NO144631B - PROCEDURE FOR THE PREPARATION OF HYDROCARBONES BY CONVERSION OF SYNTHESIC GAS OVER A CRYSTLINIC ALUMINUM SILICATE-CONTAINING CATALYST - Google Patents

Description

This invention relates to an improved method

to convert synthesis gas, i.e. mixtures of gaseous carbon oxides with hydrogen or hydrogen donors, into hydrocarbon mixtures.

Methods for converting coal and other hydrocarbons such as natural gas into a gaseous mixture consisting essentially of hydrogen and carbon monoxide and/or dioxide are well known. Those that are of greatest importance are based either on partial combustion of the fuel with an oxygen-containing gas or on high-temperature reaction between the fuel and steam,

or on a combination of these two reactions. An excellent summary of the state of the art regarding gas production, including synthesis gas, from solid and liquid fuels,

is given in Encyclophedia of Chemical Technology, published by Kirk-Othmer, second edition, volume 10, pages 353-433, (1966),

Interscience Publishers, New York.

It is also well known that synthesis gas is converted to reduction products of carbon monoxide, such as hydrocarbons, at from about 149 to about 454°C, under from about one to one thousand atmospheres of pressure and over a fairly wide catalyst-

area. For example, the Fischer-Tropsch process produces,

which has been investigated to a large extent, a number of liquid hydrocarbons, some of which have been used as low-octane petrol. Catalysts which have been investigated in this and related methods include those based on iron, cobalt, nickel, ruthenium, thorium, rhodium and osmium or their oxides.

But it has not yet proved possible to identify

any combination of catalyst and processing conditions that will produce liquid hydrocarbons in the boiling range of gasoline, containing highly branched paraffins and significant amounts of aromatic hydrocarbons, both of which are required for high quality gasoline, or to selectively produce aromatic hydrocarbons that are particularly rich in compounds in the range of benzene to xylenes. An overview of the state of this technique is given in "Carbon Monoxide-Hydrogen Reactions", Encyclopedia of Chemical Technology, published by Kirk-Othmer, Second Edition, Volume 4, pp. 446-488, Interscience Publishers, New York, N.Y.

It has recently been discovered that synthesis gas can be converted into oxidized organic compounds and these compounds can then be converted into higher hydrocarbons, especially high-octane petrol, by catalytic contact between synthesis gas and a carbon monoxide reduction catalyst, after which the thus produced conversion product is brought into contact with a special zeolite catalyst type in a separate reaction zone. This two-step conversion is described in DT-OS No. 2,438,252.

It has now been discovered that valuable hydrocarbon mixtures can be prepared directly by reacting synthesis gas, i.e. mixtures of hydrogen and carbon monoxide, possibly together with other carbon oxides, or equivalents of such mixtures,

in the presence of certain heterogeneous catalysts comprising intimate mixtures of two or more components.

According to the invention, a method for the production of hydrocarbons is provided. The method is characterized by bringing synthesis gas, with a volume ratio between hydrogen and carbon oxides within the range 0.2 to 6.0, at a temperature within the range 26.0 to 455°C and a pressure of 3-200 atm. in contact with a catalyst comprising a metal or a metal compound having catalytic activity for the reduction of carbon monoxide,

and a crystalline aluminosilicate having a network formed by SiO^ and AlO^ tetrahedra cross-linked by sharing oxygen atoms, and having a pore diameter greater than 5 Angstroms, a silica to alumina ratio of at least 12

and a steering index in the range from 1 to 12, at a space velocity of 500 to 50,000 volumes of gas (STP) per volume catalyst.

The preferred crystalline aluminosilicates are ZSM-5, ZSM-11, ZSM-12, ZSM-35 and ZSM-38. The preferred metals are those from group 8, but metals from groups IB (e.g. copper),

IIB (eg zinc) and/or UIB (eg thorium) and their compounds can give excellent results. Mixtures of all these together with promoters, such as chromium oxide, are of value.

The ratio of the reducing component for carbon monoxide to crystalline aluminum silicate can be adjusted to regulate the character of the product, i.e. determine whether components in the gasoline-boiling range, paraffins/aromatics or internal olefins should predominate. By "internal olefins" here is meant olefins where the double bond does not include a terminal carbon atom.

The volume ratio between hydrogen and carbon oxides is advantageously maintained within the range from 0.2 to 6.0.

