GAS PHASE SULFIDATION OF HYDROTREATING AND HYDROCRACKING CATALYSTS

TECHNICAL FIELD

A method for in-situ sulfidation of a hydroconversion catalyst, is provided, in which inactive hydroconversion catalyst is combined with a liquid hydrocarbon prior to sulfidation. Methods for hydroconversion of a liquid hydrocarbon feedstock are also provided, which include such in-situ sulfidation

BACKGROUND

Hydroconversion catalysts are used for hydrodesulfurization, hydrodenitrogenation, hydrodemetallization, hydrocracking, dewaxing, and hydrogenation reactions on industrial scale. Hydroconversion catalysts are typically manufactured and transported with the catalytically-active metal in its oxidised state, and require activation before use, typically via sulfidation process (pre-sulfidation).

It is known in the field to carry out this sulfidation in-situ in the presence of a liquid or gaseous stream comprising sulfide as well as ex-situ, typically by saturating the catalyst with sulfur under controlled production settings. Ex-situ presulfidation does however, require that the catalyst is transported in sealed containers to the site of use.

In WO 00/051729 sulfidation is carried out by contacting the catalyst with a liquid and a H2S rich gas at the same time.

US 2002/000394 propose a method where the catalyst contains an amount of sulfur in the form of a solid or liquid organic sulfur, such as a mercapto compound. This combined composition is then - preferably ex-situ, but possibly in-situ, further sulfided in a procedure first contacting the catalyst with a liquid, and subsequently with a sulfide containing gas.

GB1584785 A, WO 2012/004244 and WO 2017/034943 disclose sulfidation of finely divided and dispersed catalyst for the purpose of of slurry hydroprocessing.

US 6,559,092 disclose a process where a catalyst is contacted with an organic liquid, which is either leached from the catalyst or pyrolyzed, in both cases leaving a substantially dry catalyst pores with a minor residue of carbon or hydrocarbon, which is reported to aid the catalytic performance. WO2019023345 describes a method for treating and sulfiding hydroconversion catalysts, in which a solid hydrocarbon material (i.e. a wax) is combined with inactive catalyst, which is then activated by sulfiding . This method requires the use of additional materials (i.e. wax), extra process steps, additional waste products that may contaminate products, and additional feeds for the hydroconversion reactor. In certain applications, more than one type of catalyst will be loaded and the catalysts will typically be stacked on top of each other. An ex-situ procedure (wax-treatment) will require that each catalyst is wax treated separately.

A simplified method for sulfidation of a hydroconversion catalyst is required, which avoids one or more problems associated with known techniques. Ideally, the method should use product streams which are already present in the hydroconversion plant.

SUMMARY

A method for in-situ sulfidation of a hydroconversion catalyst in a fixed bed reactor is thus provided, said method comprising the steps of: a . combining at least one inactive hydroconversion catalyst, comprising less than 0.1% S, with a liquid hydrocarbon; b. contacting the mixture of inactive hydroconversion catalyst and liquid hydrocarbon with a gaseous stream comprising hydrogen and a sulfur- containing compound, under sulfidation conditions to obtain sulfided hydroconversion catalyst(s), without adding fluids which are liquid under the conditions in the fixed bed reactor in this step; wherein step a and step b are performed in-situ in a hydroconversion unit.

In a further aspect, a method for hydroconversion of a liquid hydrocarbon feedstock is provided, said method comprising the step of: introducing a liquid hydrocarbon feedstock to a hydroconversion unit and performing hydroconversion of a liquid hydrocarbon feedstock by means of said sulfided hydroconversion catalyst under hydroconversion conditions; wherein said hydroconversion catalyst has been sulfided by the method described herein in which step a and step b thereof are performed in-situ in said hydroconversion unit. In a further aspect, a method for hydroconversion of a liquid hydrocarbon feedstock is provided, said method comprising the steps of: i. providing a fixed bed hydroconversion unit containing at least one inactive

hydroconversion catalyst containing less than 0.1% S;

