Catalyst comprising at least one zeolite NU-86, at least one zeolite USY and a porous mineral matrix and process for hydroconversion of hydrocarbon feeds using said catalyst

Abstract

The invention relates to a catalyst comprising at least one metal selected from the group formed by metals of group VIB and of group VIII of the periodic table, used alone or as a mixture, and a support comprising at least one zeolite NU-86, at least one zeolite Y and at least one porous mineral matrix containing at least aluminum and/or at least silicon. The invention also relates to a process for hydrocracking of hydrocarbon feeds employing said catalyst.

Claims

1. A catalyst comprising at least one metal of group VIB or of group VIII of the periodic table, used alone or as a mixture, and a support comprising at least one zeolite NU-86, at least one zeolite Y and at least one porous mineral matrix containing at least aluminium and/or at least silicon, said catalyst comprising, in wt % relative to the total weight of the catalyst: 0.2 to 10%, of at least one zeolite NU-86, 0.4 to 40%, of at least one zeolite Y, from 0.5 to 50% of at least one hydrogenating-dehydrogenating metal of group VIB or of group VIII, 1 to 99% of at least one porous mineral matrix comprising at least aluminium and/or at least silicon.

2. The catalyst according to claim 1 in which said zeolite Y is a dealuminized USY zeolite.

3. The catalyst according to claim 1 in which said porous mineral matrix is an alumina, doped alumina, silicalite, silica, aluminosilicate or a non-zeolitic crystalline molecular sieve, alone or as a mixture.

4. The catalyst according to claim 3 in which said porous mineral matrix is transition alumina or silica-alumina.

5. The catalyst according to claim 1 in which said catalyst comprises at least one hydrogenating-dehydrogenating metal of group VIB in combination with at least one group VIII base metal.

6. The catalyst according to claim 5 in which the content of group VIB metal, in oxide equivalent, is between 5 and 40 wt % relative to the total weight of said catalyst, and the content of group VIII base metal, in oxide equivalent, is between 0.5 and 10 wt % relative to the total weight of said catalyst.

7. A process for hydrocracking of hydrocarbon feeds, comprising contacting a hydrocarbon feed with the catalyst according to claim 1, in the presence of hydrogen, at a temperature above 200° C., at a pressure above 1 MPa, at a space velocity between 0.1 and 20 h−1 and with an amount of hydrogen introduced such that the volume ratio liter of hydrogen/liter of hydrocarbon is between 80 and 5000 L/L.

8. The process according to claim 7 in which said process is carried out at a temperature between 250 and 480° C., at a pressure between 2 and 25 MPa, at a space velocity between 0.1 and 6 h−1, and with an amount of hydrogen introduced such that the volume ratio liter of hydrogen/liter of hydrocarbon is between 100 and 2000 L/L.

9. The process according to claim 7 in which said hydrocarbon feed is at least one light gas oil from a catalytic cracking unit, atmospheric distillate, vacuum distillate, feed from units for extraction of aromatics from lubricant oil bases or from solvent dewaxing of lubricant oil bases, distillate from fixed bed or ebullating bed processes for desulphurization or hydroconversion of atmospheric residues and/or of vacuum residues and/or of deasphalted oils, paraffin from the Fischer-Tropsch process or deasphalted oil, used alone or as a mixture.

10. The process according to claim 7 in which said process is applied in a known single-step process.

11. The process according to claim 10 in which said catalyst is employed in a hydrocracking zone positioned downstream of a hydrorefining zone, without employing any intermediate separation between the two zones.

12. The process according to claim 7 in which said process is applied in a known two-step process.

13. The process according to claim 12 in which said catalyst is employed in the second step of hydrocracking positioned downstream of the first step of hydrorefining, an intermediate separation being applied between the two zones.

Description

EMBODIMENTS

(1) The hydrocracking process according to the invention employing the catalyst described above covers ranges of pressure and of conversion ranging from mild hydrocracking to high-pressure hydrocracking. Mild hydrocracking means hydrocracking that leads to moderate conversions, generally below 40%, and operating at low pressure, generally between 2 MPa and 6 MPa.

