GB2150852A

GB2150852A - Hydrocarbon hydrotreatment process

Info

Publication number: GB2150852A
Application number: GB08431107A
Authority: GB
Inventors: Jacques Caillod; Yves Jacquin; Herve Toulhoat
Original assignee: Pro Catalyse SA
Current assignee: Pro Catalyse SA
Priority date: 1983-12-09
Filing date: 1984-12-10
Publication date: 1985-07-10
Also published as: JPS60152592A; FR2556363A1; NL8403724A; DE3444732A1; GB8431107D0; FR2556363B1

Abstract

The invention concerns a hydrocarbon hydrotreatment process, operated in the presence of a catalyst containing a carrier formed in major part of alumina and an active phase, the alumina carrier being obtained by admixing an alumina binding agent with a charge of alumina base. At least a portion of the active phase or of its precursor is introduced during the manufacture of the carrier, either into the charge, or into the binding agent or during the admixture of the charge with the binding agent.

Description

SPECIFICATION Hydrocarbon hydrotreatment process The present invention relates to a process for the hydrotreatment of hydrocarbons in the presence of an alumina catalyst containing an active phase generally comprising at least one metal from Group VIII of the Periodic Table of elements and at least one additional metal used as promoter.

Catalysts have generally been hitherto prepared in two steps: a) the carrier is prepared or obtained commercially, and b) an active phase is then deposited on the carrier.

The active phase contains generally () at least one metal usually from Group VIII of the Periodic Table of elements, generally present in the catalyst as the metal itself or for example as an oxide or sulfide, and (ss) optionally at least one so-called additional metal (or promoter) from any Group of the Periodic Table of elements, generally present in the catalyst as an oxide or sulfide for example.

According to the prior art, several methods may be used to incorporate the active phase of the catalyst into the carrier. Generally, each metal individually or all the metals together may be incorporated into the carrier by a suitable method, consisting of co-precipitation or cogelation with the porous carrier, ionic exchange with the gelled carrier, or impregnation of the carrier, either before or after drying and firing the latter.

We now provide a process for the manufacture of a catalyst comprising an active phase consisting of at least one metal of the platinum family and at least one additional metal, and a carrier obtained by admixture of a binding agent with a charge, the process comprising the following steps: 1) admixture of the charge, the binding agent and at least a portion of the active phase, 2) shaping the mixture, 3) drying and optionally firing, and 4) optional introduction of the remaining portion of the active phase, followed by drying and then activation.

In this process, the major part of the metals of the platinum family and/or the major part of the additional metals are introduced either with the binding agent or with the charge during the first step.

In the present invention, the catalyst carrier is prepared from an aqueous alumina composition. The carrier comprises the binding agent, generally constituting a dispersed part, and a charge, generally constituting a non-dispersed part of the composition. Preferably, the dispersion ratio of the composition in water, resulting from the admixture of the binding agent with the charge, ranges from about 10 to 60%. For certain uses of the catalysts, the particle size of the non-dispersed part of the composition may be further so selected that the average diameter of the alumina particles of which it is formed ranges from 1 to 15 microns, at least 70% of said particles having an average diameter between half the average diameter and twice said average diameter.

The dispersion ratio is represented by the proportion of alumina remaining in total colloidal suspension after the composition has been subjected to centrifugation. This dispersion ratio may be measured as follows: the aqueous alumina composition is diluted so asto give a total alumina concentration of 100 g/l; 100 ce of said solution are su bjected to vigorous sti rring for 10 minutes; the solution is then centrifuged for 10 minutes at 3000 r.p.m; and the settled part is separated from the unsettled part formed of alumina colloidal suspension. After firing, the settled part is weighed, and the dispersion ratio is expressed as the ratio between the initial total amount of alumina composition less the settled alumina amount, in proportion to the total initial alumina amount of the composition.

According to the present invention the dispersion ratio in water of the aqueous alumina composition is preferably 10-100%, more particularly 15-40%, the particle size of the non-dispersed part of the composition is such that the average diameter of the alumina particles of which it is formed ranges preferably from 1 to 15 microns.

The non-dispersed part of the composition generally consists of the charge; but a minor fraction thereof may come from the binding agent.

The proportion of binding agent in the composition is preferably 10-60% and more particularly 15-40% referred to the total weight of carrier. Accordingly, the weight proportion of the charge in the composition is 40-90%; more particularly 60-85%.

According to the invention, the alumina binding agent generally comprises a portion of dispersed alumina and optionally a minor portion of non-dispersed alumina, the dispersed portion amounting preferably to at least 70% by weight of the binding agent. Hereinafter, the term "binding agent" will be used to designate the dispersed portion (even if all the binding agent is not dispersed) and the term "charge" will designate the non-dispersed portion (even if a portion of the charge, smaller than 10% by weight, is in a dispersed state).

The invention provides a process for the hydrotreatment of hydrocarbons, in the presence of a catalyst comprising (a) a carrier, a major part of which is formed of alumina, and (b) an active phase, the alumina carrier used for the manufacture of the catalyst being obtained by admixture, shaping, drying and firing of an alumina binding agent and an alumina charge. The manufacture of the catalyst is characterised in that at least a portion of the active phase is introduced during the manufacture of the carrier, so that said active phase is to be found in a major part in the binding agent or in a major part in thecharge or both in the charge and in the binding agent before or during the admixture of the charge with the binding agent.The method comprises, for example, introducing at least a portion of the active phase, mostly with the binding agent or mostly with the charge during admixture of the charge with the binding agent.

According to an alternative embodiment of the process, the alumina charge (e.g. to improve thermal; stability) may be at least partially replaced with an oxide selected from oxides of magnesium, calcium, strontium, barium, scandium, yttrium, the lanthanides, gallium, indium, thallium, boron, silicon, titanium, zirconium, hafnium, thorium, germanium, tin, lead, vanadium, niobium, tantalum, chromium, molybdenum tungsten, rhenium, iron, cobalt, nickel, copper, zinc or bismuth.

