阅读说明：本技术 使来自汽油加氢脱硫方法的失效并再生的催化剂恢复活性的方法 (Process for reactivating spent and regenerated catalyst from gasoline hydrodesulfurization process ) 是由 E·德韦尔 E·吉拉尔 P·勒弗莱夫 于 2019-12-10 设计创作，主要内容包括：本发明涉及使由含硫烯烃汽油馏分的加氢脱硫方法产生的至少部分失效的催化剂恢复活性的方法,所述至少部分失效的催化剂产生自新鲜催化剂,所述新鲜催化剂包含第VIIl族金属,第VIB族金属,氧化物载体和任选的磷,所述方法包括以下步骤：a)使至少部分失效的催化剂在含氧气流中在350℃至550℃的温度下再生,b)使再生的催化剂与至少一种包含含第VIB族金属的化合物的浸渍溶液接触,添加的第VIB族金属与在再生的催化剂中已经存在的第VIB族金属的摩尔比为0.15-2.5 mol/mol,c)在低于200℃的温度下进行干燥步骤以获得恢复活性的催化剂,涉及所述恢复活性的催化剂在这样的加氢脱硫方法中的用途。(The present invention relates to a process for reactivating an at least partially spent catalyst resulting from a process for the hydrodesulphurization of a sulphur-containing olefinic gasoline fraction, said at least partially spent catalyst being derived from a fresh catalyst comprising a group VIIl metal, a group VIB metal, an oxidic support and optionally phosphorus, said process comprising the steps of: a) regenerating an at least partially spent catalyst in an oxygen-containing gas stream at a temperature of 350 ℃ to 550 ℃, b) contacting the regenerated catalyst with at least one impregnation solution comprising a group VIB metal-containing compound, the molar ratio of the added group VIB metal to the group VIB metal already present in the regenerated catalyst being from 0.15 to 2.5mol/mol, c) performing a drying step at a temperature below 200 ℃ to obtain a catalyst with restored activity, to the use of said catalyst with restored activity in such a hydrodesulphurization process.)

1. A process for reactivating an at least partially spent catalyst produced by a process for the hydrodesulfurization of a sulfur-containing olefinic gasoline fraction, said at least partially spent catalyst being produced from a fresh catalyst comprising at least one group vil metal, at least one group VIB metal, an oxidic support and optionally phosphorus, said process comprising the steps of:

a) regenerating the at least partially spent catalyst in an oxygen-containing gas stream at a temperature of from 350 ℃ to 550 ℃ to obtain a regenerated catalyst,

b) contacting the regenerated catalyst with at least one impregnation solution comprising at least one group VIB metal-containing compound, the molar ratio of the added group VIB metal to the group VIB metal already present in the regenerated catalyst being in the range of from 0.15 to 2.5mol/mol,

c) the drying step is carried out at a temperature below 200 ℃ to obtain a catalyst with restored activity.

2. The process according to the preceding claim, wherein, in step b), the impregnation solution further comprises a compound containing a group VIII metal; the molar ratio of the added group VIII metal to the group VIII metal already present in the regenerated catalyst is from 0.1 to 2.5 mol/mol.

3. The method according to any one of the preceding claims, wherein in step b) the impregnation solution further comprises phosphorus; the molar ratio of added phosphorus to group VIB metal already present in the regenerated catalyst is from 0.1 to 2.5 mol/mol.

4. The process according to any one of the preceding claims, wherein, in step b), the impregnation solution further comprises an organic compound comprising oxygen and/or nitrogen and/or sulphur; the molar ratio of the added organic compound to the group VIB metal already present in the regenerated catalyst is from 0.01 to 5 mol/mol.

5. The process according to the preceding claim, wherein the organic compound comprising oxygen and/or nitrogen and/or sulphur is selected from compounds comprising one or more chemical functional groups selected from carboxylic acid, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea or amide functional groups or compounds comprising a furan ring or a sugar.

6. Process according to the preceding claim, in which the organic compound comprising oxygen and/or nitrogen and/or sulphur is chosen from gamma valerolactone, 2-acetylbutyrolactone, triethylene glycol, diethylene glycol, ethylene glycol, ethylenediaminetetraacetic acid, maleic acid, malonic acid, citric acid, gluconic acid, di (C) succinate₁-C₄Alkyl) esters, glucose, fructose, sucrose, sorbitol, xylitol, gamma-ketovaleric acid, dimethylformamide, 1-methyl-2-pyrrolidone, propylene carbonate, 2-methoxyethyl 3-oxobutyrate, N, N-dihydroxyethylglycine, tris (hydroxymethyl) methylglycine, 2-furfural, 5-hydroxymethylfurfural, 2-acetylfuran, 5-methylfuran-2-furfural, ascorbic acid, butyl lactate, ethyl 3-hydroxybutyrate, ethyl 3-ethoxypropionate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-hydroxyethyl acrylate, 1-vinyl-2-pyrrolidone, 1, 3-dimethyl-2-imidazolidinone, 1- (2-hydroxyethyl) -2-pyrrolidone, 1- (2-hydroxyethyl) -2, 5-pyrrolidinone, 5-methyl-2 (3H) -furanone, 1-methyl-2-piperidone and 4-aminobutyric acid.

7. The process according to any one of the preceding claims, wherein the regeneration step a) is preceded by a deoiling step comprising contacting the at least partially spent catalyst with a flow of inert gas at a temperature of from 300 ℃ to 400 ℃.

8. The process according to any one of the preceding claims, wherein at the end of drying step c), calcination step d) is carried out at a temperature of from 200 ℃ to 600 ℃.

9. The process according to any one of the preceding claims, wherein the fresh catalyst has a group VIB metal content of from 1% to 20% by weight of said group VIB metal oxide, relative to the total weight of the catalyst, and a group VIII metal content of from 0.1% to 10% by weight of said group VIII metal oxide, relative to the total weight of the catalyst.

10. The process according to any of the preceding claims, wherein the fresh catalyst is in P₂O₅Expressed as a phosphorus content ranging from 0.3% to 10% by weight relative to the total weight of the catalyst, and a phosphorus/(group VIB metal) molar ratio in the catalyst ranging from 0.1 to 0.7.

11. A process according to any one of the preceding claims, wherein the oxide support of the fresh catalyst is selected from alumina, silica-alumina, or titanium or magnesium oxide, used alone or as a mixture with alumina or silica-alumina.

12. The process according to any of the preceding claims, wherein the fresh catalyst is characterized by a specific surface area of 20 to 200 m/g, preferably 30 to 180 m/g.

13. A process for hydrodesulphurization of a gasoline fraction containing sulphur olefins, wherein said gasoline fraction, hydrogen and a catalyst recovering the activity of the process according to any one of claims 1-12 are contacted, said hydrodesulphurization process being carried out at a temperature of from 200 ℃ to 400 ℃ and at a total pressure of from 1 to 3MPa, at an hourly space velocity of from 1 to 10h^-1And the hydrogen/gasoline feed volume ratio was 100-1200Sl/l, the hourly space velocity being defined as the feed volumetric flow rate relative to the catalyst volume.

14. Process according to the preceding claim, in which the reactivated catalyst is subjected to a sulfurization step before or during the hydrodesulphurization process.

15. Process according to any one of claims 13 and 14, carried out in a catalytic bed of a fixed bed type reactor comprising a plurality of catalytic beds; at least one other catalytic bed upstream or downstream of the catalytic bed containing the catalyst with restored activity, in the feed circulation direction, contains at least partially fresh catalyst and/or regenerated catalyst.

16. The process according to any one of claims 13 to 15, carried out in at least two reactors of fixed bed type or ebullating bed type in series; in any order, at least one of the reactors contains a reactivated catalyst and the other reactor contains fresh catalyst or regenerated catalyst, or a mixture of reactivated catalyst and fresh and/or regenerated catalyst, with or without removal of at least a portion of the H from the effluent produced from the first reactor prior to treatment of the effluent in the second reactor₂S。

Technical Field

The present invention relates to a process for reactivating a catalyst used in a process for the hydrodesulphurization of gasoline fractions and to the use of the reactivated catalyst in such a process.

Background

Sulfur is an element naturally present in crude oil and, therefore, if not removed during the refining process, is present in gasoline and diesel. However, sulfur in gasoline can impair the efficiency of the emission reduction system (catalytic converter) and cause air pollution. In order to combat environmental pollution, therefore, all countries are increasingly adopting strict sulfur regulations, such as 10ppm (by weight) of sulfur in gasoline sold in europe, china, the united states and japan. The problem of reducing the sulfur content focuses mainly on the gasoline obtained by cracking, whether catalytic (FCC, fluid catalytic cracking) or non-catalytic (coking, visbreaking, steam cracking), which is the main precursor of sulfur in the gasoline pool.

