JP2008544060A - Method for converting synthesis gas to hydrocarbons in the presence of silicon carbide foam - Google Patents

Abstract

An object of the present invention is to obtain an ideal carrier for an exothermic FT synthesis reaction as compared with a conventional carrier.
To this end, in the presence of hydrogen and in the presence of a metal (optionally added promoter) containing catalyst in a multi-tube reactor containing a catalyst retained on a support based on a rigid cell foam of silicon carbide, monoxide is obtained. A method of converting carbon to C2 ₊ hydrocarbons.
[Selection] Figure 1

Description

The present invention is a method for converting synthesis gas into C ₂₊ hydrocarbons in a silicon carbide foam, in particular a rigid foam of β-SiC, by the Fischer-Tropsch process.

  Fischer-Tropsch process (FT) synthesis using metal catalysts supported on various catalyst supports is known from many documents.

The pamphlets of WO0112323 (A) and WO0154812 (A) (Battelle) refer to carbides as supports and interfacial layers for catalyst systems for FT synthesis.
However, it does not mention the types of carbides that are particularly suitable for use, the details of the crystal phase, and the recommended shape types.

The specifications of US Pat. No. 5,648,312, US Pat. No. 5,677,257, and US Pat. No. 5,711,0093 (Intevep) include specific catalyst supports suitable for FT synthesis (which can be carried out in fixed bed, ebullated bed, or slurry). Are listed.
The catalyst species in these documents are Group IVB and Group VIII metals, or in particular a mixture of zirconium and cobalt.

International Publication No. 011323 (A) International Publication No. 0154812 (A) US Pat. No. 5,648,312 US Pat. No. 5,677,257 US Patent No. 5710093

The catalyst carrier used in the above patent specification is obtained as follows.
That is, a suspension of silica and silicon carbide in a basic solution is formed, droplets are formed, they are separated into spheres, and then the spheres are transferred to an acidic solution to substantially form silica and silicon carbide. Yield a catalyst support containing a homogeneous mixture.
A method for synthesizing hydrocarbons from synthesis gas uses this spherical catalyst carrier.

Attempts have also been made to significantly improve reactor production and manufacturability.
In particular, attempts have been made to increase the amount of CO + H ₂ gas mixture that is converted to hydrocarbons in the reactor.

Accordingly, the present invention eliminates the above disadvantages by converting carbon monoxide to C _{2+ in} the presence of hydrogen and in the presence of a metal-containing catalyst in a reactor containing a catalyst held on a silicon carbide foam-based support. A method for converting to hydrocarbon,
-GHSV is 100-5000h < ^-1 >,
-WHSV is a process for converting carbon monoxide to C2 ₊ hydrocarbons, characterized in that it is carried out at operating conditions of 1-100 h- ¹ .
It is also a method for converting carbon monoxide to C ₂₊ hydrocarbons in the presence of hydrogen and in the presence of a metal-containing catalyst in a multi-tube reactor containing a catalyst held on a support based on silicon carbide foam.

Accordingly, the present invention provides a method for converting carbon monoxide to C2 + hydrocarbons in the presence of hydrogen and in the presence of a metal-containing catalyst in the reactor, the reactor comprising a silicon carbide foam-based support. Containing the supported catalyst, the process is carried out under the following operating conditions:
-GHSV is 100-5000h < ^-1 >,
-WHSV is from ^{1 to} 100 h- ¹ .

GHSV and WHSV are defined as follows (and are calculated as such in the examples): (Gas consists of both CO and H ₂ for GHSV and WHSV at standard temperature and pressure conditions) ):
GHSV = total gas flow rate (cc / min) × 60 / reactor volume occupied by catalyst (particles or bubbles) (cc). This is the reciprocal of the contact time.

WHSV = mass flow rate of gas (CO + H ₂ ) (g / min) / main catalyst metal mass (g).

The present invention also provides a method for converting carbon monoxide to C ₂₊ hydrocarbons in the presence of hydrogen and in the presence of a catalyst comprising a metal of a multi-tube reactor, the multi-tube reactor comprising a silicon carbide The catalyst is supported on a foam-based support.

The novel FT synthesis method uses a novel catalyst support consisting of (or preferably consisting of) SiC, in particular β-SiC foam (monolith).
Preferably the foam is a rigid foam. The catalyst support usually has an arbitrarily controllable structure and consists of a network of interconnected cavities of micron or millimeter size, usually mesopores and macropores.
Preferably, the size of the cavity is 0.3 to 5 mm. Macroscopic structures, in particular cell (network) structures, are created directly during material synthesis, but this eliminates the need for additional shaping normally required with α-SiC based carriers.
However, a carrier based on α-SiC is still useful (not preferred), although it requires post-synthesis molding that is necessary for a macroscopic structure.
Compared to prior art carriers, an ideal carrier for an exothermic FT synthesis reaction is obtained.
This carrier has a number of advantages, especially in terms of operating parameters.
This support is actually a chemically inert support, unlike alumina, which is often inappropriate for the formation of inappropriate metal aluminates that are thought to cause catalyst deactivation. Becomes).
The carrier is a carrier made of a good heat-conducting substance and is perfectly suitable for transferring reaction heat generated in the catalyst mass.
Furthermore, molding as a rigid foam with a connected structure results in better heat transfer properties than when simply molded into granular grains and stacked in a reactor.
The thickness of the solid bridge constituting the rigid foam is smaller than the thickness of the grain or extrudate.
This is advantageous for the diffusion of reactants into the active site and the removal of liquid and gaseous products from the active site, and for improved site-by-site activity.
In the case of a support in the form of granular grains or extrudates, the diffusion of the reaction product through the thicker pore network is lower, causing site clogging problems and reducing the efficiency of the catalyst.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  Various forms of α-SiC, including foam (foam), are widely known in the art, and such foams are available, for example, from Ultramet (Pacoima, California, USA).

