FR3050662A1 - COBALT CATALYST BASED ON A SUPPORT COMPRISING A MIXED OXIDE PHASE CONTAINING COBALT AND / OR NICKEL PREPARED BY USE OF AN AMINO ACID COMPOUND - Google Patents

Abstract

The subject of the invention is a catalyst containing an active phase of cobalt, deposited on a support comprising alumina, silica or silica-alumina, said support containing a mixed oxide phase containing cobalt and / or nickel, said catalyst was prepared by introducing at least one amino acid compound. The invention also relates to its use in the field of Fischer-Tropsch synthesis methods.

Description

The invention relates to a catalyst containing an active phase of cobalt, deposited on a support comprising alumina, silica or silica-alumina, said support containing a mixed oxide phase containing cobalt and / or nickel said catalyst has been prepared by introducing at least one amino acid compound. The invention also relates to its method of preparation and its use in the field of Fischer-Tropsch synthesis methods.

The present invention relates to the field of Fischer-Tropsch synthesis processes which make it possible to obtain a broad range of hydrocarbon cuts from the CO + H2 mixture, commonly called synthesis gas or syngas. The simplified stoichiometric equation (limited in the equation below to the formation of alkanes) of the Fischer-Tropsch synthesis is written:

n CO + (2n + 1) H2 -> CnH2n + 2 + n H2O

The catalysts used in Fischer-Tropsch synthesis are most often supported catalysts based on alumina, silica or silica-alumina or combinations of these supports, the active phase consisting mainly of iron (Fe) or cobalt ( Co) optionally doped with a noble metal such as Pt, Rh or Ru. The addition of an organic compound on Fischer-Tropsch catalysts to improve their activity has been recommended by those skilled in the art.

Many documents describe the use of different ranges of organic compounds as additives, such as organic compounds containing nitrogen and / or organic compounds containing oxygen.

In particular, patents US 5,856,260 and US 5,856,261 respectively teach the introduction, during the preparation of the catalyst, of polyols of general formula CnH2n + 20x with n an integer of between 2 and about 6, and X a integer between 2 and 11 or sugars of mono- or disaccharide type, sucrose being particularly preferred.

The patent application US 2005/0026776 teaches the use of nitrilotriacetic acid (NTA) chelating compounds, trans-1,2-cyclohexadiamine-Ν, Ν, Ν ', Ν' tetraacetic acid (CyDTA) or ethylenediaminetetraacetic acid (EDTA). ), or glycine, aspartic acid or citric acid to obtain a reduced size catalyst of crystallites CO 3 O 4. Other documents teach the use of polyethers (WO2014 / 092278 and WO2015 / 183061), glyoxylic acid (WO2015 / 183059), unsaturated dicarboxylic acids (US2011 / 0028575) or multifunctional carboxylic acids of formula HOOC - (CRR ^) n-COOH with n> 1 in the preparation of Fischer-Tropsch catalysts (WO98 / 47618).

The patent application US2014 / 0353213 describes the use of lactams or cyclic esters of lactone type containing an oxygen atom in the ring (β-propiolactone, γ-butyrolactone, δ-valerolactone) or several oxygen atoms in the cycle (propylene carbonate) to increase the activity of a CoMo or NiMo type catalyst used in hydrodesulfurization of a diesel cut.

US2005 / 0026776 discloses the use of amino acids as an additive of a Fischer-Tropsch catalyst based on a silica carrier having no mixed oxide phase containing cobalt and / or nickel.

WO2012 / 013866 discloses the use of a cyclic oligosaccharide, especially cyclodextrin, as additive of a Fischer-Tropsch catalyst. This document also describes the use of a silica-alumina support optionally containing a spinel.

However, none of the additive literature describes a cobalt-based catalyst deposited on a support containing a mixed oxide phase containing cobalt and / or nickel prepared using an amino acid compound.

Whatever the compounds chosen, the modifications induced do not always make it possible to increase sufficiently the performances of the catalyst in order to make the process profitable. In addition, it is often very complicated to proceed with their industrial deployment as the methods are complex to implement.

Therefore, it is essential for catalyst manufacturers to find new catalysts for improved performance Fischer-Tropsch synthesis. SUMMARY The invention relates to a catalyst containing an active phase of cobalt, deposited on a support comprising alumina, silica or silica-alumina, said support containing a mixed oxide phase containing cobalt and / or or nickel, said catalyst being prepared by a process comprising at least: a) a step of contacting a support comprising alumina, silica or silica-alumina with at least one solution containing at least a precursor of cobalt and / or nickel, and then dried and calcined at a temperature between 700 and 1200 ° C, so as to obtain a mixed oxide phase containing cobalt and / or nickel in the support, then performs b) a step of contacting said support containing said mixed oxide phase with at least one solution containing at least one cobalt precursor, c) a step of contacting said support containing said mixed oxide phase with less an acid compound amine, steps b) and c) can be performed separately, in any order, or simultaneously, d) and then performs a drying step at a temperature below 200 ° C.

The applicant has indeed found that the use of an amino acid compound as an organic additive during the preparation of a catalyst containing an active phase of cobalt, deposited on a support comprising alumina, silica or silica-alumina, said support also containing a mixed oxide phase containing cobalt and / or nickel provided a catalyst for Fischer-Tropsch synthesis showing improved catalytic performance.

Indeed, the catalyst according to the invention shows an increased activity and selectivity compared to catalysts containing a mixed oxide phase containing cobalt and / or nickel in their support but prepared without additivation or with respect to catalysts with additives containing no no mixed oxide phase containing cobalt and / or nickel in the support. The use of such an organic compound during the preparation of a cobalt-containing catalyst containing a support containing a mixed oxide phase containing cobalt and / or nickel appears to have a synergistic effect on activity and selectivity in a Fischer-Tropsch process.

Without being bound by any theory, it has been discovered that such a catalyst has a substantially greater cobalt dispersion than that exhibited by catalysts prepared in the absence of such an organic compound. This results in the presence of a greater number of active sites for the catalysts prepared in the presence of at least one amino acid compound, even if this amino acid compound is at least partially subsequently removed by drying and possibly calcination. .