(2) The hydrocracking process according to the invention is carried out in the presence of at least one hydrocracking catalyst according to the invention. The hydrocracking process according to the invention can advantageously be performed in one or two step(s), independently of the pressure at which said process is carried out. It is carried out in the presence of one or more hydrocracking catalyst(s) obtained according to the invention, in one or more reaction unit(s) equipped with one or more reactor(s).

(3) The hydrocracking process according to the invention can advantageously employ said catalyst described above alone, in one or several fixed-bed catalyst beds, in one or more reactors, in a known single-step hydrocracking scheme, with or without liquid recycling of the unconverted fraction, optionally in conjunction with a conventional hydrotreating catalyst located upstream of the catalyst used in the process according to the present invention.

(4) The hydrocracking process according to the invention can advantageously also employ said catalyst described above alone, in one or several ebullating bed reactors, in a known single-step hydrocracking scheme, with or without liquid recycling of the unconverted fraction, optionally in conjunction with a conventional hydrotreating catalyst located in a fixed bed or ebullating bed reactor upstream of the catalyst used in the process according to the present invention.

(5) The ebullating bed operates with withdrawal of spent catalyst and daily addition of fresh catalyst in order to maintain stable catalyst activity.

(6) The catalyst described according to the invention can also advantageously be used in the first hydrotreating reaction zone, in converting pretreatment, alone or in conjunction with another conventional hydrorefining catalyst, located upstream of the catalyst described according to the invention, in one or more catalyst bed(s), in one or more fixed bed or ebullating bed reactor(s).

(7) Known Single-Step Process

(8) The hydrocracking process according to the invention can advantageously be carried out in a known single-step process.

(9) Known single-step hydrocracking comprises firstly and generally a thorough hydrorefining for the purpose of hydrodenitrogenation and a thorough desulphurization of the feed before the latter is sent to the hydrocracking catalyst proper, in particular in the case when the latter comprises a zeolite. This thorough hydrorefining of the feed only leads to limited conversion of the feed, to lighter fractions, which is still insufficient and must therefore be completed on the more active hydrocracking catalyst described above. However, it should be noted that no separation is involved between the two types of catalysts. The whole of the effluent leaving the reactor is injected onto said hydrocracking catalyst proper and it is only afterwards that separation of the products formed takes place. This version of hydrocracking, also called “once-through”, has a variant that includes recycling of the unconverted fraction to the reactor for more thorough conversion of the feed.

(10) The catalyst described according to the invention is therefore advantageously employed in a known single-step hydrocracking process, in a hydrocracking zone positioned downstream of a hydrorefining zone, without employing any intermediate separation between the two zones.

(11) Preferably, the hydrorefining catalyst used in the first hydrorefining reaction zone, alone or in conjunction with another conventional hydrorefining catalyst, located upstream of the catalyst described according to the invention, is a catalyst optionally comprising a doping element selected from phosphorus, boron and silicon, said catalyst being based on group VIII base elements and optionally in combination with group VIB elements on an alumina or silica-alumina support and even more preferably said catalyst comprises nickel and tungsten.

(12) The catalyst described according to the invention can also advantageously be used in the first hydrorefining reaction zone, in converting pretreatment, alone or in conjunction with another conventional hydrorefining catalyst, located upstream of the catalyst described according to the invention, in one or more catalyst bed(s), in one or more reactor(s).

(13) Known Single-Step Fixed Bed Process with Intermediate Separation

(14) The hydrocracking process according to the invention can advantageously be carried out in a known single-step fixed bed process with intermediate separation.

