Activated carbon supported ruthenium catalysts

The addition of MgO to activated carbon-supported ruthenium catalysts in an optimal Ru Mg ratio results in efficient catalyts for the CO2 reforming of methane, with stable selectivities towards CO and H2 production. 

Activated carbon supported ruthenium catalysts for ammonia synthesis... 

H2 reduction method. The elimination of chlorines in catalyst is an important role and step during the preparation of ruthenium catalyst. In order to eliminate the Cl in activated carbon supported ruthenium catalyst prepared using RuClg as the precursors, it is necessary that RuCla is reduced to elementary ruthenium and... 

Therefore, one key subject for activated carbon supported ruthenium catalyst study is to solve the loss of activated carbon due to methanation and many scientists have done a lot of studiesd d7,39,iio,i2i,220 current solutions way includes (i) Graphitization of activated carbon and using promoter can inhibit the methanation (ii) Seek for new support that can replace the activated carbon such as metal oxide. 

One of the important reasons of activated carbon supported ruthenium catalyst, which has not been widely applied, is the loss of activated carbon as support due to methanation. Therefore, it has theoretical and practical significance to study the reaction mechanism of activated carbon methanation and inhibition of methanation for ruthenium catalysts. 

Palladium gave the highest activity of all the platinum group metals evaluated platinum, rhodium and ruthenium exhibited very poor activity. The choice of support was also demonstrated to be very important the activated carbon supported Pd catalyst showed a nearly fourfold increase in activity than did Pd supported on alumina. 

Nie J, Xie J, Liu H (2013) Activated carbon-supported ruthenium as an efficient catalyst for selective aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran. Chinese J Catal 34 871-875... 

Another reason of the surface enrichments or loss is the formation of volatile compounds of a certain component of catalysts with reactants. For example, nickel can react with carbon monoxide in reactants to form the volatile and thermally unstable nickel carbonyl, which escapes gradually from the catalyst surface. The activated carbon supported ruthenium-based catalysts also loses obviously part of itself due to the volatilization of ruthenium oxides or the occurrence of methanation reactions of the activated carbon. 

In summary, the determination of surface functional groups on the activated carbons and the catalytic properties are rather complicated. It is one of the key and difficult points for studying the catalysts supported on the activated carbons. ° The influences of sm-face chemical property of activated carbons on ruthenium catalysts are very complicated and uncertain, which should be further investigated. 

It was seen when studying mixed systems Pt-WOj/C and Pt-Ti02/C that with increasing percentage of oxide in the substrate mix the working surface area of the platinum crystallites increases, and the catalytic activity for methanol oxidation increases accordingly. With a support of molybdenum oxide on carbon black, the activity of supported platinum catalyst for methanol oxidation comes close to that of the mixed platinum-ruthenium catalyst. 

Homogeneous deposition precipitation (HDP) is explored for the preparation of carbon nanofiber supported ruthenium catalysts. First, carbon nanofibers (CNF, 177 m /g) are oxidized using nitric acid thus activating the graphitic carbon surfiice. Second, ruthenium (hydr)oxide is deposited homogeneously onto the CNF by hydrolysis of urea at 363K. 

In a more recent study, Li et al. [15] investigated the catalytic behavior of ruthenium catalysts supported on carbon materials with different porous and graphitic structures in the catalytic ammonia decomposition. They found that the catalytic activity followed the trend Ru/GC (graphitic carbon)> Ru/CNTs (carbon nantoubes) > Ru/CB-S (carbon black) > Ru/CB-C > Ru/CMK-3 (meso-porous carbon) = Ru/AC. It was concluded that the graphitic structure of the carbons was critical to the activity of the ruthenium catalysts, whereas the surface area and porosity were less important. 