ii. introducing a predetermined volume of liquid hydrocarbon to said hydroconversion unit such that inactive hydroconversion catalyst(s) is combined with liquid

hydrocarbon;

iii. contacting the mixture of hydroconversion catalyst(s) and liquid hydrocarbon with a gaseous stream comprising hydrogen and a sulfur-containing compound under sulfidation conditions to obtain sulfided hydroconversion catalyst , without adding fluids which are liquid under the conditions in the fixed bed hydroconversion unit in this step;

iv. introducing a flow of said liquid hydrocarbon feedstock to said hydroconversion unit and performing hydroconversion of said flow of liquid hydrocarbon feedstock by means of said sulfided hydroconversion catalyst under hydroconversion conditions.

Further details of the methods are provided in the dependent claims and the following description text.

In a further embodiment of the method for in-situ sulfidation the steps a and b (or the steps i and ii) are performed sequentially, without any intervening steps, with the associated benefit of providing a simple process, providing effective sulfidation.

In a further embodiment of the method for in-situ sulfidation the liquid hydrocarbon has a pour point determined by ASTM D5949 of 55°C or below, such as 50°C or below, with the associated benefit of such liquid hydrocarbons being readily available and easy to handle.

In a further embodiment of the method for in-situ sulfidation the liquid hydrocarbon is selected from middle distillates, kerosene, naphtha, vacuum gas oil (VGO), and heavy gas oil, with the associated benefit of such liquid hydrocarbons being readily available at the site of the hydroconversion unit.

In a further embodiment of the method for in-situ sulfidation the step of combining inactive hydroconversion catalyst with a liquid hydrocarbon takes place in a temperature range of between 20°C - 250°C, preferably between 50°C - 120°C, within which range the

hydrocarbon concerned is in the liquid state, with the associated benefit of the temperature range being efficient for the hydrocarbon penetrating the pores of the inactive

hydroconversion catalyst. In a further embodiment of the method for in-situ sulfidation the sulfidation conditions comprise a temperature between 100°C to 600 °C, preferably 120°C to 450°C, with the associated benefit of the temperature range being efficient for sulfiding the hydroconversion catalyst.

In a further embodiment of the method for in-situ sulfidation the sulfur-containing compound is hydrogen sulfide (H ₂ S) or a compound which decomposes into H2S such as mercaptans, thiophenes, dimethyl sulphide (DMS), di-methyl-di-sulfide (DMDS), di-methyl-sulphoxide (DMSO), di-t-butyl-polysulfide (DBPS), and suitable S-containing refinery outlet gasses; preferably H ₂ S or DMDS, or mixtures thereof, with the associated benefit of these compounds being well tested for sulfidation, cost effective and readily available. All these sulfur- containing compounds are gaseous or decompose to gaseous products under the conditions in the hydroconversion reactor.

In a further embodiment of the method for in-situ sulfidation the gaseous stream comprises 0.5 % to 10 % by volume of hydrogen sulfide, with the associated benefit of this

concentration being well tested for sulfidation.

In a further embodiment of the method for in-situ sulfidation the hydroconversion catalyst comprises at least one catalytically active transition metal or oxide thereof, with the associated benefit of such catalysts being well suited for the described sulfidation procedure.

In a further embodiment of the method for in-situ sulfidation said catalytically active transition metal is selected from Mo, W, Co or Ni, or combinations thereof, suitably NiMo, CoMo or NiCoMo, with the associated benefit of such catalysts being well suited for the described sulfidation procedure.

In a further embodiment of the method for in-situ sulfidation the catalytically active transition metal is supported on a metal oxide support, preferably zeolite, alumina (Al ₂ 0 ₃ ), titania (Ti0 ₂ ), silica (Si0 ₂ ), silica-alumina (Si0 ₂ -Al ₂ 0 ₃ ) or combinations thereof, with the associated benefit of such supports providing a catalyst being well suited for the described sulfidation procedure and use in hydroconversion.