A solution for reducing the sulfur content, well known to the person skilled in the art, consists in hydrotreating (or hydrodesulphurizing) a hydrocarbon fraction, in particular a catalytically cracked gasoline, in the presence of hydrogen and a heterogeneous catalyst. However, this process has the major drawback of causing a very significant reduction in octane number if the catalyst used is not sufficiently selective. This reduction in octane number is particularly associated with the hydrogenation of the olefins present in this type of gasoline, which is associated with hydrodesulfurization.

Unlike other hydrotreating processes, in particular for feedstocks of the gas oil type, the hydrodesulfurization of gasolines must therefore allow the handling of double adverse conditions: provide deep hydrodesulfurization of gasoline and limit hydrogenation of unsaturated compounds present.

The most widely used approach to solve the above dual problems consists in adopting the following methods: wherein the sequence of unit steps allows to maximize hydrodesulfurization while limiting hydrogenation of olefins. Thus, the latest processes, such as the Prime G + (trademark) process, allow to desulfurize pyrolysis gasolines rich in olefins, while limiting the hydrogenation of the mono-olefins and therefore the loss of octane and the high hydrogen consumption resulting therefrom. Such a process is described, for example, in patent applications EP1077247 and EP 1174485.

Thus, the desired reaction option is obtainedThe nature (ratio of hydrodesulfurization to olefin hydrogenation) may be due in part to the choice of process, but in all cases, the use of an inherently selective catalytic system is often a critical factor. Typically, the catalysts used for such applications are sulfide type catalysts containing group VIB elements (Cr, Mo, W) and group VIII elements (Fe, Ru, Os, Co, Rh, Ir, Pd, Ni, Pt). Thus, in patent US5985136, it is claimed that the surface concentration is 0.5 × 10^-4To 3X 10^-4g MoO₃/m²The catalyst of (a) allows to achieve a high hydrodesulphurisation selectivity (93% Hydrodesulphurisation (HDS) versus 33% olefin Hydrogenation (HOO)). Furthermore, according to patents US4140626 and US4774220, it may be advantageous to add dopants (alkali metals, alkaline earth metals) to the conventional sulphide phase (CoMoS) to limit hydrogenation of olefins. Also known in the prior art are documents US8637423 and EP1892039, which describe selective hydrodesulfurization catalysts.

During its use in the hydrotreatment of petroleum fractions, the hydrotreating catalyst undergoes its reduction in activity due to the deposition of coke and/or compounds based on sulphur or containing other hetero elements. Therefore, after a certain time, it needs to be replaced. In particular, increases in sulfur specifications for fuels result in increased frequency of catalyst replacement, which results in increased costs associated with the catalyst and an increase in the amount of spent catalyst.

To overcome these drawbacks, the regeneration (mild calcination) of the catalysts used for the hydrodesulphurization of middle distillates (gas oils) or waste residues is an economically and ecologically advantageous process, since it allows to reuse these catalysts in industrial plants, instead of landfilling or recovering them (recovering metals). However, the regenerated catalyst is generally less active than the starting solid.

In order to overcome the deficiency of the hydrodesulphurisation activity of the regenerated catalyst, an additional "rejuvenation" treatment may be carried out. The method of restoring activity consists in re-impregnating the regenerated catalyst with a solution containing a metal precursor in the presence of an organic or inorganic additive. These "rejuvenation" methods are well known to those skilled in the art in the field of middle distillates. Many patents, such as, for example, US7906447, US8722558, US7956000, US7820579 or also CN102463127, thus provide different methods for carrying out the activity recovery of the catalyst for the hydrotreatment of middle distillates. Document US2017/036202 describes an increase in activity in a diesel hydrotreating process when a group VIB metal and phosphorus are added to the regenerated catalyst. Catalysts for the hydrodesulfurization of middle distillates, which have a high metal content compared to catalysts for the selective hydrodesulfurization of gasoline, undergo significant sintering during use and regeneration. Therefore, the reactivation treatment is focused on the dissolution and redistribution of the metallic phase in order to recover a dispersion close to the fresh catalyst and thus obtain an activity close to the fresh catalyst. Current methods for restoring activity of hydrotreating catalysts have been developed only for restoring hydrodesulfurization activity of catalysts used for hydrodesulfurization of middle distillates.

Catalysts for selective hydrodesulfurization of cracked gasolines have different problems of recovery activity than catalysts for hydrotreating gas oils, in particular due to the need to maintain the selectivity of the catalyst in terms of hydrodesulfurization and hydrogenation reactions of olefins. This is because it is generally more desirable to increase the selectivity than to increase or maintain the activity in the gasoline field. Therefore, there is a great benefit to develop a specific method of restoring activity to catalysts for the selective hydrodesulfurization of gasoline.

This method of restoring activity is described in patent CN105642312 for spent catalysts used for the selective hydrodesulfurization of FCC gasoline. In addition to the organic reagent, this complex process uses one or more metal additives comprising at least one of the elements selected from the group consisting of Na, K, Mg, Ca, Cu and Zn; and heat treated using an atmosphere having a controlled oxygen content.

Therefore, today, there is a strong interest in the manufacturers and regeneration enterprises of catalysts and refineries for the recovery of the activity of hydrodesulphurization catalysts, in particular catalysts for the hydrodesulphurization of gasoline cuts, which have a maintained or even improved quality of catalytic performance, in particular in terms of hydrodesulphurization catalytic activity and/or selectivity, and which therefore, once used, allow the production of gasolines with a low sulphur content without seriously reducing the octane number.

The present invention therefore relates to a "rejuvenation" process suitable for selective hydrodesulfurization catalysts, with the aim of fully rejuvenating the hydrodesulfurization activity of the catalyst and maintaining the selectivity of the fresh catalyst, indeed even improving them.

Disclosure of Invention

The present invention relates to a process for reactivating an at least partially spent catalyst produced by a process for the hydrodesulphurization of a gasoline fraction containing sulphur olefins, said at least partially spent catalyst being produced from a fresh catalyst comprising at least one group VIIl metal, at least one group VIB metal, an oxidic support and optionally phosphorus, said process comprising the steps of:

a) regenerating the at least partially spent catalyst in an oxygen-containing gas stream at a temperature of from 350 ℃ to 550 ℃ to obtain a regenerated catalyst,

b) contacting the regenerated catalyst with at least one impregnation solution comprising at least one group VIB metal-containing compound, the molar ratio of the added group VIB metal to the group VIB metal already present in the regenerated catalyst being in the range of from 0.15 to 2.5mol/mol,

c) the drying step is carried out at a temperature below 200 ℃ to obtain a catalyst with restored activity.

This is because it has been observed that the method of restoring activity according to the invention allows to obtain a catalyst of restored activity showing an improved catalytic activity compared to the use of the same fresh catalyst and surprisingly causes an improvement of the selectivity in processes for the selective hydrodesulphurization of gasoline. Without being bound by any theory, it appears that the change in the active phase caused by restoring the activity of the regenerated catalyst leads to a better selectivity of the hydrodesulfurization reaction towards the active sites and makes it possible to compensate for the reduction in the number of these sites and thus to maintain the activity of the catalyst.

According to an alternative form, in step b), the impregnation solution also comprises a compound containing a metal of group VIII; the molar ratio of the added group VIII metal to the group VIII metal already present in the regenerated catalyst is from 0.1 to 2.5 mol/mol.

According to an alternative form, in step b), the impregnation solution also comprises phosphorus; the molar ratio of added phosphorus to group VIB metal already present in the regenerated catalyst is from 0.1 to 2.5 mol/mol.

According to an alternative form, in step b), the impregnation solution also comprises an organic compound comprising oxygen and/or nitrogen and/or sulphur; the molar ratio of the added organic compound to the group VIB metal already present in the regenerated catalyst is from 0.01 to 5 mol/mol.

According to an alternative form, the organic compound containing oxygen and/or nitrogen and/or sulphur is chosen from compounds comprising one or more chemical functions chosen from carboxylic acid functions, alcohols, thiols, thioethers, sulfones, sulfoxides, ethers, aldehydes, ketones, esters, carbonates, amines, nitriles, imides, oximes, ureas or amide functions, or compounds or sugars comprising a furan ring.

According to an alternative form, the organic compound comprising oxygen and/or nitrogen and/or sulphur is selected from gamma valerolactone, 2-acetylbutyrolactone, triethylene glycol, diethylene glycol, ethylene glycol, ethylenediamine tetraacetic acid, maleic acid, malonic acid, citric acid, gluconic acid, di (C1-C4 alkyl) succinate, glucose, fructose, sucrose, sorbitol, xylitol, gamma-ketovaleric acid, dimethylformamide, 1-methyl-2-pyrrolidone, propylene carbonate, 2-methoxyethyl 3-oxobutyrate, N, N-dihydroxyethylglycine, tris (hydroxymethyl) methylglycine, 2-furfural, 5-hydroxymethylfurfural, 2-acetylfuran, 5-methyl-2-furfural, ascorbic acid, butyl lactate, ethyl 3-hydroxybutyrate, ethyl 3-ethoxypropionate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-hydroxyethyl acrylate, 1-vinyl-2-pyrrolidone, 1, 3-dimethyl-2-imidazolidinone, 1- (2-hydroxyethyl) -2-pyrrolidone, 1- (2-hydroxyethyl) -2, 5-pyrrolidinedione, 5-methyl-2 (3H) -furanone, 1-methyl-2-piperidone and 4-aminobutyric acid.