β-SiC is prepared by a gas / solid reaction between in situ generated vapor form of SiO and intimately mixed solid carbon (without liquid).
For more detailed literature on β-SiC, reference is made to the following patent applications and patents. These are hereby incorporated by reference.
That is, European Patent Application Publication No. 0313480 (A), European Patent Application Publication No. 0440569 (A), US Pat. No. 5,217,930, European Patent Application Publication No. 0511919 (A), European Patent Application Publication No. 05433751 (A). And European Patent Application Publication No. 0543552 (A).
Since α-form is generally in the form of powder and requires a binder for final macro-molding, β-SiC synthesized by the above method is not limited to the structure of the material. Various macroscopic foams are obtained immediately after synthesis without the addition of (which greatly improves conductivity but can be detrimental to the catalytic process).
Although α-SiC foam is useful, it is not preferred.
In the case of β variety, the crystal is usually face-centered cubic.
Generally, the specific surface area of β-SiC is 5 to 50 m ² / g, more preferably 5 to 40 m ² / g, and preferably 10 to 25 m ² / g.
The pores (pores of the materials that make up the foam) are free of substantial presence of micropores (volume ratio 5), which affects the selectivity of useful products in the processes involved in which reactant and product diffusion problems occur. %), Substantially consisting only of mesopores and macropores.

β-SiC is prepared in the form of foam (cellular).
Reference may be made, for example, to EP 0 537 552, US Pat. No. 5,449,654, US Pat. No. 6,251,819.

  The foam has indefinite pore openings of 300 to 5000 μm, preferably 1000 to 3000 μm. The open porosity (macroporosity) of the SiC foam varies between 30 and 95%, preferably between 30 and 90%, in particular between 50 and 85%.

More precisely, the foam has two porosity levels.
1) Porosity called “cellular porosity” having a millimeter aperture diameter of 0.3-5 mm (preferably 1-3 mm), this foam cell porosity being 30-95%, Preferably it varies between 30 and 90%, in particular between 50 and 85%.
2) The porosity of SiC constituting the foam having a pore size corresponding to the specific surface area.
Attention should also be paid to the presence of other pore networks in the rigid bridges of the support.

This opening structure helps to increase the space velocity without a pressure drop across the catalyst bed.
A low pressure drop helps to reduce compression or reuse in the process.
Also, the diffusion time of the reactants in the SiC foam, particularly β-SiC, is very short, especially less than 1 second.
Therefore, this foam makes it possible to obtain very high productivity, in particular high space velocities.

More precisely, the cellular structure is very fast gas space velocity (ratio of the total flow rate of gas entering the reactor to the empty cross section of the reactor) without excessive pressure drop across the catalyst bed. Useful to use.
The low pressure drop has the advantage of reducing the cost of compressing or reusing the fluid in this method.
The hard β-SiC foam with its surface impregnated with active catalytic metal (egg shell impregnation) is comparable to a millimeter grain stack deeply impregnated with the same proportion of catalytic metal.
The surface bed of catalytic metal deposited on the foam is shown to be used more efficiently than the same amount of metal deeply impregnated with β-SiC grains.
In fact, the Fischer-Tropsch reaction is limited in productivity by internal particle diffusion of reactive gas species (CO and H ₂ ).
Also, the thin active site thickness for the catalyst surface region increases the removal rate of liquid and gaseous reaction products, and the conversion frequency of the reactant per active site is advantageous.

Also, the foam can be used in a crush foam, thus greatly reducing the apparent volume of the catalyst (the weight per unit volume is greatly increased).
This reduction ratio is, for example, 2 to 10, in particular 4 to 6.

This β-SiC has very good mechanical properties and is suitable for use as a catalyst support in a fixed bed or “fixed slurry” process.
Due to its very good thermal conductivity, ie much higher thermal conductivity than metal oxides, hot spots on the catalyst surface are limited.
The selectivity of useful products will be further enhanced.
The foam structure synthesized by the method described above is interconnected throughout the metal structure.
This is advantageous for heat conduction throughout the metal because there is no heat insulating region in the case of a molded structure in the presence of a non-heat-transferring inorganic binder.

Due to the connectivity of the rigid foam structure and the high heat transfer properties of the SiC material (α or β), the appearance of hot spots due to reactant exotherm is less than the multiparticulate catalyst attached to the oxide or similar support.
Regardless of the reactor used, better heat conduction results in high spatial temperature uniformity on the one hand, locally (from the catalytic site to the SiC support) and on the other hand (over the entire rigid foam). can get.
The amount of heat released per unit volume of the foam (reactor) also decreases as the cell porosity of the foam increases.
Therefore, the release and removal of heat in contact with the walls (such as heat exchangers and reactors) can be controlled by this cell porosity.

Due to this characteristic, the rigid foam of the present invention is
1) Low thermal conductivity at the particle contact,
2) Random stacks of fixed beds of catalyst particles (dense or not) well known in the prior art, which are more prone to hot spots because the fixed internal particle porosity is about 0.35-0.40, Very good properties.
In addition to these thermal benefits, an overall mechanical strength is added that is better than normal catalyst particles that are subject to wear due to mutual friction, either when loaded into the reactor or during operation of the process.

  This thermo-mechanical property of β-SiC makes it suitable for use as a catalyst phase support in a variety of high thermal methods.

