Carbon monoxide conversion

Synthesis gas preparation consists of three steps ( /) feedstock conversion, (2) carbon monoxide conversion, and (2) gas purification. Table 4 gives the main processes for each of the feedstocks (qv) used. In each case, except for water electrolysis, concommitant to the reactions shown, the water-gas shift reaction occurs. 

In run 19, where considerable carbon monoxide conversion was obtained in both stages, the recycle ratio was 1.48 scf recycle gas per scf feed gas. Recycle ratios in the other tests varied from 1.14 to 1.30. The design recycle ratio is 1.67 for lignite coal feed with hydrogen/steam synthesis gas. 

In all operations to date, carbon monoxide conversion has been... 

Before hydrogen addition to ensure complete carbon monoxide conversion. c Saturated at 30 in. mercury and 15.6° C nitrogen-free basis. d Total gas composition = 100.00%. 

To summarize the test results, the HYGAS methanation section has operated satisfactorily. Carbon monoxide conversion has been complete. The cold-gas recycle system was completely adequate for temperature... 

Fig. 18. Inhibition effect of carbon monoxide on carbon monoxide conversion at 400°F over platinum. 100 ppm CaH8> 4.5% 02, 100 ppm NO.

The catal5fsts were tested for CO oxidation in a flow reactor using a 2.5 % CO in dry air mixture at a fixed flow rate of 200 seem. Thirty milligrams of the catalyst were used for each experimental run. The reaction was conducted at 298, 323, 373 and 473 K with 75 minutes duration at each temperature. The carbon monoxide conversion to carbon dioxide was monitored by an online gas chromatogr h equipped with a CTR-1 column and a thermal conductivity... 

GP 9[ [R 16]The extent of internal transport limits was analysed for the wide fixed-bed reactor, using experimental data on carbon monoxide conversion and matter and process parameter data for the reactants [78]. The analysis was based on the Weisz modulus and the Anderson criterion for judging possible differences between observed and actual reaction rates. As a result, it was found that the small particles eliminate internal transport limitations. 

Sarup, B., and Wojciechowski, B.W. 1989. Studies of the Fischer-Tropsch synthesis on a cobalt catalyst. II. Kinetics of carbon monoxide conversion to methane and to higher hydrocarbons. Can. J. Chem. Eng. 67 62-74. 

The gases from the furnace are cooled by the addition of condensate and steam, and then passed through a converter containing a high or low temperature shift catalyst, depending on the degree of carbon monoxide conversion desired. Carbon dioxide and hydrogen are produced by the reaction of the carbon monoxide with steam. 

These indicate two different ways of carbon monoxide conversion both processes are highly exothermic. Iron catalyzes the transformation according to Eq. (3.8),... 

The stages of isotopic exchange mechanism (357), if we do not distinguish between isotopes H and D, coincide with the forward and reverse directions of stage 1 of mechanism (343) of carbon monoxide conversion. The reactions of isotopic exchange corresponding to stage 2 or this mechanism... 

On Fe304 the rates of isotopic exchange reactions (356), (366), and (367) are close to the rate of carbon monoxide conversion, as should be expected from mechanism (343). 

It is natural to assume on the basis of mechanism (379) of the reaction of carbon with carbon dioxide and the mechanism of carbon monoxide conversion, (343), that the reaction of carbon with steam occurs as follows ... 

Stage 1 of this mechanism is analogous to stage 1 of mechanism (379), stage 2 of both mechanisms are identical, and stage 3 coincides with stage 1 of mechanism (379) written in the reverse direction. On the other hand, stages 1 and 3 conform with the mechanism of carbon monoxide conversion (343). Such a mechanism of reaction (378) was proposed by Key (151). 

A 10 Ndm3 min-1 feed composed of 75.0% H2, 0.7% CO and balance C02 with air for oxidation was fed into the relatively large test reactor carrying 230 cm3 catalyst microsperes of 1 mm diameter. Of the non-precious metal catalysts, that composed of hopcalite showed the highest activity, achieving almost full conversion in the temperature range 130-160 °C. The minimum CO output achieved was 40 ppm. A minimum 02/CO ratio of 2.5 was determined for this catalyst to achieve a carbon monoxide conversion exceeding 90%. The catalysts tested are summarized in Table 2.7. 