Depending on the choice of components and the particular reaction conditions used, significant quantities of liquid mixtures can be obtained which are rich in one or more olefins, branched paraffins and aromatic hydrocarbons and which are highly suitable for forming high-octane petrol or petro-chemicals. One can thus choose catalyst and operating conditions to produce ordinary gaseous hydrocarbons that have at least one carbon-to-carbon bond as the dominant product, or hydrocarbon streams that are rich in internal olefins. Such products are valuable as petrochemical feedstock, and for the production of petroleum fuel that can be liquefied. The catalysts used not only produce highly desirable products with good selectivity, but in many cases produce them either in extraordinarily high yield or under mild conditions or sometimes both. With thorium oxide as a reducing component for carbon monoxide, synthesis gas is converted at surprisingly low temperatures and pressures. With a catalyst for methanol synthesis of the zinc-copper-chromite type as the reducing component, the conversion rate of synthesis gas is increased and instead of methanol, large amounts of hydrocarbons having at least one carbon-to-carbon bond are obtained. With a Fischer-Tropsch type catalyst, increased amounts of aromatic hydrocarbons are obtained. Furthermore, when the preferred crystalline aluminosilicate component is used, the catalytic activity is maintained for unusually long periods of time, and when aromatic hydrocarbons are produced, these are very rich in

toluene and xylenes.

A typical purified synthesis gas will have the following volume composition on an anhydrous basis: hydrogen 51, carbon monoxide 40, carbon dioxide 4, methane 1 and nitrogen 4.

The synthesis gas can be produced from fossil fuels by any of the known methods, including such in situ gasification processes as the underground partial combustion of coal and petroleum deposits. The term fossil fuels, when used here, is meant to include anthracite coal and bituminous coal, lignite, crude petroleum, shale oil, oil from tar sands, natural gas and also fuels derived from simple physical separations or more profound conversions of these materials, including coking coal, petroleum coke, gas oil, residues from petroleum distillation and two or more of any of the foregoing materials in combination. Other carbon-containing fuels, such as peat, wood and cellulose-containing waste materials, can also be used.

The raw synthesis gas produced from fossil fuels will contain various contaminants, such as particles, sulfur and metal carbonyl compounds, and will be characterized by a ratio between hydrogen and carbon oxides that will depend on the fossil fuel and the particular gasification technology used. Because of the effect of the subsequent conversion steps, it is usually desirable to purify the raw synthesis gas by removing impurities. Technical methods for such cleaning are known and are not part of this invention. But it will not be necessary to remove substantially all sulfur contaminants when thorium oxide is used as a reducing component for carbon monoxide, since thorium oxide is not irreversibly poisoned by sulfur compounds. If necessary, it is further preferred to adjust the volume ratio between hydrogen and carbon monoxide to the range of from 0.2 to 6.0 before the application of this invention. If the purified synthesis gas is excessively rich in carbon oxides, it can be brought within the preferred range by the well-known water gas exchange reaction. If, on the other hand, the synthesis gas is excessively rich in hydrogen, it can be adjusted to the preferred range by adding carbon dioxide or carbon monoxide. Purified synthesis gas adjusted to have a volume ratio of hydrogen to carbon oxides of from 0.2 to 6.0 will be referred to as "adjusted" synthesis gas.

Synthesis gas equivalents that are approved in the industry can also be used. Mixtures of carbon monoxide and steam or of carbon dioxide and hydrogen are considered, for example, in order to provide adjusted synthesis gas for in situ reactions. Furthermore, when the method according to the invention is used to produce hydrocarbon mixtures rich in aromatic hydrocarbons, which will be more fully described, a hydrogen donor, such as methane, methanol or higher alcohols, can advantageously be added together with the feedstock .

