Development of novel nano-hydroxyapatite doped with silver as effective catalysts for carbon monoxide oxidation

Héctor Martínez-Hernández, J. Arturo Mendoza-Nieto, Heriberto Pfeiffer, José Ortiz-Landeros, Lucia Téllez-Jurado

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

A series of novel silver-containing catalysts were synthesized, characterized by X-ray diffraction, infrared spectroscopy, scanning and transmission electron microscopy, N2 adsorption-desorption isotherms, thermogravimetric analysis and then tested for the oxidation of carbon monoxide (CO). The microwave-hydrothermal method was a useful synthesis pathway to structurally incorporate low amounts of silver (2.5–5.0 atomic percentage) to hydroxyapatite (HA) lattice, preserving the crystalline structure of the HA. Specific surface area and particle size (diameter) of the obtained materials were about 52–55 m2/g and 19–47 nm, respectively. Silver-catalysts showed higher catalytic activities than the unmodified HA sample at temperatures between 600 and 850 °C. The best catalytic results were achieved at around 700–800 °C with silver-containing HA samples. However, due to the significant decrease in the crystallinity of the materials exposed to 800 °C; then, 700 °C was established as the best thermal condition for producing CO2 and preserving the HA crystalline structure. Furthermore, cyclic tests demonstrated that silver-containing HA catalysts perform CO oxidation for 3 h through several consecutive catalytic tests at 700 °C without losing neither their activity nor their structural properties, evidencing their high thermal stability under the CO-O2 atmosphere. Thus, the highest reaction rate values (rCO2) were obtained with HA containing 2.5% of silver at 700 °C during the five cycles performed, positioning it as a promissory catalyst with high activity during the CO oxidation at high temperatures. The proposed reaction mechanism was established using these silver-doped materials. This work constitutes the first assessment to add low amounts of silver to increase the activity of this kind of catalytic materials for the CO oxidation reaction.

Original languageEnglish
Article number125992
JournalChemical Engineering Journal
Volume401
DOIs
StatePublished - 1 Dec 2020
Externally publishedYes

Keywords

  • CO oxidation
  • Hydrothermal
  • Hydroxyapatite nanostructures
  • Nanocatalysts
  • Silver-doped catalysts

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