CO rich gases

CO-rich gases are used for a number of important petrochemical reactions such as oxo-S5mthesis converting olefins to alcohols and acetic acid. The CO eontent of the s mgas is increased by decreasing the atomic ratio H/C in the feed gas. This is achieved at low H2O/C, use of naphtha instead of natural gas as feedstock, use of partial oxidation, and by addition of CO2 to the feedgas. Most of these measures increase the potential for carbon formation (refer to Chapter 5). 

Both of these reactions are exothermic and are favoured by reduction in temperature. Hence, while the products of the steam reforming reaction at higher temperatures ( 800 °C) are CO and H2, lower temperatures are used to produce methane-rich gases in this case, the overall reaction can be approximated by ... 

With an alumina coated vessel (but not with silica), Linnett et al. [511] also observed oscillatory behaviour inside the glow region. Instead of a single glow corresponding with reaction, they observed a series of successive glows, and these were particularly numerous in CO-rich mixtures. Linnett et al. worked with moist gases. However, similar oscillatory... 

In contrast to PGM catalysts, gold nanocatalysts are generally more active for CO oxidation than for H2 oxidation. In addition, gold catalysts are almost insensitive to CO2, and their activity is enhanced by moisture, the products of the two reactions. Gold catalysts are therefore strong candidates for the selective oxidation of CO in H2-rich gases [2, 35, 38,46, 52, 53,101,157,159, 183-200], a reaction needed to produce pure hydrogen for fuel cells. 

If the steam is completely or partly replaced by carbon dioxide, the result is another H2 to CO ratio, shifted towards a more CO-rich synthesis gas. The catalytic reforming of CH4 with CO2, first proposed in 1928 by Fischer and Tropsch, involves an environmental benefit, because two greenhouse gases are combined here resulting in a product gas which... 

PLASMA-CHEMICAL REFORMING OF LIQUID FUELS INTO SYNGAS (CO-H2) ON-BOARD GENERATION OF HYDROGEN-RICH GASES FOR INTERNAL COMBUSTION ENGINE VEHICLES... 

Schubert M.M., KahUch M.J., Feldmeyer G., Huttner M., Hackenberg S., Gasteiger HA. and Behm R.J. 2001. Bimetalbc PtSn catalyst for selective CO oxidation in Hj-rich gases at low temperatures, Phys. Chem. Chem. Phys., 3, 1123-1131. 

If required, relatively pure carbon monoxide can be recovered by cryogenic separation (i.e. condensation at very low temperatures), use of selective scrubbing solutions (for example CUAICI4 in toluene, the COSORB process) or solid adsorbents, and by other methods. Some CO recovery techniques are also applicable to the CO-rich (c. 70% molar) off-gases from basic oxygen furnaces and the leaner off-gases from air blast furnaces produced in steel manufacture, though operations of this type are still limited. 

The flexibility of the liquid phase process with respect to gas composition is particularly demonstrated by the fact that CO rich synthesis gases can be used which contain no hydrogen but steam (KSlbel-Engelhardt synthesis). The synthesis starts then by the formation of hydrogen from the shift reaction (2) which is followed by the hydrocarbon synthesis. The overall reaction is... 

CO-containing gases have also been used to reduce the catalysts. Davis and co-workers (22) reported that compared with activation with hydrogen-rich syngas, activation with CO or CO-rich syngas resulted in more active catalysts. Bukur and co-workers (23-25) reported that a catalyst reduced with H2 at 250°C had a higher activity but lower wax selectivity than the same catalyst reduced with CO at 280°C. 

In the SRC-11 process, the process steam is generated by direct gas-fired boilers and the process heating by direct gas firing. The fuels utilized are hydrocarbon-rich gas, or CO-rich gas, and purified syngas (i.e., no feed coal is used for fuel). It was shown that a 2 X 600 MW(t) PS/C-MHR can supply these thermal requirements principally by substituting for the fuel gases previously employed (Shenoy 1995). The displaced gases, which are treated already, may then be marketed. 

Wurzinger O, Reinhardt G (2004) CO-sensing properties of doped SnO sensors in Hj-rich gases. Sens Actuators B Chem 103 104-110... 

Yan J, Ma JX, Cao P, Li P. Preferential oxidation of CO in H2-rich gases over Copromoted Pt-y-Al203 catalyst. Catal Lett 2004 93 55-60. 

Besides hydrocarbons, autothermal reformers are also fed with pre-reformed H2-and CO-rich gas mixtures from a steam reformer (the so-called primary r ormer). In this case the ATR is also called secondary reformer. For the generation of synthesis gases for the ammonia synthesis, compressed air instead of pure oxygen is used. 

Guo Q, Liu Y. MnOx modified Co304-Ce02 catalysts for the preferortial oxidation of CO in H2-rich gases. Appl Catal B. 2008 82 19-26. 

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