Carbon deposition and catalytic performance evaluation of supported NiCu single atom alloy in the dry reforming of methane

Abstract

Recent technological advances turned feasible the synthesis of catalysts with their active phase atomically dispersed. CuMgAl hydrotalcite-derived mixed-oxide supported NiCu catalysts were prepared by the modified galvanic replacement, with 8% Cu and Ni/Cu molar ratio of 0.1, 0.01, 0.002, and 0.001. The catalysts were characterized by EDS, XRD, TGA, TPR, H2 chemisorption, TPD-CO2, DRIFTS, and SEM. DRIFTS and H2 chemisorption indicated the presence of Ni atomic species in Ni0.002Cu/CuMgAl and Ni0.001Cu/CuMgAl catalysts. All catalysts were tested in the dry reforming of methane at 800 °C and 100 mL min−1 (1:1:0.5 CH4:CO2:N2). Ni0.1Cu/CuMgAl presented the highest activity, with a 39% CH4 conversion and 143 s−1 TOF. The catalysts presented a significant deactivation further investigated by TGA, SEM, and Raman spectroscopy. Over 1.0 mgC/mgcat was deposited in every catalyst except Ni0.1Cu/CuMgAl. A higher formation of amorphous carbon was observed. The difference in carbon species could be evaluated. Cu sintering was also observed.