Introduction
Experimental
Catalyst preparation
Catalyst characterization
Catalytic activity tests and kinetic studies
Results and discussion
Effect of the support
Effect of the NiO loading
Tab.1 CH4 reaction rate over NiO/CeO2 catalysts at 360°C |
Samples | Cat./mg | Flow rate/(mL·min‒1) | Concentration of CH4 /vol-% | Conversion of CH4 /% | CH4 reaction rate /(×10‒4 mmol·g‒1·s‒1) |
---|---|---|---|---|---|
1 wt-% NiO/CeO2 | 200 | 50 | 1 | 6.4 | 1.09 |
3 wt-% NiO/CeO2 | 200 | 50 | 1 | 10.4 | 1.77 |
5 wt-% NiO/CeO2 | 200 | 50 | 1 | 14.6 | 2.49 |
7 wt-% NiO/CeO2 | 200 | 100 | 1 | 9.0 | 3.07 |
10 wt-% NiO/CeO2 | 200 | 100 | 1 | 10.7 | 3.63 |
15 wt-% NiO/CeO2 | 200 | 100 | 1 | 10.3 | 3.51 |
20 wt-% NiO/CeO2 | 200 | 100 | 1 | 10.9 | 3.70 |
Effect of water vapor in the feed gas
Determination of the kinetic parameters of CH4 oxidation
Catalyst characterization
XRD
N2 adsorption/desorption
Tab.2 Textural properties and catalytic activities of CeO2 and NiO/CeO2 samples for CH4 combustion |
Samples | Crystallite size /(na·ma) | Surface area /(m2·g‒1) | Pore volume /(cm3·g‒1) | Catalytic activity /°C | ||
---|---|---|---|---|---|---|
T10 | T50 | T90 | ||||
CeO2 | 8 | 76.4 | 0.206 | 456 | 540 | 615 |
1 wt-% NiO/CeO2 | 8.1 | 70.4 | 0.197 | 381 | 471 | 575 |
3 wt-% NiO/CeO2 | 8.3 | 68.8 | 0.195 | 362 | 442 | 516 |
5 wt-% NiO/CeO2 | 8.5 | 65.3 | 0.185 | 352 | 430 | 493 |
7 wt-% NiO/CeO2 | 8.8 | 61.1 | 0.183 | 349 | 424 | 487 |
10 wt-% NiO/CeO2 | 8.9 | 58.1 | 0.173 | 333 | 415 | 467 |
15 wt-% NiO/CeO2 | 8.9 | 57.2 | 0.171 | 350 | 416 | 472 |
20 wt-% NiO/CeO2 | 9 | 55.5 | 0.169 | 355 | 410 | 467 |
10 wt-% NiO/CeO2 (used)b | 10.6 | 45.5 | 0.154 | – | – | – |
a) Crystallite sizes were calculated from the line broadenings of the (111) plane of CeO2 using the Scherrer equation; b) 10% NiO/CeO2 catalyst collected after reaction at 600°C for 150 h. |