FR2718146A1 - A two stage process for the treatment of heavy petroleum cuts - Google Patents

Abstract

A process for the prodn. of oils with a viscosity index between 95-150 from heavy petroleum cuts with a B.Pr greater than 380 deg.C by a two-stage procedure:- a) In the first stage the cut is contacted with a hydro treatment catalyst contg. a gp. VI and gp. VIII element on an amorphous support in the presence of H2 at 350-430 deg.C and 0.5-20 MPa: the VVH is 0.1-10<->1 h and the amt. of H2 such that the vol ratio of H2:hydrocarbons is 150-2000. b) In the second stage at least part of the effluent from (a) is contacted with a hydro-isomerisation catalyst in the presence of H2 at 200-450 deg.C 0.7-25 MPa VVH of 0.1-10h <->1 and vol. H2:hydrocarbons of 100-2000. The catalyst comprises 0.05-10% (wt.) of a gp. VIII metal on amorphous SiO2/Al2O3 : the support contains 5-70% SiO2 and has a surface area of 100-500 m<2>/g with a mean pore dia. of 1-12 nm. The vol. of the pores of mean dia +/- 3nm comprises more than 40% of the total porosity the dispersion of the noble metal being 20-100% and the coeff of distribution being greater than 0.1.

Description

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The invention relates to a process for the production, from heavy petroleum fractions, of oil bases, that is to say oils having viscosity indices (VI) of between 95 and 150, and more particularly

between 105 and 140.

These feeds have boiling points greater than 380 C. They are, for example, vacuum distillates, deasphalted residues or their mixtures. For a long time, the French Petroleum Institute has developed processes for the production of oily bases from these fillers, whether this

either by extraction (or furfurol for example), or by hydrorefining.

Figure 1 attached illustrates the prior art. The petroleum (P) is subjected to atmospheric distillation in the reactor 1 to produce kerosene (K), light gas oil (GI), heavy gas oil (GL) fractions. Gasoline and gas (E + G) are separated. The atmospheric residue RA is vacuum distilled in reactor 2 from which a gaseous fraction G emerges, medium vacuum distillates (in our example we only considered three vacuum distillates M1, M2 and M3 but being of course that this number can be modified according to the needs of the refiner) and a vacuum residue RSV. The RSV residue is subjected to deasphalting in a unit 12, the asphalt A is separated and the deasphalted residue is sent to a reactor 3 to undergo either extraction of the aromatics by solvent (for example furfurol) or hydrorefining. The M distillates are also treated in reactor 3 alone or as a mixture with one (or more) other M distillate (s) and / or the deasphalted vacuum residue. In the case of hydrorefining, an amorphous catalyst is used comprising nickel and molybdenum supported on alumina or silica alumina (patent FR-A-1,465,372). The actual oil is obtained after a solvent dewaxing operation (reactor 4) which consists in eliminating, from the effluents of the reactor 3, the products essentially consisting of paraffinic molecules having a pour point too high to be able to obtain oil having a low pour point (typically -10 C to -300C). This oil is stabilized in reactor 5 by a finishing hydrotreatment (hydrofinishing) for

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produce base oils (H). Extensive hydrotreatment of paraffins and waxes (C) in reactor 6 leads to quality paraffins and waxes

food (CA).

The Applicant has developed a new catalytic process comprising two stages which thus stands out clearly from the traditional catalytic hydrorefining processes which themselves comprise only one.

step and a single catalyst.

More precisely, the object of the invention is a process for treating heavy hydrocarbon-based petroleum fractions, with a boiling point.

essentially above 380 C, for the production of oil bases.

In a first step, the aim of which is to substantially remove the heteroatoms such as, in particular, sulfur or nitrogen, the cut is brought into contact, in the presence of hydrogen, with at least one hydrotreatment catalyst containing a amorphous support, at least one element of group VI and at least one element of group VIII, at a temperature between 350 and 430 C, under a pressure between 0.5 and 20 MPa, the space velocity being between 0.1 and 10h-1 and the quantity of hydrogen introduced such as the volume ratio

hydrogen / hydrocarbon is between 150 to 2000.

The first step uses a catalyst having a very strong denitrogenation activity. Those described in patent EP-A-297,949 are particularly suitable. This operation therefore makes it possible to eliminate two types of compounds (sulfur-containing and nitrogen-containing) which are inhibitors of the hydroisomerization catalyst. At the same time, due to the severe operating conditions required by the denitrogenation, the hydrogenation of

aromatics will take place.

