CA1089495A

CA1089495A - Process for the preparation of hydrocarbons

Info

Publication number: CA1089495A
Application number: CA287,397A
Authority: CA
Inventors: Henricus M.J. Bijwaard; Swan T. Sie
Original assignee: Shell Canada Ltd
Current assignee: Shell Canada Ltd
Priority date: 1976-11-10
Filing date: 1977-09-23
Publication date: 1980-11-11
Also published as: BE860395A; ZA776649B; FR2370712B1; AU513157B2; GB1548468A; JPS5359604A; NL7612460A; DE2750007C2; DE2750007A1; FR2370712A1; IT1087492B; IN147159B; AU2970877A; JPS6337090B2

Abstract

A B S T R A C T
Process for the preparation of hydrocarbons from carbon monoxide and hydrogen. A catalyst is used comprising 10-17 parts by weight of one or more metals of the iron group per 100 parts by weight of carrier and one or more promoters in a quantity of 1-50% of the quantity of metals of the iron group present on the catalyst. The catalyst is prepared by impregnation. The catalyst has a specific average pore diameter (p) of at most 10,000 nm and a specific average particle diameter (d) of at most 5 mm. The quotient p/d is larger than 2 (p in nm and d in mm).

Description

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- 2 -The invention relates to a process for the preparation of hydrocarbons by catalytic reaction of carbon monoxide with hydrogen.
The preparation of hydrocarbons from a mixture of carbon monoxide and hydrogen by contacting this mixture with a catalyst at elevated temperature and pressure is known in the literature as hydrocarbon synthesis according to Fischer-Tropsch. Catalysts frequent]y employed for this purpose comprise one or more metals of the iron group together with one or more promoters to increase the activity and/or selectivity and sometimes a carrier material such as kieselguhr. The catalysts employed in practice for hydrocarbon synthesis according to Fischer-Tropsch are as a rule prepared by precipitation or by melting. Briefly, the preparation of the catalysts by precipitation is effected by making basic an aqueous `~
solution of a salt of a metal of the iron group to which a salt o~ a promoter and a carrier material may be added, if required, as a result of whlch the catalyst is formed as a precipitate. To this precipitate a promoter and a carrier material may be added. Examples of suitable catalysts for the hydrocarbon synthesis prepared according to the precipitation route, are Fe~Cu/Na/SiO2 catalysts comprising 4.5 parts by weight of copper, 4 parts by weight of sodiux and 20 parts by welght of silicon oxide `''`'~ " ': ~

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per 100 parts by weight of iron, as well as Co/ThO2/~gO/
kieselguhr catalysts comprising 5 parts by weight of thorium oxide, 8 parts by weight of magnesium oxide ` and 100-200 parts by weight of kieselguhr per 100 parts by weight of cobalt. The preparation of the catalysts by melting in the case of, for example, iron catalysts is effected by fusing iron oxide with one or more promoter oxides. Examples of suitable catalysts for hydrocarbon synthesis prepared according to the melting route, are Fe/Al2O3/~2O/CaO catalysts comprising 5 parts by weight of aluminium oxide, 1 part by weight of potassium oxide and 3 parts by weight of calcium oxide per 100 parts by weight of iron.
Both the precipitation route and the melting route are rather unattractive methods for the preparation of the present catalysts, because their reproducibility is low. Besides, the precipitation route is very time- ;
consuming, while the melting route requires much energy.
With respect to the performance of the above-mentioned catalysts when used for hydrocarbon synthesis according to Fischer-Tropsch the following remarks can be made.
The performance of catalysts for hydrocarbon synthesis according to Fischer-Tropsch is ~ssessed in the light of their activity and selectivity which have been defined as follows. The activity of the catalyst is the number of grammes of hydrocarbons pr-duoed per litre of catalys~

