Temperature-programmed reduction of CoOAI2O3 catalysts
TL;DR: In this article, it was shown that temperature-programmed reduction (TPR) is a sensitive technique for the characterization of Co and Co-Aloxidic phases in CoOAl2O3 catalysts.
About: This article is published in Journal of Catalysis.The article was published on 1985-05-01. It has received 611 citations till now. The article focuses on the topics: Temperature-programmed reduction & Qualitative inorganic analysis.
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TL;DR: The as-prepared cobalt oxide (assigned as CoO x ) was fabricated by precipitation-oxidation from aqueous cobalt nitrate solution using sodium hydroxide and oxidation with hydrogen peroxide as mentioned in this paper.
707 citations
TL;DR: In this paper, the causes of deactivation and the influence on reaction rate are discussed and methods for minimising catalyst deactivation, by tailoring catalyst properties and/or process operations, are presented.
Abstract: Catalyst deactivation is usually inevitable, although the rate at which it occurs varies greatly. This article discusses the causes of deactivation and the influence on reaction rate. Methods for minimising catalyst deactivation, by tailoring catalyst properties and/or process operations, are presented, as well as reactor configurations suitable for the regeneration of deactivated catalysts. Alkane dehydrogenation is used as an example to demonstrate the variety of engineering solutions possible.
639 citations
TL;DR: Manganese oxides of different crystallinity, oxidation state and specific surface area have been used in the selective catalytic reduction (SCR) of nitric oxide with ammonia, indicating a relation between the SCR process and active surface oxygen.
Abstract: Manganese oxides of different crystallinity, oxidation state and specific surface area have been used in the selective catalytic reduction (SCR) of nitric oxide with ammonia between 385 and 575 K. MnO2 appears to exhibit the highest activity per unit surface area, followed by Mn5O8, Mn2O3, Mn3O4 and MnO, in that order. This SCR activity correlates with the onset of reduction in temperature-programmed reduction (TPR) experiments, indicating a relation between the SCR process and active surface oxygen. Mn2O3 is preferred in SCR since its selectivity towards nitrogen formation during this process is the highest. In all cases the selectivity decreases with increasing temperature. The oxidation state of the manganese, the crystallinity and the specific surface area are decisive for the performance of the oxides. The specific surface area correlates well with the nitric oxide reduction activity. The nitrous oxide originates from a reaction between nitric oxide and ammonia below 475 K and from oxidation of ammonia at higher temperatures, proven by using 15NH3. Participation of the bulk oxygen of the manganese oxides can be excluded, since TPR reveals that the bulk oxidation state remains unchanged during SCR, except for MnO, which is transformed into Mn3O4 under the applied conditions. In the oxidation of ammonia the degree of oxidation of the nitrogen containing products (N2, N2O, NO) increases with increasing temperature and with increasing oxidation state of the manganese. A reaction model is proposed to account for the observed phenomena.
634 citations
TL;DR: The two main advantages of catalytic combustors over flame combustors apply to these goals: Catalytic combustion can be carried out over a wide range of fuel concentrations in air and at low temperatures as mentioned in this paper.
Abstract: Catalytic combustion, as an alternative to conventional thermal combustion, has received considerable attention during the past decade. Research efforts have been promoted by the need to meet governmental demands concerning pollution and the wish to use energy sources more efficiently. The two main advantages offered by catalytic combustors over flame combustors apply to these goals: Catalytic combustion can be carried out over a wide range of fuel concentrations in air and at low temperatures. These low temperatures result in attaining NO, emission levels substantially lower than possible with conventional combustors.
626 citations
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TL;DR: In this paper, the structure and type of phases present in sulfided alumina-supported, as well as unsupported, Co-Mo catalysts is obtained from in situ Mossbauer emission spectroscopy (MES) studies.
563 citations
TL;DR: In this paper, the molar enthalpy of interchange of ions on tetrahedral sites with ions on octahedral sites was calculated from cation distribution data known at a single temperature for each spinel.
526 citations
TL;DR: In this article, a series of sulfided Co-Mo Al 2 O 3 catalysts with different Co Mo ratios but with constant molybdenum content was investigated, and it was shown that the relative amounts of the three phases depend strongly on the Co Mo ratio.
354 citations