Stability of Ni and Rh–Ni catalysts derived from hydrotalcite-like precursors for the partial oxidation of methane

In this work, NiMgAl and RhNiMgAl catalysts prepared from HTLCs precursors were investigated for the Partial Oxidation of Methane (POM) at 550 and 750 °C. Samples have been characterized by XRD, TPR, H2 chemisorption, TPSR analyses, XPS, field emission scanning electron microscopy and Raman spectroscopy. NiMgAl catalysts with high Ni content (40 and 16 wt%) showed high stability and high methane conversion for POM. On the other hand those with lower Ni content (NiHT15 and NiHT25, with 6 and 4 wt%) exhibited low catalytic activity with low H2/CO ratio (<2) and fast deactivation. In RhNiHT25 (0.6 wt. % Rh), the Ni reducibility was improved, increasing the methane conversion and hydrogen selectivity. In addition, the noticeable increase in stability was related to the absence of carbon deposition after 30 h on stream at 550 °C. These results show that RhNiHT25 is promising for application in membrane reactors to produce high purity hydrogen.

► NiMgAl and RhNiMgAl catalysts were prepared from HTLC like precursors. ► The catalysts were tested for partial oxidation of methane at 750 and 550 °C. ► The Ni reducibility was improved due to the synergic effect between Rh and Ni. ► RhNiHT25 catalyst was very stable during at least 30 h of reaction. ► RhNiHT25 is promising for application in membrane reactors.