Carbon monoxide on rhodium

Leung, L.-W.H. and Weaver, M.J. (1988) Adsorption and electrooxidation of carbon monoxide on rhodium- and ruthenium-coated gold electrodes as probed by surface-enhanced... 

TABLE 4.3. Selected Vibrational Frequencies for Carbon Monoxide on Rhodium"... 

G-19 Dicarboxylic Acids. The C-19 dicarboxyhc acids are generally mixtures of isomers formed by the reaction of carbon monoxide on oleic acid. Since the reaction produces a mixture of isomers, no single chemical name can be used to describe them. Names that have been used include 2-nonyldecanedioic acid, 2-octylundecanedioic acid, l,8-(9)-heptadecanedicarboxyhc acid, and 9-(10)-carboxystearic acid. The name 9-(10)-carboxystearic acid can be used correctiy if the product is made with no double bond isomerization (rhodium triphenylphosphine catalyst system). 

Figure A.16 Energy diagram for the adsorption of carbon monoxide on the (100) plane of rhodium (from de Koster et al. [21]).

In the presence of carbon monoxide this rhodium catalyst has no activity for hydrogenation and the selectivity based on starting material is virtually 100%. The butanal produced contains no alcohol and can be converted both to butanol and to other products as desired. 

Propene hydroformylation can lead to products with a linearity ranging from 60 to 95%, depending on the phosphine concentration. At very high phosphine concentration the rate is low, but the linearity achieves its maximum value. Low ligand concentrations, with concomitant low linearities, will give turnover frequencies in the order of 10,000 mol mol-1 h 1 at 10 bar and 90°C. In the presence of carbon monoxide this rhodium catalyst has no activity for hydrogenation and the selectivity, based on starting material, is virtually 100%. The butanal produced contains no alcohol and can be converted both to butanol and to other products, as desired. 

Al-Ammar AS, Webb G (1978) Hydrogenation of acetylene over supported metal catalysts Part 1 - Adsorption of [ C] Acetylene and [ C] ethylene on silica supported rhodium, iridium and palladium and alumina supported palladium. J Chem Soc Earaday Trans 74 195 Al-Ammar AS, Webb G (1979) Hydrogenation of acetylene over supported metal catalysts Part 3 - [ C] tracer studies of the effect of added ethylene and carbon monoxide on the reaction catalyzed by silica-supported palladium, rhodium and iridium. J Chem Soc Faraday Trans 75 1900... 

Galwey AK, Bettany DG, Mortimer M (2006) Kinetic compensation effects observed during oxidation of carbon monoxide on y-alumina supported palladium, platinum, and rhodium metal catalysts toward a mechanistic explanation. Int J Chem Kin 38 689... 

The influence of the support is undoubted and spillover was further confirmed by the excess of hydrogen chemisorbed by a mechanical mixture of unsupported alloy and TJ-A1203 above that calculated from the known values for the separate components. It was also observed that the chemisorption was slower on the supported than on the unsupported metal and that the greater part of the adsorbate was held reversibly no comment could be made on the possible mediation by traces of water. On the other hand, spillover from platinum-rhenium onto alumina appears to be inhibited for ratios Re/(Pt Re) > 0.6. In an infrared investigation of isocyanate complexes formed between nitric oxide and carbon monoxide, on the surface of rhodium-titania and rhodium-silica catalysts, it seems that the number of complexes exceeded the number of rhodium surface atoms.The supports have a pronounced effect on the location of the isocyanate bond and on the stability of the complexes, with some suggestion of spillover. 

M.A. Van Hove, R.F. Lin, and G.A. Somorjai. Surface Structure Determination of Coadsorbed Benzene and Carbon Monoxide on the Rhodium (111) Single Crystal Surface Analyzed with Low-Energy Electron Diffraction Intensities. J. Am. Chem. Soc. 108 2532 (1986). 

Figure 6.23. Increase of rhodium work function upon chemisorption of carbon monoxide on the (111) surface [40].

It is known that strong acids act as oxidants. Consequently, acidic surface hydroxyls can also be oxidizers. This reaction potential of surface OH groups is well expressed when they interact with supported metals. For example, it was reported that adsorption of carbon monoxide on dispersed supported metaUic rhodium leads to formation of geminal dicarbonyls of Rh (163). 