The component which is characterized by catalytic activity for the reduction of carbon monoxide can be selected from any of the industrially approved catalysts for the production of hydrocarbons, oxidized products or mixtures thereof from synthesis gas, and constitutes from 0.1 to 99 percent by weight, preferably from 1 to 80 percent by weight, of the active components of the catalyst. Broadly speaking, these catalysts include those approved as methanol synthesis catalysts. Fischer-Tropsch synthesis catalysts and variations thereof. Commercial methanol synthesis catalysts comprising metals or oxides of zinc together with chromium oxide, or of zinc and copper together with chromium oxide or aluminum oxide or known modifications thereof, are included. In reality, synthesis gas will be converted to form reduction products of carbon monoxide, such as alcohols and hydrocarbons, at from about 149 to about 454°C under a pressure of from about 1 to 1000 atmospheres over catalysts from a fairly wide range. The predominant type of catalyst which causes conversion includes the metals or oxides selected from the group consisting of IB, IIB, UIB, IVB, VIB and VIII alone or in combination with each other. In particular, they include the metals or oxides of zinc, iron, cobalt, nickel, ruthenium, thorium, rhodium and osmium. Catalysts of the Fischer-Tropsch type based on iron, cobalt or nickel, and especially iron, are particularly suitable for the production of oxidized hydrocarbon products having at least one carbon-to-carbon bond in their structure. With the exception of ruthenium, virtually all industrially approved synthesis catalysts contain chemical and structural promoters. These promoters include copper, chromium oxide, alumina, alkaline earths, rare earth alkalis and alkalis. Alkalis, e.g. carbonates of compounds from group IA in the periodic table, and especially of potassium, are of particular importance with iron catalysts, since these greatly increase the product distribution. Carriers, such as diatomaceous earth, sometimes seem lucky.

It should be noted that the carbon monoxide reducing component may be provided as elemental metal or as corresponding metal compounds. When producing and using such catalytic substances, one or more partial or complete conversions from elemental metal to compounds will often take place, or vice versa. As an example, pure iron, roasted in an oxygen atmosphere in the presence of added aluminum and potassium nitrates, provides a composition containing 97% Fe^ O^, 2.4% Al2°3 0<3 0.6% K ^ O together with trace amounts of sulfur and carbon. This composition catalyzes, after reduction with hydrogen at about 454°C, the conversion of synthesis gas at a temperature in the range from about 182 to 221°C and at an elevated pressure up to about 20 atmospheres. 65% of the carbon monoxide is reduced to a mixture consisting of about one-third weight percent of hydrocarbons that boil in the range 9 3 to about 360°C, and about two-thirds of oxidized compounds, mostly alcohols, in the same boiling range. Manganese lumps can be used as a catalyst.

The crystalline aluminosilicate component of the heterogeneous catalyst is characterized by a pore size greater than about 5 Angstroms, i.e. it is capable of sorbing paraffins having a single methyl branching and also normal paraffins, and it has a ratio of silica and alumina of at least 12. For example, zeolite A with a silica to alumina ratio of 2.0 is not useful in this invention, and it has no pore dimensions greater than about 5 Angstroms.

The crystalline aluminum silicates referred to here, also known as zeolites, are characterized by a rigid crystalline skeleton structure composed of SiO^ and AlO^ tetrahedra cross-linked by sharing oxygen atoms. Such a structure causes precisely defined pores. Exchangeable cations are present to balance the negative charge on the A104 tetrahedron.

The preferred zeolites useful in this invention are selected from a recently identified class of zeolites

with unusual properties that are of themselves able to

catalyze the conversion of aliphatic hydrocarbons to aromatic hydrocarbons in commercially desirable yields. They are also usually very effective in alkylation, isomerization, disproportionation and other reactions involving the participation of aromatic hydrocarbons. In many cases they have unusually low alumina content, i.e. high ratios of silicon dioxide to alumina, and they are very active even at ratios of silicon dioxide to alumina that exceed 30.

Furthermore, they maintain their crystallinity for long periods despite the presence of steam even at such high temperatures as to induce irreversible breakdown of the crystal skeleton of other zeolites, e.g. those of type X and A. When carbonaceous deposits form, these can be removed from them by firing at temperatures higher than usual to restore activity, although in many environments they exhibit very low coking ability leading to very long flow times between regenerating burns.

The ratio between silicon dioxide and aluminum oxide

which is discussed obviously only concerns the tetrahedrally coordinated silicon and aluminium. Although zeolites with a ratio between silicon dioxide and aluminum oxide of at least 12 are useful, it is preferred to use zeolites that have a ratio of at least 30. After activation, such zeolites achieve an intracrystalline sorption capacity for normal hexane that is greater than that for water, and can be called "hydrophobic". Such zeolites are advantageously used in the present invention.

The zeolites useful as catalysts in the present invention readily sorb normal hexane and have

a pore dimension greater than about 5 Angstroms. Moreover, their structure must provide controlled access limited to certain larger molecules. It is sometimes possible from a known crystal structure

to assess whether such controlled access exists. If, for example, the only pore window in a crystal is formed by 8-membered rings of oxygen atoms, then the introduction of molecules with a larger cross-section than normal hexane will be significantly prevented and the zeolite is not of the desired type. Zeolites with windows of 10-membered rings are preferred, although excessive wrinkling or pore blocking can render these zeolites substantially ineffective.

