Carbon‐Supported Bimetallic Ruthenium‐Iridium Catalysts for Selective and Stable Hydrodebromination of Dibromomethane

Abstract

Catalysts based on individual precious metals on carbon‐ and oxide‐based carriers have shown remarkably selective behavior in the hydrodebromination of CH2Br2 to CH3Br, an important transformation within halogen‐mediated methane upgrading processes. However, the high susceptibility of the active phase to coking and to sintering, which cannot be overcome by controlling the nuclearity of the metal species, hinders their practical implementation. Herein, a platform of carbon‐supported Ir−Ru catalysts with distinct metal ratios at comparable metal nanoparticle size (ca. 1.0 nm) was adopted to systematically study the effects of a second metal on reactivity and stability. Catalytic tests reveal ruthenium‐doped iridium nanoparticles as the first system that combines high CH3Br selectivity (up to 93 %) with unprecedented stability, outperforming any of the previously reported catalysts. This superior performance was rationalized by the intimate interaction between the two metals, forming ruthenium‐poor surface alloys, which enable suppressing deactivation mechanisms as well as over hydrogenation/coking pathways.

Selectivity Control in Palladium-Catalyzed CH2Br2 Hydrodebromination on Carbon-Based Materials by Nuclearity and Support Engineering

“…Active site nanostructuring can be a powerful tool to tune the catalytic performance in both selective hydrogenation and halogen-based applications. − In an effort to combine the high selectivity of Ru NPs with the stability exhibited by Ir ones, alloying Ir NPs with highly dilute amounts of Ru (Ru 0.05 Ir 0.95 ) resulted in high CH 3 Br selectivity (93%) with stable catalytic behavior over 10 h on stream . These results demonstrate the considerable potential of catalyst design strategies at the nanoscale for this reaction.…”

“…17−22 In an effort to combine the high selectivity of Ru NPs with the stability exhibited by Ir ones, alloying Ir NPs with highly dilute amounts of Ru (Ru 0.05 Ir 0.95 ) resulted in high CH 3 Br selectivity (93%) with stable catalytic behavior over 10 h on stream. 23 These results demonstrate the considerable potential of catalyst design strategies at the nanoscale for this reaction. Single-atom catalysts (SACs) offer the possibility to finely tune the metal reactivity via modification of the coordination environment in the host, while simultaneously optimizing metal atom efficiency.…”

Synthesis of Different Nano‐layer Shells (Mono‐, Bi‐, and Alloy Layers)‐Coated Gold Spherical Nanoparticles Core for Catalysis

“…The colloidal preparation of bimetallic nanoparticles (BMNPs) with various nanostructures including alloy, dendrite, crownjewel and core-shell has received significant attention in recent years due to their unique optical and catalytic properties. [1][2][3][4][5] The combination of individual metals in the BMNPs shows unique surface features and physiochemical properties which are different from their corresponding monometallic NPs. [6,7] Among the above-mentioned nanostructures, bimetallic gold (Au) and silver (Ag) core-shell nanostructures attracted significant interest due to their unique surface plasmon resonance (SPR) properties and their applications in catalysis and sensor.…”

“…The colloidal preparation of bimetallic nanoparticles (BMNPs) with various nanostructures including alloy, dendrite, crown‐jewel and core‐shell has received significant attention in recent years due to their unique optical and catalytic properties [1–5] . The combination of individual metals in the BMNPs shows unique surface features and physiochemical properties which are different from their corresponding monometallic NPs [6,7] .…”

N-Heterocyclic Carbene-Based Iridium and Ruthenium/Iridium Nanoparticles for the Hydrogen Isotope Exchange Reaction through C–H Bond Activations

“…It allowed us to improve the selectivity with respect to pure Ru NPs while maintaining good catalytic activities. 37 Although Ru/Ir bimetallic catalysts have been reported for the hydrodehalogenation reaction, 38 hydrogenation of 5-hydroxymethylfurfural 39 and levulinic acid, 40 reduction of NO x by CO, 41 and evolution of oxygen in acidic environments, 42 there have been no reports on HIE. Thus, the use of bimetallic Ru/Ir NPs in this process might then be of interest in overcoming the reduction issue.…”