RU2802184C2 - Polymetallic catalyst doped with phosphorus and yttrium - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to the field of hydrocarbon conversion, more specifically to reforming of hydrocarbon raw materials in the presence of a catalyst for the production of gasoline fractions and aromatic compounds. The catalyst contains substrate, at least one noble metal M, tin, phosphorus, yttrium, and a halogen compound. The phosphorus content is from 0.4 to 0.8% by wt. relatively to the catalyst weight. The yttrium content is more than or equal to 0.01% by wt. and less than 0.5% by wt. relatively to the catalyst weight. At the same time, substrate contains silicon oxide, aluminum oxide, or aluminosilicate. The invention also relates to a method for the production of this catalyst and to its use in the reforming process.

EFFECT: provision of a catalyst with increased selectivity and stability during reforming without loss of activity.

16 cl, 1 tbl, 12 ex

Description

The present invention relates to the field of hydrocarbon conversion, more specifically to the reforming of hydrocarbon feedstock in the presence of a catalyst to produce gasoline cuts and aromatics. More specifically, the invention relates to an improved catalyst based on at least one noble metal, tin, phosphorus and yttrium, its production process and its use in a reforming process.

Catalytic reforming processes can significantly increase the octane number of gasoline fractions obtained by direct distillation of crude oil and/or other petroleum refining processes, such as, for example, catalytic cracking or thermal cracking. The catalytic reforming process is a long-standing method in refineries aimed at increasing the cost of heavy gasoline obtained by distillation. The hydrocarbons of the heavy gasoline feedstock (namely, paraffins and naphthenes) - containing from about 5 to 12 carbon atoms per molecule - are transformed into aromatic hydrocarbons and branched paraffins in this way. This transformation is achieved at high temperature (on average, in the range from 480 to 520°C), low average pressure (from 0.2 to 2.5 MPa) and in the presence of a catalyst. As a result of catalytic reforming, a reformed product is obtained, which allows a significant increase in the octane number of oil fractions, and hydrogen. The reformate is formed mainly by C ₅₊ compounds (containing at least 5 carbon atoms).

The reforming catalysts are polymetallic catalysts. There are two broad categories of reforming catalysts characterized by different properties: platinum-tin catalysts, used mostly in the form of beads in a moving bed reactor in processes referred to as CCR (Continuous Catalytic Reforming, according to English terminology), and platinum-rhenium catalysts used, for the most part, in the form of extrudates in a fixed bed.

Numerous patents describe the addition of promoters to these two types of catalysts in order to increase their efficiency in the hydrocarbon feed reforming process.

With regard to doping with lanthanides, namely cerium, US Pat. No. 2,814,599 describes the addition of promoters such as gallium, indium, scandium, yttrium, lanthanum, thallium or actinium to platinum or palladium based catalysts. US 2013/0015103 describes catalysts containing Ce (PtSnCe). US 2013/0256194 describes catalysts of the same type in combination with alkaline compounds at a very low concentration. Document EP 1390140 describes catalysts doped with Ce and/or Eu. Documents CN 103372454 and SU 6239063 are devoted to catalysts containing, in addition to Ce, other lanthanides in one catalyst. CN 105771981 claims the combined use of Ce and Y in the same catalyst of the PtSn type.

At the same time, it is known that phosphorus increases the yield of hydrocarbon compounds with a strictly greater than 4 number of carbon atoms (C ₅₊ ), in particular, aromatic products. This property is claimed in patents SU 2890167, SU 3706815, SU 4367137, SU 4416804, SU 4426279 and SU 4463104.

SU 2012/122665 describes a catalyst containing platinum, tin, phosphorus and at least one promoter selected from the group consisting of gallium, indium, thallium, arsenic, antimony and bismuth.

Document EP 1656991 describes a catalyst containing platinum, tin with a Pt/Sn ratio of less than 0.9 and, in some cases, another element selected from germanium, gallium, cerium, lanthanum, europium, indium, phosphorus, nickel, iron, tungsten , molybdenum, zinc or cadmium, individually or in a mixture, in an elemental content of 0.1 to 10% wt. relative to the mass of the catalyst, however, without indicating any particular influence of the promoters.

SU 2007/0215523 also discloses that the addition of small amounts of phosphorus, less than 0.4 wt%, stabilizes the support, allowing better surface area retention and chlorine retention when used as a catalyst in catalytic reforming processes. This document discloses a catalyst based on platinum and phosphorus, optionally containing another element selected from tin, rhenium, germanium, lead, indium, gallium, iridium, lanthanum, cerium, boron, cobalt, nickel and iron, individually or in mixture, in elemental content from 0.01 to 5% wt. relative to the weight of the catalyst.

In this context, the aim of the invention is to provide a catalyst having improved selectivity and stability during the reforming process without sacrificing activity.

By selectivity is meant the yield of C ₅₊ compounds, expressed as a mass percentage relative to the effluent at a given level of activity (usually a given level of octane number).

Activity is usually defined as the octane number of C ₅₊ compounds at the level of requirements or, conversely, expressed in terms of the temperature required to achieve a given octane number (also called RON, Research Octane Number, research octane number according to English terminology).

Stability is understood as stable activity, usually measured as the increase in the amount of heat supplied during the operation of the installation, per unit of time or feed, necessary to maintain a given octane number.

The invention relates to a catalyst containing a support containing at least one noble metal M, tin, phosphorus and yttrium, wherein the elemental content of phosphorus is less than or equal to 1% wt., the content of yttrium is less than or equal to 1% wt. relative to the weight of the catalyst.

It has been demonstrated that the simultaneous presence of a phosphorus promoter and a yttrium promoter, with each promoter present in a certain amount in a noble metal and tin catalyst, gives the finished catalyst selectivity and stability superior to prior art catalysts containing only one from these promoters. Without wishing to be bound by theory, it is believed that the simultaneous presence of the phosphorus promoter in an amount of less than 1% by weight, preferably from 0.3 to 1% by weight, more preferably from 0.4 to 0.8% by weight ., and the promoter - yttrium in an amount less than or equal to 1% wt., preferably from 0.01 to 0.5% wt. relative to the weight of the catalyst unexpectedly has a synergistic effect, increasing selectivity and stability, while this synergistic effect is unpredictable based on a simple addition of the known effects of these promoters.

According to one embodiment of the invention, the noble metal M is present in an amount of from 0.02 to 2% by weight. relative to the weight of the catalyst.

