Atomic Ru Immobilized on Porous h-BN through Simple Vacuum Filtration for Highly Active and Selective CO₂ Methanation

Abstract

As CO 2 emissions are sharply increasing, processes for converting CO 2 into value-added products are becoming more desirable. Ruthenium-based catalysts are the most active for CO 2 methanation; however, their substantially higher cost relative to transition metals makes them prohibitive for industrial application. In this study, we demonstrate porous hexagonal boron nitride (pBN) supports (an ideal support material for thermocatalysts due to the high thermal stability and conductivity) to improve the utilization of Ru and simultaneously enhance the catalytic activity and selectivity for CO 2 methanation. A simple vacuum filtration process is proposed that allows the Ru precursor to quickly locate the defects of pBN, where atomic Ru can be restricted onto the defects via B, N coordination through an annealing treatment. The B and N coordinations reduce the valence state of atomic Ru. The as-prepared catalyst with low Ru loading (0.58 wt %) exhibits CH 4 selectivity up to 93.5%, catalytic stability after 110 h, and a higher reaction rate [1.86 mmol CO 2 /(g cat s)] at 350 °C and 1.0 MPa compared to other nanoparticle catalysts. Both atomic-scale size and low valence state of atomic Ru supported on pBN are responsible for the improvement of CH 4 production rate as confirmed by density functional theory simulation.

Optimization Strategies for Selective CO2 Electroreduction to Fuels

“…The poor stability of CO 2 RR has several causes, depending on the type of cathode. For example, noble metals suffer from CO poison during the reduction process [12]; metallic chalcogenides are easily reduced at the reduction environment [13]; and agglomeration of catalysts with high dispersion decreases active site concentration [14]. The most problematic one is the low selectivity, which results in costly separation steps and energy consumption at downstream.…”

Review of CO2 Reduction on Supported Metals (Alloys) and Single-Atom Catalysts (SACs) for the Use of Green Hydrogen in Power-to-Gas Concepts

“…In contrast to the findings of Aitbekova et al [59], a recent study by Fan et al, depicted that atomically dispersed Ru into porous hexagonal boron nitride supports shows high selectivity toward methanation of CO 2 with extended time-on-stream stability. These catalysts are surprisingly more active than supported Ru nanoparticles [134]. The stability of these catalysts during reaction was attributed to the coordination of Ru by B and N atoms into defects sites of these 2D materials.…”

Heterogeneous Single Atom Environmental Catalysis: Fundamentals, Applications, and Opportunities

“…An idiosyncratic result was reported for Ru SAs immobilized on a nonoxide support, e.g., porous hexagonal boron nitride, which exhibited a high selectivity (93.5%) toward CH 4 . [170] This abnormal phenomenon was rationalized by the low oxidation state of Ru due to the B, N atoms coordination as revealed by DFT simulation. It is worth mentioning that the product selectivity is also sensitive to the reaction temperature.…”