Carbon on ruthenium

Catalytic hydrogenation is mostly used to convert C—C triple bonds into C C double bonds and alkenes into alkanes or to replace allylic or benzylic hetero atoms by hydrogen (H. Kropf, 1980). Simple theory postulates cis- or syn-addition of hydrogen to the C—C triple or double bond with heterogeneous (R. L. Augustine, 1965, 1968, 1976 P. N. Rylander, 1979) and homogeneous (A. J. Birch, 1976) catalysts. Sulfur functions can be removed with reducing metals, e. g. with Raney nickel (G. R. Pettit, 1962 A). Heteroaromatic systems may be reduced with the aid of ruthenium on carbon. 

Ruthenium dioxide or ruthenium-on-carbon are effective catalysts for hydrogenation of mono- and dicarboxylic acids to the alcohol or glycol. High pressures (5,000-10,000 psig) and elevated temperatures (130-225 C) have been used in these hydrogenations 8,12,24). Yields of alcohol tend to be less than perfect because of esterification of the alcohol. Near quantitative yields of alcohol can be obtained by mixing ruthenium and copper chromite catalysts so as to reduce the ester as formed. 

More recently Hartog and Zwietering (103) used a bromometric technique to measure the small concentrations of olefins formed in the hydrogenation of aromatic hydrocarbons on several catalysts in the liquid phase. The maximum concentration of olefin is a function of both the catalyst and the substrate for example, at 25° o-xylene yields 0.04, 1.4, and 3.4 mole % of 1,2-dimethylcyclohexene on Raney nickel, 5% rhodium on carbon, and 5% ruthenium on carbon, respectively, and benzene yields 0.2 mole % of cyclohexene on ruthenium black. Although the cyclohexene derivatives could not be detected by this method in reactions catalyzed by platinum or palladium, a sensitive gas chromatographic technique permitted Siegel et al. (104) to observe 1,4-dimethyl-cyclohexene (0.002 mole %) from p-xylene and the same concentrations of 1,3- and 2,4-dimethylcyclohexene from wi-xylene in reductions catalyzed by reduced platinum oxide. 

Catalyst deactivation often plays a central role in manufacturing of various alimentary products. Sugar alcohols, such as xylitol, sorbitol and lactitol, are industrially most commonly prepared by catalytic hydrogenation of corresponding sugar aldehydes over sponge nickel and ruthenium on carbon catalysts (5-10). However, catalyst deactivation may be severe under non-optimized process conditions. 

An autoclave was charged with the step 2 product mixture (91.0 g), 5 wt% ruthenium on carbon (9.1 g), and 300 ml diisopropyl ether and then sealed and heated to 100°C. Hydrogen was then introduced and the reaction continued for 14 hours at 0.7-1.0 mPa. The mixture was then filtered by Celite , concentrated, and 82.7 g of product isolated as white crystals after recrystallization. Analysis of the mixture indicated it consisted of four isomers (Isomers 1-4) in an isomeric ratio of Isomer 1 (preferred) Isomer 2 Isomer 3 Isomer 4 of 37 36 17 10, respectively. 

Chemically pure monosaccharides and disaccharides were used. The catalyst (5% Ruthenium on carbon) was purchased from ALDRICH. 

Under hydrogenation conditions further unexpected chemistry occurs. The results of two hydrogenations are shown in Fig. 3. Both were run using 0.22 M substrate in water. The catalyst was a 5% ruthenium on carbon support, and the reaction was carried out at 150°C at 13.7 MPa of hydrogen. In one case, 0.29 M phosphoric acid was added, and in the other no additional acid was used. 

The solution of 5.0 g of l-(4-pyridyl)-2-imidazolidinone in 45 ml of water is hydrogenated over 0.8 g of 10% ruthenium on carbon at 120°C and 120 atm until the hydrogen absorption ceases. It is filtered, the filtrate evaporated, the residue taken up in chloroform, the solution dried, evaporated to yield the 1-(4-piperidyl)-2-imidazolidinone, melting point 155°-157°C (recrystallized from methylene chloride-petroleum ether). 