Zeolites with windows of twelve-membered rings generally do not appear to provide sufficient control to produce the beneficial transformations desired by the present invention, although structures can be obtained, due to pore blocking or other reasons, which can be used.

Rather than attempting to judge from crystal structures whether or not a zeolite has the required directed access, a simple determination of the "directed index" can be performed by continuously passing a mixture of equal weight amounts of normal hexane and 3-methyl-pentane over a small sample, approximately 1 gram or less, of zeolite at atmospheric pressure in accordance with the following procedure. A sample of the zeolite, in the form of pellets or extrudate, is crushed to a particle size that is roughly that of coarse sand, and is placed in a glass tube. Before testing, the zeolite is treated with an air flow of 538°C for at least 15 minutes. The zeolite is then purged with helium and the temperature is adjusted between 288 and 510°C to give a total conversion of between 10

and 60%. The mixture of hydrocarbons is carried at a space velocity of 1 liquid volume per hour (i.e. 1 volume of liquid hydrocarbon per volume of catalyst per hour) over the zeolite with a dilution with helium which gives a molar ratio between helium and total amount of hydrocarbons of 4:1. After 20 minutes on steam, a sample of the effluent is taken and analyzed, most conveniently by gas chromatography, to determine the fraction that remains unchanged of each of the two hydrocarbons.

The "Management index" is calculated as follows:

The steering index is approximated as the ratio of the pressure distillation rate constants for the two hydrocarbons. Catalysts which are suitable for the present invention are those which use a zeolite which has a steering index of from 1.0 to 12.0. Control index (CI) values for some typical zeolites including some not within the scope of this invention are:

One must of course remember that the real nature of

this index, and the technique with which it is determined, makes it possible for a given zeolite to be tested under somewhat different conditions and thus obtain different control indices. The steering index seems to vary somewhat with the severity of the operation (transformation). It may therefore be possible to select test conditions to obtain several control indices for a particular zeolite, which may be both within and outside the above range from 1 to 12. The scope of this invention includes any zeolite that exhibits a control index in the range of 1 to 12 in some combination of conditions which is within the scope of the determination method stated above, whether or not it gives an index outside this range in other such combinations of conditions.

Particularly good examples of this class of zeolites are given with the zeolites ZSM-5, ZSM-11, ZSM-12, ZSM-35 and ZSM-38. ZSM-5 is described in U.S. Pat. U.S. Patent No. 3,702,886, ZSM-11 U.S. Patent No. 3,709,979, ZSM-12 U.S. Patent No. 3,832,449 and ZSM-35 and -38. applications No. 582,061 and No. 528,060, respectively, both filed November 29, 1974.

When the specifically described zeolites are prepared in the presence of organic cations, they are substantially catalytically inactive, possibly because the intracrystalline free space is occupied by organic cations from the form-forming solution. They can be activated by heating in an inert atmosphere at 538°C for 1 hour, for example, followed by base yielding with ammonium salts followed by calcination at 538°C in air for from 15 minutes to 24 hours. The presence of organic cations in the mold-forming solution may not be absolutely essential for the formation of this particular type of zeolite, but appears to be beneficial. Natural zeolites can sometimes be converted to this type of zeolites by various activation processes or other treatments, such as base yield, steaming, alumina extraction and calcination, alone or in combinations. Natural minerals that can be treated in this way include ferrierite, brewsterite, stilbite, dachiardite, epistilbite, heulandite and chinoptilolite.

The zeolites can be used in hydrogen form, metal-exchanged form or ammonium form. The metal cations which may be present include any of the cations of the metals from groups I to VIII of the periodic table, although metal cations from group IA should not be present in large amounts.

The most preferred zeolites are those which have a crystal skeleton density in the dry hydrogen form of not significantly less than about 1.6 grams per cubic centimeter. The dry density for known structures can be calculated from the number of silicon atoms plus aluminum atoms per 1000 cubic angstroms, as stated e.g. on page 19 of the article on zeolite structures by W. M. Meier in "Proceedings of the Conference on Molecular Sieves, London, April 1967", published by the Society of Chemical Industry, London, 1968. When the crystal structure is unknown, the crystal skeleton density can be determined by classic pycnometer techniques. It can, for example, be determined by immersing the dry hydrogen form of the zeolite in an organic solvent which is not sorbed by the crystal. It is possible that the unusually sustained activity and stability of this class of zeolites is associated with their high crystal anionic skeleton density of not less than about 1.6 grams per cubic centimeter. cubic centimeter. This high density must of course be associated with a relatively small amount of free space inside the crystal, which can be expected to result in more stable structures. But this free space seems to be important as the site of catalytic activity.