Further, the absence of the binder contributes to maintaining the thermal conductivity of the carrier at all points of the carrier.
The absence of the binder avoids reaction with the catalyst species (otherwise the activity is lost over time).

According to one aspect of the invention, the catalyst support contains more than 50% by weight β-type silicon carbide.
According to a preferred embodiment, the catalyst support contains from 50% to substantially 100% by weight, preferably substantially 100% β-type silicon carbide foam.

According to one aspect of the present invention, the rigid foam consists solely of silicon carbide, which is mostly β-type and the remainder is α-type, and there are production wastes such as carbon, silicon and their compounds. Is added.
The catalytic nature of the material is provided by surface treatment and / or chemical physical active phase deposition.

The catalyst of the present invention comprises the above catalyst carrier to which one or more metals are added and optionally a promoter that is catalytically active.
As the main catalyst metal (main active catalyst metal), a Group VIII metal such as cobalt, iron, and ruthenium is used as in the prior art. Cobalt is particularly preferable.
Iron is also particularly preferred. As before, a promoter can be used at the same time.
The promoter may be another Group VIII metal, Zr, K, Na, Mn, Sr, Cu, Cr, W, Re, Pt, Ir, Rh, Pd, Ru, Ta, V, Mo, and mixtures thereof. Formed of a metal selected from the group consisting of:
Of these, Mo and Zr are preferred.

The content of the main metal (especially cobalt, especially of the group consisting of cobalt, iron, ruthenium) (or catalyst species, ie active catalyst species) is usually 1-50 with respect to the final weight (total amount) of the catalyst. %, Preferably 3 to 20%, in particular up to 10%.
The content of promoter, in particular molybdenum or zirconium, is conventionally 0.1 to 15% by weight, in particular 2 to 10% by weight, based on the final weight of the catalyst.
The primary metal / promoter weight ratio is 10: 1 to 3: 1 as is conventional, which is the preferred range.

A catalytic metal is deposited as in the prior art.
For example, the pore volume (β-SiC foam metal pore volume) is impregnated with a metal salt, such as cobalt nitrate.
The egg shell method can also be used, which is by adding a drop of ambient temperature metal salt solution to a hot support (previously heated support foam), for example, a solution of cobalt nitrate in air on the surface of the support at 250 ° C. Adhere (metal precursor adhesion).
Another impregnation method involves completely immersing the SiC foam-based support in a solution containing one or more precursor salts in the desired active phase, and then removing the soaked foam and drying it in air (air flow). is there.
This operation is repeated several times until the solution containing the active phase salt is completely depleted.
This operation is repeated several times until the desired carrier impregnation rate is obtained.
The impregnated support is then dried.

The support impregnated in the various ways described above is then treated as follows: dried in air at 100 ° C. for 2 hours and then calcined in air at 350 ° C. for 2 hours to form one or more precursors. Convert the salt to the corresponding oxide.
The calcined product is reduced with a hydrogen stream at 400 ° C. (or 300 to 550 ° C.) for 2 hours to obtain a metal foam composed of active phase components (or at least part of the active phase components).
The reduction can be carried out in other ways, i.e., not hydrogen stream, CO with a reducing flow (CO and H ₂₎ which is itself a reaction flow: emphasized that can be variously changed and H ₂ ratio (adjusted) Must.
The reduction temperature can be changed within a wide range of 400 ° C., and the reduction pressure may be equal to or higher than the environmental pressure.

The Fischer-Tropsch synthesis reaction is usually carried out under the following operating conditions.
Total pressure: 10 to 100, preferably 20 to 50 atmospheres.
Reaction temperature: 160-260 ° C., particularly 160-250 ° C., preferably 180-250 ° C., more specifically 180-230 ° C.
_H 2 / CO ratio of the initial synthesis gas: 1.2 to 2.8, preferably 1.7 to 2.3.
Certain operating conditions are given to help obtain very good results.
GHSV: 100 to 5000 h ⁻¹ , preferably 150 to 3000 h ⁻¹ .
WHSV: ^{1 to} 100 h ⁻¹ , preferably 1 (advantageously 5) to 50 h ⁻¹ .

The process according to the invention serves to increase productivity (ie space time yield, STY), which is very high for all hydrocarbon species or only for C ₄₊ cuts.
Productivity (ie space time yield, STY) is expressed in moles of CO converted to product per hour per mole of catalyst species.
Alternatively, STY = CO mole feed flow rate (mol / min) × conversion / number of moles of catalyst species (mol) × 60.
The unit is simply represented by h- ¹ .

According to one aspect, the method of the invention is carried out under the following operating conditions:
Productivity of hydrocarbons in excess of 3 h ⁻¹ , preferably ¹ to 100 h ⁻¹ , in particular 5 to 100 h ⁻¹ (ie the number of converted CO moles per hour per mole of catalyst species),
Productivity of C4 ₊ hydrocarbons in excess of 3h- ¹ , in particular 1-50h- ¹ , preferably 5-50h- ¹ (ie the number of converted CO moles per hour per mole of catalyst species).
In general, the STY value of hydrocarbons exceeds 3 moles (i.e. converted CO moles per hour per mole of catalyst species), in particular 1 (preferably 5) to 100 moles (i.e. 1 per mole of catalyst species). The STY value of C ₄₊ cut is in particular 1 (preferably 5) to 50 moles (ie the number of moles of converted CO per hour per mole of catalyst species).
In particular, the contact time of the present invention (= 3600 / GHSV) is less than 2 and even less than 1 second (VSHV is greater than 1800 h ⁻¹ and even greater than 3600 h ⁻¹ ).
GHSV, WHSV, STY (productivity) are defined as follows (and are calculated as such in the examples) (the gas is CO and GHSV and WHSV at standard temperature and pressure conditions and It consists of both H _2):
GHSV = total gas flow rate (cc / min) × 60 / reactor volume occupied by catalyst (particles or bubbles) (cc). This is the reciprocal of the contact time.
WHSV = mass flow rate of gas (CO + H ₂ ) (g / min) / main catalyst metal mass (g).
STY = CO molar feed flow rate (mol / min) × conversion / number of moles of catalyst species (mol) × 60.

