Surface basicity and catalytic performance on Ni/Ce-Zr-Al-O catalyst for CO2+CH4 reforming

Ni/Ce-Zr-Al-O catalysts were prepared by hydrothermal synthesis method. The effect of NiO content on the basicity of catalyst was investigated by using H-2-TPD (temperature programmed desorption), DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy), and CO2-TPD. The catalytic performance was tested and the amount of coke deposition was measured. The H-2-TPD result shows that the amount of Ni on the catalyst surface increases with the NiO content. DRIFT and CO2-TPD results show that the bicarbonate and carbonate are the predominant species of the CO2 chemisorptions. The addition of few Ni can promote obviously CO2 chemisorption and weaken the intensity of basicity. While Ni metal is preferable to reside on stronger basic site, the increase of NiO content can weaken the basicity, decrease the amount of basic site and weaken the CO2 adsorption performance. It weakens the performance of eliminating coke by mobile oxygen originated from CO2. So the catalytic activity of the sample with 7.0% (w) NiO decreases during reaction, the amount of coke deposition is much higher than that of the sample with 4.0% (w) NiO.