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Performance of monolithic catalysts with complex active component in partial oxidation of methane into syngas: experimental studies and modeling
Natural Gas Conversion VIII F.B. Noronha, M. Schmal, E.F. Sousa-Aguiar (Editors) © 2007 Published by Elsevier B.V.
361
Performance of monolithic catalysts with complex active component in partial oxidation of methane into syngas: experimental studies and modeling V. Sadykova, S. Pavlovaa, Z. Vostrikova, N. Sazonovaa, E. Gubanovaa, R. Buninaa, G. Alikinaa, A. Lukashevicha, L. Pinaevaa, L. Gogina, S. Pokrovskayaa, V. Skomorokhova, A. Shigarova, C. Mirodatosb, A. van Veenb, A. Khristolyubovc, V. Ulyanitskiid a
Boreskov Institute of Catalysis SB RAS, pr. Lavrentieva, 5, Novosibirsk, 630090, Russia b Institut de Recherches sur la Catalyse - CNRS, 2 av. Albert Einstein, 69626 Villeurbanne Cedex – France c VNIIEF, Sarov, 607190, Russia. d Lavrentiev Institute of Hydrodynamics, 630090, Novosibirsk, Russia.
1. Introduction Partial oxidation of methane (POM) on monolithic catalysts at short contact times is a promising process for design of compact syngas generators. As was demonstrated for Rh- or Pt- supported catalysts [1-3], optimization of their performance requires process modeling based upon a detailed elementary step reaction mechanism verified for pure metals. For more complex active components such as Pt-promoted LaNiO3 /Ce-Zr-O etc [4], elucidation of such detailed elementary kinetics would require too extensive research. This work presents a verification of more simple approach to modeling of both steadystate and start-up performance based upon using the rate constants for the reactions of methane selective oxidation and reforming reactions estimated for small separate units of monolithic catalysts (channels etc) in nearly isothermal conditions.
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2. Experimental Two types of honeycomb monolithic substrates based on corundum (a hexagonal prism with a side of 40 mm and triangular channels with wall thickness of 0.2– 0.3 mm) or fechraloy foil (cylindrer 50 mm diameter, 200 400 cpsi, 20 μm foil thickness) were used. The metal surface is protected by a thin (~10 μm) nonporous layer of corundum supported by the dust blasting [4]. The active component comprised of mixed LaNiO3/Ce-Zr-La-O oxides (up to 15 wt.%) and Pt (up to 0.5 wt.%) was supported via washcoating and/or impregnation procedures followed by drying and calcination [4]. The monolith catalysts (50 mm length) along with the front and back-end thermal shields (2 cm each) were placed into a tubular stainless-steel reactor. The axial temperature at selected points along the monolith was scanned by thermocouples located in the plugged central channel. The linear velocity of the feed was varied in the range of 0.5-6 m/s. The feed was comprised of natural gas (NG) - 22-29 vol.%, air – balance. To ignite the process, the air-NG mixture preheated up to 400°C was fed to the reactor warmed to the same temperature in air. The gas composition was monitored by GC, MS and IR absorbance gas analyzers. Separate structured elements (triangular channels of corundum monolith, a roll of Fe-Cr gauze (wire diameter 0.2-0.3 mm, square mesh ~ 0.5x0.5 mm, length 10 mm) or a wire spiral (wire diameter 0.5 mm, external spiral diameter 3 mm, length 16 mm) with supported protective corundum sublayer and the same type of mixed active component Pt/LaNiO3/Ce-Zr-La-O were tested in a quartz reactor of 4 mm inner diameter at contact times 1-15 ms using feeds containing 115% of methane and required amount of oxidants (O2, CO2 and H2O) both in the stationary and temperature-programmed modes. Overall loading of active components on the gauze was ~ 5 wt. %, and on spiral ~2 wt. %, i.e. several times smaller than that for corundum channels (~18 wt. % [5]). 