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per hour. The selectivity of the catalyst is the weight Or C3~ hydrocarbons produced, calculated as a percentage of the total quantity of hydrocarbons produced. ~or a catalyst for hydrocarbon synthesis according to Fischer-Tropsch both a hi~h activity and a high selectivity are desirable. Of these two parameters the selectivity is considered the more important one. Apart from the above-mentioned disadvantages of the catalysts prepared by precipitation or melting, their catalytic performance -is not very satisfactory either. A characteristic of ~-the catalysts prepared by melting is that in the temperature range of about 300-350G, considered optimal for these `~
catalysts, they exhibit a high activity, but only a moclerate selectivity. Attempts to increase the selectivity of the catalysts prepared by melting to the level of the catalysts obtained by precipitation, by applying ~;
lower temperatures, as well as attempts to increase the activity of the catalysts prepared by precipitation to the level of the catalysts obtained by melting, ~;
by applying higher temperatures, have remained unsuccessful.
It is true that these measures can bring about an improvement of the property in question3 but this is accompanied ~ ;
by such a deterioration of the other major property of the catalyst that this other property has fallen below the minimum allowable level for this property `
long before the first property has reached the desired :.:
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In view of the increasing interest in hydrocarbon synthesis according to Fischer-Tropsch there is an urgent need of catalysts for this purpose which possess an activity comparable with that of catalysts obtained by melting as well as a selectivity comparable with that of catalysts prepared by precipitation. Further it is desirable for preparation of these catalysts to be effected in a way that does not have the drawbacks .
of the above-mentioned precipitation or melting route.
An extensive investigation has been carried out by Applicant into the use for hydrocarbon synthesis according to Fischer-Tropsch of catalysts comprising 10~75 parts by weight of one or more metals of the iron group per 100 parts by weight of carrier, together with one or more promoters in a quantity of 1-50% of the metals of the iron group present on the catalyst and which catalysts have been prepared by impregnation of a porous carrier with one or more aqueous solutions of salts of the metals in question of the iron group and of the promoters in question followed by drying and calcining of the composition. It has been found that the selectivity of these catalysts, which can be prepared with good reproducibility in a simple way, is highly dependent on the quotient of the specific average pore diameter (p~ and the specific average particle :, :

diameter (d) of the catalysts. For further information concerning p and d as well as the way :in which these are determined, see Dutch patent application No. 7214397, in which these catalyst data were discussed in detail.
- The investigation concerning the above-mentioned catalysts prepared by impregnation has revealed that these catalysts ~ ~;
with a p of at most 10,000 nm and a d of at most 5 mm, display both an excellent activity and an excellent selectivity when used for hydrocarbon synthesis according ;~
to Fischer-Tropsch, if the quotient p/d is larger than 2.0 (p in nm and d in mm).
The present patent application therefore relates to a process for the preparation of hydrocarbons by catalytic reaction of carbon monoxide with hydrogen, ~15 using a catalyst prepared by impregnation having the above-mentioned properties. ~ ~;
; Comparison of the selectivity of the present catalysts ; prepared by impregnation with that of the afore-mentioned ~-catalysts prepared by melting~ reveals that the latter generally display such a low selectivity that for a hydrocarbon synthesis in which the selectivity is of major importance - as in the present patent application - "
these catalysts are of no interest and need not be further discussed. Comparison of the activity of the present oatalysts prepared by impregnation with that o~ the ~:

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'',' ~`' ' afore-mentioned catalysts prepared by precipitation, reveals that the former show a considerably larger increase in activity per degree of rise of the reaction temperature and moreover that the maximum temperature at which these catalysts can still be employed bearing in mind the selectivity is considerably higher. The possibility of employing the present catalysts prepared by impregnation at a higher temperature than those prepared by precipitation, offers, in addition to the gain in activity, the advantage that the waste heat of the process can be utilised more effectively, for example for the production of steam with a higher pressure and higher temperature than is possible with the catalysts prepared by precipitatlon.
In the process according to the invention the starting material has to be a mixture of hydrogen and carbon ~;
monoxide. Such a mixture can very suitably be prepared ~ ~`
; by the partial combustion of a material containing carbon and hydrogen. Examples of such materials are lignite, anthracite, coke, crude petroleum and fractions thereof, as well as oils produced from tar sand and from bituminous shale. During the partial combustion the feed, in a finely dispersed form, is con~erted with the aid of oxygen or ~
air enriched with oxygen, if desired, into a gas mixture ~ ;
comprising inter alia, hydrogen, carbon monoxide, carbon dioxide, nitrogen and water. In the partial combustion steam ;

