Stabilized Rh/hydroxyapatite catalyst for furfuryl alcohol hydrogenation: Application of oxidative strong metal-support interactions in reducing conditions

Abstract

The strong metal-support interaction (SMSI) is a widely recognized concept in heterogeneous catalysis, known for significantly enhancing catalyst stability and potentially modulating catalytic performance. However, because the SMSI effect is generally reversible, it tends to diminish under redox conditions opposite to those used for its construction. Consequently, its application is typically limited to conditions that are the same or similar to those under which it was formed. Herein, we report the application of oxidative SMSI (O-SMSI) constructed on hydroxyapatite-supported Rh catalyst (Rh/HAP) in a reductive reaction, the hydrogenation of furfuryl alcohol. In situ diffuse reflectance infrared Fourier transform spectroscopy of CO adsorption and electron microscopy measurements reveal that high-temperature oxidation treatment at 500 ​°C induced the occurrence of O-SMSI on the Rh/HAP catalyst, accompanied by the encapsulation of Rh particles by the support. Upon the O-SMSI, the Rh species were effectively stabilized on the support surface, with significant suppression of sintering and leaching during liquid-phase reactions. As a result, the catalyst showed stable furfuryl alcohol conversion and cyclopentanone selectivity during recycling tests. Furthermore, it was found that the O-SMSI and the associated encapsulation behavior on the Rh/HAP system were only partially reversible rather than completely reversible. Even after high-temperature reduction at up to 600 ​°C, a portion of the SMSI effect remains, ensuring the stability of the catalysts in reductive reactions. This discovery greatly expands the application scope of SMSI catalysts and provides a new way to prepare stable hydrogenation catalysts.