According to one embodiment of the invention, the noble metal M is platinum or palladium.

According to one embodiment of the invention, the tin content is from 0.005 to 10% by weight. relative to the weight of the catalyst.

According to one embodiment of the invention, the yttrium content is from 0.01 to 0.5% by weight. relative to the weight of the catalyst.

According to one embodiment of the invention, the phosphorus content is from 0.3 to 1 wt%. relative to the weight of the catalyst.

According to one embodiment of the invention, the atomic ratio Sn/M is from 0.5 to 4.0, the ratio P/M is from 0.2 to 30.0, the ratio Y/M is from 0.1 to 5.0.

According to one embodiment of the invention, the substrate contains silicon oxide, alumina or aluminosilicate.

According to one embodiment of the invention, the catalyst also contains a halogen compound.

According to this variant, the content of the halogen compound is from 0.1 to 8% by weight. relative to the weight of the catalyst.

The invention also relates to a process for the preparation of a catalyst according to the invention, comprising the following successive steps, in which:

a) prepare a precursor containing a substrate, tin, phosphorus and a noble metal,

b) drying the precursor obtained in step a) in a neutral gas stream or in a gas stream containing oxygen at a temperature of less than 200°C and calcining at a temperature of from 350 to 650°C,

c) impregnating the dried and calcined precursor obtained in step b) with an impregnation solution containing a yttrium precursor,

d) drying the impregnated precursor obtained in step c) in a neutral gas stream or in a gas stream containing oxygen at a temperature of less than 200°C and calcined at a temperature of from 350 to 650°C.

According to one embodiment of the invention, stage a) includes the following stages, in which:

a1) preparing a substrate containing tin by introducing a tin precursor during the formation of the substrate,

a2) impregnating the tin-containing substrate obtained in step a1) with an impregnating solution containing at least a noble metal precursor and a phosphorus precursor.

According to one embodiment of the invention, stage a) includes the following stages, in which:

a1') prepare a substrate containing tin and phosphorus by introducing a tin precursor and a phosphorus precursor during the formation of the substrate,

a2') impregnate the tin-phosphorus-containing substrate obtained in step a1') with an impregnating solution containing at least a noble metal precursor.

According to another embodiment of the invention, the catalyst obtained after step d) is treated with hydrogen.

The invention also relates to the use of the catalyst according to the invention in a reforming process.

Further, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, éditeur CRC press, rédacteur en chef D.R. Lide, 81ème édition, 2000-2001). For example, group VIII according to the CAS classification corresponds to metals 8, 9 and 10 columns according to the new IUPAC classification.

In all cases, the contents of the various catalyst components, including noble metal, tin, phosphorus, yttrium, and halogen compound, are expressed relative to the element, unless otherwise indicated.

DETAILED DESCRIPTION OF THE INVENTION

Catalyst

The invention relates to a catalyst containing a support containing at least one noble metal M, tin, phosphorus and yttrium, wherein the elemental content of phosphorus is less than or equal to 1% wt., the content of yttrium is less than or equal to 1% wt. relative to the weight of the catalyst.

The substrate generally includes at least one oxide selected from the group consisting of oxides of magnesium, titanium, zirconium, aluminium, silicon. Preferably, the substrate comprises silica, alumina or aluminosilicate, most preferably alumina. Preferably the support comprises alumina, most preferably the alumina is gamma alumina. Advantageously, the substrate has a total pore volume of 0.1 to 1.5 cm ³ /g, more preferably 0.4 to 0.8 cm ³ /g. The total pore volume is measured by mercury porosimetry according to ASTM D4284 at a contact angle of 140°, as described by Rouquerol F.; Rouquerol J.; Singh K. "Adsorption by Powders & Porous Solids: Principle, methodology and applications", Academic Press, 1999, for example using a Microméritics™ model Autopore III™ instrument.

The specific surface area of the substrate is preferably 50 to 600 m ² ⋅g ^-1 , preferably 100 to 400 m ² ⋅g ^-1 , more preferably 150 to 300 m ² ⋅g ^-1 . In the context of the present invention, the specific surface area is determined by the BET (Brunauer-Emmett-Teller) method according to ASTM D3663, this method is described in the work cited above.

Advantageously, the support is characterized by a packing density (densité de remplissage tassée, DRT) of 0.4 to 0.8 g/ml, preferably 0.5 to 0.7 g/ml. The DRT measurement consists of introducing a support into a test tube (usually 100 ml) of a predetermined volume and compacting with vibration until a constant volume is reached. The apparent bulk density of the compacted product is calculated by comparing the weight of the substrate introduced and the volume occupied by it after compaction. The measurement error is typically in the order of ±0.01 g/mL.

Thus, the support, when used as a reforming catalyst support, satisfies both the requirement for a support to be referred to as dense (for example, with a packing density in the range of 0.6 to 0.7 g/mL) and the requirement that applied to the substrate, referred to as light (for example, with a packing density in the range from 0.5 to 0.6 g/ml).

Preferably, the packing density value (DRT) of said support is from 0.5 to 0.7 g/ml.

Preferably, the support is in the form of beads, extrudates, tablets or powder. Preferably, the support is in the form of beads. The substrate can be obtained by any method known to those skilled in the art. Shaping can be done, for example, by extrusion, tableting, oil drop method, turntable granulation, or any other method known to those skilled in the art.

When the substrate is in the form of balls, their diameter is generally 0.5 to 5 mm. Such a ball can be made by the method of drop coagulation. According to this method, and when the substrate is alumina, a slurry is prepared containing an alumina gel (such as bomite (crystallized aluminum oxyhydroxide) or pseudobomite), an emulsifier, optionally metal precursors, and water, and the slurry is placed in a drop-forming tank, equipped with nozzles, the holes of which allow drops to form. Thus, the slurry under the action of gravity forms droplets in a column, in the upper part of which there is an organic phase (oil phase), and in the lower part there is an aqueous main phase (ammonia solution), and spheroidal particles are collected in the lower part of the aqueous main phase. During the passage of the droplet through the organic phase, sphere formation occurs, while gelation (or coagulation) occurs in the aqueous phase. After that, the balls are dried and fired.

