FR2785833A1 - Nickel based catalyst and its use in the dehydrosulfuration of hydrocarbonaceous charges - Google Patents

Abstract

A catalyst comprising of 1-80 wt.% Ni is used for the dehydrosulfuration of hydrocarbonaceous charges. The Ni is at least partially sulfurated.

Description

The present invention relates to a hydrodesulfurization catalyst for hydrocarbon feedstocks, preferably gasolines, and more preferably catalytic cracking gasolines (FCC or Fluid Catalytic Cracking), making it possible to carry out the hydrodesulfurization of said charge with a minimum drop in the octane number. and / or olefin content
The production of reformulated essences meeting the new environmental standards requires in particular that the concentration of aromatics (especially benzene) and sulfur in all its forms (sulfide, alkylthiophene or mercaptan) be reduced. Some gasolines, in particular catalytic cracked gasolines have high olefin contents, thus the sulfur present in reformulated gasolines is attributable to almost 90% to catalytic cracked gasoline (FCC). Desulfurization of gasolines is therefore of increasing importance.

 The hydrotreatment of the feedstock sent to catalytic cracking leads to gasolines typically containing 100 ppm of sulfur. The units for hydrotreating catalytic cracking feeds, however, operate under severe temperature and pressure conditions, which requires a significant investment effort. In addition, the entire charge must be desulphurized, which entails the treatment of very large charge volumes.

 The hydrotreatment (or hydrodesulfurization) of catalytic cracking essences carried out under conventional conditions known to those skilled in the art makes it possible to reduce the sulfur content of the cut. However, this process has the major drawback of causing a very significant drop in the octane number of the cut, due to the saturation of all or a significant part of the olefins.

 Hydrotreatment processes for FCC gasolines have already been proposed. For example, patent US Pat. No. 5,290,427 describes a method consisting in fractioning the gasoline, desulfurizing the fractions and converting the gasoline fraction onto an acid solid in order to to compensate for the loss of octane.

 US-A-5 318 690 proposes a process with a fractionation of gasoline, a softening of the light fraction, while the heavy fraction is hydrodesulfurized, then converted to zeolite ZSM-5 and desulfurized again under mild conditions . This technique is based on a separation of the crude petrol so as to obtain a light cut practically free of sulfur compounds other than mercaptans, so as to treat the cut only by means of a softening making it possible to remove the mercaptans. Therefore, the heavy cut contains a relatively large amount of olefins which are partially saturated during hydrotreatment. To avoid the loss of octane index linked to the hydrogenation of olefins, the patent recommends cracking on ZSM-5 so as to produce olefins.

However, this cracking reaction also leads to the production of light products, production responsible for the drop in overall gasoline yield. In addition, these olefins can, in the presence of H2S, form mercaptans, which has the disadvantage of calling for additional softening or even desulfurization.

 Another way commonly used by the refiner to deal with this problem of the sulfur level in gasolines is to separate the boiling point fraction of at least 180 C, which contains most of the sulfur compounds other than mercaptans. This fraction is then downgraded, that is to say mixed with an LCO cut ("light cycle oil") and is generally not valued; it can however be used as a charge diluent.

 An advantageous means would be to treat all of the gasoline on a selective catalyst, that is to say a catalyst which makes it possible to achieve significant desulfurization rates (greater than 70%) by limiting the conversion of olefins (30%). to minimize octane losses.

 In general, the catalysts used for this type of application are catalysts of the sulfide type containing an element of the Vlb group (chromium, molybdenum, tungsten) and an element of the Vill group (iron, ruthenium, osmium, cobalt, rhodium, iridium , nickel, palladium, platinum).

 The main drawback of these catalysts is low selectivity, that is to say that it is difficult to access, with this type of catalyst, high desulfurization rates (greater than 70%) by limiting the hydrogenation of olefins. In addition, these catalysts lead, when the desulfurization is not complete, to the formation of mercaptans which require an additional softening treatment, which increases the overall cost of the operation.

