FR2951190A1 - METHOD FOR HYDROTREATING AND HYDROISOMERIZING RENEWABLE SOURCE CHARGES USING MODIFIED ZEOLITHE - Google Patents

Abstract

The present invention describes a process for the treatment of charges originating from a renewable source using a catalyst comprising at least one hydro-dehydrogenating metal chosen from the group formed by the metals of group VIB and group VIII of the periodic table and a support comprising at least one zeolite having at least one series of channels whose opening is defined by an 8-atom oxygen ring modified by a) at least one step of introducing at least one alkaline cation belonging to groups IA or IIA of the periodic table, b) a step of treating said zeolite in the presence of at least one molecular compound containing at least one silicon atom, c) at least one step of partial exchange of said alkaline cations with NH and d cations. ) at least one heat treatment step.

Description

FIELD OF THE INVENTION In an international context marked by the rapid growth in the need for fuels, in particular diesel and kerosene bases in the European community, the search for new renewable energy sources that can be integrated into the traditional scheme of refining and the production of fuels is a major issue.

As such, the integration into the refining process of new products of plant origin, resulting from the conversion of lignocellulosic biomass or from the production of vegetable oils or animal fats, has in recent years experienced a very lively renewed interest due to the rising cost of fossil fuels. Similarly, traditional biofuels (mainly ethanol or methyl esters of vegetable oils) have acquired a real status of supplementing petroleum fuels in fuel pools. In addition, the processes known to date using vegetable oils or animal fats are responsible for CO2 emissions, known for these negative effects on the environment. A better use of these bio-resources, such as for example their integration in the fuel pool would therefore be a definite advantage.

The strong demand for diesel fuels and kerosene, coupled with the importance of environmental concerns, reinforces the interest of using renewable sources. These fillers include for example vegetable oils, animal fats, raw or having undergone prior treatment, as well as mixtures of such fillers. These fillers contain chemical structures of the triglyceride or ester or fatty acid type, the structure and the hydrocarbon chain length of the latter being compatible with the hydrocarbons present in gas oils and kerosene.

One possible route is the catalytic conversion of the renewable source feedstock into deoxygenated paraffinic fuel in the presence of hydrogen (hydrotreatment). Many metal catalysts or sulfides are known to be active for this type of reaction.

These hydrotreatment processes from renewable source are already well known and are described in many patents. For example, the patents are US Pat. No. 4,992,605, US Pat. No. 5,705,722, EP 1,681,337 and EP 1,741,768. The use of transition metal sulphide solids allows the production of paraffins from ester-type molecules in two reaction ways: The hydrodeoxygenation leading to the formation of water by hydrogen consumption and the formation of number of carbon (Cn) hydrocarbons equal to that of the initial fatty acid chains, decarboxylation / decarbonylation leading to the formation of carbon oxides (carbon monoxide and dioxide: CO and CO2) and the formation of hydrocarbons with one less carbon (Cn-1) than the initial fatty acid chains.

The liquid effluent resulting from these hydrotreatment processes consists essentially of n-paraffins which can be incorporated into the diesel fuel and kerosene pool. In order to improve the cold properties of this hydrotreated liquid effluent, a hydroisomerization step is necessary to convert n-paraffins into branched paraffins having better properties when cold.

For example, patent application EP 1 741 768 describes a process comprising a hydrotreatment followed by a hydroisomerization step in order to improve the cold properties of the linear paraffins obtained. The catalysts used in the hydroisomerization step are bifunctional catalysts consist of a metal active phase comprising a Group VIII metal selected from palladium, platinum and nickel, dispersed on a molecular sieve type acid support selected from SAPO-11, SAPO-41, ZSM-22, ferrierite or ZSM-23, said process operating at a temperature between 200 and 500 ° C, and at a pressure of between 2 and 15 MPa. Nevertheless, the use of this type of solid results in a loss of average distillate yield.

The research work carried out by the applicant on the modification of numerous crystallized microporous zeolites and solids and on the hydrogenating active phases led him to discover that, surprisingly, a catalyst for the hydroisomerization of paraffinic hydrocarbon feedstocks and in particular the hydrotreatment of feeds from a renewable source, comprising an active phase containing at least one hydro-dehydrogenating element chosen from Group VIB and Group VIII elements and a support comprising at least one zeolite having at least one series of channels of which the aperture is defined by an 8-atom oxygen ring, said zeolite being modified by a particular modification process to obtain a higher activity, ie a higher conversion level, while allowing to obtain a yield of middle distillates (improved jet fuels and gas oils), the hydro step isomerization being implemented in a process for treating feedstock from a renewable source comprising upstream of said hydroisomerization step, a hydrotreating step.

The modification of zeolite by deposition of compounds containing at least one molecular compound containing at least one silicon atom has been widely studied in the past. In addition, mention may be made of US Pat. No. 4,402,867, which describes a method for preparing a zeolite-based catalyst comprising a step of depositing at least 0.3% by weight of amorphous silica in the aqueous pores in the aqueous phase. the zeolite. US Pat. No. 4,996,034 describes a process for substitution of aluminum atoms present in a zeolitic framework with silicon atoms, said process being carried out in one step in an aqueous medium using fluorosilicate salts. US Pat. No. 4,451,572 describes the preparation of a zeolite catalyst comprising a step of depositing organosilicic materials in the vapor or liquid phase, the targeted zeolites being large-pore zeolites, in particular zeolite Y. An objective of the invention is therefore to provide a process for the treatment of charges from a renewable source which, in a hydroisomerisation step, downstream of a hydrotreatment stage, a hydroisomerization catalyst comprising a modified zeolite-based support making it possible to obtain high yields of diesel and kerosene bases. Another object of the invention is to provide a process for the treatment of feeds from a renewable source which, in a hydroisomerisation step, downstream of a hydrotreatment step, comprises a catalyst comprising as a support a modified zeolite allowing to minimize the production of light fraction 150 ° C-. OBJECT OF THE INVENTION More specifically, the invention relates to a process for the treatment of charges originating from a renewable source comprising the following stages: a) hydrotreatment in the presence of a catalyst in a fixed bed, at a temperature of between 200 and 450 ° C. at a pressure of between 1 MPa and 10 MPa, at a space velocity of between 0.1 h -1 and 10 h -1 and in the presence of a total amount of hydrogen mixed with the feed such as the hydrogen ratio charge / is between 70 and 1000 Nm3 of hydrogen / m 3 of feed, b) separation from the effluent from step a) of hydrogen, gases and at least one hydrocarbon base, c ) hydroisomerization of at least a portion of said hydrocarbon base from step b) in the presence of a fixed bed hydroisomerization catalyst, said catalyst comprising at least one hydro-dehydrogenating metal selected from the group consisting of metals of Group VIB and Group VIII of Commission periodicalassassification, alone or as a mixture, and a support comprising at least one zeolite having at least one series of channels whose opening is defined by an 8-atom oxygen ring, modified by a ') at least one step of introduction of at least one alkaline cation belonging to groups IA or IIA of the periodic classification, b ') a step of treating said zeolite in the presence of at least one molecular compound containing at least one silicon atom, c') to at least one step of partial exchange of said alkaline cations with NH 4 + cations and at least one heat treatment step, said hydroisomerization step being carried out at a temperature between 150 and 500 ° C, at a pressure of between 1 MPa and 10 MPa, at a space velocity of between 0.1 and 10 h -1 and in the presence of a total amount of hydrogen mixed with the feed such that the hydrogen / feed ratio is between 70 and 1000 Nm 3 / m3 of charge, d) separation, from the effluent from step c) of hydrogen, gases and at least one diesel base and a kerosene base.

