Coverage dependence sign(s) incorrect in surface kinetics library?
rwest opened this issue · 2 comments
In /input/kinetics/libraries/Surface/CPOX_Pt/Deutschmann2006_adjusted
we have
entry(
index = 30,
label = "H2OX + OX <=> HOX + HOX",
kinetics = SurfaceArrhenius(
A=(1.0E20, 'cm^2/(mol*s)'),
n = 0,
Ea=(90500, 'J/mol'),
Tmin = (200, 'K'),
Tmax = (3000, 'K'),
coverage_dependence = {'OX': {'a': 0.0, 'm': 0.0, 'E': (-240580, 'J/mol')}},
),
shortDesc = u"""Default""",
longDesc = u"""R30. H2OX is vdW H2O. Ea raised from 43.1 to 90.5 kJ/mol to
match endothermicity of reaction.""",
metal = "Pt",
)
note the coverage dependence term which (unless I'm mistaken?) REDUCES the activation energy as the coverage of O increases.
Compare that with the source
https://www.detchem.com/public/files/mechanisms/11_CH4_O2_ReducedGas_Quiceno2006/sm_CH4_O2_Ptwire_2006_chemkin.txt
which has
O_Pt + H2O_Pt => OH_Pt + OH_Pt 1.000E+20 0.000 43.100
COV / O_Pt 0.000E+00 0.000 240.580 /
which INCREASES the activation energy as the coverage of O increases.
(This increasing the E with O coverage may also reduce the need for your ad hoc adjustment of +47.4 kJ/mol to the barrier, to match the endothermicity. It would balance it as soon as you reached 20% O coverage. Perhaps we should keep a "non-adjusted" version of Deutschmann's model too? )
@mazeau please could you double-check all the other values for their signs.
just double checked it, and that's the only one with the inverse sign. thanks for catching this. I will open a PR
Please could you comment on this bit:
(This increasing the E with O coverage may also reduce the need for your ad hoc adjustment of +47.4 kJ/mol to the barrier, to match the endothermicity. It would balance it as soon as you reached 20% O coverage. Perhaps we should keep a "non-adjusted" version of Deutschmann's model too? )
and then perhaps close this issue if it is fully addressed by #520?