In the following are given crystal skeleton densities for some typical zeolites including some that are not within the scope of this invention:

The heterogeneous catalysts according to this invention can be prepared in different ways. The two components can be produced separately in the form of catalyst particles, for example as pellets and extrudates, and simply mixed in the appropriate proportions. The particle size of a single component particle can be quite small, for example from about 20 to about 150 microns, when it is intended to be used in fluidized bed operation, or it can be as large as up to about 12.7 mm for operation at fixed bed.

The two components can be mixed as powders and formed into a pellet or extrudate, where each pellet contains both components substantially in the appropriate proportions. Binders such as clay can be added to the mixture. Alternatively, the component having catalytic activity for the reduction of carbon monoxide can be combined with the crystalline aluminosilicate component by means such as impregnation of the zeolite with a salt solution of the desired metal, followed by drying and calcination. Base exchange of the crystalline aluminosilicate component may also be used in some selected cases to effect the introduction of some or all of the carbon monoxide reducing component. Other means of forming the intimate mixture include precipitation of the carbon monoxide reducing component in the presence of the crystalline aluminum silicate, electroless deposition of metal on the zeolite and deposition of metal from the vapor phase. Various combinations of the above preparation methods will be apparent to those skilled in the catalyst manufacturing industry, and also the necessity to avoid techniques which tend to reduce the crystallinity of the crystalline aluminum silicate. - From the foregoing, it will be clear that the mixtures used in the method according to this invention can have varying degrees of intimacy. At one extreme, when using 12.7 mm pellets of the carbon monoxide reducing component mixed with 12.7 mm pellets of the crystalline aluminosilicate, substantially all locations within at least one of the components will be within a distance of no more than 6.35 mm from some of the other component, regardless of the ratio between the two components that are used. With pellets of different sizes, e.g. 12.7 and 6.35 mm, again substantially all places within at least one of the components will be within a distance of no more than about 6.35 mm from the other component. These examples illustrate the lower end of the degree of intimacy required for the practice of this invention. At the other extreme, crystalline aluminosilicate particles of about 0.1 micron particle size can be ball milled together with colloidal iron oxide of similar particle size followed by pelletization. In this case, substantially all locations within at least one of the components will be within a distance of no more than about 0.05 microns from any of the other component. This is an example of about the highest degree of intimacy that is practical.

In the method according to this invention, synthesis gas is brought into contact with the heterogeneous catalyst at a temperature of from about 204 to 538°C, preferably from 260 to 454°C, at a pressure of from 1 to 1000 atmospheres, preferably from 3 to 200 atmospheres, and at a volume-hour space velocity of from 500 to 50,000 volumes of gas (STP)

per volume of catalyst, or at equivalent contact time if a fluidized bed is used. The product stream containing hydrocarbons, unreacted gases and steam can be cooled and hydro-

the carbons are extracted according to any technique known in the industry. The recovered hydrocarbons may be further separated by distillation or other means to recover one or more products, such as high octane gasoline, propane fuel, benzene, toluene, xylenes, or other aromatic hydrocarbons.

Some embodiments of the invention are indicated for illustration

in the following examples.

Example 1

Thorium oxide was prepared according to the method of Pichler and Ziesecke, as described in "The Isosynthesis",

U.S. Bureau of Mines Bulletin, 488 (1950), which essentially involves sweeping of Th (NO^)^ solutions with Na 2 CO 2 ~ solutions followed by filtration, washing and drying at 100°C.

A composite catalyst was prepared by ball milling equal amounts by weight of NH 2 ZSM-5 and dried thorium oxide gel, pelletizing and calcining at 538°C for 10 hours. Three tests were carried out, each at 427°C, at 85.05 kg/cm 2 overpressure and with a mixture of hydrogen and carbon monoxide with an I 2 /CO ratio of 1.0. The first and second trials comprised thorium oxide and HZSM-5, each used separately, while the third trial used a heterogeneous catalyst containing both thorium oxide and HZSM-5.