According to an alternative form, the regeneration step a) is preceded by a deoiling step which comprises contacting the at least partially spent catalyst with a flow of inert gas at a temperature of between 300 ℃ and 400 ℃.

According to an alternative form, at the end of the drying step c), the calcination step d) is carried out at a temperature of between 200 ℃ and 600 ℃.

According to an alternative form, the fresh catalyst has a content of group VIB metal of between 1% and 20% by weight of oxide of said group VIB metal, relative to the total weight of the catalyst.

According to an alternative form, the fresh catalyst has a content of group VIII metal of between 0.1% and 10% by weight of oxide of said group VIII metal, relative to the total weight of the catalyst.

According to an alternative form, the fresh catalyst is in the form of P₂O₅Expressed as a phosphorus content ranging from 0.3% to 10% by weight relative to the total weight of the catalyst, and a phosphorus/(group VIB metal) molar ratio in the catalyst ranging from 0.1 to 0.7.

According to one alternative, the oxide support of the fresh catalyst is chosen from alumina, silica-alumina, or titanium or magnesium oxide, used alone or as a mixture with alumina or silica-alumina.

According to an alternative form, the fresh catalyst is characterized by a particle size of 20 to 200m²Per g, preferably from 30 to 180m²Specific surface area in g.

The invention also relates to a process for the hydrodesulphurization of a gasoline fraction containing sulphur olefins, in which the gasoline fraction, hydrogen and a catalyst whose activity is restored according to the process of the invention are brought into contact, the hydrodesulphurization process being carried out at a temperature of from 200 ℃ to 400 ℃ and at a total pressure of from 1 to 3MPa and at an hourly space velocity (defined as the feed volume flow rate with respect to the volume of the catalyst) of from 1 to 10h^-1And the volume ratio of hydrogen/gasoline feed was 100-1200 Sl/l.

According to one alternative, the reactivated catalyst is subjected to a sulfurization step before or during the hydrodesulphurization process.

According to an alternative form, the hydrodesulfurization process is carried out in a catalytic bed of a reactor of the fixed-bed type comprising a plurality of catalytic beds; at least one other catalytic bed upstream or downstream of the catalytic bed containing the catalyst with restored activity, in the feed circulation direction, contains at least partially fresh catalyst and/or regenerated catalyst.

According to an alternative form, the hydrodesulfurization process is carried out in at least two reactors of the fixed bed type or of the ebullating bed type, connected in series; at least one of the reactors contains a reactivated catalyst and the other reactor contains fresh catalyst or regenerated catalyst, or a mixture of reactivated catalyst and fresh and/or regenerated catalyst, in any order, with or without removal of at least a portion of the H from the effluent produced from the first reactor prior to treatment of the effluent in the second reactor₂S。

Subsequently, the family of chemical elements is given according to the CAS classification (CRC Handbook of Chemistry and Physics, CRC Press, ed. R.Lide, 81 th edition, 2000-. For example, group VIII according to the CAS classification corresponds to the metals in columns 8, 9 and 10 according to the new IUPAC classification.

Description of the invention

The activity-restored catalyst obtained by the process according to the invention is produced from an at least partially spent catalyst, which is itself produced from a fresh catalyst that has been used for a certain time in a process for the hydrodesulphurization of sulphur-containing olefinic gasoline cuts under the conditions described below and which exhibits a significantly lower activity than the fresh catalyst, requiring its replacement.

Fresh catalysts for use in processes for hydrodesulfurizing gasoline fractions containing sulfur olefins are known to those skilled in the art. It comprises at least one group VIIl metal, at least one group VIB metal, an oxidic support and optionally phosphorus and/or an organic compound, as described below. According to another alternative form, the fresh catalyst does not comprise phosphorus.

The preparation of fresh catalyst is known and generally comprises: the step of impregnating the metals of groups VIII and VIB, and optionally phosphorus and/or organic compounds, on the oxide support, followed by a drying operation, and then an optional calcination, allows to obtain the active phase in its oxide form. Before the fresh catalyst is used in a process for the hydrodesulphurization of sulphur-containing olefinic gasoline cuts, it is generally sulphided to form an active mass as described below.

According to an alternative form of the invention, the fresh catalyst has not been calcined during its preparation, that is to say the impregnated catalyst precursor has not been subjected to a heat treatment step at a temperature higher than 200 ℃, under an inert atmosphere or under an oxygen-containing atmosphere, in the presence or absence of water.

According to another preferred alternative form of the invention, the fresh catalyst is subjected to a calcination step during its preparation, that is to say the impregnated catalyst precursor has been subjected to a heat treatment step at a temperature of from 250 ℃ to 1000 ℃, preferably from 200 ℃ to 750 ℃, during a period of time generally from 15 minutes to 10 hours, in an inert atmosphere or in an oxygen-containing atmosphere, in the presence or absence of water.

The group VIB metal present in the active phase of the fresh catalyst is preferably selected from molybdenum and tungsten. The group VIII metal present in the active phase of the fresh catalyst is preferably selected from cobalt, nickel and mixtures of these two elements. The active phase of the fresh catalyst is preferably selected from the elemental combinations nickel-molybdenum, cobalt-molybdenum and nickel-cobalt-molybdenum, and very preferably the active phase consists of cobalt and molybdenum.

The content of group VIII metal is from 0.1 to 10% by weight of the oxide of group VIII metal, preferably from 0.6 to 8% by weight, preferably from 2 to 7% by weight, very preferably from 2 to 6% by weight and more preferably from 2.5 to 6% by weight, relative to the total weight of the fresh catalyst.

The content of group VIB metal is from 1 to 20% by weight of group VIB metal oxide, preferably from 2 to 18% by weight, very preferably from 3 to 16% by weight, relative to the total weight of the fresh catalyst.

The fresh catalyst generally has a group VIII to group VIB metal molar ratio of from 0.1 to 0.8, preferably from 0.2 to 0.6.

In addition, the fresh catalyst has a density of group VIB metal (expressed as the number of atoms of said metal per unit area of the catalyst) of from 0.5 to 30, preferably from 2 to 25, more preferably from 3 to 15, group VIB metal atoms/nm²A catalyst. Density of group VIB metal, expressed as number of atoms of group VIB metal per unit area of catalyst (number of atoms of group VIB metal/nm)²Catalyst), for example, according to the following relationship:

wherein:

x = weight% of group VIB metal;

• N_A= avocado constant, equal to 6.022 × 10²³；

S = specific surface area of catalyst (m/g), measured according to standard ASTM D3663;

• M_Mgroup VIB metal (e.g., 95.94g/mol for molybdenum).

For example, if the catalyst comprises 20% by weight of molybdenum oxide MoO₃(i.e., 13.33 wt% Mo) and having a specific surface area of 100 m/g, then density d (Mo) is equal to:

。

catalysts used for the hydrodesulfurization of gasoline are generally different from the more dense group VIB metal catalysts used for the hydrodesulfurization of gas oil type middle distillates. This is because, even though the catalysts used for the hydrodesulphurization of gasoline generally have a lower content of group VIB metals than the catalysts used for middle distillates, the specific surface area of the gasoline catalysts is much higher (generally greater than 200 m) than that of the catalysts used for middle distillates²/g), which results in a higher group VIB metal density.

Optionally, relative to freshThe fresh catalyst may additionally have a phosphorus content of generally from 0.3 to 10% by weight of P, based on the total weight of the catalyst₂O₅Preferably from 0.5 to 5% by weight, very preferably from 1 to 3% by weight, of P₂O₅. For example, the phosphorus present in the fresh catalyst is combined in the form of a heteropolyanion with the group VIB metal and optionally also with the group VIII metal.

Furthermore, when phosphorus is present, the molar ratio phosphorus/(group VIB metal) is generally from 0.1 to 0.7, preferably from 0.2 to 0.6.

Preferably, the fresh catalyst is characterized by the specific surface area of 5 to 400 m/g, preferably 10 to 250 m/g, preferably 20 to 200 m/g, very preferably 30 to 180 m/g. In the present invention, the specific surface area is determined by the BET method according to ASTM D3663, as described in Rouquerol F., Rouquerol J. and Singh KAdsorption by Powders & Porous Solids: Principle, Methodology and ApplicationsAcademic Press, 1999, e.g., by Micromeritics^TMBrand Autopore III^TMThe assay was performed in a model apparatus.

