EP0649896A1 - Process for the simultaneous production of middle distillates and lubrification oils from heavy petroleum fractions - Google Patents

Abstract

Process for joint production of middle distillates and of oil bases (viscosity index between 95 and 150) especially from vacuum distillates and/or deasphalted oils. The process includes a first stage in which the feedstock is brought into contact with an amorphous catalyst filled with at least one metal or metal compound which has a hydrodehydrogenating function, such as Ni, Mo, W or Co, at a temperature of between 350 and 430 DEG C, a pressure of between 5 and 20 MPa, a space velocity of between 0.1 and 5 h<-1> and in the presence of hydrogen in an H2/HC volume ratio = 150 to 2,000, the product originating from the first stage is brought into contact (in a second stage), with a second catalyst including a support, a zeolite Y, at least one element of group VIB and at least one metal of group VIII at a temperature of between 350 and 430 DEG C, a pressure of between 5 and 20 MPa and a space velocity of between 0.1 and 5 h<-1>.

Description

The invention relates to a process for the joint production, from heavy petroleum fractions, middle distillates and bases of high viscosity oils, that is to say oils having viscosity indices (VI) of between 95 and 150 , and more particularly between 120 and 140.
The fillers have boiling points above 380 ° C. These are for example vacuum distillates, deasphalted oils or their mixtures.

The Institut Français du Pétrole has long developed processes for the production of oily bases from these fillers, whether by extraction (furfurol for example) or by hydrorefining. In the latter case, amorphous catalysts comprising nickel and molybdenum supported on alumina or silica alumina are used (patent FR-A-1,465,372).

It is also known to proceed in 2 stages on 2 different amorphous catalysts. Thus in patent USP-3,642,612, the charge is treated in the presence of hydrogen on a first catalyst containing metals from groups VI and VIII deposited on a weakly acid support (alumina) then on a second catalyst also containing metals from groups VI and VIII but deposited on a more acidic support (silica-alumina).

It is proposed to produce oil bases of VI at least equal compared to a process on amorphous catalysts, but having higher viscosities (compared to a process on amorphous catalysts) to isoconversion into distillates.

In other words, this process allows a greater production of middle distillates while retaining characteristics of similar oils.

The Applicant has developed a flexible process, adaptable to various cuts, and allowing the operator to control the conversion and the viscosity.

More specifically, the subject of the invention is a process for treating heavy hydrocarbon petroleum fractions, with a boiling point above 380 ° C., for the improved production of middle distillates together with the production of oil bases having an index of viscosity between 95 and 150, process in which, in a first step , the cut is brought into contact, in the presence of hydrogen, with at least one catalyst containing on an 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 5 and 20 MPa, the space velocity being between 0.1 and 5h⁻¹ and the quantity of hydrogen introduced such that the hydrogen / hydrocarbon volume ratio is between 150 to 2000, the product resulting from said first stage is brought into contact, in a second stage , with a catalyst containing a support, at least one group VI element, at least one group VIII element and a Y zeolite, at a temperature between 350 and 430 ° C, at a pressure between 5 and 20 MPa, the space speed being included between 0.1 and 5h⁻¹ and the product from said second stage is fractionated, on the one hand into middle distillates, and on the other hand into residue, containing the oil bases.

In the first step of the process, the charge and the added hydrogen are brought into contact with a first catalyst. The quantity of hydrogen supplied is such that the volume ratio H₂ / hydrocarbons is between 150 and 2,000 and preferably 500 and 1,500.

The catalyst of the first stage essentially consists of a non-zeolitic support and of at least one metal or metal compound having a hydro-dehydrogenating function.

The support is preferably essentially constituted (based on) of alumina or silica amorphous alumina it can also contain boron oxide, magnesia, zirconia, titanium oxide, clay , or a combination of these oxides. The hydro-dehydrogenating function is preferably fulfilled by at least one metal or compound of metal from the molybdenum, tungsten, nickel and cobalt group. One can generally use a combination of metals from group VI (molybdenum and / or tungsten in particular) of the periodic table.

