High carbon-resistant nickel supported on yttria–zirconia catalysts for syngas production by dry reforming of methane: The promoting effect of cesium

Dry reforming of methane (DRM) is a highly researched process for conversion of methane into syngas that consumes the greenhouse gas (CO2). In this work, the promotional effect of cesium on yttria-zirconia-supported nickel catalysts is studied, for the first time, in DRM. Cs loading was varied from 0.5 to 4.0 wt% and fresh materials were characterized by N2 sorption, XRD, TPR, and TEM, while spent catalysts were examined by TEM, Raman spectroscopy, and TGA after catalytic testing. Interestingly, cesium improved carbon resistance of the catalysts. It was shown that addition of up to 1.0 wt% Cs resulted in formation of 13–14 nm nanoparticles in strong interaction with the support, which prevented their sintering during reaction. In this case, hydrogen yield exceeded 75% after 420 min on stream, and this value was higher than those reported in literature for the same loading of other promoters like cerium and barium. However, as the amount of cesium surpassed 1.0 wt%, catalytic performance was lowered, even below that of Cs-free sample and this can be assigned to a possible coverage of active sites by excess cesium. An optimum range of 0.5–1.0 wt% was thus determined for a good performance in dry reforming of methane.