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## Effect of potassium on the activity of cobalt catalysts for ammonia synthesis

### Klaudia Kozera

#### Abstract

Basics of ammonia synthesis reaction from elements dates back to the end of eighteenth century. The indication of appropriate reaction conditions took over a hundred years. It was found that conducting the reaction with a satisfactory efficiency requires the use of high temperature, high pressure and the presence of active catalyst. In 1913 the first factory of ammonia synthesis was built (in Oppau in Germany), it produced 30 tons of NH3/day. It was a result of the collaboration with F. Haber and C. Bosch, who developed technological basics of NH3 synthesis. The fused iron doped with other elements (such as calcium and aluminum in oxide forms) was used as a catalyst in the first ammonia synthesis installation. Since then, ammonia synthesis technology has been still modernized in order to reduce energy consumption and to increase the process efficiency [1]. One of the directions of improvements is searching for a new, improved catalyst. The fused iron catalyst is still commonly used in industrial NH3 synthesis installation, although the formula has changed over the years. However, it has a low activity at high conversion degrees. In the twentieth century a carbon supported ruthenium catalyst become an alternative to the iron catalyst. However, a high price of ruthenium and a possibility of the carbon support destruction as a result of its methanation in H2, cause that it is not widely used catalyst [2]. Among catalysts known in the literature, the one with cobalt as an active phase and cerium as one of the promoters is particularly interesting [3]. The aim of the work was to determine the effect of potassium on the catalytic properties of cobalt catalysts promoted with cerium. The precursor of the cobalt catalyst were prepared by co-precipitation and catalysts with a various content of potassium were prepared by impregnation. In order to determine the composition of the oxide precursor thermogravimetric analysis coupled with mass spectrometry was carried out. ICP-OES analysis (inductively coupled plasma optical emission spectroscopy) was made to determine the amount of potassium in the oxide precursor sample (a reference sample). A specific surface area of the oxide precursor and the catalyst precursors were measured with the use of N2 physisorption. H2 chemisorption measurements were carried out to examine a surface area of an active phase (metallic cobalt) of catalysts. The activity of obtained catalysts in ammonia synthesis was measured also (T=400, 430, 470°C, p=6.3 MPa, H2:N2=3:1).The obtained results allowed to conclude that the addition of potassium in a small amount (0.3 wt% K2O in relation to the mass of Co3O4) to the oxide precursor does not change the activity of the catalyst in ammonia synthesis. In contrast, catalysts containing 2.0 and 4.0 wt% K2O have lower activity in ammonia synthesis (T=400°C) by about 67% and 86%. 1. W. Bobrownicki, S. Pawlikowski, „Technologia związków azotowych”, WNT Warszawa 1974. 2. Z. Mordecka, A. Gołębiowski, W. Hennel, S. Mordecki, Przem. Chem. 83(1) (2004) 32. 3. W. Raróg- Pilecka, E. Miśkiewicz, Z. Kowalczyk, Catal. Commun. 9 (2008) 870.
Diploma type
Engineer's / Bachelor of Science
Diploma type
Engineer's thesis
Author
Klaudia Kozera (FC) Klaudia Kozera,, Faculty of Chemistry (FC)
Title in Polish
Wpływ zawartości potasu na aktywność katalizatorów kobaltowych do syntezy amoniaku
Supervisor
Wioletta Raróg-Pilecka (FC/CChT) Wioletta Raróg-Pilecka,, Chair of Chemical Technology (FC/CChT)Faculty of Chemistry (FC)
Certifying unit
Faculty of Chemistry (FC)
Affiliation unit
Chair of Chemical Technology (FC/CChT)
Study subject / specialization
, Technologia Chemiczna
Language
(pl) Polish
Status
Finished
Defense Date
04-02-2016
Issue date (year)
2016
Reviewers
Aldona Zalewska (FC/CofIC) Aldona Zalewska,, Chair Of Inorganic Chemistry (FC/CofIC)Faculty of Chemistry (FC) Wioletta Raróg-Pilecka (FC/CChT) Wioletta Raróg-Pilecka,, Chair of Chemical Technology (FC/CChT)Faculty of Chemistry (FC)
Keywords in Polish
wpływ, katalizator, faza aktywna, kobalt, promotory cer, potas, współstrącanie, aktywność.
Keywords in English
effect, catalyst, active phase, cobalt, promoters, cerium, potassium, co-precipitation, activity.
Abstract in Polish
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Identyfikator pracy APD: 8445

Uniform Resource Identifier
https://repo.pw.edu.pl/info/bachelor/WUTc4336f4491624090a2a40e22c36a9796/
URN
urn:pw-repo:WUTc4336f4491624090a2a40e22c36a9796

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