EP0298111A1

EP0298111A1 - Sulfuration of hydrorefining catalysts

Info

Publication number: EP0298111A1
Application number: EP88901271A
Authority: EP
Inventors: Claude Gueguen; Patrice Guesnet; Henri Jacquez; Gérard Savin
Original assignee: Societe National Elf Aquitaine; Societe Nationale Elf Aquitaine Production SA; Elf France SA
Current assignee: Societe National Elf Aquitaine; Elf Antar France; Societe Nationale Elf Aquitaine Production SA
Priority date: 1987-01-20
Filing date: 1988-01-19
Publication date: 1989-01-11
Also published as: WO1988005338A1; FR2609650A1; JPH01502094A; FR2609650B1

Abstract

Procédé de sulfuration de catalyseurs d'hydroraffinage caractérisé en ce que l'agent sulfurant est au moins un polysulfure organique de formule générale R - Sn - R', où R et R' identiques ou différents représentent un radical alkyle linéaire ou ramifié saturé ou insaturé en C1 à C4 et n est compris entre 3 et 10. Ce procédé permet une sulfuration efficace à des températures peu élevées.Process for the sulfurization of hydrorefining catalysts characterized in that the sulfurizing agent is at least one organic polysulfide of general formula R - Sn - R', where R and R' identical or different represent a saturated or unsaturated linear or branched alkyl radical in C1 to C4 and n is between 3 and 10. This process allows efficient sulfurization at low temperatures.

Description

SULFURIZATION OF HYDROREFINING CATALYSTS

This invention relates to a sulfura process for hydrorefining catalysts.

We use the term hydrorefining to denote refining operations consisting in tra 5 a hydrocarbon feed at high temperature and under hydrogen pressure in the presence of a suitable catalyst.

Among the hydrorefining operations

Hydrotreating allows to rid the hydrocarbon ch of part of its content in so

I Q organic, organic nitrogen, oxygen and sometimes metals.

The hydrocracking units also make it possible to partially hydrogenate certain unsaturated molecules to reduce the average molecular weight of the charge 5 by breaking carbon-carbon bonds.

These hydrorefining operations are carried out with catalysts composed of metallic sulphides deposited on a porous support.

The porous supports are generally chosen for aluminum and / or silicon oxides. The commonly used support is gamma alumina.

Among the metal sulfides, the sulfides of the metals of groups VI B and of the periodic table of the elements, such as molybdenum, tungsten, nickel and cobalt, are preferably chosen.

The sulphides of these metals are unstable and decompose in the presence of air. The metals are introduced into the catalyst in the form of their oxides and are transformed into sulphides in the reactor. 0 This operation, called sulfurization or pre-sulfurization, must be repeated each time the catalyst is regenerated.

For the sulfurization of the catalyst, it is possible to use hydrogen sulphide, the sulfur compounds present in the hydrocarbon feed treated on the catalyst or else sulfur-containing additives. Among the sulfur additives, the p1 dimethyldisulphide (DMDS) is commonly used. However, sulfurization by DMDS requires relatively high temperatures and takes place in several stages of increasing temperatures.

Thus a sulfurization by DMDS at 220-280 ° C proves insufficient to obtain sufficiently active catalysts, a good degree of sulfurization is obtained only in a second stage of sulfurization at a temperature

10 around 300-360 ° C.

Sulphurization by DMDS also leads to fairly large deposition of coke. These co deposits contribute greatly to the aging and deactivation of the catalyst. -, c We have now found a sulfurization process for catalysts, which allows efficient and homogeneous sulfurization at lower temperatures with a reduced coke content.

Our process - of sulfurization of a catalyst

20 containing at least one active metal in the form of oxide deposited on a porous support, by simultaneous passage of hydrogen from a hydrocarbon charge containing a sulfurizing agent e characterized in that the sulfurizing agent is at least organic polysulphide of general formula or R and R ', which are identical or different, represent a linear or branched alkyl radical saturated or unsaturated with C. to C. n is between 3 and 10.

The nature of the active metal varies very widely depending on the hydrorefining operation envisaged. generally uses mixtures of metals from groups VI and VIII of the periodic table. The group VI B metals include molybdenum, tungsten, and the group VIII metals include iron, cobalt and nickel. Sometimes group VIII meta nobles such as rhodium, platinum and palladium are also used. All these metals can be used in melan with metals from the lanthanide group such as lanthanum, cerium or neodymium. The most common catalysts contain d of these metals. Sometimes ternair catalysts containing three metals are used, such as, for example, iron-cobalt-molybdenum or nickel-cobalt-molybdenum catalysis.

