Catalytic oxidation of natural gas over supported platinum: Flow reactor experiments and detailed numberical modeling

Bond, Tami C.; Noguchi, Byan A.; Chou, Chen Pang; Mongia, Rajiv; Chen, Jyh-Yuan; Dibble, Robert W.

doi:10.1016/s0082-0784(96)80403-6

Cited by 36 publications

(53 citation statements)

References 15 publications

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“…The pressure was atmospheric and the Reynolds number based on the incoming mean properties and the hydraulic diameter of the channel (2H) was about 11 500. The channel walls were considered to be coated with platinum and their temperature was fixed to 1220 K. The catalyst site density (G) was taken 2.7×10 −8 kmol/m 2 simulating polycrystalline platinum as in [19]. The fuel-to-air equivalence ratio was varied between 0.215 and 0.240.…”

Section: Channel Geometry and Flow Conditionsmentioning

confidence: 99%

Numerical modelling of turbulent catalytically stabilized channel flow combustion

et al. 2000

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The turbulent catalytically stabilized combustion of lean hydrogen-air premixtures is investigated numerically in plane channels with platinum-coated isothermal walls. The catalytic wall temperature is 1220 K and the incoming mixture has a mean velocity of 15 m/s and a turbulent kinetic energy of 1.5 m 2 /s 2 . A two-dimensional elliptic model is developed with elementary heterogeneous and homogeneous chemical reactions. The approach is based on a two-layer k-ε model of turbulence, a Favre-average moment closure, a presumed-shape (Gaussian) probability density function for gaseous reactions, and a laminar-like closure for surface reactions. Gaseous combustion is confined close to the catalyst surface due to the diffusional imbalance of the limiting reactant (hydrogen). In addition, the peak rms temperature and species fluctuations are always located outside the extent of the homogeneous reaction zone indicating that thermochemical fluctuations have no significant influence on gaseous combustion. Turbulence is significantly suppressed by gaseous combustion resulting in higher turbulent transport for the leaner mixtures, a successive push of the gaseous reaction zone towards the wall, incomplete combustion, and subsequent catalytic conversion of the leaked fuel. Comparison between turbulent and laminar cases having the same incoming properties shows that turbulence inhibits homogeneous ignition due to increased heat transport away from the near-wall layer.

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Section: Channel Geometry and Flow Conditionsmentioning

confidence: 99%

Numerical modelling of turbulent catalytically stabilized channel flow combustion

et al. 2000

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“…The inner horizontal channel surfaces contain Pt on a Al 2 O 3 washcoat. The site density (⌫) for this technical catalyst was taken as 2.7 ϫ 10 Ϫ9 moles/cm 2 , as in Bond et al [17]. Onedimensional heat conduction in the solid plates (crucial for the onset of heterogeneous ignition) was considered; the thermal conductivity (k c ) of the solid plates was taken as 1 W/mK, corresponding to a typical cordierite support material.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional modelling for catalytically stabilized combustion of a lean methane-air mixture with elementary homogeneous and heterogeneous chemical reactions

Dogwiler

Benz

Mantzaras

1999

Combustion and Flame

113

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The catalytically stabilized combustion (CST) of a lean (equivalence ratio ⌽ ϭ 0.4) methane-air mixture was investigated numerically in a laminar channel flow configuration established between two platinum-coated parallel plates 50 mm long and 2 mm apart. A two-dimensional elliptic fluid mechanical model was used, which included elementary reactions for both gaseous and surface chemistry. Heat conduction in the solid plates and radiative heat transfer from the hot catalytic surfaces were accounted for in the model. Heterogeneous ignition occurs just downstream of the channel entrance, at a streamwise distance ( x) of 4 mm. Sensitivity analysis shows that key surface reactions influencing heterogeneous ignition are the adsorption of CH 4 and O 2 and the recombinative desorption of surface-bound O radicals; the adsorption or desorption of radicals other than O has no effect on the heterogeneous ignition location and the concentrations of major species around it. Homogeneous ignition takes place at x ϭ 41 mm. Sensitivity analysis shows that key surface reactions controlling homogeneous ignition are the adsorption/desorption of the OH radical and the adsorption/ desorption of H 2 O, the latter due to its direct influence on the OH production path. In addition, the slope of the OH lateral wall gradient changes from negative (net-desorptive) to positive (net-adsorptive) well before homogeneous ignition ( x ϭ 30 mm), thus exemplifying the importance of a detailed surface chemistry scheme in accurately predicting the homogeneous ignition location. The effect of product formation on homogeneous ignition was studied by varying the third body efficiency of H 2 O. Product formation promotes homogeneous ignition due to a shift in the relative importance of the reactions H ϩ O 2 ϩ M 3 HO 2 ϩ M and HCO ϩ M 3 CO ϩ H ϩ M.

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“…walls. Experimental measurements Bond et al, 1996 con-firm an adiabatic temperature following the conversion increase.…”

Section: Description Of the Single-channel Modelmentioning

confidence: 86%

“…The maximum value reached by Re in the Ž . simulation of experimental data Bond et al, 1996 was less than 160.…”

Section: Description Of the Single-channel Modelmentioning

confidence: 90%

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CFD simulation of reactive flows: Catalytic combustion in a monolith

Canu

Vecchi

2002

AIChE Journal

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Catalytic oxidation of natural gas over supported platinum: Flow reactor experiments and detailed numberical modeling

Cited by 36 publications

References 15 publications

Numerical modelling of turbulent catalytically stabilized channel flow combustion

Numerical modelling of turbulent catalytically stabilized channel flow combustion

Two-dimensional modelling for catalytically stabilized combustion of a lean methane-air mixture with elementary homogeneous and heterogeneous chemical reactions

CFD simulation of reactive flows: Catalytic combustion in a monolith

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