The pore volume of the fresh catalyst is generally 0.4cm³G to 1.3cm³In g, preferably 0.6cm³G to 1.1cm³(ii) in terms of/g. As described in that same work, the total pore volume is measured by mercury porosimetry according to the ASTM D4284 standard, with a wetting angle of 140 °.

The Tapped Bulk Density (TBD) of the fresh catalyst is generally in the range from 0.4 to 0.7g/ml, preferably from 0.45 to 0.69 g/ml. The measurement of the TBD consists in introducing the catalyst into a graduated cylinder, the volume of which has been predetermined, and then knocking it by vibration until a constant volume is obtained. The bulk density of the knocked product is calculated by comparing the mass introduced with the volume occupied by the knocked product.

The fresh catalyst may be in the form of a cylindrical or multilobal (trilobal, quadralobal, etc.) extrudate or a sphere having a small diameter.

The oxidic support of the fresh catalyst is typically a porous solid selected from: alumina, silica-alumina and titanium and magnesium oxides, used alone or as a mixture with alumina or silica-alumina. It is preferably selected from the group consisting of silica, transition alumina and silica-alumina species; very preferably, the oxide support consists essentially of at least one transition alumina, that is to say it comprises at least 51% by weight, preferably at least 60% by weight, very preferably at least 80% by weight, indeed even at least 90% by weight of transition alumina. It preferably consists only of transition alumina. Preferably, the oxidic support of the fresh catalyst is a "high temperature" transition alumina, that is to say, it comprises theta-, delta-, kappa-or alpha-phase alumina, alone or in a mixture, and gamma-, chi-or eta-phase alumina in an amount of less than 20%.

The fresh catalyst may additionally comprise at least one organic compound containing oxygen and/or nitrogen and/or sulphur before the sulphidation. Such additives are described later.

In the hydrotreating process, coke and sulfur, as well as other contaminants produced from the feed, such as silicon, arsenic or chlorine, are formed and/or deposited on the catalyst and convert the fresh catalyst into an at least partially spent catalyst.

Thus, an at least partially spent catalyst consists of the oxidic support from the fresh catalyst and an active phase formed from at least one group VIB metal and at least one group VIII metal and optionally phosphorus, as well as carbon, sulphur and optionally other contaminants (such as silicon, arsenic and chlorine) resulting from the feed.

In fresh, at least partially spent, regenerated or reactivated catalyst, the contents of group VIB metals, group VIII metals and phosphorus were expressed as oxides after correcting for the loss on ignition of the catalyst sample (550 ℃ in a muffle furnace for 2 hours). Loss on ignition results from the loss of moisture, carbon, sulfur and/or other contaminants. It was determined according to ASTM D7348.

In the at least partially spent catalyst, the group VIB metal, the group VIII metal and optionally the phosphorus are present in substantially the same amount as in the fresh catalyst from which it was produced.

An at least partially spent catalyst is understood to mean a catalyst which is discharged from a process for the hydrodesulphurization of gasoline fractions containing sulphur olefins carried out under conditions and which has not undergone a thermal treatment carried out at a temperature greater than 200 ℃ under a gas comprising air or oxygen. It may have undergone de-oiling.

It should be noted that the term "coke" or "carbon" in the present patent application denotes a hydrocarbon-based substance which is deposited on the surface of the catalyst during use of the catalyst, which is highly cyclized and condensed and has a similar appearance to graphite.

The at least partially spent catalyst comprises in particular carbon, in a content generally greater than or equal to 2% by weight, preferably ranging from 2% to 10% by weight and more preferably ranging from 2.2% to 6% by weight, with respect to the total weight of the at least partially spent catalyst. The carbon content was measured by elemental analysis according to ASTM D5373.

The at least partially spent catalyst comprises sulfur in an amount of 1 to 8 wt.%, preferably 1 to 6.0 wt.%, and particularly preferably 2 to 5 wt.%, relative to the total weight of the at least partially spent catalyst. The residual sulfur content in the at least partially spent catalyst was measured by elemental analysis according to ASTM D5373.

Optionally, the at least partially spent catalyst may additionally exhibit a low content of contaminants, such as silicon, arsenic or chlorine, resulting from the feed treated by the fresh catalyst from which the at least partially spent catalyst was produced.

Preferably, the content of silicon (apart from silicon possibly present on fresh catalyst) is less than 2% by weight, and very preferably less than 1% by weight, relative to the total weight of the at least partially spent catalyst.

The arsenic content is preferably less than 2000ppm by weight, and very preferably less than 500ppm by weight, relative to the total weight of the at least partially spent catalyst.

The chlorine content is preferably less than 2000ppm by weight, and very preferably less than 500ppm by weight, relative to the total weight of the at least partially spent catalyst.

Regeneration (step a)

The process according to the invention for reactivating an at least partially spent catalyst comprises a step of removing coke and sulphur (regeneration step). This is because, according to step a) of the process of the present invention, the at least partially spent catalyst is regenerated in an oxygen-containing gas stream at a temperature of from 350 ℃ to 550 ℃ to obtain a regenerated catalyst.

Even if this is possible, the regeneration is preferably not carried out by keeping the added catalyst in the hydroprocessing reactor (in situ regeneration). Preferably, the at least partially spent catalyst is thus withdrawn from the reactor and sent to a regeneration unit for regeneration in said unit (ex situ regeneration).

Preferably there is a de-oiling step prior to the regeneration step a). The de-oiling step typically comprises contacting the at least partially spent catalyst with a stream of inert gas (i.e. substantially free of oxygen), for example in a nitrogen atmosphere or the like, at a temperature of from 300 ℃ to 400 ℃, preferably from 300 ℃ to 350 ℃. The inert gas flow rate is from 5 to 150S 1.1 in terms of flow rate per unit volume of catalyst^-1.h^-1For 3 to 7 hours.

In an alternative form, the deoiling step may be carried out by light hydrocarbons, by steam treatment or any other similar method.

The de-oiling step allows the removal of soluble hydrocarbons and thus releases the porosity of the at least partially spent catalyst required for restoring activity.

The regeneration step a) is generally carried out in an oxygen-containing gas stream, generally air. The water content is generally from 0 to 50% by weight. The gas flow rate (in terms of flow rate per unit volume of at least partially spent catalyst) is preferably from 20 to 2000 sl.1^-1.h^-1More preferably 30 to 1000 Sl.1^-1.h^-1And particularly preferably from 40 to 500 sl.1^-1.h^-1. The duration of the regeneration is preferably 2 hours or more, more preferably 2.5 hours or more, and particularly preferably 3 hours or more. The regeneration of the at least partially spent catalyst is generally carried out at a temperature of from 350 ℃ to 550 ℃, preferably from 360 ℃ to 500 ℃.

Thus, the regenerated catalyst consists of the oxidic support and the active phase formed by at least one metal selected from group VIB and at least one group VIII and optionally phosphorus (resulting from the fresh catalyst) as well as residual carbon, residual sulphur and optionally other contaminants (resulting from the feed), such as silicon, arsenic and chlorine.

The content of group VIB metals, group VIII metals and optionally phosphorus in the regenerated catalyst is essentially the same as the content of the at least partially spent catalyst and as the content of the fresh catalyst from which the at least partially spent catalyst is produced.

The regenerated catalyst obtained in the regeneration step comprises residual carbon, preferably in a content of less than 2% by weight, preferably from 0.1% by weight to 1.9% by weight, preferably from 0.1% by weight to 1.5% by weight, and particularly preferably from 0.1% by weight to 1.0% by weight, relative to the total weight of the regenerated catalyst. The regenerated catalyst may also contain no residual carbon.

It should be noted that the term "residual carbon" in this patent application refers to the carbon (coke) that remains in the regenerated catalyst after regenerating the at least partially spent catalyst. The residual carbon content in the regenerated catalyst was measured by elemental analysis according to ASTM D5373.

The regenerated catalyst obtained in the regeneration step comprises residual sulphur (before optional sulphiding) in an amount of less than 5% by weight, preferably from 0.1% to 4.9% by weight, preferably from 0.1% to 2.0% by weight and particularly preferably from 0.2% to 0.8% by weight, relative to the total weight of the regenerated catalyst. The regenerated catalyst may also contain no residual sulfur.

The residual sulfur content in the regenerated catalyst was measured by elemental analysis according to ASTM D5373.

Restoration of Activity (step b)

After the regeneration step a), the method for restoring activity according to the invention comprises a step b) of restoring activity, according to which the regenerated catalyst is brought into contact with at least one impregnation solution containing at least one compound comprising a group VIB metal, the molar ratio of the group VIB metal added to the group VIB metal already present in the regenerated catalyst being from 0.15 to 2.5mol/mol, preferably from 0.2 to 2.0mol/mol, and more preferably from 0.3 to 1.0 mol/mol.