The invention relates to various hydrotreatment processes of petroleum products, such as for example hydrodesulfurization, hydrodemetallation, hydrodenitrification and the like.

According to the invention, the alumina binding agent is preferably present as a powder.

The alumina binding agent should generally be gelable or coagulable by thermal or chemical action.

Gelation or coagulation by thermal action is well known in the art and may be obtained by evaporation of water from an aqueous suspension or dispersion of alumina forming the binding agent. Gelation or coagulation by chemical action is also well known in the art and may be obtained by increasing the pH of an aqueous suspension or dispersion of the alumina forming the binding agent, to more than 9, which corresponds to the isoelectric point of alumina.

Alumina binding agents used according to the invention are, for example, aqueous suspensions or dispersions of fine or ultra-fine boehmites having particles sizes within the colloidal range, i.e. lower than about 2000 .

Aqueous dispersions or suspensions of fine or ultra-fine boehmites may be obtained, as well known in the art, by peptization of these products in water or acidified water. The fine or ultra-fine boehmites used according to the invention may particularly be obtained by the process disclosed in French Patents Nos. 1 262 182 and 1 381 282 or in the European Patent Application No. 15 196.

French Patent No. 1 262 282 discloses a process for manufacturing fine or ultra-fine boehmite by heating an aqueous alumina dispersion of the presence of a monovalent acid radical, the aqueous alumina dispersion being obtained from basic aluminium chloride, basic aluminium nitrate, aluminium hydroxide, alumina gel or colloidal solutions. This product, sold on the market by Du Pont de nemours, under Trade Mark Baymal, is a fine or ultra-fine fibrillar boehmite of 250 - 350 m2/g specific surface area.

French Patent No. 1 381 282 discloses a process for manufacturing fine or ultra-fine boehmite by subjecting a suspension or cake of amorphous hydrated alumina gel, containing up to 35% by weight of alumina as AI2O3, and from 0.05 to 0.5 monovalent acid ions per mole of A1203 of said alumina to a temperature offrom 60 - 150'C for 15 hours to 10 days. The cake was obtained by drying, washing and filtering the alumina gel, continuously precipitated at a pH from 8 to 9 from a solution of sodium hydroxide aluminate and nitric acid. The specific surface area of these products generally ranges from 200 to 600 m2/g.

European Patent Application No. 15 196 discloses a process for manufacturing boehmite, at least partially as ultra-fine boehmite, by treating in an aqueous medium of pH lowerthan 9, an active alumina powder obtained by rapid dehydration of hydrargillite in a hot gas stream.

As binding agent for alumina, aqueous suspensions or dispersions obtained from pseudo-boehmite, amorphous alumina gels, aluminium hydroxide gels or ultra-fine hydrargillite, may be used. The pseudo-boehmite may be prepared according to the process disclosed in US Patent 3360 670 by reacting an alkaline aluminate solution with a solution of an inorganic acid. It may also be prepared, as disclosed in French Patent No. 1 357 830, by precipitation at pH 9 at a temperature slightly higher than room temperature, from reactants at such concentrations that about 50 g/l of alumina are obtained in the dispersion.

Amorphous alumina gels may be prepared according to the processes disclosed in "Alcoa paper" No. 19 (1972) - pages 9-12 and particularly by reacting an aluminate with acid, an aluminium salt with a base or an aluminate with an aluminium salt, by hydrolysis of basic aluminium salts or of aluminium alcoholate obtained by reacting aluminium with an alcohol.

Aluminium hydroxide gels may be those prepared according to US Patents Nos. 3268295 and 3245919.

Ultra-fine hydrargillite may be prepared according to the process disclosed in French Patent 1 373 808, by subjecting alumina gels, as cakes containing 0.10 monovalent acid ions per molecule of Awl203 of alumina, to a temperature of from room temperature to 60on.

According to an alternative embodiment of the process of the invention, the alumina binding agent may at least be partially replaced with a silica suspension or dispersion having the same characteristics as the alumina binding agent.

According to the invention, the alumina charge generally comprises a non-dispersable alumina portion optionally with a minor portion of dispersable alumina, which is dispersed in the composition, the non-dispersable portion amounting to at least 90% by weight of the charge. It may be preferable that the particle size of the non-dispersed portion of the composition is such that the average diameter of the alumina particles of which it is formed, is 1-15 microns.

The alumina charge may be any alumina compound having the above-stated characteristics, particularly hydrated alumina compounds such as: hydragillite, bayerite, boehmite, pseudo-boehmite and amorphous or substantially amorphous alumina gels, optionally in the dehydrated or partially dehydrated form of these compounds, which consist of transition aluminas and comprise at least one of the phases selected from rho, chi, eta, gamma, kappa, theta, delta and alpha aluminas.

In particular, convenient alumina charges will be those obtained by one of the following processes, optionally after crushing and screening of the particles: - An aqueous solution of an aluminium salt is precipitated with a solution of alkaline aluminate. The precipitate obtained is atomized and then suspended again in an aqueous solution of pH-4.5to 7. The resultant alumina mixture is atomized and dried; then the obtained product is washed, dried and fired (Process disclosed in US Patent 3 520 654).

- An alumina gel is precipitated at a pH of from 7.5 to 11, then washed, dried, again suspended and the product is quickly dehydrated in a hot gas stream at an inlet temperature of 350 - 1 000"C and then fired (Process disclosed in French Patent 2 221 405).

- An alumina gel is precipitated at a pH of from 7 to 10.5, the precipitate is aged at a pH of from 10 to 1 1, the mixture obtained is homogenized and atomized at 250-550oC and then fired (Process disclosed in British Patent 888 772).