When the support is in the form of extrudates, they can be prepared by mixing the alumina gel with water and appropriate peptizing agents such as hydrochloric or nitric acid, in the presence of metal precursors, if desired, until an extrudable mass is formed (stirring). with acid using shear forces). The resulting mass can be extruded through an appropriately sized die to form extrudates which are then dried and fired. Sometimes it may be necessary to add a neutralizing agent, such as an ammonia solution, before extrusion. In general, the diameter of the extrudates is 0.5 to 5 mm, preferably with a length to diameter ratio of 1:1 to 5:1.

The essential component of the catalyst according to the invention is the noble metal M, preferably platinum or palladium, most preferably platinum. The noble metal may exist in the finished catalyst as an oxide, sulfide, halide, oxyhalide, in chemical combination with one or more other catalyst components, or in the form of an elemental metal.

The content of the noble metal M in the catalyst according to the invention is from 0.02 to 2% by weight, preferably from 0.05 to 1.5% by weight, more preferably from 0.1 to 0.8% by weight. relative to the weight of the catalyst.

Another important component of the catalyst according to the invention is tin. This element may be present in the finished catalyst as an oxide, sulfide, halide, oxyhalide, in chemical combination with one or more other catalyst components, or in the form of an elemental metal.

The tin content of the catalyst according to the invention is from 0.005 to 10% by weight, preferably from 0.01 to 5% by weight, more preferably from 0.1 to 1% by weight.

Another important component of the catalyst according to the invention is phosphorus. This element may be present in the finished catalyst as an oxide or mixed oxide, phosphates, polyphosphates, sulfide, halide, oxyhalide, hydride, or in chemical combination with one or more other catalyst components.

The elemental content of phosphorus in the catalyst according to the invention is less than or equal to 1% by weight, preferably from 0.3 to 1% by weight, particularly preferably from 0.4 to 0.8% by weight. Preferably, phosphorus is added by impregnation.

Another important component of the catalyst according to the invention is yttrium. Yttrium may be present in the finished catalyst as an oxide, sulfide, halide, oxyhalide, chemically combined with one or more other catalyst components, or in the form of an elemental metal.

The elemental content of yttrium in the catalyst according to the invention is less than or equal to 1% by weight, preferably from 0.01 to 0.5% by weight, particularly preferably from 0.02 to 0.3% by weight. relative to the weight of the catalyst. Preferably, yttrium is added by impregnation.

The simultaneous presence of phosphorus in an amount less than or equal to 1% wt., preferably, ranging from 0.3 to 1% wt., and yttrium in an amount less than or equal to 1% wt. relative to the mass of the catalyst, unexpectedly has a synergistic effect on the most important parameters of the catalyst - selectivity and stability - without reducing activity.

The atomic ratio Sn/M is generally 0.5 to 4.0, more preferably 0.9 to 3.5, most preferably 0.95 to 3.2.

The P/M ratio is generally 0.2 to 30.0, more preferably 0.5 to 20.0, most preferably 0.9 to 15.0.

The Y/M ratio is generally 0.1 to 5.0, more preferably 0.2 to 3.0.

The catalyst according to the invention may also preferably include a halogen compound selected from the group consisting of fluorine, chlorine, bromine and iodine. The content of the halogen compound is generally 0.1 to 8% by weight, preferably 0.2 to 3% by weight. catalyst after firing. Preferably, the halogen compound is chlorine.

In certain cases, the catalyst according to the invention may also include other promoters selected from groups IA, IIA, IIIA (in particular indium), IVA (in particular germanium) and VA of the periodic system, cobalt, nickel, iron, tungsten, molybdenum, chromium, bismuth, antimony, zinc, cadmium and copper. When these elements are present in the catalyst, their content in terms of oxide, in general, is from 0.01 to 2% wt., preferably, from 0.05 to 1% wt. relative to the weight of the catalyst.

However, preferably the catalyst is formed from a support of at least one noble metal M, tin, phosphorus and yttrium, particularly preferably formed from a support made from alumina, platinum, tin, phosphorus and yttrium, wherein phosphorus and yttrium are present. in the amounts indicated above.

All elements are preferably evenly distributed in the substrate.

Catalyst production method

The catalyst according to the invention can be obtained by any production method known to those skilled in the art.

The noble metal may be incorporated into the substrate in any appropriate manner, such as co-deposition, ion exchange, or impregnation. Preferably, it is introduced by impregnation of the preformed substrate, for example by impregnation with excess or exactly (the volume of the solution containing the element to be introduced corresponds exactly to the pore volume of the substrate), preferably by impregnation with excess. To do this, the substrate is impregnated with an impregnating solution containing at least a noble metal.

In general, hydrochloric acid, or the like, may also be added to the impregnating solution to further facilitate penetration or fixation on the surface of the noble metal substrate, or uniform distribution of the metal components throughout the substrate material.

In addition, it is generally preferred to impregnate the substrate after it has been fired to minimize the risk of precious metal leaching.

When the noble metal is platinum, the platinum precursors are among others part of the following group: hexachloroplatinic acid, bromoplatinic acid, ammonium chloroplatinate, platinum chloride, platinum dichlorocarbonyl dichloride, teraammineplatinum chloride, or dihydroxyplatinum diammine. Organic platinum complexes such as platinum(II) diacetylacetonate can also be used. Preferably, the platinum precursor used is hexachloroplatinic acid.

The tin may be incorporated into the support in any appropriate manner, such as by co-precipitation, ion exchange, or impregnation, at any stage of the catalyst preparation process.

According to the first option, tin can be introduced into the substrate, for example, during the synthesis of the substrate or during the molding of the substrate. Can be used, among others, methods of adding before or during the dissolution of oxide precursors of the support during the synthesis of the support, with or without aging. Thus, the introduction may be simultaneous or sequential with mixing of the support precursors. Tin can be introduced during the synthesis of the substrate according to the sol-gel technology or added to the alumina sol. Tin can also be introduced during the manufacture of the substrate by prior art substrate molding methods such as extrusion molding or oil drop molding.

According to the second variant, tin can be introduced into the substrate, for example, by impregnating a preformed substrate. Impregnation of the substrate with a solution containing one or more tin precursors can be carried out in excess of the solution or exactly. The impregnation can be carried out in the presence of compounds that affect the interaction between the tin precursor and the substrate. These compounds may be, for example, but not limited to, mineral acids (HCl, HNO ₃ ) or organic acids (such as carboxylic or polycarboxylic acids) and complex organic compounds, as described, for example, in US Pat. carried out by any method known to those skilled in the art, which allows to achieve a homogeneous distribution of tin in the catalyst.