This is because, during the use of the catalyst in a process for the hydrodesulphurization of gasoline, the pores of the support become blocked with the passage of time and the active phase containing the metal becomes increasingly difficult to access. A reduction in catalytic activity is therefore observed, not being completely restored even after regeneration. In order to overcome the deficiency of hydrodesulphurisation activity, the catalyst may be re-impregnated with a solution comprising a group VIB metal containing compound and optionally also a group VIII metal containing compound and/or phosphorus, in order to limit the activity drop and surprisingly increase the selectivity.

According to a first alternative, the reactivation step b) can also comprise contacting the regenerated catalyst with an impregnation solution containing, in addition to the compound of the group VIB metal, a compound of the group VIII metal.

In this case, the molar ratio of the group VIII metal added to the group VIII metal already present in the regenerated catalyst is from 0.1 to 2.5mol/mol, preferably from 0.1 to 2.0mol/mol and more preferably from 0.1 to 1.0 mol/mol.

According to a preferred alternative of this first alternative, the impregnation solution comprises, in addition to the solvent or solvents, only one or more compounds containing a group VIB metal and one or more compounds containing a group VIII metal.

The group VIB metal introduced is preferably selected from molybdenum and tungsten. The group VIII metal introduced is preferably selected from cobalt, nickel and mixtures of these two elements. Preferably, the elements nickel-molybdenum, cobalt-molybdenum and nickel-cobalt-molybdenum are selected in combination, and very preferably, the cobalt-molybdenum combination is selected.

For example, among the sources of molybdenum, oxides and hydroxides, molybdic acid and their salts, in particular ammonium salts, such as ammonium molybdate, ammonium heptamolybdate, phosphomolybdic acid (H)₃PMo₁₂O₄₀) And their salts, and optionally silicomolybdic acid (H)₄SiMo₁₂O₄₀) And salts thereof. The molybdenum source may also beSuch as any heteropoly compound of the Keggin, Keggin-deficient, substituted Keggin, Dawson, Anderson or Strandberg types. Molybdenum trioxide and Keggin, absent Keggin (lacunary Keggin), substituted Keggin and Strandberg-type heteropoly compounds are preferably used.

Tungsten precursors that can be used are also well known to those skilled in the art. For example, in tungsten sources, oxides and hydroxides, tungstic acid and salts thereof, in particular ammonium salts, such as ammonium tungstate, ammonium metatungstate, phosphotungstic acid and salts thereof, and optionally silicotungstic acid (H)₄SiW₁₂O₄₀) And salts thereof. The tungsten source may also be any heteropoly compound such as Keggin, absent Keggin, substituted Keggin or Dawson type. Preferably, oxides and ammonium salts are used, such as ammonium metatungstate or Keggin, and hetero-polyanions of the Keggin-deficient or substituted Keggin type.

Cobalt precursors which may be used are advantageously selected from, for example, oxides, hydroxides, hydroxycarbonates, carbonates and nitrates. Cobalt hydroxide and cobalt carbonate are preferably used.

The nickel precursors which can be used are advantageously chosen, for example, from oxides, hydroxides, hydroxycarbonates, carbonates and nitrates. Nickel hydroxide and nickel hydroxycarbonate are preferably used.

According to a second alternative, the reactivation step b) may also comprise contacting the regenerated catalyst with an impregnation solution also containing phosphorus (in addition to the compound comprising a group VIB metal and optionally the compound comprising a group VIII metal).

In this case, the molar ratio of the added phosphorus to the group VIB metal already present in the regenerated catalyst is from 0.1 to 2.5mol/mol, preferably from 0.1 to 2.0mol/mol, and more preferably from 0.1 to 1.0 mol/mol.

According to a preferred alternative of this second alternative, the impregnation solution, apart from the solvent or solvents, comprises only one or more compounds containing a group VIB metal and one or more compounds containing a group VIII metal and phosphorus, preferably in the form of phosphoric acid.

The preferred phosphorus precursor is orthophosphoric acid H₃PO₄But salts and esters thereofAmmonium phosphates, for example, are also suitable. Phosphorus can also be introduced simultaneously with the VIB group elements in the form of Keggin, vacancy Keggin, substituted Keggin or Strandberg type heteropolyanions.

Step b) of contacting the regenerated catalyst with an impregnation solution comprising a group VIB metal containing compound and optionally a group VIII metal containing compound and/or phosphorus may be performed by slurry impregnation, or by excess impregnation, or by dry impregnation, or by any other means known to the person skilled in the art.

Equilibrium (or excess) impregnation consists in immersing the support or catalyst in a volume of solution that is greater (usually significantly greater) than the pore volume of the support or catalyst, while keeping the system stirred, to improve the exchange between the solution and the support or catalyst. After diffusion of the different entities into the pores of the support or catalyst, an equilibrium is finally reached. The amount of deposited elements is controlled by pre-measuring an adsorption isotherm that relates the concentration of the element to be deposited contained in the solution to the amount of the element deposited on the solid at equilibrium of the solution.

Dry impregnation consists, for its part, in introducing a volume of impregnation solution equal to the pore volume of the support or catalyst. Dry impregnation may deposit all the metals and additives contained in the impregnation solution on a given support or catalyst.

Step b) can advantageously be carried out using the impregnation solution by one or more impregnation with excess solution or preferably by one or more dry impregnation and very preferably by a single dry impregnation of the regenerated catalyst.

According to a third alternative, the step b) of restoring the activity may also comprise contacting the regenerated catalyst with an impregnation solution comprising organic compounds containing oxygen and/or nitrogen and/or sulphur, in addition to the compound containing the group VIB metal and optionally the compound containing the group VIII metal and/or phosphorus. The function of the additive or organic compound is to increase the catalytic activity compared to a catalyst without the additive. The organic compound is preferably impregnated on the catalyst after being dissolved in an aqueous solution or a non-aqueous solution.

In this case, the molar ratio of the organic compound added to the group VIB metal already present in the regenerated catalyst is from 0.01 to 5mol/mol, preferably from 0.05 to 3mol/mol, preferably from 0.05 to 2mol/mol and very preferably from 0.1 to 1.5 mol/mol.

When multiple organic compounds are present, different molar ratios apply to each organic compound present.

According to a preferred alternative of this third alternative, the impregnation solution comprises, in addition to the solvent or solvents, only one or more compounds containing a group VIB metal, one or more compounds containing a group VIII metal, phosphorus, preferably in the form of phosphoric acid, and one or more organic compounds.

Typically, the organic compound is selected from compounds comprising one or more chemical functional groups selected from: carboxylic acid, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide functions, or also selected from compounds comprising a furan ring, or a sugar.

The oxygen-containing organic compound may be one or more selected from compounds comprising one or more chemical functional groups selected from: a carboxylic, alcohol, ether, aldehyde, ketone, ester or carbonate functional group, or also a compound comprising a furan ring, or also a sugar. For example, the oxygen-containing organic compound may be one or more selected from the following compounds: ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (molecular weight 200 to 1500g/mol), propylene glycol, 2-butoxyethanol, 2- (2-butoxyethoxy) ethanol, 2- (2-methoxyethoxy) ethanol, triglyme, glycerol, acetophenone, 2, 4-pentanedione, pentanone, acetic acid, maleic acid, malic acid, malonic acid, oxalic acid, gluconic acid, tartaric acid, citric acid, gamma-ketovaleric acid, succinic acid bis (C)₁-C₄Alkyl) esters, and more particularly dimethyl succinate, methyl acetoacetate, ethyl acetoacetate, 2-methoxyethyl 3-oxobutyrate, 2-methacryloyloxyethyl 3-oxobutyrate, dibenzofuran, crown ethers, phthalic acid, glucose, fructose, sucrose, sorboseAlcohol, xylitol, gamma-valerolactone, 2-acetylbutyrolactone, propylene carbonate, 2-furfural (also known as furfural), 5-hydroxymethylfurfural (also known as 5- (hydroxymethyl) -2-furfural or 5-HMF), 2-acetylfuran, 5-methyl-2-furfural, methyl 2-furoate, furfuryl alcohol (also known as furfuryl alcohol), furfuryl acetate, ascorbic acid, butyl lactate, butyl butyryl lactate, ethyl 3-hydroxybutyrate, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and 5-methyl-2 (3H) -furanone.

The nitrogen-containing organic compound may be one or more selected from compounds comprising one or more chemical functional groups selected from amine or nitrile functional groups. For 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, and carbazole.