- An alkaline aluminate is precipitated with an inorganic acid at a temperature of from 30 to 75 C. The resultant mixture is aged in a second reactor at 35-70"C, at a pH close to 7, recycled to the mixing reactor, and the product is filtered, washed, dried by atomizaton and fired (Process disclosed in U.S.

Patent 3 630 670.) - Aluminium hydroxides or oxyhydroxides and more particularly hydrargillite, are rapidly dehydrated in a stream of hot gases. This dehydration is performed in any convenient apparatus by a hot gas stream, the inlet temperature of the gases in the apparatus generally varying from 400 to about 1 200"C, and the contact time of the hydroxide or oxyhydroxide with the hot gases being generally from a fraction of second to 4-5 seconds. Such a process of manufacturing active alumina powder has been disclosed particularly in French Patent No.1108011.

- An active alumina powder obtained by quick dehydration of hydrargillite in a stream of hot gases, drying by atomization and then firing, is treated in an aqueous medium of pH lower than 9 (Process disclosed in the European Patent Application No. 15 196).

The alumina charges obtained according to the various processes may be cissified into two groups. The first group concerns charges obtained after drying and optionally firing, which have a certain dispersion ratio.

These products may be used without further processing for the charge, optionally after crushing and screening. The second group concerns charges obtained after drying, which have a dispersion ratio lower than that of the charges of the first group. These charges need, before use, to be fired at a temperature higher than 300"C, optionally after crushing and screening.

In the process of the invention, the binding agent and/or the alumina charge may be at least partially replaced with an oxide selected from at least one of the metals, above called promoters, or additional metals.

The charge and the binding agent may be admixed as powders. The powdered binding agent may consist of various products: boehmite, pseudo-boehmite, bayerite, amorphous alumina gels, aluminium hydroxide gels, ultra-fine hydrargillite in non-peptized state. The powder mixture is then contacted with water or acidified water. The charge-binding agent-water mixture is prepared so that the pH of the final composition is lower than 4, in such proportions that the dispersion ratio of the final composition is from 10 to 60%.

According to another method, the powdered charge and the binding agent, as an alumina suspension or dispersion, may be admixed, with stirring, in such proportions that the dispersion ratio of the composition is from 10 to 60% and the pH of the final composition is lower than 4.

The present invention is thus concerned with the use of a catalyst whose manufacture is characterized in that at least a portion of the active phase, or a precursor thereof, is introduced during the shaping of the carrier, i.e. during the admixture of the binding agent with the charge. The active phase generally comprises at least one metal from Group VIII, generally present in the catalyst as a metal per se, particularly when the catalyst is a noble metal of the platinum group, and optionally at least one other metal, generally as an oxide or sulfide, to promote the activity of the first metal. At least a portion of the active phase, as explained more in detail hereinafter, will be introduced either with the binding agent of the carrier or with the charge of the carrier or both with the charge and the binding agent.When the whole active phase is not introduced during the manufacture of the carrier, the remaining portion of the active phase will be introduced later, as in conventional methods.

More particularly, at least the portion of the active phase, or its precursor, is introduced (a) either with the charge, (ss) or with the binding agent, (w) or both with the charge and the binding agent.

Said portion of active phase may be added to the binding agent and/or to the charge during the mixture of the charge with the binding agent.

With respect to the addition of a major part of the active phase itself to the binding agent, the operation may be performed: (1) - Either by impregnation of the binding agent in a conventional way (dry or wet) by means of an acidified aqueous solution of a metal-salt or compound or of at least one metal of the active phase.

For example, one method comprises impregnating the carrier with solutions of compounds of the metals to be introduced. Either a single solution of these metals or separate solutions for each metal or each group of metals may be used.

Afirst method of manufacture comprises example impregnating the binding agent or the charge of the carrier with of an aqueous solution of a nitrate or other compound of a metal other than those from Group VIII, then a second impregnation is performed with a solution containing at least one Group VIII metal.

Another method consists, for example, of impregnating the carrier by means of a solution containing together: o) one or more metals from the Group VIII, family, and ) one or more metals other than those from Groups VIII (for example, a chloride, bromide, fluoride, sulfate or acetate of the selected metal or still any other water-soluble metal salt).

Afurther method comprises introducing the metal elements in as many successive impregnations as metal elements to be introduced in the catalyst; for example successively: - a metal from Group VIII, by means of a solution containing the same, - one or more other metals from Group VIII (when the catalyst comprises several metals) by means of a solution containing the same, and - finally the one or more other additional metals.

Of course, the order of the above-mentioned impregnations does not need to be as above stated and may be different; (2) - or by co-gelation of the alumina powder forming the binding agent with the active phase introduced as a colloidal suspension; (3) - or during the manufacture of the binding agent by co-precipitation of an alumina salt with a salt of the active phase. The binding agent is advantageously dried at a temperature lower than 300"C.

The addition of the active phase during admixture of the charge with the binding agent, preferably with introduction of the active phase in the binding agent or in the charge, may be effected: a) in several steps, or b) in a single step.

(a) In serveral steps When it is desired to introduce the active phase preferentially into the binding agent, the method comprises first introducing the binding agent in an aqueous solution, then a salt of the metal of the active phase and then the charge, previously saturated with a suitable salt, so that the salt of the active phase does not penetrate into the charge (the salt to thus block the charge may be, for example, a volatile salt such as a nitrate, chloride, sulfate, ammonium salt, amine, hydroxylamine, hydroxylamine chloride, ammonium acetate and the like).

When it is desired to introduce the active phase preferentially into the charge, the method comprises introducing the charge, then the one or more salts of the metal of the active phase, and then the binding agent blocked by a salt as above described.