3. Modeling Reactor was assumed to be adiabatic and of a plug-flow type. One-dimensional model containing detailed mass and energy balances for the gas phase and the monolithic catalyst [6] was used. The kinetic model of partial methane oxidation includes stages of complete methane oxidation, steam reforming and water gas shift reaction. The rate constants and activation energies for these reactions were estimated from results of isothermal experiments with triangular corundum-based channels using rate equations of the type suggested in [7-9]. In POM modeling, the reaction rates were calculated using the surface concentrations of reagents and the catalyst temperature. A set of non-linear algebraic equations for the gas and surface concentrations of components was solved by a stabilization method. Both steady-state and transient concentration
363
Performance of monolithic catalysts with complex active component
and temperature profiles were obtained and compared with experimental data for the real-size monoliths. 4. Results and discussion 4.1. Performance of separate elements At 600-700 oC for all types of elements, the oxygen in the CH4+O2 feed was not completely consumed. In these conditions a higher CH4 conversion and syngas yield were observed for the corundum-supported element (Fig. 1) with a big loading of the active component distributed within porous walls. This feature can be explained by syngas generation via steam reforming (SR) in pores where O2 is depleted. At high (~900 oC) temperatures where all O2 is consumed in the inlet part of an element, the highest CH4 conversion and syngas yield were obtained for elements on metallic substrates with a low loading of active components comprised of thin (~10 microns) layers This suggests an important role of the heat transfer from the inlet part (where O2 is consumed) into the rear part where endothermic reactions of CH4 reforming occur. Similarly (Fig. 2), a high-temperature performance of the same active component in the CH4 dry reforming (DR) is higher when it is supported onto a gauze, which helps to avoid heat-transfer limitations. When O2 is added to the feed, performance strongly declines for gauze-supported active component due to suppression of CH4 activation. This phenomenon is less strongly expressed for porous corundum-based structural element due to more reduced state of the active component located within pores of substrate. For structural elements based upon corundum channels, rather close rate constants for POM, SR and 2
60 40 20
80
3
2
1 CO selectivity,%
Methane conversion, %
80
60
3
40 20 0
0
600
600
700 800 o Toutlet, C
a
900
700
800
900
o
T, C
b
Fig. 1. CH4 conversion (a) and CO selectivity (b) vs T in POM on spiral (1), gauze (2) and corundum channel-based (3) catalytic elements. Contact time 8 ms, feed 7%CH4 +3.5%O2
1
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V. Sadykov et al. 16
1200
1
ɇ2+ɋɈ,%
4 8 2
4
Temperature, oC
1100
3
12
1000 900
1 2
800
3 4
700 600 5
500
0 600
700 800 o Temperature, C
900
Fig. 2. Syngas content in converted feed vs T for structural elements based upon gauze (1,2) or corundum channel (3, 4) in CH4 DR (1, 3) or oxy-DR (2, 4). Inlet feed 7%ɋɇ4+7%ɋɈ2 (1,3) or 7%ɋɇ4+7%ɋɈ2 + 1.75% O2 (2,4), contact time 8 ms.
0
10
20 30 Length, mm
40
50
Fig. 3. Temperature profiles for monolithic catalysts on corundum (1-4) or fechraloy (5) substrates. Contact time (s): 1-0.02, 2-0.04, 3-0.06, 4-0.1, 5-0.03. 27 % NG in air, no back thermal shield, T at 52 mm measured in the gas phase after monolith.