This catalyst may advantageously contain phosphorus; in fact, it is known in the prior art that the compound brings two advantages to hydrotreatment catalysts: ease of preparation during in particular the impregnation of nickel and molybdenum solutions, and better hydrogenation activity.

The catalysts NiMo on alumina, NiMo on alumina doped with boron and / or phosphorus and NiMo on silica alumina are preferred.

Advantageously, choose η or γ alumina.

The total concentration of oxides of metals from groups VI and VIII is between 5 and 40% by weight and preferably between 7 and 30% and the weight ratio expressed as metal oxide between metal (or metals) of group VI on metal (or metals) of group VIII is between 20 and 1.25 and preferably between 10 and 2. The concentration of phosphorus oxide P₂O₅ will be less than 15% by weight and preferably 10% by weight.

During the first step, the use of a catalyst favoring hydrogenation over cracking, used under appropriate thermodynamic and kinetic conditions, allows a significant reduction in the content of condensed polycyclic aromatic hydrocarbons. Under these conditions, most of the nitrogen products in the feed are also processed. This operation therefore makes it possible to eliminate two types of compounds which are known to be inhibitors of the zeolitic catalyst.

Conventionally, this operation is carried out in this first step with temperatures between 350 and 430 ° C, and preferably between 370 and 410 ° C, with pressures between 5 and 20 MPa, and preferably 7 and 15 MPa, with space velocities between 0.1 and 5 h⁻¹, and preferably 0.3 and 1.5 h⁻¹.

Advantageously, the operator will choose the temperature of this first stage as a function of the viscosity index which he wishes to obtain on the oil base at the exit of this stage, which will preferably be between 90 and 130, and better still between 90 and 120, even 90 and 110.

The product obtained at the end of this first stage is sent to a second catalyst in a second stage. Advantageously, the effluent is sent in the second step without intermediate separation of ammonia and hydrogen sulfide. Such separation can, in another embodiment of the method, be provided.

The second stage catalyst essentially consists of a zeolite, a support and a hydro-dehydrogenating function.

The hydro-dehydrogenating function consists of a combination of metals from groups VI (in particular molybdenum and / or tungsten) and metals from group VIII (especially cobalt and / or nickel) of the periodic table. This catalyst may also advantageously contain phosphorus.

The total concentration of metal oxides of GVIII and VI is between 1% and 40% by weight and preferably between 3 and 30% and advantageously between 8-40%, even 10-40% and better still 10-30%. The weight ratio expressed as metal oxides between metal (or metals) of group VI on metal (or metals) of group VIII is between 20 and 1.25 and preferably between 10 and 2. The concentration of phosphorus oxide (P₂O₅) will be less than 15% and preferably 10% by weight.

The support is chosen from the group consisting of alumina, silica, silica alumina, alumina-boron oxide, magnesia, silica-magnesia, zirconia, titanium oxide, clay, only or in mixtures.

The zeolite content by weight is between 2 and 80% and preferably between 3 and 50% relative to the final catalyst, and advantageously between 3-25%.

The zeolite can optionally be doped with metallic elements such as, for example, the metals of the rare earth family, in particular lanthanum and cerium, or noble or non-noble metals of group VIII, such as platinum, palladium, ruthenium, rhodium, iridium, iron and other metals such as manganese, zinc, magnesium.

An acidic zeolite HY is particularly advantageous and is characterized by different specifications: a SiO₂ / Al₂O₃ molar ratio of between approximately 8 and 70 and preferably between approximately 12 and 40: a sodium content of less than 0.15% by weight determined on the zeolite calcined at 1100 ° C. a crystalline parameter has elementary mesh between 24.55 x 10⁻¹⁰ m and 24.24 x 10⁻¹⁰ m and preferably between 24.38 x 10⁻¹⁰ m and 24, 26 x 10⁻¹⁰m; a CNa capacity for taking up sodium ions, expressed in grams of Na per 100 grams of modified zeolite, neutralized then calcined, greater than approximately 0.85 a specific surface area determined by the BET method greater than approximately 400 m² / g and preferably greater than 550 m² / g, a water vapor adsorption capacity at 25 ° C for a partial pressure of 2.6 torrs (i.e. 34.6 MPa), greater than approximately 6%, a porous distribution comprising between 1 and 20% and preferably between 3 and 15% of the pore volume contained in pores with a diameter between 20 x 10⁻¹⁰ m and 80 x 10⁻¹⁰m, the rest of the pore volume being contained in pores with a diameter less than 20.10 ⁻¹⁰ m.

