Plasma-enhanced catalytic CO₂ hydrogenation: Experimental investigation of Ni-based catalysts performance and techno-economic feasibility compared to conventional thermal systems

This study investigates the performance enhancement of CO₂ hydrogenation through plasma-assisted catalysis compared to conventional thermal processes, addressing critical efficiency gaps in carbon utilization technologies. We synthesized and characterized a series of Ni-based catalysts supported on different metal oxides (Al₂O₃, CeO₂, ZrO₂) and systematically evaluated their performance under both thermal-only and plasma-coupled reaction conditions at varying temperatures (200–450°C), pressures (1–10 bar), and H₂/CO₂ ratios (2:1–4:1). Our experimental results demonstrate that dielectric barrier discharge (DBD) plasma integration achieves 34.7% higher CO₂ conversion rates at 300°C compared to thermal catalysis at 400°C, while maintaining 89.3% selectivity toward CH₄. The Ni/CeO₂ catalyst exhibited superior performance with a CO₂ conversion of 78.6% and turnover frequency of 2.4 × 10⁻² s⁻¹ under plasma-assisted conditions (300°C, 5 bar, H₂/CO₂ = 3:1), representing a 2.1-fold improvement over conventional thermal operation at equivalent temperature. Characterization through XRD, TEM, XPS, and H₂-TPR revealed that plasma discharge enhances metal-support interaction, increases oxygen vacancy concentration by 43%, and reduces Ni particle size from 12.3 nm to 8.7 nm, thereby improving catalyst dispersion and active site accessibility. Kinetic analysis revealed that plasma activation reduces the apparent activation energy from 89.4 kJ/mol to 62.1 kJ/mol, indicating enhanced CO₂ dissociation through electron-impact excitation and vibrational excitation mechanisms. Long-term stability tests over 200 h showed minimal deactivation (< 7% conversion loss) under plasma-coupled conditions, attributed to reduced carbon deposition and enhanced catalyst regeneration through reactive oxygen species generation. Techno-economic assessment based on a conceptual 10,000 ton/year CH₄ production facility indicates that plasma-assisted catalysis reduces capital expenditure by 18–23% through lower operating temperatures and simplified reactor design, despite 15% higher electricity consumption. Life cycle analysis demonstrates a 28% reduction in overall energy intensity (MJ/kg product) and 34% lower greenhouse gas emissions compared to conventional high-temperature thermal processes when coupled with renewable electricity sources. Our findings establish plasma-enhanced catalysis as a viable pathway for efficient CO₂ utilization, offering simultaneous improvements in conversion efficiency, energy economy, and environmental sustainability. The study provides quantitative performance benchmarks and identifies optimal operating windows that can inform scale-up strategies and support China's carbon neutrality targets through practical implementation of CO₂ conversion technologies.