(15) Said process advantageously comprises a hydrorefining zone, a zone for partial removal of ammonia, for example by hot flash, and a zone comprising said hydrocracking catalyst according to the invention. This one-step process for hydrocracking of hydrocarbon feeds for production of middle distillates and optionally of oil bases advantageously comprises at least one first hydrorefining reaction zone, and at least one second reaction zone, in which hydrocracking of at least a proportion of the effluent from the first reaction zone is carried out. This process also advantageously comprises incomplete separation of ammonia from the effluent leaving the first zone. This separation is advantageously carried out by means of an intermediate hot flash. The hydrocracking applied in the second reaction zone is advantageously carried out in the presence of ammonia in an amount less than the amount present in the feed, preferably below 1500 ppm by weight, more preferably below 1000 ppm by weight and even more preferably below 800 ppm by weight of nitrogen.

(16) The catalyst described according to the invention is therefore employed advantageously in a known single-step fixed bed hydrocracking process with intermediate separation, in a hydrocracking zone positioned downstream of a hydrorefining zone, an intermediate separation for partial removal of ammonia being applied between the two zones.

(17) Preferably, the hydrorefining catalyst used in the first hydrorefining reaction zone, alone or in conjunction with another conventional hydrorefining catalyst, located upstream of the catalyst described according to the invention, is a catalyst optionally comprising a doping element selected from phosphorus, boron and silicon, said catalyst being based on group VIII base elements and optionally in combination with group VIB elements on an alumina or silica-alumina support and even more preferably said catalyst comprises nickel and tungsten.

(18) The catalyst described according to the invention can also advantageously be used in the first hydrorefining reaction zone, in converting pretreatment, alone or in conjunction with another conventional hydrorefining catalyst, located upstream of the catalyst described according to the invention, in one or more catalyst bed(s), in one or more reactor(s).

(19) Known Two-Step Process

(20) The hydrocracking process according to the invention can advantageously be applied in a known two-step process.

(21) Two-step hydrocracking comprises a first step with the objective, as in the “one-step” process, of performing hydrorefining of the feed, but also of reaching a conversion of the latter generally of the order of 40 to 60%. The effluent from the first step then undergoes separation (distillation), which is generally called intermediate separation, for the purpose of separating the conversion products from the unconverted fraction. In the second step of a two-step hydrocracking process, only the fraction of the feed not converted in the first step is treated. This separation enables a two-step hydrocracking process to be more selective for middle distillates (kerosene+diesel) than a single-step process. In fact, intermediate separation of the conversion products avoids their “overcracking” to naphtha and gas in the second step on the hydrocracking catalyst. Moreover, it should be noted that the unconverted fraction of the feed treated in the second step generally has very low contents of NH.sub.3 as well as of organic nitrogen compounds, generally less than 20 ppm by weight or even less than 10 ppm by weight.

(22) The configurations of fixed-bed or ebullating-bed catalyst beds described in the case of a known single-step process can advantageously be used in the first step of a known two-step scheme, whether the catalyst according to the invention is used alone or in conjunction with a conventional hydrorefining catalyst.

(23) The catalyst described according to the invention is therefore advantageously employed in a known two-step hydrocracking process, in the second step of hydrocracking positioned downstream of the first step of hydrorefining, an intermediate separation being applied between the two zones.

(24) For the known single-step processes and for the first hydrorefining step of known two-step hydrocracking processes, the conventional hydrorefining catalysts that can advantageously be used are the catalysts optionally comprising a doping element selected from phosphorus, boron and silicon, said catalyst being based on group VIII base elements and optionally in combination with group VIB elements on an alumina or silica-alumina support and even more preferably said catalyst comprises nickel and tungsten.

(25) According to a first embodiment of the hydrocracking process according to the invention, the hydrocracking catalyst(s) positioned in the hydrocracking process obtained is(are) advantageously used alone or sequentially, in one or more fixed-bed or ebullating-bed catalyst beds, in one or more reactors, in a known “one-step” hydrocracking scheme, with or without liquid recycling of the unconverted fraction, optionally in conjunction with a hydrorefining catalyst located upstream of the hydrocracking catalyst or catalysts. The ebullating bed operates with withdrawal of spent catalyst and daily addition of fresh catalyst in order to maintain stable catalyst activity.

