LT3622B - Supported catalyst for hydrocarbon synthesis - Google Patents

Abstract

A Fischer-Tropsch catalyst for converting syngas to hydrocarbons and comprising Co on an alumina support is characterised by the additional presence of Pt, Ir and/or Rh on the support in an amt. less than that of the Co but sufficient to give a finished catalyst with a positive X-ray diffraction pattern (pref. with peaks in the 2-theta range of 65-70 deg).

Description

The present invention relates to catalysts, in particular to catalysts for the conversion of synthetic gases into hydrocarbons.

Reactions of the conversion of a mixture of carbon and hydrogen oxides (so-called synducts) to higher hydrocarbons on metal catalysts have been known since the beginning of the century. This reaction is commonly referred to as Fisher / Tropso fusion or F-T fusion. F-T synthesis was used on an industrial scale during World War II in Germany; In 1944, all 9 F-T plants worked in Germany, preferring a catalyst consisting of cobalt, magnesium oxide, thorium oxide, and kieselguhr in the following relative ratios of 100: 5: 8: 200. Subsequently, for economic reasons, most of the thorium oxide was replaced by magnesium oxide. Currently, industrial Fischer-Trops industrial plants in South Africa use a catalyst based on precipitated iron, which contains various stabilizing and product distribution promoters.

Common F-T catalysts include nickel, cobalt and iron. Nickel was apparently the first material known to be a catalyst for the conversion of fusion gas to hydrocarbons with good methane yields. such as R.B. Andersen, The Fisner-Tropsch Synthesis (1984), p. 22 Academic. Pres /. Iron and cobalt are capable of producing higher hydrocarbon chains and are therefore preferred over other catalysts for the production of liquid hydrocarbons. However, other metals may also be catalysts for the conversion of fusion gas. Among Group VII metals, ruthenium is a very active catalyst for hydrocarbon synthesis. At low temperatures its activity is higher than that of Fe, Co or Ni and the yields of heavy hydrocarbons are high. At high pressures, high amounts of high molecular weight ash can be obtained with this catalyst. Other active metals, such as rhodium, provide significant amounts of oxidized material / see. Ichikawa, Chemtech. 6, 74 (1982). Osmic activity was found to be moderate and Pt, Pd and Ir low / see. Richler, Advanced in Catalysis, vol. IV, Academic Press, N.Y. (1962), R.B. Anderson, The Fisher-Tropsch Synthesis, Supra and Vannice, Journal of Catalysis, 50, 228-236 /.

Other metals such as rhenium, molybdenum, chromium have also been tested, but have shown very little activity, and most of the product is methane (see R.B. Anderson, The Fisher-Tropsch Synthesis, Supra).

Combinations of various metals can also be successfully used in the F-T process. By adding nickel to the cobalt catalyst, the amount of methane / F in the F-T synthesis product can be increased. Catalysis you IV Leinhold Publishing Co. (1956), 29 pages /. U.S. Patent 4,088,671, entitled Sin-Gas Conversion to a Cobalt-Rhenium Catalyst, by T.R. Kobiiinski points out that the addition of a small amount of ruthenium to cobalt increases the overall activity of the catalyst and reduces the amount of methane in F-T synthesis compared to pure cobalt catalyst. Thus, these sources show that the combination of two or more metals active in F-T synthesis yields an active F-T catalyst having characteristics analogous to the bonded characteristics of each individual component.

There are reports that cobalt combinations with inactive metals in the synthesis of F-T are used to convert syn-gas into specific products and, in some cases, under specific conditions. In U.S. Patent 3,988,344, Nakaodji stated the combination of cobalt with tungsten and Group VIII metal to produce more methane from the synthesis gas. Kifton, U.S. Pat. No. 4,390,734 and Kokaji, Japanese Pat. 37/130932 describes Co and Rh for the production of oxidized products such as glycols and aldehydes.

Fisher-Trops catalysts consisting of a combination of cobalt with either platinum or palladium deposited on various carriers, including alumina, have been described by Sapienco in co. However, those catalysts are based on the fact that they are made from metal carbonyls in the form of solid solutions on solid supports and differ in the coating on the carrier and on the X-ray, thereby obtaining a catalyst with a unique diffractive image of solid support structures . If Sapienco with co. the catalyst being alumina, it does not produce any diffraction peaks in the 2Q range from 65 to 75 ° C. In X-ray diffraction, Q corresponds to the refraction angle.

