Decomposition of Nitrous Oxide on CoOX/ZrO2, CuOX/ZrO2 and FeOX/ZrO2 Catalysts (original) (raw)
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Direct nitrous oxide decomposition with a cobalt oxide catalyst
Applied Catalysis A: General, 2010
The influence of individual components of the gas mixture, which is found directly downstream of the platinum-rhodium gauze in ammonia oxidation, i.e. nitric oxide, oxygen and water vapor, on the state of Co 3 O 4 under high-temperature nitrous oxide decomposition conditions has been determined. A variety of characterization techniques, such as: nitrogen physisorption, XRD, XPS and TG-DTA-MS, was applied.
Direct nitrous oxide decomposition with CoOx-CeO2 catalysts
Applied Catalysis B: Environmental, 2011
The focus of the performed studies were CoO x -CeO 2 oxide catalysts for nitrous oxide decomposition. All CoO x -CeO 2 systems exhibit similar or higher activity than the undoped cobalt catalyst. It has been found that in temperatures up to 800 • C in a N 2 O-Ar stream cobalt in these catalysts is in the form of Co 3 O 4 . At higher temperatures it is reduced to CoO. In a N 2 O-O 2 -Ar stream Co 3 O 4 is the main cobalt-containing phase in the entire studied temperature range. The obtained results revealed that the activity of CoO x -CeO 2 systems with a high cobalt loading increases with temperature only up to 800 • C in a N 2 O-Ar stream. Upon further temperature increase the activity of these catalysts decreases, as in the case of the undoped cobalt catalyst. This is due to the reduction of Co 3 O 4 to CoO. Hence, when oxygen is present in the feed and cobalt is in the form of Co 3 O 4 , the activity is higher. In contrast, the activity of catalysts with the cobalt molar ratio no greater than 0.64 is the same in both N 2 O-Ar and N 2 O-O 2 -Ar streams and increases with temperature in the entire studied range (700-850 • C). It has been demonstrated that at 850 • C in a N 2 O-Ar stream CoO x -CeO 2 systems contain two types of CoO, which require different conditions to be oxidized. This is a result of a different strength of interaction with CeO 2 . It can be concluded that the activity of CoO x -CeO 2 systems results from the activity of Co 3 O 4 and of the cobalt oxide-ceria interface. The share of each component is determined by the cobalt content.
Indonesian Journal of Computing, Engineering and Design (IJoCED), 2019
Decomposition of nitrous oxide (N2O) over titania (TiO2) supported copper (Cu) catalyst was investigated with the existence of oxygen and water vapor. The catalytic activity of TiO2 was promoted by copper loading. It was found that there are optimum levels of copper loading on TiO2, and these values are correlated to the specific surface area of TiO2 support being used. The relationship between the catalytic activity for decomposition of N2O and the crystal structure of TiO2 was also investigated. The result revealed that Cu/TiO2 catalysts with the rutile structure has a higher activity toward N2O decomposition than those with the anatase structure. In this research, Cu(5wt%)/TiO2 prepared from TiO2 JRC-TIO-4 (reference catalyst provided by Catalysis Society of Japan) which was mainly constituted of rutile showed the highest activity for N2O decomposition and it could decompose N2O completely at 650℃. The catalytic activity was inhibited by the existence of oxygen. However, there wa...
The Influence of Water Vapor and Sulfur Dioxide on the Catalytic Decomposition of Nitrous Oxide
Chemical Engineering & Technology, 2001
In a catalysts screening for the nitrous oxide decomposition, three groups of catalysts (metals on supports, hydrotalcites, and perovskites) were studied relating to their activity in the presence of vapor or sulfur dioxide, in the temperature range from 200 to 500 C. It was found that the water vapor strongly inhibates the nitrous oxide decomposition at T = 200±400 C. The sulfur dioxide poisons the catalysts, in particular the perovskites. The catalysts Rh-ZrO 2 and Ex-Co, Rh-Al-HTlc are potentially suitable for the nitrous oxide decomposition in exhaust gas at around T = 500 C.
A study on N2O catalytic decomposition over Co/MgO catalysts
Journal of Hazardous Materials, 2009
a b s t r a c t Different oxide supported cobalt catalysts were prepared by co-precipitation method and tested for the decomposition of nitrous oxide. Co/MgO with cobalt loading of 15% showed the best activity and a 100% N 2 O conversion was obtained at temperatures higher than 700 K. The active phase of cobalt species in Co/MgO catalysts was Co 3 O 4 highly dispersed in the matrices of MgO, based on XRD and XPS results as well as the kinetic analysis. The existence of NO, O 2 and H 2 O in reaction system showed different negative effects on N 2 O decomposition. Nevertheless, a 100% N 2 O conversion could be achieved at 800 K under simulated conditions of tail gas from nitric acid plant. Moreover, Co/MgO catalyst exhibited quite good durability and no obvious activity loss was observed in the 100 h stability test.