;' is preferably employed as temperature moderator. The partial combustion is preferably carried out at a temperature between 900 and 1500C and a pressure ~etween 10 and 50 bar. In order to be able to remove impurities such as ash, carbon- ~-aceous material and hydrogen sulphide from the gas obtained ? in the partial combustion, which gas has a temperature of more than 1000C, this gas must first be cooled down to a temperature between 100 and 200C. This cooling may be very suitably effected in a boiler in which steam is generated by means of the waste heat. ~he cooled gas may be freed from practically all solid matter by washing with water.
After this wash, in which the temperature of the gas has fallen to 20-80C, the gas is further purified by removal of hydrogen sulphide and carbon dioxide. This may be very suitably effected by means of the ADIP process or the SULFINOL
process.
In the process according to the invention the starting material is a mixture of hydrogen and carbon monoxide having ;~
preferably a molar ratio between 0.5 and 3. If the process ;
` 20 is carried out using an iron catalyst, special preference is given to the use of a mixture of hydrogen and carbon monoxide with a molar ratio between 0.5 and 1.5, and in the case of a cobalt or nickel catalyst to the use of a mixture of hydrogen and carbon monoxide with a molar ratio -~
between 1.2 and 2~5. If the available mixture of hydrogen ~ ;

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and carbon monoxide does not have the requlred molar ratlo, this .may be adjusted by adding hydrogen or carhon monoxide.
An increase of the hydrogen content of the mixture with respect to the carbon monoxide content may also be very suitably effected by submitting the mixture to the well-known water gas shift reaction.
The process according to the invention is preferably carried out at a temperature of 200-350~C, a pressure of 10-70 bar and a space velocity of 500-5000 and in particular of 500-2500 Nl gas/litre of catalyst/hour. If the process is carried out using an iron catalyst special preference is given to a reaction temperature of 250-325C and a reaction pressure of 20-50 bar and, when a cobalt or nickel catalyst is employed, to a reaction temperature of 220-300C and a reaction pressure of 10-35 bar.
Catalysts employed in the process according to the invention `
comprise 10-75 parts by weight of one or more metals of the iron group, per 100 parts by weight of carrier, together ;' with one or more promoters in a quantity of 1-50% of the ;~
quantity of metals of the iron group present on the catalyst.
With respect to metals of the iron group, preference is given to the use of catalysts comprising 15-50 and in particular 20-40 parts by weight of one or more of these metals per ' 100 parts by weight of carrier. With respect to the promoters, ` 25 preference is given to the use of catalysts comprising one .~

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`--- 10 or more pro~oters in a quantity of ~ 40 and in particular 10-20% o~ the metals of the iron group ~resent on the catalyst.
As promoters for the catalysts according to the inventlon a large number of elements is eligible. As examples the following may be mentioned: alkali metals, alkaline-earth metals, metals of Group VIB, Ti, Zra Al, Si, As, V, Mn, Cu, Ag, Zn, Cd, Bi, Pb, Sn, Ce, Th and U. Very suitable combinations - of promoters for iron catalysts according to the invention consist of an alkali metal such as K, a readily reducible metal such as Cu or Ag and~ if desired, a metal that can only be reduced with difficulty such as Al or Zn. An example of a very suitable iron catalyst according to the invention is a catalyst comprising iron, potassium and copper on silica as the carrier. I~ in the process according to the invention use is made of an iron catalyst comprising K as selectivity promoter, preference is given to the use of a catalyst comprising not more than 0.15 g of K per-g of Fe, because it has been found that, when higher K concentrations are used, the selectivity does not increase any fther, ~hereas,-owing to coke deposition on the catalyst the stability decreases sharply. Very suitable promoter combinations for cobalt catalysts according to the invention consist of an alkaline-earth metal and Th, U or Ce. An example of a very suitable cobalt catalyst according . ~ . .. .
to the invention is a catalyst comprising cobalt, magnesium ;~ ~;

