Ru-M catalyst

The crystal structure of pure Pt is face-centered cubic (fee), while that of Ru is hexagonal close packed (hep). For Ru atomic fractions up to about 0.7, Pt and Ru form a solid solution with Ru atoms replacing Pt atoms on the lattice points of the fee structure. The lattice constant decreases from 0.3923 (pure Pt) to 0.383 nm (0.675 atomic fraction of Ru). In contrast to bulk Pt-Ru alloys, it has to be remarked that in carbon supported catalysts the amount of Ru alloyed with Pt is lower than the nominal Ru content in the material the amount of Ru alloyed with Pt depends on the preparation method of the supported catalyst. In Pt-Ru-M catalysts, the third metal is an oxophilic element as W, Mo, Os, Ni, Ir, etc. Some of these elements can be fully alloyed, while several form alloys to a limited extent or not at all with Pl ... 

On a basis of trial and error it was noticed that a practical fuel cell attains higher performance employing ternary platinum based materials than employing the binary catalysts. During the last decade, the global observation reveals an increasing of performance for the H2/CO oxidation as well as for the MOR when a third element was added to the best bimetallic catalyst, the Pt-Ru [57] or Pt-Sn [58] based material. An overview of the preparation and structural characteristics of Pt-based ternary catalysts [59] and their electrochemical performance [60] was presented by AntoUni. Therein, all the relevant works before 2007 are found. In summary, many ternary Pt-Ru-M catalysts (M = Wi Wox or W2C form. Mo, Ir, Ni, Co, Rh, Os, V) perform better than commercial standard Pt-Ru catalysts and/or Pt-Ru catalysts prepared by the same method than the ternary. 

Fig. 6.7 Relationship between the ammonia conversion on Ru/M catalysts (667K) and electronegativity of the metal oxide (M)...

All of the supported bimetallic catalysts studied show a sharp drop in methanatlon activity when the Ru/M ratio falls below four. 

For a thorough review of Ru-NHC-catalysts for metathesis, see Samojlowicz C, Bieniek M, Grela K (2009) Chem Rev 109 3708-3742 for ruthenium indenylidene-complexes in cross metathesis, see Boeda F, Bantreil X, Clavier H, Nolan SP (2008) Adv Synth Catal 350 2959-2966 For Hll-types systems, see Schrodi Y, Pederson RL (2007) Aldrichimica Acta 40 45-52... 

Figure 7. Cyclic voltammetry polarization curves for MEA made with different Pt-Ru/C catalysts [25], 3M (Pt/Ru = 1 1), 3M (Pt/ Ru = 1 2) and 3 M (Pt/Ru = 2 1) represent the catalysts prepared using the unprotected metal nanoclusters as building blocks E-tek (Pt/ Ru = 1 1) represents the commercially available catalyst (C14-30). All the catalysts have the same total metal loading of 30wt.%.

Blume R, Havecker M, Zafeiratos S, Teschner D, Kleimenov E, Knop-Gericke A, Schlogl R, Barinov A, Dudin P, Kiskinova M. 2006. Catalytically active states of Ru(OOOl) catalyst in CO oxidation reaction. J Catal 239 354. 

Nurunnabi, M., Murata, K., Okabe, K., Inaba, M., and Takahara, I. 2007. Effect of Mn addition on activity and resistance to catalyst deactivation for Fischer-Tropsch synthesis over Ru/A1203 and Ru/Si02 catalysts. Catal. Commun. 8 1531-37. 

Similar intramolecular hydroarylations of alkynes and alkenes, which obviate the need for a halide or triflate group on the aryl ring, are now well established. Sames group screened over 60 potential catalysts and over 200 reaction conditions, and found that Ru(m) complexes and a silver salt were optimal. This process appears to tolerate steric hindrance and halogen substrates on the arene (Equations (175)—(177)). The reaction is thought to involve alkene-Ru coordination and an electrophilic pathway rather than a formal C-H activation of the arene followed by alkene hydrometallation, and advocates the necessary cautious approach to labeling this reaction as a C-H functionalization... 

