On the Composition of the Liquid Product of Synthesis from Carbon Monoxide and Water Vapor
Abstract Generated abstract
This study examines the composition of liquid products formed by synthesis from carbon monoxide and steam over an iron, copper catalyst at elevated pressures. Using distillation, chemical analysis, chromatography, and spectral studies, the authors compare product fractions and functional group composition at pressures including 10, 50, and 100 atm. The results indicate that increasing pressure raises the content of oxygen-containing compounds, especially fatty alcohols and acids, while reducing the hydrocarbon fraction and lowering the average molecular weight. The liquid product is characterized mainly as a mixture of normal paraffins, olefins, normal alcohols, and normal acids with 6 to 21 carbon atoms, with the highest probability near C12 and no detected aromatic or naphthenic hydrocarbons.
Full Text
ON THE COMPOSITION OF THE LIQUID PRODUCT OF SYNTHESIS FROM CARBON MONOXIDE AND STEAM
S. I. Smolyaninov, A. V. Kravtsov, I. V. Goncharov,
V. I. Sigaev, E. A. Samsikov
(Presented by the scientific-methodological seminar of the CTF)
The use of carbon monoxide for the synthesis of valuable organic compounds, in connection with its pollution of the atmosphere, is at present of great interest. The group composition of the products of synthesis from carbon monoxide and steam is determined mainly by the catalyst used and by the pressure. In the general case these products contain compounds of the fatty series of normal structure.
- Hydrocarbons consist of paraffins and $\alpha$-olefins, while the oxygen-containing compounds include alcohols and acids with small admixtures of aldehydes, ketones, and ethers. Aromatic and naphthenic hydrocarbons, despite the thermodynamic probability of their formation, have not yet been detected.
The ratio of alkanes to alkenes in the hydrocarbon portion of the product depends on the catalyst used. The greater the hydrogenating ability of the catalyst, the more saturated compounds there are.
-
The amount of olefins decreases in the catalyst series: iron, cobalt, nickel. The ratio between hydrocarbons and oxygen-containing compounds depends mainly on pressure.
-
The molecular weight of the product depends on a number of factors, such as pressure, temperature, space velocity, etc. We analyzed the products of synthesis from carbon monoxide and steam obtained on an iron–copper catalyst at elevated pressure. Some results are given in Tables 1 and 2.
As can be seen from the data obtained, with increasing pressure the amount of oxygen-containing compounds increases and the fraction of hydrocarbons decreases. The molecular weight of the product also decreases.
Chromatographic analysis confirmed the data of chemical ana-
Table 1
Distillation of the synthesis product by fractions
| Boiling limits | Yield, wt. %, pressure 50 atm | Yield, wt. %, pressure 100 atm |
|---|---|---|
| Fraction boiling up to 250°C | 50.21 | 52.43 |
| » » 350°C | 96.38 | 96.47 |
| Residue above 350°C | 3.62 | 3.53 |
Some experimental results
Table 2
| Pressure, atm | Degree of conversion | Molecular weight | Density, \(d_4^{20}\) | Refractive index | Oil layer: acid number, mg KOH/g | Oil layer: % acids, calculated as \(C_{11}\) | Oil layer: iodine number, g \(I_2\)/100 g | Oil layer: % olefins | Oil layer: hydroxyl number | Oil layer: % alcohols, calculated as \(C_{10}\) | Water layer: acid number, mg KOH/g | Water layer: % acids, calculated as \(C_3\) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 10 | 72,15 | 154,3 | 0,8017 | 1,4483 | 0,58 | 0,75 | 100,0 | 60,2 | 7,21 | 2,0 | 1,43 | 0,19 |
| 50 | 65,31 | 147,7 | 0,8217 | 1,4493 | 7,41 | 2,24 | 65,3 | 39,8 | 20,13 | 5,6 | 10,31 | 1,36 |
| 100 | 78,18 | 143,2 | 0,8242 | 1,4554 | 10,91 | 10,91 | 59,1 | 36,3 | 66,16 | 18,7 | 46,28 | 6,58 |
It was established that the liquid product is a mixture consisting predominantly of n-paraffins, olefins, n-alcohols, and n-acids of the fatty series, with the number of carbon atoms ranging from 6 to 21.
The probability of finding a given compound with a definite number of carbon atoms in the liquid product obeys the normal distribution law. In this case, the maximum probability falls on compounds with a number of carbon atoms equal to 12.
Spectral studies confirmed the absence of aromatic and naphthenic hydrocarbons; at the same time, for samples obtained at 50 and 100 atm, a significant increase was found in the intensity of absorption bands in the regions characteristic of fatty alcohols and acids.