In general, the catalysts of the first stage consist essentially of a non-zeolitic support and of at least one metal or metal compound having a hydro-dehydrogenating function. The catalyst comprises: an inorganic matrix, such as alumina and optionally as described in patent EP-297,949 boron or a compound of boron and phosphorus or a compound of phosphorus and at least one metal or compound of metal from the group VIB and at least one metal

or compound of a metal of group VIII of the periodic table.

Preferably, according to patent EP-297,949, the sum of the quantities of boron and phosphorus, expressed respectively by weight of boron trioxide and phosphorus pentoxide, relative to the weight of support, is approximately 5 to 15% and the boron to phosphorus atomic ratio is about 1: 1 to 2: 1 and at least 40% of the total pore volume of the finished catalyst is contained in pores with an average diameter greater than 13 nanometers. Preferably, the amount of metal from group VI, such as molybdenum or tungsten, is such that the atomic ratio of phosphorus to metal from group VIB is about 0.5: 1 to 1.5: 1; the amounts of Group VIB metal and Group VIII metal, such as nickel or cobalt, are such that the Group VIII metal to Group VIB metal atomic ratio is about 0.3: 1 to 0.7 : 1. The quantities of metal of group VIB expressed by weight of metal relative to the weight of finished catalyst is about 2 to 30% and the quantity of metal of group VIII expressed by weight of metal relative to the weight of

finished catalyst is about 0.1 to 15%.

Catalysts based on NiMo on alumina, NiMo on doped alumina

with boron and / or phosphorus and NiMo on silica alumina are preferred.

Advantageously, eta or gamma alumina will be chosen.

Conventionally, the operation is carried out in this first step with temperatures of between 350 and 430 C, and preferably between 360 and 410 C, with pressures of between 0.5 and 20 MPa, and preferably 0.7 and 15 MPa. , with space speeds between 0, 1 and 10h-1, and

preferably 0.2 and 5 h-1.

Advantageously, the operator will choose the temperature of this first step as a function of the viscosity index that he wishes to obtain on

the oil base at the end of this step.

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At least part of the product obtained at the end of this first step (it being understood that it could possibly be got rid of the H2S and NH3 gases and / or possibly be fractionated), is sent to a second catalyst

in a second step where the hydroisomerization reaction takes place.

The reaction takes place in the presence of hydrogen, at a temperature between 200 and 450 C, under a pressure between 0.7 and 25 MPa, the space speed being between 0.1 and 10h-1 and the amount of hydrogen introduced such that the hydrogen / hydrocarbon volume ratio is between 100 to 2000, with a hydroisomerization catalyst essentially consisting of 0.05-10% by weight of at least one metal from group VIII deposited on an amorphous support of silica-alumina, said support containing 5-70% by weight of silica and having a specific surface area of -500m2 / g and said catalyst having an average pore diameter of 1-1 2nm, the volume of the pores having a diameter between the diameter average + 3nm representing more than 40% of the total pore volume, the dispersion of the noble metal being between 20 and 100% and the distribution coefficient

of the noble metal in the catalyst being greater than 0.1.

The characteristics of the hydroisomerization catalyst are in more detail: Silica content: the support used for the production of the catalyst described in the context of this patent is composed of silica SiO2 and alumina A1203. The silica content, expressed as a percentage by weight, is between 5 and 70 and preferably between 20 and 60% and even more preferably between 22 and 45. This content is perfectly measured using X-ray fluorescence. Nature of the noble metal: for this particular type of reaction, the metallic function is provided by a noble metal from group VIII of the classification

periodic elements and more particularly platinum.

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Noble metal content: the noble metal content, expressed in% by weight of metal relative to the catalyst, is between 0.05 to 10 and more

preferably between 0.1 and 5.

Dispersion of the noble metal: the dispersion, representing the fraction of metal accessible to the reactant relative to the total amount of metal in the catalyst, can be measured, for example, by H2 / 02 titration. The metal is reduced beforehand, that is to say that it undergoes a treatment under a flow of hydrogen at high temperature under conditions such that all the platinum atoms accessible to the hydrogen are transformed into metallic form. Then, a flow of oxygen is sent under suitable operating conditions so that all the reduced platinum atoms accessible to oxygen are oxidized in the form of PtO2. By calculating the difference between the quantity of oxygen introduced and the quantity of oxygen leaving, we can access the quantity of oxygen consumed; thus, it is then possible to deduce from this latter value the quantity of platinum accessible to oxygen. The dispersion is then equal to the ratio of the quantity of platinum accessible to oxygen to the total quantity of platinum in the catalyst. In our case, the dispersion is between 20% and 100% and preferably

between 30% and 100%.

o Distribution of the noble metal: the distribution of the noble metal represents the distribution of the metal inside the catalyst grain, the metal being able to be well or poorly dispersed. Thus, it is possible to obtain the poorly distributed platinum (for example detected in a ring whose thickness is clearly less than the radius of the grain) but well dispersed, that is to say that all the platinum atoms, located in crown, will be accessible to reagents. In our case, the distribution of the platinum is good, that is to say that the profile of the platinum, measured according to the Castaing microprobe method, presents

a distribution coefficient greater than 0.1 and preferably greater than 0.2.

