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Catalytic NO decomposition on LaSrMn1− xNi xO4 +δ (0 ≤ x ≤ 1) is investigated. The activity of NO decomposition increases dramatically after the substitution of Ni for Mn, but decreases when Mn is completely replaced by Ni ( x = 1.0). The optimum value is at x = 0.8. These indicate that the catalytic performance of the samples is contributed by the synergistic effect of Mn and Ni. O2-TPD and H2-TPR experiments are carried out to explain the change of activity. The former indicates that only when oxygen vacancy is created, could the catalyst show enhanced activity for NO decomposition; the latter suggests that the best activity is obtained from catalyst with the most matched redox potentials (in this work, the biggest Δ T and Δ E values). The close relationships between activity and Δ T or Δ E indicate that Δ T and Δ E are important parameters of catalyst for NO decomposition. [ABSTRACT FROM AUTHOR]

Abstract: Ce and MgO were added simultaneously to La–Sr–Ni–O catalyst and a substantial enhancement of activity for NO decomposition was observed, which may be attributed to the formation of a new highly active site caused by the addition of Ce and MgO. [Copyright &y& Elsevier]

Abstract: Fe–Ni–O samples, with Fe/Ni ratio ranging from 2 to 1/3, were synthesized. Samples synthesized with and without citric acid in the precursor were compared and it was found that the addition of citric acid is the necessary condition for FeNi3 formation; it was found that FeNi3 alloys were formed in these samples even when calcined in an air atmosphere. X-ray diffraction and X-ray photoelectron spectroscopy measurements were used to characterize the samples. Because of the existence of FeNi3 alloys, Fe–Ni–O samples showed strong reactivity to NO and NO+O2 but were inert to O2 alone. [Copyright &y& Elsevier]

Abstract: Perovskite-type oxide La0.4Sr.6Mn0.8Ni0.2O3 showed high activity for NO decomposition and thus was taken as the catalyst for investigation. Based on the ‘recycle’ mechanism of NO decomposition (NO2 acts as an intermediate of O2 formation) we reported recently, the kinetics of NO decomposition over La0.4Sr.6Mn0.8Ni0.2O3 was investigated. The NO decomposition rate was practically first-order for NO in the range 0.5–2.0vol.% NO/He, while the reaction order varied from −0.24 to −0.08 for O2 (0–6vol.% O2/He), depending on the temperature. The kinetics deduced from the ‘recycle’ mechanism accords well with that observed in practice by introducing the item K −6 (K −7)1/2 P NO ()1/2, which reflects the reciprocity of O2 and NO in the reaction and is introduced in the kinetics for the first time. The rates and NO2 dissociation equilibrium constants calculated from the practical reaction certified that NO2 dissociation is indeed an important step of NO decomposition, and hence suggested that the ‘recycle’ mechanism is believable. [Copyright &y& Elsevier]

Abstract: Effect of cerium ions on the activity of La1−x Ce x SrNiO4 (0≤ x ≤0.3) for NO decomposition was investigated both in the absence and presence of oxygen. The amount of Ce in the frame reached 30at.% (x =0.3) in the present case without destroying the matrix structure. The Ce-substituted samples showed high activity for NO decomposition not only in the absence of O2 but also in the presence of O2, and the specific activity reached 1.59μmols−1 m−2 even 6.0%O2 was fed to the reactant gas (La0.7Ce0.3SrNiO4, T =1123K), indicating that the Ce addition can enhance the oxygen forbearance of catalyst. In addition, a new highly active site, which facilitates oxygen mobilization and desorption, might be formed in the sample due to the Ce addition, which thus resulted in the high activity for NO decomposition. [Copyright &y& Elsevier]

Abstract: NO decomposition reaction was investigated over La2−x Th x CuO4, in which the valence of copper was controlled by Th substitution and was characterized by XPS measurement. A close correlation between the valence of copper and the activity was observed. The activity increased with the decrease of the average oxidation number of copper, and increased with the increase of Cu+ content, suggesting that the transition metal with low valence (Cu+) is active for the reaction in the present cases. [Copyright &y& Elsevier]

Abstract: Compound of La2−x Sr x CuO4 (x ≥0.5) with T* phase structure were prepared by conventional citric method. The split peak at 2θ =∼31° in XRD patterns and the broad absorption band at 680cm−1 with a shoulder peak at 620cm−1 in IR spectra suggested the formation of T* phase in La2−x Sr x CuO4 compounds at x ≥0.5. The amount of sample with T* phase structure increased with the increase of Sr content as certified by XRD patterns. Catalytic performance of La2−x Sr x CuO4 for NO decomposition was investigated, and it was found, by correlating the solid-state properties and the activity of NO decomposition, that the presence of T* phase structure enhanced the catalytic activity of La2−x Sr x CuO4 in NO decomposition. [Copyright &y& Elsevier]

Abstract: Catalytic reduction of NO by CO was studied over perovskite-like La2−x Sr x CuO4 (x =0.0, 0.5, 1.0) catalysts prepared by citrate method and calcined at 900°C. The catalysts were characterized by O2-TPD, H2-TPR and cyclic voltammetry (CV) measurements. Results obtained from CV were in well agreement with those obtained from O2-TPD and H2-TPR, suggesting that CV is also a powerful means in the study of heterogeneous catalytic reaction carried out at high temperatures. In O2-TPD experiment, the desorption area of β oxygen, which was contributed by the oxygen adsorbed on the oxygen vacancy, increased with the increase of Sr content and was in the same order as the activity, indicating that the activity depended largely on the oxygen vacancy resulted by Sr addition. In H2-TPR measurements, the increasing area of the first reduction peak indicating that the oxygen vacancy resulted by Sr addition plays important role in this peak, since the Cu3+ content in La1.5Sro.5CuO4 and LaSrCuO4 is the same. And in the CV curves, the area of redox peak, which represents the amount of oxygen vacancy participating in the reaction, has close correlations with the activity of NO+CO reaction, while the symmetry of redox potentials does not contribute much to the activity. Overall, with the link of oxygen vacancy, CV was introduced and has obtained great success in explaining reaction in heterogeneous catalysis. Besides, from the result that none reductive peak was observed in the first CV curves of LaSrCuO4, it suggested that the first step of a catalytic reaction is reduction, corresponding to the oxidation of catalyst i.e., M n+(Cu2+)→M(n+1)+(Cu3+). [Copyright &y& Elsevier]