Catalytic activity of hydrotalcite-derived catalysts in the dry reforming of methane: on the effect of Ce promotion and feed gas composition

Ni/Al and Ni/Mg/Al hydrotalcite-derived materials containing various Ni loadings were synthesized and subsequently promoted with Ce-species via adsorption from [Ce(EDTA)]-complexes. The obtained materials were characterized by elemental analysis (ICP-MS), XRD, H-2-TPR, CO2-TPD, TG and low temperature N-2 sorption experiments. The amount of the introduced Ce was dependent on the nickel and magnesia content in catalysts precursors, and it influenced materials properties (i.e. basicity, reducibility of Ni species) in various ways and the catalytic performance in the dry reforming of methane (DRM). The promoted catalysts showed improved performance with CH4 and CO2 conversions at 550 degrees C in the range of 35-55 and 35-45%, respectively. The extent of the improvement was dependent on the nickel content and the presence of magnesia. In general, Ce promotion increased materials stability by changing of the type of carbonaceous deposits. Ce modification hindered the transformation of amorphous carbonaceous deposits to graphitic carbon. The former may be easier oxidized and contribute to syngas production. Two selected catalysts were additionally tested in DRM at elevated temperatures (650 and 750 degrees C) and over various feed gas compositions.