Benchmarking potential catalysts and choice of descriptor for CO2 methanation using transition metal based catalysts

Abstract

Supported Pt, Pd, Rh, Ru as Noble and Ni, bimetallic Ni-M (M = Co, Cu, Fe, with Ni/M = 3:1 by weight) as Non-noble catalysts were synthesized, characterized, and tested for CO₂ methanation to benchmark and obtain a suitable descriptor. Noble metal catalysts are reduced almost completely with a lower onset of reduction temperature than Non-noble catalysts. The reduced Ni-M catalysts possessed an alloy phase in each as substantiated by a peak shift (∼ 0.2–0.4º) with reference to metallic nickel. The catalysts are benchmarked for their activity at 523 K by reporting turnover frequency (${\mathrm{TOF}}_{{\mathrm{CO}}_2}$). The Ni-Fe and Rh catalysts possess maximum ${\mathrm{TOF}}_{{\mathrm{CO}}_2}$ (∼ 35 × 10⁻³ sec⁻¹), while Ru, Rh catalysts have better CH₄ selectivity (∼99 %) than Ni-Fe (95 %) catalyst. The knowledge of descriptor is revisited for this reaction by calculating surface properties and observed that there exists a volcano relationship between dissociative CO₂ adsorption energy (E_diss) and ${\mathrm{TOF}}_{{\mathrm{CO}}_2}$.