and thorium on silica as the carrier. Other very suitable ' ! ', ~'~,,. .`
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cobalt catalysts according to the invention are catalysts comprising Co/Cr, Co/Zr, Co/Zn or cO/n~g on silica as the carrier Very suitable promoters for nickel catalysts according ~`~ to the invention are Al, Mn, Th, ~,~ and U.
In the process according to the invention catalysts are employed which have been prepared by impregnation of a porous carrier with one or more aqueous solutions of salts of metals of the iron group and salts of promoters followed by drying and calcining of the composition. The carrier used to prepare the catalysts according to the invention may be amorphous or crystalline. Examples of suitable carriers are silica, alumina, zirconia, thoria, magnesia, boron oxide as well as combinations thereof such as silica-alumina and ~`~
silica-magnesia~ Other suitable carriers are zeolites such as mordenite, faujasite and zeolite-omegaO Zinc oxide has also proved to be a suitable carrier for the present catalysts. ~ ;
In the preparation of the catalysts the salts can be incorporated into the carrier in one or more steps. The material is dried between the individual impregnation steps. Application of a multi-step impregnation technique may be necessary for the preparation of catalysts with a high metal content.
The salts of the metals of the iron group an~ the salts of the promoters may be incorporated into the carrier separately `~
or together starting from one solution. An attractive manner of incorporating the metals of the iron group and the promoters . ,; .

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'~': '," ' '; into the carrier is the dry i~pregnation technique, according to ~ihich the carrier is contacted with an aqueous solution of the salts concerned, which aqueous solution has a volume substantially equal to the pore volume of the carrier. Absorption of the aqueous solution may be facilitated by heating the mixture gently. If this method of preparation is chosen for the preparation of catalysts with a high metal load, it may be necessary to carry out more than one dry impregnation and dry the material between the individual impregnation steps. ~;
The catalyst employed in the process according to the ; invention should have a specific average pore diamter (p) of at most 10,000 nm and a specific average particle diameter (d) of at most 5 mm. As regards p preference is given to catalysts with a p of at most 1000 nm and in particular with ~;
, a p of at most 500 nm. The choice of d is determined by the ; way in which the process is carried out. A very suitable embodiment of the process according to the invention is that ;;;~
in which the feed is passed upwards or do~nwards through a vertically disposed reactor ccntaining a fixed or movingbed of the catalyst parkicles concerned. The hydrocarbon synthesis ~`
may, for example, be effected by passirg the feed upwards through a v`ertically disposed catalyst bed, the gas being " `
made to flow at such a rate as to cause expansion of the '!,`' ,`` ,, catalyst bed. If desired, the hydrocar~on synthesis may also ~}~ `

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be effected using a suspension of the catalyst in hydro-carbon oil. According as the hydrocarbon synthesis is effected using a fixed catalyst bed, an expanded catalyst bed or a ~ catalyst suspension, preference is given to the use of catalyst ', 5 particles with a d between 1 and 5 mm, 0.5 and 2.5 mm and 20 and 150 ~, respectively. ~hen the hydrocarbon synthesis is carried out using a fixed catal~st bed, waxy hydrocarhons will be deposited on the catalyst, as a result of which the ~ activity decreases. To get round this difficulty the catalyst ! ~0 may be was~ed periodically, for example for some hours per 1000 run hours, with a solvent for the above-mentioned heavy hydrocarbons. A suitable solvent for this purpose is for ~ ;
example a mixture of methyl ethyl ketone and toluene. ~he above-mentioned deactivation of the catalyst is preferably counteracted by continuously washing the catalyst with a fraction of the product prepared in the hydrocarbon synthesis.
For this purpose preference is given to a fraction with an initial boiling point above 200C and a final boiling point ;
below 550C. An additional advantage of the above-mentioned -continuous wash of the catalyst is that temperature control ; during the highly exothermic hydrocarbon synthesis reaction is simplified. ;-The reaction product which in the process according to the invention leaves the reactor contains in addition ~ 25 to hydrocarbons and oxygen-containirlg hydrocarbons whose ;" molecular weight extends over a wide range, inter alia water, ~;

