DE2712909A1 - METHOD OF SYNTHESIS OF HYDROCARBONS - Google Patents

Description

Process for the synthesis of hydrocarbons

The invention relates to processes for the synthesis of various hydrocarbons from hydrogen and carbon monoxide using ruthenium, nickel or rhodium applied to titanium-containing oxides as a catalyst.

In 1938 Pichler (see H. Pichler, Fuel-Chem. 19: 226 (1938); H. Pichler and H. Buffleb, Fuel-Chem. 21, 247, 273, 285 (1940)) found that using of ruthenium as a catalyst from hydrogen and carbon monoxide at low temperatures and very high pressures high molecular weight Paraffin waxes can be obtained. Because ruthenium is such a particularly good hydrogenation catalyst, is side ability, catalyzing the synthesis of olefins has not been noticed. This follows from the only, under typical Synthesis conditions carried out investigation in which

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Ruthenium applied to a carrier at a pressure of 2160 kPa and a temperature of 220 to 240 ° C and at H ₂ / CO ratios of 1 to 3 was used. It was found that the hydrocarbon products contained only small amounts of olefins (see FS Kam et al, I&EC Product Res. & Devel. 4, 265 (1965)). With an H./CO ratio of 1, more than 85% by weight of the hydrocarbon product consisted of C ₅ material. At a pressure of 100 kPa and a temperature of 222 C, however, only methane was observed as the only hydrocarbon product. It is clear that, accordingly, using typical ruthenium catalysts, one would expect that at moderate pressures mainly high molecular weight paraffins and at atmospheric pressure mainly methane would be obtained.

Since ruthenium is so expensive, industrial synthesis methods come in only supported, highly dispersed ruthenium catalysts considered because it is only in this state that the catalytic activity of most, if not all, of the ruthenium atoms can be exploited. It is therefore necessary to prepare these catalysts in such a way that they have a have a large ruthenium surface, which at the same time has the required ruthenium load for the desired activity is decreased. Since it is now possible to manufacture catalysts in this way, they can be considered serious Candidates for technical synthesis processes of olefins and paraffins from CO and H_ should be considered.

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The subject of the invention is accordingly, inter alia, a new process for the selective synthesis of olefinic hydrocarbons and in particular olefins with a chain length of C- to C ₁₀ from CO and H "at pressures of 100 to 3100 kPa, which is characterized in that a CO and H "-containing synthesis gas with an H" / CO ratio of 0.1 to 10, preferably 0.5 to 4 and in particular 1 to 3 with a space flow rate of 100 h to 50,000 h passes over a catalyst for a sufficient period of time which is 0, 01 to 15 wt.% Ruthenium on TiOp, other titanium-containing oxides or mixtures thereof, the desired olefinic hydrocarbon products at a temperature of 100 to 500 ⁰ C, preferably 150 to 400 ° C and in particular 150 to 300 ⁰ C and a Pressure of 100 to 10 kPa (1 to 10000 atmospheres), preferably 100 to 3100 kPa, and especially 100 to 2060 kPa. The ruthenium catalyst system used according to the invention and applied to a carrier has a total BET surface area of 10 to 60 mg with ruthenium
less than 5 nm (50 A).

60 mg with a ruthenium crystallite size of preferably

Ruthenium applied to TiO ₂ , other titanium-containing oxides, or mixtures of titanium oxides is a catalyst system that exhibits superior properties in terms of the synthesis of hydrocarbons in synthetic processes.

The titanium-containing oxide supports which can be used according to the invention

2-1 are oxides with surface areas of 1 to 200 m g, preferably

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• Γ

2-1 2-1

10 to 100 mg and especially 25 to 100 mg. Suitable oxides include TiO ₃ , Al ₂ O ₃ -TiO ₃₇ SiO ₃ -TiO ₃ , Ti0 ₂ carbon, ZrTiO ₄ , alkaline earth titanates (BaTiO ₃ , CaTiO ₃ , SiTiO ₃ , MgTiO ₃ ), alkali titanates (Na ₃ TiO ₃ , Li ₃ TiO ₃ , K ₃ TiO ₃ ) and rare earth titanates. The titanium oxide TiO ₃ is preferred. In the case of most metal catalysts applied to a carrier, the greater the surface area of the carrier, the greater the dispersion of the metal for a given metal loading. It is therefore desirable to use a TiO ₂ with as large a surface area as possible in order to maximize the dispersion of the ruthenium metal. However, if you work with TiO-, which has a surface area of 150 to

2 - 1
250 mg (usually produced by the precipitation process), the surface area is reduced to _{about 500 ° C. when heated. Commercially available TiO 2} , which is produced by flame hydrolysis of TiCl ₄ , has a surface which is stable for thermal treatments at temperatures of about 500 ° C. from

about 60 mg and is therefore the preferred carrier used. For thermal treatments at temperatures below 500 ^° _{C., TiO 2} produced by precipitation processes can be used successfully. The ruthenium is deposited on the selected support in a concentration of 0.01 to 15% by weight, preferably 0.1 to 10% by weight and in particular 0.5 to 5% by weight, the ruthenium having a crystallite size of 1 to 20 nm, preferably 1 to 10 nm and in particular 1 to 5 nm. The crystallite size is determined using standard methods such as X-ray diffraction or transmission electron microscopy.