DETAILED DESCRIPTION OF THE INVENTION The present invention is particularly dedicated to the preparation of gas oil and kerosene fuel bases corresponding to the new environmental standards, from charges derived from renewable sources.

The feedstocks derived from renewable sources used in the present invention are advantageously chosen from oils and fats of vegetable or animal origin, or mixtures of such fillers, containing triglycerides and / or free fatty acids and / or esters. Vegetable oils can advantageously be crude or refined, wholly or in part, and derived from the following plants: rapeseed, sunflower, soybean, palm, palm kernel, olive, coconut, jatropha, this list not being limiting. Algae or fish oils are also relevant. Animal fats are advantageously chosen from lard or fats composed of residues from the food industry or from the catering industries. These fillers essentially contain chemical structures of the triglyceride type which the skilled person also knows under the name tri ester of fatty acids as well as free fatty acids. A fatty acid ester tri is thus composed of three chains of fatty acids. These fatty acid chains in the form of tri-ester or in the form of free fatty acid have a number of unsaturations per chain, also called number of carbon-carbon double bonds per chain, generally between 0 and 3 but which can be higher especially for oils derived from algae which generally have a number of unsaturations in chains of 5 to 6. The molecules present in the feeds from renewable sources used in the present invention therefore have a number of unsaturations, expressed by triglyceride molecule, advantageously between 0 and 18. In these fillers, the unsaturation level, expressed as number of unsaturations per hydrocarbonaceous fatty chain, is advantageously between 0 and 6. Charges from renewable sources generally include also different impurities and especially heteroatoms such as nitrogen. Nitrogen levels in vegetable oils are generally between about 1 ppm and about 100 ppm by weight, depending on their nature. They can reach up to 1% weight on particular loads. Advantageously, the feedstock may undergo before step a) of the process according to the invention a pre-treatment or pre-refining step so as to eliminate, by appropriate treatment, contaminants such as metals, such as alkaline compounds for example on ion exchange resins, alkaline earths and phosphorus. Suitable treatments may for example be heat and / or chemical treatments well known to those skilled in the art.

According to step a) of the process according to the invention, the charge, possibly pretreated, is brought into contact with a catalyst in a fixed bed at a temperature of between 200 and 450 ° C., preferably between 220 and 350 ° C. preferably between 220 and 320 ° C, and even more preferably between 220 and 310 ° C. The pressure is between 1 MPa and 10 MPa, preferably between 1 MPa and 6 MPa and even more preferably between 1 MPa and 4 MPa. The hourly space velocity is between 0.1 hr-1 and 10 hr-1. The filler is contacted with the catalyst in the presence of hydrogen. The total quantity of hydrogen mixed with the feedstock is such that the hydrogen / feedstock ratio is between 70 and 1000 Nm3 of hydrogen / m.sup.3 of feedstock and preferably between 150 and 750 Nm.sup.3 of hydrogen / m.sup.3 of feedstock. In step a) of the process according to the invention, the fixed-bed catalyst is advantageously a hydrotreatment catalyst comprising a hydro-dehydrogenating function comprising at least one Group VIII and / or Group VIB metal, taken alone or in a mixture and a support selected from the group consisting of alumina, silica, silica-aluminas, magnesia, clays and mixtures of at least two of these minerals. This support may also advantageously contain other compounds and for example oxides selected from the group formed by boron oxide, zirconia, titanium oxide, phosphoric anhydride. The preferred support is an alumina support and very preferably alumina 11, S or y.

Said catalyst is advantageously a catalyst comprising metals of the group VIII preferably chosen from nickel and cobalt, taken alone or as a mixture, preferably in combination with at least one metal of group VIB, preferably chosen from molybdenum and tungsten, taken alone or mixed.

The content of metal oxides of groups VIII and preferably of nickel oxide is advantageously between 0.5 and 10% by weight of nickel oxide (NiO) and preferably between 1 and 5% by weight of oxide of nickel. nickel and the content of metal oxides of groups VIB and preferably molybdenum trioxide is advantageously between 1 and 30% by weight of molybdenum oxide (MoO3), preferably from 5 to 25% by weight, the percentages being expressed in% by weight relative to the total mass of the catalyst.

The total content of metal oxides of groups VIB and VIII in the catalyst used in step a) is advantageously between 5 and 40% by weight and preferably between 6 and 30% by weight relative to the total mass. catalyst.

The weight ratio expressed as metal oxide between metal (or metals) of group VIB on metal (or metals) of group VIII is advantageously between 20 and 1 and preferably between 10 and 2.

Said catalyst used in step a) of the process according to the invention must advantageously be characterized by a high hydrogenating power so as to orient as much as possible the selectivity of the reaction towards a hydrogenation preserving the number of carbon atoms of the fatty chains. that is to say the hydrodeoxygenation route, this in order to maximize the yield of hydrocarbons entering the field of distillation of kerosenes and / or gas oils. This is why, preferably, one operates at a relatively low temperature. Maximizing the hydrogenating function also makes it possible to limit the polymerization and / or condensation reactions leading to the formation of coke which would degrade the stability of the catalytic performances. Preferably, a Ni or NiMo type catalyst is used.

Said catalyst used in step a) of hydrotreating of the process according to the invention may also advantageously contain a doping element chosen from phosphorus and boron, taken alone or as a mixture. Said doping element may be introduced into the matrix or preferably deposited on the support. It is also possible to deposit silicon on the support, alone or with phosphorus and / or boron and / or fluorine. The oxide weight content of said doping element is advantageously less than 20% and preferably less than 10% and is advantageously at least 0.001%. The metals of the catalysts used in step a) of hydrotreatment of the process according to the invention are sulphide metals or metal phases and preferably sulphurized metals.

It is not within the scope of the present invention to use in step a) of the process according to the invention, simultaneously or successively, a single catalyst or several different catalysts. This step can be carried out industrially in one or more reactors with one or more catalytic beds and preferably downflow of liquid. According to step b) of the process according to the invention, the hydrotreated effluent from atep a) is subjected at least in part, and preferably entirely, to one or more separations. The purpose of this step is to separate the gases from the liquid, and in particular to recover the hydrogen-rich gases which may also contain gases such as CO and CO2 and at least one liquid hydrocarbon base with a sulfur content of less than 10 ppm by weight. . The separation is carried out according to all methods of separation known to those skilled in the art. The separation step may advantageously be carried out by any method known to those skilled in the art such as, for example, the combination of one or more high and / or low pressure separators, and / or distillation and / or distillation stages. high and / or low pressure stripping.

