Partial catalytic oxidation of methane to synthesis gas over rhodium: in situ Raman experiments and detailed simulations

Appel, Christoph; Mantzaras, John; Schaeren, Rolf; Bombach, Rolf; Inauen, Andreas; Tylli, Niclas; Wolf, M.; Griffin, Timothy; Winkler, D.; Carroni, Richard

doi:10.1016/j.proci.2004.08.055

Cited by 48 publications

(52 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The attained superadiabatic temperatures in Figure 8.5 are below 1200 K and can still be tolerated by the catalyst/reactor structure. In CPO of CH 4 /air mixtures without exhaust gas dilution, however, the lower heat capacity of nitrogen results in surface temperatures exceeding the adiabatic equilibrium temperature by as much as 400 K [28]. Safe operation requires, as in the case of diffusionally imbalanced mixtures discussed before, passive cooling with an alternately-coated honeycomb structure.…”

Section: 21 Reactor Thermal Managementmentioning

confidence: 99%

See 1 more Smart Citation

Hetero‐/Homogeneous Combustion

Mantzaras

2010

Handbook of Combustion

Self Cite

View full text Add to dashboard Cite

The sections in this article are Introduction Fundamentals of Catalytic Combustion Reactor Thermal Management Hetero‐/Homogeneous Combustion in Power Generation Hetero‐/Homogeneous Kinetics Fuel‐Lean Methane Combustion on Platinum Catalytic Kinetics Gas‐Phase Kinetics Hetero‐/Homogeneous Chemistry Coupling Fuel‐Lean Hydrogen Combustion on Platinum Fuel‐Rich Methane Combustion on Rhodium Application to Practical Systems Turbulent Hetero‐/Homogeneous Combustion Conclusions Acknowledgments

show abstract

Section: 21 Reactor Thermal Managementmentioning

confidence: 99%

“…The use of both LIF and Raman measurements is essential for the validation of gasphase reaction schemes [9,10,17,21,28]. An evaluation of the catalytic processes preceding the onset of homogeneous ignition is still necessary, despite the validation of the catalytic scheme [23] in the preceding section.…”

Section: Gas-phase Kineticsmentioning

confidence: 99%

Hetero‐/Homogeneous Combustion

Mantzaras

2010

Handbook of Combustion

Self Cite

View full text Add to dashboard Cite

show abstract

“…lower combustion temperatures. Depending on the employed power generation cycle, the fuel can either be syngas with varying H 2 =CO composition, or a mixture of syngas and natural gas diluted with total oxidation products (Griffin et al, 2004;Appel et al, 2005a;Eriksson et al, 2006). Catalytic combustion is an option for all the aforementioned fuels and especially for those cycles involving large EGR due to the resulting low gas-phase reactivity and moderate combustion temperatures of the diluted reaction mixtures.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Combustion Of Syngas

Mantzaras¹

2009

Synthesis Gas Combustion

Self Cite

View full text Add to dashboard Cite

The catalytic combustion of syngas/air mixtures over Pt has been investigated numerically in a channel-flow configuration using 2D steady and transient computer codes with detailed hetero-/homogeneous chemistry, transport, and heat transfer mechanisms in the solid. Simulations were carried out for syngas compositions with varying H 2 and CO contents, pressures of 1 to 15 bar, and linear velocities relevant to power generation systems. It is shown that the homogeneous (gas-phase) chemistry of both H 2 and CO cannot be neglected at elevated pressures, even at the very large geometrical confinements relevant to practical catalytic reactors. The diffusional imbalance of hydrogen can lead, depending on its content in the syngas, to superadiabatic surface temperatures that may endanger the catalyst and reactor integrity. On the other hand, the presence of gas-phase H 2 combustion moderates the superadiabatic wall temperatures by shielding the catalyst from the hydrogen-rich channel core. Above a transition temperature of about 700 K, which is roughly independent of pressure and syngas composition, the heterogeneous (catalytic) pathways of CO and H 2 are decoupled, while the chemical interactions between the heterogeneous pathway of each individual fuel component with the homogeneous pathway of the other are minimal. Below the aforementioned transition temperature the catalyst is covered predominantly by CO, which in turn inhibits the catalytic conversion of both fuel components. While the addition of carbon monoxide in hydrogen hinders the catalytic ignition of the latter, there is no clear improvement in the ignition characteristics of CO by adding H 2 . Strategies for reactor thermal management are finally outlined in light of the attained superadiabatic surface temperatures of hydrogen-rich syngas fuels.