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Using standard experimental procedures on a ruthenium / TiO ₂ system that has been reduced with hydrogen at 450 ° C., X-ray diffraction shows no ruthenium particles in the reduced catalyst, indicating that the ruthenium particles have crystallite sizes of less than 5 nm, corresponding to a degree of dispersion of own more than 20%.

Ruthenium catalysts applied to TiO ₂ , other titanium-containing oxides or mixtures thereof show selectivity for olefin products and in particular C ₂ ~ C ₁₀ olefins. When used according to the invention, these catalysts show an improved selectivity with regard to the olefins mentioned, an improved service life and insensitivity to sulfur as well as a greater resistance to the volatilization of ruthenium in oxidizing atmospheres compared to known ruthenium catalysts which are based on materials such as Al ₃ O ₃ , SiO_ or carbon are applied.

The ruthenium catalysts used according to the invention are produced by processes known for the production of other catalyst systems such as Ru on Al ₂ O. A suitable ruthenium salt such as ruthenium chloride, ruthenium nitrate or ruthenium acetate is dissolved in a solvent such as water or any other suitable solvent and stirred with the selected titanium oxide system. The preferred carrier is TiO ₂ , which has been produced by flame hydrolysis of TiCl ₄

2-1 and has a surface area of about 60 m g. After founding

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Lichem mixing the mixture is allowed to dry and then subjecting them to a heat treatment in air at a temperature of 100 to 15O ° C or is dried immediately by heating for several hours in air to a temperature of 100 to 150 ⁰ C.

The final step in the preparation is essential, in which the supported ruthenium catalyst, which has been prepared as described above or by similar processes, is heat treated in a reducing atmosphere such as hydrogen for 0.5 to 4 hours and preferably 1 to 2 hours at a temperature of more than 300 ° C, preferably more than 400 ° C and in particular more than 500 ⁰ C is subjected.

Nickel applied to TiO, other titanium-containing oxides or mixtures of various above-mentioned titanium oxides represents a catalyst system which also shows superior properties in the synthesis of hydrocarbons. A nickel catalyst applied to such a support shows selectivity for paraffinic C ₂ -C ₇ -hydrocarbon products which are free from olefins and oxygen-laden products. They give CO conversions of up to 60% at pressures of 3090 kPa without a significant change in product composition. A large fraction of the product obtained contains 2 or more carbon atoms in the chain with conversions of up to 60%. The nickel catalyst applied to the said supports

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possesses increased activity, improved selectivity for high molecular weight normal paraffins, improved service life and Insensitivity to sulfur and greater resistance to the formation of nickel carbonyl compared to nickel catalysts on other supports such as Al ~ O ,, Silicon oxide or carbon.

Conventional nickel catalysts such as Ni / Al-O, and Ni / SiO ~ are known for their selectivity for methane formation (cf. e.g. M. Greyson, "Catalysis", Vol. IV, 473 (1956) and H.A. Dirksen and H.R. Linden, Research Bulletin No. 31, Institute of Gas Technology (1963)). In a wide range of temperature, Pressure and H ~ / CO ratio, methane is by far the main product, and because of this, nickel is the catalyst of choice for industrial methane syntheses from CO and H2.

Nickel has been dispersed on and co-precipitated with a variety of typical oxide supports, but there have been no significant effects on product distribution were observed. If higher hydrocarbons have been observed are these usually gaseous materials, consisting mainly of ethane and only small amounts of C, hydrocarbons. The effects of a large number of promoters on the activity and selectivity of nickel catalysts has been studied and it has been found that ThO- is the only material that has a pronounced influence on the product composition Has. Usually used with Ni / kieselguhr catalysts

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det, the addition of 12 to 24 parts of ThO ₂ per 100 parts of nickel, based on the total hydrocarbon products ^{, results in up to 60 to 70% by weight of C, - +} material including solid and liquid products (see RB Anderson, "Catalysis", Vol. IV, 53 (1956)). No other promoters are known which would be able to effect such a change in product selectivity. Although the catalyst activity was increased somewhat by the addition of ThO-, these increases in activity were not large and were usually up to 10%.