A preferred catalyst contains nickel, molybdenum, a Y zeolite as defined above and alumina.

The operating conditions under which this second step is carried out are important.

The pressure will be maintained between 5 and 20 MPa and preferably 7 to 15 MPa, the space speed will be between 0.1 h⁻¹ and 5 h⁻¹ and preferably between 0.3 and 1.5 h⁻¹.

The temperature is adjusted on the second step, so as to obtain the desired viscosity and VI. It is between 350 and 430 ° C, and in general it is advantageously between 370 and 410 ° C, even 390 ° C.
The Applicant has surprisingly found that the viscosity of the residue is less reduced than on amorphous catalysts for the same level of conversion.

Thus, by the combination of an adjustment of the conditions of the first step, which makes it possible to obtain an intermediate viscosity and of a viscosity index, with an adjustment of the conditions of the second step, which makes it possible to adjust the viscosity and the VI at the desired values, the applicant has succeeded in a new and surprising way in obtaining a flexible process for the manufacture of high viscosity oils having high VIs and middle distillates.

The product from the second stage is then fractionated so as to obtain, on the one hand, the middle distillates and, on the other hand, the residue containing the oil bases.

Preferably, the process is carried out without recirculation of the residue so as to avoid an accumulation of polyaromatic compounds.

The method can nevertheless be implemented with recycling of part of the residue at the second stage. The recycled fraction is then mixed with the product from the first stage.

The method and its advantages will be better understood by the following examples.

Example 1

In a reactor containing an amorphous catalyst (15% Mo, 5% Ni, 80% alumina), a feed consisting of a vacuum distillate is introduced, the composition of which is given in Table I. Hydrogen is introduced under pressure of 14 MPa and in a volume ratio H₂ / HC = 1300. The space speed is then 0.5 h⁻¹.

The characteristics of the oils obtained are reported in Table 1 as a function of the temperatures.

Example 2

A 12% Mo, 4% Ni, 10% zeolite Y catalyst is loaded into a second reactor located after this first reactor on alumina.
The product from the first reactor is introduced into the second reactor.
The pressure is 14 MPa and the product circulates at a space speed of 1 h⁻¹.
The 380 ° C. residue is recovered and is then distilled under vacuum.
Table 2 makes it possible to compare the process according to the invention with a one-step process on an amorphous catalyst, for the production of high viscosity oils with high viscosity index (VI) (VI> 125) and middle distillates to from vacuum distillate.

We observe that:
. For an identical conversion (68.7%) the oil obtained with the process according to the invention has a higher viscosity (5.10⁻⁴m² / s instead of 4.5.10⁻⁴ m² / s) and is moreover obtained at significantly lower temperatures. TABLE I Charge Example 2 Example 1 Example 5 Temperatures 1st step 390 ° C 390 ° C 390 ° C 410 ° C 395 ° C 395 ° C 2nd stage 380 ° C 375 ° C 370 ° C - - 390 ° C Weight conversion 90% 80% 68.7% 68.7% 56.2% 68.7% Material balance (% weight) H2S + NH3 3.0 3.0 3.0 3.0 3.0 3.0 C1-C4 4.1 3.6 2.5 3.6 2.4 3.5 C5-150 26.9 21.8 15.7 13.5 9.6 13.0 150-380 56.0 51.6 47.5 48.7 41.2 49.2 380+ 100 12.8 22.6 33.7 33.7 46.0 33.65 Total 100 102.8 102.6 102.4 102.4 102.2 102.35 380 dewaxed residue d15 / 4 0.935 V100 ° C (m2 / s) 9.5.10⁻⁴ 3.6.10⁻⁴ 4.5.10⁻⁴ 5.0.10⁻⁴ 4.5.10⁻⁴ 5.0.10⁻⁴ 4.5.10⁻⁴ VI 50 132 133 125 134 125 133 Pour point (° C) -18 -18 -18 -18 -18 -18 -18
. The same oil base (viscosity 5.0.10⁻⁴ m² / s and VI = 125) is obtained with a production of significantly higher middle distillates in the process according to the invention (47.5% against 41.2%, or a gain of more than 15%);
. The increase in the conversion yield in the process according to the invention is not to the detriment of the viscosity of the dewaxed oil base: the yield of middle distillates can increase by 10% without the viscosity being modified.