According to one variant, the mixed oxide phase content in the support is between 0.1 and 50% by weight relative to the weight of the support.

According to one variant, the mixed oxide phase comprises an aluminate of formula COAl 2 O 4 or NiAl 2 O 4 in the case of a support based on alumina or silica-alumina.

According to one variant, the mixed oxide phase comprises a silicate of formula Co 2 SiO 4 or Ni 2 SiO 4 in the case of a support based on silica or silica-alumina. According to one variant, the silica content of said support is between 0.5% by weight and 30% by weight relative to the weight of the support before the formation of the mixed oxide phase when the support is a silica-alumina.

According to one variant, the amino acid compound introduced during stage c) is an α-amino acid.

According to this variant, the amino acid compound is chosen from glycine, proline or lysine.

According to one variant, the molar ratio of amino acid compound introduced during step c) with respect to the cobalt element introduced in step b) is between 0.01 and 2.0 mol / mol.

According to one variant, the content of cobalt element introduced during step b) as active phase is between 2 and 40% by weight expressed as metallic cobalt element relative to the total weight of the catalyst.

Alternatively, the catalyst further comprises a member selected from groups VIIIB, IA, IB, IIA, IIB, IIIA, IIIB and VA.

Alternatively, the catalyst further contains an organic compound other than the amino acid compound, said organic compound containing oxygen and / or azote.

According to this variant, the organic compound is chosen from a compound comprising one or more chemical functional groups chosen from a carboxylic function, alcohol, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide.

According to a variant, after the drying step d), a calcination step e) is carried out at a temperature of between 200 and 550 ° C. under an inert atmosphere or under an atmosphere containing oxygen.

According to one variant, the catalyst obtained in the drying step d) or obtained in the calcining step e) is reduced to a temperature of between 200 ° C. and 500 ° C. The invention also relates to the use of the catalyst according to the invention in a Fischer-Tropsch synthesis process in which the catalyst according to the invention is brought into contact with a feedstock comprising synthesis gas at a total pressure of between 0.degree. 1 and 15 MPa, at a temperature of between 150 and 350 ° C., and at an hourly space velocity of between 100 and 20000 volumes of synthesis gas per volume of catalyst and per hour, with a molar ratio of H2 / CO of the synthesis gas. between 0.5 and 4.

In the following, groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC press, editor-in-chief DR üde, 81 ^ "'® edition, 2000-2001). group VIII according to the classification CAS corresponds to the metals of columns 8, 9 and 10 according to the new classification LUPAC.

The textural and structural properties of the support and the catalyst described below are determined by the characterization methods known to those skilled in the art. The total pore volume and the porous distribution are determined in the present invention by nitrogen porosimetry as described in the book "Adsorption by powders and porous solids. Principles, methodology and applications "written by F. Rouquérol, J. Rouquérol and K. Sing, Academie Press, 1999.

By specific surface is meant the BET specific surface area (Sbet in m 2 / g) determined by nitrogen adsorption according to the ASTM D 3663-78 standard established from the BRUNAUER-EMMETT-TELLER method described in the "The Journal of American Society, 1938, 60, 309.

Detailed description of the invention

The catalyst according to the invention is a catalyst containing an active phase of cobalt, deposited on a support comprising alumina, silica or silica-alumina, said support containing a mixed oxide phase containing cobalt and / or or nickel, said catalyst being prepared by a process comprising at least: a) a step of contacting a support comprising alumina, silica or silica-alumina with at least one solution containing at least a precursor of cobalt and / or nickel, then dried and calcined at a temperature between 700 and 1200 ° C, so as to obtain a mixed oxide phase containing cobalt and / or nickel in the support. then b) a step of contacting said support containing said mixed oxide phase with at least one solution containing at least one cobalt precursor, c) a step of contacting said support containing said mixed oxide phase with at least one amino acid compound, steps b) and c) can be carried out separately, in any order, or simultaneously, d) and then a drying step is carried out at a temperature below 200 ° C.

The various steps of the process leading to the catalyst according to the invention will be detailed later;

Step a) Formation of the mixed oxide phase containing cobalt and / or nickel The objective of step a) is the formation of a mixed oxide phase containing cobalt and / or nickel in a support comprising alumina, silica or silica-alumina by contacting a solution containing at least one precursor of cobalt and / or nickel, followed by drying and calcining at high temperature .

It is known that the presence of a mixed oxide phase containing cobalt and / or nickel in a support of the alumina, silica or silica-alumina type makes it possible to improve the resistance to the phenomenon of chemical and mechanical attrition in a Fischer-Tropsch process, and thus to stabilize the support.

The formation of the mixed oxide phase in the support, often called the stabilization step of the support, can be carried out by any method known to those skilled in the art. It is generally carried out by introducing cobalt and / or nickel in the form of a salt precursor, for example of the nitrate type, onto the initial support containing alumina, silica or silica-alumina. By calcination at a very high temperature, the mixed oxide phase containing cobalt and / or nickel is formed and stabilizes the entire support. The cobalt and / or nickel contained in the mixed oxide phase is not reducible during the final activation of the Fischer-Tropsch catalyst (reduction). The cobalt and / or nickel contained in the mixed oxide phase does not therefore constitute the active phase of the catalyst.

According to step a), a step is performed to bring a support comprising alumina, silica or silica-alumina into contact with at least one solution containing at least one precursor of cobalt and / or nickel. then dried and calcined at a temperature between 700 and 1200 ^ 0, so as to obtain a mixed oxide phase containing cobalt and / or nickel in the support.

More particularly, the step a) of contacting can be carried out by impregnation, preferably dry, of a support comprising alumina, silica or silica-alumina, preformed or in powder form, with minus an aqueous solution containing the precursor cobalt and / or nickel, followed by drying and calcination at a temperature between 700 and 1200 ° C.