Combinations of metals with some oxide-like carriers are also reported to increase the yield of hydrocarbons in F-T synthesis. Pressure with co U.S. Pat. P 4,595,703, entitled Synthetic Hydrocarbons, reports the use of titanium dioxide as a carrier of cobalt and cobaltothorium. In this case, the carrier increases the activity of the metal (s) to form hydrocarbons. Indeed, titanium dioxide belongs to that class of metal oxides which are known to exhibit strong metal-carrier interactions and increase the activity of a series of metals in F-T synthesis / see, e.g., M.A. Vannice, Yournal of Catalysis, 74, 199 (1982) /, the combination of titanium dioxide and two or more metals, as shown, increases the activity of the catalyst in F-T synthesis. Moldin in U.S. Pat. 4,568,663 stated the use of a combination of cobalt and rhenium, or cobalt, rhenium and thorium on a carrier, titanium dioxide, for the production of hydrocarbons from methanol and synthesis gas.

In European Patent Applications EP 110449, EP 14288, EP 167215 and EP 1 8204, Sholl Intern. discloses an improved F-T catalyst consisting of cobalt activated with at least one of the metals of the group consisting of zirconium, titanium and chromium, preferably using silica, alumina or aluminosilicate as carrier. A Group VIII precious metal additive to a cobalt catalyst activated by zirconia is disclosed in European Patent Application EP 2 1598 which discloses an increase in the activity of a cobalt catalyst already activated by zirconia by the addition of platinum. Boll's work demonstrates that the addition of a metal from Group VIII to a Fisher-Tropšc catalyst is useful only if the catalyst already contains a well-known promoter such as zirconia as a major component of the catalyst.

We have unexpectedly found that the addition of platinum, iridium or rhodium to a cobalt catalyst on alumina significantly increases the activity of the catalyst during the conversion of the synthesis gas to the hydrocarbons, even in the absence of an additional metal or metal oxide type promoter. A surprising feature of the present invention is that the increase in activity is much greater than would have been expected when the individual components were added, especially considering that metals such as platinum, iridium and rhodium are not very active F-T catalysts. / 2 / the combination of cobalt and alumina alone does not exhibit a pronounced increase in activity (7 in FT synthesis compared to combinations of cobalt and other carriers, and / / 3) the addition of cobalt to a second metal does not show any increase in methane or oxidized product yield, that in the conversion of synthesis gas to platinum or iridium the main product is methane and on rhodium the oxides of the compounds.

In the present invention, it has been found that the synthesis gas consisting of hydrogen and carbon monoxide can be converted into liquid hydrocarbons using a catalyst consisting of cobalt, active in the synthesis of FT, and at least one non-load-loading metal selected from the group consisting of platinum, iridium and rhodium on a carrier - alumina; the prepared catalyst gives positive peaks in the diffraction pattern in the range 2 Q from 65 to 70 ° C, where Q is the refraction angle. The amount of second metal is relatively lower than that of cobalt. It is good when the catalyst contains about 5-60 wt. % cobalt and the second metal content is about 0.1-60% of the amount of cobalt in the catalyst. Gamma-alumina is recommended.

It has been found that the addition of one or more metals from the platinum group, iridium and rhodium to the catalyst consisting of cobalt on a carrier, alumina, significantly increases the activity of the synthesis gas to hydrocarbons. Platinum, iridium and rhodium by themselves are not very active catalysts for Fisher's Tropso synthesis, and it was unexpected that the addition of other noble metals (inactive in F-T synthesis) to the cobalt catalyst did not significantly increase activity. The addition of platinum, iridium, or rhodium to the cobalt catalyst, unchanged, also does not show any improvement if the catalytic components are not on the alumina but on other carriers such as silica or titanium.

The present invention is more fully understood by reference to the drawings:

FIG. 1 - dependence of carbon monoxide conversion on the amount of platinum in the catalyst; the catalyst is deposited on alumina and contains cobalt and platinum;

FIG. 2 - dependence of carbon monoxide conversion on the amount of iridium in the catalyst; the catalyst is deposited on alumina and contains cobalt and iridium;

FIG. 3 - dependence of carbon monoxide conversion on the amount of rhodium in the catalyst; the catalyst is deposited on alumina and contains cobalt and rhodium;

FIG. 4 - dependence of the conversion of carbon monoxide on the content of cobalt in catalysts deposited on alumina and consisting solely of cobalt or cobalt and platinum;

FIG. 5 - dependence of carbon monoxide conversion on the content of cobalt in catalysts deposited on alumina and consisting solely of cobalt or cobalt and iridium;

FIG. 6 - Dependence of the conversion of carbon monoxide on the content of cobalt in catalysts deposited on alumina and consisting solely of cobalt or cobalt and rhodium;

FIG. 7 - Dependence of the conversion of carbon monoxide on the content of platinum in catalysts deposited on alumina and consisting of cobalt and palladium;

FIG. 8 is an X-ray diffraction pattern for a catalyst of the present invention consisting of cobalt and platinum deposited on alumina;

FIG. 9 is an X-ray diffraction image of a catalyst according to the present invention consisting of cobalt and rhodium deposited on alumina;

'N:' s

FIG. 10 is an X-ray diffraction pattern for a catalyst of the present invention consisting of cobalt and rhodium deposited on alumina.

