Low-temperature methanation of syngas in slurry phase over Zr-doped Ni/γ-Al2O3 catalysts prepared using different methods

• Two types of catalysts were prepared by impregnation (IP) and impregnation coprecipitation (ICP) methods.
• ICP catalyst showed better performance of methanation than that of IP catalyst in slurry reactor.
• ICP method is favor for the formation of small size Ni particles and more reducible NiO.
• Zr doping can moderate the interaction between Ni and γ-Al2O3 support and promote the dispersion of Ni.

Syngas methanation was performed at 280–330 °C in a stirred-slurry reactor with Zr-doped Ni/γ-Al2O3 catalysts. The catalysts were prepared using impregnation (IP) and impregnation–coprecipitation (ICP) methods. The catalyst 25Ni3Zr/γ-Al2O3 (ICP) had relatively high activity in syngas methanation and the water gas shift (WGS) reaction. A high CO conversion, ∼91.2%, was obtained at 325 °C under 1.5 MPa pressure, with a syngas flow of 10,000 mL g−1 h−1. However, the selectivity of CH4 over 25Ni3Zr/γ-Al2O3 (ICP) was 85.2%, which was slightly lower than that of 25Ni3Zr/γ-Al2O3 (IP), because of enhancement of the WGS reaction. The catalysts were characterized using temperature-programmed reduction, X-ray diffraction, and transmission electron microscopy; the results indicated that Ni was well dispersed on the γ-Al2O3 support by the ICP method. Zr doping improved Ni dispersion and H2-promoted dissociation of CO. Furthermore, it was found that the larger amount of reducible Ni formed using the ICP method gave a better catalytic performance.

The catalyst 25N3ZA prepared by impregnation co-precipitation(ICP) shows higher activity of methanation than that of impregnation (IP), and its CO conversion of CO was as high as 91.2% at reaction conditions of 325 °C, 10,000 mL g−1 h−1 and 1.5 MPa. Superior performance can be attributed to (i) better dispersion of Ni on the γ-Al2O3 support by ICP; (ii) Zr doping improved the dispersion of Ni as well the hydrogen-promoted dissociation of CO.Figure optionsDownload as PowerPoint slide