Hydroxyapatite‐Based Catalysts: Influence of the Molar Ratio of Ca to P

Ma, Zhen

doi:10.1002/9783527830190.ch4

Cited by 1 publication

(1 citation statement)

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“…As the main mineral component of bones and teeth, it can be obtained from natural sources, or it can be synthesized in mild conditions from cheap precursors. − Besides playing an important role in many clinical applications such as drug design and bone tissue regeneration, it has proved to be efficient as a support and (co)active phase in heterogeneous catalysis. ,,− It has important advantages over other materials used in the latter field. Its specific surface area is higher than that of perovskites, , while its thermal and chemical stabilities are generally better than those of zeolites and metal–organic frameworks. ,, Its intrinsic surface acid–base properties can easily be tuned by varying its Ca/P ratio, − and its framework Ca 2+ cations can be substituted by catalytically active metals (Cu 2+ , Ni 2+ , Ag + , etc. ). ,, This leads to multifunctional catalysts suitable for a wide range of applications. ,, Through surface cation deposition in the excess of solution or strong electrostatic adsorption (SEA), at substituent metal contents of 1–2 wt %, it is possible to obtain HAp catalysts with atomically dispersed active sites showing a particularly high catalytic performance and an exceptional resistance to sintering under harsh reaction conditions. − …”

Section: Introductionmentioning

confidence: 99%

Hydroxyapatite: A Matrix for Metal Exsolution Leading to Highly Dispersed Catalytically Active Species

Schnee,

Ben Romdhane,

Devred

et al. 2024

Chem. Mater.

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Hydroxyapatite (Ca10(PO4)6(OH)2 or HAp)the main mineral component of bones and teethis a material of great interest not only in biomedical applications but also in heterogeneous catalysis. Its framework Ca2+ cations can be substituted by a wide variety of catalytically active metals (Cu2+, Ni2+, Ag+, etc.). In the present work, for the first time, to our knowledge, we demonstrate that highly valuable HAp-based catalysts can be obtained through a novel advantageous bottom-up approach. Unlike classical surface cation deposition in the excess of solution, this approach is one-pot. It consists in preparing the bulk-metal-substituted HAp by coprecipitation and then submitting it to a finely adjusted thermal treatment under a H2-containing gas flow. For a Cu(∼1.5 wt %)-HAp, we show that such a treatment at 450 °C leads to the exsolution of the whole Cu contained in the material, leading to highly dispersed Cu species at the HAp surface. After appropriate activation, these Cu species are active in the selective catalytic reduction of NO x by NH3. The phenomenon of exsolution has been reported so far mainly for perovskites but to lead to metal nanoparticles and not to highly dispersed species as achieved here.

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