The results are summarized in table 1.

Example 2

ZnO on a support of A₂O₂ was obtained from a commercial source and was used as the carbon monoxide reducing component. It contained 24 wt% ZnO. HZSM-5 was used as the acidic crystalline aluminosilicate component.

The heterogeneously composed catalyst was prepared by ball-milling four parts of HZSM-5 for one part of the ZnO/A^O^ catalyst, followed by pelletization. Two experiments were carried out, both at 316°C, 52.50 kg/cm^ overpressure and with a mixture of hydrogen and carbon monoxide with a ^/CO ratio of 4. The first experiment used the ZnO/A^O^ catalyst alone, while the second experiment used a composite catalyst containing both ZnO/Al2O3 and HZSM-5 catalyst.

The results are shown in table 2.

Aromatic compounds in Cr+

(% by weight) none 71.8

Example 3

A methanol synthesis catalyst was prepared containing the following weight percentages: copper - 54.55, zinc - 27.27, chromium - 9.09 and lanthanum - 9.09 on an oxygen free basis. A composite catalyst was then prepared from equal parts of this component and HZSM-5 using 5% graphite as binder. Two experiments were carried out, each at 316°C, 52.50 kg/cm<2> overpressure and using a feed of a mixture of hydrogen and carbon monoxide with an I^/CO ratio of 2, and the experiments are summarized in table 3.

As shown, the contact time (reciprocal of space velocity) with respect to the methanol catalyst component is very similar in the two experiments, and is slightly lower with the composite catalyst.

The composite catalyst shows a much larger

production of hydrocarbons, particularly hydrocarbons with a higher carbon number than methane, than the carbon monoxide-reducing component alone.

Example 4

The carbon monoxide reducing component was a commercial iron oxide type ammonia synthesis catalyst containing small amounts of K, Ca and Al promoters. The zeolite component contained 65% HZSM-5 and 35% alumina binder. The heterogeneously composed catalyst contained 75% of the iron component and 25% of the zeolite component, and was formed by ball milling the components and then pelletizing the resulting powder.

Three trials were conducted at 371°C, 18.55 kg/cm 2 overpressure

and with a mixture of hydrogen and carbon monoxide with an H^/CO ratio of 1.0.

The results are summarized in table 4.

Experiment H elucidates the selectivity of the iron component in the absence of HZSM-5, the C 5 + hydrocarbons containing only 1.9% aromatic compounds. In experiment (J), a reaction zone containing HZSM-5 was placed after the reaction zone containing the iron catalyst. It can be seen that the aromatic selectivity was not significantly changed. But in experiment (K), the intimate mixture of HZSM-5 and the iron component gave about a seven-fold increase in aromatic selectivity.

Example 5

The catalyst in this example was prepared by impregnating NH4ZSM-5 containing 35% alumina binder with a solution of Fe(NO^)^ > drying the catalyst and calcining at 538 C for 10 hours. The finished catalyst contained 3% iron. Synthesis gas (^/CO = 1) was reacted over this catalyst at 371°C, 36.05 kg/cm<2> overpressure and 30 seconds contact time, and the following conversions and products were obtained.

Example 6

The catalyst in this example was an intimate mixture of 57.4% ilmenite sand (FeO-TiO 2 ), 21.3% HZSM-5 and 21.3% alumina binder. Synthesis gas (H^/CO = 1) was reacted over said catalyst at 371°C, 18.55 kg/cm overpressure and 10 seconds contact time, and the following conversions and products were obtained.

Example 7

The catalyst in this example was an intimate mixture of 41.2% magnetite (Fe 2 ), 29.4% HZSM-5 and 29.4% alumina binder. Synthesis gas (H2/CO = 1) was reacted over said catalyst at 371°C, 18.55 kg/cm<2> overpressure and 10 seconds contact time, and the following conversions and products were obtained.