The oxygen-and nitrogen-containing organic compound may be one or more selected from compounds comprising one or more chemical functional groups selected from carboxylic acid, alcohol, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, amide, urea or oxime functional groups. For example, the oxygen and nitrogen containing organic compound may be one or more selected from the group consisting of: 1, 2-cyclohexanediaminetetraacetic acid, Monoethanolamine (MEA), 1-methyl-2-pyrrolidone, dimethylformamide, ethylenediaminetetraacetic acid (EDTA), alanine, glycine, nitrilotriacetic acid (NTA), N- (2-hydroxyethyl) ethylenediamine-N, N ', N' -triacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), tetramethylurea, glutamic acid, dimethylglyoxime, N, N-dihydroxyethylglycine, tris (hydroxymethyl) methylglycine, 2-methoxyethyl cyanoacetate, 1-ethyl-2-pyrrolidone, 1-vinyl-2-pyrrolidone, 1, 3-dimethyl-2-imidazolidinone, 1- (2-hydroxyethyl) -2-pyrrolidone, 1- (2-hydroxyethyl) -2, 5-pyrrolidinedione, 1-methyl-2-piperidone, 1-acetyl-2-azepin, 1-vinyl-2-azepin, and 4-aminobutyric acid.

The sulfur-containing organic compound may be one or more selected from compounds comprising one or more chemical functional groups selected from thiol, thioether, sulfone or sulfoxide functional groups. For example, the sulfur-containing organic compound may be one or more selected from the group consisting of: thioglycolic acid, 2, 2' -thiodiethanol, 2-hydroxy-4-methylthiobutanoic acid, a sulfone derivative of benzothiophene or a sulfoxide derivative of benzothiophene, methyl 3- (methylthio) propionate and ethyl 3- (methylthio) propionate.

Preferably, the organic compound comprises oxygen; preferably, it is selected from gamma-valerolactone, 2-acetylbutyrolactone, triethylene glycol, diethylene glycol, ethylene glycol, ethylenediamine tetraacetic acid (EDTA), maleic acid, malonic acid, citric acid, gluconic acid, dimethyl succinate, glucose, fructose, sucrose, sorbitol, xylitol, gamma-ketovaleric acid, dimethylformamide, 1-methyl-2-pyrrolidone, propylene carbonate, 2-methoxyethyl 3-oxobutyrate, N-dihydroxyethylglycine, tris (hydroxymethyl) methylglycine, 2-furfural (also known as furfural), 5-hydroxymethylfurfural (also known as (5- (hydroxymethyl) -2-furfural or 5-HMF), 2-acetylfuran, 5-methyl-2-furfural, ascorbic acid, butyl lactate, ethyl 3-hydroxybutyrate, ethyl 3-ethoxypropionate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-hydroxyethyl acrylate, 1-vinyl-2-pyrrolidone, 1, 3-dimethyl-2-imidazolidinone, 1- (2-hydroxyethyl) -2-pyrrolidone, 1- (2-hydroxyethyl) -2, 5-pyrrolidinone, 5-methyl-2 (3H) -furanone, 1-methyl-2-piperidone and 4-aminobutyric acid.

The contacting step b) includes various embodiments. They differ in particular in the time when the organic compound is introduced when present and it can be carried out simultaneously with (co-impregnation) or after (post-impregnation) or before (pre-impregnation) the impregnation of the group VIB metal-containing compound. In addition, the embodiments may be combined.

Advantageously, after each impregnation step, whether it is a step of impregnating the metal and optionally the phosphorus or organic compound, the impregnated support is matured.

Any maturation step is advantageously carried out at atmospheric pressure, in a water-saturated atmosphere and at a temperature of 17 ℃ to 50 ℃, and preferably at ambient temperature. In general, a maturation time of ten minutes to forty-eight hours, and preferably of thirty minutes to six hours, is sufficient.

Any of the impregnation solutions described in the present invention may comprise any polar solvent known to those skilled in the art. The polar solvent used is advantageously selected from methanol, ethanol, water, phenol and cyclohexanol, used alone or as a mixture. The polar solvent may also advantageously be chosen from propylene carbonate, DMSO (dimethyl sulfoxide), N-methylpyrrolidone (NMP) and sulfolane, used alone or as a mixture. Preferably, a polar aprotic solvent is used. List of commonly used polar solvents and their dielectric constants can be found in booksSolvents and Solvent Effects in Organic ChemistryC, Reichardt, Wiley-VCH, third edition, 2003, 472-. Very preferably, the solvent used is water or ethanol, and particularly preferably the solvent is water. In one possible embodiment, no solvent may be present in the impregnation solution.

Drying (step c)

According to the drying step c) of the method of restoring activity of the invention, the catalyst of restored activity obtained in step b) is subjected to a drying step at a temperature of less than 200 ℃, advantageously between 50 ℃ and 180 ℃, preferably between 70 ℃ and 150 ℃, very preferably between 75 ℃ and 130 ℃.

The drying step is preferably carried out under an inert atmosphere or an oxygen-containing atmosphere. The drying step may be carried out by any technique known to those skilled in the art. Advantageously, it is carried out at atmospheric pressure or under reduced pressure. Preferably, this step is carried out at atmospheric pressure. Advantageously, it is carried out in a transverse bed (diverted bed) using hot air or any other hot gas. Preferably, when drying is carried out on a fixed bed, the gas used is air or an inert gas, such as argon or nitrogen. Very preferably, the drying is carried out in the presence of nitrogen and/or air in a transverse bed. Preferably, the duration of the drying step is from 5 minutes to 15 hours, preferably from 30 minutes to 12 hours.

According to a first alternative form, and advantageously, when an organic compound is present, drying is carried out so as to preferably maintain at least 30% by weight of the organic compound introduced during the impregnation step; preferably, the amount is greater than 50 wt%, and more preferably greater than 70 wt%, calculated on the residual carbon on the reactivated catalyst.

At the end of the drying step c), a catalyst is then obtained which regains activity and which is subjected to an optional activation (sulfidation) step for subsequent use in the process for the hydrodesulphurization of gasoline.

Calcination (optional step d)

According to another alternative, at the end of the drying step c), the calcination step d) is carried out at a temperature of between 200 ℃ and 600 ℃, preferably between 250 ℃ and 550 ℃, under an inert atmosphere (for example nitrogen) or under an atmosphere containing oxygen (for example air). The duration of this heat treatment is generally from 0.5 to 16 hours, preferably from 1 to 5 hours. After this treatment, the active phase is thus found in the form of oxides and, when the catalyst is introduced, the catalyst contains no or little organic compounds. However, the introduction of organic compounds during their preparation makes it possible to enhance the dispersion of the active phase, thus producing a more active and/or selective catalyst.

Vulcanization (optional step)

The reactivated catalyst of the process according to the invention is generally subjected to a sulfurization step before being brought into contact with the feed to be treated in the process for the hydrodesulphurization of gasolines. Sulfidation is preferably in a sulfur reducing medium, i.e. in H₂S and hydrogen to convert metal oxides to sulfides, such as, for example, MoS₂And Co₉S₈. Sulfidation is carried out by reacting a catalyst containing H in the presence of hydrogen₂S and hydrogen or can be decomposed to produce H₂A stream of sulfur compounds of S is injected onto the catalyst. Polysulfides, such as dimethyl disulfide (DMDS), are H commonly used in sulfide catalysts₂An S precursor. Sulfur may also be derived from the feed. Adjusting the temperature to make H₂S reacts with the metal oxide to form a metal sulfide. This sulfidation may be carried out at a temperature of from 200 ℃ to 600 ℃, more preferably from 300 ℃ to 500 ℃, in the reactor of the process according to the inventionIn situ or ex situ (inside or outside the reactor).

Hydrodesulfurization process

The invention also relates to a process for the hydrodesulphurization of a gasoline fraction containing sulphur olefins, in which the gasoline fraction, hydrogen and a catalyst which has regained activity according to the process of the invention are contacted, the process being carried out at a temperature of from 200 ℃ to 400 ℃, preferably from 230 ℃ to 330 ℃, and at a total pressure of from 1 to 3MPa, preferably from 1.5 to 2.5MPa, and a space-time velocity (HSV), defined as the flow rate of the volume of feed relative to the volume of catalyst, of from 1 to 10h^-1Preferably 2 to 6h^-1And the hydrogen/gasoline feed volume ratio is between 100 and 1200Sl/l, preferably between 150 and 400 Sl/l.

The hydrodesulphurization process according to the invention allows the conversion of organic sulphur compounds of the gasoline fraction into hydrogen sulphide (H)₂S) while limiting as much as possible the hydrogenation of the olefins present in said fraction.

Feed to be treated

The process according to the invention allows the treatment of any type of sulphur-containing olefinic gasoline fraction, such as, for example, fractions resulting from coking, visbreaking, steam cracking or catalytic cracking (FCC, fluid catalytic cracking) units. Such gasoline may optionally consist of a significant portion of gasoline from other production processes or conversion processes (coker or steam cracked gasoline), such as atmospheric distillation (direct distillation produced gasoline (or straight run gasoline)). The feed preferably consists of a gasoline fraction produced by a catalytic cracking unit.