 Furthermore, to limit the hydrogenation of olefins and the formation of mercapatans it is necessary to work with high hydrogen / charge ratios in order to lower the partial pressure of H2S. One solution described in patent application EP-A-0 755 995 consists in carrying out the desulfurization reaction in two stages, using hydrogen free of H2S for each of the stages. This operation leads to an increased complexity of operations which makes this solution unattractive.

 It has also been described in patent application EP-A-0 745 660, that deposition of carbonaceous species on the surface of the catalyst makes it possible to minimize the hydrogenation of olefins.

 In addition, it is indicated in French patent application 98/02 945 that the use of high hydrogen flow rates makes it possible to lower the partial pressure of olefins and thus limit their hydrogenation.

On the other hand, the addition of alkali or alkaline earth metals (patent application
EP-A-0 736 589) or the use of weakly acidic support (patent US-A-4,334,982), as well as the addition of nitrogenous compounds in the feed (patent US-A-4,314,901), present the advantage of increasing the selectivity with respect to the hydrogenation of olefins and also of increasing the stability of the catalyst.

 A catalyst has now been found which makes it possible to reduce the total sulfur and mercaptan contents of hydrocarbon cuts, preferably of gasoline cuts at very low levels, without loss of yield, for example in gasoline, and by minimizing the reduction in octane number.

 The feed is preferably a gasoline, more preferably a catalytic cracking gasoline, that is to say a gasoline from a catalytic cracking unit, the range of boiling points of which typically extends from C5 up to 220 C. The end point of the petrol cut depends of course on the refinery and market constraints, but generally remains within the limits indicated above.

 The hydrodesulfurization catalysts according to the invention are catalysts comprising nickel, preferably supported, the nickel content of which is generally between approximately 1 and approximately 80% by weight.

 The nickel content of the catalyst according to the invention is generally from 1 to 80% by weight, preferably from 5 to 70% by weight and, even more preferably, from 10 to 50% by weight. Preferably, the catalyst is shaped in the form of beads, extrudates, pellets, or trilobes. The nickel can be incorporated into the catalyst on the preformed support, or mixed with the support before the shaping step. Nickel is generally introduced in the form of a precursor salt, generally soluble in water, such as, for example, nickel nitrate. This mode of introduction is not specific to the invention. Any other mode of introduction known to those skilled in the art is suitable for the invention.

 The catalyst supports according to the invention are generally porous solids chosen from refractory oxides, such as, for example, aluminas, silicas and silica-aluminas, magnesia, as well as titanium oxide and zinc, the latter oxides being able to be used alone or as a mixture with alumina or silica-alumina. Preferably, the supports are transition aluminas or silicas whose specific surface is between approximately 25 and approximately 350 m2 / g, preferably between 80 and 250 m2 / g. The supports chosen from natural compounds (for example kieselguhr or kaolin) may also be suitable as supports for the catalysts according to the invention.

 After the introduction of nickel and possibly shaping of the catalyst (when this step is carried out on a mixture already containing nickel), the catalyst is activated. This activation can correspond either to an oxidation, then to a reduction, or to a direct reduction, or to a calcination only. The calcination step is generally carried out at temperatures ranging from approximately 100 to approximately 600 ° C. and preferably from 200 to 450 ° C., under an air flow. The reduction step is carried out under conditions making it possible to convert at least part of the oxidized forms of nickel to metal. Generally, it consists in treating the catalyst under a stream of hydrogen at a temperature at least equal to 300 C. The reduction can also be carried out in part by means of chemical reducing agents.

 The catalyst is preferably used at least in part in its sulfurized form. This makes it possible to minimize the risks of hydrogenation of unsaturated compounds such as olefins or aromatic compounds during the start-up phase. The introduction of sulfur can occur between different activation stages. Preferably, no oxidation step is carried out when the sulfur or a sulfur-containing compound is introduced onto the catalyst. The sulfur or a sulfur-containing compound can be introduced ex situ, that is to say outside the reactor where the process according to the invention is carried out, or in situ, that is to say in the reactor used for the method according to the invention. In the latter case, the catalyst is preferably reduced under the conditions described above, then sulphurized by passing a charge containing at least one sulfur compound, which once decomposed leads to the fixation of S on the catalyst. This charge can be gaseous or liquid, for example hydrogen containing H 2 S, or a liquid containing at least one sulfur-containing compound.