Example 3

In a reactor containing the same catalyst as in Example 1, and under the same pressure conditions, H2 / HC and space speed, a deasphalted vacuum residue is introduced (whose viscosity at 100 ° C. is generally between 25.10⁻ ⁴ to 90.10⁻⁴ m² / s).
The characteristics of the oil bases obtained from a residue of viscosity 50 10⁻⁴ m² / s are given in Table II as a function of the temperature. The 380 ° C. residue is distilled so as to obtain the highly viscous "bright stock" oil (viscosity at 100 ° greater than or equal to 32.10⁻⁴ m² / s).

Example 4

The product from Example 3 is treated in the same way as in Example 2.
The results are presented in Table II.
Table II makes it possible to compare the process according to the invention with a one-step process on an amorphous catalyst, for the production of very viscous "brightstock" oils (viscosity ≧ 32.10⁻⁴ m² / s) and middle distillates from of deasphalted vacuum residue. TABLE II Charge Example 4 Example 3 Temperatures 1st step 390 ° C 390 ° C 390 ° C 395 ° C 410 ° C 2nd stage 370 ° C 375 ° C 380 ° C - - Weight conversion 40% 60% 80% 40% 60% Material balance (% weight) H2S + NH3 2.2 2.2 2.2 2.2 2.2 C1-C4 1.0 1.6 2.5 1.5 2.9 C5-150 9.1 18.0 33.6 6.5 12.2 150-380 27.7 38.2 41.7 29.7 42.4 380+ 100 61.5 41.8 22.2 62.0 42.3 Light oil 39.0 28.2 16.4 55.0 BS residue 22.5 13.6 5.8 7.0 Not possible Total 101.5 101.8 102.2 101.7 102.0 380 dewaxed residue d15 / 4 0.945 0.865 0.860 0.855 0.849 0.845 V100 ° C (m2 / s) 50.10⁻⁴ 13.6.10⁻⁴ 12.6.10-4 11.4.10⁻⁴ 9.8.10⁻⁴ 7.2.10⁻⁴ VI 80 114 116 118 125 136 Pour point (° C) -18 -18 -18 -18 -18 -18 BS vacuum distilled 570 ° C 575 ° C 590 ° C 700 ° C d15 / 4 0.875 0.874 0.872 0.865 V 100 ° C (m2 / s 32.10⁻⁴ 32.10⁻⁴ 32.10⁻⁴ 32.10⁻⁴ VI 108 105 106 Pour point <-18 <-18 <-18

It is observed that such oils could only be obtained with processes on an amorphous catalyst only with low conversions (<40%), since industrial distillation at 700 ° C. is practically impossible.

On the other hand, with the process according to the invention, suitable distillation temperatures (of the order of 570-590 ° C.) make it possible to obtain these very viscous oils. At the same time, the quantities of middle distillates produced are established in a wide range.

The examples above demonstrate the great flexibility of the process which is the subject of the invention which allows the operator, depending on the load and the operating conditions chosen, to obtain a wide range of oil bases accompanied by better middle distillates. .
Thus the smoke point of the kerosene obtained in Examples 2 and 4 is greater than 25 mm, while it is of the order of 20 in Examples 1 and 3.
The aromatic content of the gas oils is less than 10% in Examples 2 and 4 while it is 20% in Examples 1 and 3.

Example 5 (comparative example)

The product obtained at the end of Example 1 is passed through a second reactor containing a 15% Mo, 5% Ni and silica-alumina catalyst (48% alumina and 32% silica).
The pressure is 14 MPa and the space speed 1 h⁻¹.
The characteristics of the product obtained are given in Table I.
This test, conducted under the conditions of US Pat. No. 3,642,612 of the prior art, shows that the invention described in the present application brings new and surprising results compared to the known technique.