The method according to the invention is in particular over 10 for example,
It is preferably carried out in a multi-tube reactor consisting of more than 100, preferably 1000 to 100,000 tubes, in particular 2000 to 10,000 tubes.
Each tube contains a β-SiC foam coaxial cylindrical element, which was previously impregnated with a catalytic metal species.

Such a reactor consists of SiC foam as a catalyst support and is effective for the Fischer-Tropsch synthesis reaction.
This reactor may have a built-in heat exchanger and removes heat from the exothermic reaction.
This is usually designed and constructed as a multi-tube heat exchanger and is suitable for removing heat generated in the tube where the (exothermic) synthesis reaction takes place in the shell.

  The process according to the invention can be carried out upstream or downstream of the reactor, ie upstream or downstream of the reaction gas in the reactor.

In the upstream mode, the flow rate is adjusted to react under conditions close to “slurry”.
In a normal “slurry”, the liquid is obtained by entrainment of particles and by overflow overflow or bottom uptake during recirculation, and the propellant gas contacts the liquid catalytic element.
Thus, in a conventional “slurry” reactor, the liquid produced in the reactor contains a catalyst in the form of particulates of the liquid stream that is maintained in the reactor and is naturally recirculated in the reactor.
The propellant gas is simply introduced and brought into contact with the liquid by a conventional distribution element.

The present invention is suitable for adjustment to a state free from the drawbacks of entrainment of catalyst particles while obtaining the same effect as the “slurry” mode (controlled gas / liquid contact).
This is a particularly important advantage when the cost of the catalyst is high, and the separation (filtration) of the entrained particles from the liquid drawn downstream and the regeneration of the particles must be carried out in a delicate manner. This is a particularly important advantage due to the high cost.
Further, the processing capability can be further increased.

More specifically, this conventional slurry reactor principle has two advantages and two main drawbacks.
As an advantage, the catalyst used is fine powder (dp50, 30 to 200 μm), and the catalyst performance is not limited in principle by internal mass transfer.
Another advantage is that the continuous phase of the reactor is a liquid phase, so that the reaction heat transfer in this reactor is relatively good, especially when implemented in a fixed bed reactor with a continuous downstream gas flow. Is also much better.
The main disadvantage of conventional slurry reactors is that this catalyst, which is a fine powder (which is very expensive), must always prevent (and thus lose) the liquid phase from being removed from the reactor. The prevention is essential because it is clearly a product of Fischer-Tropsch synthesis.
The second drawback is the “backmixing” of the liquid-solid suspension with gas that limits unit volume conversion, and the coalescence of bubbles that limits the gas-liquid transition, and the resulting productivity.

When the method of the present invention using the upstream reaction gas flow in the reactor is carried out, the continuous phase of the reactor is also a liquid phase, so that one of the advantages of conventional slurries, ie, the ability to remove good reaction heat is maintained. Become.
In this case, the main active catalytic metal deposited on the foam is held in a thin layer (100 μm) and the risk of restriction due to internal transfer of material is greatly reduced, as is the case with conventional slurry reactors.
However, the disadvantage of this reactor, which is the risk of catalyst loss due to entrainment in liquid entrainment, no longer exists because the catalyst is fixed to the β-SiC rigid foam filling the reactor tube.
In addition, the cellular structure of this rigid foam is advantageous in that it limits the size of the bubbles and thus has a large gas-liquid internal region, thus favoring gas-liquid movement and increasing productivity. The medium average dimension (less than 1 cm) limits the back-mixing of the liquid by bubbles, which is generally advantageous in terms of productivity.

Furthermore, if a pump is used to facilitate liquid recirculation from the top to the bottom of the reactor, it becomes possible to select the liquid space velocity and force it.
This is not possible with conventional conventional bubble systems because the liquid recirculation rate is highly dependent on the upstream velocity of the reaction gas.
In order to implement this forced liquid recirculation, a gas / liquid separator at the upstream of the pump supply line at the overflow is provided.
This can limit the recirculation of bubbles, thus limiting backmixing and approaching plug flow conditions (this is the conversion of intermediate products such as petroleum liquid, distillate, kerosene, naphtha and From the point of view of selectivity, it is advantageous for all chemical reactions).

Also, in the upstream reactant gas flow embodiment, the mechanical wear of the support / catalyst assembly (which is stationary in this case) is severe due to the support / catalyst particulates (in this case moving). Compared to conventional “slurry” systems that experience wear due to bubble bursts under mechanical stress.
Therefore, the cost incurred by the catalyst is reduced.

  Downstream implementations correspond to those typically performed for fixed bed reactions that produce liquids from gases.