In a further embodiment of the method for in-situ sulfidation at least two different inactive hydroconversion catalysts are combined with a liquid hydrocarbon in step a, with the associated benefit of a process with two hydroconversion catalyst being especially well suited for in-situ sulfidation. In a further embodiment of the method for hydroconversion the liquid hydrocarbon used for sulfidation in step a is a portion of said liquid hydrocarbon feedstock hydrocon verted in said hydroconversion unit, with the associated benefit of this feedstock being especially available.

In a further embodiment of the method for hydroconversion all steps i. - iv. are performed sequentially, without any intervening steps, with the associated benefit of providing a simple process, providing effective sulfidation.

In a further embodiment of the method for hydroconversion the liquid hydrocarbon has a pour point determined by ASTM D5949 of 50°C or below, preferably 45°C or below, with the associated benefit of such liquid hydrocarbons being readily available and easy to handle.

In a further embodiment of the method for hydroconversion the step of combining inactive hydroconversion catalyst with a liquid hydrocarbon takes place in a temperature range of between 20°C - 250°C, preferably between 50°C - 120°C, within which range the hydrocarbon concerned is in the liquid state, with the associated benefit of the temperature range being efficient for the hydrocarbon penetrating the pores of the inactive

hydroconversion catalyst.

In a further embodiment of the method for hydroconversion the liquid hydrocarbon and/or the liquid hydrocarbon feedstock are selected from middle distillates, kerosene, naphtha, vacuum gas oil (VGO), and heavy gas oil, with the associated benefit of such liquid hydrocarbons being readily available at the site of the hydroconversion unit.

In a further embodiment of the method for hydroconversion the sulfidation conditions comprise a temperature between 100°C to 600 °C, preferably 120°C to 450°C, with the associated benefit of the temperature range being efficient for sulfiding the hydroconversion catalyst.

In a further embodiment of the method for hydroconversion the sulfur-containing compound is hydrogen sulfide (H ₂ S) or a compound which decompose into H2S such as mercaptans, thiophenes, dimethyl sulphide (DMS), di-methyl-di-sulfide (DMDS), di-methyl-sulphoxide (DMSO), di-t-butyl-polysulfide (DBPS), and suitable S-containing refinery outlet gasses, preferably H ₂ S or DMDS, or mixtures thereof, with the associated benefit of these compounds being well tested for sulfidation, cost effective and readily available.

In a further embodiment of the method for hydroconversion the gaseous stream comprises 0.5 % to 10 % by volume of hydrogen sulfide, with the associated benefit of this

concentration being well tested for sulfidation. In a further embodiment of the method for hydroconversion the hydroconversion catalyst comprises at least one catalytically active transition metal or oxide thereof, with the associated benefit of such catalysts being well suited for the described sulfidation procedure.

In a further embodiment of the method for hydroconversion said catalytically active transition metal is selected from Mo, W, Co or Ni, or combinations thereof, preferably NiMo, CoMo or NiCoMo, with the associated benefit of such catalysts being well suited for the described sulfidation procedure.

In a further embodiment of the method for hydroconversion the catalytically active transition metal is supported on a metal oxide support, preferably zeolite, alumina (Al ₂ 0 ₃ ), titania (Ti0 ₂ ), silica (Si0 ₂ ), silica-alumina (Si0 ₂ -Al ₂ 0 ₃ ) or combinations thereof, with the associated benefit of such supports providing a catalyst being well suited for the described sulfidation procedure and use in hydroconversion.

In a further embodiment of the method for hydroconversion the hydroconversion unit in step i. contains at least two inactive hydroconversion catalysts, with the associated benefit of a process with two hydroconversion catalyst being especially well suited for in-situ sulfidation.

DETAILED DISCLOSURE

The term "liquid", when used to refer to the "liquid" hydrocarbon refers to a material in the liquid state under the conditions of temperature and pressure used in the methods of the present invention. For instance, combining inactive hydroconversion catalyst with a liquid hydrocarbon usually takes place in a temperature range of between 20°C - 250°C, preferably between 50°C - 120°C, within which range the hydrocarbon concerned is in the liquid state.

