Bimetallic NiSn supported on mesoporous carbon as an efficient catalyst for selective methanol synthesis from CO2

Abstract

Global warming and climate change represent the most significant environmental challenges of the 21st century, primarily attributed to the rise in CO₂ emission in the atmosphere. Efforts to mitigate this increase involve exploring various methods to reduce CO₂ levels, with chemical reactions, such as hydrogenation, being a prominent approach. However, the stable and inert nature of CO₂ necessitates the use of catalysts to facilitate its conversion. In this research, NiSn nanoparticles with varying atomic ratios were deposited onto a mesoporous carbon support and subsequently utilized as catalysts for CO₂ conversion through hydrogenation reactions at ambient pressure. The diffraction patterns of NiSn/MC reveal peaks indicating the presence of a graphitic carbon structure and the existence of a nickel-tin alloy. SEM-EDX mapping and TEM characterization demonstrate the uniform dispersion of NiSn particles on the mesoporous carbon surface, without the formation of agglomerated particles. Catalytic hydrogenation reactions indicate that the atomic ratio of Ni:Sn significantly influences the catalyst activity and selectivity for methanol formation. Among the Ni_xSn_y/MC catalysts and monometallic Ni/MC, Sn/MC, and NiSn NPs without support, Ni₅Sn₁/MC demonstrated the highest CO₂ conversion of 39.9 %. Additionally, at a reaction temperature of 175 °C and a CO₂:H₂ gas ratio of 1:7, Ni₅Sn₁/MC exhibited a methanol yield of 86.31 mmol/g_cat, outperforming other catalysts in the study.