Effect of Pressure on the Composition of Products Synthesized from Carbon Monoxide and Steam
Abstract Generated abstract
This study examines how pressure affects the composition of products formed in catalytic synthesis from carbon monoxide and steam. Experiments were conducted over an iron-copper catalyst on kieselguhr at 255°C and pressures of 10, 50, and 100 atm, with analysis of liquid product properties and the hydrocarbon composition of the C5 fraction. Increasing pressure markedly raised the proportion of oxygen-containing compounds, increased product density, and lowered average molecular weight, while the hydrocarbon fraction shifted from paraffin-rich to olefin-rich composition. The results suggest that, under these conditions, pressure influences product distribution through the catalytic mechanism and favors oxygenate formation while hindering hydrocarbon chain growth.
Full Text
EFFECT OF PRESSURE ON THE COMPOSITION OF PRODUCTS SYNTHESIZED FROM CARBON MONOXIDE AND STEAM
A. V. KRAVTSOV, I. V. GONCHAROV, A. K. GOLOVKO
(Presented by the scientific-methodological seminar of the organic departments of the Faculty of Chemical Technology)
The conditions under which a chemical process is carried out are the principal factor determining the composition and yield of the products formed. G. Kölbel and E. Forwerk [1] have most fully carried out studies on the influence of external conditions, mainly for a cobalt catalyst and only on the general indicators of the process.
An increase in pressure has a favorable effect both on the productivity of the catalytic process and on the ratio between the main and side reactions. Even when the pressure is raised to 5–6 atm, the reactions of methane formation and conversion are almost completely suppressed. As the pressure increases, the productivity of the process rises [2].
An increase in pressure has a favorable effect on the yield of oxygen-containing organic compounds [3].
Experiments to study the effect of pressure on the characteristics of synthesis from carbon monoxide and steam were carried out by us on an iron–copper catalyst deposited on kieselguhr. The experiments were conducted under pressures of 10, 50, and 100 atm. The main results of these studies are presented in Tables 1 and 2.
Table 1
Effect of working pressure on some characteristics of the liquid product of synthesis from carbon monoxide and steam
| Pressure, atm | Temperature, °C | Space velocity, h\(^{-1}\) | Iodine number, g I\(_2\)/100 g | Acid number, mg KOH/g | Hydroxyl number, mg KOH/g | Ester number, mg KOH/g | Carbonyl number, mg KOH/g | Density, g/cm\(^3\) | Molecular weight | Total % oxygen-containing compounds recalculated as \(n\)-butanol |
|---|---|---|---|---|---|---|---|---|---|---|
| 10 | 255 | 80 | 98.5 | 0.6 | 7.2 | 5.6 | 2.4 | 0.8017 | 154.6 | 3.2 |
| 50 | 255 | 200 | 77.3 | 7.4 | 32.4 | 35.2 | 6.3 | 0.8176 | 147.7 | 15.6 |
| 100 | 255 | 500 | 57.2 | 36.1 | 65.1 | 73.6 | 9.1 | 0.8243 | 143.5 | 34.3 |
As was to be expected, with increasing pressure the yield of oxygen-containing compounds increases significantly. At the same time, from the data in Table 1 it is evident that the molecular weight decreases and the density of the total liquid product increases.
Table 2
Yield of hydrocarbons of the C₅ fraction as a function of pressure
| Compound | Content, wt. %, 10 atm | Content, wt. %, 50 atm | Content, wt. %, 100 atm |
|---|---|---|---|
| 3-Methylbutene-1 | 2.1 | 4.6 | 9.8 |
| 2-Methylpentane (isopentane) | 27.0 | 25.6 | 7.2 |
| Pentene-1 | 3.1 | 24.7 | 45.3 |
| 2-Methylbutene-1 | 1.9 | 6.4 | 6.9 |
| n-Pentane | 59.0 | 31.7 | 26.3 |
| Pentene-2 (cis + trans) | 5.5 | 4.6 | 3.2 |
| 2-Methylbutene-2 | 1.4 | 2.4 | 1.3 |
| Total paraffin content | 86.0 | 57.3 | 33.5 |
| Total olefin content | 14.0 | 42.7 | 66.5 |
Probably, the process is determined entirely by the catalytic mechanism, and an increase in pressure, contrary to the requirements of thermodynamics, hinders the growth of the hydrocarbon chain; at the same time, however, favorable conditions are created for the formation of oxygen-containing compounds, which, at lower molecular weight, have a higher density than hydrocarbons.
With increasing pressure, owing to an increase in the proportion of oxygen-containing compounds, the hydrocarbon content decreases, as may be judged from the drop in the iodine number.
Table 2 gives the balance for hydrocarbons of the C₅ fraction. A clear dependence is observed between the ratio of paraffins and olefins. An increase in pressure leads to a change in this ratio in favor of olefins.
REFERENCES
- G. Kölbel, E. Forwerk. Khimiya i khimicheskaya tekhnologiya, 1957, No. 11, p. 122.
- G. Kölbel. Proceedings of the Fourth World Petroleum Congress, vol. 5, p. 265, 1956.
- H. Kölbel, F. Engelhardt. Erdöl u. Kohle. 133, 1, 1952.