43100, coverage = ['O(S)', 0.0, 0.0, 240600])) surface_reaction( "H2 + C(S) => CH2(S)", stick(0.04, 0, 29700, coverage = ['C(S)', 0.0, 0.0, 4600])) surface_reaction( "CH2(S) => C(S) + H2", Arrhenius(7.69e13, 0, 25100, coverage = ['C(S)', 0.0, 0.0, 50000])) surface_reaction( "H(S) + OH(S) => H2O(S) + PT(S)", Arrhenius(2.04e21, 0, 66220)) surface_reaction( "CH3(S) + H(S) => CH4 + 2 PT(S)", Arrhenius(3.3e21, 0, 50000, coverage = ['H(S)', 0.0, 0.0, -2800])) surface_reaction( "CH3(S) + H2O(S) => CH4 + OH(S) + PT(S)", Arrhenius(3.7e21, 0, 110600)) surface_reaction( "CH3(S) + OH(S) => CH4 + O(S) + PT(S)", Arrhenius(3.7e21, 0, 87900))