Tin precursors can be mineral or organometallic, in certain cases, water-soluble organometallic compounds. The tin precursor may be selected from the group consisting of halogen compounds, hydroxides, carbonates, carboxylates, sulfates, tartrates and nitrates. These forms of tin can be introduced ready-made into the catalyst preparation medium or synthesized therein (for example, by introducing tin and carboxylic acid). Tin organometallic type precursors may be, for example, SnR ₄ where R is an alkyl group, such as butyl, Me ₃ SnCl, Me ₂ SnCl ₂ , Et ₃ SnCl, Et ₂ SnCl ₂ , EtSnCl ₃ , iPrSnCl ₂ and Me hydroxides ₃ SnOH, Me ₂ Sn(OH) ₂ , Et ₃ SnOH, Et ₂ Sn(OH) ₂ , oxides (Bu ₃ Sn) ₂ O, Bu ₃ SnOC(O)Me acetate. Preferably, halogen tin compounds are used, in particular chlorinated ones. In particular, SnCl ₂ or SnCl ₄ is preferably used.

According to a third variant, the tin can also be introduced partly during the synthesis or molding of the substrate and partly by deposition on the formed substrate.

Preferably, the tin is introduced into the substrate, that is, during the synthesis of the substrate or during the molding of the substrate. In the case of a bead-shaped alumina substrate obtained by the oil-drop process, the tin precursor is introduced into the suspension to form droplets.

Phosphorus may be introduced into the support by any suitable method such as co-precipitation, ion exchange or impregnation, and this may be done at any stage of the catalyst preparation process. In particular, it can be introduced in accordance with the three options described for tin.

According to one variant, phosphorus is introduced into the substrate, that is, during the molding of the substrate, for example, simultaneously with the tin.

According to another variant, the phosphorus is introduced by impregnation, particularly preferably, the phosphorus is introduced by impregnation at the same time as the noble metal. In this case, the impregnation solution contains a noble metal precursor and a phosphorus precursor.

Phosphorus precursors can be acids or salts, such as but not limited to H ₃ PO ₄ , H ₃ PO ₃ , H ₃ PO ₂ , NH ₄ H ₂ PO ₄ , (NH ₄ ) ₂ HPO ₄ .

Yttrium can be introduced into the support by any suitable method such as co-precipitation, ion exchange or impregnation and this can be done at any stage of the catalyst preparation process. In particular, it can be introduced in accordance with the three options described for tin. Preferably, it is introduced by impregnation, particularly preferably after the introduction of the noble metal, as described below.

The yttrium precursor may be selected from the group consisting of halogen compounds, hydroxides, carbonates, carboxylates, sulfates, tartrates and nitrates. These forms of yttrium can be introduced into the catalyst preparation medium or synthesized therein (for example, by introducing yttrium and a carboxylic acid). Preferably, for example, yttrium nitrate is used.

If other promoters are present, they may be incorporated into the support in any appropriate manner, such as co-precipitation, ion exchange, or impregnation, and this may be done at any stage of the catalyst preparation process. In particular, they can be introduced in accordance with the three options described for tin.

When a plurality of catalyst components are introduced into the support, that is, during the synthesis of the support or during the formation of the support, the introduction may be simultaneous or occur separately.

Once the components have been incorporated into the support, the procedure for preparing the catalysts according to the invention generally requires drying and calcining before depositing the noble metal and, in certain cases, other components. Drying, as a rule, is carried out at a temperature of from 50°C to 250°C, more preferably from 70°C to 200°C in air or in an inert atmosphere. Drying is preferably carried out for 1 to 24 hours, preferably 1 to 20 hours. Calcination is preferably carried out at a temperature of from 350°C to 650°C, preferably from 400°C to 600°C, more preferably from 450°C to 550°C, usually in air. The firing time is generally 0.5 hour to 16 hours, preferably 1 hour to 5 hours. The increase in temperature may be controlled or include intermediate plateaus, wherein these plateaus are reached at a constant or variable rate of temperature increase. Temperature plateaus can be the same or differ in speed (in degrees per minute or per hour).

When a plurality of catalyst components are introduced into the formed support by impregnation, the introduction of the components may be simultaneous, in a single impregnation solution, or separately using a plurality of impregnation solutions containing one or more components, in any order.

Any impregnation solution described in the context of the present invention may contain any polar solvent known to those skilled in the art. Said polar solvent may advantageously be selected from the group consisting of methanol, ethanol, water, phenol, cyclohexanol alone or in mixture. Said polar solvent can also advantageously be selected from the group consisting of propylene carbonate, dimethyl sulfoxide (DMSO), n-methylpyrrolidone (NMP) or sulfolane, alone or in admixture. Preferably, a protic polar solvent is used. A list of common polar solvents, as well as their dielectric constants, can be found in Solvents and Solvent Effects in Organic Chemistry, C. Reichardt, Wiley-VCH, 3eme edition, 2003, pages 472-474. Most preferably, the solvent used is water or ethanol, particularly preferably the solvent is ethanol.

After each impregnation operation, the impregnated catalyst is generally dried to remove all or part of the solvent introduced during the impregnation, preferably at a temperature of from 50°C to 250°C, more preferably at a temperature of from 70°C to 200°C. Preferably, drying is carried out for 1 to 24 hours, preferably 1 to 20 hours. Drying is carried out in air or an inert atmosphere (eg nitrogen).

After drying, the catalyst is typically calcined, usually in air. The firing temperature is generally 350°C to 650°C, preferably 400°C to 650°C, more preferably 450°C to 550°C. Temperature increases, in certain cases, may include intermediate temperature plateaus.

The firing time is generally 0.5 hour to 16 hours, preferably 1 hour to 5 hours.

More specifically, the catalyst according to the invention can be obtained in accordance with a production method comprising the following successive steps, in which:

a) prepare a precursor containing a substrate, tin, phosphorus and a noble metal,

b) drying the precursor obtained in step a) in a neutral gas stream or in a gas stream containing oxygen at a temperature of less than 200°C and calcining at a temperature of from 350 to 650°C,

c) impregnating the dried and calcined precursor obtained in step b) with an impregnation solution containing a yttrium precursor,

d) drying the impregnated precursor obtained in step c) in a neutral gas stream or in a gas stream containing oxygen at a temperature of less than 200°C and calcined at a temperature of from 350 to 650°C.

