Methanation of CO₂ over <i>Y</i>b‑Promoted Ni/Al₂O₃ Catalysts Prepared\nby Solution Combustion

Abstract

Introducing\na proper promoter into Ni-based catalysts for CO₂ methanation\nis an effective method to improve their catalytic\nperformance. In this work, we prepare a series of <i>Y</i>b-modified Ni/Al₂O₃ catalysts by a solution\ncombustion approach and characterize them using various techniques,\nincluding nitrogen adsorption, X-ray diffraction (XRD), scanning electron\nmicroscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron\nspectroscopy (XPS), temperature-programmed hydrogen reduction (H₂-TPR), hydrogen desorption (H₂-TPD), carbon dioxide\ndesorption (CO₂-TPD), Fourier transform infrared (FTIR),\nand Thermogravimetric/differential thermal (TG/DTA), and test their\nCO₂ methanation activity in a fixed-bed reactor under conditions\nof 200–500 °C, 0.1–2 MPa, space velocities ranging\nfrom 7200 to 16,200 h^–1, and feed molar ratios of\nH₂/CO₂ from 1 to 4. We found that <i>Y</i>b modification promotes the dispersion of reducible NiO on Al₂O₃ and simultaneously leads to the creation of\nnew <i>Y</i>b-involved CO₂ chemisorption sites\nresponsible for the improved catalytic activity and stability of Ni/Al₂O₃ catalysts for CO₂ methanation so\nthat the <i>Y</i>b-modified Ni/Al₂O₃ catalysts exhibit higher catalytic activities than Ni/Al₂O₃ catalysts without <i>Y</i>b.