Carbon monoxide sweep

M REC, as the TREC, does not depend on the reaction path. In addition, there is no dependence on the membrane-permeation properties (related to the time required for species permeation).1 In any case, the final value reached depends on the extractive capacity of the system, for example, the pressure and composition on the permeate side. The composition on the permeate side, similarly to the feed molar ratio, can be expressed by considering the ratio (named sweep factor) between the initial molar number of nonpermeating species (present on the permeate side) and the initial molar number of the reference reactant, for example, methane for methane steam reforming, or carbon monoxide for water gas shift). The sweep factor was defined for a closed M Ras ... 

The reduction of [Fe3 ( 3-S)2 (CO)g (tSCHCHli) ] in DMF is reversible at fast cyclic voltammetric sweep rates ( = -0.73 V). In the presence of P(OMe)3, three new reduction waves are observed, revealing the stepwise substitution of carbonyl ligands to give [Fe3(/X3-S)2(CO)8 P(OMe)3 (< SCHCHS)] n = 1-3). Under 1 atm carbon monoxide, the rate of substitution was less, leading thd authors to favor a mechanism involving CO displacement after the initial reduction step, rather than rupture of the M—M bond before ligand loss. In either case, reduction clearly activates the cluster toward carbonyl substitution 150). 

The complexes can be both oxidized and reduced reduction potentials for many of the complexes are shown in Table 6. Cyclic voltammograms of Re(a-diimine)(CO)3X show that in most cases the first oxidation is chemically irreversible at scan rates of 0.1-0.2 V s however, at much faster sweep rates (>100 V s ) a reversible wave is observed at 1.32 V (vs. SCE) in MeCN for Re(bpy)(CO)3Cl [60]. The first oxidation is metal based and is followed by the rapid loss of carbon monoxide due to the weakening of the Re 7r-backbonding... 

FIGURE 6.2 Effect of reaction pressure on conversion of carbon monoxide. Reaction conditions catalyst (Girdler G-3), 3.0 g temperature, 400 °C H2O/CO ratio, 1 feed rate of carbon monoxide, 25 ml/min. Sweep argon flow rate, 400 ml/min pressure, 1 atm. (Taken from Figure 3 ofE. Kikuchi, S. Uemiya, N. Sato, H. Inoue, H. Ando, T. Masuda, Chem. Lett. (1989) 489.)... 

Vacuum technique may be used instead of sweeping, but in the absence of carbon monoxide the iron tetracarbonyl dihydride is much more likely to decompose in the wanner part of the apparatus. 

Kikuchi [111] described a natural gas MR, which had been developed and operated by Tokyo Gas and Mitsubishi Heavy Industries to supply PEM fuel cells with hydrogen. It was composed of a central burner surrounded by a catalyst bed filled with commercial nickel catalyst. Into the catalyst bed 24 supported palladium membrane tubes were inserted. The membranes had been prepared by electroless plating and were 20 pm thick. Steam was used as sweep gas for the permeate. The reactor carried 14.5 kg catalyst. It was operated at 6.2 bar pressure, S/C ratio of 2.4, and 550°C reaction temperature. The conversion of the natural gas was close to 100%, wdiile the equilibrium conversion was only 30% under the operating conditions. The retentate composition was 6 vol.% hydrogen, 1 vol.% carbon monoxide, 91 vol.% carbon dioxide, and 2 vol.% methane. 

Anodic Reactions in Electrocatalysis -Oxidation of Carbon Monoxide, Fig. 3 Cyclic voltammogram of a rotating polycrystalline Pt disk electrode in CO saturated 0.1 M H2SO4. Potential sweep rate 0.050 V s rotation rate 900 rpm. The inset shows the integrated IR peak of COj,j plotted versus the position on the electrode for the applied current of 0.3, 1.4, 1.5, 1.7, 1.75, and 1.8 mA left to right and top to bottom). The red color indicates a high CO j coverage and the blue a CO-free surface (Reproduced from Ref [28] with permission of the American Chemical Society)... 

Electrolytes were prepared with water of 18 cm conductivity purified by a Bamstead Nanopure system and doubly distilled perchloric acid (70 wt%, G. F. Smith Chemicals). Carbon monoxide was dosed from solution by a 1 min exposure of the sample to 0.1 mol/dm perchloric acid saturated with carbon monoxide at 1 atm while maintaining the potentid at 0.3 V. The carbon monoxide solution was then removed and the sample rinsed once with blank electrolyte prior to electrochemical measurements. Electrode potentials were measured with respect to a gold/gold oxide reference electrode and converted to the reversible hydrogen electrode (RHE) scale. All cyclic voltammograms were recorded at room temperature with a sweep rate of 50 mV/s. To avoid electrooxidation of the carbon adlayers the sample potential was not allowed to exceed 0.95 V. 

A carrier gas, such as nitrogen, helium, or a helium/ hydrogen mixture, sweeps the pyrolysis gases into any of four downstream systems of reactors, scrubbers, separators, and detectors for the determination of the carbon monoxide content, hence of the oxygen in the original fuel sample. The result is reported as mass % oxygen in the fuel. 

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