A survey of Wacker-type etherification reactions reveals many reports on the formation of five- and six-membered oxacycles using various internal oxygen nucleophiles. For example, phenols401,402 and aliphatic alcohols401,403-406 have been shown to be competent nucleophiles in Pd-catalyzed 6- TZ /fl-cyclization reactions that afford chromenes (Equation (109)) and dihydropyranones (Equation (110)). Also effective is the carbonyl oxygen or enol of a 1,3-diketone (Equation (111)).407 In this case, the initially formed exo-alkene is isomerized to a furan product. A similar 5-m -cyclization has been reported using an Ru(n) catalyst derived in situ from the oxidative addition of Ru3(CO)i2... 

G. Lafaye, C. T. Williams, and M. D. Amiridis, Synthesis and microscopic characterization of dendrimer-derived Ru/A1203 catalysts, Catal. Lett. 96, 43-47 (2004). 

Carbon-supported platinum (Pt) and platinum-rathenium (Pt-Ru) alloy are one of the most popular electrocatalysts in polymer electrolyte fuel cells (PEFC). Pt supported on electrically conducting carbons, preferably carbon black, is being increasingly used as an electrocatalyst in fuel cell applications (Parker et al., 2004). Carbon-supported Pt could be prepared at loadings as high as 70 wt.% without a noticeable increase of particle size. Unsupported and carbon-supported nanoparticle Pt-Ru, ,t m catalysts prepared using the surface reductive deposition... 

Ito, E., Yamashita, M., Saito, Y. 1991. Acomposite Ru-Pt catalyst for 2-propanol dehydrogenation adaptable to the chemical heat pump system. Chem Soc Jpn Chem Lett 1 351-354. 

Figure 3.5 Cyclic voltammograms of Pt-Ru 60wt% catalysts supported on H-CNF, nanotunneled H-CNF and E-TEK catalyst 1 M MeOH + 1 M H2SO4 at 25 °C.

The homologation reaction was first reported nearly 40 years ago (2). The catalyst precursor was Co (CO). Subsequent workers utilized cobalt catalysts but also employed iodide promoters (, 4 ), a Ru co-catalyst ( ), and trivalent phosphines ( ) to increase the yield. The reaction is carried out at 180-200 °C and 4000-8000 psig. In the better cases, the ethanol rate and selectivity are 1-6 M/hr and 50-80 %. Unsatisfactory conversion, selectivity, and the required high operating pressure have prevented commercialization of the current homologation technology. Additionally, fermentation routes to ethanol have now... 

Figure 5.29. In situ polymerization in wet-ETEM (a) Co-Ru/titania catalyst (m) in HMD and adipic acid liquids on support grid (G) (b) in situ polymerization to polyamide (p) at 188 °C.

The diop system is the most effective of the Ru(II) chiral phosphine complexes that we have found for asymmetric hydrogenation (25, 26). The hydrogenation rates are about V50 as large as those using HRuCl(PPh3)3 under corresponding conditions (32) but are reasonably efficient nevertheless. For example, 1M solutions of atropic acid are converted quantitatively to 2-phen-ylpropionic acid (40% enantiomeric excess (ee)) in one day with 10 2 M catalyst at 1 atm H2. 

Figure 27. CO coverage at Pt (a) and Pt/Ru (b) catalyst as a function of the electrode potential in the presence (— —) and in the absence (- -o- -) of methanol in the solution. Methanol was adsorbed from 10 M CH3OH solution in the supporting electrolyte. Platinum loading was 0.8 mgcm. ...

Figure 2. Adamantane Hydroxylation Catalyzed by Ru"(TPFPP)(CO) and Ru (TPFPP)(0)2, [adamantane] = [pyCl2NO] = 0.02 M, [catalyst] = 50 pM, CH2CI2,4(PC. TO = moles of product/moles of catalyst...

Ru supported catalysts have been obtained by deposition of Ru on molecular sieves (L, APO-34, ZSM-5) in the potassium form from a solution containing 0.4 M RuCl, (Fluka purity)... 

On a pure Pt electrode, H20ads(Pt) dissociation is difficult [6,7] and relatively high positive electrode potentials are needed to activate H2O. Nanoscale binary Pt-M catalysts are often employed to increase the efficiency of CO electro-oxidation to combine the catalytic effects of both metals. The binary catalysts may be alloys or segregated metal particles. Pt-Ru and Pt-Sn alloys have received considerable attention as promising catalysts for the direct electro-oxidation of methanol (EOM) it has been shown that the catalytic activity of Pt for EOM can be enhanced by alloying with Ru or Sn. Other metals, e.g. Mo [17-21], Re [22], and Rh [23], have also been used as allo5dng metals. 

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