Syngas Production via Steam–CO₂ Dual Reforming of Methane over LA-Ni/ZrO₂ Catalyst Prepared by <scp>l</scp>-Arginine Ligand-Assisted Strategy: Enhanced Activity and Stability

Abstract

A highly dispersed supported nickel catalyst (LA-Ni/ZrO 2 ), synthesized by a facile l -arginine ligand-assisted incipient wetness impregnation (LA-IWI) approach, demonstrates much superior catalytic activity and exceptional stability for steam–CO 2 dual reforming of methane in comparison with the classical Ni/ZrO 2 catalyst by the IWI method. The origin of the enhanced activity and stability of the developed LA-Ni/ZrO 2 catalyst as well as the role of the Ni–{( l -Arg)} complex as the Ni precursor is revealed by employing diverse characterization techniques including X-ray diffraction (XRD), N 2 adsorption (BET), transmission electron microscopy (TEM), H 2 temperature-programmed reduction (H 2 -TPR), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (Raman), CO chemisorption, temperature-programmed hydrogenation (TPH), and thermogravimetric analysis (TGA). The superior catalytic activity of the developed LA-Ni/ZrO 2 catalyst to the classical Ni/ZrO 2 can be ascribed to the higher Ni dispersion, intensified Ni–support interaction, the enlarged oxygen vacancies, as well as the increased t -ZrO 2 content and enhanced reducibility of NiO led by oxygen vacancies. More interestingly, although a larger amount of coke depositing on the spent LA-Ni/ZrO 2 catalyst in comparison with that on the spent Ni/ZrO 2 can be observed by TGA and TPH measurement, the developed LA-Ni/ZrO 2 illustrates much higher catalytic stability to Ni/ZrO 2, ascribed to the superior thermal sintering resistance of Ni nanoparticles and the different coke morphologies confirmed by TEM images led by intensified interaction of Ni and the ZrO 2 support. The much superior catalytic activity and stability of the developed LA-Ni/ZrO 2 catalyst endows it to be a promising candidate for syngas production with diverse H 2 /CO ratios via steam–CO 2 dual reforming of methane.