The feed is a sulphur-containing olefinic gasoline fraction, typically boiling in the range of from the boiling point of a (C2 or C3) hydrocarbon having 2 or 3 carbon atoms up to 260 ℃, preferably from the boiling point of a (C2 or C3) hydrocarbon having 2 or 3 carbon atoms up to 220 ℃, more preferably from the boiling point of a hydrocarbon having 5 carbon atoms up to 220 ℃. The process according to the invention can also treat feeds having lower endpoints than those mentioned above, such as, for example, C5-180 ℃ fractions.

The sulfur content of gasoline fractions produced by catalytic cracking (FCC) depends on the sulfur content of the feed treated by FCC, whether the FCC feed has been pretreated and the end point of the fractions. Generally, the sulfur content of the entire gasoline fraction, particularly those derived from FCC, is greater than 100 weight ppm, and most of the time greater than 500 weight ppm. For gasolines with an endpoint greater than 200 ℃, the sulfur content is typically greater than 1000 ppm by weight; in some cases they may even reach values on the order of 4000 to 5000 ppm by weight.

In addition, gasoline obtained from a catalytic cracking (FCC) unit contains on average 0.5 to 5 wt% dienes, 20 to 50 wt% olefins and 10 to 0.5 wt% sulfur, typically less than 300ppm mercaptans. Mercaptans are generally concentrated in the light fraction of gasoline and, more specifically, in the fraction whose boiling point is less than 120 ℃.

It should be noted that the sulfur compounds present in gasoline may also comprise heterocyclic sulfur compounds, such as, for example, thiophenes, alkylthiophenes or benzothiophenes. These heterocyclic compounds, unlike thiols, cannot be removed by extraction methods. These sulfur compounds are thus hydrotreated (resulting in their conversion to hydrocarbons and H)₂S) is removed.

Preferably, the gasoline treated by the process according to the invention is a heavy gasoline (or HCN, for "heavy cracked naphtha") resulting from a distillation step, the purpose of which is to separate a wide cut of gasoline (or FRCN, for "full range cracked naphtha") resulting from the cracking process into light gasoline (LCN, light cracked naphtha) and heavy gasoline HCN. The cut points for light and heavy gasolines are determined to limit the sulfur content of the light gasoline and to make it available for use in the gasoline pool, preferably without additional post-treatment. Advantageously, the wide cut FRCN is subjected to a selective hydrogenation step as described below prior to the distillation step.

The hydrodesulfurization process can be carried out in one or more reactors of the fixed bed type or of the ebullating bed type, connected in series. If the process is carried out by means of at least two reactors connected in series, it is possible to provide a process for removing H from the effluent resulting from the first hydrodesulfurization reactor (before the treatment of said effluent in the second hydrodesulfurization reactor)₂And S.

The hydrodesulphurisation process according to the invention is carried out in the presence of a catalyst which restores activity. It can also be carried out in the presence of a mixture of reactivated catalyst and fresh or regenerated catalyst.

When present, the fresh or regenerated catalyst comprises at least one group VIIl metal, at least one group VIB metal and an oxidic support, and optionally phosphorus and/or an organic compound as described above.

The active phase and support of the fresh or regenerated catalyst may be the same or different from the active phase and support of the reactivated catalyst.

The active phase and support of the fresh catalyst may be the same or different from the active phase and support of the regenerated catalyst.

When the hydrodesulphurization process is carried out in the presence of a catalyst with restored activity and of a fresh or regenerated catalyst, it can be carried out in a reactor of the fixed bed type comprising a plurality of catalytic beds.

In this case, and according to a first alternative, the catalytic bed containing fresh or regenerated catalyst may precede the catalytic bed containing the catalyst of restored activity, in the direction of circulation of the feed.

In this case, and according to a second alternative, the catalytic bed containing the catalyst with restored activity may precede the catalytic bed containing the fresh or regenerated catalyst, in the direction of circulation of the feed.

In this case, and according to a third alternative, the catalytic bed may comprise a mixture of reactivated catalyst and fresh catalyst and/or regenerated catalyst.

In these cases, the operating conditions are those described above. They are generally identical in the different catalytic beds except for the temperature, which generally increases in the catalytic beds as the hydrodesulfurization reaction exotherms.

When the hydrodesulfurization process is carried out in the presence of a reactivated catalyst and fresh or regenerated catalyst in a plurality of reactors of the fixed bed or ebullated bed type connected in series, one reactor may contain the reactivated catalyst and the other reactor may contain the fresh catalystThe catalyst or regenerated catalyst, or a mixture of reactivated catalyst with fresh catalyst and/or regenerated catalyst, and this in any order. There may be provided a process for removing H from the effluent produced in a first hydrodesulfurization reactor prior to treating the effluent in a second hydrodesulfurization reactor₂And S. In these cases, the operating conditions are as described above and may be the same or different in different reactors.

Selective hydrogenation (optional step)

According to an alternative form, the gasoline fraction is subjected to a selective hydrogenation step before the hydrodesulphurization process according to the invention.

Preferably, the gasoline treated by the hydrodesulfurization process according to the invention is a heavy gasoline resulting from a distillation step aimed at separating the wide gasoline fraction resulting from the cracking process (or FRCN, for "full range cracked naphtha") into a light gasoline and a heavy gasoline.

Advantageously, the wide FRCN fraction is subjected to a selective hydrogenation step as described below prior to the distillation step.

The FRCN fraction is pretreated in the presence of hydrogen and a selective hydrogenation catalyst to at least partially hydrogenate the diolefins and to react for increasing the molecular weight of a portion of the mercaptan (RSH) compounds present in the feed (to form thioethers by reaction with olefins).

To this end, the broad FRCN fraction is fed to a selective hydrogenation catalytic reactor containing at least one fixed or moving catalyst bed for the selective hydrogenation of dienes and for increasing the molecular weight of mercaptans. The reactions for the selective hydrogenation of diolefins and for increasing the molecular weight of mercaptans are preferably carried out over a sulfided catalyst comprising at least one group VIII element and optionally at least one group VIB element and an oxidic support. The group VIII element is preferably selected from nickel and cobalt, especially nickel. When present, the group VIB element is preferably selected from molybdenum and tungsten, and very preferably molybdenum.

The oxide support of the catalyst is preferably selected from the group consisting of alumina, nickel aluminate, dioxygenSilicon carbide or mixtures of these oxides. Preferably, alumina is used, and more preferably, high purity alumina is used. According to a preferred embodiment, the selective hydrogenation catalyst comprises nickel in a weight content ranging from 1% to 12% of nickel oxide (in the form of NiO) and molybdenum oxide (MoO) in a weight content ranging from 6% to 18%₃Form) a weight content comprising molybdenum and a nickel/molybdenum molar ratio of between 0.3 and 2.5, wherein the metal is deposited on a support consisting of alumina and wherein the degree of sulphidation of the metal constituting the catalyst is greater than 50%.

During the optional selective hydrogenation step, the gasoline is contacted with the catalyst at a temperature of from 50 ℃ to 250 ℃, preferably from 80 ℃ to 220 ℃ and more preferably from 90 ℃ to 200 ℃, with a liquid air velocity (LHSV) of 0.5h^-1-20h^-1The liquid air velocity is given in units of liters of feed per liter of catalyst per hour (l/l.h). The pressure is from 0.4MPa to 5MPa, preferably from 0.6 to 4MPa, and still more preferably from 1 to 2 MPa. The optional selective hydrogenation step typically employs 2 to 100Sm³Hydrogen/m³Feed, preferably 3 to 30Sm³Hydrogen/m³H of feed₂The/gasoline feed ratio was carried out.

Examples

Example 1-preparation of freshly calcined catalyst A (comparative)

The support of catalyst A is a catalyst having a particle size of 140m²Specific surface area per gram, 1.0cm³Transition alumina in pore volume/g. Catalyst a was prepared by dry impregnation of the support with an aqueous solution of ammonium heptamolybdate and cobalt nitrate, the volume of the solution containing the metal precursor being strictly equal to the pore volume of the support material. The concentration of the metal precursor in the aqueous solution is adjusted to obtain the desired weight percent of molybdenum and cobalt on the final catalyst. After dry impregnation on the support, the catalyst was left to mature in a water-saturated chamber for 1 hour 30 minutes, dried in an oven at 90 ℃ under air for 12 hours, and then calcined in air at 450 ℃ for 2 hours.

