Hydrogen Doping into MoO₃ Supports toward Modulated Metal–Support Interactions and Efficient Furfural Hydrogenation on Iridium Nanocatalysts

Abstract

As promising supports, reducible metal oxides afford strong metal-support interactions to achieve efficient catalysis, which relies on their band states and surface stoichiometry. In this study, in situ and controlled hydrogen doping (H doping) by means of H spillover was employed to engineer the metal-support interactions in hydrogenated MoO -supported Ir (Ir/H-MoO ) catalysts and thus promote furfural hydrogenation to furfuryl alcohol. By easily varying the reduction temperature, the resulting H doping in a controlled manner tailors low-valence Mo species (Mo and Mo ) on H-MoO supports, thereby promoting charge redistribution on Ir and H-MoO interfaces. This further leads to clear differences in H chemisorption on Ir, which illustrates its potential for catalytic hydrogenation. As expected, the optimal Ir/H-MoO with controlled H doping afforded high activity (turnover frequency: 4.62 min ) and selectivity (>99 %) in furfural hydrogenation under mild conditions (T=30 °C, PH2 =2 MPa), which means it performs among the best of current catalysts.

Furfural Adsorption and Hydrogenation at the Oxide‐Metal Interface: Evidence of the Support Influence on the Selectivity of Iridium‐Based Catalysts

“…Such effects have also been investigated in part in the reductive conversion of furfural, where both monometallic and alloyed Ir-based catalysts have been successfully employed. [12,14,30,49,50] Yu et al have evidenced the remarkable activity of the interface sites of Irmetal oxide heterostructures, and specifically of Ir/CoO x , in the reduction of furfural. [49] The beneficial effects deriving from the modulation of metal-support interactions by hydrogen doping into the MoO 3 support for Ir-based catalysts for furfural hydrogenation have been recently highlighted by Xie et al.…”

“…[49] The beneficial effects deriving from the modulation of metal-support interactions by hydrogen doping into the MoO 3 support for Ir-based catalysts for furfural hydrogenation have been recently highlighted by Xie et al. [30] Herein, preformed, colloidal iridium nanoparticles, synthesized using tetrakis(hydroxymethyl)phosphonium chloride (THPC) as both reducing and protecting agent, were immobilized onto three different metal oxides, namely CeO 2 , TiO 2 and NiO. The catalytic performance of the Ir-based catalysts was evaluated in both direct and catalytic transfer hydrogenation of furfural in water.…”

“…In addition, the support, is known to play a fundamental role, for example, strong metal‐support interactions (SMSI) can contribute to modulation of the catalytic performances through electronic interactions [28] . Moreover, in some cases, cooperative catalysis between metal nanoparticles and the support surface has been reported for furfural hydrogenation [28–33] . In this regard, we have recently demonstrated that furfural hydrogenation proceeds with enhanced selectivity to tetrahydrofurfuryl alcohol via a dual‐site mediated mechanism over a Pd/NiO catalyst: the Pd centre is responsible for the dissociation of hydrogen, which subsequently spills over onto the NiO support, where furfural is adsorbed and activated [34] …”

“…In particular, electron donor supports, such as ceria and phosphorylated titania, stabilize Ir in the metallic form, which is usually the active species in hydrogenation reactions. Such effects have also been investigated in part in the reductive conversion of furfural, where both monometallic and alloyed Ir‐based catalysts have been successfully employed [12,14,30,49,50] . Yu et al .…”

H-Spill storage to maximize the catalytic performances of Pd-based bimetals@Ti3C2Tx MXenes in selective semihydrogenations

“…Associated with H 2 dissociation, spillover supports could be chosen from various substrates, including other metals, [25][26][27] oxides, [28][29][30] carbon-based materials 31,32 and metal organic frameworks. [33][34][35] Besides, MXenes are a new family of 2D nanosheets from transition metal carbides/ nitrides, and the great surface area and facile surface modification make MXenes potential ideal supports for heterogeneous catalysis.…”