The cobalt is brought into contact with the support via any soluble cobalt precursor in the aqueous phase. Preferably, the cobalt precursor is introduced in aqueous solution, preferably in the form of nitrate, carbonate, acetate, chloride, complexes formed with acetylacetonates, or any other soluble inorganic derivative in aqueous solution, which is brought into contact with said support. The cobalt precursor advantageously used is cobalt nitrate or cobalt acetate.

The nickel is brought into contact with the support via any soluble nickel precursor in the aqueous phase. Preferably, said nickel precursor is introduced in aqueous solution, for example in the form of nitrate, carbonate, acetate, chloride, hydroxide, hydroxycarbonate, oxalate, complexes formed with acetylacetonates, or any other soluble inorganic derivative in aqueous solution, which is contacted with said support. The nickel precursor advantageously used is nickel nitrate, nickel chloride, nickel acetate or nickel hydroxycarbonate.

The total content of cobalt and / or nickel is advantageously between 1 and 20% by weight and preferably between 2 and 10% by weight relative to the weight of the final support.

The drying is advantageously carried out at a temperature of between 60 ° C. and 200 ° C., preferably for a period ranging from 30 minutes to three hours.

The calcination is carried out at a temperature of between 700 and 1200 ° C., preferably between 850 and 1200 ° C., and preferably between 850 and 900 ° C., generally for a period of between one hour and 24 hours, and preferably between 2 hours and 5 hours. The calcination is generally carried out under an oxidizing atmosphere, for example under air, or under oxygen-depleted air; it can also be carried out at least partly under nitrogen. It makes it possible to transform cobalt and / or nickel precursors and alumina and / or silica in the mixed oxide phase containing cobalt and / or nickel.

According to one variant, the calcination can also be carried out in two stages, said calcination is advantageously carried out at a temperature of between 300X and 600 ° C. under air for a period of between half an hour and three hours, and then at a temperature between 700 ° C and 1200 ° C, preferably between 850 and 1200 ° C and preferably between 850 and OOO'X, generally for a period of between one hour and 24 hours, and preferably between 2 hours and 5 hours .

The support comprises alumina, silica or silica-alumina.

When the support comprises alumina, it contains more than 50% by weight of alumina relative to the weight of the support before the formation of the mixed oxide phase and, preferably, it contains only alumina. The alumina may be present in a crystallographic form of alumina gamma, delta, theta, alpha, taken alone or in melanige.

In another preferred case, the support comprises silica. In this case, it contains more than 50% by weight of silica relative to the weight of the support before the formation of the mixed oxide phase and, preferably, it contains only silica. Silicon sources are well known to those skilled in the art.

In another preferred case, the support comprises a silica-alumina. By a support comprising a silica-alumina is meant a support in which the silicon and the aluminum is in the form of agglomerates of silica or alumina respectively, of amorphous aluminosilicate or any other mixed phase containing silicon and aluminum. aluminum, it being understood that the support is not mesostructured. Preferably, the alumina and the silica are present in the form of a mixture of SiOa-AbOa oxides. The silica content in the silica-alumina support ranges from 0.5% by weight to 30% by weight, preferably from 1% by weight to 25% by weight, and even more preferably from 1.5 to 20% by weight relative to the weight of the support before the formation of the mixed oxide phase.

According to a preferred variant, the support consists of alumina, silica or silica-alumina, and particularly preferably the support consists of silica-alumina.

The support also contains a mixed oxide phase containing cobalt and / or nickel. Mixed oxide phase containing cobalt and / or nickel is understood to mean a phase in which cobalt and / or nickel cations are combined with the oxide ions O '' of the alumina and / or silica support thus a mixed phase containing aluminates and / or silicates containing cobalt and / or nickel. The mixed oxide phase may be in amorphous form or in crystallized form.

When the support is based on alumina, the mixed oxide phase can comprise an aluminate of formula C0Al2O4 or ΝΙΑΐ2θ4, in amorphous or crystallized form, for example in spinel form.

When the support is based on silica, the mixed oxide phase may comprise a silicate of formula Co 2 SiO 4 or Ni 2 SiO 4 (cobalt or nickelorthosilicate), in amorphous or crystalline form.

When the support is based on silica-alumina, the mixed oxide phase can comprise an aluminate of formula C0Al2O4 or NiAl204, in amorphous or crystallized form, for example in spinel form, and / or a silicate of formula Co2SiO4 or Ni2SiO4, in amorphous or crystalline form. Generally, the content of the mixed oxide phase in the support is between 0.1 and 50% by weight relative to the weight of the support, preferably between 0.5 and 30% by weight, and more preferably between 1 and 20% weight

The presence of mixed oxide phase in the catalyst according to the invention is measured by programmed temperature reduction RTP (or TPR for "programmed temperature reduction" according to the English terminology) such as for example described in 0/7 & Gas Science and Technology, Rev. IFP, Vol. 64 (2009), No. 1, pp. 11-12 According to this technique, the catalyst is heated under a flux of a reducing agent, for example under a flow of dihydrogen.The measurement of the dihydrogen consumed as a function of the temperature gives information The presence of a mixed oxide phase in the catalyst is thus manifested by a consumption of dihydrogen at a temperature greater than about δΟΟ'Ό.

The support may have a morphology in the form of beads, extrudates (for example of trilobed or quadrilobic form) or pellets, especially when said catalyst is used in a reactor operating in fixed bed, or have a morphology in the form of variable particle size powder, especially when said catalyst is used in a bubble column type reactor (or "siurry bubble column" according to the English termination). The size of the catalyst grains may be between a few microns and a few hundred microns. For an implementation in "siurry" reactor, the particle size of the catalyst is preferably between 10 microns and 500 microns, preferably between 10 microns and 300 microns, very preferably between 20 and 200 microns, and so even more preferred between 30 and 160 microns.