The active catalytic part of the catalyst according to the present invention is cobalt and one or more metals selected from the group consisting of platinum, iridium and rhodium deposited on alumina; by the way, the amount of the second metal is relatively smaller than that of cobalt. The prepared catalyst shows a positive X-ray diffraction pattern with peaks in the range of 2 Q from about 65 to about 70 ° C. It has been found that such a catalyst has high activity in the conversion (conversion) of the synthesis gas (a mixture of hydrogen and carbon monoxide) to a mixture of paraffinic hydrocarbons. As has been said, cobalt has long been known to be an active catalyst for F-T synthesis. The addition of rhenium to a cobalt catalyst has been known to increase its activity, but ruthenium itself is also known to be active in the F-T process. Our invention has shown that among the metals inactive in the F-T process, some metals in the periodic table group VIII added to the cobalt catalyst on the support increase the activity of the catalyst while other metals in that group do not increase the activity. Although more carriers were studied in this work, and an increase in activity was observed only for alumina, the disclosure of another carrier with analogous properties would not be unexpected. Cobalt is added to the alumina carrier to about 60 wt. % catalyst, including cobalt. Optimum amounts are from about 10 to 45 lbs. %. The amount of platinum and / or iridium and / or rhodium is in the range of about 0.1 to 50% by weight. % by weight of cobalt, preferably about 0.1 to 30% by weight. %, and more preferably from about 0.5 to 20% by weight. %.

In addition to cobalt and one or more metals selected from the group consisting of platinum, iridium, and rhodium, it is useful to include a small amount of the metal oxide promoter in an amount of about 0.1 to 5% by weight. %, preferably about 0.2 to 2% by weight. % based on the total weight of the catalyst. The promoter (promoter) is convenient to collect from the periodic table group IIIB, IVB and VB elements, lanthanides and actinides. Promoting oxides can be selected, for example, from S ₂ O ₃ , V ₂ O ₃ ,

Ce ₂ O ₃ , La ₂ O ₃ , Pr ₂ O ₃ , O ₂ , / ^ c ₂ O ₃ , 0 ₂ , Nd ₂ O ₃ , CeO ₂ , \ Ζ ₂ Ο ₃ or Nb ₂ O ₅ . The preferred oxide is La ₂ O ₃ or a mixture of lanthanides enriched with lanthanum. Oxides such as MnO or MgO can also be incorporated. Although not essential, the use of these metal oxides is common in the art as it is believed to promote the formation of high boiling products while maintaining high catalyst activity. However, that catalyst remains highly active and selective without the addition of a promoter.

The catalytic activity of metals and the promoting metal oxide, if present, is increased on alumina. While other carriers may be used, it has been found that catalysts with silica and titanium have significantly less activity and cannot be improved by adding one or more metals from the platinum, iridium and rhodium groups.

In order to be more effective as a carrier, alumina must have low acidity, high surface area and high degree of purity. These properties are necessary for the catalyst to have a high activity, a low rate of deactivation, and to obtain high molecular weight hydrocarbons. The alumina carrier has a surface area of at least about 100 m ² / g, preferably about 150 m / g. The pore size is at least about 0.3 m ³ / g. The catalyst carrier must be of high purity. These include elements such as sulfur and

LT f * f *

The amount of Q phosphorus that adversely affects the catalyst carrier should be less than 100 parts per million. and preferably 50 parts per million. Although gamma-alumina is generally used and is most suitable, a number of other alumina structures can meet these conditions and, when properly prepared, become suitable carriers. For example, etha-alumina, xy-alumina, theta-alumina, delta-alumina, kappa-alumina, bohemite and pseudobohemite can also be used as carriers.

The method of applying the active metals and the oxide-promoter to the alumina carrier is not practical and may be selected from a variety of methods known to those skilled in the art. One suitable well-known and used technique is impregnation with a small amount of solution. In this process, the metal salts are dissolved in an amount of a suitable solvent which is sufficient to fill the pores of the catalyst alone. Alternatively, the metal oxides and hydroxides are precipitated together from the aqueous solution by the addition of a precipitating agent. In another embodiment, the metal salts are mixed with the wet carrier in a suitable mixer until a substantially homogeneous mixture is obtained. In the present invention, when impregnated with a small amount of solution, the catalytically active metals can be deposited on a carrier using an aqueous or organic solution. Suitable organic solvents include, for example, acetone, methanol, ethanol, dimethylformamide, diethyl ether, cyclohexane, xylene and tetrahydrofuran. If Co (N0 ₃ ) _{2 is} used as the cobalt salt, aqueous impregnation is preferable.

