FR2563120A1 - Hydrocarbon reforming catalyst and process for its manufacture - Google Patents

Abstract

a. Catalyst for reforming hydrocarbons into fractions rich in aromatic products or in antidetonating fuels, consisting of alumina agglomerates containing a small proportion of platinum and halogen. b. The catalyst consists essentially of agglomerates of gamma-aluminium oxide which has an apparent density lying between 0.40 and 0.75 kg/l, a specific surface between 160 and 280 m<2>/g and a pore volume of at least 0.50 cm<3>/g, the proportion by volume of the pores whose radius is from 2 to 10 nm being from 70 to 90 %, that of the pores whose radius is between 50 and 1000 nm from 2 to 20 % and that of the pores whose radius is between 1.5 and 4 nm from 35 to 65 % of the total pore volume. c. The catalysts according to the invention are particularly suitable for obtaining fuels of high octane number or concentrates of aromatic products.

Description

Catalyst for reforming hydrocarbons, and pro
assigned for its manufacture ".

The invention relates to a catalyst with high activity and high selectivity for the hydrocatalytic transformation of mixtures of benzene and hydrocarbons, based on an aluminum oxide offering a large surface area and porous, which can be used. , under typical reforming conditions for the manufacture of fuels as well as of aromatic product concentrates, and a process for its manufacture.

For the reforming of benzene hydrocarbon mixtures into fractions rich in cyclic combinations to obtain aromatics and fuel components, catalysts are used which contain, as main components, platinum, halogens, and a porous aluminum oxide offering a very large area.

The properties of these catalysts, in particular the stability criteria to accentuate the reaction conditions, can be improved by modification of the catalyst and have sometimes led to new generations of catalysts. In the majority of technical progress that has been made known, the improvement of catalysts has been obtained by the addition of metals or metal oxides having stabilizing and activating activity, which have led to the creation of a large number of catalytic combinations. possible. We can cite as examples the patents DD 138 509, DD 138 559,
DE-AS 1 645 715, DE-OS 2 260 697, DE-OS 2 141 420 and
DE-AS 2 044 630.

The efficiency of the catalysts can also be significantly influenced by modifying the properties of the main component aluminum oxide. Thus, catalysts are known which differ in their porosity properties. The influence of porosity, in particular pore distribution, in the catalyst, on the course of the reforming reaction is still relatively unclear at present, so the claims are partially questionable. According to DE-OS 2 141 420 and DD 138 005, advantageous effects should, for example, become possible by a high proportion of macropores in the catalyst. On the contrary, DE-OS 2 736 996 states that the proportion of macropores should be limited to a very small number and that the greatest part of the volume of the pores should be constituted by pores with a diameter of between 5 and 7 mm. In DE-OS 2 652 116, very porous catalysts are described for reforming and dehydrogenation, which have pore volumes of the order of 0.6 to 0.8 cm3 / g, and pores whose rays range up to 30 nm. Catalysts having this porosity are relatively light and unsuitable for operations on fractions containing few cyclic combinations in high power reformers. In addition, their mechanical strength is quite low, so that their use in installations with beds of mobile catalysts raises problems.

As a consequence of the complex nature of the reforming reactions, it has been described in patent DD 145 112, for the various reactors of a reformer, catalysts which are distinguished, among other things, by differences in pore distribution.

A solution of this kind is expensive as regards the preparation of the catalysts, and its general use is limited, since it cannot be used, for example, in processes where one works with a fluidized catalyst bed.

Bi- and multimetallic catalysts are also known in which the catalysis properties are improved by promoter components of different types (for example, the patent DD 145 155, DE-OS 2 360 987, DE-OS 2 233 651, the DD patents 101 379,
DD 112 467 and DD 106 863). Specific effects are frequently described from the point of view of the course of the reaction, obtained by determined combinations of catalysts, in which one mentions, alongside effects promoting activity, effects damping this activity (for example DE -OS 2,162,442). In many cases, bi-metallic catalysts require special treatments to suppress non-selective fission reactions.

For the manufacture of reforming catalysts, proven impregnation processes consist in the deposition of active components, in highly dispersed form, on castings of aluminum oxide. with a very large and porous surface. A homogeneous distribution of the active components which are present in a relatively low concentration on the aluminum oxide parts can be achieved by means of co-adsorbents such as haloacids, or by additions of lead and tin compounds to the controlled fixation of a platinum compound on aluminum oxide (patent DD 125 758). For these latter additives, it was possible to observe a direct unfavorable effect on the catalytic properties of platinum.

(3. Catal. 68, 42-50 (1981). The elimination of the so-called chromatographic effect raises problems especially in the manufacture of bi and multimetallic catalysts. In various technical studies, it has been used to ensure a homogeneous distribution of components, additives foreign to the system, for example, weak organic acids (US patent 2,222,553 ammonium hydroxide or lower alkylamines (US patent 3,976,560) or also amino alcohols (US Patent 3,976,650).

In US Pat. No. 018,201 a platinum-rhenium-copper catalyst is disclosed, the recommended catalytic properties of which are obtained by means of an expensive manufacturing process, which comprises a multistage impregnation with interleaved neutralizations. In the use of additives foreign to the system, one cannot exclude unfavorable effects on the platinum contained in the catalyst.

The object of the invention is to provide an improved catalyst for the reforming of benzene-hydrocarbon mixtures, based on aluminum oxide, which is distinguished by its high activity and selectivity, and which meets the requirements of mechanical stability. at the same time, the subject of the invention is a process for the manufacture of this catalyst.

This is to provide a catalyst for the hydrocatalytic reforming of benzene, based on aluminum oxide, which allows the quality of the properties of use to be increased by an appropriate porosity of the aluminum oxide component.