The metal content of the catalysts is between about 0.1 and 15% by weight.

The metals are deposited on a support por generally chosen from alumina, silica, silica-alumina, zeolites, clays or mixtures.

This sulfurization process can be implemented before any refining operation requiring the presence of a metal catalyst in the form of sulphides. It follows that the hydrocarbon feedstocks are varied ranging from crude oil to ^'petroleum fractions such as gasolines, medium or heavy distillates and thermal or catalytic treatment residues.

The polysulphides used are often mixtures of sulphides of different rank,. Or n represents an average value.

Among the polysulphides, it is possible to choose, for example, diethyltrisulphide, diethyltrisulphide, mixtures of dimethylpolysulphides containing on average four sulfur atoms, mixtures of diethylpolysulphides containing average four sulfur atoms or diterbutylpolysulphides containing on average five sulfur atoms per molecule.

Dimethyltrisulfide is the main dimethyldisulfide or DMDS commercial impurity. It can be prepared by distillation of the latter. Trisulfide is obtained with a purity exceeding 98%.

In the same way the diethyldisulfide prepared oxidation of ethylmercaptan by sulfur contains diethyltrisulfide which is separated by distillation with a purity exceeding 98%.

The polysulphides can be prepared reaction of mercaptans or dialkyldisulphides with solid sulfur in the presence of a basic catalyst such as alkyla ines for example triethylamine. In reality, mixtures of polysulphides are obtained, the average rank of which depends on the quantity of sulfur used.

It may be economically advantageous to use the polysulphides obtained by sulphurization of mixtures of mercaptans from the residues of the MEROX units. In the MEROX units, the mercaptans of the hydrocarbon charges are extracted using alkaline aqueous solutions and the presence of a special catalyst. The residues of the MEROX units are mixtures of symmetrical and asymmetric dialkyl disulfides. Polysulfides containing th

On average three, four, five or more sulfur atoms can be obtained by adding cold sulfur in the presence of a basic catalyst.

The polysulphides used in the process according to the invention may contain a certain percentage, even

15 around 20% of disulfides provided that their average rank is equal to or greater than 3.

The sulfurization of the catalyst according to the invention is generally carried out by simultaneous passage over the hydrogen catalyst and of the hydrocarbon feed containing 0.1

20 10% by weight and preferably 0.5 to 5%, expressed as sulfur of sulfur-containing compounds.

The pressure is generally between 1 and 30 bars and preferably between 15 and 150 bars. The speed

_ ₅ space expressed in m 3 of liquid charge injected per m3 of catalyst and hour (WH) is between 0.1 and 15 e, preferably between 0.5 and 3.

A flow rate of 100 to 3000 1 norma of hydrogen is used per 1 normal of gas.

₃₀ The temperature of the reaction is reached pa bearings. The sulfurization temperature depends on the nature of the catalyst, especially the metal deposited on the porous support. For an identical catalyst, the use of polysulphides according to the invention makes it possible to sulphide at

_ lower temperatures than using DMDS. To obtain complete sulfurization with D, we must proceed in stages, following a first sulphurization stage around 220-280 ° C with a second stage where the temperature reaches 300 to 360 ° C. With polysulphides the first stage the sulfurate reaction starts around 150 ° C and it is practically complete at 250 ° C.

A catalyst sulfurized at 250 ° C by DMDS p contain 4.4% by weight of sulfur. For example, in the case of sulfurization with our polysulphides, the same sulph catalyst at 250 ° C. contains 5.6% sulfur.

By carrying out sulfurization at lower temperatures, in particular at temperatures below 25, the reduction of metal oxides in the presence of hydrogen in reduced species is avoided (0. WEISSER and S. LA in Sulfide catalysts their properties and applicati (Pergamon Press , 1973)). The sulfurization of reduced species is very difficult if not impossible. Thus carrying out the sulfurization at lower temperatures, obtains a better quality catalyst.

Finally, by comparing the level of coke of sulfurized catalyst with DMDS and with our polysulphide we find a rate of coke much lower in our ca As coking constitutes one of the most important phenomena of aging of the catalyst it is very advantageous to limit the formation of coke during sulfurization.

The performances of the sulfurized catalysts with n polysulphides were compared with those of a sulfurized catalysis by the charge or with DMDS, hydrodesulfurization, hydrodesazotation and for the improvement of the density of the charge. The results with isotemperatur are superior when using polysulfides.

The examples below illustrate the invention without, however, limiting it. EXAMPLE 1

PREPARATION OF POLYSULFIDES: Dimethyltrisulfide: (DMTS)

Dimethyltrisulfide is the main impurity of commercial DMDS and was prepared by distillation of the latter. The trisulphide obtained has a purity of 98%. Diethyltrisulfide: (DETS)

The diethyldisulfide prepared by oxidation of ethyl mercaptan by sulfur contains trisulfide which the o separates by distillation. The trisulfide used had a purity of 98%.