(26) According to a second embodiment of the hydrocracking process according to the invention, the hydrocracking catalyst(s) of the hydrocracking process according to the invention is(are) advantageously used, alone or sequentially, in one or in several catalyst beds, in the one and/or other step of a known “two-step” hydrocracking scheme. The “two-step” scheme is a scheme for which there is intermediate separation of the effluents between the two reaction zones. This scheme can be carried out with or without liquid recycling of the unconverted fraction from the first reaction zone or from the second reaction zone. The first reaction zone operates with fixed bed or ebullating bed. In the particular case where the hydrocracking catalyst or catalysts obtained according to the invention are placed in the first reaction zone, they would preferably be placed in conjunction with a hydrorefining catalyst located upstream of said catalysts.

(27) The following examples illustrate the present invention but without limiting its scope.

Example 1: Preparation of a Support S1 Containing a Zeolite NU-86, a Zeolite Y and a Porous Matrix of the Silica-Alumina Type and the Corresponding Catalyst C1 (According to the Invention)

(28) One of the raw materials used is a zeolite NU-86, which is prepared according to example 2 of patent EP 0 463768 A2 and has a Si/Al overall atomic ratio equal to 11 and a Na/Al atomic ratio equal to 0.25. Another raw material used is zeolite Y in protonated form (H+) of the type CBV 720 from zéolyst (Table 1).

(29) TABLE-US-00001 TABLE 1 Description of zeolite Y Lattice Surface zeolite Ratio SiO.sub.2/Al.sub.2O.sub.3 Cationic form parameter (Å) area (m.sup.2/g) CBV720 30 H.sup.+ 24.28 780

(30) Zeolite NU-86, crude from synthesis, firstly undergoes a known dry calcining at 550° C. under a stream of dry air for 9 hours. Then the solid obtained is submitted to four ion exchanges in a 10N solution of NH.sub.4NO.sub.3, at about 100° C. for 4 hours for each exchange. The solid thus obtained is designated NH.sub.4—NU-86/1 and has a Si/Al ratio=11 and a Na/Al ratio=0.0012. Its other physicochemical characteristics are presented in Table 2.

(31) TABLE-US-00002 TABLE 2 Description of zeolite NU-86 X-ray diffraction Adsorption crystallinity .sup.SBET V(P/P.sub.O = 0.19) Sample (%) (m.sup.2/g) ml N.sub.2 liquid/g NH.sub.4-NU-86/1 100 433 0.159

(32) The crystallites of zeolite NU-86 are in the form of crystals ranging in size from 0.4 μm to 2 μm. The hydrocracking catalyst is prepared using 2 wt % of the aforementioned zeolite NU-86, which is mixed with 5.6 wt % of a zeolite Y CBV 720 mentioned above and with 92.4 wt % of a silica-alumina containing 30 wt % of SiO.sub.2 and 70 wt % of Al.sub.2O.sub.3. The mixed paste is then extruded through a die with a diameter of 1.8 mm. The extrudates are then dried overnight at 120° C. in air and then calcined at 550° C. in air. The extrudates then undergo a treatment under steam at 750° C. for 2 h.

(33) The support extrudates containing zeolite NU-86 and zeolite Y described above are impregnated dry with an aqueous solution containing ammonium metatungstate and nickel nitrate. They are dried overnight at 120° C. in air and finally calcined in air at 450° C. for 2 h. The contents by weight of oxides of catalyst C1 are 3 wt % for Ni (expressed in the form of NiO) and 28 wt % for W (expressed in the form of WO.sub.3).

Example 2: Preparation of a Support S2 Containing a Zeolite NU-86 and a Porous Matrix of the Silica-Alumina Type and the Corresponding Catalyst C2 (not According to the Invention)

(34) The same zeolite NU-86 as in example 1 was used for preparing the support S2 and the catalyst C2. The support of the hydrocracking catalyst is prepared using 7.6 wt % of the aforementioned zeolite NU-86, which is mixed with 92.4 wt % of a silica-alumina containing 30 wt % of SiO.sub.2 and 70 wt % of Al.sub.2O.sub.3. The mixed paste is then extruded through a die with a diameter of 1.8 mm. The extrudates are then dried overnight at 120° C. in air and then calcined at 550° C. in air. The extrudates then undergo a treatment under steam at 750° C. for 2 h.