DR of CH4 were obtained varying in the range of 50-200 s-1 at temperatures in the range of 650-800 oC [5]. Since at temperatures ~ 600 -800oC the mass transfer coefficient for the triangular channel was estimated to be ~ 600-800 c1 , this suggests that for POM the impact of the mass transfer could be appreciable. 4.2. Steady-state performance of monolithic catalysts and its modeling In the autothermal mode, performance of catalysts on corundum and fechraloy foil substrates is practically identical despite a lower content of the active component for the latter case. At the inlet gas temperature of 400°C and the linear velocity in the range of 0.5-2 m/s, methane conversion and CO + H2 yield are nearly constant being equal to ~85-90% and 50-53 vol.%, respectively. These performance characteristics are comparable to those for much more expensive Rh-containing monolithic catalysts [2,3]. No deactivation of performance with time –on-stream was observed.The temperature profiles along the catalyst length (Fig. 3) are rather similar for both types of monolithic substrates. In the narrow inlet part of the monolith highly exothermal reaction of methane combustion occurs leading to a steep rise of temperature. After reaching the maximum at a position depending upon the space velocity (Fig. 3), the temperature of the catalyst declines due to the heat consumption by endothermic steam and dry reforming reactions. The outlet temperature increases with the space velocity reflecting overall increase of the heat generated within the reactor in the nearly adiabatic mode. Less steep temperature profile (from Tmax to Tend) for the catalyst on the fechraloy substrate implies some impact of the heat transfer by conduction along the metal foil. As
365
Performance of monolithic catalysts with complex active component
revealed by modeling (Fig. 4), for the main part of the monolith the catalyst temperature exceeds that of the gas phase thus demonstrating importance of the heat and mass transfer processes. The peak temperature is correctly reproduced only with a due regard for steam reforming occurring even in the presence of gas-phase oxygen, apparently within pores of corundum substrate (vide supra). This reaction is also favored by a big difference between the concentration of reagents (especially, oxygen) in the gas phase and at the surface of the channel due to the effect of the diffusion-controlled mass transfer (Fig. 5). 4.3. Ignition characteristics and their modeling Under conditions of high-temperature POM process, complex perovskite-like LaNi(Pt)O3 oxide is reduced yielding small highly reactive Nio particles promoted by Pt [4,5]. This decreases typical ignition temperature of POM for mildly reoxidized catalyst to ~ 400 oC from 500-600 oC for asprepared sample. Ignition usually starts at some intermediate point within the monolith (Fig. 6). The ignition point moves downstream with decreasing the contact time (increasing space velocity). After ignition, the hot spot moves towards the monolith inlet. Modeling describes reasonably good experimental temperature profiles within the monolith. The peak of deep oxidation products concentration –H2O and CO2 (Fig. 7) is achieved within 30 s from start-up, when the temperature in the middle of monolith increases up to ~ 750 oC. After attainment of the steady-state temperature profile within all monolith, concentration of deep oxidation products decreases and that of CO increases to nearly constant levels, while a slow increase of H2 content continues. This suggests that CO formation is mainly controlled by the primary process of CH4 transformation within the inlet part, while for H2 formation a slower stage of CH4 SR is important as well. These dynamic features agree with those earlier observed for Rh/ alumina monolith [2]. catalyst
Gas velocity = 1.1 m/s CH4=28.5%
0,30
1000
0,25
900
Mole fractions
O
Temperature, C
1100
800
gas
700 600 500
CH4 (surface)
0,20
CH4 (flow)
0,15
O2(surface)
0,10 0,05
400
O2(flow)
0,00 0
300 0
1
2
3
4
5
6
7
1
2
3
4
5
6
7
Length, cm
Length, cm
Fig. 4. Experimental (points) and calculated (line) temperature profiles within the monolithic catalyst and in the gas phase. 28.5% of NG in air, contact time 0.05 s.
Fig. 5. Calculated profiles of gas-phase and surface concentrations of reagents. Contact time 0.05 s, inlet T 370 oC, 28.5% of NG in air.
366 Concentration, % vol.
V. Sadykov et al. H2
40 35 30 25 20 15 10 5 0
CH4
CO2 0
Fig. 6. Comparison of experimental (points) and calculated (lines) dynamics of temperature variation at selected points (1-2, 2-5, 3-10, 425 mm) in monolithic catalyst on corundum substrate during start-up. Contact time 0.11 s, 25.5% NG +15.7 %Ɉ2 in N2
CO
O2
20
40
60 80 time, s
400 500
Fig. 7. Typical dynamics of the concentration of reagents and products variation during start-up for monolithic catalyst on corundum substrate. Start-up by switching the stream of air through catalyst preheated to 400 oC for feed 27% NG in air.