For the reasons mentioned, nickel catalysts have often been used in the past for the synthesis of methane from CO and H ₂ , since they have a very good selectivity with regard to this product. With the exception of the catalysts containing ThO ₂ as a promoter, the nickel catalysts were not known to have the ability to produce large amounts of higher molecular weight products. The inventive dispersion of nickel on TiO ₂ or a support containing Ti changes the catalytic behavior of nickel, which leads to a catalyst which gives a product with a very much higher average molecular weight. In addition, the very desirable effect of improving the activity of the nickel component is achieved.

The invention thus furthermore relates to a process for the selective synthesis of _{relatively high molecular weight normal paraffins from CO and H 2} over a wide range of CO conversions at pressures

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from 103 to 3090 kPa, which is characterized in that one
a synthesis gas containing CO and H 2 with an H_ / CO ratio of 0.1 to 10, preferably 0.5 to 4 and in particular 1
to 3 with a space velocity of 100 h to
50,000 hours passed over a catalyst containing 0.01 to 75 wt
500 ⁰ C, preferably 150 to 400 ⁰ C and in particular 150 to
300 C and a pressure of 103 to 1.03 χ 10 kPa, preferably
103 to 3090 kPa and in particular 103 to 2060 kPa.

The nickel catalysts applied to the supports mentioned

2 -1
have a total BET surface area of 10 to 60 mg

a nickel crystallite size of preferably less than 10 mm
(100 8) (measured by X-ray diffraction). Suitable size ranges are 1 to 30 nm, preferably 1 to 10 nm and in particular 1 to 7.5 nm.

When using standard test methods, a 10% Ni / Ti0 ₂ catalyst reduced with hydrogen at 450 C shows in the case of the
X-ray diffraction corresponds to a crystallite size of 7.5 nm
a nickel dispersion level of about 14%. For a 1.5% Ni / TiO system, the particle size is less than 5 nm, since Ni metal could not be detected with the aid of X-ray diffraction. This corresponds to a degree of dispersion of more than 20%.

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The nickel catalysts used according to the invention are prepared by processes similar to those described above for ruthenium.

A Ni / Ti0 ₂ ~ supported catalyst can also be produced by reducing the compound NiTiO _{3 , which converts into metallic nickel on TiO 2} upon reduction with hydrogen at a temperature of about 450 ° C. The reduction of the stoichiometric NiTiO ₃ to Ni / TiO »results in a catalyst with 38% by weight of Ni on TiO.

The final stage of the manufacturing process, heat treatment, proceeds as described above for the supported ruthenium catalyst.

The process according to the invention selectively yields C_ normal paraffins from CO and H ₂ when using the nickel catalyst system described above, provided that a temperature below 50O ⁰ C is used. The use of the catalyst described also allows the syntheses to be carried out at lower temperatures than previously known, with corresponding product yields and CO conversion rates being obtained. These superior results are obtained when using catalysts which have nickel loadings corresponding to the known catalysts.

Rhodium catalysts for the production of higher molecular weight hydrocarbons from CO and H ~ are only being investigated of the "Bureau of Mines" (J.F. Schultz et al,

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-Pf-

US Bureau of Mines Report No. 6974, 1967). This investigation showed that rhodium applied to Al-O. Gives 95+ wt.% Methane at typical H ₂ / CO ratios, a pressure of 2163 kPa and temperatures of 440 to 58O ° C. Because of its high price and low activity compared to other metals, rhodium has been reported to be unattractive as a catalyst for methane production.

It has now been found, however, that rhodium dispersed on TiO or other supports containing titanium oxide described above has a high activity and changed selectivity. Compared with rhodium applied to Al-O ^, the use of the _{metal applied to TiO 2} or titanium-containing oxides in olefin synthesis processes leads to a process which yields considerably smaller amounts of methane and correspondingly larger amounts of higher molecular weight paraffins and olefins.

The invention therefore furthermore relates to a process for the synthesis of olefinic hydrocarbons, in particular C ₂ -C _t -olefins and especially C 1 -C hydrocarbons from CO and H ₂ , which is characterized in that a CO and H ₂ containing synthesis gas with an H ₂ / CO ratio of 0.1 to 10, preferably 0.5 to 4 and in particular 1 to 3 with a space flow rate of 100 h to 50,000 h passes over a catalyst that is 0.01 to 10 wt.% Rhodium on TiO ₂ , other titanium-containing oxides or mixtures thereof, and so the formation of the desired

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-U-

brings about olefinic hydrocarbon products in the desired ratio, the contacting at a temperature of 100 to 500 ° C, preferably 150 to 400 ° C and in particular 150 to 3OO ⁰ C and a pressure of 100 to 10 kPa, preferably 100 to 3000 kPa and in particular 100 to 2000 kPa. The rhodium catalyst system applied to the supports mentioned has a total BET surface area of 10 to

2 -1

60 mg with a rhodium crystallite size of preferably less than 5 nm.