(b) In a single step In order to preferentially introduce the active phase into the binding agent or into the charge, either the charge or the binding agent is blocked as above indicated with a convenient salt, the active phase being thus fixed either in the binding agent, when the charge is blocked, or in the charge, when the binding agent is blocked.

For introducing the active phase into the binding agent, the latter may preferentially have a specific surface area of about 150-600 m2/g and the charge any specific surface area but generally so selected that the ratio of the respective specific surface areas of the binding agent and the charge is higher than about 1.5. thus the salt of the active phase is preferably fixed onto the binding agent.

Conversely, for introducing the active phase into the charge, the latter may preferentially have a specific surface area of about 100-600 m2/g, the binding agent conveniently having such a specific surface area that the ratio of the respective specific surface areas of the charge and of the binding agent is higher than about 1.5.

When the active phase comprises more than one metal, it is possible to introduce separately each metal in the binding agent or in the charge by any one of the above described methods.

Simultaneously with the introduction, in one or more steps, of at least a portion of the active phase, the binding agent and the charge may be shaped by any convenient means such as for example: a) by extrusion, b) by the so-called method of bowl granulation (or revolving bowl or revolving granulator and the like), or c) by the so-called oil-drop method (drop falling into oil).

Any remaining portion of active phase may be added to the catalyst mass after shaping of the carrier.

Generally, it has been observed that the introduction into the charge of the active phase, or of a part thereof, imparts improved catalytic properties (selectivity, yield) to the final catalyst, and it has been observed that the introduction of the active phase or a portion thereof into the binding agent, imparts to the final catalyst a higher mechanical strength (particularly desirable for use in moving bed applications) and hence a longer lifetime.

Thus, according to the invention, the catalyst alumina carrier to which the active phase, consisting for example of at least one metal from Group VIII of the Periodic Table (e.g. cobalt, iron, nickel) is added, is preferably prepared by an extrusion method, by the so-called method of bowl granulation or of revolving granulation (or an equivalent method such as that of the rotary bowl and the like), or by the so-called oil-drop method, the method of manufacture being characterized in that at least a portion of the active phase is added either with the charge or with the binding agent or both with the charge and the binding agent.

Generally, the active phase contains at least one metal from Group VIII and at least one metal promoter.

Thus three preferred methods may be considered for shaping the binding agent and/or the charge and the portion of active phase during the manufacture of the carrier, depending on whether said active phase part is the Group VIII metal and/or the metal promoter.

Hereinafter, the terms "major part of the oxide" of the promoter (or of the promoter oxides, when several promoters are used) or "major part of the Group VIII metal" (or Group VIII metals when several metals are present in the catalyst) will be used. by "major part" is meant at least about 55% by weight of the total amount of oxide (or oxides, when several oxides are involved), or 55% by weight of the totality of the Group VIII metal, expressed as metal (or Group VIII metals when several metals are involved), present in the final catalyst, i.e. in the catalyst ready for use.

It will be appreciated that if all the desired metal oxide(s) promotoers and/or if all the metal or metals from Group VIII have not been introduced by the indicated method, the oxide(s) promoter(s) and/or the metals from Group VIII, not introduced by the indicated method may be introduced in the charge or at a later stage (e.g. after the manufacture of the carrier).

For the shaping of the carrier various techniques are possible.

I. In the oil-drop method of shaping the charge binding agent mixture, the metal from Group VIII may be introduced into the charge or into the binding agent but it is also possible to add it at a later stage (e.g. during the manufacture of the carrier, admixed with a portion of the active phase, in conformity with the invention) by any adequate conventional method, for example by impregnation. The promoter or additional metal, generally introduced as an oxide, may be added either to the binding agent or to the charge, or both to the binding agent and to the charge, or also, but generally in minor part, at the end of the carrier-active phase admixture, by any method, for example by impregnation.

Six operating methods (1 to 6) are preferred: Method 1; The major part of the metal oxide(s) promoter(s) is introduced with the binding agent and at least a portion, for example the major part, of the Group VIII metal(s) is introduced with the binding agent.

Method 2: The major part of the metal oxide(s) promoter(s) is introduced with the charge and at least a portion, for example the major part, of the Group VIII metal(s) is introduced into the binding agent.

It should be noted that any metal oxide(s) promoter(s) and/or Group VIII metal(s) not introduced as above indicated may be introduced into the binding agent and/orthe charge respectively or after the manufacture of the carrier. This not only applies to Methods 1 and 2 but also for Methods 3 to 6 below. It will be readily appreciated that when a minor portion of the oxide(s) promoter(s) and/or Group VIII metal(s) is not introduced in conformity with the indicated method, this or these minor portions may then be introduced in any other way.

Method 3: The major part of the metal oxide(s) promoter(s) is introduced into the binding agent and at least a part, for example the major part, of the Group VIII metal(s) is introduced into the charge.

Method 4: The major part of the oxide(s) promoter(s) is introduced into the charge and at least a part, for example the major part, of the Group VIII metal(s) is introduced into the charge.

Method 5: The major part of the oxide(s) promoter(s) is introduced into the binding agent and the Group VIII metal(s) are introduced at a later stage, after the manufacture of the carrier, for example by conventional impregnation.

Method 6: The major part of the oxide(s) promoter(s) is introduced into the charge and the Group VIII metal(s) are subsequently introduced after the manufacture of the carrier, for example by conventional impregnation.

II. When admixture is achieved by the revolving bolus granulator type method, two methods (Nos. 7 and 8) are generally selected for introducing at least part of the active phase into the carrier, particularly when the catalyst contains a Group VIII metal as promoter.

Afirst method (No. 7) comprises introducing the major part of the metal oxide(s) promoter(s) into the binding agent. A second method (No.8) comprises introducing at least a part, for example the major part, of the metal oxide(s) promoter(s) into the charge. For these two methods, the total amount of the Group VIII metal(s) is preferably introduced subsequently, after the preparation of the carrier, for example by impregnation.

