Testing of Some Catalysts in the Synthesis from Carbon Monoxide and Water Vapor
Abstract Generated abstract
This study evaluates inexpensive iron-containing catalysts for synthesis from carbon monoxide and water vapor, a process for which catalyst selection had received little focused attention. Various industrial and laboratory catalysts, including Fischer-Tropsch iron-copper catalysts, fused iron, iron-chromium conversion and desulfurization catalysts, methanol synthesis catalyst, and zeolite-based preparations, were tested in a flow reactor at atmospheric pressure and 220 to 260°C after reduction and carbon monoxide treatment. Conversion data and gas chromatographic analyses were used to estimate organic product yields and integral selectivities for hydrocarbon formation versus hydrogen-producing side reactions. The results indicate that fused iron, conversion, and desulfurization catalysts can be applied to the process, while zeolite catalysts showed lower activity but relatively high selectivity, suggesting possible value in further development of zeolite-based compositions.
Full Text
TESTING SOME CATALYSTS IN THE SYNTHESIS FROM CARBON MONOXIDE AND WATER VAPOR
I. V. Goncharov, A. V. Kravtsov
(Presented by the scientific-methodological seminar of the organic departments of the chemical-technological faculty)
The industrial implementation of any catalytic process depends to a considerable extent on whether a highly productive and sufficiently inexpensive catalyst is available. In the literature on synthesis from carbon monoxide and water vapor, no special studies are described on the selection or creation of catalysts for the process under investigation. Most work has been carried out on scarce cobalt–thorium catalysts for Fischer—Tropsch synthesis [1, 2].
We have carried out a study of the possibility of using various catalysts in synthesis from carbon monoxide and water vapor. We deliberately narrowed the range of potentially suitable catalysts, leaving only the cheapest iron catalysts. Along with the traditional iron catalysts of Fischer—Tropsch synthesis, the catalysts tested included industrial catalysts widely used in various technological processes.
Table 1
Characteristics of the catalysts tested
| Catalyst name | Composition, wt. % |
|---|---|
| Iron–copper, deposited on kieselguhr (Fischer—Tropsch synthesis) | Fe — 39.0; Cu — 7.2; Mn — 6.4; K — 0.4; kieselguhr — 47.0 |
| Iron–copper, deposited on kaolin (Fischer—Tropsch synthesis) | Fe — 53.0; Cu — 2.1; Mn — 2.0; Al — 2.1; Ca — 5.2; Zn — 5.2; Cr — 1.0; K — 3.1; kaolin — 26.3 |
| Fused iron (synthesis of alcohols from carbon monoxide and hydrogen) | Fe — 93.0; Al — 3.7; K — 2.3 |
| Iron–chromium (conversion of carbon monoxide by water vapor (482)) | Fe — 91.0; Cr — 9.0 |
| Sulfur-purification catalyst | Fe — 81.2; Cr — 8.2; Cu — 10.6 |
| Methanol-synthesis catalyst | Zn — 64.2; Cr — 35.8 |
| Zeolite | Fe — 7.3; Cu — 1.3; Na — 1.2 |
| Zeolite | Fe — 7.3; Na — 2.5 |
| Deposited on alumogel | |
| Deposited on NaX zeolite |
Table 2
Main characteristics of catalysts in synthesis at atmospheric pressure
| Catalyst | T, °C | CO₂ | H₂ | CO | Theoretical yield of hydrocarbons, g/m³ | Integral selectivity ξCHₓ< | Integral selectivity ξH₂ |
|---|---|---|---|---|---|---|---|
| Iron–copper, deposited on kieselguhr | 240 | 41,0 | 17,0 | 39,0 | 92,6 | 0,72 | 0,28 |
| Iron–copper, deposited on kieselguhr | 250 | 50,0 | 15,0 | 31,0 | 113,4 | 0,78 | 0,22 |
| Iron–copper, deposited on kaolin | 240 | 34,0 | 14,0 | 31,0 | 85,4 | 0,69 | 0,31 |
| Iron–copper, deposited on kaolin | 250 | 49,0 | 20,0 | 14,0 | 120,0 | 0,70 | 0,30 |
| Fused iron | 240 | 40,0 | 17,0 | 35,0 | 85,2 | 0,68 | 0,32 |
| Fused iron | 250 | 50,0 | 14,0 | 30,0 | 114,4 | 0,79 | 0,21 |
| Iron–chromium for carbon oxide conversion (482) | 240 | 38,0 | 23,0 | 39,0 | 58,2 | 0,51 | 0,49 |
| Iron–chromium for carbon oxide conversion (482) | 250 | 44,0 | 20,0 | 32,0 | 85,4 | 0,64 | 0,36 |
| Desulfurization catalyst (482 Cu) | 240 | 42,0 | 20,0 | 38,0 | 77,2 | 0,62 | 0,38 |
