Expanded surface amino-functionalization on diverse supports for highly dispersed and efficient Ni-based CO2 methanation catalysts

Abstract

Ni-based catalysts are widely studied for CO₂ methanation due to their cost-effectiveness and abundance. However, they face challenges such as thermal sintering at high temperatures and insufficient activity at low temperatures due to kinetic barriers. To address these issues, this study built on previous work using amino-functionalized KCC-1 support [1] and extended the approach to porous silica-based materials (SBA-15, MCM-41, ZSM-5, SiO₂) and metal oxides (Al₂O₃) with abundant surface hydroxyl groups. These supports were functionalized with amino groups and employed for Ni-based catalysts, demonstrating the universal applicability of this approach across diverse support materials. The amino-functionalized surface promoted the regioselective precipitation of Ni precursors within porous channels, yielding highly dispersed Ni nanoparticles. Comprehensive characterizations (XRD, FT-IR, SEM-EDS, TEM, XPS, H₂-TPR, CO₂-TPD) revealed improved Ni dispersion, redox performance, metal-support interactions, and surface basicity. Additionally, in-situ DRIFTS was used to elucidate the reaction mechanisms of CO₂ methanation over these catalysts. Results showed that amino-functionalization anchored Ni active sites, producing smaller, uniformly dispersed nanoparticles, significantly enhancing CO₂ conversion and CH₄ selectivity, particularly improving low-temperature activity. Notably, the low-temperature activity improved substantially, with the CO₂ conversion increasing from 22.2 % (20Ni/SBA-15) to 55.4 % (20Ni/AF-SBA-15) at 280 °C. This approach demonstrated universal applicability across diverse supports, offering a promising strategy for improving Ni-based catalyst performance in CO₂ methanation and potentially other catalytic reactions.