The rhodium is applied to the selected carrier in a concentration of 0.01 to 10% by weight, preferably 0.05 to 5% by weight and in particular 0.1 to 2 wt.% Applied, the rhodium having a crystallite size of 1 to 20 nm, preferably 1 to 10 nm and in particular has 1 to 5 nm. The crystallite size was determined using standard methods such as X-ray diffraction or transmission electron microscopy.

Using standard experimental procedures gives the X-ray diffraction in the case of a rhodium / TiO system reduced with hydrogen at 450 ° C., no rhodium particles in the reduced catalyst, which indicates that the rhodium crystallites have an average size of less than 5 nm, corresponding to a degree of dispersion of own more than 20%.

The rhodium catalysts used according to the invention are in in a corresponding manner as described above for ruthenium.

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Also the last process step, the heat treatment, at The manufacturing process is as described for the ruthenium catalyst.

The use of the above-described catalyst in the invention Process under reaction conditions corresponding to those of known processes gives superior results in terms of improved selectivity and greater product yield when using catalysts, their Rhodium loading corresponds to that of known catalysts.

example 1

Ruthenium catalysts with improved selectivity for olefin products and hydrocarbons with a carbon chain length of 2 to 10 carbons are obtained by applying ruthenium to oxide supports containing TiO "or titanium. Accordingly, a 2% Ru / TiO_ catalyst is prepared by adding 10 g of TiO ₂ and 3 ml of a RuCl., Solution containing 0.2 g of ruthenium, stirred together. The TiO- is made by flame hydrolysis of TiCl. manufactured to give the wearer a surface

2 -1
of 60 mg. Titanium oxide produced by other methods such as precipitation and calcination of a suitable salt can also be used satisfactorily. After thorough mixing of the TiO ₂ and the ruthenium solution, the mixture is dried in air at 110 to 120 ° C. overnight.

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-Vi-

To demonstrate the desired properties of the Ru / TiO catalysts, they were applied to conventional supports such as Al ₃ O ₃ or carbon compared with ruthenium. Accordingly, a 5% ruthenium / Tj -Al ^ O- ^ - catalyst was prepared by thoroughly mixing _{5.26 ml of a RuCl 3} solution containing 0.526 g ruthenium with 10 g ^ -Al ₃ O _3. The resulting mixture was air dried at 110 to 120 ° C overnight. A 4% Ru / carbon catalyst was prepared by adding 6 ml of a RuCl-j solution containing 0.12 g of ruthenium to 3 g of carbon with a surface

2 -1
of about 100 mg were thoroughly mixed. The resulting mixture was dried in the air at 110 to 120 ^{° C. overnight.}

The desirable selectivity properties of ruthenium catalysts applied to TiO or titanium-containing oxide supports in comparison with other supports can be seen from the data in Tables 1, 2 and 3. At a total pressure of 103 kPa, Ru / TiO _? a significantly different product composition than Ru / Al_0 ,. The formation of methane and very high molecular weight hydrocarbons is suppressed in the case of the Ru / TiO_ catalysts, and a product composition is obtained in which the carbon chain length is maximized in the range from 2 to 5 carbon atoms. With Ru / Al_0, much more methane and higher molecular weight hydrocarbons are produced. Ru / TiO_ also has the desirable property that a large proportion of the C ₂ -C ₅ -PrO products are olefinic in nature. Accordingly, this catalog is

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-W-

lysator particularly suitable for the production of a product stream from CO and H ₂ , which is largely olefinic and whose components have carbon chain lengths of 2 to 5 carbon atoms. Olefins such as ethylene, propylene, butenes and pentenes are particularly desirable in this area as chemical intermediates for the production of plastics, rubber, alcohols, ketones and aldehydes as well as esters and acids.

Table 2 shows the good selectivity _{properties of ruthenium catalysts applied to TiO 2} or titanium-containing oxide supports at higher total reactant pressures. At a pressure of 10 kPa, Ru / TiO ₂ yields less methane and C "hydrocarbons than Ru / Al ^ O. ,, whereby most products when using Ru / TiO _{2 are} in a carbon number range from C ₂ to C ₇ . Ru / TiO »thus has an improved selectivity with regard to the desired ^ - ^ - hydrocarbons. Table 2 also shows the improved selectivity for olefins of Ru / TiO_ compared to Ru / Al ₂ 0 ,. In the area of C ₃ -C ₁ products, 42% of the products are _{olefins when using Ru / TiO 2} , while only 25% are olefins when using RuZAl ₃ O _3. Ru / TiO “is therefore more selective for the production of the desired olefins with carbon chain lengths of 2 to 5 carbon atoms.