show abstract

“…The latter work (Reinke et al, 2004) demonstrated the validity of the heterogeneous reaction scheme of Deutschmann et al (2000) for the complete oxidation of fuel-lean CH 4 =air mixtures over polycrystalline platinum at 4 bar p 16 bar, and further provided reduced catalytic schemes based on the validated mechanism. Appel et al (2005a) extended the aforementioned methodology to the partial catalytic oxidation of fuel-rich CH 4 =air mixtures to synthesis gas over rhodium at moderate pressures (6 bar). Spatially resolved measurements of species concentrations over a catalyst have also been reported in stagnation-flows: Sidwell et al (2002Sidwell et al ( , 2003 used micro-probe sampling to investigate the catalytic kinetics of methane over hexaaluminates at atmospheric pressure and Taylor et al (2003) applied Raman spectroscopy to assess the performance of various catalytic schemes in the partial oxidation of methane over platinum at 40 mbar.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the near-wall H 2 O and CO 2 measurements complemented-but did not control decisively-the kinetic validation since the formation of those species was directly linked to the consumption of CH 4 in the present complete oxidation studies. This was not, however, the case during partial oxidation (Appel et al, 2005a), where the presence of co-existing or sequential pathways (total and partial oxidation) required determination of all reactants and products.…”

mentioning

confidence: 99%

EFFECTS OF H₂O AND CO₂DILUTION ON THE CATALYTIC AND GAS-PHASE COMBUSTION OF METHANE OVER PLATINUM AT ELEVATED PRESSURES

Reinke

Mantzaras

Bombach

et al. 2007

Combustion Science and Technology

Self Cite

View full text Add to dashboard Cite

The impact of large exhaust gas dilution (up to 59.5% H 2 O and 30.3% CO 2 per vol.) on the heterogeneous (catalytic) and homogeneous (gas-phase) steady combustion of fuel-lean CH 4 =O 2 =N 2 mixtures over platinum has been investigated experimentally and numerically at pressures of 5 to 14 bar. In situ, one-dimensional Raman measurements of major gas-phase species concentrations and planar laser induced fluorescence (LIF) of the OH radical were used to assess the heterogeneous and homogeneous combustion processes, respectively. Comparisons between measurements and and CO 2 dilution. The addition of water inhibits the catalytic reactivity due to the increase in the surface coverage of OH(s) that, in turn, reduces the available free platinum sites. This inhibition has been quantified in terms of operating pressure, temperature, and amount of water dilution through an appropriate one-step catalytic reaction for the complete oxidation of methane. Water promotes chemically the onset of homogeneous ignition, as it directly impacts the radical pool buildup. On the other hand, the chemical effect of CO 2 on either reaction pathway is negligible. The influence of H 2 O and CO 2 dilution to the coupling between the two reaction pathways is elucidated and implications for the application of catalytically stabilized combustion to new power generation cycles with large exhaust gas dilution are addressed.

show abstract

Partial catalytic oxidation of methane to synthesis gas over rhodium: in situ Raman experiments and detailed simulations

Cited by 48 publications

References 14 publications

Hetero‐/Homogeneous Combustion

Hetero‐/Homogeneous Combustion

Catalytic Combustion Of Syngas

EFFECTS OF H₂O AND CO₂DILUTION ON THE CATALYTIC AND GAS-PHASE COMBUSTION OF METHANE OVER PLATINUM AT ELEVATED PRESSURES

Contact Info

Product

Resources

About

Partial catalytic oxidation of methane to synthesis gas over rhodium: in situ Raman experiments and detailed simulations

Cited by 48 publications

References 14 publications

Hetero‐/Homogeneous Combustion

Hetero‐/Homogeneous Combustion

Catalytic Combustion Of Syngas

EFFECTS OF H2O AND CO2DILUTION ON THE CATALYTIC AND GAS-PHASE COMBUSTION OF METHANE OVER PLATINUM AT ELEVATED PRESSURES

Contact Info

Product

Resources

About

EFFECTS OF H₂O AND CO₂DILUTION ON THE CATALYTIC AND GAS-PHASE COMBUSTION OF METHANE OVER PLATINUM AT ELEVATED PRESSURES