Claims (17)

1 ° Process for treating heavy hydrocarbon petroleum fractions with a boiling point above 380 ° C., for the improved production of middle distillates together with the production of oil bases having a viscosity index of between 95 and 150, process in which, in a first step, the section is brought into contact, in the presence of hydrogen, with at least one catalyst containing on an 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 5 and 20 MPa, the hourly space velocity being between 0.1 and 5 h⁻¹ and the quantity of hydrogen introduced such that the volume ratio hydrogen / hydrocarbons is between 150 and 2 000, said process being characterized in that the product resulting from said first stage is brought into contact in a second stage, with at least one catalyst containing a support, at least ins to the element of group VI, at least one element of group VIII and a zeolite Y, at a temperature between 350 and 430 ° C, at a pressure between 5 and 20 MPa, the hourly space velocity being between 0.1 and 5 h⁻¹, and that the product resulting from said second stage is fractionated into on the one hand the middle distillates and on the other hand the residue containing the oil bases. 2. Method according to claim 1, characterized in that the heavy cuts are chosen from the group formed by vacuum distillates, deasphalted oils, their mixtures. 3. Method according to one of the preceding claims, characterized in that the amorphous support is chosen from the group formed by alumina, silica-alumina. 4. Method according to one of the preceding claims, characterized in that the amorphous support contains at least one of the compounds chosen from the group formed by boron oxide, magnesia, zirconia, titanium oxide and clay. 5 ° Method according to one of the preceding claims, characterized in that the catalyst of the first step also contains phosphorus, in an amount of less than 15% by weight of phosphorus oxide. 6 ° Method according to one of the preceding claims, characterized in that the catalyst of the first stage contains at least one metal of GVIII chosen from nickel and cobalt, and at least one metal of GVI chosen from molybdenum and tungsten. 7 ° Method according to one of the preceding claims, characterized in that in the catalyst of the first step, the total concentration of metal oxides of groups VI and VIII is between 5 and 40% by weight and in that the ratio weight expressed as metal oxide of GVI on metal oxide of GVIII is between 20 and 1.25. 8 ° Method according to one of the preceding claims, characterized in that in the first step, the temperature is 370 to 410 ° C, the pressure from 7 to 15 MPa, the space speed from 0.3 to 1.5 h ⁻¹ and the volume ratio H hydrocar / hydrocarbons between 500 and 1500. 9 ° Method according to one of the preceding claims, characterized in that the catalyst of the second step contains at least one metal of GVIII chosen from nickel and cobalt, and at least one metal of GVI chosen from molybdenum and tungsten . 10 ° Method according to one of the preceding claims, characterized in that the catalyst of the second step also contains phosphorus. 11 ° Method according to one of the preceding claims, characterized in that the total concentration of metal oxides of the catalyst of the second step is between 1% and 40% by weight and the weight ratio expressed as metal oxide of GVI on oxide metallic content of GVIII is between 20 and 1.25. 12 ° Method according to one of the preceding claims, characterized in that, for the catalyst of the second step, the support is chosen from the group consisting of alumina, silica, silica-alumina, alumina-oxide boron, magnesia, silica-magnesia, zirconia, titanium oxide and clay, alone or in mixtures. 13 ° Method according to one of the preceding claims, characterized in that the weight content of zeolite is between 2 and 80%. 14 ° Method according to one of the preceding claims, characterized in that the zeolite is doped with metallic elements chosen from the group formed by the metals of the rare earth family, the metals of GVIII, manganese, zinc and magnesium. 15 ° Method according to one of the preceding claims, characterized in that in the second step, the temperature is between 370 and 410 ° C, the pressure between 7 and 15 MPa and the space speed between 0.3 and 1, 5 h⁻¹. 16 ° Method according to one of the preceding claims, characterized in that the catalyst of the second step contains between 3 and 25% by weight of zeolite and between 10 and 40% by weight of metal oxides of groups VIII and VI. 17 ° Method according to one of the preceding claims, characterized in that the oil base resulting from the first stage has a viscosity index between 90 and 130.