BET surface: the BET surface of the support is between 100m2 / g and 500m2 / g and preferably between 250m2 / g and 450m2 / g and

even more preferably between 310m2 / g and 450m2 / g.

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Average pore diameter: the average pore diameter of the catalyst is measured from the pore distribution profile obtained using a mercury porosimeter. The mean pore diameter is defined as being the diameter corresponding to the cancellation of the derivative curve obtained from the mercury porosity curve. The average diameter

of the pores, thus defined, is between nm (1 * 10-9meter) and 12nm (12 * 10-

9meter) and preferably between 2, Snm (2.5 * 10-9meter) and 11nm (11 * 10-9meter) and even more preferably between 4nm (4 * 10-9meter)

and 10.5nm (10.5 * 10-9meter).

Pore distribution: the catalyst referred to in this patent has a pore distribution such that the pore volume of the pores whose diameter is between the average diameter as defined previously reduced by 3 nm and the average diameter as defined previously 1 5 increased of 3nm (i.e. the mean diameter + 3nm) is greater than 40% of the total pore volume and preferably between 50% and 90% of the total pore volume and more advantageously still between 50% and 80% of the

total pore volume and better still between 50% / and 70% of the total pore volume.

Overall pore volume of the support: it is generally less than 1.0ml / g and preferably between 0.3 and 0.9ml / g and even more

advantageously less than 0.85 ml / g.

The preparation and shaping of the silica-alumina is carried out by standard methods well known to those skilled in the art. Advantageously, prior to the impregnation of the metal, the support can undergo calcination such as for example a heat treatment at 300- 750 C (600 C preferred) for 0.25-10 hours (2 hours preferred) under 2- 30 %

volume of water vapor (7.5% preferred).

The metal salt is introduced by one of the usual methods used to deposit the metal (platinum for example) on the surface of a support. One of the preferred methods is dry impregnation which consists in introducing the metal salt into a volume of solution which is equal to the pore volume of the mass of catalyst to be impregnated. Before the operation of

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reduction, the catalyst may undergo calcination such as for example a treatment in dry air at 300-750 C (520 C preferred) for 0.25-10 hours

(2 hours preferred).

Before use in the hydroisomerization reaction, the metal contained in the catalyst must be reduced. One of the preferred methods for carrying out the reduction of the metal is the treatment under hydrogen at a temperature of between 150 ° C. and 650 ° C. and a total pressure of between 0.1 and 25 MPa. For example, a reduction consists of a plateau at 150 C for 2 hours then a rise in temperature to 450 C at a rate of 1 C / min then a plateau of 2 hours at 450 C; throughout this reduction step, the hydrogen flow rate is 1000 liters of hydrogen per liter of catalyst. Note also that any ex-situ reduction method

is suitable.

The catalyst as described makes it possible to obtain a large quantity of isoparaffinic products resulting from the hydroisomerization of the molecules present in the starting charge and which can then

be used as components of lubricants.

The feed entering this second stage must have a sulfur content of less than 1000 ppm by weight and preferably less than 500 ppm by weight and even more preferably less than 300 ppm by weight and the nitrogen content of less than 200 ppm by weight and preferably less than

100ppm weight and even more preferably less than 50ppm weight.

The metal content of the filler such as nickel and vanadium is extremely low, that is to say less than 50 ppm by weight and in such a way

more advantageous less than 10ppm weight.

The operating conditions used for this reaction are a temperature from 200 C to 450 C and preferably from 250 C to 450 C or better 430 C and advantageously greater than 340 C, a partial pressure of hydrogen of 0.7-25 MPa, in general from 2MPa to 25MPa and preferably between 3MPa and 20MPa or even between 0.7-15MPa, an hourly volume speed (space speed) between 0.1 and 10 h-1

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and preferably between 0.2 and 5 h-1 and advantageously between 0.2 and 2 h-1 and a hydrogen / hydrocarbon volume ratio of between 100

and 2000 liters and preferably between 150 and 1500.