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nitrogen, carbon dio~ide and unconverted carbon monoxide and hydrogen. If the process according to the lnvention is carrled out in what is known as "once-through" operation, the C3~ fraction is separated from the reaction product as end product. If the process according to the invention is carried out in what is known as "recycle" operation, the C3+ fraction is likewise separated from the reaction product as end product, but now the rest of the reaction product after reduction of the carbon dioxide content, if necessary, is recycled to the reactor, applying a bleed stream to avoid the build~up of nitrogen, inter alia.
The invention is now elucidated by means of the following example. i~
FXAMPLE
23 catalysts (catalysts A-D and i-19) were tested for the hy~rocarbon synthesis according to Fischer-Tropsch. The preparation of the catalysts was carried out as follows.
~`l Catalyst A -~ -A boiling solution of 2886 g of Fe~N03)3.9 aq and 76 g `~
of Cu(N03)2.3 aq in 10 l of water was added with stirring ~; ;
to a boiling solution of 1000 g of anhydrous Na2CO3 in 10.5 l of water. To the mixture thus obtained were added in succession ~ `~
130 g of anhydrous Na2C03 and 14 . 4 g of clay. After filtration ~ of the mixture the filter cake was washed with hot water `s~25 until the filtrate was free of sodium and then washed with l~.` ~ ' ;~ " ' ' ,~,.'` ' . : -` ', '`.'~ ' . :- :

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10 l of an aqueous solution which contained 10 g of NHI~MO3 per litre. The filter cake was Icneaded with 240 g of soda water glass, dried for 24 hours at 110C and ground. The catalyst A thus prepared by precipitation comprised 3.6 parts by weight of Cu, 4.1 parts by weight of Na and 23 parts by weight of SiO2 per 100 parts by weight of Fe.
Catalyst B
In a similar way as described hereinbefore for catalyst A, a catalyst B was prepared by precipitation which comprised

4.43 parts by weight of Cu, 3.95 parts by weight of Na and 20.5 parts by weight of SiO2 per 100 parts by weight of Fe.
Catalyst C '~ , An aqueous solution of 225 g of Fe(N0~)3.9 aq, an aqueous ' solution of 5.9 g of Cu(NO3)2.3 aq and an aqueous solution of 3.2 g of KNO3, were combined and the volume of the combined solution was made up with water to 150 ml. The solution was ;~
incorporated into 125 g of SiO2 with a total pore volume ~:
of 150 ml. After some time the co~nposition was dried at 120C, ;~, calcined for 1 hour at 500C, ground and sieved. The catalyst C thus prepared by impregnation comprised 25 parts by weight of Fe, 1.25 parts by weight of Cu and 1 part by weight of K per 100 parts by weight of SiO2.
''Catàlys't's' ~' a'_d' 1'-'19 `~
,25 In a similar way as described hereinbe'fore for catalyst ; '~