The specific surface of the support containing the mixed oxide phase is generally between 50 m 2 / g and 500 m 2 / g, preferably between 100 m 2 / g and 300 m 2 / g, more preferably between 150 m 2 / g and 500 m 2 / g. ^ / g and 250 ^ / g. The pore volume of said support is generally between 0.3 ml / g and 1.2 ml / g, and preferably between 0.4 ml / g and 1 ml / g.

Thus, after said step a), said support comprising alumina, silica or silica-alumina further comprises a mixed oxide phase containing cobalt and / or nickel.

Step b) and c): Introduction of the active phase and the amino acid compound

After the formation of the mixed oxide phase, the following steps are carried out in the preparation of the catalyst according to the invention; b) a step of contacting said support containing said mixed oxide phase with at least one solution containing at least one cobalt precursor, c) a step of contacting said support containing said mixed oxide phase with at least one an amino acid compound, the steps b) and c) can be performed separately, in any order, or simultaneously. Step b) bringing said support into contact with at least one solution containing at least one cobalt precursor can be carried out by any method that is well known to a person skilled in the art. Said step b) is preferably carried out by impregnation of the support with at least one solution containing at least one cobalt precursor. In particular, said step b) can be carried out by dry impregnation, by excess impregnation, or by precipitation deposition (as described in US Pat. Nos. 5,874,381 and 6,534,436) according to methods that are well known in the art. 'Man of the trade. Preferably, said step b) is carried out by dry impregnation, which consists in bringing the catalyst support into contact with a solution containing at least one cobalt precursor whose volume is equal to the pore volume of the support to be impregnated. This solution contains the cobalt precursor at the desired concentration.

The cobalt is brought into contact with said support via any soluble cobalt precursor in the aqueous phase or in the organic phase. When introduced in organic solution, said cobalt precursor is, for example, cobalt acetate. Preferably, said cobalt precursor is introduced in aqueous solution, for example in the form of nitrate, carbonate, acetate, chloride, complexes formed with acetylacetonates, or any other soluble inorganic derivative in aqueous solution, which is brought into contact with said support. Cobalt precursor is advantageously cobalt nitrate or cobalt acetate.

The content of cobalt element is between 2 and 40% by weight, preferably between 5 and 30% by weight, and more preferably between 10 and 25% by weight expressed as cobalt metal element relative to the total weight of the catalyst.

The catalyst may advantageously furthermore comprise at least one element selected from a group VIIIB, IA, IB, IIA, IIB, IIIA, IIIB and / or VA element.

The possible elements of the group VIIIB that are preferred are platinum, ruthenium and rhodium. The preferred group IA elements are sodium and potassium. The preferred group IB elements are silver and gold. The preferred group IIA elements are manganese and calcium. The element of the preferred MB group is zinc. The preferred IIIA group elements are boron and indium. Preferred group IIIB elements are lanthanum and cerium. The preferred VA group element is phosphorus.

The optional element content of the groups VIIIB, IA, IB, IIA, MB, IIIA, IIIB and / or VA is between 50 ppm and 20% by weight, preferably between 100 ppm and 15% by weight, and more preferably between 100 ppm and 10% weight expressed as element relative to the total weight of the catalyst.

According to a variant, when the catalyst contains one or more additional elements of groups VIIIB, IA, IB, IIA, IIB, IIIA, IIIB and / or VA, this or these elements may be either initially present on the support before the preparation of the catalyst, is introduced at any time of the preparation and by any method known to those skilled in the art.

The contacting of the organic compound employed for the implementation of said step c) with said support is carried out by impregnation, in particular by dry impregnation or excess impregnation, preferably by dry impregnation. Said organic compound is preferably impregnated on said support after solubilization in aqueous solution.

Said amino acid compound comprises at least one carboxylic acid functional group and an amine functional group. It is called α-amino acid, β-amine, γ-amino, δ-amino according to the carbon atom on which the amine functional group is located. Preferably the compound is an α-amino acid. Among the α-amino acids, the organic compound may be chosen from the following compounds: alanine, argiriine, asparagine, aspartic acid, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine. When the compound is an α-amino acid, it is preferably selected from glycine, proline and lysine.

The molar ratio of amino acid compound introduced during step c) relative to the cobalt element introduced in step b) is between 0.01 and 2.0 mol / mol, preferably between 0, 05 and 1.0.

The catalyst according to the invention may comprise, in addition to the amino acid compound, another organic compound or a group of organic compounds known for their role as additives. The function of the additives is to increase the catalytic activity compared to the non-additive catalysts. More particularly, the catalyst according to the invention may further comprise one or more organic compounds containing oxygen and / or nitrogen. Generally, the organic compound is chosen from a compound comprising one or more chemical functional groups chosen from a carboxylic function, alcohol, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide.

The oxygen-containing organic compound may be one or more selected from compounds having one or more chemical functions selected from a carboxylic, alcohol, ether, aldehyde, ketone, ester or carbonate function. For example, the organic oxygen-containing compound may be one or more selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (with a molecular weight between 200 and 1500 g mol), propylene glycol, 2-butoxyethanol, 2- (2-butoxyethoxy) ethanol, 2- (2-methoxyethoxy) ethanol, triethylene glycol dimethyl ether, glycerol, acetophenone, 2,4-pentanedione, pentanone, acetic acid, maleic acid, malic acid, malonic acid, malic acid, oxalic acid, gluconic acid, tartaric acid, citric acid, succinic acid, γ-ketovaleric acid, γ-valerolactone, 4-hydroxyvaleric acid, 2-pentenoic acid, 3-pentenoic acid, 4-pentenoic acid, C1-C4 dialkyl succinate, methyl acetoacetate, a lactone, dibenzofuran, a crown ether, orthophthalic acid eu, glucose and propylene carbonate.

The nitrogen-containing organic compound may be one or more selected from compounds having one or more chemical functions selected from an amine or nitrile function. By way of example, the nitrogen-containing organic compound may be one or more selected from the group consisting of ethylenediamine, diethylenetriamine, hexamethylenediamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, acetonitrile octylamine, guanidine or carbazole.