At the same contact time, the temperature profile stabilizes more rapidly for the catalysts based on metallic substrate as compared to corundum ones due to a higher thermal conductivity of the metal foil. 5. Conclusions Experimental studies and modeling demonstrated importance of the heat and mass transfer for the process of the natural gas partial oxidation into syngas at short contact times on monolithic catalysts with a complex active component Pt/LaNiO3/Ce-Zr-La-O. A simplified approach for modeling based upon using rate constants for the reactions of methane transformation into syngas estimated for separate structural elements of monolithic catalysts in nearly isothermal conditions was successfully verified. This work was carried out in frames of European Associated Laboratory on Catalysis. Support by ISTC 2529 Project is gratefully acknowledged. References 1. 2. 3. 4. 5. 6. 7. 8. 9.
G. Veser, J. Frauhammer, Chem. Eng. Sci. 55 (2000) 2271. R. Schwiedernoch, S. Tischer, C. Correa, O. Deutschmann, Chem. Eng. Sci. 58 (2003) 633. R. Horn, K.A. Williams, N.J. Degenstein, L.D. Schmidt, J. Catal. 242 (2006) 92. V.A. Sadykov, S.N. Pavlova et al. Kinetics Catal. 46 (2005) 227. S. Pavlova, N. Sazonova, V. Sadykov, S. Pokrovskaya, V. Kuzmin, G. Alikina, A. Lukashevich, E. Gubanova, Catal. Today 105 (2005) 367. G. Groppi, E. Tronconi, P. Forzatti, Catal. Rev.-Sci. Eng., 41 (1999) 227. D.L. Trimm, C.-W. Lam, Chem. Eng. Sci. 35 (1980) 1405. J.Wei, E. Iglesia, J. Catal., 224 (2004) 370. T. Numaguchi, K. Kikuchi, Chem. Eng. Sci. 43 (1988) 2295.
361
Performance of monolithic catalysts with complex active component in partial oxidation of methane into syngas: experimental studies and modeling V. Sadykova, S. Pavlovaa, Z. Vostrikova, N. Sazonovaa, E. Gubanovaa, R. Buninaa, G. Alikinaa, A. Lukashevicha, L. Pinaevaa, L. Gogina, S. Pokrovskayaa, V. Skomorokhova, A. Shigarova, C. Mirodatosb, A. van Veenb, A. Khristolyubovc, V. Ulyanitskiid a
Boreskov Institute of Catalysis SB RAS, pr. Lavrentieva, 5, Novosibirsk, 630090, Russia b Institut de Recherches sur la Catalyse - CNRS, 2 av. Albert Einstein, 69626 Villeurbanne Cedex – France c VNIIEF, Sarov, 607190, Russia. d Lavrentiev Institute of Hydrodynamics, 630090, Novosibirsk, Russia.
1. Introduction Partial oxidation of methane (POM) on monolithic catalysts at short contact times is a promising process for design of compact syngas generators. As was demonstrated for Rh- or Pt- supported catalysts [1-3], optimization of their performance requires process modeling based upon a detailed elementary step reaction mechanism verified for pure metals. For more complex active components such as Pt-promoted LaNiO3 /Ce-Zr-O etc [4], elucidation of such detailed elementary kinetics would require too extensive research. This work presents a verification of more simple approach to modeling of both steadystate and start-up performance based upon using the rate constants for the reactions of methane selective oxidation and reforming reactions estimated for small separate units of monolithic catalysts (channels etc) in nearly isothermal conditions.