It is preferable to deposit yttrium on a solid material impregnated with a noble metal, in particular platinum, and phosphorus, previously dried and fired. Indeed, the introduction of yttrium after the noble metal and phosphorus makes it possible to avoid possible leaching of yttrium during the impregnation, preferably in excess, with the noble metal and phosphorus.

In step a), a support is prepared containing tin, phosphorus and a noble metal.

The tin may be introduced at any time during the preparation of the substrate, preferably during molding, or by impregnating an already formed substrate. Preferably, the tin is added during the molding of the substrate.

The same applies to phosphorus. Phosphorus can be introduced at any time during the preparation of the substrate, preferably during molding, or by impregnation of an already formed substrate. According to one embodiment, the phosphorus is introduced into the substrate, that is, during the molding of the substrate, preferably together with a tin compound. According to another variant, phosphorus is introduced by impregnation, particularly preferably it is introduced by impregnation at the same time as the noble metal.

The introduction of the noble metal onto the substrate can advantageously be carried out by one or more impregnations with an excess of solution, or by one or more impregnations with a precise amount of solution, preferably during one impregnation in excess of said substrate (preferably containing a tin compound and, in known cases, phosphorus) using a solution(s), preferably aqueous solution(s), containing a noble metal precursor and preferably a phosphorus precursor (when the substrate does not contain phosphorus or contains part of the phosphorus).

So, according to the first option, stage a) includes the following successive stages, in which:

a1) preparing a substrate containing tin by introducing a tin precursor during the formation of the substrate,

a2) impregnating the tin-containing substrate obtained in step a1) with an impregnating solution containing at least a noble metal precursor and a phosphorus precursor.

According to the second option, stage a) includes the following successive stages, in which:

a1') prepare a substrate containing tin and phosphorus by introducing a tin precursor and a phosphorus precursor during the formation of the substrate,

a2') impregnate the tin-phosphorus-containing substrate obtained in step a1') with an impregnating solution containing at least a noble metal precursor.

In step b), the precursor obtained in step a) is dried and calcined under the conditions described above.

In step c), the dried and calcined precursor obtained in step b) is impregnated with an impregnation solution containing at least a yttrium precursor. The introduction of yttrium can advantageously be carried out by one or more steps of impregnating the substrate with an excess of solution, preferably by means of one or more steps of impregnating said precursor with exactly the solution(s), preferably aqueous (s) containing a precursor of yttrium.

In step d) the precursor obtained in step c) is dried and calcined under the above conditions.

According to another embodiment, the catalyst according to the invention can be prepared by preparing a tin-containing support by introducing a tin precursor during the formation of the support and following by one or more impregnations of the support with an excess solution or one or more impregnations of the exact amount of solution, preferably a single impregnation of said precursor in in excess with solution(s), preferably aqueous solution(s), containing the noble metal precursor, the phosphorus precursor and the yttrium precursor, alone or in admixture, and drying and calcining under the above conditions.

When the various precursors used in the preparation of the catalyst according to the invention do not contain halogen or contain insufficient amounts of halogen, it may be necessary to add a halogen compound during preparation. Any compound known to those skilled in the art may be used and introduced into any of the steps in the preparation of the catalyst of the invention. In particular, it is possible to use organic compounds such as methyl or ethyl halides, for example dichloromethane, chloroform, dichloroethane, methyl chloroform or carbon tetrachloride.

The halogen can also be added by impregnation with an aqueous solution of an appropriate acid, such as hydrochloric acid, at any point in the preparation. A typical procedure is to impregnate the solid material so as to introduce the proper amount of halogen. The catalyst is brought into contact with the aqueous solution for a time sufficient to introduce this amount of halogen.

Chlorine can also be added to the catalyst according to the invention by oxychlorination. Such treatment can be carried out, for example, at a temperature of from 350 to 550°C for several hours with the supply of air containing a given amount of chlorine and, in certain cases, water.

Prior to use, the catalyst is subjected to hydrogen treatment to obtain an active metal phase. The procedure for such treatment consists, for example, in slowly increasing the temperature in a stream of hydrogen, pure or dilute, to a maximum reduction temperature lying, for example, from 100 to 600°C, preferably from 200 to 580°C, and then keeping at this temperature e.g. 30 minutes to 6 hours. Such restoration may be carried out immediately after firing, or later, by the user. Direct recovery of the dried product by the user is also possible.

Catalytic reforming process

The invention also relates to a process for the catalytic reforming of hydrocarbon feedstock in the presence of a catalyst according to the invention. The catalyst according to the invention can be used in gasoline reforming and aromatics production processes.

The reforming processes make it possible to increase the octane number of gasoline fractions obtained from the distillation of crude oil and/or other petroleum refining processes, such as, for example, catalytic cracking or thermal cracking. Methods for the production of aromatic compounds are used to obtain target products (benzene, toluene, xylenes) used in petrochemistry. These methods are of additional interest, providing the production of a significant amount of hydrogen, indispensable in the processes of hydrogenation and hydrotreating in oil refining.

Reforming feedstocks generally contain paraffinic, naphthenic and aromatic hydrocarbons having from 5 to 12 carbon atoms per molecule. This raw material differs, among other things, in its density and weight composition. This raw material may have an initial boiling point of 40°C to 70°C and a final boiling point of 160°C to 220°C. Raw materials can also be formed by one fraction or a mixture of gasoline fractions with initial and final boiling points from 40°C to 220°C. The feed can also be formed by heavy naphtha with a boiling point of 160°C to 200°C.

Typically, the reforming catalyst is loaded into the unit and preliminarily subjected to a reduction treatment as described above.

The feedstock is then fed in the presence of hydrogen at a hydrogen/hydrocarbon molar ratio of the feedstock, generally 0.1 to 10, preferably 1 to 8. Reforming operating conditions are generally as follows: temperature, preferably 400° C. to 600° C, more preferably 450°C to 540°C, pressure preferably 0.1 MPa to 4 MPa, more preferably 0.25 MPa to 3.0 MPa. All or part of the hydrogen produced can be recycled to the reformer inlet.

EXAMPLES

The following examples illustrate the invention.