More specifically, the implementation of the method of the present invention in the downstream reaction gas flow reactor corresponds to that normally performed for high exothermic reactions in a fixed bed catalytic reactor.
In fact, in these cases, it is well known to use conventional multi-tube reactors whose design and implementation are very similar to shell and tube heat exchangers.
The chemical reaction therefore takes place in a tube filled with particulate catalyst.
In contrast, the shell itself is filled with a heat transfer fluid or water that is converted to steam.
In this reactor, the possibility of removing the reaction heat generated in the catalyst tubes depends on the gas velocity and the effective thermal conductivity of all the catalyst particles packed in each tube.
However, the present invention differs from the conventional multi-tube reactor concept in that the tube is filled with SiC rigid foam rather than catalyst particles.
Thereby, a continuous solid phase in each reaction tube is formed.
On the other hand, when a granular catalyst bed is used, the thermal contact interface between particles becomes low (disaggregation between solid phase elements).
The result is that the thermal conductivity of the β-SiC rigid foam impregnated with the catalyst is better than that of the catalyst particles.
Therefore, this foam increases the efficiency of heat transfer from the catalyst tube to the heat exchange fluid or steam, and the risk of hot spots in the catalyst mass that are well known to cause loss of selectivity and reactor safety. Helps to eliminate.
Actually, conventionally, heat transfer efficiency is a limiting factor of the reactor tube diameter.
In conclusion, the present invention is useful for carrying out the reaction with a tube having a diameter longer than that of the conventional method, and also for reducing the number of tubes per reactor per equivalent product, in terms of ease of construction and reactor cost. You can get obvious benefits from

Similarly, removal of reaction heat per reactor unit volume can be reduced by increasing the cellular porosity of the foam.
By diluting the catalyst particles with an inert granular solid, the same effect can be obtained with a conventional fixed particle bed.
A critical advantage of the rigid foam according to the invention is that the same results can be achieved without a solid diluent and without a pressure drop across the catalytic reactor.

Like conventional fixed bed systems, internal diffusion of the support / catalyst phase is a limiting factor due to the millimeter size of the particles used.
One convenient treatment is to deposit an active metal around the particles.
One advantage of the present invention is that the same ambient impregnation technique can be utilized for rigid foams.
An advantage over other conventional fixed bed systems of the present invention is that the pressure drop is determined by the cellular porosity of the rigid foam and thereby the reaction gas space velocity can be adjusted independently.

  According to another embodiment of the present invention, a multi-tube design reactor using downstream reaction gas comprises a tube filled with β-SiC foam, partly impregnated with active metal and partly impregnated with granular catalyst. Have.

In fact, the downstream reaction gas reactor tube can be filled with support / catalyst particles (support is SiC, preferably β-SiC, particle size is millimeter) and SiC rigid foam (impregnated with catalyst) at the top of the same tube ) Can be filled in the form of hard blocks as described above.
It is actually known that most of the heat is generated in the early stages of the reaction and thus from the chemical reaction kinetics at the top of the tube.
Thus, the presence of the foam at the top serves to take advantage of the above advantages from a heat transfer perspective.
Also, the presence of particles at the bottom is economical because it reduces the amount of foam (more expensive).

According to one more specific preferred embodiment, the linear foam / particle distribution varies between 1: 3 and 1: 1, with about 1: 2 being advantageous.
This means that the particles account for about 2/3 of the useful part of each tube and the foam accounts for about 1/3.
If the support is in the form of particles, the support may be conventional, for example alumina or silicon carbide (preferably β-type).

The foam used in the reactor is uniform or, in one embodiment, the pore size or cavity size is inclined (especially along the reactor tube).
In particular, the pore size (or cavity size) of the foam may vary along the gas flow (in the direction of the gas flow) as the size decreases.
For example, in three parts having the same length, the foam diameter changes from 2500 to 3000 μm (for example, 2700 μm) to 1200 to 1800 μm (for example, 1500 μm) and finally to 700 to 1200 μm (for example, 1100 μm). have.
Thus, the reaction can be optimized taking into account the products that are sequentially produced along the flow axis of the catalyst bed.

  Figures 9a to 9d are possible flow diagrams of a reactor for practicing the present invention.

FIG. 9a is an example of upstream mode operation.
A syngas suction line 2 extending to the distribution element 3 is provided at the bottom of the reactor 1.
Syngas or synthesis gas is a mixture of hydrogen and carbon monoxide and is supplied for the Fischer-Tropsch reaction.
The reactor 1 is filled with a liquid 4.
The syngas is a bubble in the distribution element 3 in the liquid 4.
The syngas bubbles rise in the liquid 4 along the tube 5.
This tube 5 contains a mass of catalyst on a β-SiC foam support.
Thus, a Fischer-Tropsch reaction occurs in the tube 5.
The heat exchanger 6 is provided between the tubes.
The heat transfer fluid intake pipe 7 and the heat transfer fluid takeout pipe 8 are provided on the input side and the output side of the heat exchanger 6 for circulation of the heat transfer fluid.
The reactor 1 is further provided with a pipe 9 for extracting a gas effluent generated by the Fischer-Tropsch synthesis at the upper part, and for extracting a liquid effluent generated by the Fischer-Tropsch reaction at the bottom. A conduit 10 is provided.

FIG. 9b shows the deformation operation in the upstream mode.
According to this variant, the reactor is provided with a liquid overflow 11.
Liquid is withdrawn via a lead-in line 12 connected to the liquid overflow 11. The pump 13 draws in the liquid in the intake pipe 12 and recirculates the liquid portion by forced circulation, and re-injects the liquid at the bottom of the reactor 1 through the liquid intake pipe 14.
The other liquid portion is taken out via the take-out conduit 15.

