1 Introduction
2 Experimental
2.1 Catalyst Preparation
Catalyst | Metal oxide content (wt%) | k∞ (m s−1) | Ea (kJ mol−1) | η | |||||
---|---|---|---|---|---|---|---|---|---|
Co3O4
| PdO | CeO2
| CH4
| CO | CH4
| CO | CH4
| CO | |
Pd0.001 | – | 8 | – | 20.6 | 10.4 | 24.4 | 25.7 | 0.94 | 0.34 |
Co0.1 | 29 | – | – | Inactive | |||||
Co1 | 59 | – | – | 3.12 | 2.24 | 36.9 | 17.2 | 0.88 | 0.12 |
Co1Pd0.001 | 14 | 1 | – | 1.73 | 1.68 | 39.8 | 20.1 | 1.0 | 0.73 |
Co1Ce1 | 8 | – | 0.01 | 1.01 | 1.93 | 28.16 | 20.3 | 0.91 | 0.060 |
2.2 Kinetic Tests
3 Reactor Modelling
3.1 Material Balance Equations
3.2 Energy Balance Equations
3.3 Reaction Kinetics
3.4 Modelling Conditions
Reactor internals | Dh (mm) | a (m−1) | Mesh/cpsi | Re | Heat and mass transfer equation | Ref. |
---|---|---|---|---|---|---|
Wire gauze | 0.33 | 8,186 | 61.7 | 12 |
\( Nu = \frac{{2[(4/\pi ) \cdot L^{*} ]^{ - 1/2} }}{{[1 + ({\it{Pr}} /0.0207)^{2/3} ]^{1/4} }}\left( {0.270 \cdot \left( {{ {\it{Pr}} } \cdot L^{*} } \right)^{ - 0.213} } \right) \)
\( Sh = \frac{{2[(4/\pi )L^{*M} ]^{ - 1/2} }}{{[1 + (Sc/0.0207)^{2/3} ]^{1/4} }}\left( {0.270 \cdot \left( {Sc \cdot L^{*M} } \right)^{ - 0.213} } \right) \)
| |
Monolith | 2.15 | 1,339 | 100 | 80 |
\( Nu = 3.608\left( {1 + \frac{0.095}{{L^{*} }}} \right)^{0.45} \)
\( Sh = 3.608\left( {1 + \frac{0.095}{{L^{*M} }}} \right)^{0.45} \)
|
3.5 Reactor Performance
-
For the reaction: CH4 + 2O2 → CO2 + 2H2O the heat of reaction at the catalyst surface was calculated to be, ∆H°R = −803 kJ mol−1,
-
For the reaction: CO + 0.5O2 → CO2 the heat of reaction at the catalyst surface was calculated to be, ∆H°R = −283 kJ mol−1,
-
Properties along the channel varied as a function of the local temperature,
-
The inlet gas temperature was assumed to 673 K,
-
The gas superficial velocity was assumed to 1 m s−1; the corresponding Reynolds numbers are given in Table 2.
Catalyst | Methane combustion | CO combustion | ||
---|---|---|---|---|
Wire gauze | Monolith | Wire gauze | Monolith | |
Pd0.001 | 300,000 | 51,429 | 60,000 | 7,826 |
Co1 | 6,000 | 938 | 16,363 | 2,609 |
Co1Pd0.001 | 2,368 | 375 | 51,429 | 7,059 |
Co1Ce1 | 9,000 | 1,286 | 4,286 | 652 |