Fe2O3/Al2O3 catalysts for the N2O decomposition in the nitric acid industry
Catalysis Today, 2008
Fe 2 O 3 catalysts supported on Al 2 O 3 were used to remove nitrous oxide from the nitric acid plant simulated process stream (containing O 2 , NO and H 2 O). Catalysts were prepared by the coprecipitation method and were characterized for their physico-chemical properties by BET, XRD, AFM and TPR analysis. A strong influence of the post-preparation heating conditions on the structural and catalytic properties of the catalysts has been evidenced. Laboratory tests revealed 95% conversion of N 2 O at temperature 750 8C and a slight decrease in activity in the presence of H 2 O and NO. The catalysts were inert towards decomposition of NO. The pilot-plant reactor and real plant studies (up to 3300 h time-on-stream) confirmed high activity and very good mechanical stability of the catalysts as well as no decomposition of nitric oxide.
Cobalt Species Active for Nitrous Oxide (N2O) Decomposition within a Temperature Range of 300–600°C
Australian Journal of Chemistry, 2017
This article presents a novel study of the role of the catalyst support towards the formation of active cobalt sites for N 2 O conversion reactions within a temperature range of 300-6008C. These reactions were examined in a fixed bed tubular reactor. ZSM-5 (Si/ Al ¼ 15), TS-1, and amorphous silicates were used as catalyst supports for cobalt loadings. All catalysts were prepared by following standard methods and recipes. In general, cobalt loading on supports was varied between 0.78 and 5.40 wt.-% (as determined from inductively coupled plasma (ICP) analysis). ICP, temperature programmed desorption, X-ray diffraction, and N 2 adsorption/desorption isotherms were used for the characterization of prepared catalysts. Cobalt on ZSM-5 support generates weak and strong acid sites. Furthermore, for the Co-ZSM-5 catalyst, prepared by a wet deposition method, the N 2 O decomposition reaction is first order with an activation energy of ,132 kJ mol À1. Co 2þ and Co 3þ are the suggested active species for the N 2 O conversions in the studied range of temperatures.
Journal of Environmental Chemical Engineering, 2015
The de-N 2 O performance of low content (0.25, 0.5 and 1.0 wt. %), Al 2 O 3 supported noble metals (Pt, Pd, Ir) is comparatively explored in the present study. Several parameters related to the effect of temperature, metal content and feed composition are investigated. An extensive characterization study involving BET, TPR, XRD and TEM was also carried out to reveal the impact of metal entity and content on the structural, morphological and redox characteristics of the catalysts. The results imply that the de-N 2 O performance is in general increased upon increasing metal loading, a fact being more intense over Ir-based catalyst. Under oxygen deficient conditions N 2 O conversions as high as ~100% and ~80% are reached at 600 o C over Ir-and Pd-based catalysts, respectively, instead of ~30% achieved over Pt-based catalysts. A moderate deactivation in oxygen excess conditions is observed with Ir and Pd catalysts, while Pt-based catalysts are totally deactivated. The enhanced de-N 2 O performance of Ir-, Pd-based catalyst can be mainly interpreted taking into account the formation of active metal oxide phases, not easily susceptible to oxygen poisoning.
Catalyzed decomposition of N2O on metal oxide supports
Applied Catalysis B: Environmental, 1997
The catalytic decomposition of N20 using metal oxides supported on silica, magnesium oxide, calcium oxide and hydrotalcite-like supports was studied. Co0 is much more active than CuO and Fe20s when supported on silica. A conversion of 95% was achieved using Co0 on Si02 at 1500 hh' GHSV, 500°C and 50,000 ppm feed N20. However,the use of higher flow rates resulted in lower conversions. We found that when supporting Co0 on MgO, a much more active catalyst is attained. A conversion of 95% was achieved using this catalyst at 40,000 h-l, 5OO"C, 100,000 ppm N20 feed. This is a significant improvement over any catalyst currently in the literature. The activity of this catalyst was decreased by calcination at 1000°C. XPS and XRD studies revealed that higher temperature calcination led to an inactive crystalline phase. The active catalyst displayed a less crystalline phase involving the support and the metal oxide. Other oxide combination catalysts were found to be less active than the CoO/MgO catalyst. Based on our findings, a modification of the reactions proposed for NaO decomposition is suggested.
Applied Catalysis B: Environmental, 1996
PbO-ZrO, catalysts have been prepared by sequential impregnation/calcination onto Al,O, support for high concentration N,O (27.97 mol%) decomposition. The p-block-element involved material system has been investigated with GC, BET, DTA, XRD and catalytic activity evaluation. It is found that with an atomic ratio Pb:Zr = I:6 the material system shows the best catalytic performance for the decomposition. The catalyst with this composition has a tetragonal phase of ZrO, over reaction temperatures. The catalytic activity observed can be attributed to the presence of Pb cations with mixed valence states in tetragonal ZrO, lattice. Doping gases such as H,O, CO,, and 0, are also mixed into the N,O and studied. It is found that N,O adsorption is rate-limiting step for the decomposition reaction. The reaction can be described as first order with respect to partial pressure of N,O, considering that decomposition product 0, exhibits no inhibition effect on the reaction in high conversion region.