In Table 3, Ru / TiO _{2 is} compared to ruthenium on several other supports. Ruthenium on TiO or other titanium-containing oxide supports yields 42% by weight of products with carbon chain

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ten lengths of 2 to 5 carbon atoms, while ruthenium on Al ₃ O ₃ , carbon or ruthenium metal gives 31%, 2% and 25% products in this carbon number range, respectively. In addition, the proportion of olefins in the products is greatest with Ru / TiO-, which results from the ethylene / ethane ratios of the catalysts. Ruthenium on Al-O, or carbon or ruthenium metal used without a support result in little or no ethylene in the C ₂ fraction in the synthesis from CO and H ₂ under the reaction conditions given in Table 3, while Ru / TiO-about half of the C_ Fraction yields ethylene.

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Tabel

Selectivity of ruthenium catalysts (reaction conditions: H_ / CO = 1, pressure: = 103 kPa)

catalyst

(a)

CD
CX)

% Ru / TiO

Temp. ( ⁰ C)

262

% CO conversion

0.7

product
Carbon number

Total weight%

% By weight of olefins

12th

20th

15th

% By weight paraffins

5 8 4 3

267

1.7

K)

-J

Kl

co

(a) Each catalyst was reduced for 1 hour at 450 C before the feed at de Reaction temperature was fed.

Tabel

Selectivity of ruthenium catalysts (reaction conditions: H ₂ / CO = 1, pressure = 980 kPa)

catalyst

(a)

2% Ru / TiO

% CO conversion

267

product
Carbon number

Total
Weight%

Weight%
Olefins

14th

16

10

% By weight paraffins

4 7 4 7 5 4

5%

274

10

24 —— - 6th 1 5 16 12th 4th 11 6th 5 12th 6th 6th 1 1 - - 9 - - 12th —— _

- ro

K)

CO

CO

(a) Each catalyst was reduced for 1 hour at 450 ° C before the feed at the Reaction temperature was fed.

Table 3

Selectivity of ruthenium catalysts (reaction conditions: H ₃ / CO = 3, pressure = 103 kPa)

Product mole%

catalyst Temp. % CO CH ^C 2 ^H 4 CpH, ^C 3 ^H 6 ^C 4 ^H 8 ^C 5 ^H 10 ^C 6 ( ⁰ C) conversion 54 6th 5 C, H _a ^C 4 ^H 10 ^C S ^H 12 4th 2% RuTiO ₂ ^(a) 228 1.8 66 1 9 16 10 ~ J I t »
5 4th -J 5% Ru / Al _o 0 ^ ^a)
O ^{2 3} 229 10.6 98 0 2 6th 9 6th 0, ■ ^ 4% Ru / CoalA- ⁾ 234 1.6 0 0 0 * ° ί ^ fabric 74 0 13th 1 ' ' ■ ». Ru metal ^c ' 217 27.1 8th 3 1 ο powder

(a) Catalysts were reduced at 450 ° C for 1 hour before feeding the feed became.

(b) The catalyst was reduced at 400 ° C for 1 hour before feeding the feed became.

(c) The catalyst was reduced at 300 ° C for 1 hour before feeding the feed became.

Example 2

Catalysts with improved activity and selectivity for normal paraffin products with carbon chain _{lengths of 2 and more carbon atoms are obtained by applying nickel to TiO 2} or other titanium-containing oxide supports. Accordingly, a 1.5% Ni / Ti0 ₂ catalyst is prepared by stirring 11.4 ml of a 0.39 g nickel-containing nickel nitrate solution with 25 g TiO- in a beaker. The TiO- was obtained by flame hydrolysis of TiCl. manufactured and owned one

2 -1

Surface of 60 m g. By other methods such as precipitation Titanium oxide prepared and calcining a suitable titanium salt can also be used satisfactorily will. After thoroughly mixing the nickel solution with the TiO2, the resulting material is placed in a desiccator overnight dried and also further dried in the air in an oven at 120 ° C. overnight. Alternatively, the resulting Material must be air-dried immediately at 120 ° C for several hours. A 10% Ni / TiO catalyst is made, by mixing 20 g of TiO- with 11.1 g of NiNO-.6H-0, dissolved in 5 ml of distilled Water, mixed in a beaker with a spatula. The resulting material is in a desiccator overnight dried and also further dried in air at 120 ° C. overnight. By impregnating the dried 10% Ni / TiO catalyst with additional amounts of nickel nitrate solution, concentrations of Ni on TiO- of up to about 75 wt.% can be obtained.