Suitable cobalt compounds include, for example, cobalt salts: cobalt nitrate, cobalt acetate, and cobalt chloride, by the way, when impregnated with an aqueous solution. Suitable platinum, iridium and rhodium compounds include, for example, nitrates, chloLT 3622 B iodides and ammonia complexes. The promoter may be incorporated into the catalyst, for example as nitrate or chloride. After aqueous impregnation of catalysts for 3-6 hours. dries at 110-120 ° C. If impregnated with organic solvents, the catalyst must first be dried in a rotary evaporator at 50-60 ° C under reduced pressure and then dried at 110-120 ° C for several hours.

The dried catalyst is calcined in an air stream by slowly raising the temperature to an upper limit between 200 and 500 ° C, preferably between 250 and 350 ° C. The preferred temperature rise rate between 0.5 and 2 ° C / min and the highest temperature retains the catalyst for 23 hours. Repeat the impregnation procedure as many times as necessary to obtain the required amount of metal. Impregnation with cobalt, platinum, iridium or rhodium and with the promoter (if present) can be performed simultaneously or in separate steps. If impregnated separately, the order of impregnation with active components can be varied.

The calcined catalyst is reduced with hydrogen prior to use. This is conveniently done in a stream of hydrogen at atmospheric pressure at a flow rate of between 30 and 100 cm / min if it reduces about two grams of catalyst. For large amounts of catalyst, the flow rate must be increased accordingly. The temperature is increased at a rate between 0.5 and 2 ° C per minute from room temperature to a maximum of 250 to 450 ° C, preferably 300 to 400 ° C, and maintained at that maximum temperature for 6 to 24 hours, preferably 10 to 25 hours. .

The reduced catalysts of the present invention differ in that they exhibit different X-ray diffraction patterns for alumina. Namely, diffraction peaks atLT 3622 B u

a 2 ° range of 65 to 70 degrees clearly shows that there is no solid solution covering the carrier surfaces as reported by Sapienc in co. U.S. Patent 4,396,839, discussed above, clearly demonstrates that the catalyst according to the present invention is different from those described in Sapienco et al. patents.

The diffractive images of the catalysts of the present invention are shown in Figures 8, 9 and 10. These diffraction patterns were obtained for the catalysts according to Examples 6, 9 and 12, respectively. The catalyst was reduced and passivated before the diffraction pattern was recorded.

After the reduction step, the catalyst can be oxidized and reduced before use. In the oxidation step, the catalyst is treated with dilute oxygen / 1-3% acetone / room temperature for 1/2 to 2 h before raising the temperature at the same rate and to the same temperature as during the calcination step. After being kept at the highest temperature for 1-2 hours, the air is slowly supplied and continued in the air at the highest temperature for another 2 to 4 hours. The second reduction is performed under the same conditions as the first reduction.

The reactor used for the synthesis of hydrocarbons from sintered gas is selected from a variety of types well known to those skilled in the art, for example, with a fixed bed, a fluid bed, a fast-setting bed, or a slurry. The particle size of the catalyst for the stationary or fast-setting layer is preferably between 0.1 and 10 mm, and more preferably between 0.5 and 5 mm. For other types of work, particle sizes between 0.01 and 0.2 mm are preferred.

Syngas is a mixture of carbon monoxide and hydrogen and can be obtained from any source known to those skilled in the art, such as natural gas reforming or partial oxidation of carbon. A suitable molar ratio of H ₂ : CO is from 1: 1 to 3: 1, more preferably from 1.5: 1 to 2.5: 1. When used in the catalyst of the present invention, carbon dioxide is an undesirable component but does not adversely affect the activity of the catalyst. On the other hand, all sulfur compounds must be present in very small quantities, preferably less than 1 part per million.

The reaction temperature is preferably about 150 to 300 ° C, preferably between 175 and 250 ^u C. Total pressure may range from atmospheric to about 100 atm, preferably between 1 and 30 atm. The gas volume per hour, based on the total amount of feedstock synthesis gas, is suitable for between 100 and 20,000 cm of gas per gram of catalyst per hour, more preferably between 1000 and 10,000 cm g / h, where the gas volume per hour is determined as gas. volume (at standard temperature and volume) per unit weight of catalyst per hour.