362
V. Sadykov et al.
2. Experimental Two types of honeycomb monolithic substrates based on corundum (a hexagonal prism with a side of 40 mm and triangular channels with wall thickness of 0.2– 0.3 mm) or fechraloy foil (cylindrer 50 mm diameter, 200 400 cpsi, 20 μm foil thickness) were used. The metal surface is protected by a thin (~10 μm) nonporous layer of corundum supported by the dust blasting [4]. The active component comprised of mixed LaNiO3/Ce-Zr-La-O oxides (up to 15 wt.%) and Pt (up to 0.5 wt.%) was supported via washcoating and/or impregnation procedures followed by drying and calcination [4]. The monolith catalysts (50 mm length) along with the front and back-end thermal shields (2 cm each) were placed into a tubular stainless-steel reactor. The axial temperature at selected points along the monolith was scanned by thermocouples located in the plugged central channel. The linear velocity of the feed was varied in the range of 0.5-6 m/s. The feed was comprised of natural gas (NG) - 22-29 vol.%, air – balance. To ignite the process, the air-NG mixture preheated up to 400°C was fed to the reactor warmed to the same temperature in air. The gas composition was monitored by GC, MS and IR absorbance gas analyzers. Separate structured elements (triangular channels of corundum monolith, a roll of Fe-Cr gauze (wire diameter 0.2-0.3 mm, square mesh ~ 0.5x0.5 mm, length 10 mm) or a wire spiral (wire diameter 0.5 mm, external spiral diameter 3 mm, length 16 mm) with supported protective corundum sublayer and the same type of mixed active component Pt/LaNiO3/Ce-Zr-La-O were tested in a quartz reactor of 4 mm inner diameter at contact times 1-15 ms using feeds containing 115% of methane and required amount of oxidants (O2, CO2 and H2O) both in the stationary and temperature-programmed modes. Overall loading of active components on the gauze was ~ 5 wt. %, and on spiral ~2 wt. %, i.e. several times smaller than that for corundum channels (~18 wt. % [5]). 3. Modeling Reactor was assumed to be adiabatic and of a plug-flow type. One-dimensional model containing detailed mass and energy balances for the gas phase and the monolithic catalyst [6] was used. The kinetic model of partial methane oxidation includes stages of complete methane oxidation, steam reforming and water gas shift reaction. The rate constants and activation energies for these reactions were estimated from results of isothermal experiments with triangular corundum-based channels using rate equations of the type suggested in [7-9]. In POM modeling, the reaction rates were calculated using the surface concentrations of reagents and the catalyst temperature. A set of non-linear algebraic equations for the gas and surface concentrations of components was solved by a stabilization method. Both steady-state and transient concentration
363
Performance of monolithic catalysts with complex active component
and temperature profiles were obtained and compared with experimental data for the real-size monoliths. 4. Results and discussion 4.1. Performance of separate elements At 600-700 oC for all types of elements, the oxygen in the CH4+O2 feed was not completely consumed. In these conditions a higher CH4 conversion and syngas yield were observed for the corundum-supported element (Fig. 1) with a big loading of the active component distributed within porous walls. This feature can be explained by syngas generation via steam reforming (SR) in pores where O2 is depleted. At high (~900 oC) temperatures where all O2 is consumed in the inlet part of an element, the highest CH4 conversion and syngas yield were obtained for elements on metallic substrates with a low loading of active components comprised of thin (~10 microns) layers This suggests an important role of the heat transfer from the inlet part (where O2 is consumed) into the rear part where endothermic reactions of CH4 reforming occur. Similarly (Fig. 2), a high-temperature performance of the same active component in the CH4 dry reforming (DR) is higher when it is supported onto a gauze, which helps to avoid heat-transfer limitations. When O2 is added to the feed, performance strongly declines for gauze-supported active component due to suppression of CH4 activation. This phenomenon is less strongly expressed for porous corundum-based structural element due to more reduced state of the active component located within pores of substrate. For structural elements based upon corundum channels, rather close rate constants for POM, SR and 2
60 40 20
80
3
2
1 CO selectivity,%
Methane conversion, %
80
60
3
40 20 0
0
600
600
700 800 o Toutlet, C
a
900
700
800
900
o
T, C
b
Fig. 1. CH4 conversion (a) and CO selectivity (b) vs T in POM on spiral (1), gauze (2) and corundum channel-based (3) catalytic elements. Contact time 8 ms, feed 7%CH4 +3.5%O2
1
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V. Sadykov et al. 16
1200
1
ɇ2+ɋɈ,%
4 8 2
4
Temperature, oC
1100
3
12
1000 900
1 2
800
3 4
700 600 5
500
0 600
700 800 o Temperature, C
900
Fig. 2. Syngas content in converted feed vs T for structural elements based upon gauze (1,2) or corundum channel (3, 4) in CH4 DR (1, 3) or oxy-DR (2, 4). Inlet feed 7%ɋɇ4+7%ɋɈ2 (1,3) or 7%ɋɇ4+7%ɋɈ2 + 1.75% O2 (2,4), contact time 8 ms.