Preferably, the sulfur-containing compound is added to the catalyst ex situ. For example, after the calcination step, a sulfur-containing compound can be introduced onto the catalyst in the optional presence of another compound. The catalyst is then dried, then transferred to the reactor used to use the catalyst according to the invention. The catalyst is then treated under hydrogen in this reactor, in order to transform at least part of the nickel into sulphide. A procedure which is particularly suitable for the invention is that described in patents FR-B-2 708 596 and
FR-B-2 708 597.

 Thus, preferably the nickel can be sulphurized with at least one sulfur compound contained in a solvent. Preferably, the sulfur compound is chosen from the group consisting of organic alkyl or aryl sulphides, organic arylaryl or arylalkyl sulphides, thiols, thiodiazoles, organic thioacids, thioramides, thioesters, thiophenols, mercapto-alcohols , monothioglycols.

 Furthermore, the solvent used during the sulfurization of nickel may preferably be chosen from the group formed by gasolines, alcohols, aldehydes, ketones, ethers, alcohols, polyalcohols, acids, polyacids, t and glycols.

 After sulfurization, the sulfur content of the catalyst is generally between approximately 0.5 and approximately 25% by weight, and preferably between 4 and 20% by weight.

 The catalyst according to the invention is used in a process consisting of hydrodesulfurization, optionally preceded by a selective hydrogenation of the diolefins.

 The operating conditions of the hydrodesulfurization according to the present invention are adjusted so as to reach the desired level of hydrodesulfurization, and in order to minimize the loss of octane resulting from the saturation of the olefins.

 Hydrodesulfurization is carried out at a temperature between about 160 C and 420 C, under a low pressure between about 0.5 and about 8 MPa, the space velocity of the liquid is between about 0.5 and about 10 h-1 , the H2 / HC ratio is between about 100 and about 600 liters per liter.

 The catalyst used in the process according to the invention generally makes it possible to convert at most 70% of the olefins, preferably at most 60-65% of the olefins, and more preferably less than 20% of the olefins (the diolefins being totally or practically completely hydrogenated ). With the catalyst according to the invention, it is thus possible to achieve high hydrodesulfurization rates while limiting the loss of olefins and therefore the reduction in the octane number.

 The effluent obtained may possibly be stripped to eliminate the H2S produced by the desulfurization.

 In the process using the catalyst according to the invention, the feedstock, for example the crude gasoline is either treated directly, or fractionated into at least one light section with a boiling point (end point) less than or equal to about 160 C, containing the major part of olefins and mercaptans, and at least one heavy fraction. Light cutting (or light fraction) at an end point less than or equal to 160 C, advantageously less than or equal to 140 C, preferably less than or equal to 120 C.

The cutting point is chosen so as to maximize the olefin content in the light cut. The light cut is relatively rich in olefins, while the heavier cut (or heavy fraction), relatively poor in olefins, concentrates the sulfur species and the aromatics.

 The sulfur species contained in the feeds treated by the process according to the invention can be mercaptans, sulfides or disulfides, heterocyclic compounds, such as for example thiophenes or alkyl-thiophenes, or even heavier compounds, such as benzothiophene example. These heterocyclic compounds, unlike mercaptans, cannot be removed by the extractive processes. They are therefore eliminated during the passage over the catalyst according to the invention which leads to their decomposition into hydrocarbons and H2S.

 The sulfur content of gasoline cuts produced by catalytic cracking (FCC) depends on the sulfur content of the feed treated at the FCC level, as well as the end point of the cut. Light fractions naturally have a lower sulfur content than heavier cuts. Generally, the sulfur contents of the entire fuel cut from the FCC are greater than 100 ppm by weight and most of the time greater than 500 ppm by weight. For gasolines having end points greater than 200 ° C., the sulfur contents are often greater than 1000 ppm by weight, possibly even in certain cases reaching values of the order of 4000 to 5000 ppm by weight.

