Study of La2−xCaxCuO4 perovskites for the low temperature water gas shift reaction

The effects of small fractions of calcium (x = 0, 0.05, 0.1, 0.15, and 0.20) on the structure and the catalytic properties of La2−xCaxCuO4 peroviskites have been investigated. The samples have been synthesized using the co-precipitation method. Perovskite-type oxides were characterized by XRD, TPR, XPS, XANES, SEM, and TEM. Catalytic tests for the water gas shift reaction (WGSR) were carried out in a tubular reactor at 290 °C. All samples showed a well-defined perovskite structure with surface areas between 6 and 18 m2 g−1. The partial substitution of La by Ca enhanced the stability of the perovskites and increased their reduction temperature. All catalysts were actives for WGSR, and the best catalytic performance was obtained for the La1.85Ca0.15CuO4 catalyst, but the samples with 5 and 10% of Ca had the best TOF values for reaction. These results can be associated to promoter effect of calcium, the high surface area, and the reducible species Cu0 and Cu1+.

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► La2−xCaxCuO4 samples were synthesized.
► This perovskites are active for the gas shift reaction at 290 °C.
► A promoter effect of Ca was observed.
► The best catalytic performance was obtained for the La1.85Ca0.15CuO4 catalyst.
► La1.85Ca0.15CuO4 catalyst presented the highest content of surface calcium and the reducible species Cu0 and Cu1+.