It has been claimed that carbon-supported ruthenium-based catalysts for ammonia synthesis show some important drawbacks, such as high catalyst cost and methanation of the carbon snpport under industrial reaction conditions. This has stimnlated the research for alternative catalysts, although the use of carbon snpports is a common feature. One example of these new catalysts is provided by the work of Hagen et al. [61], who reported very high levels of activity with barinm-promoted cobalt catalysts snpported on Vulcan XC-72. It was demonstrated that althongh cobalt had received little attention as a catalyst for ammonia synthesis, promotion with barium and the nse of a carbon support resulted in very active catalysts with very low NH3 inhibition. 

J. Assmann, V. Narkhede, L. Khodeir, E. Loffler, O. Hinrichsen, A. Birkner, H. Over, and M. Muhler, On the nature of the active state of supported ruthenium catalysts used for the oxidation of carbon monoxide Steady state and transient kinetics combined with in situ infrared spectroscopy, J. Phys. Chem. B 108, 14634 (2004). 

P., Fiechter, S., Bron, M., and Tributsch, H. (2006) Oxygen reduction at carbon supported ruthenium-sdenium catalysts selenium as promoter and stabilizer of catalytic activity. J. Power Sources, 155 (1), 47-51. 

The addition of other metals to the heterogeneously cobalt-catalyzed reaction can have a beneficial effect on hydroformylation. For example, small amounts of ruthenium added to a carbon-supported cobalt catalyst (Co/AC) increased activity as well as Hb selectivity [64]. The effect was rationalized by the high dispersion and reducibUity of supported cobalt. When ruthenium was added, small particles of an unbalanced alloy were formed. These particles keep more CO in a nondisso-ciative state and lower the surface hydrogen pressure. This was in contrast to the related but uniformly distributed Pt-Co or Pd-Co alloys. Activity and regioselectivity increased with increased Ru loading. 

Rapoport s findings have been confirmed in the authors laboratory where the actions of carbon-supported catalysts (5% metal) derived from ruthenium, rhodium, palladium, osmium, iridium, and platinum, on pyridine, have been examined. At atmospheric pressure, at the boiling point of pyridine, and at a pyridine-to-catalyst ratio of 8 1, only palladium was active in bringing about the formation of 2,2 -bipyridine. It w as also found that different preparations of palladium-on-carbon varied widely in efficiency (yield 0.05-0.39 gm of 2,2 -bipyridine per gram of catalyst), but the factors responsible for this variation are not knowm. Palladium-on-alumina was found to be inferior to the carbon-supported preparations and gave only traces of bipyridine,... 

Recently, rhodium and ruthenium-based carbon-supported sulfide electrocatalysts were synthesized by different established methods and evaluated as ODP cathodic catalysts in a chlorine-saturated hydrochloric acid environment with respect to both economic and industrial considerations [46]. In particular, patented E-TEK methods as well as a non-aqueous method were used to produce binary RhjcSy and Ru Sy in addition, some of the more popular Mo, Co, Rh, and Redoped RuxSy catalysts for acid electrolyte fuel cell ORR applications were also prepared. The roles of both crystallinity and morphology of the electrocatalysts were investigated. Their activity for ORR was compared to state-of-the-art Pt/C and Rh/C systems. The Rh Sy/C, CojcRuyS /C, and Ru Sy/C materials synthesized by the E-TEK methods exhibited appreciable stability and activity for ORR under these conditions. The Ru-based materials showed good depolarizing behavior. Considering that ruthenium is about seven times less expensive than rhodium, these Ru-based electrocatalysts may prove to be a viable low-cost alternative to Rh Sy systems for the ODC HCl electrolysis industry. 

Carbon-supported Ru-Sn catalyst Ru and Sn Mossbauer measurements were performed to investigate catalysts of ruthenium and tin supported on activated carbon (Ru-Sn/C). The samples were subjected to different reducing and oxidizing treatments. The presence of tin leads to a substantial increase of the Lamb-Mossbauer factor of the metallic Ru-particles showing that tin strengthens the attachment of the particles to the support. The close contact between the two metals appears to be decisive for the formation of catalytically active sites (Ru-Sn and Ru-SnOj,-)... 

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