Activated carbon supported ruthenium

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. 

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... 

Activated carbon supported ruthenium catalysts for ammonia synthesis... 

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. 

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. 

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. 

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. 

However, ruthenium is a rare earth mineral that is highly toxic and its high cost prevents its market use. Due to the high cost of RUO2, deposition techniques must be optimized to deposit small quantities and enhance material utilization within a device. To further optimize use, composites with high-surface-area activated carbon supports can be used. Despite the strong performance characteristics of RUO2, inevitable supply and demand issues push the market toward other pseudocapacitive materials. 

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. 

The investigation of hydrogen adsorption of the activated carbon supported RuCla and carhonyl ruthenium (chlorine-free) indicates that the adsorption amount of the hydrogen of the sample containing chlorine is much larger than that of the chlorine-free sample (Table 6.24). 

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. 

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. 

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,-)... 

With regard to biosensor applications, a wide variety of electrochemically active species (ferrocene, ruthenium complexes, or carbon and metal (Pt, Pd, Au...) [185,186] were also introduced into the sol-gel matrices or adsorbed to improve the electron transfer from the biomolecules to the conductive support [187,188]. For instance, glucose oxidase has been trapped in organically modified sol-gel chitosan composite with adsorbed ferrocene to construct a low-cost biosensor exhibiting high sensitivity and good stability [189]. 

The feasibility of carbon-supported nickel-based catalysts as the alternative to the platinum catalyst is studied in this chapter. Carbon-supported nickel (Ni/C, 10 wt-metal% [12]), ruthenium (Ru/C, 10 wt-metal% [12]), and nickel-ruthenium composite (Ni-Ru/C, 10 wt-metal%, mixed molar ratio of Ni/Ru 0.25,1,4, 8, and 16 [12]) catalysts were prepared similarly by the impregnation method. Granular powders of the activated carbon without the base pretreatment were stirred with the NiCl2, RuC13, and NiCl2-RuCl3 aqueous solutions at room temperature for 24 h, respectively. Reduction and washing were carried out in the same way as done for the Pt/C catalyst. Finally, these nickel-based catalysts were evacuated at 70°C for 10 h. 

Ruthenium catalysts, supported on a commercial alumina (surface area 155 m have been prepared using two different precursors RUCI3 and Ru(acac)3 [172,173]. Ultrasound is used during the reduction step performed with hydrazine or formaldehyde at 70 °C. The ultrasonic power (30 W cm ) was chosen to minimise the destructive effects on the support (loss of morphological structure, change of phase). Palladium catalysts have been supported both on alumina and on active carbon [174,175]. Tab. 3.6 lists the dispersion data provided by hydrogen chemisorption measurements of a series of Pd catalysts supported on alumina. is the ratio between the surface atoms accessible to the chemisorbed probe gas (Hj) and the total number of catalytic atoms on the support. An increase in the dispersion value is observed in all the sonicated samples but the effect is more pronounced for low metal loading. 

Alumina-supported Ru catalysts derived from supported ruthenium carbonyls have been reported to be effective for carbon dioxide methanation, showing higher activity than other catalysts prepared from RUCI3. The catalytic activity depended on the nuclearity of the carbonyl precursor [111]. 

There is increased interest in the use of Ru-based systems as catalysts for oxygen reduction in acidic media, because these systems have potential applications in practicable direct methanol fuel cell systems. The thermolysis of Ru3(CO)i2 has been studied to tailor the preparation of such materials [123-125]. The decarbon-ylation of carbon-supported catalysts prepared from Ru3(CO)i2 and W(CO)6, Mo(CO)is or Rh(CO)is in the presence of selenium has allowed the preparation of catalysts with enhanced activity towards oxygen reduction, when compared with the monometallic ruthenium-based catalyst [126],... 

Carbonylation of Methyl Acetate on Ni/A.C. Catalysts. Table II shows the catalytic activities of nickel and platinum group metals supported on activated carbon for the carbonylation of methyl acetate. Ruthenium, palladium, or iridium catalysts showed much lower activity for the synthesis of acetic anhydride than the nickel catalyst. In contrast, the rhodium catalyst, which has been known to exhibit an excellent carbonylation activity in the homogeneous system (1-13), showed nearly the same activity as the nickel catalyst but gave a large amount of acetic acid. 

---