(35) The support extrudates containing zeolite NU-86 are impregnated dry with an aqueous solution containing ammonium metatungstate and nickel nitrate. They are dried overnight at 120° C. in air and finally calcined in air at 450° C. for 2 h. The contents by weight of oxides of catalyst C2 are 2.9 wt % for Ni (expressed in the form of NiO) and 28.5 wt % for W (expressed in the form of WO.sub.3).

Example 3: Preparation of a Support S3 Containing a Zeolite Y and a Porous Matrix of the Silica-Alumina Type and the Corresponding Catalyst C3 (not According to the Invention)

(36) The same zeolite Y as in example 1 was used for preparing the support S3 and the catalyst C3. The support of the hydrocracking catalyst is prepared using 7.6 wt % of the aforementioned zeolite Y, which is mixed with 92.4 wt % of a silica-alumina containing 30 wt % of SiO.sub.2 and 70 wt % of Al.sub.2O.sub.3. The mixed paste is then extruded through a die with a diameter of 1.8 mm. The extrudates are then dried overnight at 120° C. in air and then calcined at 550° C. in air. The extrudates then undergo a treatment under steam at 750° C. for 2 h.

(37) The support extrudates containing zeolite Y are impregnated dry with an aqueous solution containing ammonium metatungstate and nickel nitrate. They are dried overnight at 120° C. in air and finally calcined in air at 450° C. for 2 h. The contents by weight of oxides of catalyst C3 are 3.1 wt % for Ni (expressed in the form of NiO) and 28.3 wt % for W (expressed in the form of WO.sub.3).

Example 4: Preparation of a Support S4 Containing a Zeolite Y, a Zeolite Beta and a Porous Matrix of the Silica-Alumina Type and the Corresponding Catalyst C4 (not According to the Invention

(38) The same zeolite Y as in example 1 was used for preparing the support S4 and the catalyst C4. The zeolite beta used for preparing the support S4 and the catalyst C4 is described in Table 3.

(39) TABLE-US-00003 TABLE 3 Description of zeolite beta Lattice Surface zeolite Ratio SiO.sub.2/Al.sub.2O.sub.3 Cationic form parameter (Å) area (m.sup.2/g) beta 25 H.sup.+ 26.2 680

(40) The support of the hydrocracking catalyst is prepared using 5.6 wt % of zeolite Y mentioned above, which is mixed with 2 wt % of zeolite beta mentioned above and with 92.4 wt % of a silica-alumina containing 30 wt % of SiO.sub.2 and 70 wt % of Al.sub.2O.sub.3. The mixed paste is then extruded through a die with a diameter of 1.8 mm. The extrudates are then dried overnight at 120° C. in air and then calcined at 550° C. in air. The extrudates then undergo a treatment under steam at 750° C. for 2 h.

(41) The support extrudates containing zeolite Y and zeolite beta are impregnated dry with an aqueous solution containing ammonium metatungstate and nickel nitrate. They are dried overnight at 120° C. in air and finally calcined in air at 450° C. for 2 h. The contents by weight of oxides of catalyst C4 are 3.1 wt % for Ni (expressed in the form of NiO) and 28.7 wt % for W (expressed in the form of WO.sub.3).

Example 5: Preparation of a Support S5 Containing a Zeolite NU-86, a Zeolite Y and a Porous Matrix of the Alumina Type and the Corresponding Catalyst C5 (According to the Invention)

(42) The same zeolite NU-86 in protonated form as in example 1 was used for preparing the support S5 and the catalyst C5.

(43) Another raw material used for preparing the support S5 is zeolite Y in protonated form (H+) described in Table 4.