 The treatments described below can be applied either to the entire gasoline cut, for example a catalytic cracked gasoline, or to the light cut and / or to the heavy cut in the case of fractionation. In the case where a fractionation is carried out, the operating conditions will be adjusted according to the desulfurization rates to be achieved and taking into account the differences in the reactivities of the different hydrocarbons which make up these cuts.

 The process steps in which the catalyst according to the invention is used are described in more detail below.

-Hydrogenation of dienes
The hydrogenation of dienes is an optional but advantageous step, which makes it possible to eliminate, before hydrodesulfurization, almost all of the dienes present in the gasoline fraction containing sulfur to be treated. It generally takes place in the presence of a catalyst comprising at least one metal from group VIII, preferably chosen from the group formed by platinum, palladium and nickel, and a support. Use will be made, for example, of a catalyst containing 1 to 20% by weight of nickel deposited on an inert support, such as, for example, alumina, silica, silica-alumina or a support containing at least 50% of alumina. . This catalyst operates under a pressure of 0.4 to 5 MPa, at a temperature of 50 to 250 C, with an hourly space velocity of the liquid from 1 to 10 h -1. Another metal can be combined to form a bimetallic catalyst, such as for example molybdenum or tungsten.

 It can be particularly advantageous, especially when treating cuts with a boiling point below 160 ° C., to operate under conditions such that at least partial softening of the gasoline is obtained, that is to say ie some reduction in the mercaptan content. To do this, one can use the procedure described in patent FR-B-2 753 717, which uses a catalyst based on palladium.

 The choice of operating conditions is particularly important. Most generally, it will be operated under pressure in the presence of a quantity of hydrogen in slight excess relative to the stoichiometric value necessary for hydrogenating the diolefins. The hydrogen and the feedstock to be treated are injected in ascending or descending currents into a reactor preferably having a fixed bed of catalyst. The temperature is more generally between approximately 50 and approximately 250 C, and preferably between 80 and 200 C, and more preferably between 160 and 190 C.

 The pressure is sufficient to maintain more than 80%, and preferably more than 95%, by weight of the gasoline to be treated in the liquid phase in the reactor; it is most generally between 0.4 and 5 MPa and preferably greater than 1 MPa. The pressure is advantageously between 1 and 4 MPa. The space velocity is between approximately 1 and approximately 10 h -1, preferably between 4 and 10 h -1.

 The light fraction of the catalytic cracking gasoline fraction can contain up to a few% by weight of diolefins. After hydrogenation, the content of diolefins is generally reduced to less than 3000 ppm, even less than 2500 ppm and more preferably less than 1500 ppm. In some cases, it can be obtained less than 500 ppm. The content of dienes after selective hydrogenation can even be reduced to less than 250 ppm if necessary.

 According to one embodiment of the invention, the hydrogenation step of the dienes takes place in a catalytic hydrogenation reactor which comprises a catalytic reaction zone traversed by the entire charge and the quantity of hydrogen necessary to carry out the desired reactions .

-Hydrodesulfurization
The hydrodesulfurization of a hydrocarbon fraction, preferably a petrol fraction, containing sulfur has the purpose, using the catalyst according to the invention, of converting the sulfur compounds of the fraction to H2S, so as to obtain an effluent corresponding to desired specifications in terms of sulfur compound content. The resulting cut has the same distillation range and a slightly lower octane number, due to the partial, but inevitable, saturation of the olefins.

 The operating conditions of the hydrodesulfurization reactor according to the present invention must be adjusted to reach the desired level of desulfurization, and above all to minimize the loss of octane resulting from the saturation of the olefins. Generally, at most 70% of the olefins are converted (the diolefins being totally or practically completely hydrogenated); preferably are converted at most 60-65% and more preferably less than 20% of the olefins. With the catalyst according to the invention, it is possible to achieve high desulfurization rates while limiting the loss of olefins and consequently the loss of octane number.