| Desulfurization catalyst (482 Cu) | 250 | 50,0 | 20,0 | 20,0 | 112,3 | 0,70 | 0,30 |
| Methanol synthesis catalyst | 240 | 35,0 | 35,0 | 26,0 | — | — | — |
| Methanol synthesis catalyst | 250 | 39,0 | 39,0 | 18,0 | — | — | — |
| Zeolite composition Fe—7,3; Cu—1,3; Na—1,2 | 240 | 24,0 | 8,0 | 57,0 | 73,5 | 0,81 | 0,19 |
| Zeolite composition Fe—7,3; Cu—1,3; Na—1,2 | 250 | 28,0 | 9,0 | 48,0 | 70,7 | 0,77 | 0,23 |
| Zeolite composition Fe—7,3; Na—2,5 | 240 | 23,0 | 11,0 | 59,0 | 62,5 | 0,73 | 0,27 |
| Zeolite composition Fe—7,3; Na—2,5 | 250 | 28,0 | 9,0 | 51,0 | 83,2 | 0,82 | 0,18 |
| Sprayed onto alumogel | 240 | 18,0 | 18,0 | 60,0 | — | — | — |
| Sprayed onto alumogel | 250 | 30,0 | 30,0 | 46,0 | — | — | — |
| Sprayed onto zeolite | 240 | 10,0 | 10,0 | 76,0 | — | — | — |
| Sprayed onto zeolite | 250 | 18,0 | 18,0 | 60,0 | — | — | — |
In addition, zeolite catalysts were prepared by ion exchange of Na\(^+\) ions for Fe\(^{3+}\) and Cu\(^{2+}\) in NaX zeolite. Supported catalysts were prepared by decomposing iron pentacarbonyl on the surface of an inert carrier.
The characteristics of the catalysts tested in the synthesis from carbon monoxide and water vapor are given in Table 1.
In all experiments catalysts of the 2–3 mm fraction were used. The catalysts were tested in a flow-type unit at atmospheric pressure. Before operation the catalyst was reduced with hydrogen for 3 hours at a temperature of 350°C. The reduced catalyst was treated with dry carbon monoxide for 4 hours at a temperature of 210°C. The ratio of carbon monoxide to water vapor was kept constant from experiment to experiment and was equal to 3:1.
The catalysts were tested in the temperature range 220–260°C.
During the synthesis, gas samples were taken for analysis at 1-hour intervals. The composition of the exit gas was determined using an KhT-8 chromatograph.
On the basis of the analytical data, according to the method of I. F. Bogdanov [3], the degree of conversion and the total yield of organic synthesis products were calculated. Knowing the amount of carbon monoxide converted in the target reaction of synthesis of organic compounds and the amount of carbon monoxide consumed in the side reaction of hydrogen formation, the integral selectivity for the target reaction (\(\xi_{\mathrm{CH_2}}\)) and for the side reaction (\(\xi_{\mathrm{H_2}}\)) was calculated.
Some results of the calculations are given in Table 2.
It is evident from Table 2 that the selectivity of the tested catalysts for the main and side reactions is different. High activity and selectivity were shown by the conversion catalyst and the desulfurization catalyst. The production of these catalysts has been mastered by industry. Their composition and preparation technology are much simpler than those of Fischer–Tropsch synthesis catalysts.
The activity of the tested zeolite catalysts is lower than that of the precipitated and fused catalysts. They are characterized by high selectivity for the target reaction. The dependence of the technological indices of these catalysts on the degree of ion exchange makes it possible to suppose that the tested catalysts were not optimal. By using zeolite catalysts of another composition, it may be possible to find a highly active and selective catalyst.
Conclusions
A study has been carried out of the possibility of using various inexpensive iron catalysts in the synthesis from carbon monoxide and water vapor at atmospheric pressure. It has been shown that a fused iron catalyst for the synthesis of higher alcohols, as well as conversion and desulfurization catalysts, can be used in the process under investigation. The high selectivity of zeolite catalysts prepared in the laboratory has been established. The promise of further work on the creation of zeolite-based catalysts has been noted.
LITERATURE
- T. Kelbel, E. Forverk. “Chemistry and Chemical Technology,” 1957, No. 11, p. 122.
- H. Kölbel, J. Küschel, H. Hammer. Liebigs Ann., 32, 8, 1952.
- I. F. Bogdanov, P. V. Lavrov, G. V. Grebenshchikova. Proceedings of the IGI, Academy of Sciences of the USSR, 18, 94, 1962.