This step also usually takes place in a pressure range of between 5 bar - 300 bar, preferably between 20 bar - 200 bar, within which range the hydrocarbon concerned is in the liquid state.

The term "in-situ" - when applied to the method steps of the invention - means that both steps are performed in the same unit, without removal of the catalyst or the liquid hydrocarbon material from the unit between the steps of the method.

The term "inactive" when applied to the hydroconversion catalyst typically means

hydroconversion catalyst which is in its oxidised state. A hydroconversion catalyst can be supplied in inactive form from a manufacturer, or can be inactive when recycled from previously-active hydroconversion catalyst in its oxidised state. An aspect of the present disclosure may involve hydroconversion catalysts comprising low amounts of sulfur, especially sulfur in reduced state, such as below 0.5 wt% or even below 0.1 wt%.

In a first aspect, therefore, a method for in-situ sulfidation of a hydroconversion catalyst is provided. The method comprises the steps of: a. combining at least one inactive hydroconversion catalyst with a liquid

hydrocarbon; b. contacting the mixture of inactive hydroconversion catalyst(s) and liquid hydrocarbon with a gaseous stream comprising hydrogen and a sulfur- containing compound under sulfidation conditions to obtain sulfided hydroconversion catalyst(s);

Notably, step a and step b of this method are performed in-situ in an industrial

hydroconversion unit; i.e. the same hydroconversion unit. Suitably, step a and step b of this method are performed sequentially, without any intervening steps.

Hydroconversion catalyst

The hydroconversion catalyst comprises at least one, preferably two and possibly three, catalytically active transition metals. The catalytically active transition metal is suitably selected from Mo, W, Co or Ni, or combinations thereof, particularly NiMo, CoMo or NiCoMo. Prior to sulfidation, the transition metal is in its oxide form.

The catalytically active transition metal is supported on a ceramic support, typically a metal oxide support, preferably zeolite, alumina (Al ₂ 0 ₃ ), titania (Ti0 ₂ ), silica (Si0 ₂ ), silica-alumina (Si0 ₂ -Al ₂ 0 ₃ ) or combinations thereof. The loading of the transition metal on the support is typically between 0.1 - 50 wt% calculated as oxides on the dry weight of the catalyst, preferably between 15 - 45 wt% calculated as oxides on the dry weight of the catalyst.

Additional materials which may be included in the hydroconversion catalyst include Group I metals (e.g. Rb, Cs, Na, K) and/or Group II metals (e.g. Mg, Ca, Ba). Other materials which may be included in the hydroconversion catalyst include a source of non-metal, e.g. a source of phosphorous or a source of boron. A particularly interesting hydroconversion catalyst comprises molybdenum and nickel as catalytically active transition metal, deposited on an alumina (e.g. gamma-alumina) support.

In one aspect of the invention, at least two different inactive hydroconversion catalysts are combined with a liquid hydrocarbon in step a. The catalysts may be "different" in terms of the transition metal, the concentration of said metal(s), the ceramic support and/or the additional materials. They may also be "different" in their physical structure; e.g. the form, porosity or dimensions of the catalyst particles.

The present technology - using liquid hydrocarbon - is ideally suited for sulfidation of two or more different inactive hydroconversion catalysts, as the liquid hydrocarbon can contact all types of hydroconversion catalyst in situ. With a wax treament, each catalyst would have to be contacted separately.

In this instance, more than one type of catalyst is present in the hydroconversion unit. When at least two different inactive hydroconversion catalysts are present, they are typically present in separate layers in the hydroconversion unit. Alternatively, the two different inactive hydroconversion catalysts in the hydroconversion unit may be mixed prior to loading in the unit.

Liquid hydrocarbon

In the first step of the above-described method, combining inactive hydroconversion catalyst is combined with a liquid hydrocarbon. "Combining" involves feeding liquid hydrocarbon into a tubular reactor containing catalyst. Combining inactive hydroconversion catalyst with a liquid hydrocarbon suitably takes place in a temperature range of between 20°C - 250°C, preferably between 50°C - 120°C, within which range the hydrocarbon concerned is in the liquid state.