The water that may be formed during step a) of hydrotreatment of the process according to the invention may also be advantageously separated at least in part from the liquid hydrocarbon base. The separation step b) may therefore advantageously be followed by an optional step of removing at least a portion of the water and preferably all of the water. The purpose of the optional water removal step is to remove at least a portion of the water produced during the hydrotreatment reactions. The elimination of water is the elimination of the water produced by the hydrodeoxygenation (HDO) reactions. The more or less complete elimination of water may be a function of the water tolerance of the hydroisomerization catalyst used in the subsequent step c) of the process according to the invention. The removal of water can be carried out by all the methods and techniques known to those skilled in the art, for example by drying, passage on a desiccant, flash, decantation ....

According to step c) of the process according to the invention, at least part, and preferably all, of the liquid hydrocarbon base obtained at the end of step b) of the process according to the invention is hydroisomerized in the presence of a fixed-bed hydroisomerization catalyst, said catalyst comprising at least one hydrodehydrogenating metal selected from the group consisting of Group VIB metals and Group VIII of the Periodic Table, taken alone or as a mixture and a support comprising at least one zeolite having at least one series of channels whose openings is defined by an 8-atom oxygen ring, said zeolite being modified according to a particular method.

The hydrogenating phase According to the invention, the catalyst used in the hydroisomerization step c) of the process according to the invention comprises at least one hydrodehydrogenating metal chosen from the group consisting of Group VIII metals and group VIB, alone or in combination. Preferably, the elements of group VIII are chosen from iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium or platinum, taken alone or as a mixture. where the elements of group VIII are selected from noble metals of group VIII, the elements of group VIII are advantageously chosen from platinum and palladium, taken alone or as a mixture. In the case where the elements of group VIII are selected from non-noble metals of group VIII, the elements of group VIII are advantageously chosen from iron, cobalt and nickel, taken alone or as a mixture.

Preferably, the group VIB elements of the catalyst according to the present invention are selected from tungsten and molybdenum.

In the case where the catalyst comprises at least one Group VIB metal in combination with at least one Group VIII non-noble metal, the Group VIB metal content is advantageously comprised, in oxide equivalent, of between 5 and 40% by weight per relative to the total mass of said catalyst, preferably between 10 and 35% by weight and very preferably between 15 and 30% by weight and the non-noble metal content of group VIII is advantageously comprised, in oxide equivalent, between 0 , 5 and 10% by weight relative to the total mass of said catalyst, preferably between 1 and 8% by weight and very preferably between 1.5 and 6% by weight. In the case where said catalyst comprises at least one Group VIB metal in combination with at least one Group VIII non-noble metal, said catalyst may also advantageously comprise at least one doping element selected from the group consisting of silicon, boron and phosphorus, taken alone or as a mixture, the content of doping element being preferably between 0 and 20% by weight of oxide of the doping element, preferably between 0.1 and 15% by weight, very preferably preferred between 0.1 and 10% by weight very preferably between 0.5 and 6% by weight relative to the total mass of the catalyst. In the case where the hydrogenating function comprises a group VIII element and a group VIB element, the following metal combinations are preferred: nickel-molybdenum, cobalt-molybdenum, nickel-tungsten, cobalt-tungsten, and very preferably: nickel-molybdenum, cobalt-molybdenum, nickel-tungsten. It is also possible to use combinations of three metals such as, for example, nickel-cobalt-molybdenum. When a combination of Group VI and Group VIII metals is used, the catalyst is then preferably used in a sulfurized form. When the hydro-dehydrogenating element is a Group VIII noble metal, the catalyst preferably contains a preferred content. noble metal of between 0.01 and 10% by weight, even more preferably from 0.02 to 5% by weight relative to the total weight of said catalyst. The noble metal is preferably used in its reduced and non-sulphurized form.

It is also advantageously possible to employ a reduced, non-sulfurized nickel-based catalyst. In this case the metal content in its oxide form is advantageously between 0.5 and 25% by weight relative to the finished catalyst. Preferably, the catalyst also contains, in addition to the reduced nickel, a group IB metal and preferably copper, or a group IVB metal and preferably tin in proportions such that the mass ratio of the group metal IB or IVB and nickel on the catalyst is advantageously between 0.03 and 1.

Said hydroisomerization catalyst used in stage c) of the process according to the invention comprises a support comprising at least one modified zeolite and advantageously a porous oxide matrix of oxide type, said support comprising and preferably consisting of, preferably: 0.1 to 99.8% by weight, preferably 0.1 to 80% by weight, even more preferably 0.1 to 70% by weight, and very preferably 0.1 to 50% by weight, weight of zeolite modified according to the invention relative to the total mass of the catalyst, 0.2 to 99.9% by weight, preferably from 20 to 99.9%, preferably from 30 to 99.9% by weight, and very preferably from 50 to 99.9% by weight, based on the total weight of the catalyst, of at least one oxide-type porous mineral matrix.

According to the invention, the zeolite contained in the catalyst support used in stage c) of the process according to the invention comprises at least one series of channels whose opening is defined by a ring to 8 oxygen atoms (8MR) before being modified. Said zeolite is chosen from zeolites defined in the "Atlas of Zeolite Structure Types" classification, Ch. Baerlocher, LB McCusker, DH Oison, Heme Edition, Elsevier, 2007, Elsevier "exhibiting at least one series of channels whose opening In a particular embodiment, the zeolite initially used before being modified may advantageously contain, in addition to at least one series of channels, of which 35 aperture is defined by a ring of 8 oxygen atoms (8MR), at least one series of channels whose pore opening is defined by a ring containing 10 oxygen atoms (10 MR) and / or at least one series of channels whose pore opening is defined by a ring containing 12 oxygen atoms (12 MR).

The zeolite may advantageously contain at least one other element T, different from silicon and aluminum, integrating in tetrahedral form into the framework of the zeolite. Preferably, said element T is chosen from iron, germanium, boron and titanium and represents a portion by weight of between 2 and 30% of all the constituent atoms of the zeolitic framework other than the oxygen atoms. The zeolite then has an atomic ratio (Si + T) / Al of between 2 and 200, preferably of between 3 and 100 and very preferably of between 4 and 80, T being defined as above. Preferably, the zeolite contained in the support of the catalyst used in stage c) of the process according to the invention is chosen from zeolites Y, ZSM-48, ZBM-30, IZM-1 and COK-7, taken alone or in mixture. Preferably, the zeolite is chosen from zeolites Y, ZSM-48, ZBM-30, IZM-1 and COK-7, taken alone or as a mixture. Very preferably, said zeolite is chosen from zeolites Y, ZSM-48 and ZBM-30, the ZBM 30 being preferably synthesized with the organic structuring agent triethylenetetramine, taken alone or as a mixture.

