Barium-promoted Ru/carbon catalyst for ammonia synthesis: State of the system when operating

Truszkiewicz, Elżbieta; Raróg‐Pilecka, Wioletta; Schmidt‐Szałowski, K.; Jodzis, S.; Wilczkowska, Ewa; Łomot, Dariusz; Kaszkur, Zbigniew; Karpiński, Zbigniew; Kowalczyk, Z.

doi:10.1016/j.jcat.2009.04.024

Cited by 61 publications

(44 citation statements)

References 49 publications

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“…Since the ruthenium content is generally the same in all cases, the observed trend should be ascribed to the increase of the average size of ruthenium crystallites, or more directly -crystalline domains of ordered structure. The last one is a consequence of the support surface area, which determines ruthenium dispersion, as reported earlier for Ru/carbon catalysts dedicated for NH 3 synthesis [23]. Several methods can be applied to determine the domain size of nanoparticles [24,25].…”

Section: Catalyst Characterizationmentioning

confidence: 85%

The Effect of the Ruthenium Crystallite Size on the Activity of Ru/Carbon Systems in CO Methanation

et al. 2017

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interest recently because of its potential as a simple technique for CO removal from H 2 -rich feed gases for fuel cells [1,[3][4][5][6][7]. Due to the poor reserves of natural gas in some regions of the world, conversion of syngas from coal or biomass to synthetic natural gas (SNG) via the methanation reaction is also attracting great attention [8][9][10][11]. That is the reason why many groups are still working to obtain highly active and selective catalysts for that reaction.Supported Ni-based catalysts have been applied commercially on methanation due to their high activity, selectivity to CH 4 and low costs [1,8,11]. However, hydrogenation of CO x to methane can be catalyzed by several metals [12][13][14]. Some experimental works and density functional theory (DFT) calculations also indicate that ruthenium exhibits excellent activity in CO methanation [1,4,15,16]. Ruthenium dispersed on high-surface area oxide supports has been found to exhibit high activity in the methanation of CO and CO 2 [3,5,13,14]. Many literature reports give information about the influence of different factors on the activity of oxide-supported Ru systems [1,6,7,12,13,16,17]. However, there are few papers dealing with the activity of ruthenium deposited on thermally modified carbons [18,19]. There is also lack of information concerning the effect of Ru crystallite sizes on the activity of Ru/C systems. In the present work we made an effort to examine the influence of the ruthenium particle size in the wide range of its dispersion on the catalytic activity of Ru/graphitized carbon systems in CO methanation. The activity tests were conducted in H 2 -rich streams with very low CO concentrations (0.5 vol% CO) to simulate industrial conditions of hydrogen cleaning for NH 3 synthesis or fuel cells application. AbstractThe influence of the ruthenium crystallite size on the catalytic activity of Ru/graphitized carbon systems in carbon monoxide methanation was evaluated. Four graphitized carbon materials differing in their surface area were used as supports for Ru. The average size of Ru crystallites in Ru/C materials was estimated by X-ray powder diffraction, transmission electron microscopy and CO chemisorption. Dispersion of the active phase clearly depends on the carbon texture. The activity tests conducted in H 2 -rich streams with very low CO concentrations (0.5 vol% CO) have shown that the activity of Ru/carbon catalysts changes with the ruthenium particles size (d). The highest activities were obtained for ruthenium particles in the range 4-8 nm in size.

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Section: Catalyst Characterizationmentioning

confidence: 85%

The Effect of the Ruthenium Crystallite Size on the Activity of Ru/Carbon Systems in CO Methanation

et al. 2017

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“…Some say that it is a structural promoter [5,11,12], whereas others claim it is an electron promoter [36][37][38]. Moreover, there are papers which report a double role played by barium [39,40], i.e., both structural and electron. This opinion, however, is found mostly in papers which concern barium-ruthenium-support systems.…”

Section: Resultsmentioning

confidence: 99%

Cobalt Catalyst Doped with Cerium and Barium Obtained by Co-Precipitation Method for Ammonia Synthesis Process

et al. 2011

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Unsupported cobalt catalysts promoted with barium (symbol Co/Ba), cerium (Co/Ce) or both (Co/Ce/ Ba) were synthesized and tested in ammonia synthesis at 6.3 MPa. The Ba-free Co and Co/Ce oxide forms of the catalysts were prepared by precipitation/co-precipitation and a subsequent calcination at 500°C. The Co and Co/Ce powders were impregnated with an aqueous solution of barium nitrite. Nitrogen physisorption and H 2 chemisorption measurements revealed that cerium and barium play the role of structural promoters, which hinder the sintering of cobalt oxide during calcination and stabilize the surface of cobalt under reduction conditions. It seems that barium also modifies the surface of the active phase, i.e., cobalt. The kinetic studies of NH 3 synthesis have shown that the co-promoted material (Co/Ce/Ba) is about 2-3 times more active than the system doped with barium (Co/Ba) and more than ten times as active as that with Ce. At 400°C and at low conversion (1% NH 3 ), the ammonia synthesis rate (TOF) over Co/Ce/Ba proved to be almost 60% as high as that obtained for the commercial iron catalyst (KMI, H. Topsøe) commonly used in ammonia plants all over the world. Moreover, at the same temperature and a high ammonia concentration (8%) the co-promoted cobalt catalyst is over two times more active than the fused iron catalyst. Another asset of the cobalt catalyst is its high thermal stability.

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“…The formation BaCO 3 could be attributed to the reaction of BaO formed by barium nitrate decomposition and/or after the reduction process with CO 2 . The decomposition of barium nitrate begins at about 120 C and terminates at a relatively high temperature (approximately 420 C) [30]. Carbon dioxide can be produced according to the reaction: 2H 2 O þ C ¼ CO 2 þ 2H 2 .…”

Section: Xrd Resultsmentioning

confidence: 99%

“…CO 2 and H 2 O could also form during the reduction of oxygen containing functional groups which were present on the surface of the support. According to thermodynamic data, two consecutive steps could occur for the precursor of promoter: Ba(NO 3 ) 2 can be reduced to Ba 0 (Ba(NO 3 [30] or to BaO (Ba(NO 3 [10]. However, there were no signals corresponding to these phases, which could be due to their amorphous nature.…”

Section: Xrd Resultsmentioning

confidence: 99%

“…However, there were no signals corresponding to these phases, which could be due to their amorphous nature. BaO would easily react with CO 2 (BaO þ CO 2 ¼ BaCO 3 , DG ¼ À216.7 kJ [30]) to form the stable state of barium species in air, so BaO signals were not visible in the XRD pattern. Potassium chloride could form via the reaction of residual chlorine with KOH appeared in XRD patterns.…”

Section: Xrd Resultsmentioning

confidence: 99%

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Influence of chemical treatments of activated carbon support on the performance and deactivation behavior of promoted Ru catalyst in ammonia synthesis

Jafari

Saadatjou

Sahebdelfar³

2015

International Journal of Hydrogen Energy

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Barium-promoted Ru/carbon catalyst for ammonia synthesis: State of the system when operating

Cited by 61 publications

References 49 publications

The Effect of the Ruthenium Crystallite Size on the Activity of Ru/Carbon Systems in CO Methanation

The Effect of the Ruthenium Crystallite Size on the Activity of Ru/Carbon Systems in CO Methanation

Cobalt Catalyst Doped with Cerium and Barium Obtained by Co-Precipitation Method for Ammonia Synthesis Process

Influence of chemical treatments of activated carbon support on the performance and deactivation behavior of promoted Ru catalyst in ammonia synthesis

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