Example 1 Preparation of Catalyst A1 Pt/Al ₂ O ₃ -Sn-Cl (comparative)

Bomite was synthesized by alkalizing a solution of 0.1 mol l ^-1 aluminum nitrate with a solution of 1 mol l ^-1 soda at room temperature and pH maintained at 10. The suspension was then kept for a week in an oven at 95° C. without stirring. After aging, the pH of the suspension was determined; the final pH was 11.5. The solid phase was separated by filtration, washed with a volume of water approximately equal to the original volume. The solid phase was resuspended in water and autoclaved at 150° C. for 4 hours. The suspension was centrifuged, then dried in a stream of air at room temperature.

The substrate of Example 1 was prepared using the bomite thus synthesized. A suspension containing 25% mineral material (percentage of Al ₂ O ₃ ) was prepared by mixing a sample of γ-alumina and powdered bomite in an acidified aqueous solution containing 15% of the mass. HNO ₃ /Al ₂ O ₃ . To this suspension was added tin dichloride so as to obtain 0.3% wt. tin in the finished solid material. The solid fraction of Al ₂ O ₃ was introduced to 88 wt%. due to bomite and 12% wt. due to γ-alumina. In addition, this suspension contained a blowing agent and a surfactant. The blowing agent was an organic phase containing a mixture of paraffins containing from 10 to 12 carbon atoms, with a boiling point of about 290°C and a density of 0.75 g/cm ³ . The surfactant was Galoryl ^TM . These components were introduced in the following proportions: mass fraction of blowing agent/water=1.4%, mass fraction of surfactant/blowing agent=6%.

This system was stirred at 600 rpm until a suspension with rheological properties suitable for drop formation was obtained (viscosity 250 MPa.s).

Carried out molding by drip coagulation. The dropping column was filled with a 28 g/l ammonia solution and an organic solution formed from the same oil fraction as the blowing agent used in the preparation of the emulsion. Suspension drops were obtained using calibrated nozzles. The beads were collected at the bottom of the column and placed in a 120°C ventilated oven with a humid air atmosphere containing 200 g water/kg dry air for 12 hours. The beads were then fired in dry air at 650°C for 3 hours. The beads obtained had a diameter of 1.9 mm.

Catalyst A1 was prepared on this support with the aim of depositing 0.3% by weight. platinum and 1% wt. chlorine on the finished catalyst. To 100 g of a tin-containing alumina support was added 400 cm ³ of an aqueous solution of hexachloroplatinic acid and hydrochloric acid. After contact for 4 hours, the liquid was drained. Drying was carried out at 120°C for 15 hours and firing at 500°C in an air stream with a flow rate of 100 l/h for 3 hours at a temperature increase rate of 7°C per minute.

The chlorine content is more than 1% wt. after firing brought to 1% wt. by partial thermal dechlorination at 520°C in dry air with the addition of 8000 ppmv water for 2.5 hours.

Catalyst A1 obtained after dechlorination contained 0.29% wt. platinum, 0.29% wt. tin and 1.03% wt. chlorine.

Example 2 Preparation of Catalyst A2 Pt/Al ₂ O ₃ -Sn-P-Cl (Comparative)

Bomite was synthesized by alkalizing a solution of 0.1 mol l ^-1 aluminum nitrate with a solution of 1 mol l ^-1 soda at room temperature and pH maintained at 10. The suspension was then kept for a week in an oven at 95° C. without stirring. After aging, the pH of the suspension was determined; the final pH was 11.5. The solid phase was separated by filtration, washed with a volume of water approximately equal to the original volume. The solid phase was resuspended in water and autoclaved at 150° C. for 4 hours. The suspension was centrifuged, then dried in a stream of air at room temperature.

The substrate of Example 2 was prepared using the bomite thus synthesized. A suspension containing 25% mineral material (percentage of Al ₂ O ₃ ) was prepared by mixing a sample of γ-alumina and powdered bomite in an acidified aqueous solution containing 15% of the mass. HNO ₃ /Al ₂ O ₃ . To this suspension were simultaneously added tin dichloride and phosphoric acid so as to obtain 0.3% wt. tin and 0.4% wt. phosphorus in the finished solid material. The solid fraction of Al ₂ O ₃ was introduced to 88 wt%. due to bomite and 12% wt. due to γ-alumina. In addition, this suspension contained a blowing agent and a surfactant. The blowing agent was an organic phase containing a mixture of paraffins containing from 10 to 12 carbon atoms, with a boiling point of about 290°C and a density of 0.75 g/cm ³ . The surfactant was Galoryl ^TM . These components were introduced in the following proportions: mass fraction of blowing agent/water=1.4%, mass fraction of surfactant/blowing agent=6%.

This system was stirred at 600 rpm until a suspension with rheological properties suitable for drop formation was obtained (viscosity 250 MPa.s).

Carried out molding by drip coagulation. The dropping column was filled with a 28 g/l ammonia solution and an organic solution formed from the same oil fraction as the blowing agent used in the preparation of the emulsion. Suspension drops were obtained using calibrated nozzles. The beads were collected at the bottom of the column and placed in a 120°C ventilated oven with a humid air atmosphere containing 200 g water/kg dry air for 12 hours. The beads were then fired in dry air at 650°C for 3 hours. The beads obtained had a diameter of 1.9 mm.

Catalyst A was prepared on this support with the aim of depositing 0.3% by weight. platinum and 1% wt. chlorine on the finished catalyst. To 100 g of a tin-containing alumina support was added 400 cm ³ of an aqueous solution of hexachloroplatinic acid and hydrochloric acid. After contact for 4 hours, the liquid was drained. Drying was carried out at 120°C for 15 hours and firing at 500°C in an air stream with a flow rate of 100 l/h for 3 hours at a temperature increase rate of 7°C per minute.

The chlorine content is more than 1% wt. after firing brought to 1% wt. by partial thermal dechlorination at 520°C in dry air with the addition of 8000 ppmv water for 2.5 hours.

Catalyst A obtained after dechlorination contained 0.29% wt. platinum, 0.28% wt. tin and 1.01% wt. chlorine.

Example 3 Preparation of Catalyst B YPt/Al ₂ O ₃ -Sn-Cl (comparative)

The substrate of example 3 was prepared in the same way as in example 2, except that tin dichloride was added to the suspension of bomite so as to obtain 0.3% wt. tin in the finished solid material.

The impregnation of this support with platinum in excess solution was carried out with the aim of depositing 0.3% by weight. platinum and 1% wt. chlorine on the finished catalyst, the same as in example 2.