The HPLP apparatus has been used to study the hydrogenation of carbon monoxide on iron and rhodium polycrystalline specimens as well as on sit e crystals and various rhodium compounds." Postreaction surface analysis revealed the presence of a catalytically active carbonaceous layer on all the samples investigated. In addition, precise control of the rhodium surface oxidation state by oxygen pretreatment in the UHV chamber was found to have a marked effect on the product distribution of the rhodium catalyzed reaction. 

Weaver MJ, Chang SC, Leung LWH, Jiang X, Rubel M, Szklarczyk M, et al. Evaluation of absolute saturation coverages of carbon monoxide on ordered low-index platinum and rhodium electrodes. J Electroanal Chem 1992 327 247-60. 

Patterson, M., Angove, D. and Cant, N. (2000). The effect of carbon monoxide on the oxidation of four Cg to Cg hydrocarbons over platinum, palladium and rhodium, Appl. Catal. B Environmental, 26, pp. 47-57. 

The unit has virtually the same flow sheet (see Fig. 2) as that of methanol carbonylation to acetic acid (qv). Any water present in the methyl acetate feed is destroyed by recycle anhydride. Water impairs the catalyst. Carbonylation occurs in a sparged reactor, fitted with baffles to diminish entrainment of the catalyst-rich Hquid. Carbon monoxide is introduced at about 15—18 MPa from centrifugal, multistage compressors. Gaseous dimethyl ether from the reactor is recycled with the CO and occasional injections of methyl iodide and methyl acetate may be introduced. Near the end of the life of a catalyst charge, additional rhodium chloride, with or without a ligand, can be put into the system to increase anhydride production based on net noble metal introduced. The reaction is exothermic, thus no heat need be added and surplus heat can be recovered as low pressure steam. 

Patents on the catbonylation of methyl chlotide [74-87-3] using carbon monoxide [630-08-0] in the presence of rhodium, palladium, and tidium complexes, iodo compounds, and phosphonium iodides or phosphine oxides have been obtained (26). In one example the reaction was conducted for 35... 

Often the aldehyde is hydrogenated to the corresponding alcohol. In general, addition of carbon monoxide to a substrate is referred to as carbonylation, but when the substrate is an olefin it is also known as hydroformylation. The eady work on the 0x0 synthesis was done with cobalt hydrocarbonyl complexes, but in 1976 a low pressure rhodium-cataly2ed process was commerciali2ed that gave greater selectivity to linear aldehydes and fewer coproducts. 

Other Methods. A variety of other methods have been studied, including phenol hydroxylation by N2O with HZSM-5 as catalyst (69), selective access to resorcinol from 5-methyloxohexanoate in the presence of Pd/C (70), cyclotrimerization of carbon monoxide and ethylene to form hydroquinone in the presence of rhodium catalysts (71), the electrochemical oxidation of benzene to hydroquinone and -benzoquinone (72), the air oxidation of phenol to catechol in the presence of a stoichiometric CuCl and Cu(0) catalyst (73), and the isomerization of dihydroxybenzenes on HZSM-5 catalysts (74). 

In one patent (31), a filtered, heated mixture of air, methane, and ammonia ia a volume ratio of 5 1 1 was passed over a 90% platinum—10% rhodium gauze catalyst at 200 kPa (2 atm). The unreacted ammonia was absorbed from the off-gas ia a phosphate solution that was subsequently stripped and refined to 90% ammonia—10% water and recycled to the converter. The yield of hydrogen cyanide from ammonia was about 80%. On the basis of these data, the converter off-gas mol % composition can be estimated nitrogen, 49.9% water, 21.7% hydrogen, 13.5% hydrogen cyanide, 8.1% carbon monoxide, 3.7% carbon dioxide, 0.2% methane, 0.6% and ammonia, 2.3%. 

We have undertaken a series of experiments Involving thin film models of such powdered transition metal catalysts (13,14). In this paper we present a brief review of the results we have obtained to date Involving platinum and rhodium deposited on thin films of tltanla, the latter prepared by oxidation of a tltanliua single crystal. These systems are prepared and characterized under well-controlled conditions. We have used thermal desorption spectroscopy (TDS), Auger electron spectroscopy (AES) and static secondary Ion mass spectrometry (SSIMS). Our results Illustrate the power of SSIMS In understanding the processes that take place during thermal treatment of these thin films. Thermal desorption spectroscopy Is used to characterize the adsorption and desorption of small molecules, In particular, carbon monoxide. AES confirms the SSIMS results and was used to verify the surface cleanliness of the films as they were prepared. 

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