Vanadium-modified LaNiO3 perovskites for preferential CO oxidation in H2-rich streams: effect of V content on redox behavior, apparent kinetics, and selectivity

Abstract The effect of nominal partial replacement of Ni by vanadium on the structural, redox, and catalytic properties of LaNiO 3 -based perovskites was investigated for preferential CO oxidation in H 2 -rich streams (CO-PROX). LaNi 1 -x V x O 3 materials (x = 0, 0.05, and 0.10) were prepared by a modified citrate route and characterized by XRF, N 2 physisorption, XRD, H 2 -TPR, Raman spectroscopy, and in situ DRIFTS. V modification increased the BET surface area from 4 m 2 g −1 for LaNiO 3 to 17 and 20 m 2 g −1 for the 5 and 10% V samples, while decreasing the LaNiO 3 crystallite size from 9.7 to about 7 nm. The V-containing samples also exhibited additional high-temperature reduction features, indicating modified redox behavior rather than a general enhancement in reducibility. The 5% V sample showed the highest CO consumption rate at 225 °C (8.82 × 10 −7 mol g cat −1 s −1 ) and the lowest apparent activation energy (37.8 kJ mol −1 ), whereas increasing V content to 10% provided no further kinetic benefit. During 24 h at 300 °C, CO conversion increased for LaNiO 3 and the 5% V sample while CO 2 selectivity progressively decreased. In situ DRIFTS showed the emergence of CH 4 − and CH x -related species at elevated temperature, consistent with an increasing contribution of hydrogenation pathways. Overall, moderate V modification provided the most favorable apparent kinetic response, but did not prevent the pronounced loss of CO 2 selectivity during prolonged operation at 300 °C.