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In order to demonstrate the advantageous properties of the Ni / TiO_ catalysts, they were compared with several commercially available nickel catalysts and several nickel catalysts on Al ₃ O ₃ and SiO ₂ . A 5% Ni / ^ -Al-O ^ catalyst was prepared by thoroughly mixing 9.5 g of to -Al “0, with a surface area of 245 mg, with 6.6 ml of a nickel nitrate solution containing 0.5 g of nickel became. The resulting mixture was dried overnight at 11O ⁰ C in air. A 16.7% Ni / SiO_ catalyst was prepared by adding 10 g SiIi-

2 -1 cium oxide with a surface area of 300 mg were thoroughly mixed with 20 ml of a nickel nitrate solution containing 2 g of nickel. The resulting material was dried in the air at 110 ^{° C. overnight.}

A number of supported nickel catalysts and pure nickel oxide catalysts were reduced at 450 ° C for 1 hour before a CO-H _? Feed material was carried out at a temperature of 205 ° C. The increased activity of the _{nickel catalysts applied to TiO 3} compared with several other nickel catalysts is shown in Table 4. The 10% Ni / TiO_ catalyst is, based on 1 g of catalyst, much more active than other nickel catalysts that contain much larger amounts of nickel.

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Table 4
Activities of nickel catalysts for the CO-H ₂ reaction

(CO-H ₂ reaction conditions: 2O5 ° C, 103 kPa, H- / CO = 3)

Catalyst, u moles of CO converted /, u moles of CO converted /

Second / g nickel second / g catalyst

5 % Ni / «J-Al ₂ O ₃ % Ni / TiO ₂ 3.44 0.172 8th, 8% Ni / * 7-Al ₂ O ₃ 53% Ni / TiO- 1.63 0.143 42 % Ni / oL-Al ₂ O ₃ 0.21 0.088 16 % Ni / SiO ₂ 2.36 0.394 20th % Ni / graphite 0.064 0.082 pure Ni metal 0.032 0.032 10 22.8 2.28 1, 8.35 0.113

(a) All catalysts were 1 hour before the activity test

reduced at 450 ° C.

Nickel catalysts applied to oxide supports containing TiO ₂ or titanium also show desirable selectivity properties compared with pure nickel or nickel on SiO ₃ or Al ₃ O _3. This is shown in Table 5. Nickel on several carriers, eg Al ₃ O ₃ , SiO ₃ , graphite and pure nickel, almost exclusively produces methane with only small amounts of hydrocarbons with a carbon chain _{length of up to 4. The nickel catalysts applied to TiO 3} or titanium containing oxide carriers

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- 33 -

result in a considerable reduction in the methane content and an increase in paraffin products with carbon chain lengths of 2 carbon atoms and more. This is particularly desirable for the production of storable liquid fuels from CO-H ₂ mixtures that are obtained from coal gasification.

The increased selectivity of on TiO _? Nickel catalysts applied or titanium-containing oxide carriers are retained over a conversion range of up to about 50%, as can be seen in FIG. Nickel catalysts with other supports, on the other hand, show a much poorer selectivity for high molecular weight paraffins than metal catalysts applied to oxide supports containing TiO or titanium.

The selectivity of oxide supports containing TiO_ or titanium applied nickel catalysts for hydrocarbons with carbon chain lengths of 2 and more remains even at higher Pressures obtained compared to nickel on other carriers. This is shown in Table 6. The behavior of the Ni / TiO catalysts as a function of pressure for the production of higher molecular weight paraffins is opposite to that of Ni / Al-O.,. As Table 6 shows, it is most advantageous to use the Ni / TiO catalysts to be used at low pressures to maximize the production of higher molecular weight paraffins while when using Ni / Al ^ O., high pressures are required. this is an advantageous property of containing on TiO or titanium Oxide supports applied nickel catalysts, there

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no compression of the synthesis gas is required to operate a gasification liquid fuel synthesis plant and to maximize the production of the desired liquid paraffins.

Example 3

The advantages of _{nickel catalysts applied to TiO 2} or titanium-containing oxide supports with regard to suppressing the formation of nickel carbonyl in the presence of CO were demonstrated with the aid of infrared spectroscopy. It is known that nickel reacts with carbon monoxide to form volatile nickel carbonyl Ni (CO) ₄ , which can lead to a loss of nickel and the appearance of a toxic product, namely Ni (CO) ₄ , which escapes from the reactor. The formation of Ni (CO) ₄ is suppressed in nickel catalysts applied to TiO or titanium-containing oxide supports compared to nickel on other supports such as Al ₃ O ₃ , ^s * -®2 ^{un (} * graphite.

