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Mixed oxide
About: Mixed oxide is a research topic. Over the lifetime, 5224 publications have been published within this topic receiving 115567 citations.
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TL;DR: In this article, the expected orthorhombic perovskite structure of the chromite is observed for all levels of substitution and maximum activity is achieved for the catalyst with x ǫ = 0.1 in which mixed oxide formation upon substitution of lanthanum by strontium in the chromites becomes maximised.
107 citations
TL;DR: In this article, a series of CexZr1−xO2 catalysts with 1.5% Pd were exposed to fixed exposures of SO2 under oxidizing environments and then characterized by FTIR, pulse-reactor studies with CO and O2, and temperature-programmed desorption (TPD).
Abstract: CeO2, ZrO2, and a series of CexZr1−xO2 catalysts with 1 wt.% Pd were exposed to fixed exposures of SO2 under oxidizing environments and then characterized by FTIR, pulse–reactor studies with CO and O2, and temperature-programmed desorption (TPD). For exposures above 473 K, sulfates were formed on all of the materials; however, the results are consistent with the formation of bulk sulfates on CeO2 and only surface sulfates on ZrO2. For the mixed oxides, the quantity of sulfates formed at 673 K increased linearly with the Ce content. In TPD, the sulfates on ZrO2 were stable to higher temperatures than those formed on CeO2, which decomposed in a well-defined peak between 900 and 1050 K. The sulfates on both oxides were reduced by CO above 750 K. Even though XRD patterns for the mixed oxide were significantly different from that of the physical mixture, the TPD and pulse–reactor results were similar to what would be expected for physical mixtures of CeO2 and ZrO2, suggesting that sulfate species are associated with individual metal cations. Finally, pulse–reactor studies with CO and O2 at 873 K show that the sulfates can be reversibly reduced and oxidized on both CeO2 and ZrO2, so that sulfur poisoning gives rise to an apparent increase in oxygen storage, demonstrating that this method is not acceptable for measurement of this quantity.
107 citations
TL;DR: In this paper, the authors performed the dehydrogenation of propane (PDH) to propylene in the presence of CO2 and found that the creation of surface metallic indium species during the reaction is crucial for the dehydrogenation performance.
106 citations
TL;DR: In this article, the results of long-term efforts aimed at research and development of industrial oxide catalysts for ammonia oxidation in the nitric acid production within two-bed (Pt gauzes+monolithic oxide layers) technology of the high pressure process are considered.
Abstract: This paper generalizes the results of long-term efforts aimed at research and development of industrial oxide catalysts for ammonia oxidation in the nitric acid production within two-bed (Pt gauzes+monolithic oxide layers) technology of the high pressure process. Main factors determining performance of precious metals and oxides in the high-temperature ammonia oxidation are considered. The surface oxygen bonding strength determined by the surface atomic structure appears to be the most important. From this point of view, existing approaches to synthesis of mixed oxide systems including perovskites with controlled nitric oxide selectivity and good stability in the high-temperature process of ammonia oxidation are analyzed. Main features of the bulk oxide monolithic catalysts production technology and principles of a two-bed system design based upon the process mathematical modeling are briefly outlined. Proven economic benefits of this technology recently commercialized in Russia at nitric acid plants are debated.
106 citations
106 citations