The liquid hydrocarbon has a pour point determined by ASTM D5949 of 55°C or below, such as 50°C or below, preferably 45°C or below. The liquid hydrocarbon is typically selected from middle distillates, kerosene, naphtha, vacuum gas oil (VGO), and heavy gas oil. In many applications the same oil as that being processed in the unit will be used for the sulfidation.

The hydroconversion unit is as a starting point "dry". After loading of catalyst the liquid hydrocarbon is added together with a small stream of hydrogen (which normally will be recycled). Normally more liquid is added than needed for filling the pore volume of the catalyst. Any excess liquid will be taken out downstream the hydroconversion unit in the separation system. Recycling of the oil is a possibility. When the catalyst has been wetted with liquid hydrocarbon the addition of liquid is stopped. The addition of hydrogen continues and addition of a S-containing compound starts when the temperature of the stream entering the reactor is so high that decomposition of the S-containing compound can take place. The gas is normally recycled all the time.

The amount of liquid hydrocarbon used generally is about 50-500% of the catalyst pore volume which can be filled with the liquid at issue under the conditions of application of the liquid. The pore volume of the catalyst can easily be determined by slowly adding liquid under said conditions to a certain amount of catalyst in a closed flask while shaking and determining by visual inspection when the liquid is no longer adsorbed. The way in which the catalyst is contacted with liquid hydrocarbon is not critical to the invention as long as it is ensured that each catalyst particle is contacted with the liquid. To get the desired effect an amount of about 100-300% of the catalyst pore volume, is preferred.

Sulfidation conditions

Sulfided hydroconversion catalyst is obtained by contacting the mixture of hydroconversion catalyst and liquid hydrocarbon with a gaseous stream comprising hydrogen and a sulfur- containing compound under sulfidation conditions. The sulfur-containing compound is suitably hydrogen sulphide and/or a compound which is decomposable into hydrogen sulphide under the conditions prevailing during the contacting of the catalyst with hydrogen and sulfur- containing compounds.

The gaseous stream typically comprises 0.5 % to 10 % by volume - such as 2 to 5% by volume - of sulfur-containing compound, e.g. hydrogen sulfide. The remainder of the gaseous stream would typically be hydrogen.

Sulfidation conditions suitably comprise a temperature between 100°C to 600 °C, preferably 120°C to 450°C.

The sulfur-containing compound is suitably hydrogen sulfide (H ₂ S) and/or suitable components decomposable into H ₂ S such as mercaptans, thiophenes, dimethyl sulphide (DMS), di-methyl-di-sulfide (DMDS), di-methyl-sulphoxide (DMSO), di-t-butyl-polysulfide (DBPS, which is present in the commercial product SulfrZol54 from Lubrizol) and suitable S- containing refinery outlet gasses. Of these, H ₂ S or DMDS are preferred. Mixtures of such compounds are also conceivable. The skilled person knows how to select a sulfur compound which will decompose under the conditions applied The contacting in the gaseous phase with hydrogen and a sulfur-containing compound can be done in one step. In this case, it is preferably carried out at a temperature of between 100°C to 600 °C, preferably 120°C to 450°C.

The contacting in the gaseous phase with hydrogen and a sulfur-containing compound may also be carried out in two steps, with the first step being performed at a lower temperature of about 120-250°C, preferably about 120-225°C. The second step is generally carried out at a temperature of about 150-450°C, preferable about 150-400°C, more preferably about 150- 370°C. If so desired, this process may also be carried out in more than two steps, e.g., in three steps or in a continuous mode, as long as the first step, or the start of the process, is carried out at a lower temperature than a further step, or later part of the process.

Further aspects

In a second aspect, a method for hydroconversion of a liquid hydrocarbon feedstock is provided. The method comprising the step of: introducing a liquid hydrocarbon feedstock to a hydroconversion unit and performing hydroconversion of a liquid hydrocarbon feedstock by means of said sulfided hydroconversion catalysts under hydroconversion conditions; wherein said hydroconversion catalyst has been sulfided by the method according to the first aspect, in which step a and step b thereof are performed in-situ in said hydroconversion unit.