The organic compound containing oxygen and nitrogen may be one or more chosen from compounds comprising one or more chemical functional groups chosen from a carboxylic acid, alcohol, ether, aldehyde, ketone, ester, carbonate or amine function. nitrile, imide, amide, urea or oxime. By way of example, the organic compound containing oxygen and nitrogen may be one or more selected from the group consisting of 1,2-cyclohexanediaminetetraacetic acid, monoethanolamine (MEA), N- methylpyrrolidone, dimethylformamide, ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), N- (2-hydroxyethyl) ethylenediamine-Ν, Ν ', Ν'-triacetic acid (HEDTA), diethylene acid -triaminepentaacétique (DTPA), tetramethylurea, dimethylglyoxime, bicine or tricine, or a lactam.

The total molar ratio of organic compound (s) containing oxygen and / or nitrogen other than the amino acid compound relative to the cobalt element introduced in step b) is between 0 , 01 to 2 mol / mol, preferably between 0.01 to 2 mol / mol, preferably between 0.02 and 1.5 mol / mol, calculated on the basis of the components introduced into the solution (s) ( s) impregnation.

When the catalyst further contains an organic compound other than the amino acid compound, this organic compound may be either initially present on the support before the preparation of the catalyst, or incorporated into the catalyst at any time of the preparation and by any method known to those skilled in the art.

Implementation of Steps b) and c)

The process for preparing the catalyst according to the invention, in particular steps b) and c) comprises several modes of implementation. They are distinguished in particular by the moment of the introduction of the organic compound which can be carried out either at the same time as the impregnation of cobalt of the active phase (co-impregnation), or after the impregnation of cobalt of the active phase (post-impregnation) before cobalt impregnation of the active phase (pre-impregnation). In addition, the modes of implementation can be combined.

A first embodiment consists of performing said steps b) and c) simultaneously so that said organic compound and at least said cobalt precursor present in the active phase are co-impregnated on said support (co-impregnation). . Said first embodiment advantageously comprises the implementation of one or more steps b). In particular, one or more steps b) precedes (nt) and / or follows (nt) advantageously said co-impregnation step. Said first embodiment may comprise several steps of co-impregnation.

A second embodiment consists of performing said step b) prior to said step c) (post-impregnation). According to said second embodiment, one or more steps b) of contacting at least cobalt present in the active phase of the catalyst precedes (s) said step c).

A third mode of implementation consists in performing said step c) prior to said step b) (pre-impregnation). Advantageously, said step c) is followed by several steps b).

When steps b) and c) are carried out separately (post-impregnation or pre-impregnation), a drying step is advantageously carried out between the impregnation steps. The intermediate drying step is carried out at a temperature below 200 ° C., advantageously between 50 and 180 ° Ό, preferably between 70 and 150 ° C., very preferably between 75 and 130 ° C. and optionally a period of maturation was observed between the impregnation step and the intermediate drying step.

Each of the three implementation modes described above can be carried out independently so that the catalyst according to the invention is prepared either according to said first embodiment, or according to said second implementation mode is according to said third embodiment. However, it may be advantageous to associate said first mode with said second mode or with said third mode; both the cobalt present in the active phase and the organic compound are deposited at least twice on the catalyst support, namely at least once by co-impregnation and at least once by successive impregnation.

Advantageously, after each impregnation step, whether it is a step of impregnating the cobalt or the organic compound, the impregnated support is allowed to mature. The maturation allows the impregnating solution to disperse homogeneously within the support.

Any maturation step described in the present invention is advantageously carried out at atmospheric pressure, in an atmosphere saturated with water and at a temperature of between 17 ° C. and 50 ° C., and preferably at ambient temperature. Generally a ripening time of between ten minutes and forty-eight hours and preferably between thirty minutes and five hours, is sufficient. Longer durations are not excluded, but do not necessarily improve.

Any impregnation solution described in the present invention may comprise any polar solvent known to those skilled in the art. Said polar solvent used is advantageously chosen from the group formed by methanol, ethanol, water, phenol and cyclohexanol, taken alone or as a mixture. Said polar solvent can also be advantageously chosen from the group formed by propylene carbonate, DMSO (dimethylsulfoxide), N-methylpyrrolidone (NMP) or sulfolane, alone or as a mixture. Preferably, a polar protic solvent is used. A list of the usual polar solvents as well as their dielectric constant can be found in the book Solvents and Solvent Effects in Organic Chemistry (C. Reichardt, Wiley-VCH, 3rd edition, 2003, pages 472-474. Very preferably, the solvent used is water or ethanol, and particularly preferably, the solvent is water. In one possible embodiment, the solvent may be absent in the impregnating solution.

When carrying out several impregnation steps, each impregnation step is preferably followed by an intermediate drying step at a temperature below 200 ° C., advantageously between 50 and 180 ° C., preferably between 70 and 150 ° C. ° C, very preferably between 75 and 130 ° C and optiônally a period of maturation was observed between the impregnation step and the intermediate drying step.

Step d) drying

According to the drying step d) of the implementation for the preparation of the catalyst, prepared according to at least one embodiment described above, the drying is carried out at a temperature below 200 ° C, advantageously included between 50 and 180 ° C, preferably between 70 and 150 ° C, very preferably between 75 and 130 ° C. The drying step is preferably carried out for a period of between 1 and 4 hours, preferably under an inert atmosphere or under an atmosphere containing oxygen. The drying step may be performed by any technique known to those skilled in the art. It is advantageously carried out at atmospheric pressure or under reduced pressure. Preferably, this step is carried out at atmospheric pressure. It is advantageously carried out in crossed bed using air or any other hot gas. Preferably, when the drying is carried out in a fixed bed, the gas used is either air or an inert gas such as argon or nitrogen. Very preferably, the drying is carried out in a bed traversed in the presence of nitrogen and / or air. Preferably, the drying step has a short duration of between 5 minutes and 4 hours, preferably between 30 minutes and 4 hours and very preferably between 1 hour and 3 hours.