FIG. 9c shows an example of downstream mode operation.
In this configuration, the reactor 21 includes a syngas intake pipe line 22 at the top of the reactor.
The syngas descends along the tube 23.
This tube 23 contains a catalyst mass on a β-SiC foam carrier.
A Fischer-Tropsch reaction occurs in tube 23.
The heat exchanger 24 is provided between the tubes.
The heat transfer fluid intake conduit 25 and the heat transfer fluid extract conduit 26 are provided on the input side and the output side of the heat exchanger 24 for circulation of the heat transfer fluid.
The reactor is further provided at its bottom with an extraction line 27 that collects all of the product of the Fischer-Tropsch reaction.

  According to the downstream mode deformation operation shown in FIG. 9d, tube 23 contains catalyst supported on SiC particles at its lower part (up to about 2/3 of its useful length) and at its upper part (useful length). About 1/3) contains a catalyst supported on β-SiC foam.

In the process of the present invention, the hydrocarbon effluent is a mixture of more than 70 mol%, from 50 to 90 mol% C _{6 to} C ₁₂ hydrocarbons, 10 to 50 mol% C _{13 to} C ₂₄ hydrocarbons. Containing a mixture.
The effluent contains a C ₆ -C ₂₅ mixture of more than 80 mol%, preferably more than 90 mol%.

In the method of the present invention, the hydrocarbon effluent is normally contains a C ₁ -C ₂₀ alcohol of less than 10 mol% of branched hydrocarbons and olefins and / or 2 mol%.

In the method of the present invention, the methane / CO ₂ content of the hydrocarbon effluent may be less than 20 mol%.

In the method of the present invention, the hydrocarbon effluent contains a C ₁ -C ₂₀ alcohol of less than 10 mol% of branched hydrocarbons and olefins and / or 2 mol%.

In the method of the present invention, the hydrocarbon effluent exceeds 80 mol%, preferably contain _C 6 _{-C 25} mixture exceeds 90 mol%.

In the process of the present invention, the hydrocarbon effluent has a ratio greater than 6% per C ₇ , C ₈ , C ₉ , C ₁₀ , C ₁₁ , C ₁₂ , and C ₁₃ .

In the process of the present invention, the hydrocarbon effluent has a ratio of greater than 8% for C ₈ , C ₉ , C ₁₀ , and C ₁₁ .

  In the process of the present invention, the hydrocarbon effluent has an olefinic hydrocarbon concentration of less than 1%.

In the process of the present invention, the hydrocarbon effluent contains methane and CO ₂ with a content of less than 20 mol%.

Finally, the method of the invention comprises an improvement step, in particular an improvement step for producing automobile fuel.
This improvement step consists of isomerization and decomposition.

  In this application, unless stated otherwise, ratios are expressed as molar ratios.

Examples The following examples illustrate the invention.

Example 1 (comparison)
In this example, an integral monolithic foam (hard cell foam) β-SiC-based carrier having an average cell diameter (average pore diameter) of about 500 μm and a specific surface area of 11 m ² / g is a pore volume method (pore volume method). ) To impregnate with an aqueous solution containing a cobalt salt of nitrate ester foam.
The mass of the precursor salt is calculated such that the final cobalt content is 30% by weight of the catalyst weight after calcination and reduction.
The impregnated product is then dried at 100 ° C. for 2 hours, and incubated at 350 ° C. for 2 hours in air to convert the precursor salt to the corresponding oxide.
After formation, the product is reduced with a stream of hydrogen at 400 ° C. for 2 hours to obtain an active phase metal foam.
The Fischer-Tropsch synthesis reaction is carried out under the following conditions.
Total pressure: 40 atmospheres
Reaction temperature: 220 ° C.
Catalyst capacity: 20cc
Catalyst mass (support + active phase): 5.0 g
Active phase mass: 1.5 g,
50 cc / min H ₂ + CO (STP),
Dilution 50cc / min Ar (STP),
H ₂ / CO molar ratio: 2,
Reactant / catalyst contact time: 12 seconds (GHSV 300 h ⁻¹ ),
WHSV: 0.95 h- ¹ .
The following hydrocarbon and C ₄₊ hydrocarbon productivity is obtained:
STY _HC = 1.58h ^-1 ,
STY _{C4 +} = 1.14h ^-1 .

Example 2 (Invention)
In this example, an integral monolithic foam (hard cell foam) β-SiC carrier having an average cell diameter (average pore diameter) of about 1500 μm and a specific surface area of 15 m ² / g was impregnated by the method shown in Example 1. Is done.
The mass of the precursor salt is calculated so that the final cobalt content is 10% by weight of the catalyst weight after calcination and reduction.
FIG. 1 shows a carrier, and FIG. 2 shows an enlarged view of the foam thus obtained.
The Fischer-Tropsch synthesis reaction is carried out under the following conditions.
Total pressure: 40 atmospheres
Reaction temperature: 220 ° C.
Catalyst capacity: 18cc
Catalyst mass (carrier + active phase): 4.0 g,
Active phase mass: 0.4 g,
200 cc / min H ₂ + CO,
No Ar dilution,
H ₂ / CO molar ratio: 2,
Reactant / catalyst contact time: 5.5 seconds (GHSV 660h ⁻¹ ),
WHSV: 14.3 h- ¹ .
The following hydrocarbon and C ₄₊ hydrocarbon productivity is obtained:
STY _HC = 7.0 h ⁻¹ ,
STY _{C4 +} = 6.58 h ⁻¹ .