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. ~ ''`' ,, 9'~ 3 C, catalysts D and 1-19 were prepared by impregnation.
In the preparation of the catalysts containing Th, ~g, Co, Al, Cr and/or Zn as promoters, use was made of aqueous solutions Or nitrates of the elements concerned. In the preparation of the catalyst which contained Zr as promoter use was made of an aqueous solution of zirconyl chloride.
The compositions of the catalysts as well as their specific average pore diameters and specific average particle diameters are given in Table A. The values given in the table for p and d were determined by means of nitrogen adsorption/desorption, mercury penetration and sieve analysis as described in Dutch patent application No. 7214397. ;
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, Cata~y,ts A-l) and 1-19 w~re testeci for h~/drocarbon synthesis accordin~; to Fischer-Tropsch in a 250-ml reactor containing a fixed catalyst bed of the catalyst in question, with a volume varying between 25 and 75 ml. Before being ~ 5 used for the hydrocarbon synthesis all the catalysts were - first reduced for 2 hours with a mixture of hydro~en and , nitrogen (molar ratio 3:1), at atmospheric pressure, 280C
and a superficial gas velocity of l.6 m/sec.
For the preparation of hydrocarbons a mixture of carbon ,; lO monoxide and hydrogen was passed over the catalysts at elevated temperature and pressure. The reaction product was worked ~ up by cooling it down at the reaction pressure in two steps :' first to 150C which caused separation of a heavy liauid `~
phase and then to 15C which caused separation of a light 15 liquid phase and a gas phase. The composition of the reaction '-~ product was determined by means of TBP-GLC analysis.
'~~ The reaction conditions used in the experiments as well as the results obtained are given in Table B.
With the exception of the experiments mentioned under 19 and l9A all other experiments were carried out in once-through operation. The activities and selectivities listed relate to the situation at run hour 500, with the exception of those mentioned under 18, 18A, 18B, 19 and l9A.
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experiment the catalyst was continuously washed at a space velocity of 0.6 l.l. 1.hour 1 with part of the heavy liauid phase which had separated from it when cooling the reaction product to 150C. The results mentioned under 19 and 19A ~
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(v/v) mixture of methyl ethyl ketone and toluene. The results ;;;
mentioned under 18, 18A and 18B relate to the situation at run hours 400, 800 and 900, respectively. I~lashing of , the catalyst took place-between run hours 800 and 900~ ; ;`

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Of ~he 42 experi~ents given in Table ~ only experiments 9-42 are experiments according to the invention. In these experiments catalysts were used which had been prepared by lmpregnation and which satisfied the conditions: p < 10,000 nm, d < 5 mm and p/d > 2. Experiments 1-8 are outside the scope of the invention and have been included in the patent application for comparison. Experiments 1-4 were carried out using catalysts prepared by precipitation. Experiments 5-8 were carried out using catalysts which, although prepared by impregnation, did not satisfy the condition p/d > 2.
The experimental results presented in Table B give rise to the following remarks~
1. Comparison of exp. 1 with exp. 2 and comparison of `~
exp. 3 with exp. 4 reveals that with the catalysts prepared by precipitation, an increa~e in activity ~, due to the use of a higher temperature, is accompanied ~ by a sharp decrease in selectivity. The activity and '` selectivity observed in exp. 1 are substantially in line with what may be expected of a good catalyst.
The activity and selectivity found are comparable with ~I those attained by Sasol in commercial application of the process of Lurgi Chemie.
2. Comparison o~ exp. 5 with exp. ~, 113 16 and 18 and comparison o~ exp. 7 with exp. 33 reveals that the catalysts prepared by impregnation satisfying the condition p/d ~ 2 have a higher activity and selectivity than ~
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catalysts prepared by impregnation which do not satisfy this condition.
3. It is generally assumed that khe maximum temperature and pressure at which Co-catalysts prepared by precipitation may be used are about 215C and 15 bar, respectively.
The use of higher temperatures and/or pressures leads ~-~
to very rapid deactivation of the catalyst. The experimental work has proved that the Co-catalysts according to the invention may be used at considerably higher temperatures and pressures.
4. Comparison of exp. 12, 13 and 14 with each other reveals that the activity of the catalysts according to the invention at first increases with increasing pressure until a maxi~um value has been reached. Upon a further increase in pressure a decrease in activity occurs.

5. Comparison o~ exp. 21 with 22 and comparison of exp. -23 with 24 reveals that with the catalysts according - ~ ~
to the invention, an increase in activity due to the ;
~` use of a higher temperature, is accompanied by only a slight decrease in selectivity.

6. Comparison of exp. 24 with 25 reveals that with the catalysts according to the invention, the use o~ a lower H2/C0 ratio leads to an increase in selectivity `
and a decrease in activity.

7, Comparison of exp. 17 with 40 reveals that with the `~
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~.
. . . ~ . . .

~01~ 5 of Cu by Co leads to an increase in both activity and selectivity.

8. Comparison of exp. 11, 21 and 23 with each other reveals that with the Fe-catalysts according to the invention, an increase in K-content leads to an increase in selectivity.
A very high K-content, however, has a detrimental effect on the activity. The experimental work has further shown that an increase in the K-content of the Fe-catalysts according to the invention leads to a sharp increase of oxygen-containing compounds in the reaction product. ;
Thus, when using an Fe-catalyst according to the invention comprising 5 parts by weight of K per 25 parts by weight of Fe, about 80 per cent by weight of oxygen-containing compounds was found in the reaction product.