After calcination, impregnation was carried out with the exact amount of yttrium nitrate solution so as to obtain 0.20% wt. on the finished catalyst. Before impregnation with yttrium, the catalyst was left overnight in a water-saturated atmosphere at room temperature. To 70 g of a tin-containing alumina support was added 42 cm ³ of an aqueous solution of yttrium nitrate. Left in contact for 30 minutes. After impregnation, the solid material was again left overnight to stand at room temperature in a water-saturated atmosphere. Then it was dried for 15 hours at 120°C and fired at 500°C in an air stream with a flow rate of 100 l/h for 3 hours at a temperature increase rate of 7°C per minute. The regulation of the chlorine content was carried out as described in example 2 for 2 hours.

Catalyst B obtained after dechlorination contained 0.29% wt. platinum, 0.31% wt. tin, 0.09% wt. yttrium and 1.00% wt. chlorine.

Example 4 Preparation of Catalyst C YPt/Al ₂ O ₃ -Sn-P _0.4 -Cl (according to the invention)

Catalyst C was prepared on the support of Example 2 containing 0.3% wt. tin and 0.4% wt. phosphorus, by impregnation with platinum, then with yttrium, as described in example 3.

Catalyst C obtained after dechlorination contained 0.32% wt. platinum, 0.08% wt. yttrium, 0.29% wt. tin, 0.419% phosphorus and 1.04% wt. chlorine.

Example 5 Preparation of catalyst D YPt/Al ₂ O ₃ -Sn-P _0.8 -Cl (according to the invention)

The substrate of example 5 was prepared in the same way as in example 2, except that the target content of phosphorus in the finished catalyst was 0.8 wt%. Then impregnation was carried out with platinum, then with yttrium, as described in example 2.

Catalyst D obtained after dechlorination contained 0.29% wt. platinum, 0.08% wt. yttrium, 0.29% wt. tin, 0.76% phosphorus and 1.01% wt. chlorine.

Example 6 Preparation of Catalyst E PtY/Al ₂ O ₃ -Sn-P _0.4 -Cl (according to the invention)

Catalyst E was prepared on the support of example 2 containing 0.3% wt. tin and 0.4% wt. phosphorus, by impregnation with yttrium, then platinum, which differs from example 3 in the order of making these elements by impregnation. Target content of 0.08% wt. yttrium and 0.30% wt. platinum was similar.

Catalyst E obtained after dechlorination contained 0.31% wt. platinum, 0.07% wt. yttrium, 0.30% wt. tin, 0.38% phosphorus and 0.98% wt. chlorine.

Example 7: Preparation of catalyst F YPt/Al ₂ O ₃ -Sn-P _0.3 -Cl (according to the invention)

The substrate of example 7 was prepared in the same way as in example 2, except that the target content of phosphorus in the finished catalyst was 0.3% wt. Then impregnation was carried out with platinum, then with yttrium, as described in example 3.

Catalyst F obtained after dechlorination contained 0.29% wt. platinum, 0.07% wt. yttrium, 0.31% wt. tin, 0.31% phosphorus and 1.04% wt. chlorine.

Example 8 Preparation of Catalyst G YPt/Al ₂ O ₃ -Sn-P _1.15 -Cl (Comparative)

The substrate of example 8 was prepared in the same way as in example 2, except that the target content of phosphorus in the finished catalyst was 1.15 wt%. Then impregnation was carried out with platinum, then with yttrium, as described in example 2.

Catalyst G obtained after dechlorination contained 0.30% wt. platinum, 0.08% wt. yttrium, 0.31% wt. tin, 1.17% phosphorus and 0.97% wt. chlorine.

Example 9: Preparation of catalyst H YPt/Al ₂ O ₃ -Sn-P _0.4 -Cl (according to the invention)

Catalyst H was prepared on the support of Example 2 containing 0.3% wt. tin and 0.4% wt. phosphorus, by impregnation with platinum, then yttrium, as described in example 3, with the only difference that the target content of yttrium was 0.50% wt.

Catalyst H obtained after dechlorination contained 0.30% wt. platinum, 0.48% wt. yttrium, 0.30% wt. tin, 0.39% phosphorus and 1.01% wt. chlorine.

Example 10 Preparation of catalyst I YPtP _0.4 /Al ₂ O ₃ -Sn-Cl (according to the invention)

The substrate of example 3 was prepared in the same way as in example 2, except that tin dichloride was added to the suspension of bomite to obtain 0.3% wt. in the finished catalyst.

Impregnation with platinum in excess of the solution was carried out as described in example 2, with the only difference that phosphoric acid was added to the solution of hexachloroplatinic acid so as to obtain 0.4% wt. in the finished catalyst. Impregnation with the exact amount of yttrium nitrate solution was as described in example 3. Heat treatment was similar to example 3.

Catalyst I obtained after dechlorination contained 0.291% wt. platinum, 0.08% wt. yttrium, 0.31% wt. tin, 0.38% phosphorus and 1.03% wt. chlorine.

Example 11 Preparation of Catalyst J YPtP _0.4 /Al ₂ O ₃ -Sn-Cl (Comparative)

Catalyst J was prepared in exactly the same way as catalyst H, but with a different (higher) target Y content, of the order of 1.2% wt. Catalyst J obtained after dechlorination contained 0.29% wt. platinum, 1.17% wt. yttrium, 0.29% wt. tin, 0.38% phosphorus and 0.98% wt. chlorine.

Example 12 Evaluation of Catalysts A1, A2 and B-J in a Catalytic Reforming Process

Samples of the catalysts, the preparation of which is described in examples 1-11, were used in the reaction layer intended for the conversion of hydrocarbon feedstock such as naphtha obtained by distillation of oil. The composition of the naphtha was as follows:

49.6% wt. paraffin compounds,

35.3% wt. naphthenes,

15.1% wt. aromatic compounds.

The total density was 0.7539 g/cm ³ . The initial and final distillation temperatures of this feed were 101 and 175°C, respectively, with 95% distillation carried out at 166°C.

The desired octane number was about 55.

After loading into the reactor, the catalysts were activated by thermal treatment in an atmosphere of pure hydrogen for 2 h at 490°C.