The fresh catalyst A obtained after calcination had a content of 9.6% by weight of molybdenum (MoO)₃Equivalent) and 2.2 wt% cobalt (CoO equivalent). Co/Mo atomic ratio of 0.44 and specific surface area of 123m of catalyst/g。

Example 2-preparation of regenerated calcined catalyst A (comparative)

Fresh catalyst a was used to desulfurize catalytically cracked (FCC) gasoline and its characteristics are listed in table 1. The reaction was carried out in a transverse bed type reactor at 270 ℃ for 900 hours under the following conditions: p =2MPa, HSV =4h^-1，H₂/HC =300 liters per liter of hydrocarbon feed. The catalyst was pretreated at 350 ℃ with a feed containing 4% by weight of sulfur in the form of DMDS (dimethyldisulfide) to sulfide the oxide phase. The reaction was carried out in an isothermal pilot reactor in an upward stream.

TABLE 1

S ppm	392
		Aromatic hydrocarbons wt.%	41.3
Paraffin wax wt%	27.2
		Cycloalkane wt%	11.0
Olefin wt%	20.5
		T5℃	62
T95℃	225

After the completion of the hydrodesulfurization of the above-mentioned catalytically cracked (FCC) gasoline, the spent catalyst a was taken out of the reactor. The spent catalyst A was subsequently washed with toluene in a Soxhlet extractor (Soxhlet) at 250 ℃ for 7 hours (deoiling).

The regeneration of the spent/washed catalyst a was then carried out in a tubular oven at 450 ℃ for 2 hours in dry air and a regenerated catalyst a was obtained. The residual carbon content of regenerated catalyst A was zero.

Example 3-preparation of calcined, activity-restored catalyst B1 by addition of Co and Mo (not according to the invention)

Catalyst B1 was prepared by dry impregnation of regenerated catalyst a with an aqueous solution of ammonium heptamolybdate and cobalt nitrate, the volume of the solution containing the metal precursor being strictly equal to the pore volume of the charge of the regenerated catalyst a. The concentration of the metal precursor in the aqueous solution is adjusted to obtain the desired weight percent of molybdenum and cobalt on the final catalyst. After dry impregnation on regenerated catalyst a, catalyst B1 was aged for 1 hour 30 minutes in a chamber saturated with water and dried in an oven at 90 ℃ for 12 hours in air, and then calcined at 450 ℃ for 2 hours in air.

The catalyst B1 obtained after calcination had a molybdenum content (MoO) of 10.8% by weight₃Equivalent), and a cobalt content of 2.4% by weight (CoO equivalent), a Co/Mo atomic ratio of 0.43, and 122m²Specific surface area in g. The molar ratio of the group VIB metal added to the group VIB metal already present in the regenerated catalyst a was 0.125 mol/mol.

Example 4-preparation of a dried, Activity-restoring catalyst B2 by addition of Co and Mo (according to the invention)

Catalyst B2 was prepared by dry impregnation of regenerated catalyst a with an aqueous solution of ammonium heptamolybdate and cobalt nitrate, the volume of the solution containing the metal precursor being strictly equal to the pore volume of the material of regenerated catalyst a. The concentration of the metal precursor in the aqueous solution is adjusted to obtain the desired weight percent of molybdenum and cobalt on the final catalyst. After dry impregnation on regenerated catalyst a, catalyst B2 was aged for 1 hour 30 minutes in a room saturated with water and dried in an oven at 90 ℃ for 12 hours in air.

The molybdenum content of the dried catalyst B2 was 13.8 wt.% (MoO)₃Equivalent), and a cobalt content of 3.6% by weight (CoO equivalent), a Co/Mo atomic ratio of 0.50, and a specific surface area of 116m²(ii) in terms of/g. The molar ratio of the group VIB metal added to the group VIB metal already present in the regenerated catalyst a was 0.44 mol/mol.

Example 5-preparation of calcined, activity-restoring catalyst B3 by addition of Co and Mo (according to the invention)

Catalyst B3 was obtained by calcining catalyst B2 in air at 450 ℃ for 2 hours.

Example 6-preparation of catalyst B4 for restoration of Activity by addition of Co, Mo and P (according to the invention)

Catalyst B4 was prepared by dry impregnation of regenerated catalyst a with an aqueous solution of molybdenum oxide, cobalt hydroxide and orthophosphoric acid, the volume of the solution containing the metal precursor being strictly equal to the pore volume of the mass of the regenerated catalyst a. The concentration of the metal precursor in the aqueous solution is adjusted to obtain the desired weight percentages of molybdenum, cobalt and phosphorus on the final catalyst. After dry impregnation on regenerated catalyst a, catalyst B4 was aged for 1 hour 30 minutes in a chamber saturated with water and dried in an oven at 120 ℃ for 12 hours under air.

The catalyst B4 obtained after drying had a molybdenum (MoO) content of 12.4% by weight₃Equivalent), 2.6% by weight of cobalt (CoO equivalent) and 1.2% by weight of phosphorus (P)₂O₅Equivalent), the atomic ratio Co/Mo was 0.40, the atomic ratio P/Mo was 0.20, and the specific surface area was 117 m/g. The molar ratio of the group VIB metal added with respect to the group VIB metal already present in the regenerated catalyst a was 0.3 mol/mol.

Example 7-preparation of catalyst for restoring Activity by addition of Co, Mo, P and citric acid B5 (according to the invention)

Catalyst B5 was prepared by dry impregnation of the regenerated catalyst a with an aqueous solution of molybdenum oxide, cobalt hydroxide, orthophosphoric acid and citric acid, the volume of the solution containing the metal precursor being strictly equal to the pore volume of the mass of regenerated catalyst a. The concentration of the metal precursor in the aqueous solution is adjusted to obtain the desired weight percentages of molybdenum, cobalt and phosphorus on the final catalyst. The molar ratio of citric acid to molybdenum on the final catalyst was 0.4. After dry impregnation on regenerated catalyst a, catalyst B5 was aged for 1 hour 30 minutes in a room saturated with water and dried in an oven at 120 ℃ in air for 12 hours under air.

The catalyst B5 obtained after drying had a molybdenum (MoO) content of 15.5% by weight₃Equivalent), 3.4% by weight of cobalt (CoO equivalent) and 2.4% by weight of phosphorus (P)₂O₅Equivalent), the atomic ratio Co/Mo was 0.42, the atomic ratio P/Mo was 0.31, and the specific surface area was 110 m/g. The molar ratio of the group VIB metal added to the group VIB metal already present in the regenerated catalyst A was 0.61 mol/mol.

Example 8 evaluation of the quality of the catalytic performances of catalyst A (regenerated), B1, B2, B3, B4 and B5

A model feed representing catalytically cracked (FCC) gasoline containing 10 wt% 2, 3-dimethylbut-2-ene and 0.33 wt% 3-methylthiophene (i.e., 1000 ppm by weight sulfur in the feed) was used to evaluate the quality of catalytic performance of various catalysts. The solvent used was heptane.

The Hydrodesulfurization (HDS) reaction was carried out in a fixed transverse bed reactor at a total pressure of 1.5MPa, with HSV =6h at 210%^-1(HSV = feed volumetric flow rate/catalyst volume) and H of 300 Sl/l₂Volume ratio/feed in the presence of 4 ml of catalyst. Before HDS reaction, under atmospheric pressure, in the presence of 15 mol% H₂S under a stream of hydrogen, the catalyst was sulfided in situ at 350 ℃ for 2 hours.

Each catalyst was placed in the reactor in turn. Samples were taken at different time intervals and analyzed by gas chromatography to observe the disappearance of the reactants and the formation of the product.

The quality of the catalytic performance of the catalyst was evaluated in terms of catalytic activity and selectivity. Hydrodesulfurization (HDS) activity is represented by the HDS reaction rate constant (kHDS) of 3-methylthiophene, normalized to the volume of catalyst introduced (and assuming first order kinetics with respect to the kinetics of the sulfur compounds). The olefin hydrogenation (HydO) activity is expressed as the rate constant for the hydrogenation of 2, 3-dimethylbut-2-ene, normalized to the volume of catalyst introduced (and assuming first order kinetics with respect to the olefin).

The selectivity of the catalyst is expressed by the normalized ratio of rate constants kHDS/kHydO. The higher the selectivity of the catalyst, the higher the kHDS/kHydO ratio. The values obtained were normalized by taking regenerated catalyst a as reference (relative HDS activity and relative selectivity equal to 100). Thus, the quality of performance is relative HDS activity and relative selectivity.

TABLE 2

Catalysts	Relative HDS Activity	Relative selectivity
			A (regeneration) (comparison)	100	100
B1 (comparison)	101	98
			B2 (according to the invention)	105	107
B3 (according to the invention)	109	107
			B4 (according to the invention)	115	120
B5 (according to the invention)	122	135

Compared to the comparative catalysts a (regenerated) and B1, the catalysts B2, B3, B4 and B5, which recovered activity with respect to the hydrogenation of olefins, had greater activity and improved selectivity in hydrodesulfurization.

This improvement in catalyst selectivity is particularly advantageous in the case of processes for the hydrodesulfurization of olefin-containing gasolines, for which it is desirable to limit as far as possible the octane loss due to hydrogenation of the olefins.