The reaction product is a complex mixture, but the basic reaction can be written as follows:

nCO + 2nH ₂ ---> / -CH ₂ - / n + nH ₂ O, where / -CH ₂ - / n is a straight chain hydrocarbon with carbon number n.

F-T synthesis products are usually paraffins, or olefins, or spirits. The number of carbon atoms is in the range of 1 to 50 and more.

In addition, many catalysts, such as those based on iron

CO + H ₂ O ---> H ₂ + CO ₂

For cobalt catalysts, the rate of that last reaction is very low. The same low reaction rate is observed for catalysts in which platinum, iridium or rhodium are added to cobalt.

The hydrocarbon products of F-T syntheses are distributed from methane to high-boiling compounds with the so-called Schulco-Flori distribution, well known to those skilled in the art. Mathematically, the Schulco-Flori distribution is expressed by the Schulco-Flori equation:

W _x = (1-a) l, d ^{1 1} where i represents the number of carbon atoms, a is the Shuclo-Flori partition coefficient which measures the ratio of chain growth rate to chain growth rate plus chain breaking rate, and W _x is the weighted product of the number of carbon atoms in part i.

The products obtained on the catalyst of the present invention generally follow the Schulco-Flori distribution, except that the methane yield is lower than would follow from that distribution. This means that methane appears to be produced by an additional mechanism.

It is well known and also illustrated in the following examples that the metals of the platinum, iridium and rhodium group, taken separately, are low activity catalysts in the synthesis of F-T and the resulting product is essentially methane and in the case of rhodium an oxygen containing compound.

The catalysts of the present invention will now be described by reference to the following examples.

^14th

The following examples describe the preparation of the various catalysts and the results obtained by testing those catalysts for the conversion of the synthesis to hydrocarbons.

Prior to the test, each catalyst shall be specifically treated: reduced by hydrogen at 3000 cm / g / h by heating the catalyst at 1 ° C / min to 350 ° C and maintaining at that temperature for 10 hours. In these tests, the synthesis gas consisting of 33% by volume of carbon monoxide and 67% by volume of hydrogen passes over 0,5 g of catalyst at atmospheric pressure at 185, 195 and 205 ° C as follows:

50 min 195 ° C 20th min 205 ° C 30th min 185 ° C 50 min 195 ° C

Synthesis gas flow rate: 1 680 cm ³ / g catalyst / 'n. The products obtained in the reactor are analyzed by gas chromatography. The catalysts were compared based on the results obtained over a period of 10 to 30 hours at current.

example

Catalyst containing no cobalt and no second metal

This example describes the preparation of a control cobalt catalyst, which is further used as a reference. The catalyst is produced as follows:

Prepare the solution by dissolving 17.03 g of cobalt nitrate,

Co (N0 ₃ ) ₂ 6 H ₂ 0 and 0.76 g of a mixture of rare earth metals nitrates, RE (NO ₃ ) ₂ , where RE represents the following compounds: 66% La ₂ O ₃ , 24% Nd ₂ O ₃ , 8, 2% Pr ₆ O _n , 0.7% CeO ₂ and 1.1% other oxides / Molycorp 5247/30 ml distilled water. The entire solution was stirred with 26 g of Ketjen CK300 gamma-alumina calcined for 10 h at 500 ° C. The resulting catalyst is dried, then heated in a thermostat for 5 h at 115 ° C. The dried catalyst is then calcined in air at a temperature of 1 ° C / min up to 300 ° C and maintained at that temperature for 2 h. The prepared catalyst contains 12 wt. % cobalt and 1 wt. % of the rare earth oxides, and the rest is alumina. In Table I, this catalyst is designated a. The above procedure was repeated to produce catalyst b (Table I).

The test results for these catalysts are shown in Table I. In this and other tables, selectivity is defined as the percentage of carbon monoxide converted to the product indicated.

Table I

temp. ° C catal. CO conversion c ₂ + ch ₄ co ₂ selectivity selectivity selectivity 185 a 7th 91.2 7.1 1.7 b 11th 91, 9 7.0 1.1 195 a 12th 90.1 8, 8 1.1 b 18th 90.3 8.9. 0.8 205 a 21st 87.8 11.2 1.0 b 29th 86, 8 12.3 0.9 This example shows that cobalt catalyst distinguished

good selectivity for ethane and hydrocarbons with longer chain but low selectivity for methane and carbon dioxide.

Examples 2, 3 and 4

Catalysts containing Pt, Ir and Rh but not containing Co

In the preparation of catalysts containing 1 wt. % Pt, 1 wt. % Ir and 1 wt. % Rh but without cobalt utilizes the procedure described in Example 1. These catalysts tested showed very low activity (see Table II), which could be expected, since it is known that Pt, Ir, and Rh are two-thirds less active than Co (see e.g. MA Vannice, Yournal if Catalysis). , v. 50 pp. 228-236).