 The cut is subjected to hydrodesulfurization (hydrotreatment), in the presence of hydrogen, with the catalyst according to the invention at a temperature between about 160 C and about 420 C, preferably between 260 C and 380 C, and very preferred between 290 C and 350 C, under a low to moderate pressure, generally between about 0.5 and about 8 MPa. The space velocity of the liquid is between approximately 0.5 and approximately 10 h -1 (volume of liquid per volume of catalyst and per hour), preferably between 1 and 8 h -1. The H2 / HC ratio is adjusted as a function of the desulphurization rates desired between approximately 100 and approximately 600 liters per liter.

 When the entire gasoline cut is subjected to hydrotreatment (hydrodesulfurization), the temperature is advantageously between approximately 260 and approximately 380 C. The pressure is from approximately 1 to approximately 5 MPa, preferably from 1 to 4 MPa and more preferably 1.5 to 3 MPa.

 In the case where the catalytic cracking gasoline fraction has been fractionated, for example into two fractions: a light gasoline and a heavy gasoline, the operating conditions will be adjusted according to the desulfurization rates to be achieved and taking into account the differences in reactivity of the different hydrocarbons that make up said cut.

 The temperature of the hydrodesulfurization stage is preferably between 200 C and 400 C, very preferably between 290 C and 350 C for light cuts, preferably between 220 and 450 C, and very preferably between 300 C and 400 C for heavy cuts. The pressure used will be from approximately 1 to approximately 5 MPa, preferably from 1 to 3 MPa, for light cuts, and from approximately 1 to approximately 5 MPa, preferably from 2 to 4 MPa, for heavy cuts.

 The hydrodesulfurization process using the catalyst according to the invention can thus, for example, be implemented in a configuration which comprises, firstly the distillation of gasoline into two fractions: a light one, the point of which boiling is for example between 20 and 160 C, which contains the largest part of the olefins and part of the sulfur-containing compounds, and the other heavier, whose boiling point is for example greater than 160 C, and which contains the heaviest sulfur compounds and, as unsaturated compounds, few olefins but mainly aromatic compounds.

 Each of the two fractions is then subjected to hydrodesulfurization, under the conditions already described above, in order to eliminate almost completely the sulfur from the heavy fraction and to eliminate part of the sulfur present in the light fraction. In particular, it is preferable to limit the hydrodesulfurization so as to achieve the sulfur content necessary so that the product obtained, after mixing the two light and heavy cuts desulfurized, has a sulfur content corresponding to the desired specifications.

 Another possible implementation comprises, firstly, the distillation of the gasoline into two fractions, one light, the boiling point of which is for example 20 to 160 ° C., containing most of the olefins and part of the sulfur compounds, and the other, heavier, the boiling point of which is for example greater than 160 ° C., containing the heaviest sulfur compounds and, as unsaturated compounds, few olefins but mainly aromatic compounds.

 The light fraction is subjected to a mercaptan removal treatment, such as for example a softening described in the aforementioned patent documents. The second, heaviest fraction is subjected to hydrodesulfurization in the presence of the catalyst according to the invention, in order to at least partially remove the sulfur which it contains.

 Another configuration can also be implemented, in which the catalyst according to the invention is placed directly in the distillation zone allowing the separation of the light fraction from the heavy fraction. Another possible possibility is to place the reaction zone where the hydrodesulfurization takes place outside the distillation zone and to treat a liquid fraction taken from a tray of said distillation zone, with recycling of the desulfurized effluent. to said distillation zone, as described for example in patent application WO98 / 17610, at a level situated above or below, preferably in the vicinity of the level of sampling.

 The following examples illustrate the invention without limiting its scope.

Load used in the examples:
Table 1 shows the characteristics of the charge (catalytic cracking gasoline) treated in the examples which follow. The analysis methods used to characterize the loads and effluents are as follows:
- gas chromatography (CPG) for the constituents
hydrocarbons;
-Method NF M 07022 / ASTM D 3227 for mercaptans;
-Method NF M 07052 for total sulfur;
- method NF EN 25164 / M 07026-2 / ISO 5164 / ASTM D 2699 for the index
research octane;
- NF EN 25163 / M 07026-1 / ISO 5163 / ASTM D 2700 method for the index
engine octane.