According to a first variant, the drying is carried out so as to preferably retain at least 30% of the introduced amino acid compound during an impregnation step, preferably this amount is greater than 50% and even more preferably greater than at 70%, calculated on the basis of the carbon remaining on the catalyst. When an organic compound containing oxygen and / or nitrogen other than the amino acid compound is present, the drying step is carried out so as to preferably retain at least 30%, preferably at least 50% and most preferably at least 70% of the feed amount calculated on the basis of the carbon remaining on the catalyst. At the end of the drying step d), a dried catalyst is then obtained, which will be subjected to an activation step for its subsequent implementation in Fischer-Tropsch synthesis.

According to another variant, at the end of step d) of drying, a calcination step e) is carried out at a temperature of between 200 ° C. and 550 ° C., preferably between 250 ° C. and 500 ° C. under an inert atmosphere (nitrogen for example) or an atmosphere containing oxygen (air for example). The duration of this heat treatment is generally between 0.5 hours and 16 hours, preferably between 1 hour and 5 hours. After this treatment, the cobalt of the active phase is thus in oxide form and the catalyst contains no more or very little organic compound introduced during its synthesis. However, the introduction of the organic compound during its preparation has made it possible to increase the dispersion of the active phase thus leading to a more active and / or more selective catalyst.

Activation (Reduction)

Prior to its use in the catalytic reactor and the implementation of the Fischer-Tropsch process according to the invention, the dried catalyst obtained in step d) or the calcined catalyst obtained in step e) advantageously undergoes a reducing treatment, for example with hydrogen, pure or diluted, at high temperature. This treatment activates said catalyst and form metal cobalt particles in the zero state valent. The temperature of this reducing treatment is preferably between 200 and 500 ° C and its duration is between 2 and 20 hours.

This reducing treatment is carried out either in situ (in the same reactor as that where the Fischer-Tropsch reaction is carried out according to the process of the invention), or ex situ before being loaded into the reactor.

Fischer-Tropsch process

Finally, another subject of the invention is the use of the catalyst according to the invention in a Fischer-Tropsch synthesis process.

The Fischer-Tropsch process according to the invention leads to the production of essentially linear and saturated hydrocarbons C5 + (having at least 5 carbon atoms per molecule). The hydrocarbons produced by the process of the invention are thus essentially paraffinic hydrocarbons, the fraction having the highest boiling points can be converted with a high yield of middle distillates (gasoil and kerosene cuts) by a process of hydroconversion such as hydrocracking and / or catalytic hydroisomerization (s).

The charge used for the implementation of the process of the invention comprises synthesis gas. The synthesis gas is a mixture comprising, in particular, carbon monoxide and hydrogen having H 2 / CO molar ratios which can vary in a ratio of from 0.5 to 4 depending on the process by which it has been obtained. The molar ratio H2 / CO of the synthesis gas is generally close to 3 when the synthesis gas is obtained from the process of steam reforming hydrocarbons or alcohol. The molar ratio H2 / CO of the synthesis gas is of the order of 1.5 to 2 when the synthesis gas is obtained from a partial oxidation process. The molar ratio H2 / CO of the synthesis gas is generally close to 2.5 when it is obtained from a thermal reforming process. The molar ratio H2 / CO of the synthesis gas is generally close to 1 when it is obtained from a gasification and reforming process of CO2.

The catalyst used in the hydrocarbon synthesis process according to the invention can be used in different types of reactors, for example in a fixed bed, in a molten bed, in a bubbling bed or in a three-phase fluidized bed. The use of the catalyst in suspension in a three-phase fluidized reactor, preferably of the bubble column type, is preferred. In this preferred implementation of the catalyst, said catalyst is divided into a state of very fine powder, particularly of the order of a few tens of microns, this powder forming a suspension with the reaction medium. This technology is also known under the terminology of "siurry" process by the skilled person.

The hydrocarbon synthesis process according to the invention is carried out under a total pressure of between 0.1 and 15 MPa, preferably between 0.5 and 10 MPa, at a temperature of between 150 and 350 ° C., preferably between 180 and 270 ° C. The hourly volume velocity is advantageously between 100 and 20000 volumes of synthesis gas per volume of catalyst and per hour (100 to 20000 h -1) and preferably between 400 and 10,000 volumes of synthesis gas per volume of catalyst and per hour. (400 to 10,000 hours).

The following examples demonstrate the performance gains on the catalysts according to the invention.

Examples

Example 1 (Comparative) Catalyst A of Formula C0 / Al2O3

A catalyst A comprising cobalt deposited on an alumina support is prepared by dry impregnation of an aqueous solution of cobalt nitrate so as to deposit in two successive steps of the order of 10% by weight of Co on a powder of gamma alumina (PURALOX® SCCa 5/170, SASOL) with a mean particle size of 80 μm, a surface area of 165 m 2 / g and a pore volume measured by nitrogen adsorption isotherm at 0.4 ml / g.

After a first dry impregnation, the solid is dried in a bed passed through at 120 ° C. for 3 hours in air and then calcined at 400 ° C. for 4 hours in a bed traversed under a stream of air. The intermediate catalyst contains about 6% by weight of Co. It is subjected to a second dry impregnation step using a solution of cobalt nitrate. The solid obtained is dried in a bed passed through at 120 ° C. for 3 hours in air and then calcined at 400 ° C. for 4 hours in a bed traversed under a stream of air. The final catalyst A which contains 10.5% by weight of Co (in the form of CO 3 O 4 oxide) is obtained.

Example 2 (Comparative) Catalyst B of Formula Co / AI203.SIO2

A catalyst B comprising cobalt deposited on a silica-alumina support is prepared by dry impregnation of an aqueous solution of cobalt nitrate so as to deposit in one step approximately 10% by weight of Co on a silica-alumina initially containing 5 % weight of SiO 2 and having a specific surface area of 180 m 2 / g and a pore volume of 0.8 ml / g).