III. When the carrier active phase mixture is obtained by an extrusion type method, several methods are possible which correspond to the six methods 1 to 6 described above for the oil drop technique.

In the oil drop method, drops of binding agent and charge are introduced into a liquid immiscible with water in such a manner that the drops form substantially spherical particles. These particles are simultaneously coagulated and'or subsequently made spherical with a gelling agent which removes stabilizing ligands. Also simultaneously, at least a portion of the active phase of the catalyst is added, either in the binding agent or in the charge or both in the charge and in the binding agent.

The liquid immiscible with water may be such that the drops fall (where the density of the liquid is lower than the density of the drops) or rise (where the density of the liquid is higher than the density of the drops).

Examples of such liquids which may be used in the process of the invention include crude oil, kerosene, dodecylbenzene, trichloroethylene and perchloroethylene, as well as organic solvents, hydrocarbons and inorganic oils generally.

The gelling agent which removes stabilizing ligands may for example be ammonia, an ammonia solution, ammonium carbonate, long-chain amines (particularly those sold under trade mark "Primene"), hexamethylene tetramine and urea.

The resultant drops may be recovered from the medium used for their shaping and/or coagulation.

According to a preferred embodiment, the drops of the mixture are introduced into a column containing an upper phase comprising crude oil and a lower aqueous phase comprising an ammonia solution. Shaping takes plce in the upper phase and gelation essentially in the lower phase. The temperature of the crude oil is geneally close to room temperature. The pH of the ammonia solution should be maintained above 9. The residence time of the drops in the ammonia solution is a few minutes and generally less than about 15 minutes. In these conditions, the recovered balls are sufficiently hard and are not deformed by subsequent handling.Two new advantages of the process of the invention appear particularly for the step of spheroidal shaping and gelation: the shaping is performed at room temperature and the gelation is performed very quickly, thus it is not absolutely necessary to proceed to a subsequent ageing of the balls in a basic solution, the latter having a sufficient strength, after a short residence time in the ammonia phase.

According to a second process, the drops of the mixture are introduced (suspended) in a water immiscible liquid, liable to remove water from the drops. This immiscible liquid extracts water from the drops and causes their gelation in a spheroidal shape. For example, 2-ethyl-1-hexanol or a long-chain aliphatic alcohol, sold under trade mark Octylol, may be used.

According to a third process, the mixture is admixed with at least one water-soluble monomer whose non cross-linked polymer is soluble in water or forms a gel. The resultant mixture is then dispersed, as drops, in a hot fluid medium where substantial polymerization of the monomer occurs. The monomer may be an acrylic compound of general formula:

wherein R1 is H or methyl, R2 is OR3 or NR3R4, in which R3 and R4 represent H or a hydrophilic radical, particularly a hydroalkyl radical containing 1 or 2 carbon atoms, or a methoxymethyl radical. The main steps of the process are described in French Patents No. 2 261 056 and 2 261 057.

However prepared, the balls are then separated from the gelation medium and dried and fired at a temperature of about 550-1100"C.

The resulting balls have a total pore volume of 0.30-1.7 cc/g, the micropore volume (i.e. of pores of diameter lower than 0.06 micron) being 0.5-lcc/g, and the macropore volume (i.e. of pores of diameter larger than 0.06 micron) being 0.05-0.7 cc/g. The average diameter of the macropores is generally 0.1-10 micron.

The specific surface area of the balls is about 80-350 m2/g (BET method, products dried at 1 10"C), and their breaking strength is higher than 1 kg.

In the extrusion method or the revolving granulator method the manufacture of the catalyst is carried out as follows: 1) in an optional first step, the carrier material is washed; 2) in a second step, the carrier material is dried by any appropriate method, for example by oven-drying, to obtain a powder which has the same structure as the starting material and which, after drying, is characterized by a loss on heating of about 15-40% at 1000or; 3) in an optional third step, the material is washed and dried; 4) at this stage, before the subsequent steps, it is often preferable to fire at least partially the dried powder.

Thus, 20-80% of the alumina powder may be subjected to a temperature of about 200-800"C and the fired powder can be admixed with non fired powder. Here the object is to impart to the final product a macro-porosity by means of two-phase products. More particularly it is desired in this case to obtain, after admixture of the fired powder with non-fired powder, a powder of particle size ranging from 1 to 50 microns and having a critical macro-porosity corresponding to pores of a diameter larger than about 600 ; and 5) the resultant powder is then shaped: : (a) either by extrusion, (b) or by means of a revolving bolusgranulator or by any equivalent means, this shaping being characterized by the simultaneous addition of at least a portion of the active phase into the binding agent (dispersed alumina) or into the charge (non-dispersed alumina).

The extrusion operation is as follows: For a period from 5 minutes to 5 hours, the powder is mixed in the presence of water or acidified water, the water or acidified water containing at least a portion of the catalyst active phase (i.e. metal oxides andíor precious metals).

The amount of water or of acidified water is generally 50-89% by weight of the powder weight.

The resultant paste is extruded by any convenient method, for example with a single-screw or double-screw extruding machine or any other machine, through a drawing plate.

The resultant extrudates may be dried at a temperature generally lower than 350"C so that the loss on heating of the resultant solids is about 15-40%.

At this stage, the portion of active phase not yet admixed to the carrier may be optionally and conventionally introduced and the operation terminates with a drying, for example at a temperature lower than 350"C.

Then optionally, the extrudates are subjected to a hydrothermal treatment in a neutral, acid or basic medium at a temperature of 80-500"C, so that the amorphous structures change to boehmite or pseudo-boehmite structures and lead to improved mechancial properties.

The obtained extrudates may be fired at a temperature generally from 350 to 1000"C.