Table 1: Characteristics of the load used
Charge
Density 0.73
Initial point (C) 26
End point (C) 184
olefin content (% by weight) 37.7
iBr (gBr / 100g) 53
S total (ppm) 1000
S ex mercaptans (ppm) 3
RON 89.8
MY 79.2
(RON + MON) / 2 84.5
Example 1 (according to the invention): Preparation of catalyst A
Catalyst A is prepared from a transition alumina of 140 m2 / g in the form of a ball 2 mm in diameter. The pore volume is 1 ml / g of support.

 1 kg of support is impregnated with 1 liter of nickel nitrate solution. The catalyst is then dried at 120 ° C. and calcined under a stream of air at 400 ° C. for one hour. The nickel content of the catalyst is 20% by weight.

Example 2 (according to the invention): hydrodesulfurization with catalyst A
The gasoline, the characteristics of which are described in Table 1, is subjected to hydrotreatment using catalyst A. This test is carried out in an isothermal tubular reactor.

 The catalyst (100 ml) is placed in the desulphurization reactor. The catatyser is first sulfurized by treatment for 4 hours under a pressure of 3.4 MPa at 350 ° C., in contact with a charge containing 4% sulfur in the form of dimethyl disulphide in n-heptane. The hydrodesulfurization is then carried out at a temperature of 340 ° C., with a feed rate of 200 ml / hour. The H2 / charge ratio expressed in liters of hydrogen per liter of charge is 400, the operating pressure is 2.8 MPa.

 Under these conditions, the analysis of the liquid effluent leads to the results presented in Table 2.

 Table 2: Hydrodesulfurization of the feed of table 1 on catalyst A.

Effluent charge
Density 0.73 0.74
Initial point (OC) 26 26
End point (C) 184 184
olefin content (% by weight) 37.7 34.1
IBr (gBr / 100g) 53 48
S total (ppm) 1000 250
S ex mercaptans (ppm) 3 31
RON 89.8 89.0
MON 79.2 79.0
(RON + MON) / 2 84.5 84
Example 3 (comparative): hydrodesulfurization with a cobaltmolybdenum catalyst
The gasoline, the characteristics of which are described in Table 1, is subjected to a hydrotreatment step using a

 The hydrodesulfurization temperature is 240 ° C., the feed rate is 400 ml / hour, the volume of catalyst is 100 ml. The H2 / charge ratio expressed in liters of hydrogen per liter of charge is 400, the operating pressure is 2.8 MPa.

 Under these conditions, the analysis of the liquid effluent leads to the results presented in Table 3.

Table 3: Hydrodesulfurization of the feed of table 1 on a
cobalt-molybdenum catalyst.

Effluent charge
Density 0.73 0.74
Initial point (OC) 26 26
End point (C) 184 184
olefin content (weight%) 37.7 24.7
IBr (gBr / 100g) 53 34
S total (ppm) 1000 250
S ex mercaptans (ppm) 3,130
RON 89.8 86.2
MON 79.2 77.1 (RON + MON) 12 84.5 81.7
Example 4 (according to the invention): hydrodesulfurization with catalyst A and recycling of hydrogen.

 The gasoline, the characteristics of which are described in Table 1, is subjected to a hydrotreatment reaction using catalyst A. This test is carried out in an isothermal tubular reactor. The catalyst (100 ml) is placed in the desulphurization reactor.

The catalyst is first sulfurized by treatment for 4 hours under a pressure of 3.4 MPa at 350 C, in contact with a charge consisting of 4b / o of sulfur in the form of dimethytdisu! is in n-heptane.

 This test is conducted in an insulated tubular reactor under the conditions of Example 2 except that the hydrogen not consumed during the hydrotreatment operation is recycled to the reactor head. This recycling takes place with entrainment of H2S produced by the reaction. The temperature is 340 C, the charge rate is 200 ml / hour. The H2 / total charge ratio expressed in liters of hydrogen per liter of charge is 400, the operating pressure is 2.8 MPa.

 Under these conditions, the analysis of the liquid effluent leads to the results presented in Table 4.

Table 4: Hydrodesulfurization of the feed of table 1 on the
catalyst A with recycling of H2S.