Zeolite ZBM-30 is described in patent EP-A-46 504, and zeolite COK-7 is described in patent applications EP 1 702 888 A1 or FR 2 882 744 A1. Zeolite IZM-1 is described in US Pat. FR-A-2,911,866 and zeolite ZSM 48 are described in Schlenker, JL Rohrbaugh, WJ, Chu, P., Valyocsik, EW and Kokotailo, GT Title: The high-level framewrok of ZSM-48: a high The zeolite initially used is a FAU zeolite having a three-dimensional network of channels whose opening is defined by 12 oxygen atoms (12 MR) and even more preferably, the initial zeolite is zeolite Y.

Preferably, said zeolite may advantageously be dealuminated in all the ways known to those skilled in the art, so that the atomic ratio of silicon to aluminum of the zeolite is between 2.5 and 200, preferably between 3 and 200. and 100 and even more preferably between 4 and 80. The atomic ratio of silicon to aluminum Si / Al framework of the zeolite is measured by NMR of silicon and aluminum according to a method known to those skilled in the art. The structural type zeolite FAU having undergone one or more dealumination steps which has a three-dimensional network of channels whose opening is defined by a ring with 12 oxygen atoms (12 MR) is suitable for the use of the catalyst used in the process according to the invention. Preferably, the zeolite initially used is a dealuminated FAU zeolite and very preferably, the initial zeolite is the dealuminated Y zeolite; Process for modifying the zeolite contained in the catalyst support used in the process according to the invention. According to the invention, the zeolite contained in the catalyst support used in stage c) of the process according to the invention, initially having, before being modified, at least one series of channels whose opening is defined by an 8-atom oxygen ring (8MR) is modified by a ') a step of introducing at least one alkaline cation belonging to groups IA or IIA of the periodic table, b') a treatment step of said zeolite in the presence of at least one molecular compound containing at least one silicon atom, c ') at least partial exchange of the alkaline cations with NH 4 + cations and d) at least one heat treatment step.

Said initial zeolite is thus modified according to a modification process comprising at least one step a) of introduction of at least one alkaline cation belonging to groups IA and IIA of the periodic table of the elements, said cation (s) (s) being preferably chosen from Na +, Li +, K +, Rb +, Cs +, Bat + and Cal + cations and very preferably, said cation being the Na + cation. This step can be carried out by any method known to those skilled in the art and preferably this step is performed by the so-called ion exchange method. At the end of step a ') of the modification process, the zeolite contained in the catalyst support used in step c) of the process according to the invention is in cationic form.

The process for modifying said zeolite then comprises a treatment step b ') in the presence of at least one molecular compound containing at least one silicon atom. This step is called the step of selectivation of said zeolite. For the purposes of the present invention, the term "selectivation" means the neutralization of the acidity of each of the crystals of the cationic zeolite. The neutralization of the acidity can be done by any method known to those skilled in the art. Conventional methods generally employ molecular compounds containing atoms that can interact with the zeolite crystal sites. The molecular compounds used in the context of the invention are organic or inorganic molecular compounds containing one or more silicon atom (s).

Also, according to step b ') of treatment, the cationic zeolite prepared according to step a'), is subjected to a treatment step in the presence of at least one molecular compound containing at least one silicon atom. Said step b ') allows the deposition of a layer of said molecular compound containing at least one silicon atom on the surface of the crystals of the zeolite which will be transformed after step c') into an amorphous silica layer on the surface of each of the crystals of the zeolite. Preferably, the molecular compound containing at least one silicon atom is chosen from the compounds of formula Si-R 4 and Si 2 -R 6 where R is chosen from hydrogen, an alkyl, aryl, acyl group, an alkoxy group (O- R '), a hydroxyl (-OH) group or a halogen, and preferably an alkoxy group (O-R'). Within the same molecule Si-R4 or Si2-R6, the group R may advantageously be either identical or different. Preferably, the molecular compound is chosen from compounds of formula Si 2 H 6 or Si (C 2 H 5) 3 (CH 3). Thus, the molecular compound containing at least one silicon atom used in step b) of the process according to the invention may advantageously be a compound of silane, disilane, alkylsilane, alkoxysilane or siloxane type. Said molecular compound used for the implementation of step b ') according to the invention preferably comprises at most two silicon atoms per molecule. Very preferably, said molecular compound has a composition of general formula Si- (OR ') 4 where R' is an alkyl, aryl or acyl group, preferably an alkyl group and very preferably an ethyl group. Very preferably, the molecular compound containing at least one silicon atom is the tetraethylorthosilicate (TEOS) molecular compound of formula Si (OCH 2 CH 3) 4.

Said step b ') of the modification process which consists in treating the cationic zeolite exchanged according to step a') in the presence of at least one molecular compound containing at least one silicon atom, is advantageously carried out by depositing said compound on the internal and external surfaces of the zeolite. It is possible to carry out a gas phase deposition known as CVD ("Chemical Vapor Deposition") or a liquid phase deposit called CLD ("Chemical Liquid Deposition") by any method known to those skilled in the art. Preferably, said step b ') is carried out by depositing said molecular compound containing at least one silicon atom in the liquid phase.

If step b ') of the modification process is carried out by gas phase deposition (CVD), it is advantageously carried out in a fixed bed reactor. Prior to the gas phase deposition (CVD) reaction in said fixed bed reactor, the zeolite is preferably activated. Activation of the zeolite in the fixed bed reactor is carried out under oxygen, in air or under an inert gas, or in a mixture of air and inert gas or oxygen and inert gas. The activation temperature of the zeolite is advantageously between 100 and 600 ° C, and very advantageously between 300 and 550 ° C. The molecular compound containing at least one silicon atom to be deposited on the outer surface of each of the crystals of the zeolite is sent to the vapor phase reactor, said molecular compound being diluted in a carrier gas which can be either hydrogen (H2 ), or air, Argon (Ar), helium (He), or even nitrogen (N2), preferably the carrier gas is an inert gas selected from Ar, He, and N2. Said molecular compound containing at least one silicon atom is deposited on the outer surface of said zeolite in the vapor phase. In order to obtain an optimum quality layer of amorphous silica on the external surface of the zeolite at the end of step c '), it is necessary to choose the operating conditions for deposition of the molecular compound containing at least one atom. silicon. In particular, the temperature of the zeolite bed during the deposition is preferably between 10 and 300 ° C., and very preferably between 50 and 200 ° C., the partial pressure, in the gas phase, of the molecular compound to be deposited on the surface. external of the zeolite is preferably between 0.001 and 0.5 bar, and very preferably between 0.01 and 0.2 bar, the duration of the deposit is preferably between 10 minutes and 10 hours and very preferably between 30 minutes and 5 hours and even more preferably between 1 and 3 hours.

