Modulation of extra-framework oxygen species in C12A7 catalyst for oxidation reactions
(2023)
Files
ThesisIsaacMezaTrujillo-Readytoprint.pdf
Open Access - Adobe PDF
- 4.57 MB
Details
- Authors
- Supervisors
- Gaigneaux , Eric
- Abstract
- The nature of surface oxygen species in a catalyst, whether nucleophilic or electrophilic, can significantly influence reactivity patterns and play a crucial role in determining reaction pathways and products in oxidation reactions. This thesis aims to evaluate controlling the activity and selectivity of mayenite (C12A7:12CaO·7Al₂O₃) in oxidation reactions by modulating its extra-framework oxygen species distribution. A preparation method employing the solution combustion approach was developed to enhance C12A7 textural properties. The improved texture led to higher activity and CO₂ selectivity in the total oxidation of carbon black (CB). Then, the influence of adjusting the distribution of extra-framework oxygen species in C12A7 on its catalytic performance was investigated in propane oxidation. By manipulating various parameters during the preparation or post-activation of C12A7, entrapped hydroxyl anions within its structure were significantly reduced, promoting the dominance of desired oxygen species. Despite employing C12A7 catalysts with varying distributions of electrophilic or nucleophilic extra-framework oxygen species, effective manipulation of product distribution (selectivity) was not achieved. This limitation was attributed to the dynamic re-equilibration of the extra-framework population distribution with the oxidation medium under reaction conditions. Lastly, a cationic doping strategy incorporating copper into C12A7 was explored to enhance its catalytic performance in CB oxidation. Cu-doped C12A7 catalysts evidenced the importance of balancing Cu(II) species dispersion, textural properties, and reactive oxygen species concentration for optimal performance.
- Affiliations
Citations
Meza Trujillo, I. (2023). Modulation of extra-framework oxygen species in C12A7 catalyst for oxidation reactions. https://hdl.handle.net/2078.5/102760