After dry impregnation, the solid is dried in a bed passed through at 120 ° C. for 3 hours in air and then calcined at 400 ° C. for 4 hours in a traversed bed. The final catalyst B which contains 9.9% by weight of Co (in the form of CO 3 O 4 oxide) is obtained.

Example 3 (Comparative) Catalyst C of Formula Co / CoAl 2 O 4 -Al 2 O 3 -SiO 2

A catalyst C comprising cobalt deposited on a support, based on mixed oxide phase (in the form of spinel) included in a silica-alumina, is prepared by dry impregnation of an aqueous solution of cobalt nitrate so as to deposit in one step about 10% weight of cobalt on the support.

The spinel present in the catalyst support C is a simple spinel formed of cobalt aluminate, which is included in a silica-alumina containing 5% by weight of SiOa, and having a specific surface area of 180 m 2 / g and a pore volume. 0.8 ml / g. The preparation of the spinel included in the silica-alumina is carried out by dry impregnation of an aqueous solution of cobalt nitrate so as to introduce 5% by weight of Co in said silica-alumina. After drying at 120 ° C for 3 hours, the solid is calcined at 850 ° C for 4 hours in air. The support of the catalyst denoted C 'is formed of 5% by weight of cobalt in the form of cobalt aluminate (ie 15% by weight of spinel) in the silica-aluminum.

The active phase based on cobalt is then deposited on said support in one step, by dry impregnation, according to a protocol identical to that described for the preparation of catalyst B. The drying and calcination steps are also performed under the same conditions The concentration of cobalt in the cobalt nitrate solution, used for the successive impregnations, is chosen to obtain the catalyst C with the desired final Co content.

The final catalyst C has a total cobalt content of 15.7% by weight (the content of Co present in the spinel phase being included) and a cobalt content in the form of CO 3 O 4 oxide of 10.7% by weight.

Example 4 (comparative): Catalyst D of formula Co / COAl 2 O 4 -Al 2 O 3 SiO 2 containing citric acid.

A catalyst D comprising cobalt and citric acid deposited on a support, based on a spinel included in a silica-alumina, is prepared by dry impregnation of an aqueous solution of cobalt nitrate, followed by aqueous solution of citric acid so as to deposit about 10% by weight of cobalt on the support.

The active phase based on cobalt is deposited on the support C 'of Example 3 in one step, by dry impregnation of a solution containing cobalt nitrate. After the dry impregnation, the solid undergoes drying in a bed. crossed at 120 ° C for 3 hours in air.

In a second step, the citric acid is deposited on the above solid in one step, by dry impregnation of a solution containing citric acid (Sigma Aldrich®,> 99%) at a concentration which makes it possible to reach a molar ratio on the final catalyst citric acid: Co 0.5. After the dry impregnation, the solid is matured in a saturated water atmosphere for 9 hours at room temperature, then is dried in a bed passed through at 120 ° C. for 3 hours in air and then treated under nitrogen at 400 ° C. for 4 hours in crossed bed. \

The final catalyst D has a total cobalt content of 14.0% by weight (the content of Co present in the spinel phase being included) and a cobalt content in the form of CO 3 O 4 oxide of 9.0% by weight.

Example 5 (According to the Invention): Catalyst E of Formula Co / CoAl 2 O 4 -Al 2 O 3 SiO 2 Containing Iysine

A catalyst E comprising cobalt and lysine deposited on a support, based on a spinel included in a silica-alumina, is prepared by dry impregnation with an aqueous solution of cobalt nitrate, then with an aqueous solution of lysine so as to deposit about 10% by weight of cobalt on the support.

The active phase based on cobalt is deposited on the support C 'of Example 3 in one step, by dry impregnation of a solution containing cobalt nitrate. After the dry impregnation, the solid undergoes drying in a bed. crossed at 120 ^ 0 for 3 hours in air.

In a second step, the lysine is deposited on the above solid in one step, by dry impregnation of a solution containing lysine (Sigma Aldrich®,> 98%) at a concentration making it possible to reach a molar ratio on the final lysine catalyst; Co of 0.1. After the dry impregnation, the solid is matured in a saturated water atmosphere for 9 hours at room temperature, then is dried in a bed passed through at 120 ° C. for 3 hours in air and then treated under nitrogen at 400 ° C. for 4 hours in crossed bed.

The final catalyst E has a total cobalt content of 14.9% by weight (the content of Co present in the spinel phase being included) and a cobalt content in the form of CO 3 O 4 oxide of 9.9% by weight.

Example 6 (according to the invention); Catalyst F of the formula Co / COAl 2 O 4 -Al 2 O 3 SiO 2 containing proline.

A catalyst F comprising cobalt and proline deposited on a support, based on a spinel included in a silica-alumina, is prepared by dry impregnation of an aqueous solution of cobalt nitrate and proline so as to deposit about 10% weight of cobalt on the support.

The active phase based on cobalt is deposited on the support C 'of Example 3 in one step, by dry impregnation of a solution containing cobalt nitrate and DL-Proline (Sigma Aldrich®, 99%) at a concentration which makes it possible to reach a molar ratio on the final proline: Co catalyst of 0.1. After the dry impregnation, the solid undergoes drying in a bed passed through at 120 ° C. for 3 hours in air and then treated under nitrogen at 400 ° C. for 4 hours in a crossed bed.

The final catalyst F has a total cobalt content of 15.2% by weight (the content of Co present in the spinel phase being included) and a cobalt content in the form of CO 3 O 4 oxide of 10.2% by weight.

Example 7 (according to the invention) Catalyst G of formula Co / COAl 2 O 4 -Al 2 O 3 SO 2 containing glycine.

A catalyst G comprising cobalt and glycine deposited on a support, based on a spinel included in a silica-alumina, is prepared by dry impregnation with an aqueous solution of cobalt nitrate, then with an aqueous solution of glycine so as to deposit about 10% by weight of cobalt on the support.