If step b ') of the modification process is carried out by liquid phase deposition (CLD), it is advantageously carried out with stirring. A CLD phase deposition can be done either in aqueous medium or in an organic solvent. During the aqueous impregnation of the molecular compound containing at least one silicon atom, one or more surfactants may or may not be added to the impregnating solution. CLD deposition is well known to those skilled in the art (Chon et al., Studies in Surface Science and Catalysis, 105, 2059-2065, 1997). Preferably, said molecular compound containing at least one silicon atom is deposited on the outer surface of said zeolite in an anhydrous organic solvent. The organic solvent is advantageously chosen from saturated or unsaturated molecules containing from 5 to 10 carbon atoms, and preferably from 6 to 8 carbon atoms. In order to obtain an optimum quality layer of amorphous silica on the external surface of the zeolite at the end of step c '), it is necessary to choose the operating conditions for deposition of the molecular compound containing at least one atom. silicon.

In particular, the temperature of the organic solvent solution is preferably between 10 and 100 ° C, and very preferably between 30 and 90 ° C. The amount of silica added to the anhydrous solvent solution is advantageously between 0.0001 and 5% by weight, preferably between 0.0001 and 2% by weight, and even more preferably between 0.0005 and 1% by weight relative to to the amount of zeolite. The duration of the deposition is preferably between 5 minutes and 10 hours, preferably between 30 minutes and 5 hours and even more preferably between 1 and 3 hours.

The process for modifying the zeolite then comprises a step c ') corresponding to at least a partial exchange of the alkaline cations belonging to groups IA and IIA of the periodic table introduced during step a') and preferably Na + cations by NH4 cations. By partial exchange of the alkali cations and preferably Na + cations, NH4 + cations, the exchange of 80 to 99%, preferably 85 to 98% and more preferably 90 to 98% of the alkaline cations. and preferably Na + cations by NH4 + cations. The amount of alkaline cations remaining and preferably, the amount of Na + cations remaining in the modified zeolite, relative to the amount of NH 4 + cations initially present in the zeolite, is advantageously between 1 and 20%, preferably between 1.5 and 20% preferably, between 2 and 15% and more preferably between 2 and 10%. Preferably, for this step, several ion exchange (s) are carried out with a solution containing at least one ammonium salt chosen from chlorate salts, sulfate, nitrate, phosphate, or ammonium acetate, so to eliminate at least in part, the alkaline cations and preferably the Na + cations present in the zeolite. Preferably, the ammonium salt is ammonium nitrate NH4NO3. Thus, preferably, the content of alkaline cations remaining and preferably Na + cations in the zeolite modified at the end of step c ') is preferably such that the molar ratio alkali metal cation / aluminum and preferably the molar ratio Na / Al is between 0.2: 1 and 0.01: 1, preferably between 0.2: 1 and 0.015: 1, more preferably between 0.15: 1 and 0.02: 1. and even more preferably between 0.1: 1 and 0.02: 1. The desired Na / Al ratio is obtained by adjusting the NH 4 + concentration of the cation exchange solution, the cation exchange temperature, and the cation exchange number. The concentration of the NH 4 + solution in the solution advantageously varies between 0.01 and 12 mol / l, and preferably between 1 and 10 mol / l. The temperature of the exchange step is advantageously between 20 and 100 ° C, preferably between 60 and 95 ° C, preferably between 60 and 90 ° C, more preferably between 60 and 85 ° C and even more preferred between 60 and 80 ° C. The cation exchange number advantageously varies between 1 and 10 and preferably between 1 and 4.

Maintaining a controlled content of alkaline cations and preferably Na + cations in place of protons neutralizes the more acidic Bronsted and Lewis sites of the zeolite, thereby decreasing the secondary cracking of the middle distillate molecules. gasoline during hydrocracking reactions. This effect makes it possible to obtain a gain in selectivity for middle distillates. If the amount of the alkaline cations and preferably the remaining Na + cations in the structure of the modified zeolite is too large, the number of Bronsted acid sites decreases too much, resulting in a loss of catalyst activity.

The process for modifying the zeolite then comprises at least one step d) of heat treatment. This heat treatment allows both the decomposition of the molecular compound containing at least one silicon atom deposited on the zeolite at the end of step b ') and the transformation of the NH 4 cations, partially exchanged at the end of the step c '), in protons. The heat treatment according to the invention is carried out at a temperature preferably between 200 and 700 ° C, more preferably between 300 and 500 ° C. Said heat treatment step is advantageously carried out under air, under oxygen, under hydrogen, under nitrogen or under argon or under a mixture of nitrogen and argon. The duration of this treatment is advantageously between 1 and 5 hours. At the end of said heat treatment step), an amorphous silica layer is deposited on the surface of each of the crystals of the zeolite and the protons of the zeolite are partially regenerated.

The amorphous or poorly crystallized porous mineral matrix of the oxide type The support of the hydroisomerization catalyst used in stage c) of the process according to the invention advantageously contains a porous mineral matrix, preferably amorphous, which advantageously consists of at least a refractory oxide. Said matrix is advantageously chosen from the group formed by alumina, silica, clays, titanium oxide, boron oxide and zirconia. The matrix may consist of a mixture of at least two of the oxides mentioned above, and preferably silica-alumina. It is also possible to choose aluminates. It is preferred to use matrices containing alumina, in all these forms known to those skilled in the art, for example gamma-alumina. It is also advantageous to use mixtures of alumina and silica, mixtures of alumina and silica-alumina.

Preparation of the catalyst The modified zeolite may be, without limitation, for example in the form of powder, ground powder, suspension, suspension having undergone a deagglomeration treatment. Thus, for example, the modified zeolite may advantageously be slurried acidulated or not at a concentration adjusted to the final zeolite content referred to the support. This suspension commonly called a slip is then advantageously mixed with the precursors of the matrix.

According to a preferred method of preparation, the modified zeolite can advantageously be introduced during the shaping of the support with the elements that constitute the matrix. For example, according to this preferred embodiment of the present invention, the modified zeolite according to the invention is added to a wet alumina gel during the step of forming the support. One of the preferred methods of forming the carrier in the present invention is to knead at least one modified zeolite with a wet alumina gel for a few tens of minutes and then pass the resulting paste through a die to form extrudates with a diameter of between 0.4 and 4 mm. According to another preferred method of preparation, the modified zeolite can be introduced during the synthesis of the matrix. For example, according to this preferred embodiment of the present invention, the modified zeolite is added during the synthesis of the silicoaluminum matrix; the zeolite may be added to a mixture of an acidic alumina compound with a fully soluble silica compound.

The support can be shaped by any technique known to those skilled in the art. The shaping can be carried out for example by extrusion, pelletizing, by the method of coagulation in drop (oil-drop), by rotating plate granulation or by any other method well known to those skilled in the art.

At least one calcination may be performed after any of the steps of the preparation. The calcination treatment is usually carried out in air at a temperature of at least 150 ° C, preferably at least 300 ° C, more preferably at about 350 to 1000 ° C.

Group VIII elements and / or Group VIB elements, optionally at least one doping element chosen from boron, silicon and phosphorus and optionally the elements of groups IVB, and IB in the case of a catalyst based on reduced nickel, may be introduced, in whole or in part, at any stage of the preparation, during the synthesis of the matrix, preferably during the shaping of the support, or very preferably after the shaping of the support by any method known to those skilled in the art. They can be introduced after forming the support and after or before the drying and calcining of the support.