(44) TABLE-US-00004 TABLE 4 Description of zeolite Y Lattice Surface zeolite Ratio SiO.sub.2/Al.sub.2O.sub.3 Cationic form parameter (Å) area (m.sup.2/g) USY 12 H.sup.+ 24.35 730

(45) The support of the hydrocracking catalyst is prepared using 5 wt % of the aforementioned zeolite NU-86, which is mixed with 18 wt % of a zeolite Y mentioned above and with 77 wt % of an alumina gel. The mixed paste is then extruded through a die with a diameter of 1.8 mm. The extrudates are then dried overnight at 120° C. in air and then calcined at 550° C. in air.

(46) The support extrudates containing zeolite NU-86, zeolite Y and aluminic matrix are impregnated dry with an aqueous solution, in which Ni(OH).sub.2, MoO.sub.3 and H.sub.3PO.sub.4 were dissolved beforehand. They are dried overnight at 120° C. in air and calcined at 350° C. The formulation NiMoP of catalyst C5 is 2.7-23-4.9 wt % relative to the dry weight of catalyst respectively for Ni (expressed in the form of NiO), for Mo (expressed in the form of MoO.sub.3) and for P (expressed in the form of P.sub.2O.sub.5).

Example 6: Preparation of a Support S6 Containing a Zeolite NU-86 and a Porous Matrix of the Alumina Type and the Corresponding Catalyst C6 (not According to the Invention)

(47) The same zeolite NU-86 in protonated form as in example 1 was used for preparing the support S6 and the catalyst C6.

(48) The support of the hydrocracking catalyst is prepared using 23 wt % of the aforementioned zeolite NU-86, which is mixed with 77 wt % of an alumina gel. The mixed paste is then extruded through a die with a diameter of 1.8 mm. The extrudates are then dried overnight at 120° C. in air and then calcined at 550° C. in air.

(49) The support extrudates containing zeolite NU-86 and alumina are impregnated dry with an aqueous solution, in which Ni(OH).sub.2, MoO.sub.3 and H.sub.3PO.sub.4 were dissolved beforehand. They are dried overnight at 120° C. in air and calcined at 350° C. The formulation NiMoP of catalyst C6 is 2.6-23.2-4.7 wt % relative to the dry weight of catalyst respectively for Ni (expressed in the form of NiO), for Mo (expressed in the form of MoO.sub.3) and for P (expressed in the form of P.sub.2O.sub.5).

Example 7: Preparation of a Support S7 Containing a Zeolite Y and a Porous Matrix of the Alumina Type and the Corresponding Catalyst C7 (not According to the Invention)

(50) The zeolite Y of example 7 is the same as that used in example 5.

(51) The support of the hydrocracking catalyst is prepared using 23 wt % of zeolite Y mentioned above, which is mixed with 77 wt % of an alumina gel. The mixed paste is then extruded through a die with a diameter of 1.8 mm. The extrudates are then dried overnight at 120° C. in air and then calcined at 550° C. in air.

(52) The support extrudates are impregnated dry with an aqueous solution, in which Ni(OH).sub.2, MoO.sub.3 and H.sub.3PO.sub.4 were dissolved beforehand. They are dried overnight at 120° C. in air and calcined at 350° C. The formulation NiMoP of catalyst C7 is 2.6-23.1-4.8 wt % relative to the dry weight of catalyst respectively for Ni (expressed in the form of NiO), for Mo (expressed in the form of MoO.sub.3) and for P (expressed in the form of P.sub.2O.sub.5).

Example 8: Preparation of a Support S8 Containing a Zeolite Y, a Zeolite Beta and a Porous Matrix of the Alumina Type and the Corresponding Catalyst C8 (not According to the Invention)

(53) The zeolite Y used in example 8 is the same as that used in example 5. The zeolite beta used in example 8 is the same as that used in example 4.

(54) The support of the hydrocracking catalyst is prepared using 18 wt % of zeolite Y, which is mixed with 5 wt % of zeolite beta and with 77 wt % of an alumina gel. The mixed paste is then extruded through a die with a diameter of 1.8 mm. The extrudates are then dried overnight at 120° C. in air and then calcined at 550° C. in air.

