The influence of alkaline promoters on the properties of the Ni/HAp catalyst in the methane dry reforming reaction

The reforming of methane with carbon dioxide is still of great interest due to the ever-increasing demand for synthesis gas and hydrogen. This process makes it possible to use two major gases that are considered harmful to the environment. The main problem for its commercial application is the lack of a catalyst that is both active, selective towards syngas (a mixture of hydrogen and carbon monoxide) and resistant to deactivation by coke deposition. Nickel is the most commonly used metal in methane reforming reactions due to its high activity and reasonable price. But still there is a gap in the literature for research on novel catalysts and their properties modifications devoted to strategies to reduce deactivation of the catalysts caused by the coke formation. In the present work a series of hydroxyapatite supported nickel catalysts promoted by alkali metals (Li, Na, K and Cs) were tested. The surface and structural properties of the catalysts were well characterized by physicochemical methods. Activity and selectivity were measured at 600 oC for 20 hours’ time-on-stream test. Resistance to coking was measured with Magnetic Suspension Balance. The stability of the catalyst was improved by the addition of promoters, which reduced the rate of coking. In particular, the cesium-promoted Ni/HAp catalyst significantly inhibited coke deposition, while slightly reducing methane conversion and selectivity to hydrogen.