The active phase based on cobalt is deposited on the support C 'of Example 3 in one step, by dry impregnation of a solution containing cobalt nitrate. After the dry impregnation, the solid undergoes drying in a bed. crossed at 120X for 3 hours in the air.

In a second step, the glycine is deposited on the above solid in one step, by dry impregnation of a solution containing glycine (Sigma Aldrich®,> 99%) at a concentration making it possible to reach a molar ratio on the final catalyst lysine: Co of 1. After the dry impregnation, the solid is matured in a saturated atmosphere of water for 9 hours at room temperature, then is dried in a bed passed through at 120 ° C for 3 hours in air, and then treated under nitrogen at 400 ° C for 4h in crossed bed.

The final catalyst G has a total cobalt content of 14.3% by weight (the content of Co present in the spinel phase being included) and a cobalt content in the form of CO 3 O 4 oxide of 9.3% by weight.

Example 8 (according to the invention) Catalyst H of formula Co / COAl 2 O 4 -Al 2 O 3 SO 2 containing glycine.

Catalyst H is prepared in a manner similar to Catalyst G, except that the heat treatment at the end of the preparation at 400 ° C. for 4 hours is carried out under air rather than under nitrogen.

Example 9 (According to the Invention) Catalyst I of Formula Co / COAl2O4-Αΐ2θ3.8Ιθ2 Containing Glycine

Catalyst I is prepared in a manner similar to Catalyst G, except that it is not subjected to thermal treatment under nitrogen at 400 ° C. at the end of the preparation.

Example 10 Catalytic Performance of Catalysts A to I in Fischer-Tropsch Reaction

Catalysts A, B, C, D, E, F, G, H and I, before being tested in Fischer-Tropsch synthesis, are reduced in situ under a flow of pure hydrogen at 400 ° C. for 16 hours. The Fischer-Tropsch synthesis reaction is carried out in a continuous bed-type tubular reactor operating continuously.

Each of the catalysts is in the form of a powder with a diameter of between 40 and 150 microns.

The test conditions are as follows:

• Temperature = 216 "C • Total pressure = 2MPa

Hourly volume velocity (WH) = 4100 NL / h Vkgcatalyst • Molar ratio H2 / CO = 2/1

The results, expressed in terms of activity (conversion of CO in%) and selectivity (percentage by mass of C6 hydrocarbons on all the products formed), are shown in Table 1.

Table 1: Catalytic performances of each catalyst

The results in Table 1 demonstrate that the catalysts according to the invention are more active and / or more selective than the catalysts known from the prior art.

Claims (15)

1) Catalyst containing an active phase of cobalt, deposited on a support comprising alumina, silica or silica-alumina, said support containing a mixed oxide phase containing cobalt and / or nickel, said catalyst being prepared by a process comprising at least: a) a step of contacting a support comprising alumina, silica or sjlice-alumina with at least one solution containing at least one cobalt precursor and or nickel, and then dried and calcined at a temperature between 700 and 1200 ° C, so as to obtain a mixed oxide phase containing cobalt and / or nickel in the support, then b) a step contacting said support containing said mixed oxide phase with at least one solution containing at least one cobalt precursor, c) a step of contacting said support containing said mixed oxide phase with at least one amino acid compound , the stages b) and c) can be performed separately, in any order, or simultaneously, d) and then performs a drying step at a temperature below 200 ° C. 2) Catalyst according to claim 1, wherein the content of mixed oxide phase in the support is between 0.1 and 50% by weight relative to the weight of the support. 3) Catalyst according to one of claims 1 or 2, wherein the mixed oxide phase comprises an akenate of formula COAl 2 O 4 or NiAl 2 O 4 in the case of a support based on alumina or silica-alumina. 4) Catalyst according to one of claims 1 or 2, wherein the mixed oxide phase comprises a silicate of formula Co2Si04 or Ni2Si04 in the case of a support based on silica or silica-alumina. 5) Catalyst according to one of claims 1 to 4, wherein the silica content of said support is between 0.5% by weight to 30% by weight relative to the weight of the support before the formation of the mixed oxide phase when the support is a silica-alumina. 6) Catalyst according to one of claims 1 to 5, wherein the amino acid compound introduced in step c) is an α-amino acid. 7. Catalyst according to claim 6, wherein the amino acid compound is selected from glycine, proline or lysine. 8) Catalyst according to one of claims 1 to 7, wherein the molar ratio of amino acid compound introduced in step c) relative to the cobalt element introduced in step b) is between 0, 01 and 2.0 mol / mol. 9) Catalyst according to one of claims 1 to 8, wherein the content of cobalt element introduced in step b) as active phase is between 2 and 40% by weight expressed as cobalt metal element relative to the weight total catalyst. 10) Catalyst according to one of claims 1 to 9, wherein the catalyst further comprises a member selected from groups VIIIB, IA, IB, IIA, IIB, IIIA, IIIBetVA. 11) The catalyst according to one of claims 1 to 10, wherein the catalyst further contains an organic compound other than the amino acid compound, said organic compound containing oxygen and / or nitrogen. 12) Catalyst according to claim 11, wherein the organic compound is chosen from a compound comprising one or more chemical functional groups chosen from a carboxylic function, alcohol, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide. 13) Catalyst according to one of claims 1 to 12, wherein after the drying step d), a calcination step e) is carried out at a temperature between 200 and 550 ° C, under an inert atmosphere or under an atmosphere containing oxygen. 14) Catalyst according to one of claims 1 to 13, wherein the catalyst obtained in the drying step d) or obtained in the calcining step e) is reduced to a temperature of between 200 ° C and 500 ° C . 15) A Fischer-Tropsch hydrocarbon synthesis process in which the catalyst according to any one of claims 1 to 14 is contacted with a feedstock comprising synthesis gas at a total pressure of between 0.1 and 15 MPa, at a temperature between 150 and 350 ° C, and at a volume hourly velocity of between 100 and 20000 volumes of synthesis gas per volume of catalyst and per hour with a molar ratio H2 / CO of the synthesis gas between 0.5 and 4.