The product thus obtained at the end of the second step then undergoes the traditional treatment found in an oil production line such as dewaxing. Note however, that if the starting charge is particularly chosen, that is to say that the distillation cut is, for example, obtained from a very isoparaffinic crude and if the operating conditions of stages 1 and 2 are adjusted, it It is possible to do without the dewaxing operation. At the end of the possible dewaxing operation, the product can undergo any suitable finishing treatment such as, for example, a very thorough hydrogenation so as to obtain

oils having food grade.

The method which is the subject of the invention is illustrated for example in FIG. 2.

In the same way as in the prior art (FIG. 1), the crude oil P is treated by atmospheric distillation (reactor 1) then by vacuum distillation (reactor 2). In FIG. 2, for the sake of simplification, we have mentioned only one effluent M from the vacuum distillation, it being understood that the refiner will have the number of effluents available according to its needs. According to the invention, in a hydrotreatment reactor 7 constituting the first step of the process according to the invention, a feed is treated, here consisting of a vacuum distillate alone or as a mixture or of the deasphalted vacuum residue or both ( distillate and residue). We wanted to represent these options in the figure in the form of dotted lines. In the case illustrated here, all of the effluent from the reactor 7 passes into the hydroisomerization reactor 8 constituting the second stage. An oil H emerges which can optionally be (dotted lines in the figure) dewaxed in a unit 9. Optionally, this dewaxing can be followed by a finishing hydrotreatment in a reactor 10. According to a variant, the heavy fraction obtained at From reactor 10 (mainly paraffins and waxes) undergo another very extensive hydrotreatment (reactor 11) to provide food grade products. It is also advantageous to provide for the recycling of

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paraffins extracted from reactor 9 or to hydrotreatment reactor 7

or, preferably, to the hydroisomerization reactor 8.

The example presented below illustrates the characteristics of the invention without, however, limiting its scope. Comparative example (not in accordance with the invention) In a reactor, the conventional hydrorefining catalyst HTH546 (Ni Mo on doped alumina) obtained from the company Procatalyse is charged. Example according to the invention First stage catalyst: in a first reactor , the conventional hydrotreatment catalyst HR348 obtained from the company Procatalyse (16.5% MoO3, 2.7% NiO) is charged; which is particularly suitable for

the hydrodenitrogenation reaction.

Second stage catalyst: the support is a silica-alumina used in the form of extrudates. It contains 29.1% by weight of SiO2 silica and 70.9% by weight of A1203 alumina. The silica-alumina, before adding the noble metal, has a surface area of 389 m 2 / g and an average pore diameter of 6.6 nm. The corresponding catalyst is obtained after impregnation of the noble metal on the support. The platinum salt Pt (NH3) 4C12 is dissolved in a volume of solution corresponding to the total pore volume to be impregnated. The solid is then calcined for 2 hours in dry air at 520 ° C. The platinum content is 0.60% by weight. Measured on the catalyst, the pore volume is equal to 0.72 cm3 / g, the BET surface area equal to 332 m2 / g and the average pore diameter of 6.5 nm and the pore volume corresponding to the pores whose diameter is between 3 , 5nm and 9.5nm is 46ml / g or 61% of the

total pore volume.

Description of the vacuum distillate charge:

Description of the vacuum distillate charge:

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The feed is a vacuum distillate whose composition is given

in Table 1.

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Table 1

d15 / 4 0.935 V1 00 oC (m2 / s) 9.5.10-4 Sulfur (% weight) 2.73 Nitrogen (ppm) 1350 Distillation Starting point 353

% 394

% 428

% 455

% 470

% 485

% 516

% 546

End point 560 Comparison of the performances obtained with a conventional hydrorefining process and the new two-step process In the table below, we have grouped the operating conditions and the characteristics of the products obtained with the feed described above in a conventional d 'hydrorefining with the catalyst as described above or treated in the new claimed process. The operating conditions have been carefully chosen so that

the overall conversion is identical (or very close) in both cases.

It therefore clearly appears that the method according to the invention makes it possible to significantly improve, compared with the prior art, the viscosity index (gain of 10 points), the viscosity (gain of 0.35 × 10-6 m2 / s or about 20%) and

also the pour point.

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This process therefore very advantageously replaces the previous processes which used either an aromatics extraction unit or hydrorefining. prior art charge | invention P total (MPa) / 14

H2 / HC (VI) / 1000

VVH (h-) / 0.5 1/1 Temp. (C) / 385 380/360 d154 0.935 0.876 0.869 S (ppm by weight) 27 300 48 39 N (ppm by weight) 1350 1.7 1, 5 400 - (% by weight) 6 22.6 24.4 400 + (% by weight ) 94 77.4 75.6 Residue quality 400+ yield 20 48 65 dewaxing (%) viscosity 9.9 6.25 5.90 at 100 C (m2 / s) Xl 0-6 X10-6 Xl 0-6 Vl 94 115 125 Flow point (C) -12 -12 -15

Note: 1/1 means 1 h-1 in the first step and 1 h-1 in the second.