9. Comparison of exp. 35, 36, 37, 38, 39 and 41 with each ~; :
other reveals that in addition to the promoter combination Th/Mg frequently used in the Co-catalysts prepared by precipitation, each of these elements individually, as well as the elements Cr, Zn and Zr, are likewise very suitable for use as promoters for the Co-catalysts according to the invention. The promoters may be ranked as follows in order of increasing attractiveness for this application: Zn, Th/Mg, Mg, Th, Cr and Zr.

10, Comparison of exp. 11 with 15 reveals that with the P 25 catalysts according to the invention a reduction in ~` ~

.~

~V~ 95 particle size leads to an increase in activity.

11, Co~.parison of exp. 18 and 18A with 19 and l9A revea~s that the activity of the catalysts according to the invention is better maintained when a heavy fraction of the reaction product is continuously passed over the catalyst.

12. Comparison of exp. 18 with 18B reveals that a discontinuous wash of the deactivated catalys with a solvent leads to a complete recovery of the activity and selectivity.
Comparison of exp. 18 with 18A gives an impression of the deactivatlon that tends to occur. Comparison of exp. 18A with 18B gives an impression of the effect of washing.

13" Comparison of exp. 21 with 29, 20 with 31 and 41 with 42 reveals that for the c~alysts according to the invention not only SiO2 but also ZnO, MgO-A12O3 and Al2O3 are -very suitable carriers.

~`~`; ;'' ''`

~ , . . ; ~ ~ , -

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the preparation of hydrocarbons by catalytic reaction of carbon monoxide with hydrogen, characterized in that a catalyst is used comprising 10-75 parts by weight of one or more metals of the iron group per 100 parts by weight of carrier, together with one or more promoters in a quantity of 1-50% of the quantity of metals of the iron group present on the catalyst, which catalyst is prepared by impregnation of a porous carrier with one or more aqueous solutions of salts of the metals in question of the iron group and the promoters in question followed by drying and calcining of the composition, which catalyst has such a specific average pore diameter (p) of at most 10,000 nm and such a specific average particle diameter (d) of at most 5 mm that the quotient p/d is larger than 2 (p in nm and d in mm).

2. A process as claimed in claim l, characterized in that the molar ratio between hydrogen and carbon monoxide in the feed lies between 0.5 and 3.

3. A process as claimed in claim 1, characterized in that this process is carried out at a temperature of 200-350°C, a pressure of 10-70 bar, and a space velocity of 500-5000 Nl gas/litre of catalyst/hour.

4. A process as claimed in claim 1, characterized in that this process is carried out at a temperature of 200-350°C, a pressure of 10-70 bar, and a space velocity of 500-2500 Nl gas/litre of catalyst/hour.

5. A process as claimed in any one of claims 1-3, characterized in that a catalyst is used comprising 15-50 parts by weight of one or more metals of the iron group per 100 parts by weight of carrier.

6. A process as claimed in any one of claims 1-3, characterized in that a catalyst is used comprising 20-40 parts by weight of one or more metals of the iron group per 100 parts by weight of carrier.

7. A process as claimed in any one of claims 1-3, characterized in that a catalyst is used comprising one or more promoters in a quantity of 5-40.

8. A process as claimed in any one of claims 1-3, characterized in that the catalyst used has been prepared by a dry impregnation technique in which the carrier is contacted with an aqueous solution of the salts, the aqueous solution having a volume substantially equal to the pore volume of the carrier.

9. A process as claimed in any one of claims 1-3, characterized in that a catalyst is used with a p of at most 1000 nm.

10. A process as claimed in any one of claims 1-3, characterized in that this process is carried out using a fixed catalyst bed, an expanded catalyst bed or a catalyst suspension and using catalyst particles with a d between 1 and 5 mm, 0.5 and 2.5 mm and 20 and 150 µ, respectively.

