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## The activity of carbon supported large ruthenium crystallites in carbon monoxide methanation

#### Abstract

Summary In the beginning of the twentieth century, French chemist Paul Sabatier discovered catalytic hydrogenation of carbon dioxide producing methane and water, later named Sabatier reaction. Today this reaction as well as the conversion of carbon monoxide into methane is called methanation [1]. The methanation of COx is used to remove CO, which poisons the iron catalyst, from synthetic gas used for the production of ammonia. The reaction is also used in the analysis of the traces of COx and in the production substitute natural gas (SNG) from CO2. Methanation of COx is used in many important industrial processes, thus numerous studies on the catalysts of this reaction are being done. The reaction is catalyzed among others by nickel, ruthenium and Ni-La2O3-Ru phase. The efficiency of methanation depends on the activity of the catalyst, which depends on the composition and porosity of the support and the surface area of the active phase [1]. Research has proven, that the activity of nickel and ruthenium catalyst supported on alumina used in the methanation of COx is inversely proportional to the size of the crystallites of the metal [2]. This thesis investigates this relation regarding carbon supported ruthenium catalyst. Three catalysts which differed in the size of metal crystallites were prepared. This difference was achieved by the use of carbon supports modified at high temperatures. The portions of carbon were modified in the atmosphere of helium, under pressure of 400 Pa, at 1600°C, 1900°C and 2300°C respectively. Higher purity and partial graphitization of the carbon support, which decreased its susceptibility to methanation, was achieved in the process [8]. Subsequently support samples were impregnated in the water-acetone solution of the active phase precursor- RuCl3•0,5H2O and left in a vacuum desiccator overnight at room temperature and pressure of 6 kPa. Later the solvents were evaporated using vacuum evaporator, and the catalysts were reduced, cooled down and passivated afterwards. The sizes of the ruthenium crystallites were calculated using x-ray diffraction (XRD), which was also used to identify phases in the catalyst samples, and chemisorption. The activity of the catalysts was measured at 220°C, 240°C and 270°C. The composition of the methanation products was analyzed using gas chromatograph with flame-ionization detector (FID). The XRD studies confirmed that the examined samples consisted of graphite and ruthenium. They also showed that the average size of the metal crystallites in each catalyst was diversified (4,15 nm, 6,5 nm, 8,75 nm), which satisfied the assumptions of the preparation of the catalysts. Moreover the average size of the ruthenium crystallites calculated from the chemisorption data was 3,63 nm, 6,81 nm and 8,42 nm, which agreed with the XRD results. Methanation rate constant, which is the measure of the activity of the examined catalysts, was calculated from the data acquired via catalytic activity tests. The catalyst with the medium-size ruthenium crystallites (about 6,5 nm) exhibited the highest activity in the methanation of CO regardless of temperature, therefore there might be an optimal size of the metal crystallites at which the maximum activity of carbon supported ruthenium catalyst is observed.
Diploma type
Engineer's / Bachelor of Science
Diploma type
Engineer's thesis
Author
Title in Polish
Aktywność dużych krystalitów rutenu osadzonych na węglu w reakcji metanizacji tlenku węgla
Supervisor
Elżbieta Truszkiewicz (FC/CChT) Elżbieta Truszkiewicz,, 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
22-01-2016
Issue date (year)
2016
Reviewers
Tomasz Gołofit (FC/DH-EM) Tomasz Gołofit,, Department Of High-Energetic Materials (FC/DH-EM)Faculty of Chemistry (FC) Elżbieta Truszkiewicz (FC/CChT) Elżbieta Truszkiewicz,, Chair of Chemical Technology (FC/CChT)Faculty of Chemistry (FC)
Keywords in Polish
Metanizacja CO,katalizator rutenowy, rozmiar krystalitów, aktywność katalityczna, węgiel aktywny
Keywords in English
CO methanation, ruthenium catalyst, size of crystallites, catalytic activity, activated carbon
Abstract in Polish
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Identyfikator pracy APD: 8452

Uniform Resource Identifier
https://repo.pw.edu.pl/info/bachelor/WUT035e940695ca478e92fbe2760b18d6e2/
URN
urn:pw-repo:WUT035e940695ca478e92fbe2760b18d6e2

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