Effluent charge
Density 0.73 0.74
Initial point (C) 26 26
End point (OC) 184 184
olefin content (% by weight) 37.7 34.1
IBr (gBr / 100g) 53 43
S total (ppm) 1000 250
S ex mercaptans (ppm) 3 40
RON 89.8 85.2
MON 79.2 76.9
(RON + MON) / 2 84.5 80.7
Example 5 (comparative): hydrodesulfurization with a cobaltmolybdenum catalyst and recycling of hydrogen.

The gasoline, the characteristics of which are described in Table 1, is subjected to hydrotreatment using a conventional hydrotreatment catalyst based on cobalt and molybdenum sold by the company Procatalyse. This test is carried out in an insulated tubular reactor under the conditions of Example 2 except that the hydrogen not consumed during the hydrodesulfurization operation is recycled to the head
reactor. This recycling is done with H2S training. The catalyst (100m1) is
placed in the desulfurization reactor. The catalyst is first sulfurized by treatment
for 4 hours under a pressure of 3.4 MPa at 350 C, in contact with a charge consisting of 4% sulfur in the form of dimethylidisulfide in n-heptane.

The hydrotreatment temperature is 270 C, the charge rate is 400
ml / hour, the volume of catalyst is 100 ml. The H2 / charge ratio expressed in liters
of hydrogen per liter of charge is 400, the operating pressure is 2.8 MPa.

 Under these conditions, the analysis of the liquid effluent leads to the results presented in Table 5.

Table 5: Hydrodesulfurization of the feed of table 1 on
the cobalt-molybdenum catalyst with recycling of H2S.

Effluent charge
Density 0.73 0.74
Initial point (OC) 26 26
End point (C) 184 184
olefin content (% by weight) 37.7 12.2
IBr (gBr / 100g) 53 16
S total (ppm) 1000 250
S ex mercaptans (ppm) 3,130
RON 89, 8 80.1
MON 79.2 74.9
(RON + MON) / 2 84.5 77.5
With or without recycling of H2S, catalyst A therefore has an efficiency at least equal, or even greater, in desulfurization compared to a cobaltmolybdenum catalyst, and makes it possible to desulfurize the feed without significant reduction in the olefin content and the octane numbers. search and / or engine (RON and MON).

Claims (11)

 sulfide.  about 1 and about 80% by weight, and in which the nickel is at least partly  CLAIMS 1. Hydrodesulfurization catalyst comprising nickel with a content between 2. Catalyst according to claim 1 in which the nickel is supported. 3. Catalyst according to one of the preceding claims, in which the content of  sulfur is between about 0.5 and about 25% by weight. 4. Catalyst according to one of the preceding claims, in which the content of  nickel is between 10 and 50% by weight, and the support has a surface  specific between 80 and 250 m2 / g. 5. Preparation of the catalyst according to one of the preceding claims, in which the  nickel is sulphurized by at least one sulfur compound contained in a solvent. 6. Preparation according to claim 5, in which the sulfur compound is chosen  in the group consisting of alkyl sulfides or organic aryls, sulfides  arylaryl or organic arylalkyl, thiols, thiodiazoles, thioacids  organic, thioramides, thioesters, thiophenols, mercapto-alcohols and  monothioglycols. 7. Preparation according to one of claims 5 or 6, in which the solvent is chosen  in the group formed by essences, alcohols, aldehydes, ketones,  ethers, alcohols, polyalcohols, acids, polyacids, water and glycols. 8. Use of the catalyst according to one of claims 1 to 4 to or prepared according to  one of claims 5 to 7, in a process for hydrodesulfurization of a feed  hydrocarbon. 9. Use according to claim 8 in which the hydrocarbon feedstock is a  essence. 10. Use according to claim 8 in which the hydrocarbon feedstock is a  gasoline from a catalytic cracking unit. 11. Use according to one of claims 8 to 10 wherein the hydrodesulfurization  is carried out at a temperature between about 160 C and 420 C, under a  low pressure between about 0.5 and about 8 MPa, the space velocity of the  liquid is between about 0.5 and about 10 h -1, H2 / HC ratio is  between about 100 and about 600 liters per liter.