Di éth 1té rasulfide: (DMTES)

This mixture was prepared by cold reaction of DMDS or solid sulfur in the presence of a basic catalyst. S gross formula is CH_, S. CH ,. In fact it is a mixture of polysulfides containing more than 80% of polysulfides of rank ^ 3. The same product can be prepared by reaction of raethyl rnercaptan with a large excess of sulfur. Diethyltetrasulfide: (DETES)

This mixture was prepared by cold reaction of diethyldisulfide on solid sulfur in the presence of a basic catalyst. Its raw formula is C_H ₅ S ₄ C_H ₅ . In fact it is a mixture of polysulfides of rank_ containing more than 80% of polysulfides of rank ^ 3. The same product can be prepared by direct reaction of etl yn rnercaptan on sulfur. Ditertiobutylpentasulfide: (DTBPS)

This mixture was prepared by hot oxidation of tert-bututyercaptan with sulfur in the presence of a basic catalyst. This mixture of crude formula ter-C .H ... S, ter-C.H- contains more than 85% of polysulphides ter-C.H., - S ter-C.H ... of rank ^ r 3.

By this method, mixtures of medium ran polysulfides 3 or 4 can also be obtained. MEROX polysulfides:

The residues of MEROX units are mixtures of symmetrical and asymmetric dialkyl disulfide. The MEROX residue tested contained:

70% DMDS

20% Methylethyldisulfide

10% Diethyldisulfide

It was sulfurized by adding cold sulfur in the presence of a basic catalyst.

The mixture obtained contains polysulphides. Its average composition is:

It is in fact a mixture of polysulphides of sulfur rank e greater than 2, 80% of the polysulphides being of rank ^ The same mixture can be obtained directly by reaction, _ of a methyl and ethyl mercaptan mixture on sulfur e determined quantity. EXAMPLE 2

CATALYST SULFURATION The tests were carried out on 2 catalysts

1) CoMo Containing 3.2% Cobalt Oxide and 14.4% Oxide

20 of molybdenum on extruded alumina:

Pore volume 0.48g / cm ³ Density 0.67g / cm ³

Specific surface 210m ² / g

2) NiMo containing, 3% nickel oxide 14% molybdenum oxide and 0.1% Na_0 on extruded alumina.

Pore volume 0.38g / cm ³ Density 0.71g / cm ³

Specific surface 200m ² / g

30 Description of laboratory equipment

- A quartz tube (diameter 8mm) is placed in a tubular tube.

- A pump continuously injects the sulfurization agent inside the quartz tube at the rate of 250 to 400 mg of

_TC sulfur content per hour.

- The quartz tube is continuously swept by a stream of hydrogen with a flow rate of 16 1 / h

- In the center of the quartz tube are placed two grams of CoMo or NiMo catalyst. The catalyst after sulfurization is analyzed (measurement of the sulfur contained by micro analysis)

The hydrogen loaded with sulfurizing agent is continuously analyzed at the outlet of the catalytic bed, by gas chromatography (detector: catharometer) which makes it possible to determine the rate of decomposition of the sulfurizing agent at each instant.

- Each presulphurization test of duration equal to 7 hours is carried out in isotherm (1 single stage of presulphurization).

10 Tests No. l

- Catalyst tested: CoMo

- Sulfurization agents tested: dimethylsulfide (DMS), dimethyldisulfide (DMDS), dimethyltrisulfide (DMTS), diethyltrisulfide <DETS), a medium dimethyltetrasulfide

15 obtained by direct sulphurization of DMDS (DMTES), a medium diethyltetrasulphide obtained by direct sulphurization of DEDS (DETES), a medium diterbutylpentasulphide (DTBPS) obtained by direct sulphurization of terbutyl mercaptan and a sulfurized MEROX pol as described above (MERS 4). They were

20 used separately to sulfurize the CoMo catalyst at various temperatures (150-350 ° C).

- Each catalyst obtained after presulfurization by a presulfurizing agent given at a given temperature has been analyzed.

