An STM study of phosphoric acid inhibition of the oxidation of HOPG and carbon catalyzed by alkali salts
Source abstract
Abstract
The role of phosphoric acid as an inhibitor in the oxidation of HOPG and as a neutralizer of alkali salt catalysts is examined using scanning tunneling microscopy, supported by thermogravimetric analysis of carbon powder samples. HOPG samples were oxidized in air primarily at 700 °C, with a few samples oxidized at 800 °C. Reaction time was 20 min. Powder samples were oxidized for 5 min at temperatures ranging from 500 °C to 900 °C and rates of oxidation were determined. STM images of impurity deposits and oxidized samples are presented and analyzed. Two alkali salts are examined, sodium hydroxide and potassium acetate, and both catalyze oxidation at 700 °C. Phosphoric acid proves to be an inhibitor at 700 °C but begins to lose its inhibiting effect at 800 °C. It also demonstrates neutralization of potassium acetate at 700 °C but results for NaOH/phosphoric acid mixtures are less conclusive.
Source: openaire · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: Catalytic Processes in Materials Science · Catalysis and Oxidation Reactions · Mesoporous Materials and Catalysis
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (21)
Show source-provided references
1. Scanning tunneling microscopy and spectroscopy of the thermally oxidized (0001) basal plane of highly oriented pyrolitic graphite10.1016/S0169-4332(97)00500-X ↗
2. Kinetics of carbon—NO reaction studied by scanning tunneling microscopy on the basal plane of graphite10.1006/jcat.1998.2268 ↗
3. Kinetics of graphite oxidation: monolayer and multilayer etch pits in HOPG studied by STM10.1021/jp982025e ↗
4. The mode of attack of oxygen atoms on the basal plane of graphite10.1063/1.445198 ↗
5. Mechanism of carbon gasification—conformation of etch pits on graphite surface with and without tungsten catalyst10.1002/aic.690290223 ↗
6. Kinetics and mechanism of oxidation of basal plane on graphite10.1063/1.442614 ↗
7. Gasification of graphite studied by scanning tunneling microscopy10.1016/0008-6223(91)90044-J ↗
8. Towards a unified theory of reactions of carbon with oxygen-containing molecules10.1016/0008-6223(95)00070-T ↗
9. An electron microscopy study of the low temperature catalyzed steam gasification of graphite10.1016/0021-9517(83)90245-2 ↗
10. Oxidation of carbons and graphites by atomic oxygen: an electron microscope study of surface changes10.1039/tf9656100285 ↗
11. Guzman JE. Kinetics of carbon/carbon composite oxidation and inhibition by site blockage. Masters Thesis, University of Notre Dame, Notre Dame, IN, USA, 2004.
12. Effect of adsorbed phosphorus oxychloride on the oxidation by phosphorus10.1016/0008-6223(72)90069-3 ↗
13. Oxidation protection of carbon materials by acid phosphate impregnation10.1016/S0008-6223(01)00297-4 ↗
14. Van Wazer · 1958 · vol. 1
15. Catalysis of carbon–gas reactions10.1023/A:1012205714699 ↗
16. Étude cinétique de l’Oxydation du graphite inhibée par les phosphates
17. Oxidation behavior and protection of carbon–carbon composites10.1016/0008-6223(87)90197-7 ↗
18. Oxidation protection of carbon materials
19. The inhibition of graphite oxidation by phosphorus additives10.1016/0008-6223(84)90172-6 ↗
20. Oxidation inhibition of carbon fiber preforms and C/C composites by H3PO410.1016/S0955-2219(98)00135-6 ↗
21. The effect of acid treatments on subsequent reactivity of carbon–carbon composites10.1016/0008-6223(89)90064-X ↗