According to a preferred embodiment of the present invention, all or part of the elements of the groups VIII and / or the elements of the group VIB, optionally at least one doping element chosen from boron, silicon and phosphorus and possibly the elements of the groups IVB, and IB in the case of a reduced nickel catalyst, may be introduced during the shaping of the support, for example, during the mixing step of the modified zeolite with a wet alumina gel.

According to another preferred embodiment of the present invention, all or part of the elements of groups VIII, optionally at least one doping element chosen from boron, silicon and phosphorus and optionally the elements of groups IVB, and IB in the case of a reduced nickel-based catalyst can be introduced by one or more impregnation operations of the shaped and calcined support, by a solution containing the precursors of these elements. In a preferred manner, the support is impregnated with an aqueous solution. The impregnation of the support is preferably carried out by the "dry" impregnation method well known to those skilled in the art.

The following doping elements: boron and / or silicon and / or phosphorus can be introduced into the catalyst at any level of the preparation and according to any technique known to those skilled in the art.

In the case where the catalyst of the present invention contains at least one Group VIII metal, the Group VIII metals are preferably introduced by one or more impregnation operations of the shaped and calcined support, and after those of the group VIB or at the same time as the latter, in the case where said catalyst contains at least one Group VIII metal in combination with at least one Group VIB metal.

For example, among the sources of molybdenum and tungsten, it is possible to use oxides and hydroxides, molybdic and tungstic acids and their salts, in particular ammonium salts such as ammonium molybdate, ammonium heptamolybdate, ammonium tungstate, phosphomolybdic acid, phosphotungstic acid and their salts, silicomolybdic acid, silicotungstic acid and their salts. Oxides and ammonium salts such as ammonium molybdate, ammonium heptamolybdate and ammonium tungstate are preferably used.

Sources of non-noble group VIII elements that can be used are well known to those skilled in the art. For example, for non-noble metals, use will be made of nitrates, sulphates, hydroxides, phosphates, halides, for example chlorides, bromides and fluorides, carboxylates, for example acetates and carbonates.

The noble element sources of group VIII which can advantageously be used are well known to those skilled in the art. For the noble metals halides are used, for example chlorides, nitrates, acids such as hexachloroplatinic acid, hydroxides, oxychlorides such as ammoniacal oxychloride ruthenium. It is also advantageous to use cationic complexes such as ammonium salts when it is desired to deposit the metal on the Y-type zeolite by cation exchange.

The noble metals of group VIII of the catalyst of the present invention may advantageously be present in whole or in part in metallic and / or oxide form. The element (s) promoter (s) chosen (s) in the group formed by silicon, boron and phosphorus can advantageously be introduced by one or more impregnation operations with excess solution on the calcined precursor. The boron source may advantageously be boric acid, preferably orthoboric acid H3BO3, ammonium biborate or pentaborate, boron oxide, boric esters. The boron may for example be introduced in the form of a mixture of boric acid, hydrogen peroxide and a basic organic compound containing nitrogen such as ammonia, primary and secondary amines, cyclic amines, compounds of the family of pyridine and quinolines and compounds of the pyrrole family. Boron may be introduced for example by a boric acid solution in a water / alcohol mixture. The preferred phosphorus source is orthophosphoric acid H 3 PO 4, but its salts and esters such as ammonium phosphates are also suitable. The phosphorus may for example be introduced in the form of a mixture of phosphoric acid and a basic organic compound containing nitrogen such as ammonia, primary and secondary amines, cyclic amines, compounds of the family of pyridine and quinolines and compounds of the pyrrole family. Many sources of silicon can advantageously be employed. Thus, it is possible to use ethyl orthosilicate Si (OEt) 4, siloxanes, polysiloxanes, silicones, silicone emulsions, halide silicates, such as ammonium fluorosilicate (NH4) 2SiF6 or fluorosilicate. sodium Na2SiF6. Silicomolybdic acid and its salts, silicotungstic acid and its salts can also be advantageously employed. Silicon may advantageously be added for example by impregnation of ethyl silicate in solution in a water / alcohol mixture. Silicon can be added, for example, by impregnating a silicon-type silicon compound or silicic acid suspended in water. Group IB source materials that can be used are well known to those skilled in the art. For example, among copper sources, Cu (NO 3) 2 copper nitrate can be used.

The sources of Group IVB elements that can be used are well known to those skilled in the art. For example, among tin sources tin chloride SnCl 2 can be used.

The catalysts used in the process according to the invention advantageously have the form of spheres or extrudates. It is however advantageous that the catalyst is in the form of extrudates with a diameter of between 0.5 and 5 mm and more particularly between 0.7 and 2.5 mm. The shapes are cylindrical (which can be hollow or not), cylindrical twisted, multilobed (2, 3, 4 or 5 lobes for example), rings. The cylindrical shape is preferably used, but any other shape may be used. The catalysts according to the invention may optionally be manufactured and used in the form of crushed powder, tablets, rings, balls, wheels. In accordance with the invention, the metals of group VIB and / or group VIII of said catalyst are present in sulphide form, the sulphurization treatment being described below. In the case where the hydroisomerization catalyst contains at least one noble metal, the noble metal contained in said hydroisomerization catalyst must advantageously be reduced. One of the preferred methods for conducting the reduction of the metal is hydrogen treatment at a temperature between 150 ° C and 650 ° C and a total pressure of between 1 and 250 bar. For example, a reduction consists of a plateau at 150 ° C. for two hours and then a rise in temperature up to 450 ° C. at a rate of 1 ° C./min and then a two-hour stage at 450 ° C. throughout this reduction step, the hydrogen flow rate is 1000 normal m3 hydrogen / m3 catalyst and the total pressure kept constant at 1 bar. Any ex-situ reduction method can advantageously be considered.

According to step c) of hydroisomerization of the process according to the invention, at least a portion of the hydrocarbon base resulting from step b) is brought into contact, in the presence of hydrogen with said hydroisomerization catalyst, with operating temperatures and pressures advantageously to achieve a hydroisomerization of the non-converting filler. This means that the hydroisomerization is carried out with a conversion of the fraction 150 ° C + fraction 150 ° C "less than 20% by weight, preferably less than 10% by weight and very preferably less than 5% by weight. weight.

Thus, in accordance with the invention, step c) of hydroisomerization of the process according to the invention operates at a temperature of between 150 and 500 ° C., preferably between 150 ° C. and 450 ° C., and very preferably between 200 and 450 ° C, at a pressure of between 1 MPa and 10 MPa, preferably between 2 MPa and 10 MPa and very preferably between 1 MPa and 9 MPa, at an hourly space velocity advantageously between 0, 1 hr and 10 hr, preferably between 0.2 and 7 hr and very preferably between 0.5 and 5 hr, at a hydrogen flow rate such that the volume ratio hydrogen / The hydrocarbons are advantageously between 70 and 1000 Nm 3 / m 3 of filler, between 100 and 1000 normal m 3 of hydrogen per m 3 of filler and, preferably, between 150 and 1000 normal m 3 of hydrogen per m 3 of filler. eventual hydroisomerization stage operates at co-current. Characterization techniques The amount of cati an alkali group belonging to groups IA or IIA of the periodic table and preferably the amount of alkaline cation Na + remaining in the modified zeolite after the modifying treatment described above is measured by atomic adsorption according to a method known to those skilled in the art .