Example 3 (Invention)
The same procedure as in Example 2 is performed under the following conditions.
Total pressure: 40 atmospheres
Reaction temperature: 230 ° C.
Catalyst capacity: 18cc
Catalyst mass (support + active phase): 3.48 g,
Active phase mass: 0.34 g,
200 cc / min H ₂ + CO,
H ₂ / CO molar ratio: 2,
Reactant / catalyst contact time: 5.5 seconds (GHSV 660h ⁻¹ ),
WHSV: 16.4 h- ¹ .
The following hydrocarbon and C ₄₊ hydrocarbon productivity is obtained:
STY _HC = 7.25 h ⁻¹ ,
STY _{C4 +} = 5.41 h ⁻¹ .

Example 4 (Invention)
The same procedure as in Example 2 is performed under the following conditions.
Total pressure: 40 atmospheres
Reaction temperature: 240 ° C.
Catalyst capacity: 18cc
Catalyst mass (support + active phase): 3.48 g,
350 cc / min H ₂ + CO,
H ₂ / CO molar ratio: 2,
Reactant / catalyst contact time: 3.1 seconds (GHSV 1160h ⁻¹ ),
WHSV: 28.7 h- ¹ .
The following hydrocarbon and C ₄₊ hydrocarbon productivity is obtained:
STY _HC = 40h ⁻¹ ,
STY _{C4 +} = 14 h ⁻¹ .

Example 5 (Invention)
The procedure is similar to that of Example 2, but this time the catalyst is supplemented with 2% Zr.
The impregnation procedure is the same as in Example 1, and the zirconium salt is ZrO (NO ₃ ) ₂ .
The same procedure as in Example 2 is performed under the following conditions.
Total pressure: 40 atmospheres
Reaction temperature: 220 ° C.
Catalyst capacity: 36 cc
Catalyst mass: 8.35 g,
200 cc / min H ₂ + CO,
H ₂ / CO molar ratio: 2,
Reactant / catalyst contact time: 10.9 seconds (GHSV 330h ⁻¹ ),
WHSV: 6.8 h- ¹ .
The following hydrocarbon and C ₄₊ hydrocarbon productivity is obtained:
STY _HC = 6.35 h ⁻¹ ,
STY _{C4 +} = 6.0 h ⁻¹ .

Example 6 (Invention)
The procedure is similar to Example 2, but this time the catalyst is crushed and not in the form of a macroscopic foam.
Before pulverization, the foam is impregnated with a solution containing an appropriate amount of cobalt salt (cobalt nitrate) by the aforementioned immersion method.
After drying, heat treatment is performed, the foam containing the cobalt-based active phase is crushed, and then the FT reaction is tested. The volume reduction coefficient is 4-6.
The same procedure as in Example 2 is performed under the following conditions.
Total pressure: 40 atmospheres
Reaction temperature: 220 ° C.
Catalyst capacity: 37cc
Catalyst mass (support + active phase): 22.7 g,
Active phase mass: 2.3 g,
400 cc / min H ₂ + CO,
H ₂ / CO molar ratio: 2,
Reactant / catalyst contact time: 5.5 seconds (GHSV 650h ⁻¹ ),
WHSV: 5.0 h ⁻¹ .
The following hydrocarbon and C ₄₊ hydrocarbon productivity is obtained:
STY _HC = 3.71 h ⁻¹ ,
STY _{C4 +} = 2.69 h ^-1 .

It is an enlarged view of the β-SiC foam used in the present invention, more specifically, a rigid foam. 1 is an enlarged view of a useful catalyst of the present invention. The result which made the flow time by Example 1 a function is shown. The result which made the flow time by Example 2 a function is shown. The result which made the flow time by Example 3 a function is shown. The result which made the flow time by Example 4 a function is shown. The result which made the flow time by Example 5 a function is shown. The result which made the flow time by Example 6 a function is shown. 9a-9d are schematic views of a reactor used in the context of the present invention.

Explanation of symbols

1 reactor
2 Syngas suction line
3 Distribution elements
4 Liquid
5 pipes
6 Heat exchanger
7 Heat transfer fluid intake conduit
8 Heat transfer fluid outlet line 9 Pipe line
10 pipeline
11 Liquid overflow
12 service lines
13 Pump
14 Liquid intake line
15 Extraction pipeline

Claims (23)