The evaluation of the parameters of the catalysts was carried out under the conditions of the reforming reaction in the presence of hydrogen and naphtha, described above. The conditions for using the catalyst were as follows:

- Reactor pressure 0.76 MPa (7.6 bar g)

- Raw material consumption 1.8 kg/h per kg of catalyst

- Molar ratio of hydrogen/hydrocarbons of the raw material: 3

The catalysts were compared for the same given octane number (RON) of the liquid effluent streams (reformates) resulting from the catalytic conversion of the feedstock. The comparison was made for RON=100.

Selectivity was expressed as the yield of compounds With ₅₊ in mass percent relative to the effluent at a given level of activity. During the test, the yield was characterized by the first phase, when it increased in time with the supply of raw materials, which corresponded to the selectivization of the catalyst for coke. Then, after a plateau of variable duration, the yield decreased with time. This period corresponded to the deactivation of the catalyst. Comparison of catalysts for selectivity will be performed based on yields measured in the plateau region. The measurement accuracy was +/-0.3 points. The selective catalyst is characterized by an increased yield of C ₅₊ .

Activity was expressed in terms of the temperature required to achieve a given octane number (also referred to as RON, Research Octane Number, research octane number according to English terminology). In this case, the temperature at the 24 hour test will be used. The accuracy of this measurement was +/-2°C. The active catalyst is characterized by a lower temperature required to achieve RON.

Stability refers to stable activity, usually measured as the increase in heat input to the plant required to maintain a constant RON of 100. A stable catalyst has a small increase in heat.

Catalyst Exit
C5+
(% weight.) Temperature by 24h (°C) Increasing the amount of heat in 240 h
(°C/h) A1 Pt/Al ₂ O ₃ -Sn-Cl 86.8 475 0.17 A2 Pt / Al ₂ O ₃ -Sn-P _0.4 -Cl 88.4 481 0.12 B Y _0.1 Pt / Al ₂ O ₃ -Sn-Cl 88.6 478 0.10 C Y _0.1 Pt / Al ₂ O ₃ -Sn-P _0.4 -Cl 89.0 481 0.08 D Y _0.1 Pt / Al ₂ O ₃ -Sn-P _0.8 -Cl 89.2 484 0.07 E PtY _0.1 / Al ₂ O ₃ -Sn-P _0.4 -Cl 89.0 482 0.08 F Y _0.1 Pt / Al ₂ O ₃ -Sn-P _0.3 -Cl 88.7 480 0.10 G Y _0.1 Pt / Al ₂ O ₃ -Sn-P _1.15 -Cl 88.9 486 0.06 H Y _0.5 Pt / Al ₂ O ₃ -Sn-P _0.4 -Cl 88.8 485 0.09 I Y _0.1 PtP _0.4 / Al ₂ O ₃ -Sn-Cl 89.6 480 0.07 J Y _1.2 Pt / Al ₂ O ₃ -Sn-P _0.4 -Cl 88.7 489 0.13

These results demonstrate the synergistic effect of P and Y when the phosphorus content is less than or equal to 1% wt. and the yttrium content is less than or equal to 1% wt. This effect makes it possible to increase the selectivity and stability of catalysts without sacrificing activity.

Claims (29)

1. A reforming catalyst containing a support of at least one noble metal M, tin, phosphorus and yttrium, while the phosphorus content is from 0.4 to 0.8 wt%. relative to the weight of the catalyst, the yttrium content is greater than or equal to 0.01% wt. and less than 0.5% wt. relative to the weight of the catalyst, wherein the substrate contains silicon oxide, aluminum oxide or aluminosilicate, wherein the catalyst also contains a halogen compound. 2. The catalyst according to claim. 1, in which the content of the noble metal M is from 0.02 to 2 wt%. relative to the weight of the catalyst. 3. The catalyst according to one of paragraphs. 1 or 2, wherein the noble metal M is platinum or palladium. 4. The catalyst according to one of paragraphs. 1-3, in which the tin content is from 0.005 to 10% by weight. relative to the weight of the catalyst. 5. The catalyst according to one of paragraphs. 1-4, in which the yttrium content is from 0.07 to 0.48% by weight. 6. The catalyst according to one of paragraphs. 1-5, in which the yttrium content is from 0.02 to 0.3 wt%. relative to the weight of the catalyst. 7. The catalyst according to one of paragraphs. 1-6, in which the atomic ratio Sn/M is from 0.5 to 4.0, preferably from 0.9 to 3.5, most preferably from 0.95 to 3.2. 8. The catalyst according to one of paragraphs. 1-7, wherein the P/M ratio is 0.2 to 30.0, preferably 0.5 to 20.0, more preferably 0.9 to 15.0. 9. The catalyst according to one of paragraphs. 1-8, in which the ratio Y/M is from 0.1 to 5.0, preferably from 0.2 to 3.0. 10. The catalyst according to any one of paragraphs. 1-9, in which the content of the halogen compound is from 0.1 to 8 wt%. relative to the weight of the catalyst. 11. The method of obtaining a catalyst according to one of paragraphs. 1-10, including the following successive stages, in which: a) prepare a precursor containing a substrate, tin, phosphorus and a noble metal, b) drying the precursor obtained in step a) in a neutral gas stream or in a gas stream containing oxygen at a temperature of less than 200°C and calcining at a temperature of from 350 to 650°C, c) impregnating the dried and calcined precursor obtained in step b) with an impregnation solution containing a yttrium precursor, d) drying the impregnated precursor obtained in step c) in a neutral gas stream or in a gas stream containing oxygen at a temperature of less than 200°C and calcined at a temperature of from 350 to 650°C, and halogen is added to the catalyst. 12. The method according to claim 11, wherein the halogen is added by impregnation with an aqueous solution of an appropriate acid or by oxychlorination. 13. The method according to claim 11 or 12, in which stage a) includes the following stages, in which: a1) preparing a substrate containing tin by introducing a tin precursor during the formation of the substrate, a2) impregnating the tin-containing substrate obtained in step a1) with an impregnating solution containing at least a noble metal precursor and a phosphorus precursor. 14. The method according to any one of paragraphs. 11-13, in which stage a) includes the following stages, in which: a1') prepare a substrate containing tin and phosphorus by introducing a tin precursor and a phosphorus precursor during the formation of the substrate, a2') impregnate the tin-phosphorus-containing substrate obtained in step a1') with an impregnating solution containing at least a noble metal precursor. 15. The method according to paragraphs. 11-14, in which the catalyst obtained after step d) is subjected to hydrogen treatment. 16. The use of a catalyst according to one of paragraphs. 1-10 in the process of reforming.