The sequential order of these two latter steps may be reversed.

When operating according to the revolving granulator method or similar (bowl granulator or other: revolving plate, rotary bowl, etc...), the operation is conducted as follows: on the one hand, the powder is caused to run onto the graulator and, on the other hand, an aqueous solution or an acidified aqueous solution is simultaneously introduced by pouring or by pulverization, onto the granulator. This solution contains at least a part of the active phase of the catalyst (i.e. metal oxides and/or precious metals).

Generally, the bowl granulator or the granulator is wet while the powder rotates. The powder agglomerates by sticking of the powder particles present. The particles are removed according to usual methods, for example by ejection from the granulator by centrifugation and then they are dried and fired as above-explained for the extrusion method (with optional introduction, as above explained, of the portion of active phase not yet introduced on the carrier).

An alternative in the method would consist of feeding the granulator with a portion of powder (about 0-40% thereof) already diluted with the aqueous solution or preferably with the acidified aqueous solution. (It is so possible to dilute a portion of the powder in the acid which is used to form said acidified aqueous soluton).

The catalysts prepared according to the invention may advantageously be used in refining processes and particularly in hydrodesulfurization processes and/or other hydrotreatment processes, for example processes for converting, by hydrogenation, crude oils, liquified coals, heavy hydrocarbon fractions, as well as petroleum residues. By petroleum residues it is not only meant crude oil distillation residues but also shale oils and fractions extracted from bituminous sands.

The material to be treated may, for example, be any hydrocarbon oil of high boiling point, e.g. higherthan 350"C. The initial oil source may be any hydrocarbon fossil deposit, including, in addition to crude oil, such materials as shale oil or oily sands, or liquid hydrocarbons obtained by coal liquifaction.

Crude oil and petroleum fractions are very complex mixtures which contain in addition to hydrocarbons, various compounds containing mainly sulfur, nitrogen, oxygen, as well as metals. These compounds are present in variable amounts and are of different nature depending on the origin of the crude oil and the particular fractions. Generally, they consist of impurities detrimental to the good quality of the petroleum products, for reasons of polution, corrosion, odor, stability. Amongst the verious methods recommended for their removal, the more usual are catalytic treatments in the presence of hydrogen.

This technique has the advantage of giving products of good quality from crude oils and residues of high impurities content.

The difficulties in the treatment of the materials are mainly due to the presence of asphaltenes and metals, which under insufficiently controlled conditions, lead to deativation of the catalysts.

Contaminating metal agents may be present as oxides or sulfides; however, usually, they are present as organometallic compounds such as porphyrines and their derivatives. The more usual metals are vanadium and nickel.

Hydrocarbon materials treated acording to theinvention may be liquid hydrocarbons or hydrocarbon mixtures containing polluting elements which may be of various natures. In a particularly interesting application, relatively heavy materials such as crude oils or distillation residues containing such impurities as sulfur and/or nitrogen compounds, asphalts, organometallic or metallic compounds, may be treated. The reactions involved are those required for heavy materials of this type, particularly desulfurization, denitrification, hydrocracking, hydrogenation and demetallization.

Another type of reaction is the "hydrogenation" or treatment with hydrogen of coal, of oil shales, dissolved or dispersed in a stream of hydrocarbon solvent.

Another type is the treatment with hydrogen of used lubricating oils, for removing additives and organometallic particles therefrom and for improving, by hydrogenation, the lubricating power and the stability to oxidation and to temperature.

The conditions of the above-described reactions are usually a temperature of 270-475"C, a pressure of 20-300 bars and an hourly circulation rate of the material or of the liquid solvent of 0.1-15 volumes of catalyst, these values being not limitative and depending on the type of material and the degree of severity of the treatment performed.

The known catalysts used in similar reactions generally comprise compounds of groups VI and!or VIII metals, used as such or deposited on alumina carriers. Examples of metal compounds are oxides and preferably sulfides of molybdenum, tungsten, nickel, cobalt and/or iron and the like. The operation is conducted in fixed, moving or expanded beds, for example in fluidised beds.

Generally, catalysts with an alumina base containing a Group VIII metal and a metal promoter are prepared from a carrier consisting of a transition alumina, for example shaped as balls, extrudates, crushed materials, pellets and the like having a specific surface area of from 100 to 500 m2/g and a total pore volume of 0.2-0.9 cc/g. This alumina is then impregnated with a solution of a soluble salt, for example of nickel or cobalt, generally selected from nitrates, chlorides, formates etc., so as to give in the so-impregnated carrier from 1 to 10% by weight of nickel or cobalt, calculated as oxide. The resultant solid is then dried and fired in the presence of air, for example in an air atmosphere or under an air stream, t a temperature advantageously from 300 to 850to, for example for 0.5-6 hours.After cooling, a compound; for example a salt of a Group VIA metal, such for example as an ammonium molybdate ortungstate is incorporated, in any convenient way, for example by impregnation, mixing or coprecipitation. The total proportion by weight of the deposited metal oxides (NiO or CoO, MoOs or WO3) is preferably 5-30%. The relative proportions of oxides of metals from Groups VI and VIII may be for example as follows: for oxides of metals from Group VIII, 10-50% by weight, for oxides of metals from Group VI A, 50-90% by weight. The resultant catalyst is then dried and fired at a temperature of, for example, 400-600 C.

In some processes, the introduction of molybdenum and/or tungsten is conducted during the first firing step at 300-550"C. The second step then comprises introducing nickel and/or cobalt, the final temperature bing 400-600"C.

For hydrogenation, the catalyst may be advantageously subject to presulfurization, generally conducted "in situ". This pretreatment may be performed with a gas stream containing, in addition to hydrogen and/or an inert gas, such as for example nitrogen or methane, from 1 to 10% by volume of hydrogen sulfide, at a temperature of 200-500"C, for a sufficient time to convert at least the major part of the oxides of metals from Group VIII and from Group VIA to corresponding sulfides, i.e. for example NiO and CoO to Ni3S2 and CogS8 and MoO3 and WO3 to MoS2 and WS2.