Table II

Example # Co. the second metal CO conv. C2 + sel. CH ₄ sel. CO 2 s s Σ. 2 0 Pt 1.0 1 11.2 47.7 41.1 3 0 Yes 1.0 _L 12, 4 47.4 40.2  4 0 Rh 1.0 1 12, 8 50.4 36.8

all boilers were supplied with 1% of the earth's alkali metal oxides.

It is clear from the results of Table II that the high activity of the catalysts of the present invention is not due to the additive effect of the catalytic components but is due to more complex factors.

Examples 5-14

The catalyst is prepared according to Example 1, except that the solution is mixed with different amounts of tetraamine platinum dinitrate, iridium tetrachloride or rhodium dinitrate. Catalysts containing 12% cobalt and different amounts of Pt, Ir and Rh are obtained, which are shown in Table III. The tests were performed according to the methodology described above.

Table III

For example No. Co. metal CO conv. C ₂ + sel. CH ₄ sel. co ₂ sel. type , Sun. % 5 12th Pt 0.1 28th 90, 1 9.4 0.5 6th 12th Pt 0.1 29th 89.3 10, 4 0.7 7th 12th Pt 0, 3 30th 88.7 10.5 0, 8 8th 12th Pt 1.9 25th 88, 8 10, 5 1.2 9th 12th Yes 0.1 30th 89.5 9.7 0.8 10th 12th Yes 0.3 31st 89.1 9.9 1.0 11th 12th Yes 1.0 31st 89.1 9.9 1.0 12th 12th Rh 0.1 27th 88.0 11.0 1.0 13th 12th Rh 0.3 27th 89, 0 10.2 0, 8 14th 12th Rh 1.0 25th 88.5 10.8 0.7 To the catalyst of all composition entered 1% rare of land of metals

of oxides.

Comparing the results of Tables I and III, we can see that the activity of the catalysts is clearly increased when Pt, Ir or Rh is added to the Co catalyst. Catalytic activity reaches its highest level with a second metal content of only 0.1%.

15-22 Examples

Catalysts having Co and Pt, Ir or Rh

These catalysts are prepared according to the method described in Examples 1 and 5-14 by introducing various amounts of cobalt and various amounts of platinum, iridium or rhodium plus 1% of the rare earth oxides into the catalyst.

The results obtained for catalysts with 20% Co and 0.17% 5 Pt, Ir or Rh are shown in Table IV. For comparison, Table IV includes the results for catalysts with and 40% cobalt without second metal. The results obtained are also presented. FIG. 4, 5 and 6.

Table IV

Example of Co the second type, metal s v. % CO conv. C ₂ + sel. ch ₄ sel. co ₂ sel. No. 15th 16th 20th 20th Pt 0.17 20th 40 89, 4 85, 9 9.7 12, 9 0.9 1.2 17th 20th Yes 0.17 41 86.5 12.2 1.3 18th 20th Rh 0.17 42 87.0 12.0 1.0 19th 20th 40 40 Pt 0.33 20th 53 89, 4 83, 1 9.6 14.7 1.0 2.2 21st 40 Yes 0.33 53 84.0 13, 8 2.2 22nd 40 Rh 0, 33 53 83, p 14.7 2.1 IV tables and FIG. 4 , 5 and 6 results shows when

the addition of Pt, Ir 15 or Rh to the cobalt catalyst is significantly more pronounced at high

Co. for quantities.

23-25 Examples

Catalysts containing combinations of Co and Pt, Rh or Ir

These catalysts are obtained in the same manner as in Example 1 by the addition of two or three metal salts: tetraamine platinum dinitrate iridium trichloride or rhodium diLT 3622 B nitrate. Results for catalysts containing 12 wt. % Co and two or three of the metals: Pt, Ir or Rh, are given in Table V.

Table V.

For example No. Co. the second metal CO conv. C ₂ + sel. ch ₄ sel. CO ₂ sel. type, sv % 23rd 12th Pt 0, 06 25th 87.4 12.6 1.1 Yes 0, 05 24th 12th Yes 0.05 26th 86, 8 13.2 1.2 Rh 0.05 25th 12th Pt 0.05 26th 96, 8 13, 2 1.3 Rh 0, 05

The results in Table V show that the addition of the second metals selected from the group consisting of Pt, Ir or Rh to the cobalt catalyst increases the catalytic activity in the same way as the addition of only one of these second metals. This means that the second metal can be introduced into the catalyst in various combinations of Pt, Ir and Rh.