(55) The support extrudates thus prepared are impregnated dry with an aqueous solution, in which Ni(OH).sub.2, MoO.sub.3 and H.sub.3PO.sub.4 were dissolved beforehand. They are dried overnight at 120° C. in air and calcined at 350° C. The formulation NiMoP of catalyst C8 is 2.7-23.2-5 wt % relative to the dry weight of catalyst respectively for Ni (expressed in the form of NiO), for Mo (expressed in the form of MoO.sub.3) and for P (expressed in the form of P.sub.2O.sub.5).

Example 9: Evaluation of Catalysts C1, C2, C3 and C4 in High-Pressure Hydrocracking of a Vacuum Distillate

(56) The catalysts C1, C2, C3 and C4 whose preparation is described in examples 1, 2, 3 and 4 are used for carrying out hydrocracking of a partially hydrotreated vacuum distillate with the main characteristics shown in Table 5.

(57) TABLE-US-00005 TABLE 5 Characteristics of the partially hydrotreated vacuum distillate Density at 15° C. 0.9051 Sulphur (wt %) 0.24 Nitrogen (ppm by weight) 301

(58) The catalysts C1, C2, C3 and C4 were employed according to the process of the invention using a pilot unit having 1 traversed fixed bed reactor, with the fluids circulating from top to bottom (down-flow).

(59) Before the hydrocracking test, the catalysts are sulphurised at 14 MPa, at 350° C. by means of a direct-distillation gas oil with addition of 2 wt % of DMDS (dimethyl disulphide).

(60) After sulphurization, catalytic tests were carried out in the following conditions:

(61) Total pressure: 14 MPa,

(62) Hydrogen flow rate: 1000 liters of gaseous hydrogen per liter of feed injected,

(63) Space velocity (LHSV) is equal to 0.66 h.sup.−1,

(64) The temperature applied is that for which 80% of crude conversion is obtained.

(65) DMDS and aniline are added to the feed in order to maintain the H.sub.2S and NH.sub.3 partial pressures during the test that would have been generated by previous hydrotreating of the crude, non-hydrotreated feed.

(66) The catalytic performance is expressed in terms of crude conversion of the 370+ cut (molecules whose boiling point is above 370° C.) to the 370− cut (molecules whose boiling point is below 370° C.) and of crude selectivity for middle distillates (150-370° C. cut). The conversion and selectivity are expressed on the basis of the results of simulated distillation and analyses of the gases by gas chromatography.

(67) The crude conversion to products having a boiling point below 370° C., designated as CB 370° C., is taken as equal to the percentage by weight of molecules whose boiling point is below 370° C. in the effluents CB 370° C.=% of 370° C..sup.−.sub.effluents

(68) The crude selectivity for middle distillates (cut whose boiling points are between 150 and 370° C.) is designated as SB MD and is taken as equal to:
SB MD=[(fraction of 150-370.sub.effluents)]/[(% of 370° C..sup.−.sub.effluents)].

(69) The catalytic performance obtained is shown in Table 6 below.

(70) TABLE-US-00006 TABLE 6 Catalytic results for catalysts C1, C2, C3 and C4 in high-pressure hydrocracking Temperature for maintaining CB 370° C. = SB MD Catalyst Composition of the support 80% in % C1 (according to the (SiAl + 5.6% Y + 2% NU-86) 396° C. 72 invention) C2 (not according to (SiAl + 7.6% NU-86) 395° C. 64 the invention) C3 (not according to (SiAl + 7.6% Y) 401° C. 68 the invention) C4 (not according to (SiAl + 5.6% Y + 2% beta) 397.5° C. 70 the invention)

(71) The results show that the particular combination of zeolite NU-86 with zeolite Y in catalyst C1 makes it possible to generate a catalyst that is very active and highly selective for middle distillates. The presence of zeolite NU-86 only (in the case of catalyst C2 not according to the invention) makes it possible to obtain a catalyst that is very active but has extremely low selectivity for middle distillates. The addition of NU-86 in a catalyst containing zeolite Y makes it possible to increase the conversion significantly (comparison of catalysts C1 (according to the invention) and C3 (not according to the invention)) and the particular combination of the 2 zeolites makes it possible, surprisingly, to increase the selectivity for middle distillates significantly, compared to the other systems that only contain a single type of zeolite or a mixture of zeolite Y and zeolite beta (comparison of catalysts C1 (according to the invention) and C4 (not according to the invention)).