Example 8

The catalyst in this example was an intimate mixture of 41.2% iron carbide, 29.4% HZSM-5 and 29.4% alumina binder. Synthesis gas (H-/C0 = 1) was reacted over said catalyst at

and 2

371 C, 18.55 kg/cm overpressure and 10 second contact time, and the following conversions and products were obtained.

Example 9

The catalyst in this example was prepared by impregnating an extrudate comprising ZSM-5 crystalline zeolite containing about 35% alumina as binder with a solution of iron [FeCNO^^] followed by drying and reduction with hydrogen at temperatures of about 510°C. Three different amounts of iron impregnation were prepared as indicated in Table 10. Synthesis gas (H 9 /CO = 2) was brought into contact with the catalyst at a temperature of 316 o C and a pressure of 14.00 kg/cm 2 gauge. The results obtained were the following:

Example 10

The catalysts used in this example comprised a mixture of ZSM-5 alumina extrudate (ratio 65/35) and a copper methanol synthesis catalyst. In experiments 912-1 and -2 the ZSM-5/Cu synthesis catalyst volume ratio was 2.9/2, and in experiments 913-3 to -5 the ZSM-5/Cu synthesis catalyst volume ratio was 4/1 . The ZSM-5 alumina extrudate was also mixed with an iron-ammonia synthesis catalyst at a ratio of 4/1 and used as a catalyst in experiments 903-1, -2 and -6. The operating conditions used and the results obtained in the respective experiments are indicated in table 10 below.

Example 11

A thorium oxide ZSM-5 catalyst (no alumina) prepared as indicated in Example 1 above was used in two separate experiments for comparison with a similar catalyst containing alumina binder as shown below. In these examples, synthesis gas (H 2 /CO = 1) was brought into contact with the catalyst at a temperature of 427°C and a pressure of 84.00 kg/cm 2 gauge. The results obtained are shown in table 11 below.

Example 12

Ruthenium dioxide has been used as a Fischer-Tropsch catalyst to convert synthesis gas to paraffin wax under high pressure and low temperature (120-220°C). But at a higher temperature (300°C) only methane is formed. Ruthenium-on-aluminium has also been used for synthetic conversion to form gaseous, liquid and solid hydrocarbons, but again methane becomes the main product at temperatures higher than 250°C. No aromatic compounds are formed when using these catalysts. It has now been found that ruthenium in combination with HZSM-5 produces gasoline containing aromatic compounds, with high yield from synthesis gas over a wide temperature range.

Example A

A 5% ruthenium on ZSM-5 catalyst was prepared by vacuum impregnation of 10g NH4~ZSM-5 with an 18 ml aqueous solution containing 1.25 g RuCl^-S^O. After drying in vacuum, the catalyst was air-calcined in an oven at 538°C for two hours. This resulted in a conversion of the ammonium form of ZSM-5 to the hydrogen form.

Example B

A 1% Ru/ZSM-5 catalyst was prepared using the procedure of Example A, except that 20 g of NH 2 -ZSM-5 was used with a 36 ml aqueous solution containing 0.5 g of RuCl 3 * 3 H 2 O. ;Example C ;The conversion of synthesis gas (H 2 /C 0 ) was carried out in a continuous flow reactor with a fixed bed. The stainless steel reactor was charged with 5.5 g of the 5% Ru/ZSM-5 catalyst prepared in Example A. The catalyst was pre-reduced with flowing hydrogen at 399°C and a pressure of 52.50 kg/cm<2> positive pressure for three hours. ;The conversion of synthesis gas (H,/C0) was carried out at 52.50 kg/cm overpressure. 304 C, WHSV = 0.32 and H 2 /CO = 2/1. The results and the detailed hydrocarbon distribution are set out in Table 13 below. High conversion was obtained with good selectivity for liquid (C5+) products. The liquid product contained<* >25% aromatic compounds and had octane numbers R+0 = 77 and R+3 =92.

Example D

Synthesis gas conversion was carried out under substantially the same conditions as in Example C, except that 5.5 g of 1% Ru/ZSM-5 prepared in Example B was used. The results are listed in Table 13 below. A high conversion to hydro-. carbons rich in C2+ bg containing 13.8% aromatic compounds.

Claims (1)

Process for the production of hydrocarbons, characterized by bringing synthesis gas, with a volume ratio between hydrogen and carbon oxides within the range 0.2 to 6.0, at a temperature within the range 260 to 455°C and a pressure of 3-200 atm. in contact with a catalyst comprising a metal or a metal compound having catalytic activity for. reduction of carbon monoxide, and a crystalline aluminum silicate which has a network formed by SiO^ and AlO^ tetrahedra cross-linked by sharing oxygen atoms, and sbm has a pore diameter greater than 5 Angstroms, a ratio of silicon dioxide and alumina of at least 12 ocj a steering index finn the .range from 1 to 12", at a rbm rate of 500 to 50,000 volumes of gas (STP) per volume •catalyst.