Composition of the Liquid Product of Synthesis from Carbon Monoxide and Steam over an Iron-Copper Catalyst
Abstract Generated abstract
The study examines the composition of liquid products formed by synthesis from carbon monoxide and steam over an iron, copper catalyst at elevated pressures. Using chemical analysis, distillation, chromatography, and spectral methods, the authors characterize the hydrocarbon and oxygen-containing fractions and compare products obtained at different pressures. The results indicate that increasing pressure raises the content of acids and alcohols, lowers the hydrocarbon proportion and molecular weight, and yields mixtures composed mainly of normal paraffins, olefins, alcohols, and acids with 6 to 21 carbon atoms. Spectral evidence supports the absence of aromatic and naphthenic hydrocarbons, while the carbon-number distribution is reported to follow a normal law with a maximum near C12.
Full Text
On the Composition of the Liquid Product of Synthesis from Carbon Monoxide and Steam over an Iron–Copper Catalyst
S. I. Smolyaninov, A. V. Kravtsov, I. V. Goncharov,
B. I. Sigaev, N. A. Samsikov
(Presented by the Scientific-Methodological Seminar of the KhTF)
The use of carbon monoxide for the synthesis of valuable organic compounds, in connection with pollution of the atmosphere by it, is currently 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. The 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 series of catalysts: iron, cobalt, nickel. The ratio between hydrocarbons and oxygen-containing compounds depends mainly on the 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 over an iron–copper catalyst at elevated pressure. Some results are given in Tables I and II.
As can be seen from the data obtained, with increasing pressure the amount of oxygen-containing compounds increases and the proportion of hydrocarbons decreases. The molecular weight of the product also decreases.
Chromatographic analysis confirmed the data of the chemical analysis. It was established that the liquid product is a mixture,
Table 1
Distillation of synthesis products into fractions
| Boiling limits | Yield in weight percent, pressure 50 atm | Yield in weight percent, pressure 100 atm |
|---|---|---|
| Fraction boiling up to 250°C | 50.21 | 52.43 |
| Fraction boiling up to 350°C | 96.38 | 96.47 |
| Residue above 350°C | 3.62 | 3.53 |
Some results of experiments
Table 2
| Pressure | Conversion, % | Molecular weight | Density, g/cm³ | Refractive index | Oil layer: acid number, mg KOH/g | Oil layer: % acids, calculated as C₁₀ | Oil layer: iodine number, g per 100 g | Oil layer: % olefins | Oil layer: hydroxyl number | Oil layer: % alcohols, calculated as C₁₀ | Aqueous layer: acid number, mg KOH/g | Aqueous layer: % acids, calculated as C₃ |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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 |
consisting predominantly of n-paraffins, olefins, n-alcohols, and n-acids of the fatty series with a number of carbon atoms from 6 to 21.
The probability of finding a given compound with a certain number of carbon atoms in the liquid product follows 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.