0
10
20 30 Length, mm
40
50
Fig. 3. Temperature profiles for monolithic catalysts on corundum (1-4) or fechraloy (5) substrates. Contact time (s): 1-0.02, 2-0.04, 3-0.06, 4-0.1, 5-0.03. 27 % NG in air, no back thermal shield, T at 52 mm measured in the gas phase after monolith.
DR of CH4 were obtained varying in the range of 50-200 s-1 at temperatures in the range of 650-800 oC [5]. Since at temperatures ~ 600 -800oC the mass transfer coefficient for the triangular channel was estimated to be ~ 600-800 c1 , this suggests that for POM the impact of the mass transfer could be appreciable. 4.2. Steady-state performance of monolithic catalysts and its modeling In the autothermal mode, performance of catalysts on corundum and fechraloy foil substrates is practically identical despite a lower content of the active component for the latter case. At the inlet gas temperature of 400°C and the linear velocity in the range of 0.5-2 m/s, methane conversion and CO + H2 yield are nearly constant being equal to ~85-90% and 50-53 vol.%, respectively. These performance characteristics are comparable to those for much more expensive Rh-containing monolithic catalysts [2,3]. No deactivation of performance with time –on-stream was observed.The temperature profiles along the catalyst length (Fig. 3) are rather similar for both types of monolithic substrates. In the narrow inlet part of the monolith highly exothermal reaction of methane combustion occurs leading to a steep rise of temperature. After reaching the maximum at a position depending upon the space velocity (Fig. 3), the temperature of the catalyst declines due to the heat consumption by endothermic steam and dry reforming reactions. The outlet temperature increases with the space velocity reflecting overall increase of the heat generated within the reactor in the nearly adiabatic mode. Less steep temperature profile (from Tmax to Tend) for the catalyst on the fechraloy substrate implies some impact of the heat transfer by conduction along the metal foil. As
365
Performance of monolithic catalysts with complex active component
revealed by modeling (Fig. 4), for the main part of the monolith the catalyst temperature exceeds that of the gas phase thus demonstrating importance of the heat and mass transfer processes. The peak temperature is correctly reproduced only with a due regard for steam reforming occurring even in the presence of gas-phase oxygen, apparently within pores of corundum substrate (vide supra). This reaction is also favored by a big difference between the concentration of reagents (especially, oxygen) in the gas phase and at the surface of the channel due to the effect of the diffusion-controlled mass transfer (Fig. 5). 4.3. Ignition characteristics and their modeling Under conditions of high-temperature POM process, complex perovskite-like LaNi(Pt)O3 oxide is reduced yielding small highly reactive Nio particles promoted by Pt [4,5]. This decreases typical ignition temperature of POM for mildly reoxidized catalyst to ~ 400 oC from 500-600 oC for asprepared sample. Ignition usually starts at some intermediate point within the monolith (Fig. 6). The ignition point moves downstream with decreasing the contact time (increasing space velocity). After ignition, the hot spot moves towards the monolith inlet. Modeling describes reasonably good experimental temperature profiles within the monolith. The