Mechanistic Study and Active Sites Investigation of Hydrogen Production from Methane and H<sub>2</sub>O Steady-State and Transient Reactivity with Ir/GDC Catalyst
Catalytic activity, mechanisms, and active sites were determined for methane steam reforming (MSR) over gadolinium-doped ceria (GDC) supported iridium (0.1 wt%) prepared by impregnation of GDC with iridium acetylacetonate. Isothermal steady-state rate measurements followed by micro-gas chromatograph...
Saved in:
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-11-01
|
| Series: | Hydrogen |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2673-4141/5/4/46 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Catalytic activity, mechanisms, and active sites were determined for methane steam reforming (MSR) over gadolinium-doped ceria (GDC) supported iridium (0.1 wt%) prepared by impregnation of GDC with iridium acetylacetonate. Isothermal steady-state rate measurements followed by micro-gas chromatography analysis were performed at 660 and 760 °C over Ir/GDC samples pretreated in N<sub>2</sub> or H<sub>2</sub> at 900 °C. Transient responses to CH<sub>4</sub> or H<sub>2</sub>O step changes in isothermal conditions were carried out at 750 °C over Ir/GDC pretreated in He or H<sub>2</sub> using online quadrupole mass spectrometry. In the proposed mechanism, Ir/GDC proceeds through a dual-type active site associating, as follows: (i) Ir metallic particles surface as active sites for the cracking of CH<sub>4</sub> into reactive C species, and (ii) reducible (Ce<sup>4+</sup>) sites at GDC surface responsible for a redox mechanism involving Ce<sup>4+</sup>/Ce<sup>3+</sup> sites, being reduced by reaction with reactive C into CO (or CO<sub>2</sub>) depending on the oxidation state of GDC and re-oxidized by H<sub>2</sub>O. Full reduction of reducible oxygen species is possible with CH<sub>4</sub> after He treatment, whereas only 80% is reached in CH<sub>4</sub> after H<sub>2</sub> treatment. |
|---|---|
| ISSN: | 2673-4141 |