Example 10: Evaluation of Catalysts C5, C6, C7 and C8 in High-Pressure Hydrocracking of a Vacuum Distillate

(72) The catalysts C5, C6, C7 and C8 whose preparation is described in examples 5, 6, 7 and 8 are used for carrying out hydrocracking of a hydrotreated vacuum distillate with the main characteristics shown in Table 7.

(73) TABLE-US-00007 TABLE 7 Characteristics of the hydrotreated vacuum distillate Density at 15° C. 0.8659 Sulphur (ppm by weight) 54 Nitrogen (ppm by weight) 14

(74) The catalysts C5, C6, C7 and C8 were employed according to the process of the invention using a pilot unit having 1 traversed fixed bed reactor, with the fluids circulating from top to bottom (down-flow).

(75) Before the hydrocracking test, the catalysts are sulphurised at 14 MPa, at 350° C. by means of a direct-distillation gas oil with addition of 2 wt % of DMDS (dimethyl disulphide).

(76) After sulphurization, catalytic tests were carried out in the following conditions:

(77) Total pressure: 14 MPa,

(78) Hydrogen flow rate: 1000 liters of gaseous hydrogen per liter of feed injected,

(79) Space velocity (LHSV) is equal to 1 h.sup.−1,

(80) The temperature applied is that for which 70% of crude conversion is obtained.

(81) DMDS and aniline are added to the feed in order to maintain the partial pressures of H.sub.2S and NH.sub.3 during the test, that would have been generated by previous hydrotreating of the crude, non-hydrotreated feed.

(82) The catalytic performance is expressed in terms of crude conversion of the 370+ cut (molecules whose boiling point is above 370° C.) to the 370− cut (molecules whose boiling point is below 370° C.) and of the yield of middle distillates (MD, 150-370° C. cut). The conversion and the yield of MD are expressed on the basis of the results of simulated distillation and analyses of the gases by gas chromatography.

(83) The crude conversion to products having a boiling point below 370° C., designated as CB 370° C., is taken as equal to the percentage by weight of molecules whose boiling point is below 370° C. in effluents CB 370° C.=% of 370° C..sup.−.sub.effluents

(84) The yield of middle distillates (cut whose boiling points are between 150 and 370° C.) is taken as equal to:

(85) Yield of MD=% of molecules whose boiling points are between 150° C. and 370° C. in the effluents.

(86) The catalytic performance obtained is shown in Table 8 below.

(87) TABLE-US-00008 TABLE 8 Catalytic results for C5, C6, C7 and C8 in high-pressure hydrocracking Temperature for maintaining CB 370° C. = Yield of MD Catalyst Composition of the support 80% in % C5 (according to the (alumina + 18% Y + 5% NU-86) 368.5 55.4 invention) C6 (not according to (alumina + 23% NU-86) 367.5 49.7 the invention) C7 (not according to (alumina + 23% Y) 370 52.6 the invention) C8 (not according to (alumina + 18% Y + 5% beta) 369 54 the invention)

(88) The results show that the particular combination of zeolite NU-86 with zeolite Y in catalyst C5 makes it possible to generate a catalyst that is very active and highly selective for middle distillates. The presence of zeolite NU-86 only (in the case of catalyst C6 not according to the invention) makes it possible to obtain a catalyst that is very active but has extremely low selectivity for middle distillates. The addition of NU-86 in a catalyst containing zeolite Y makes it possible to increase the conversion significantly (comparison of catalysts C5 (according to the invention) and C7 (not according to the invention)) and the particular combination of 2 zeolites makes it possible, surprisingly, to increase the selectivity for middle distillates significantly, compared to the other systems that only contain a single type of zeolite or a mixture of zeolite Y and zeolite beta (comparison of catalysts C5 (according to the invention) and C8 (not according to the invention)).