Suitably, the liquid hydrocarbon used in step a. is a portion of said liquid hydrocarbon feedstock hydroconverted in said hydroconversion unit. However, in some cases the liquid hydrocarbon used in catalyst sulfidation may be different from the liquid hydrocarbon feedstock to be hydroprocessed . For instance, diesel has a lower pour point than VGO and may be easier to introduce when the unit is heating up. After the unit is heated up it is easier to process a more heavy feedstock.

Inactive hydroconversion catalyst(s) are combined with a predetermined amount of liquid hydrocarbon, as per step a. of the method of the first aspect. The mixture of hydroconversion catalyst and liquid hydrocarbon is contacted with a gaseous stream comprising hydrogen and a sulfur-containing compound under sulfidation conditions to obtain sulfided hydroconversion catalyst, as per step b. of the method of the first aspect.

After sulfidation of the catalyst, the same or different liquid hydrocarbon is used as feedstock in a hydroconversion step under hydroconversion conditions, as was used to activate the hydroconversion catalyst. This method allows in-situ sulfidation and subsequent

hydroconversion, in the hydroconversion unit without intervening steps. Furthermore, the sulfidation can be carried out with hydrocarbon liquids which are readily available on-site, thus avoiding the need for additional treatment steps or additional feedstocks.

The hydroconversion unit is a reactor vessel, or collection of reactor vessels, having at least one inlet for liquid hydrocarbon/liquid hydrocarbon feedstock and at least one outlet for hydroconverted product. Hydroconversion catalyst is placed in the hydroconversion unit, and arranged such that flows of hydrocarbon liquid are converted over the catalyst in the presence of hydrogen.

In a third aspect, a method for hydroconversion of a liquid hydrocarbon feedstock is provided, said method comprising the steps of: i. providing a hydroconversion unit containing at least one inactive hydroconversion catalyst(s) ; ii. introducing a predetermined volume of liquid hydrocarbon to said hydroconversion unit such that inactive hydroconversion catalyst(s) is combined with liquid hydrocarbon; iii. contacting the mixture of hydroconversion catalyst(s) and liquid hydrocarbon with a gaseous stream comprising hydrogen and a sulfur-containing compound under sulfidation conditions to obtain sulfided hydroconversion catalyst; iv. introducing a flow of said liquid hydrocarbon feedstock to said hydroconversion unit and performing hydroconversion of said flow of liquid hydrocarbon feedstock by means of said sulfided hydroconversion catalyst under hydroconversion conditions.

The main products of hydroconversion of the liquid hydrocarbon feedstock are typically hydrotreated products ranging from light and heavy naphtha, kerosene, diesel and VGO. The hydrotreated products may be further processed over a hydrocracking catalyst and/or dewaxing catalyst and/or hydrogen catalyst (see Background section above)

In one aspect, the liquid hydrocarbon introduced to said hydroconversion unit in step ii . is a portion of said liquid hydrocarbon feedstock hydroconverted in said hydroconversion unit in step iv. Suitably, the hydroconversion unit in step i. contains at least two inactive hydroconversion catalysts. Optionally the hydroconversion unit in step i. contains one inactive hydroconversion catalyst and one active (i.e. pre-sulfided) hydroconversion catalyst.

All details of the method of the first aspect described above (hydroconversion catalyst, hydrocarbon feedstock etc.) are also relevant for the methods of the second and third aspects, mutatis mutandis.