peak of deep oxidation products concentration –H2O and CO2 (Fig. 7) is achieved within 30 s from start-up, when the temperature in the middle of monolith increases up to ~ 750 oC. After attainment of the steady-state temperature profile within all monolith, concentration of deep oxidation products decreases and that of CO increases to nearly constant levels, while a slow increase of H2 content continues. This suggests that CO formation is mainly controlled by the primary process of CH4 transformation within the inlet part, while for H2 formation a slower stage of CH4 SR is important as well. These dynamic features agree with those earlier observed for Rh/ alumina monolith [2]. catalyst
Gas velocity = 1.1 m/s CH4=28.5%
0,30
1000
0,25
900
Mole fractions
O
Temperature, C
1100
800
gas
700 600 500
CH4 (surface)
0,20
CH4 (flow)
0,15
O2(surface)
0,10 0,05
400
O2(flow)
0,00 0
300 0
1
2
3
4
5
6
7
1
2
3
4
5
6
7
Length, cm
Length, cm
Fig. 4. Experimental (points) and calculated (line) temperature profiles within the monolithic catalyst and in the gas phase. 28.5% of NG in air, contact time 0.05 s.
Fig. 5. Calculated profiles of gas-phase and surface concentrations of reagents. Contact time 0.05 s, inlet T 370 oC, 28.5% of NG in air.
366 Concentration, % vol.
V. Sadykov et al. H2
40 35 30 25 20 15 10 5 0
CH4
CO2 0
Fig. 6. Comparison of experimental (points) and calculated (lines) dynamics of temperature variation at selected points (1-2, 2-5, 3-10, 425 mm) in monolithic catalyst on corundum substrate during start-up. Contact time 0.11 s, 25.5% NG +15.7 %Ɉ2 in N2
CO
O2
20
40
60 80 time, s
400 500
Fig. 7. Typical dynamics of the concentration of reagents and products variation during start-up for monolithic catalyst on corundum substrate. Start-up by switching the stream of air through catalyst preheated to 400 oC for feed 27% NG in air.
At the same contact time, the temperature profile stabilizes more rapidly for the catalysts based on metallic substrate as compared to corundum ones due to a higher thermal conductivity of the metal foil. 5. Conclusions Experimental studies and modeling demonstrated importance of the heat and mass transfer for the process of the natural gas partial oxidation into syngas at short contact times on monolithic catalysts with a complex active component Pt/LaNiO3/Ce-Zr-La-O. A simplified approach for modeling based upon using rate constants for the reactions of methane transformation into syngas estimated for separate structural elements of monolithic catalysts in nearly isothermal conditions was successfully verified. This work was carried out in frames of European Associated Laboratory on Catalysis. Support by ISTC 2529 Project is gratefully acknowledged. References 1. 2. 3. 4. 5. 6. 7. 8. 9.
G. Veser, J. Frauhammer, Chem. Eng. Sci. 55 (2000) 2271. R. Schwiedernoch, S. Tischer, C. Correa, O. Deutschmann, Chem. Eng. Sci. 58 (2003) 633. R. Horn, K.A. Williams, N.J. Degenstein, L.D. Schmidt, J. Catal. 242 (2006) 92. V.A. Sadykov, S.N. Pavlova et al. Kinetics Catal. 46 (2005) 227. S. Pavlova, N. Sazonova, V. Sadykov, S. Pokrovskaya, V. Kuzmin, G. Alikina, A. Lukashevich, E. Gubanova, Catal. Today 105 (2005) 367. G. Groppi, E. Tronconi, P. Forzatti, Catal. Rev.-Sci. Eng., 41 (1999) 227. D.L. Trimm, C.-W. Lam, Chem. Eng. Sci. 35 (1980) 1405. J.Wei, E. Iglesia, J. Catal., 224 (2004) 370. T. Numaguchi, K. Kikuchi, Chem. Eng. Sci. 43 (1988) 2295.