Synthesis of thermally stable metal substituted hydroxy apatites for the selective oxidation of light paraffins

Abstract

ABSTRACT. Hydroxyapatite and a series of hydroxyapatite-type compounds containing Co, Fe or Sr were synthesized by co-precipitation and characterized by ICP-OES, BET, IR, Raman spectroscopy, powder and in-situ XRD, SEM, TEM, TPR, TPD and TGA. In-situ XRD and TGA studies indicate that the materials are able to maintain their structure at temperatures reaching 900 °C. The TPD data indicated that acidic sites of varying strengths were present in all the three hydroxyapatites. From SEM, the surface of the materials consisted of an agglomeration of irregular plate-like particles. The catalytic activity of the compounds was investigated in the oxidation of n-pentane and n-hexane. The conversion of the feed and composition of the products were largely influenced by changes in the temperature and flow rates. For n-pentane, the products consisted of lower hydrocarbons and oxygenated compounds, carbon oxides and very small amounts 1,3-pentadiene, furan and furfural. Low conversions of n-hexane were obtained for all the tested catalysts and selective products were the hexene isomers and some aromatics.

One pot peroxidation of oleic acid rich Azadirachta indica oil over bio‐waste derived heterogeneous catalyst

“…The additional mass loss was due to the removal of all the organic compounds present in the core of the sample. A similar profile was observed in Singh and Jonnalagadda's work . However, the hydroxyapatite prepared was synthetic (i.e.…”

Decorated multi-walled carbon nanotubes with Sm doped fluorapatites: synthesis, characterization and catalytic activity

“…Rare earth elements have the characteristics of unoccupied 4f orbitals and lanthanide contraction, which result in their applicability as catalysts or catalytic components. [44][45][46] We also reported the advantages of using rare earth-loaded mixed oxide catalysts in value-added conversions. 34 38,39 Triazole-containing organics possess anti-microbial, antimalarial, anti-tumor, anti-tubercular, anti-inammatory, and anti-convulsant properties.…”

Nanostructured Samarium Doped Fluorapatites and Their Catalytic Activity towards Synthesis of 1,2,4-Triazoles

“…The above applications highlight the importance of a facile synthetic route for triazoles to surmount the hindrances such as elaborate reaction conditions, high temperature maintenance, long work-up procedures and low yields. In the earlier studies, we have reported the synthesis and characterization of diverse metal (Fe Co, Pt, Sr, Ir, and V) substituted hydroxyapatites and their scope as heterogeneous catalysts in value-added organic transformations such as selective oxidation of n-pentanes and in Knoevenagel condensation reactions with excellent yields [47,48,49,50]. We have also reported the scope of Sm(III) based coordination polymer as a viable yellow light emitter [51].…”