The final catalyst will have a specific surface area generally lower than that of the starting alumina.

The invention will be further illustrated by the following non limiting Examples.

Example 7 Several catalysts with an alumina base, containing cobalt and molybdenum, have been prepared in view of subsequently testing their capacity to be used in hydrogenation reactions.

Seven catalysts (containing 3 % by weight of cobalt oxide and 14 % by weight of molybdenum oxide) are prepared according to the following methods: CatalystA: (not conforming with the invention) A catalyst is prepared by incorporating to a transition alumina carrier having a specific surface (BET) of 250m2/g and a total pore volume of 0.6 cc/g, % by weight of cobalt oxide, by impregnation from an aqueous solution of cobalt nitrate. The catalyst is then dried and roasted at 500"C for 2 hours. Subsequently, 14 % by weight of molybdenum oxide are incorporated by impregnation from a solution of ammonium paramolybdate. The catalyst is then dried and roasted at 5000C.

Catalyst B: (not conforming with the invention) An ultra-fine boehmite sol is prepared as follows: A cake of alumina gel is prepared by continuous precipitation of a sodium aluminate solution whose Al203/Na2O ratio by weight is about 1.08, at a concentration of 100 g/l, expressed as Awl203, with a nitric acid solution at such a concentration that the suspension contains about 50 g/l of alumina, expressed as Al203 and the NO3/AI203 molar ratio is 0.16. The pricipitation pH is then about 9.

The so-prepared gel cake is dried, filtered and washed. It is then treated for 24 hours at 11 50C in a shaked autoclave. The resultant product is a paste containing 12 % of alumina, expressed as A12o3.

The specific surface, measured by the BET method, of said product, dried in a stove at 110"C, is about 300 m2/g. The geometrical surface of this product, measured after drying by dispersion in isopropanol, azeotropic distillation and then evaporation of isopropanol, is about 550 m2/g.The photograph of this product, obtained with an electronic microscope, shows that it consists of ultra-fine boehmite, entirely fibrillar, composed of monocrystals shaped as elongate and very narrow lathes often forming bundles, the microcrystals having a longitudinal size of about 500 - 1000 . Along the two other directions, when considering the microcrystals as cylinders, it can be deduced from the specific surface, measured by the BET method, that these microcrystals have an average diameter of 55 . The Debye-Scherrer diagram of this product shows the absence of reflectons (nkl), a halo (012) and a clear reflection (200).

The resultant sol, which constituates the binding agent, is contacted with an amount of acidulated water so selected that the pH of the final composition be lower than 4 and that the dispersion rate of the composition be 30 %. The binding agent is admixed with a Sy alumina charge, as powder. The amounts of binding agent and charge are so selected that the resultant carrier contains, by weight, 30% of binding agent and 70 % of charge. The charge-binding agent mixture is effected as follows: Drops of the mixture of dispersed alumina (binding agent) with non dispersed alumina (charge) are formed by means of calibrated tubes of about 2.5 mm internal diameter.The drops fall into a column of 600 mm diameter containing an oil layer of about 6 cm, floating above an ammonia solution at about 20 g!l concentration. The residence time of the particles in the ammonia solution is about 2 minutes. The drops become round in the oil and gel in the ammonia solution. The recovered balls are very hard and undergo, without deformation, the transfer operations. They are then dried and calcined at 950 C for one hour. Their diameter is about 2 to 4 mm.

On the carrier so-prepared by the oil-drop method, cobalt and molybdenum are added according to the techniques indicated for catalyst A, so as to obtain the same metal contents as in catalyst A.

Catalyst C: (conforming with the invention) The manufacture of catalyst B is repeated, but with addition of ammonium paramolybdate solution at the beginning and then during the oil-drop method, this solution being introduced in the binding agent (dispersed boehmite). Cobalt is introduced subsequently, as for catalyst B.

Catalyst D: (not conforming with the invention) A sol of ultra-fine boehmite is prepared according to the technique used for catalyst B. The mixture of binding agent (dispersed boehmite) and charge (non dispersed boehmite) is extruded from its paste with water and nitric acid: Thus, a homogeneous paste is prepared after admixture, for 3 hours, on the one hand, of 500 g of alumina with, on the other hand, of a solution containing 250 cc of distilled water and 20 cc of 0.001 M nitric acid.

The paste is extruded through a drawing plate of 1.5 mm, on an extruder of the piston type.

The extrudates are dried at 300 Cso that the loss on heating of the obtained solid is about 20 %.

To the resultant catalyst mass, platinum and molybdenum are added according to the technique used for manufacturing catalyst A.

Catalyst: (conforming with the invention) The manufacture of catalyst D is repeated, but with the addition of ammonium paramolybdate solution, during the extrusion, in the binding agent (dispersed boehmite).

Cobalt is added subsequently, as for catalyst D.

Catalyst F: (not conforming with the invention) An ultra-fine boehmite sol is prepared according to the technique used for the preparation of the catalyst B. The mixture of binding agent (dispersed boehmite) and charge (non dispersed boehmite) is agglomerated by means of a revolving granulator: 500 grams of powder are poured on the granulator and simultaneously an aqueous slution, containing 250 cc of distilled water and 20 cc of 0.001 M nitric acid, is introduced on the granulator.

The granulator or bowl granulator is thus wet as the powder rotates.

The powder agglomerates by sticking of the present powder particles.

The particles are removed by ejection from the bowl granulator by centrifugation and then dried at 300 C so that the loss on heating of the obtained solids be about 20 %.