The rate of formation of Ni (CO) ₄ with a 10% Ni / TiO_ catalyst was compared to that with a 10% Ni / SiO catalyst. The 10% Ni / Si0 ₂ ~ catalyst was produced

2 -1 by adding 10 g SiO- with a surface area of 300 m g with 22 ml a solution of nickel nitrate containing 1.11 g of nickel were mixed. The resulting material was air dried at 120 ° C overnight.

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The 10% Ni / TiC ^ - and the 10% Ni / Si0 ₂ catalyst were pressed into thin disks weighing 27 to 29 mg in separate experiments and placed in a cell that was designed with that of DJC Yates, WF Taylor and JH Sinfelt in J. Am. Chem. Soc, 86, 2996 (1964) was identical. The air was pumped out of the cell and a hydrogen flow of 12 l / h was introduced. The cell was then rotated so that the disk came to rest on the silicon oxide end of the cell, which was then placed in an oven. The discs were reduced for 1 hour at 50O ⁰ C with hydrogen and then evacuated at the same temperature for removing hydrogen for 10 minutes. The disks were then cooled to room temperature in vacuo and the cell rotated so that the infrared windows were in the spectrometer beam. In these experiments, the disks were kept out of the infrared beam, so that the formation of Ni (CO) . could be followed in the gas phase with the help of infrared spectroscopy.

CO was added to each catalyst under a pressure of 1.87 kPa and the concentration of Ni (CO) ₄ in the gas phase due to the reaction of CO with the nickel of the catalysts was followed as a function of time. Figure 2 shows a graph of the optical density of Ni (CO)., Which is proportional to the concentration of Ni (CO). is in the gas phase around the catalyst as a function of time. As can be seen from the graph, the 10% Ni / Ti0 ₂ catalyst is in terms of the formation of Ni (CO). much less reactive than nickel on SiO ₂ . The on

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TiO and titanium containing oxide supports applied nickel catalysts thus have the advantageous property of forming Ni (CO). to inhibit.

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Table 5

O
UD
OO

catalyst

% Ni / TiO ₂
1.5% Ni / TiO,

pure Ni

42

_ »8.8% Ni / 7 -1
O 5%

- ¹ 16.7% Ni / SiO_
% Ni / graphite

Temp. C

243 251 252 236 230 254 220 234

Selectivity of Nickel Catalysts = 3 MoI. ^
with the
fi \ Paraffin
Carbon number C ₄ P = 103 kPa, H ₂ / CO C ₁ 9 25th 8th % CO conversion 50 14th 12th 8th 24 58 6th - - 13.3 94 14th 5 3 7.9 76 14th 3 2 2.1 81 7th 3 1 3.1 90 5 3 1 10.8 92 7th 4th 1 3.3 87 24.8

9 7

¹ , ' 3

CD O CD

Table 6

Selectivity of nickel catalysts at different pressures

(Reaction conditions: H ₂ / CO = 3, temp. = 2OO-2O6 ° C)

catalyst Pressure (ATM) % CO conversion C ₁ 5 MoI.
^C 2 C. product
3 C. 4th < 10% Ni / TiO ₂ 1
10 4th
3.5 50,
56 5 21, 5
37 7th
5 , 5
, 5 7th
1 , 5
, 5 12th 20th 4.5 57, 35 5 , 5 2 - 31.4% Ni / oC-Al ₂ O ₃ 1 2.1 80 16 4th 1 - 10 1.9 69 29 2 - - - 20th 1.3 69 31 _ _ _ _ __

ATM = 103 kPa

CO CD CD

Example 4

Rhodium catalysts with improved selectivity for hydrocarbons with carbon chain lengths of 2 to 5 carbon atoms and improved selectivity for olefinic hydrocarbons in this carbon number range are obtained by applying rhodium to TiO or other titanium-containing oxide supports. A 2% by weight Rh / TiO ^ catalyst is prepared by _{stirring 20 g of TiO 2} with 4.08 ml of a RhCl, solution containing 0.408 g of rhodium. The TiO- was obtained by flame hydrolysis of TiCl. produced and had a surface area of 60 mg. Titanium oxide produced by other methods such as precipitation and calcination of a suitable salt can also be used satisfactorily. After thorough mixing of the TiO and the rhodium, the mixture at 120 ⁰ C overnight was air dried.