26-35 Examples

Catalysts containing Co and Pt, Ir or Rh, supported on a support other than alumina

These catalysts are obtained by the addition of Pt, Ir or Rh salts as described in Example 1. SiO ₂ / Grade 59 from Davison Chemicals / and TiO ₂ / P ₂₅ of Degussa / were used as carriers in these examples. The test results are shown in Table VI. For comparison, the results for the catalysts without Pt, Ir or Rh on SiO ₂ and TiO _{2 are} included in the table.

Table VI

For example 'No. Co. the second metal CO conv. ^C 2 + sel. ch ₄ sel. co ₂ sel. type, sv % The bearer - silica 26th 12th - - 11th 90.2 8, 6 1.2 27th 12th Pt 0.1 12th 89.1 9.1 1.8 28th 12th Pt 1.0 14th 89, 0 9.0 2, 0 12th 86.1 11.1 2.8 29th 12th Yes 0.1 13th 90.8 7.7 1.5 30th 12th Rh 0.1 11th 90.0 8.0 2, 0 The bearer - titanium dioxide 31st 12th - 11th 87.7 11.7 0.6 32 12th Pt 0, i 12th 86, 8 11.4 1.8 33 12th Pt 1.0 14th 82.5 12, 6 4.9 12th 79, 5 14.5 6.0 34 12th Yes 0.1 13th 87.5 11.1 1.4 35 12th Rh 0.1 12th 85.1 11.2 3.7 These results shows that activity increase, which we watched. pri dye small quantities Pt, Ir or Rh to cobalt k; ataliza thorium, carried i on aluminum ok- binds, to cases, when carriers uses sili cio ar

titanium dioxide - undetectable.

36-40 Examples

Catalysts containing Co and other Group VIII metals, inactive in the Fisher-Trops process

These catalysts are used to show the difference between cobalt catalysts containing Pt, Ir or Rh and cobalt catalysts containing other Group VIII metals inactive in the Fisher-Trops process. The catalyst is prepared in the same manner as in Example 1 except that it adds different amounts of tetraamine palladium dinitrate, nickel dinitrate and osmium trichloride.

Test results for these catalysts are shown in Table VII.

Table VII

For example No. Co. the second metal CO conv. C ₂ + sel. ch ₄ sel. co ₂ sel. type, sv % 36 12th Pd 0.1 22nd 87, 8 12.2 1.7 37 12th Pd 0.3 18th 88.3 10, 9 0.8 38 12th Pd 1.0 8th 83, 0 15, 6 1.4 39 12th Ni 0, 3 16th 89, 6 9.5 0.9 40 12th Os 1.0 18th 90.2 9.0 O co These results clearly indicate that the improvement in the results when Pt is added to the cobalt catalyst, and whether Rh is significantly more pronounced than the slight improvement (with or without) with other Group VIII metals,

inactive in the Fisher-Trops process.

As we can see from Figs. 1, 2 and 3, the full effect of the second metal is achieved with relatively small amounts of these metals. Catalyst containing 12 wt. % cobalt, maximum catalytic activity is observed when the weight ratio of the second metal to Co is about 0.01 if the second metal is Pt, Ir or Rh. By the way, the additional amounts of these second metals have almost no effect on full activity. Thus, it is possible to introduce a second metal over a wide dosage range without compromising the substantial increase in lithium activity of catataLT 3622 B achieved with low doses of the second metal.

FIG. Figures 4, 5 and 6 show an improvement in the catalytic activity of the cobalt catalyst, whereby the addition of the second metal changes the amount of Co but maintains the weight ratio of the second metal to Co of 0.0085.

The significant increase in the hydrogenation activity of carbon monoxide when small amounts of Pt, Ir or Rh are added to the cobalt catalyst is apparently unique to the carrier alumina. As can be seen from the test results in Table VI, there is no increase in activity if small amounts of Pt, Ir, or Rh are added to the cobalt deposited on silica or titanium dioxide. It is a hitherto undefined property of alumina that enables the second metals to substantially promote the dispersion of cobalt on this carrier. On silica and titanium, this second metal property, dispersed in Co, does not occur and the catalytic activity remains unchanged. Other inorganic oxides having the same properties as aluminum oxide may also exhibit an increase in activity upon addition of these second metals. Although we do not wish to give a detailed explanation, it is possible that alumina is such an effective carrier of the catalyst according to the present invention because it is linked to the complex dependence of the carrier isoelectric point and the charge of catalytic metal samples in solution. In this way, Pt, Ir, and Rh can be added to Ru and Re, which were previously observed / see. Kobylinski, U.S. Pat. 4,088,671 / and U.S. Patent Application Ser. 113095 / due to a substantial increase in the activity of cobalt / two or more times on an alumina carrier for the synthesis of hydrocarbons. Such substantial increases in activity are not observed for metals other than transition group VIII, except Pd, which is sensitive to the loading dose, which is discussed in the following paragraph. The role of the second metal is apparently that it helps to disperse cobalt better. The second metal properties it apparently needs to increase cobalt dispersion include the ability to readily reduce, form cobalt alloys within the range of concentrations used, the absence of a tendency to aggregate on the cobalt surface, and the ability to interact with the alumina surface to form more crystallization centers for cobalt. Perhaps all effective second metals may be subjected to a number of promotional mechanisms.