11. A process as claimed in any one of claims 1-3, characterized in that this process is carried out using a fixed catalyst bed and in that the catalyst is washed periodically or continuously with a solvent for heavy hydrocarbons.

12. A process as d aimed in any one of claims 1-3, characterized in that this process is carried out using a fixed catalyst bed and the catalyst is washed continuouly with a fraction of the product prepared in the hydrocarbon synthesis.

13. A process as claimed in any one of claims 1-3, characterized in that the molar ratio between hydrogen and carbon monoxide in the feed lies between 0.5 and 1.5 and in that an iron catalyst is used.

14. A process as claimed in any one of claims 1-3, characterized in that this process is carried out at a temperature of 250-325°C and a pressure of 20-50 bar and in that an iron catalyst is used.

15. A process as claimed in any one of claims 1-3, characterized in that an iron catalyst is used comprising an alkali metal and a readily reducible metal as promoters.

16. A process as claimed in any one of claims 1-3, characterized in that an iron catalyst is used comprising an alkali metal, a readily reducible metal and a metal that can only be reduced with difficulty as promoters.

17. A process as claimed in any one of claims 1-3, characterized in that a catalyst is used comprising iron, potassium and copper on silica as the carrier.

18. A process as claimed in any one of claims 1-3, characterized in that an iron catalyst is used comprising potassium in a concentration of at most 0.15 g of potassium per gram of iron.

19. A process as claimed in any one of claims 1-3 characterized in that a catalyst is used comprising iron, potassium in a concentration of at most 0.15 g of potassium per gram of iron, and copper on silica as the carrier.

20. A process as claimed in any one of claims 1-3, characterized in that the molar ratio between hydrogen and carbon monoxide in the feed lies between 1.2 and 2.5 and in that a cobalt or nickel catalyst is used.

21. A process as claimed in any one of claims 1-3, characterized in that this process is carried out at a temperature of 220-300°C and a pressure of 10-35 bar and in that a cobalt or nickel catalyst is used.

22. A process as claimed in any one of claims 1-3, characterized in that the molar ratio between hydrogen and carbon monoxide in the feed lies between 1.2 and 2.5, that a cobalt or nickel catalyst is used, and that the process is carried out at a temperature of 220-300°C and a pressure of 10-35 bar.

23. A process as claimed in any one of claims 1-3, characterized in that a cobalt catalyst is used comprising an alkaline-earth metal and Th, U
or Ce as promoters.

24. A process as claimed in any one of claims 1-3, characterized in that a cobalt catalyst is used comprising an alkaline-earth metal and Th, U
or Ce as promoters, that the molar ratio between hydrogen and carbon monoxide in the feed lies between 1.2 and 2.5 and that the process is carried out at a temperature of 220-300°C and a pressure of 10-35 bar.

25. A process as claimed in any one of claims 1-3, characterized in that a catalyst is used comprising cobalt, magnesium and thorium on silica as the carrier that the molar ratio between hydrogen and carbon monoxide in the feed lies between 1.2 and 2.5 and that the process is carried out at a temperature of 220-300°C and a pressure of 10-35 bar.

26. A process as claimed in any one of claims 1-3, characterized in that a cobalt catalyst is used comprising one of the following elements: Zn, Mg, Th, Zr and Cr as the promoter.

27. A process as claimed in any one of claims 1-3, characterized in that a cobalt catalyst is used comprising one of the following elements: Zn, Mg, Th, Zr and Cr as the promoter, that the molar ratio between hydrogen and carbon monoxide in the feed lies between 1.2 and 2.5 and that the process is carried out at a temperature of 220-300°C and a pressure of 10-35 bar.

28. A process as claimed in any one of claims 1-3, characterized in that a nickel catalyst is used comprising Al, Mn, Th, W or U as the promoter.

29. A process as claimed in any one of claims 1-3, characterized in that a nickel catalyst is used comprising Al, Mn, Th, W or U as the promoter that the molar ratio between hydrogen and carbon monoxide in the feed lies between 1.2 and 2.5 and that the process is carried out at a temperature of 220-300°C and a pressure of 10-35 bar.