Synergistic Promotion of Nickel/Alumina Catalysts by Samarium: Structural, Surface, and Kinetic Investigations

<jats:p>Rare-earth elements have emerged as effective catalyst promoters owing to their ability to modify surface properties, enhance metal dispersion, and improve thermal stability. In the present study, samarium-promoted nickel alumina catalysts were synthesized and systematically investigated to elucidate the effects of samarium incorporation on structural, surface, and thermal characteristics. The catalysts were prepared by co-doping nickel and samarium species onto alumina supports, followed by comprehensive physicochemical characterization and kinetic analysis. The morphology and elemental distribution of the synthesized catalysts were examined using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and elemental mapping. The results confirmed the successful incorporation and uniform dispersion of samarium and nickel species on the alumina surface. Fourier transform infrared spectroscopy (FTIR) revealed the presence of characteristic metal-oxygen interactions, while X-ray photoelectron spectroscopy (XPS) provided evidence of changes in the surface chemical environment resulting from samarium addition. These observations indicate that samarium acts as an effective promoter, influencing the surface chemistry and interfacial interactions of the catalyst system. Thermogravimetric and differential thermal analyses were employed to investigate the decomposition behaviour and thermal stability of the co-doped materials. The catalysts exhibited gradual mass loss with increasing temperature, accompanied by distinct thermal events associated with precursor decomposition and phase transformation. Kinetic parameters were determined from experimental data, and an increase in the reaction rate constant was observed with rising temperature, indicating enhanced thermal activation of the catalyst system. The calculated kinetic behaviour demonstrated favourable decomposition characteristics and improved thermal stability upon samarium incorporation. Overall, the study demonstrates that samarium significantly modifies the structural and surface properties of nickel-alumina catalysts while improving their thermal performance. The</jats:p>