This thesis was demonstrated (1) in the selective hydrogenation of the pairs of olefins shown in Table I, over ruthenium-on-carbon, a catalyst with relatively low isomerization activity. The experiments were carried out by partial hydrogenation of a mixture of 1 mole of each olefin, and the reaction was interrupted and analyzed after absorption of 1 mole of hydrogen. Those compounds underlined in Table I were reduced with high selectivity in preference to the other member of the pair. This high degree of selectivity was limited to those pairs of olefins... 

Table I. Competitive Hydrogenation of Olefins by Ruthenium on Carbon...

Rylander and Rakoncza compared the rates of hydrogenation of pyridine V-oxide over 5% palladium-, platinum-, rhodium-, and ruthenium-on-carbon in methanol, water, and acetic acid.224 Rhodium was always the most active, although the pyridine ring was hydrogenated concomitantly with the reduction of the V-oxide group. 

Ruthenium-on-carbon achieves the selective saturation of the highly functionalized enol lactone, 14, in methanoP ... 

Ruthenium-on-carbon and ruthenium-on-alumina also are effective for reduction of a phenolic ring in polycyclic compounds. Anilines are hydrogenated under the same con-... 

Ruthenium-on-carbon in aqueous ethanol or platinum oxide also is used but to a much lesser extent than Pd. Palladium shows a low activity for hydrogenation of nonactivated aliphatic ketones, but all the platinum metals can be used in addition to Cu chromite and Ni catalysts. Platinum catalysts have been widely used, platinum-on-carbon in aqueous acid is satisfactory. Rhodium is active under mild conditions and leads to a-hydroxy steroids in excellent yields ... 

Selective hydrogenation of the nitro function in aromatic nitro ketones, esters, and amides takes place over various catalysts such as Pd black in H2SO4, palladium-on-carbon, platinum oxide, and even ruthenium-on-carbon the nitro function is preferentially adsorbed. For preparation of an intermediate required in the synthesis of... 

Wildschut J, Iqbal M, Mahfud FH, Cabrera IM, Venderbosch RH, Heeres HI (2010) Insights in the hydrotreatment of fast pyrolysis oil using a ruthenium on carbon catalyst. Energ Environ Sci 3(7) 962-970... 

Heterogeneous catalysts such as Ru-Al-Mg-hydrotaldte, Ru-Co-Al-hydrotalcite, Ru-hydroxyapatite (RuHAP) (Eq. (7.40)) [91], RU-AI2O3 [92a,b], and Ru/A10(OH) [92c] are highly efficient catalysts for aerobic oxidation of alcohols. In these oxidation reactions, the key step is postulated as the reaction of Ru-H with O2 to form Ru-OO H, in analogy to Pd-OOH, which has been shown to operate in the palladium-catalyzed Wacker-type asymmetric oxidation reaction [93]. It is noteworthy that ruthenium on carbon is simple and efficient for the oxidation of alcohols (Eq. (7.41)) [92d]. 

As early as the middle of 1960s, BP successfully developed a kind of oleophylic graphite with excellent adsorption ability, and then a kind of graphited carbon in 1974, which could be used as supports for various catalysts. From 1978 to 1984, BP claimed a series of patents on ruthenium catalysts for ammonia synthesis. In 1979, ° a novel catalyst for ammonia synthesis was prepared by loading carbonyl compound of ruthenium on carbon containing graphite in laboratory. This kind of catalyst, with graphited carbon as support and Rus (CO) 12 as the precursor, possessed some special features that may be summarized as follows ... 

Hvdroeeri, Ruthenium on Carbon 1335-7A-0/74AO-18-8 7 7 7,2 Flammable Relative cost cheao. Catalvit can be recvded. 

Figure 9.1. Comparison of the performance characteristics of alkali-promoted ruthenium on carbon and triple promoted magnetite a. Pressure and H/N ratio response (data at 6vol% ammonia, 673 K) b. Ammonia inhibition (data at 13,790 kPa, 703 K).

This rate expression provides an excellent description of the operating characteristics of alkali-promoted ruthenium on carbon catalysts over a wide range of pressure, temperature, and gas composition based on kinetic constants derived directly from pilot plant studies. 

As an exception that proves the rule, the KAAP (KBR Advanced Ammonia Process) ruthenium-on-carbon catalyst was introduced to commercial application with a Canadian plant retrofit in 1992. The manufacturer claims that the activity of the catalyst exceeds that of magnetite-based materials by about an order of magnitude. 

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