In order to demonstrate the advantageous properties of the Rh / TiO_ catalyst, it was compared with rhodium dispersed _{on Al 3} O _3. A 2% Rh / Al ~ 0 -.- catalyst was prepared by adding 5 g of Al_0_. were mixed with 3.52 ml of a RhCl, solution containing 0.102 g of rhodium. The resulting mixture was air-dried ^{at 110 to 120 ° C. overnight.}

Table 7 shows the advantageous properties of rhodium catalysts applied to oxide supports containing _{TiO 3 or titanium.} Rhodium on TiO »gives an improved selectivity for hydrocarbons with carbon chain lengths from 2 to

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5 carbon atoms for all H./CO ratios. Thus, with an H ₂ / CO ratio of 1.6, 26 mol% of the products are C ₃ -C ₅ hydrocarbons, while Rh / Al ^ O only gives 14 mol% hydrocarbons in this carbon number range. In comparison to Rh / Al-O, Rh / TiO ^ also has an increased selectivity for olefins. As Table 7 shows, is the ratio of ethylene to ethane under all conditions for Rh / TiO- greater than for Rh / A1 _? Ot. Rh / TiO_ thus has the advantageous properties of improved selectivity for C ^ -C ^ hydrocarbons and olefins. These hydrocarbons are in great demand as chemical intermediates for the manufacture of plastics, rubber, alcohols, ketones, aldehydes, esters and acids.

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Table 7

catalyst

(a)

■ «4
O
CO
OO

% Rh / TiO,

%

Selectivity of rhodium catalysts (reaction conditions: pressure = 100 kPa)

Temp.
( ⁰ C)

248

265

% CO conversion

0.3 1.3 3.3

5.3

1.6

3.5

5.2

13.9

Mole% product

^H 2 6th CH ₄ C ₂ H ₄ ^C 2 ^H 6 ^C 3 ^H 8 4 ^H 8 C ⁵ S ¹⁰ CO 6th O, O 63 7th O 19th 12th O 1, O 74. 3 2 14th 5 1 3, 6th 80 2 3 1 1 3 2 6, 6th 86 1 4th 7th 2 1 O, O 74 2 14th 6th 3 1 1, O 85 O 10 3 1 O 3, 90 O 8th 2 1 O 6, 93 O 5 2 1 O

O O O O

O O O O

(a) Each catalyst was reduced for 1 hour at 450 ° C before the feed at the Reaction temperature was fed.

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Claims (11)

Claims U. Process for the synthesis of hydrocarbons in which H ₂ and CO are passed over a catalyst for a sufficiently long time at a suitable temperature and pressure, characterized in that the catalyst used is ruthenium, nickel or rhodium applied to an oxide containing titanium. 2. The method according to claim 1, characterized in that one H ₃ and CO in a ratio of 0.1 to 10 with a space flow rate of up to 50,000 V / V / h and at a temperature of 100 to 500 ° C, a A pressure of 100 to 10 kPa is passed over a ruthenium, nickel or rhodium catalyst applied to a titanium-containing oxide carrier for a sufficiently long time, and thus causes the formation of the desired hydrocarbon products in the desired ratio. 3. The method according to claim 1 or 2, characterized in that the titanium-containing oxide is TiO ₃ , ZrTiO., TiO ₂ carbon, TiO ₂ -Al ₂ O ₃ , TiO ₃ -SiO ₂ , alkaline earth titanate, alkali titanates and / or rare earth titanates used. 4. The method according to claim 1 to 3, characterized in that there is used as the titanium-containing oxide TiO-. 709841/0712 ORIGINAL INSPECTED • κ »· 5. The method according to claim 1 to 4, characterized in that there is a titanium-containing oxide with a surface 2 - 1 used from 1 to 200 m g. 6. The method according to claim 4, characterized in that 2 -1 you get a TiO ₂ with a surface area of 25 to 100 mg used. 7. The method according to claim 1 to 6, characterized in that there is a ruthenium on a titanium-containing oxide containing catalyst with a ruthenium concentration of 0.01 to 15 wt.% And a ruthenium crystallite size from 1 to 20 nm are used. 8. The method according to claim 1 to 7, characterized in that one containing an oxide containing ruthenium on titanium Catalyst with a surface area of 10 to 60 2 -1
mg used. 9. The method according to claim 1 to 6, characterized in that there is a nickel on a titanium-containing oxide containing catalyst with a nickel concentration of 0.01 to 75% by weight and a nickel crystallite size of 1 to 30 nm used. 10. The method according to claim 1 to 6, characterized in that there is a rhodium on a titanium-containing oxide 709841/0712 -M- containing catalyst with a concentration of rhodium of 0.01 to 10% by weight and a rhodium crystallite size of 1 to 20 nm are used. 11. The method according to claim 1, characterized in that there is a ruthenium on a titanium-containing oxide containing catalyst with a ruthenium crystallite size of less than 5 nm, a nickel on a titanium containing oxide containing catalyst with a nickel crystallite size of less than 10 nm or a Rhodium on a titanium-containing oxide containing catalyst with a rhodium crystallite size of less used as 5 nm. ka: bü 709841/0712