The acidity of Lewis and Bronsted zeolites is measured by Pyridine adsorption followed by infra-red spectroscopy (FTIR). The integration of the characteristic bands of the coordinated pyridine at 1455 cm -1 and the protonated pyridine at 1545 cm -1 makes it possible to compare the relative acidity of the Lewis and Bronsted catalysts, respectively. Before adsorption of the pyridine, the zeolite is pretreated under secondary vacuum at 450 ° C. for 10 hours with an intermediate stage at 150 ° C. for 1 hour. The pyridine is then adsorbed at 150 ° C. and then desorbed under secondary vacuum at this same temperature before taking the spectra.

The products, diesel base and kerosene, obtained according to the process according to the invention are endowed with excellent characteristics. The diesel base obtained is of excellent quality: its sulfur content is less than 10 ppm by weight. its total aromatics content is less than 5% by weight, and the polyaromatic content is less than 2% by weight. the cetane number is excellent, greater than 55. The density is less than 840 kg / m3, and most often less than 820 kg / m3. Its kinematic viscosity at 40 ° C is 2 to 8 mm 2 / s. • its cold-holding properties are compatible with current standards, with a filterability limit of less than -15 ° C and a cloud point below -5 ° C. The kerosene obtained has the following characteristics: a density of between 775 and 840 kg / m 3, a viscosity at -20 ° C. of less than 8 mm 2 / s, a point of disappearance of crystals of less than -47 ° C. a flash point Above 38 ° C a smoke point greater than 25 mm Examples Step a): Hydrotreatment In a temperature controlled reactor to provide isothermal and fixed bed operation loaded with 190 ml of nickel-based hydrotreatment catalyst and molybdenum, having a nickel oxide content equal to 3% by weight, and a content of molybdenum oxide equal to 16% by weight and a P2O5 content equal to 6%, the catalyst being previously sulphurized, 170 g / h are introduced pre-refined rapeseed oil with a density of 920 kg / m3 with a sulfur content of less than 10 ppm by weight, with a cetane number of 35 and the composition of which is detailed below: Fatty-chain fatty acid type glycerides % by mass Palmitic C16: 0 4 Palmitoleic C16: 1 <0.5 Stearic C18: 0 2 Oleic C18: 1 61 Linoleic C18: 2 Linoleic C18: 3 9 Arachidic C20: 0 <0.5 Gadoleic C20: 1 1 Behenic C22: 0 < 0.5 Erucic C22: 1 <1700 Nm3 of hydrogen / m3 of feed are introduced into the reactor maintained at a temperature of 300 ° C and a pressure of 5 MPa. Step b): separation of the effluent from step a). All the hydrotreated effluent from step a) is separated so as to recover the hydrogen-rich gases and a hydrocarbon base.

Step c): Hydroisomerization of the hydrotreated effluent from step b) on a catalyst according to the invention Preparation of the modified zeolite used in the catalyst according to the invention. 100 g of dealuminated HY zeolites with a Si / Al ratio of 11.5 and measured by NMR of silicon and aluminum are exchanged with a NaNO 3 solution to obtain the NaY cationic form of the Y zeolite. The exchange is carried out in a flask containing 1 L of NaNO 3 solution at 80 ° C for 2 hours, then the suspension is filtered and the zeolite is dried at 120 ° C overnight. The NaY zeolite obtained is poured into an IL-containing knitted balloon of anhydrous toluene and equipped with a refrigerant. After raising the temperature to 60 ° C., the amount of TEOS tetraethylorthosilicate molecular compound corresponding to 1% by weight of silica is introduced slowly into the zeolite suspension using a syringe pump. After stirring for 1 hour, the suspension is filtered and the zeolite dried at 120 ° C overnight. The modified zeolite is then exchanged 3 times with a 1N solution of NH 4 NO 3 to obtain the partially exchanged form NH 4 +, the exchange being carried out at a temperature of 80 ° C. The decomposition of TEOS and the transformation of NH4 + cations into protons is carried out under N 2 saturated with H 2 O at 350 ° C. for 2 hours, then a thermal treatment under pure N 2 is carried out at 450 ° C. for 2 hours. Characterizations of zeolites measured by atomic adsorption spectroscopy and pyridine adsorption monitored by Infra Red are given in Table 1.

Table 1: Characterization of the samples. Modified modified non-Y HY exchanged 3 times non-compliant (according to invention) Na / Al

amount of Na + remaining relative to the amount of NH4 + initially present (%)

Bronsted acid sites (au., 1545 cm-1 band) after desorption of pyridine at 150 ° C

Lewis acid sites (at 1455 cm-1 strip after desorption of pyridine at 150 ° C 0.001 0.05 0.1 5 5.5 5.0 3.7 1.5 Unmodified HY zeolite not in accordance with the invention, a dealuminated HY zeolite exchanged with a solution of NH4NO3 to obtain the cationic form of zeolite Y but which has not been modified according to the modification method described according to the invention, the analytical results show that the quantity of sites Bronsted acid decreases slightly and the amount of Lewis acid sites decreases significantly on the modified zeolites.This variation in acidity varies inversely with the amount of sodium present in the samples.

Preparation of catalysts The catalyst supports according to the invention containing the modified or unmodified zeolites are manufactured using 19.5 g of zeolite mixed with 80.5 g of a matrix composed of ultrafine tabular boehmite or alumina gel marketed under the US Pat. SB3 name by Condéa Chemie GmbH. This powder mixture is then mixed with an aqueous solution containing nitric acid at 66% by weight (7% by weight of acid per gram of dry gel) and then kneaded for 15 minutes. The kneaded paste is then extruded through a die having a diameter of 1.2 mm. The extrudates are then calcined at 500 ° C. for 2 hours in air. The carrier extrudates thus prepared are dry impregnated with a solution of a mixture of ammonium heptamolybdate and nickel nitrate and calcined in air at 550 ° C. in situ in the reactor. The oxide weight contents of the catalysts obtained are given in Table 2. TABLE 2 Characteristics of the catalysts Zeolite at the base of the modified non-modified HY catalyst Y 3 modified according to the invention MoO 3 (% by weight) 12.1 12.4 NiO (% by weight) 3.2 3.1 SiO 2 (% by weight) total 14.7 14.1 100% supplement (mainly 70.0 70.4 composed of Al2O3 (% wt) The hydrotreated hydrocarbon effluent obtained at the end of step b / is hydroisomerized with hydrogen lost in a hydroisomerisation reactor under the operating conditions below: WH (charge volume / catalyst volume / hour) = 1 h "- total working pressure: 5 MPa temperature 300 ° C hydrogen / feed ratio: 700 normal liters / liter The reaction temperature is set from way to achieve a gross conversion (denoted CB) equal to 70% weight.