Figure 2.61 Carbon monoxide conversion over various catalysts with respect to reaction temperature at an 02/C0 ratio of 4 and 200 ms residence time [89] (source IMM).

This system includes several mixing and heat exchange units. A concept for an integrated, microtechnology-based fuel processor was proposed by PNNF [8]. As examples for unit operations which may be included in future integrated systems the same publication mentions reactors for steam reforming and/or partial oxidation, water-gas shift reactors and preferential oxidation reactors for carbon monoxide conversions, heat exchangers, membranes or other separation components. 

Figure 5 and 6 show the contact time dependence of the concentration of each hydrocarbon represented by carbon monoxide conversion base for these catalysts. It is reasonable to derive the existence of the successive reaction step of olefins from the con-... 

As noted above, the reaction mixture most often used contains only the amount of oxygen required to oxidise either the carbon monoxide or some of the hydrogen, or a modest excess. This, together with knowledge of the relative activation energies (Figure 7.1) helps to explain the temperature profile of conversions and selectivity, as shown in a typical case in Figure 7.2. The maximum in the carbon monoxide conversion arises because... 

Perhaps the first published analysis of an RFBR was by Raskin et al. (4), who developed a qua si continuum model for a radial ammonia synthesis reactor and later applied it to carbon monoxide conversion (5). 

Summary data for different conversion/temperature conditions are provided in Tables 5-7. Rate constants were calculated from these data, and it was determined that although the operations at 140 kPa were influenced by mass transfer, this was not the rate-limiting step however, the reaction was mass transfer limited at 1000 kPa. The higher carbon monoxide conversion values and methane production observed for the monolith-supported nickel compared to pellets were explained to be due to the provision by the monoliths of smaller pore diffusion resistance and higher mass transfer rates at higher temperatures, primarily a result of shorter diffusion paths in thin alumina coatings on the monolith walls. 

Generally, in a conventional WGS system a two-step shift is used to obtain high CO conversion rates. In the first high-temperature shift reactor the major part of the CO is converted at high activity, whereas in the second shift reactor the rest of the CO (closely up to the thermodynamic equilibrium) is converted at low temperature and also low activity. Steam to carbon monoxide ratios above the stoichiometric ratio (higher than 2) are generally being used to attain the desired carbon monoxide conversion, but also to suppress carbon formation on certain catalysts. 

Kulkova, N.V. Temkin, M.I. Kinetics of the reaction of carbon monoxide conversion with steam. Zh. Fiz. Chim. (USSR) 1949,23 (6), 695-713. 

Shchibrya, G.G. Alekseev, A.M. Chesnokova, R.V. Lyudkovskaya, B.G. The study on preparation and calcination of zinc-chrome-copper catalyst for carbon monoxide conversion with steam. Kinet. Katal. 1971, 12, 1186. 

Primary steam reforming Secondary steam reforming Carbon monoxide conversion Carbon monoxide methanation Ammonia synthesis Sulfuric acid synthesis Methanol synthesis Oxo synthesis Ethylene oxide Ethylene dichloride Vinylacetate Butadiene Maleic anhydride Phthalic anhydride Cyclohexane Styrene Hydrodealkylation Catalytic reforming Isomerization Polymerization (Hydro)desulfurization Hydrocracking... 

The gas-phase reaction of carbon monoxide and steam to produce carbon dioxide and hydrogen has been studied in the presence of a Siemens ozonizer discharge. A factorial design was used to determine the effect of input electrical power, pressure, space velocity, and temperature on the conversion of carbon monoxide. With the aid of an empirical equation, derived from the factorial design data, the region of maximum conversion of carbon monoxide within the limits of the factors was determined. The rate of approach to thermodynamic equilibrium was investigated for one set of experimental conditions and was compared with previous work. The effect of changing the surface-to-volume ratio of the reactor upon carbon monoxide conversion was also determined. 

The prediction equation resulting from the statistical analysis of the data indicates that carbon monoxide conversion increases with pressure, temperature, and power input, and decreases with space velocity. Practically no reaction occurred in the absence of a discharge. 

No change in carbon monoxide conversion was found when the surface-to-volume ratio of the quartz reactor was changed by 33% from 4.85 cm.2/cm.3 to 6.45 cm.2/cm.3 by packing the reactor annulus with quartz wool. 

---