A process for converting carbon monoxide to C2 ₊ hydrocarbons in the presence of hydrogen and in the presence of a metal-containing catalyst in a reactor containing a catalyst held on a support based on silicon carbide foam, comprising:
-GHSV is 100-5000h < ^-1 >,
-A process for converting carbon monoxide to C2 ₊ hydrocarbons, characterized in that WHSV is carried out at operating conditions of 1-100 h- ¹ . A process for converting carbon monoxide to C2 ₊ hydrocarbons in the presence of hydrogen and in the presence of a metal-containing catalyst in a multi-tube reactor containing a catalyst held on a support based on silicon carbide foam. A method of converting carbon monoxide according to claim 2 to C ₂₊ hydrocarbons comprising:
-GHSV is 100-5000h < ^-1 >,
-A process for converting carbon monoxide to C2 ₊ hydrocarbons, characterized in that WHSV is carried out at operating conditions of 1-100 h- ¹ . 4. The method of converting carbon monoxide to C2 ₊ hydrocarbon according to any one of claims 1 to 3, wherein the silicon carbide foam is more than 50% by weight of β-type silicon carbide. A method for converting carbon oxides to C2 ₊ hydrocarbons. 5. The method for converting carbon monoxide to C ₂₊ hydrocarbons according to claim 1, wherein the content of the catalyst carrier is 50 wt% to substantially 100 wt% of β-type silicon carbide. %, Preferably substantially 100% by weight of β-type silicon carbide, converting carbon monoxide to C ₂₊ hydrocarbons. 6. The method of converting carbon monoxide to C2 ₊ hydrocarbons according to any one of claims 1 to 5, wherein the foam has a pore opening of 300 to 5000 [mu] m, preferably 1000 to 3000 [mu] m. A method for converting carbon monoxide into C ₂₊ hydrocarbons, characterized in that: The method for converting carbon monoxide to C ₂₊ hydrocarbons according to any one of claims 1 to 6, wherein the foam is a rigid foam, and the carbon monoxide is converted to C ₂₊ hydrocarbons. How to convert. The method for converting carbon monoxide to C ₂₊ hydrocarbons according to any one of claims 1 to 7, wherein the open porosity of the SiC foam is between 30% and 90%, in particular between 50% and 85%. A process for converting carbon monoxide to C ₂₊ hydrocarbons, characterized in that A method for converting carbon monoxide according to any one of claims 1 to 8 into C2 ₊ hydrocarbons, the method comprising:
-GHSV is 150-2000h < ^-1 >,
-A process for converting carbon monoxide to C2 ₊ hydrocarbons, characterized in that WHSV is carried out under operating conditions of 1 (preferably 5) to 50h- ¹ . A method of converting carbon monoxide according to any one of claims 1 to 9 into C2 ₊ hydrocarbons, the method comprising:
-The hydrocarbon productivity exceeds 3h ^-1 ,
A process for converting carbon monoxide to C2 ₊ hydrocarbons, characterized in that the productivity of C4 ₊ hydrocarbons is carried out under operating conditions in excess of 3h- ¹ . A method of converting carbon monoxide according to any one of claims 1 to 10 into C2 ₊ hydrocarbons, the method comprising:
-The hydrocarbon productivity is between 5 and 100 h,
A process for converting carbon monoxide to C2 ₊ hydrocarbons, characterized in that the productivity of C4 ₊ hydrocarbons is carried out at operating conditions between 5 and 50 h- ¹ . A method of converting carbon monoxide according to any one of claims 1 to 11 into C2 ₊ hydrocarbons, the method comprising:
-Total pressure: 10-100 atm,
-Reaction temperature: 160-260 ° C, preferably 160-250 ° C,
A process for converting carbon monoxide to C2 ₊ hydrocarbons, characterized in that it is carried out under operating conditions of an initial synthesis gas H ₂ / CO ratio of 1.2 to 2.8. A method of converting carbon monoxide according to any one of claims 1 to 12 into C2 ₊ hydrocarbons, the method comprising:
-Total pressure: 20-50 atm,
-Reaction temperature: 180-230 ° C
A process for converting carbon monoxide to C2 ₊ hydrocarbons, characterized in that it is carried out under operating conditions of an initial synthesis gas H ₂ / CO ratio of 1.7 to 2.3; 14. The method of converting carbon monoxide to C2 ₊ hydrocarbons according to any one of claims 1 to 13, wherein the reactor comprises a portion where the catalyst is supported on a carrier based on rigid silicon carbide foam, and A process for converting carbon monoxide to C2 ₊ hydrocarbons, characterized in that the catalyst has a part supported on a support in the form of granules or extrudates. 15. A method of converting carbon monoxide according to any one of claims 1 to 14 into C2 ₊ hydrocarbons, the method being performed upstream of the reactor. To convert C to C ₂₊ hydrocarbons. 15. A method of converting carbon monoxide according to any one of claims 1 to 14 into C2 ₊ hydrocarbons, the method being carried out downstream of the reactor. To convert C to C ₂₊ hydrocarbons. 17. A process for converting carbon monoxide to C2 ₊ hydrocarbons according to any one of claims 1 to 16, wherein the catalyst is 1 to 50% by weight, in particular 3 to 30% by weight, preferably 3 to 30% by weight. A process for converting carbon monoxide to C2 ₊ hydrocarbons, characterized in that it contains one or more metals from the group consisting of 20% by weight cobalt, iron and ruthenium. The method for converting carbon monoxide to C ₂₊ hydrocarbon according to any one of claims 1 to 17, wherein the catalyst is further Zr, K, Na, Mn, Sr, Cu, Cr, W, Re Carbon monoxide, characterized by having a promoter selected from the group consisting of Pt, Ir, Rh, Pd, Ru, Ta, V, Mo, and mixtures thereof, preferably Mo and Zr. Method to convert to ₂₊ hydrocarbons. 19. A process for converting carbon monoxide to C2 ₊ hydrocarbons according to any one of claims 1 to 18, wherein the reactor comprises more than 10, preferably more than 100 tubes, in particular 1000 to 100,000 tubes. A method for converting carbon monoxide to C2 ₊ hydrocarbons, characterized in that it is a multi-tube reactor. A method of converting carbon monoxide according to C ₂₊ hydrocarbons in any one of claims 1 to 18, pore size of the foam, the carbon monoxide, characterized in that inclined C ₂₊ hydrocarbons How to convert to hydrogen. 21. The method of converting carbon monoxide to C2 ₊ hydrocarbons according to any one of claims 1 to 20, wherein the foam is pulverized to convert carbon monoxide to C2 ₊ hydrocarbons. How to convert. 21. The method for converting carbon monoxide to C2 ₊ hydrocarbon according to any one of claims 1 to 20, wherein the reactor has a built-in heat exchanger. Method to convert to ₂₊ hydrocarbons. 23. A method of converting carbon monoxide according to any one of claims 1 to 22 into C2 ₊ hydrocarbons, comprising the step of improving the production of automobile fuel, wherein carbon monoxide is converted to C2 _+. Method to convert to hydrocarbon.