- _ς - After 5 hours of isothermal presulfurization, the decomposition rate of each presulfurization product was determined at each presulfurization temperature. This level was expressed as "active sulfur level of the presulfurization agent" (S)

30 ^S l S = 100%

S, = H_Ξ content released

S_ = releasable H_S content if all the product, _ς had been decomposed TABLE 1 RATE OF ACTIVE SULFUR (S)

PRESULFURATION TEMPERATURE

AGENT OF

PRESULFU¬: 125 ° C 150 175 200 225 250 300 350

RATION

DMS: 0 0 0 0 0 3 82 96

DMDS 0 0 0 0 16 31 90 100

DMTS: 0 0 2 7 48 75 98 100

DETS 0 1 13 39 72 87 100 100

DMTES 0 2 18 45 85 91 100 100

DEBTS: 0 5 26 57 90 98 100 100

DTBPS: 0 5 25 54 87 96 100 100

MERS 4: 0 1 10 46 85 91 100 100

TABLE 2 PERCENTAGES OF SULFUR FIXED ON THE CATALYST AFTER EACH ISOTHERMAL PRESULFURATION.

PRESULFURATION TEMPERATURE (° C)

AGENT OF

PRESULFU: 125 150 175 200 285 250 300 ° C 350 °

RATION

DMS 0 0 0 0 0.4 1.9 4.6 5.6

DMDS: 0 0 0.6 1.7 3.3 4.4 5.2 5.6

DMTS: 0.4 1.9 4.2 5 5.2 5.6 5.6 5.6

DETS: 0.6 2.4 4.7 5.3 5.5 5.6 5.6 5.6

DMTES: 1.4 3.2 4.9 5.4 5.6 5.6 5.6 5.6

DEBTS: 2, 2 3.8 5.0 5.5 5.6 5.6 5.6 5.6

DTBPS: 1.9 3.7 5.0 5.5 5.6 5.6 5.6 5.6

MERS 4: 1.0 3.1 4.9 5.4 5.6 5.6 5.6 5.6- Polysulfides and mixtures of polysulfides are much more active, at a given temperature, than DMDS and DMS. This better activity of the sulfurizing agent is accompanied by better sulphurization of the catalyst at low temperature (higher sulfur content) Tests No. 2

A NiMo catalyst was tested _, under conditions identical to ¹ tests n ° 1.

TABLE 3

RATE OF ACTIVE SULFUR (S)

PRESULFURATION TEMPERATURE

AGENT 125 150 ^* 175 200 ° C 225 ° C 250 ° C 275 300 ° C 350 ° C

DMS 0 0 0 0 0 0 10 80 100

DMDS 0 0 0 0 6 17 63 90 100

DMTS 0 0 0 2 20 38 75 96 100

DETS 0 0 4 20 59 80 92 98 100

DMTES 0 0 20 45 58 65 95 99.5 100

DEBTS 0 7 20 45 85 95 99 99.8 100

DTBPS 0 7 21 47 85 95 99.5 100 100

MERS4 0 * 3 11 30 68 89 96 99 100

TABLE 4 PERCENTAGES OF SULFUR FIXED ON THE CATALYSTS AFTER EACH ISOTHERMAL PRESULFURATION

PRESULFURATION TEMPERATURE

AGENT

OF

PRESUL¬ 125 150 175 200 ° C 225 ° C 250C ° 300 ° C 350C °

FURATION

DMS 0 0 0 0 0.8 3.1 4, 4 5

DMDS 0 0.1 0.7 1.5 2.4 3.4 4, 6 5

DMTS 0 0.6 1.1 2.7 3.8 4.6 5 5

DETS 0.2 1.5 2.2 3.6 4.5 4.9 5 5

DMTES 1.9 3 4 4.3 4.8 5 5 5

DETES 2.4 4.3 4.2, 5 4.9 5 5 5

DTBPS 2 3.3 4.2 4.5 4.9 5 5 5

MERS 4 1.6 2.9 4.1 4.4 4.8 4.9 5 5

Polysulfides and mixtures of polysulfides are more active than DMDS and DMS, and allow a lower temperature sulfidation. EXAMPLE 3

PILOT CATALYST SULFURIZATION

The catalyst chosen is manufactured by PROCATALYSE e sold under the name of HR 306. This catalyst is a conventional catalyst representative of the catalysts currently available. It contains 2.8% by weight of CoO and 14.7% by weight of MoO-, deposited on a alumina whose surface area measured by BET is 292m ~ Vg.

The volume of catalyst loaded is 400 ml. The height-to-diameter ratio of the catalytic bed is approximately 10. The catalyst is dried overnight under hydrogen at 150 ° C. The sulfurizing agent is diluted at a rate of 1.5% by weight of the sulfur element in a light gas oil free of unsaturated compound having the following properties: density at 15 ° C = 0.8508 sulfur = 0.9% by weight The feed is injected at the bottom of the reactor at 150 ° C. under the following operating conditions:

Pressure 40 bar Spatial speed 1 Flow H / HC 200 1/1

The temperature of 150 ° C is maintained for 14 hours. For other temperatures, a temperature rise by programming of 20 ° C / h is made up to the test temperature and maintained in level for 12 hours. The unit is then cooled and the catalyst discharged under nitrogen.