50 ppm by weight of dimethyl disulfide is added to the feedstock in order to simulate the partial pressures of H 2 S and to maintain the catalyst in sulphurized form. The feedstock thus prepared is injected into the hydroisomerization test unit which comprises a fixed-bed, upflow-flow reactor ("up-flow") into which 100 ml of catalyst is introduced. The catalyst is sulphurized with a straight-run diesel / DMDS and aniline mixture up to 320 ° C. It should be noted that any in situ or ex situ sulphurization method is suitable. Once the sulphurization is complete, the charge can be transformed. The operating conditions of the test unit are indicated above. The yield of jet fuel (kerosene, 150-250 ° C. cut, below Yt Kero) is equal to the weight percentage of compounds having a boiling point of between 150 and 250 ° C. in the effluents. The diesel yield (250 ° C + cut) is equal to the weight percentage of compounds having a boiling point greater than 250 ° C in the effluents.

The temperature of 300 ° C is adjusted so as to have a conversion of the fraction 150 ° C + fraction 150 ° C- less than 5% by weight during the hydroisomerisation in the case where the hydroisomerisation catalyst used in the step c) of the process according to the invention contains the zeolite modified according to the invention. In Table 3, we have reported the temperature yields of kerosene and diesel for the catalysts described in the examples above.

Table 3: Catalytic Activities of Catalysts in Hydroisomerization. Yield 150 ° C. Yield kerosene (% wt) Diesel yield (% wt) HY unmodified 13 30 57 Y modified 62 exchanged 3 times 5 33 (according to the invention) At a temperature of 300 ° C., the process using a catalyst containing an unmodified zeolite results in the production of a light cut 150 ° C- at a yield of 13% and thus the production of middle distillate at a lower yield compared to the setting of a work of a catalyst containing a zeolite modified according to the invention. The method according to the invention thus demonstrates that the catalyst containing a zeolite modified according to the invention and used in said process according to the invention is more active than the non-compliant catalysts to obtain a conversion level of the fraction 150 ° C + less than 5% by weight, while making it possible to obtain higher middle distillate yields, and therefore better selectivity for middle distillates, compared to a hydroisomerization process using a non-compliant catalyst containing an unmodified or modified zeolite in a manner not in accordance with the invention.

Claims (14)

REVENDICATIONS1. Process for the treatment of charges originating from a renewable source comprising the following steps: a) hydrotreatment in the presence of a catalyst in a fixed bed, at a temperature of between 200 and 450 ° C., at a pressure of between 1 MPa and 10 MPa, at a space velocity of between 0.1 h "1 and 10 h" "and in the presence of a total amount of hydrogen mixed with the feed such that the hydrogen / feed ratio is between 70 and 1000 Nm 3 of hydrogen / m3 of feed, b) separation from the effluent from step a) hydrogen, gases and at least one hydrocarbon base, c) hydroisomerization of at least a portion of said hydrocarbon base of step b) in the presence of a fixed bed hydroisomerization catalyst, said catalyst comprising at least one hydro-dehydrogenating metal selected from the group consisting of Group VIB metals and Group VIII of the Periodic Table and a support comprising a zeolite comprising at least one series of channels whose opening is defined by an 8-atom oxygen ring, modified by a ') at least one step of introducing at least one alkaline cation belonging to groups IA or IIA of the periodic classification, b ') a step of treating said zeolite in the presence of at least one molecular compound containing at least one silicon atom, c') at least one step of partial exchange of said alkaline cations by NH 4 + cations and at least one heat treatment step, said hydroisomerization step being carried out at a temperature between 150 and 500 ° C, at a pressure of between 1 MPa and 10 MPa, at a space velocity of between 0.1 and 10 h -1 and in the presence of a total amount of hydrogen mixed with the feed such that the hydrogen / feed ratio is between 70 and 1000 Nm 3 / m 3 of feed, d) separation, from the effluent from step c) hydrogen, gases and at least one diesel base and a kerosene base. 2. The method of claim 1 wherein the group VIII element is selected from platinum and palladium, taken alone or in admixture. 3. Method according to claim 2 wherein said catalyst comprises, in% by weight relative to the total mass of the catalyst, a noble metal content of between 0.01 and 10% by weight. 4. The process as claimed in claim 1, in which the catalyst comprises at least one Group VIB metal in combination with at least one Group VIII non-noble metal, the Group VIB metal content being comprised, in oxide equivalent, of between 5 and 40. % by weight relative to the total mass of said catalyst, and the non-noble metal content of group VIII being in oxide equivalent, between 0.5 and 10% by weight relative to the total mass of said catalyst. 5. The method of claim 4 wherein the non-noble group VIII element is selected from iron, cobalt and nickel, alone or in admixture. 6. Method according to one of claims 4 or 5 wherein the group VIB element is selected from tungsten and molybdenum. 7. Method according to one of claims 1 to 6 wherein the zeolite contained in the support of the catalyst used in step c) of the process according to the invention is selected from zeolites Y, ZSM-48, ZBM-30 , IZM-1 and COK-7, taken alone or as a mixture. 8. Process according to claim 7, in which the zeolite initially used is zeolite Y. 9. Method according to one of claims 1 to 8 wherein said alkali cation belonging to groups IA and IIA introduced in step a) is selected from Na +, Li +, K +, Rb +, Cs +, Ba2 + and Ca2 + cations and preferably, said cation is the Na + cation. 25 10. Method according to one of claims 1 to 9 wherein the molecular compound containing at least one silicon atom used in the treatment step b) is selected from compounds of formula Si-R4 and Si2-R6 where R is selected from hydrogen, alkyl, aryl, acyl, alkoxy (O-R '), hydroxyl (-OH) or halogen. 30 11. Method according to one of claims 1 to 10 wherein the remaining alkali cations content in the zeolite modified at the end of step c) is such that the molar ratio alkali metal cation / aluminum is between 0.2 : 1 and 0.01: 1. 20 12. The method of claim 11 wherein the remaining alkali cations content in the zeolite modified at the end of step c) is such that the molar ratio alkali metal / aluminum is between 0.2: 1 and 0.015: 1 13. The method of claim 11 wherein the remaining alkali cations content in the modified zeolite at the end of step c) is such that the molar ratio of alkali metal cation / aluminum is between 0.15: 1 and 0, 02: 1. 14. Method according to one of claims 1 to 13 wherein the charges from renewable sources are chosen from oils and fats of plant or animal origin, or mixtures of such fillers, containing triglycerides and / or fatty acids. and / or esters and said vegetable oils which may be raw or refined, wholly or in part, and derived from the following plants: rapeseed, sunflower, soya, palm, palm kernel, olive, coconut, jatropha, and animal fats being selected from fat or fat composed of residues from the food industry or from the food service industries.