EXAMPLES

Table 1. Feedstock properties

Type of feed VGO (vacuum gas oil)

Nitrogen (ASTM D-4629), ppmwt 1633

Sulfur (ASTM D-4294), wt % 2.1

SG (ASTM D-4052) 0.934

Pour Point (D-5949),°C 42

Simulated Distillation, °C (ASTM D-7213C)

IBP 284

5 % 363

10 % 387

30 % 430

50 % 462

70 % 499

90 % 548

95 % 568

FBP 604

Comparative Example 1

80 ml of a commercially available hydrotreating catalyst from Topsoe named TK- 611 HyBRIM™ containing about 24 % by weight of molybdenum, calculated as tri-oxide, and about 4 % by weight of nickel, calculated as oxide, deposited on a gamma-alumina support was loaded in a reactor tube. The catalyst was tested in a pilot plant unit having one reactor furnace with the reactor tube followed by a high pressure separator and a low pressure separator with nitrogen stripping . Prior to testing the catalyst was sulfided at 70 barg in the pilot plant unit using the following procedure: 1) The reactor temperature was raised from room temperature to 200°C in a hydrogen flow of 70 Nl/h using a heat ramp of 30°C/h; 2) addition of DMDS (di-methyl-di- sulfide) at a rate of 2.8 ml/h was started when the reactor temperature was 190°C; 3) when the reactor temperature reached 200°C the reactor temperature was raised to 225°C using a heat ramp of 15°C/h; 4) about 90 minutes after the temperature reached 225°C a gas sample was taken downstream the reactor for measurement of the hydrogen sulfide content by a Draeger tube; 5) additional gas samples were taken every half hour until the content of hydrogen sulfide in the gas samples was found to be higher than 3000 vol ppm; 6) when the hydrogen sulfide in the gas samples was found to be higher than 3000 vol ppm the reactor temperature was raised from 225°C to 330°C using a heat ramp of 20°C/h; 7) when the reactor temperature reached 330°C the temperature was kept at this temperature for 4 hours; 8) the DMDS addition was then reduced to 0.14 ml/h and the reactor temperature was reduced from 330°C to 200°C using a cooling ramp of about 25°C/h. After completion of the sulfiding the addition of DMDS was stopped and the reactor pressure was raised to 140 barg before the VGO (vacuum gas oil) with the properties given in Table 1 was fed to the reactor at a rate of 92 ml/h. The test conditions are given in Table 2.

Table 2. Test conditions

Reactor temperature, °C _ 370

Pressure, barg _ 140

LHSV, h ¹ _ 1.15

Hz/oil, Nl/I_ 765

The oil product from the reactor was analyzed for sulfur and nitrogen. The average sulfur and nitrogen content of the product oil from run hour 250 to run hour 300 after completion of the sulfiding are given in Table 3.

Example 2 - method of the present invention

The catalyst used in the comparative example 1 was loaded in the test reactor as described in example 1. Prior to the sulfiding the catalyst was treated with the VGO given in Table 1 as follows. The reactor pressure was raised to 70 barg by adding 15 Nl/h hydrogen to the reactor and at the same time the reactor temperature was set to 60°C. Then the VGO was fed to the reactor at an average rate of 100 ml/h for about 4 hours in order to fill the pores of the catalyst with VGO. After filling of the catalyst with VGO the same sulfiding procedure as that used in example 1 was applied.

After filling of the catalyst with VGO the feeding of VGO is stopped. Then the procedures 1) to 8) from example 1 are carried out for sulfidation of the catalyst. After completion of the sulfidation the VGO from example 1 is processed in the same way as described in example 1 After completion of the sulfiding the catalyst was tested in the same way as in example 1. The oil product from the reactor was analyzed for sulfur and nitrogen. The average sulfur and nitrogen content of the product oil from run hour 250 to run hour 300 after completion of the sulfiding are given in Table 3. Table 3. Test results

Example 1 2

Product nitrogen (ASTM D-4629), ppmwt 147 101

Product sulfur (ASTM D-7039), ppmwt 792 526

The results given in Table 3 show that the product from the wetted catalyst according to the invention has a significant lower nitrogen and sulfur content as compared with the product from the comparative method, indicated a catalyst with higher activity, due to a more efficient sulfidation process.

Although the invention has been described with reference to a number of aspects, examples and embodiments, these aspects, examples and embodiments may be combined by the person skilled in the art, while remaining within the scope of the present invention.