Table 5 summarizes the percentage of carbon and sulfur deposited on a catalyst sulfurized by DMDS l diethyltetrasulfide (DETES) and dimethyltetrasulfur (DMTES).

TABLE 5

Carbon Sulfur

DMDS 220 ° C 4.15 4.32

DETES 150 ° C 3.26 5.71

180 ° C 3.75 5.73

220 ° C 3.65 6.68

DMTES 150 ° C 3.34 5.67

180 ° C 4.07 5.65

220 ° C 4.13 6.55

The use of polysulphide allows more efficient sulphurization while reducing the formation of coke.

EXAMPLE 4

PERFORMANCE OF SULPHIDE CATALYSTS

The catalyst was sulfurized under identical conditions

Example 3 with the:

DMDS (dimethyldisulfide)

DETES (diethyltetrasulfide)

DMTES (dimethyltetrasulfide) After in situ sulfurization of the catalyst, the charge of the DS OURAL, the main analytical characteristics of which are given below.

DSV OURAL Mvl5 0.9275

Mv80 0.8836

S. 2.09%

N 520 b, Asia

Ni 0.3

V 0.6

The operating conditions for the injection at the bottom of the reactor are as follows:

Spatial speed

Pressure 60 bars

Hydrogen cover 250 ^' 1/1 charge The performance of the catalyst is evaluated by measurement on effluents, sulfur, total nitrogen, basic nitrogen and density.

These measurements make it possible to determine the removal rates of the element considered. In Table 5 we summarize the rates of hydrodesulfurization (HDS), total hydrodesitrogenation (HDN) and basic (HDN.) As well as

^' lowering the charge density (^ d).

TABLE 5

Agent Temp. HDS HDNt HDNb March ¹⁰ Δ sulfurizing DMDS 340 80.5 20.3 0 20.5 340 82 21.2 13.5 ^Detes' DMTES 21.1 340 82 21 9.6 20.5

(S, N _t , N load - (S, N _b ) effluent

HD (S, N, N _b ) = 100

(S N, N,) charge A = density charge - effluent density.

Claims

Process for the sulfurization of a catalyst containing at least one active metal in the form of oxide deposited on a porous support, by simultaneous passage of hydrogen and of a hydrocarbon feed containing a sulfuran agent, characterized in that the sulfurizing agent is at minus an organic polysulfide of general formula or R and R ′, which are identical or different, represent a linear or branched, saturated or unsaturated C 1 to C alkyl radical and n is between 3 and 10.

2 - Method according to claim 1 characterized in that n represents an average value between 3 and 5.

3 - Process according to claims 1 or 2 characterized in that the polysulfide is dimethyltrisulfide, l diethyltrisulfide, mixtures of dimethylpolysulf re containing on average four sulfur atoms, mixtures of diethylpolysulfides containing on average four sulfur atoms or -mixtures ^" d diterbutylpoïysufures containing on average five sulfur atoms per molecule.

4 - Process according to claims 1 or 2 characterized in that the polysulfides are mixtures originating from the sulfurization of residues of MEROX units.

5 - Method according to one of claims 1 to characterized in that the hydrocarbon feed contains 0.1 to 10% by weight and preferably 0.5 to 5% expressed e sulfur, sulfur compounds.

6 - Method according to one of claims 1 to characterized in that the temperature of the first sulphurization stage is between 150 and 250 ° C.

7 - Method according to one of claims 1 to characterized in that one uses a flow rate of 100 to 300 1 normal hydrogen by 1 normal gas.

8 - Method according to one of claims 1 to 7 characterized in that the pressure is between 1 and 300 bars and preferably between 15 and 150 bars and 3 the space velocity expressed in m of liquid load

3 injected per m of catalyst and hour is between 0.1 and 15 and preferably between 0.5 and 3.

9 - Process according to one of claims 1 to characterized in that the active metal is chosen from the metals of groups VI B and VIII of the periodic classification of the elements, such as molybdenum, tungsten, iron, cobalt, nickel, rhodium, platinum or palladium.

10- Method according to one of claims 1 to characterized in that the metals of groups VI B e VIII are used in admixture with metals d groups of lanthanides such as lanthanum, ceriu or neodymium. 1- Method according to one of claims 1 to 1 characterized in that the hydrocarbon feed is crude oil or a petroleum fraction, such as gasolines, middle or heavy distillates and the residues of heat or catalytic treatments.