To the resultant catalyst mas, cobalt oxide and molybdenum oxide are added according to the technique used for the preparaton of catalyst A.

Catalyst G: (conforming with the invention) The manufacture of catalyst F is repeated but with adition of ammonium paramolybdate solution into the binding agent (dispersed boehmite) during the granulation. Cobalt is added subsequently, as for catalyst F.

Catalysts B to G are presulfurized, as catalyst A.

Example 2 Catalysts A to G are tested for their activity and stability in a hydrotreatment reaction. Catalysts A to G are all presulfurized, according to known techniques, before use. A straight-run residue of heavy Iran type, whose characteristics are indicated in Table 1, below, has been used in different tests, operated with the same catalyst amount and the same fresh hydrocarbon feed rate. The operation was conducted in a single stage boiling bed.

TABLE 1 Characteristics of the "Heavy Iran" straight-run residue Cut 350 C Density (d) 0.970 g/cm Sulfur (S) 2.6 % by weight Nitrogen (N) 4200 ppm (parts per million) Conradsoncarbon 10.7 % by weight Asphaltenes 4.15 % by weight Nickel 75 ppm Vanadium 200 ppm In the tests the ratio of the height to the diameter (H!D) of the reactor is 13. The total pressure is 90 bars at the reactor outlet. The hydrogen gas feed rate is 1480 liters NTP per liter of charge at 15" C. The gas is entirely injected from the bottom of the reactor, in admixture with the charge. In the tests, the average temperature is 390 C. The ratio of added catalyst to fresh charge weight is 0.6 kg/t.The ratio of the hourly fresh charge feed rate by weight to the catalyst weight is 0.83 h-1 The results are given in Table II. They show that the catalyst prepared in a conventional manner (A, B, D and F) are less active that the catalysts prepared according to the invention (C, E and G).

TABLE II

Catalyst A B C D E F G Obtained products Characteristics of the 180 C+ cut Density g/cm 0.95 0.95 0.94 0.95 0.92 0.95 0.92 Sulfur % by weight 0.93 0.92 0.80 0.90 0.65 0.90 0.59 Nitrogen ppm 3570 3560 3200 3500 3100 3550 3070 Conradson Carbon % per weight 7.0 7 6.2 7 5.7 7 5.5 Vanadium ppm 101 99 95 102 81 101 77 Vanadium % on the catalyst in pro- 16.6 16.94 17.61 16.43 19.95 16.6 20.62 portion to the fresh catalyst

Claims

1. A process for the hydrotreatment of hydrocarbons in the presence of a catalyst comprising (a) a carrier comprising a major part of alumina and, (b) an active phase comprising at least one metal from Group VIII of the Periodic Table and optionally at least one additional metal or promoter, wherein the carrier is obtained by admixing an alumina based binding agent with an alumina based charge, shaping, drying and optionally firing the resultant mixture, the proportion by weight of the binding agent amounting to 15-40% of the total carrier and the proportion by weight of the charge amounting to 60-85% of the total carrier, the alumina binding agent having a major porportion of dispersed alumina with optionally a minor proportion of non-dispersed alumina (the proportion of dispersed alumina being at least 70% by weight of said binding agent), the alumina charge having a major proportion of non-dispersed alumina with optionally a minor proportion of dispersed alumina (the proportion of dispersed alumina being less than 10% by weight of said charge), and the dispersion ratio of the composition resulting from the mixture of the binding agent with the charge being from 10 to 60%, and wherein at least a proportion of the active phase or of a precursor therefor is introduced with the charge during the preparation of the carrier and/or with the binding agent during the process of admixing the binding agent with the charge.

2. A process according to claim 1, wherein admixture of the binding agent with the charge is effected by the oil-drop method, the extrusion method or the revolving bowl granulator method.

3. A process according to either of claims 1 and 2, wherein at lest said proportion of the active phase or precursor therefor is introduced during the admixture of the charge with the binding agent, in a major part with the binding agent or in a major part with the charge.

4. A process according to any one of the preceding claims wherein at least a part of the active phase is introduced with the binding agent during admixture of the charge with the binding agent by first introducing an aqueous solution of the binding agent, then a salt of the metal of the active phase and then the charge, the charge having been saturated with a further salt so that the salt of the active phase does not penetrate into the charge.

5. A process according to any one of claims 1 to 3 wherein at least said part of the active phase is introduced with the charge during admixture of the charge with the binding agent by first introducing the charge in an aqueous solution, then a salt of the metal of the active phase and then the binding agent, the binding agent having been saturated with a further salt so that the salt of the active phase does not penetrate into the binding agent.

6. A process according to any one of claims 1 to 3 wherein a part of the active phase, the binding agent and the charge are introduced simultaneously and said part of the active phase is either introduced into the binding agent while blocking the charge with a salt, or introduced into the charge while blocking the binding agent with a suitable salt.

7. A process according to any one of the preceding claims wherein the major part of the one or more additional metals is introduced into the binding agent and the major part of the one or more Group VIII metals is introduced into the binding agent or into the charge.

8. A process according to any one of claims 1 to 6 wherein the major part of the one or more additional metals is introduced into the charge and the major part of the one or more Group VIII metals is introduced into the binding agent or into the charge.

9. A process according to any one of claims 1 to 6 wherein the major part of the one or more additional metals is introduced into the binding agent or into the charge and the major part of the one or more Group VIII metals is introduced subsequently into the carrier.

10. A process according to any one of the preceding claims substantially as herein described.

11. A process according to any one of the preceding claims substantially as herein described in any one ofthe Examples.

12. A catalyst as defined in claim 1.

13. A catalyst as defined in claim 1 substantially as herein described.

14. A catalyst as defined in claim 1 substantially as herein described in any one of the Examples.

15. Each and every novel product, process, method, apparatus and composition as herein disclosed.