This example was modeled also by Quiceno et al. in the following paper: M. Hartmann, L. Maier, H.D.Minh, O. Deutschmann, Catalytic partial oxidation of iso-octane over rhodium catalyst: an experimental, modeling and simulation study, Combustion and Flame 157 (2010) 1771-1782.
The catalytic partial oxidation (CPO) of iso-octane on a rhodium catalyst was numerically studied in a tubular reactor. Due to the simmetry of the system, the simulations were performed on a 2D mesh with 4,000 cells.
The simulations were conducted using a microkinetic description of the heterogeneous reactions (www.detchem.com/mechanisms) with 17 species and 56 reactions. The homogeneous reactions in the gas phase were modelled using a detailed kinetic scheme with 168 species and 5,400 reactions (http://creckmodeling.chem.polimi.it/). The operating conditions are reported in the Table below.
|Inlet temperature||1076 K|
|Inlet velocity||0.90 m/s|
|Wall temperature||1076 K|
|Rh site density||2.49·10-9 mol/cm2|
|Catalytic surface||5 cm-1|
The following Figures reporte the calculated composition. It is pretty evident that the catalytic surface reaction is very fast in the entrance (first 1 mm). Strong back-diffusion of H2 can be observed, which means that diffusion coefficients require to be accurately calculated. Moreover strong radial gradient are present in the first mm of the reactor. The concentration of iC8H18 and O2 on the surface is practically zero, which means that catalytic reactions are mass-transfer limited.
The following Figure report the profiles of adsorbed species on the catalytic wall.