380/360 means 380 C in the first step and 360 C in the second.

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Claims (15)

1 - Process for the production of oils with a viscosity index of between and 150, from heavy hydrocarbon-based petroleum cuts with a boiling point essentially greater than 380 C, characterized in that: * in a first step, the cut is put in contact, in the presence of hydrogen, with at least one hydrotreatment catalyst containing, on an amorphous support, at least one element from group VI and at least one element from group VIII, at a temperature between 350 and 430 C, under a pressure between 0.5 and 20 MPa, the space speed being between 0.1 and 10h-1 and the quantity of hydrogen introduced such that the hydrogen / hydrocarbon volume ratio is between 150 and 2000, * in one second step, at least part of the effluent obtained at the end of the first step is brought into contact, in the presence of hydrogen, at a temperature of 200-450 C, under a pressure of 0.7-25 MPa, the hourly space velocity being 0.1-10h-1 and the volume rate H2 / hydr ocarbons of 100-2000, with a hydroisomerization catalyst essentially consisting of 0.05-10% by weight of at least one metal from group VIII deposited on an amorphous support of silica-alumina, said support containing 5-70% by weight. weight of silica and having a specific surface area of 100-500 m2 / g and said catalyst having an average pore diameter between 1-12 nm, the volume of pores with a diameter between the average diameter + 3 nm representing more than 40% of the total porous material, the dispersion of the noble metal being between 20-100%, and the coefficient of distribution of the noble metal in the catalyst being greater than 0.1. 2- Process according to claim 1, characterized in that the effluent from the first step is freed of H2S and NH3 gases before being treated in the second step 3- Method according to one of claims 1 or 2, characterized in that The effluent from the first step is fractionated, and at least one of the fractions obtained is treated in the second step 14 2718146 4 - Method according to one of the preceding claims, characterized in that the support of the hydroisomerization catalyst has a volume overall porous less than 1.0 mVl / g. - Method according to one of the preceding claims, characterized in that the support for the hydroisomerization catalyst has an overall pore volume of at least 0.3 ml / g and less than 0.9 ml / g 6 - Method according to one of the preceding claims, characterized in that the support of the hydroisomerization catalyst has a volume overall porous of at least 0.3 ml / g and less than 0.85 ml / g. 7 - Method according to one of the preceding claims, characterized in that the hydroisomerization catalyst has an average diameter of pores between 2.5 and 11 nm. 8 - Method according to one of the preceding claims, characterized in that the hydroisomerization catalyst has an average diameter of the pores between 4 and 10.5 nm. 9 - Method according to one of the preceding claims, characterized in that in the hydroisomerization catalyst, the volume of porous pores with a diameter between the mean diameter + 3 nm is included between 50 and 90% of the total pore volume. - Method according to one of the preceding claims, characterized in that in the hydroisomerization catalyst, the volume of the pores of the pores with a diameter between the mean diameter + 3 nm is included between 50 and 80% of the total pore volume. 11 - Method according to one of the preceding claims, characterized in that in the hydroisomerization catalyst, the volume of the pores of the pores with a diameter between the mean diameter + 3 nm is included between 50 and 70% of the total pore volume. 1 5 2718146 12 - Method according to one of the preceding claims, characterized in that the hydroisomerization catalyst support contains 22-60% by weight of silica. 13 - Method according to one of the preceding claims, characterized in that the hydroisomerization catalyst support contains 22-45% by weight of silica. 14 - Method according to one of the preceding claims, characterized in that the catalyst support has a BET surface area of 310- 450m2 / g - Method according to one of the preceding claims, characterized in that the catalyst of the first step is chosen from the group formed by a catalyst based on nickel and molybdenum on alumina, a catalyst based on nickel and molybdenum on alumina doped with boron and / or phosphorus and a catalyst based on nickel and molybdenum on silica alumina. 16 - Method according to one of the preceding claims, characterized in that the first stage operates at a temperature of 360-41 0 C, under a pressure of 0.7-20MPa, with space velocities of 0.2-5h-1. 17 - Method according to one of the preceding claims, characterized in that the second stage operates at a temperature of 250-450 C, under a pressure of 0.7-15MPa, with space velocities of 0.2-5h-1 and the hydrogen on hydrocarbon rate between 150 and 1500. 18 - Method according to one of the preceding claims, characterized in that the second stage operates at a temperature above 340 C.