An attractive property of Pt, Ir, and Rh as cobalt additions on alumina is that if small amounts of these metals significantly increase the activity of cobalt in the CO hydrogenation reaction, large amounts do not adversely affect the activity and selectivity of the catalyst. FIG. 1-3 /. This behavior, hereinafter referred to as dose-insensitivity, does not persist for all Group VIII metals and even for all precious metals. Thus, for example, although the addition of a limited amount of Pd does not increase the activity of the cobalt catalyst, the bulk additive in the range used for Pt, Ir and Rh reduces the activity of CO hydrogenation much less than that of cobalt on alumina without second metal additives. FIG. 7 /.

Dose insensitivity is a particularly important characteristic for secondary / relative-size aspects / components in industrial catalysts.

Claims (16)

DEFINITION OF INVENTION Catalyst-active catalysts for the conversion of synthesis gas to hydrocarbons containing catalytically active amounts of cobalt for the synthesis of Fisher5 Tropic, characterized in that they contain at least one dose-insensitive second metal selected from the group consisting of platinum, iridium and rhodium deposited on alumina carrier. to obtain a final catalyst containing 10 having a positive X-ray diffraction pattern, and wherein the amount of the second metal indicated is less than that of cobalt. Catalyst according to claim 1, characterized in that the amounts of cobalt are from about 5 to about 60% by weight of the catalyst. 3. Catalyst according to claim 1, characterized in that the amounts of cobalt are from about 20 10 to about 45% by weight of the catalyst. 4. A catalyst according to claim 1, wherein the at least one of the second metals is present in an amount of from about 0.1 to about 25 50% by weight, based on the amount of cobalt in the catalyst. 5. A catalyst as claimed in claim 1, wherein the amount of at least one of the second metals is in the range of about 0.5 to about 30 20% by weight of cobalt in the catalyst. 6. The catalyst of claim 1, wherein said carrier is gamma potassium oxide. 7. The catalyst of claim 1, wherein said carrier has a surface area of at least about 100 m ³ / g and a pore volume of at least about 0.3 cm ³ / g. 8. The catalyst of claim 1, further comprising a promoter in an amount of from about 0.1 to about 5% by weight of the catalyst selected from the group consisting of metal oxide elements selected from Periodic Table IIIB, IVB, and VB. groups. 9. The catalyst of claim 1, wherein said diffraction pattern has peaks in the range 2Q from 65 to 70 degrees, wherein Q is the refraction angle. 10. A catalyst for the conversion of a synthesis gas to a hydrocarbon containing a cobalt and a second metal selected from the group consisting of platinum, iridium, rhodium and mixtures thereof, deposited on a support - alumina, to obtain a final catalyst having a positive X-ray diffraction pattern; and wherein the cobalt is present in catalytically active amounts up to about 60% by weight of the catalyst, and the catalyst of said second metal has relatively lower amounts than the cobalt in the range that allows for increased cobalt activity. 11. The catalyst of claim 10, wherein the amount of said second metal is in the range of about 0.1 to about 50 weight percent of the amount of cobalt in the catalyst. 12. A catalyst according to claim 10, comprising an effective amount of a promoter selected from the group consisting of metal oxide elements selected from the periodic table. Groups IIIB, IVB, VB, lanthanides, actinides, MgO, MnO and mixtures thereof. 13. The catalyst of claim 10, wherein the amount of said promoter is in the range of about 0.1 to about 5% by weight of the catalyst. 14. The catalyst of claim 10, wherein said carrier has a surface area of at least about 100 m / g and a pore volume of at least about 0.3 cn / g. 15. The catalyst of claim 10, wherein the amount of elements adversely affecting the alumina carrier is maintained below 100 parts per million. 16. The catalyst of claim 10, wherein said X-ray diffraction pattern has peaks in the range 2Q from 65 to 70 degrees, wherein Q is the refraction angle. FIG.