The problem also consists in developing a process for the manufacture of a catalyst for reforming hydrocarbons, by which catalysts are formed which are distinguished by the use of a smaller quantity of material, and at the same time. time by achieving more advantageous economic conditions in reforming operations.

To this end, the invention provides a catalyst for the reforming of hydrocarbons under typical reforming conditions to manufacture hydrocarbon fractions rich in aromatics or anti-detonating fuel components, consisting of agglomerates of carbon dioxide. aluminum containing at least 0.1 to 1 X mass of platinum, 0.1 to 3 X mass of halogen, as well as optionally other promoter components, preferably from VI to VIII subgroups, and / or of
IV group of the Periodic Table of the Elements, always in an order of magnitude of 0.01 to 1% by mass, catalyst characterized in that it consists essentially of agglomerates of aluminum-gamma oxide having an apparent density between 0.40 and 0.75 kg / l, 2 a specific surface area between 160 and 280 m / g, and a
3 pore volume of at least 0.50 cm3 / g, the proportion by volume of pores whose radius is from 2 to 10 nm being 70 to 90%, that of pores whose radius is between 50 and 1000 nm, from 2 to 20 X, and that of pores with a radius between 1.5 and 4 nm, from 35 to 65 X of the total pore volume.

In a recommended embodiment of the catalyst according to the invention, the proportion by volume of the pores whose radii are from 50 to 1000 nm is between 3 and 10 X and that of the pores whose radii are from 1.5 to 3 nm, between 15 and 40 X, calculated on the total pore volume. It has also been shown to be very advantageous that the catalyst according to the invention exhibits, in the field of pores with a radius of 1.5 to 2.5 nm, a proportion of the volume of the pores which is between 5 and 25 X To achieve this result, the invention provides a process for the manufacture of a catalyst for the reforming of hydrorefined fractions of hydrocarbons at temperatures between 720 and 820 K, and under pressures between 1 and 4 MPa, in the presence of gases containing hydrogen, using agglomerates of aluminum oxide gamma, the aluminum oxide precursors being made by a continuous reaction, and in two stages, of solutions of aluminum salt and aluminate of sodium giving a boehmite hydrogel, at temperatures of 323 to 363 K, and at pH of 7 to 8.5, the catalyst containing 0.1 to 1 X mass of platinum, and / or 0.1 to 1 X mass of rhenium and 0.1 to 3 X mass of halogen, as well as at least one of the elements chromium, molybdenum, tungsten, copper, silver, ga llium, silicon and iridium, in a proportion of 0.001 to 1 X by mass, a method characterized in that at least the components platinum, rhenium and halogen are applied, in an impregnation step, to the agglomerates of oxide of aluminum, the latter being treated, before and / or during the impregnation step, with soluble aluminum compounds, corresponding to an aluminum proportion of 0.1 to 5 X by mass, at pHs of 1 to 4.5 for at least 30 minutes, the impregnation solution having an alkaline content of between 0.3 and 30 mi'lli-gram-equivalents.

It is on the other hand advantageous that substantially all the components are applied during the impregnation step, that the treatment with the aluminum compounds takes place during this impregnation step and that the impregnation solution has levels
sodium between 1 and 20 m / gr / equi. It is also advantageous that during the manufacture of the aluminum oxide precursor, aluminum oxide contents are adjusted in the reaction medium from 30 to 90, or better still from 40 to 70 g / of A1203, and that the residence times of the reaction mixture in the first stage amount to a maximum of 30 minutes, and in the second stage to 30 to 240 minutes.

The manufacture of the aluminum oxide precursor is very important for the production of the catalyst according to the invention. The Boehmite hydrogels thus produced can be washed to a large extent free of alkali, without undue expense, and can be shaped, after drying and grinding, without raising problems, into agglomerates of suitable size. The catalysts produced on the basis of these agglomerates exhibit a pore distribution which is associated, surprisingly, with a particular catalytic activity.

The catalysts according to the invention are characterized, by virtue of the special method of manufacturing the aluminum oxide precursor, by a very wide distribution of the volume of the pores in a range of radii from 1 to 10 nm and thus differ significantly from catalysts of similar composition, which exhibit a relatively narrow pore distribution curve; this dominant proportion of the pore volume in the region of pore radii between 1 and 10, as well as the simultaneous presence of pores with radii greater than 50 nm are obviously associated with particular catalytic effects, and very advantageously influence the properties of the reforming catalyst. It is essential to draw attention to the fact that the aluminum oxide component of the catalyst according to the invention consists of practically pure gamma aluminum oxide from which a series of advantages emerge to the point of view of the mechanical resistance and the possibilities of technical realization of the catalyst. Besides platinum, in amounts which will preferably be 0.25 to 0.60% by mass, as well as halogens, preferably chlorine in a proportion of 0.5 to 1.5% by mass, the Catalysts according to the invention contain in particular rhenium, in proportions of 0.1 to 0.60 by weight.

As other components having a promoting and stabilizing action, the catalysts may optionally contain components of the VIth to VIIIth subgroups as well as of the IVth group of the Periodic Table of the Elements; the elements chromium, molybdenum, iridium, tin and / or lead, at concentrations which lie between 0.01 and 1 X mass having proved particularly suitable in the catalyst. For the manufacture according to the invention, the art and manner of the impregnation are also important.

It has been found to be advantageous that substantially all of the components are applied during the impregnation step, that the treatment with the aluminum compounds takes place during this impregnation step at a pH between 1 and 4.5 and that the impregnation solution has sodium contents between 1 and 20 milli-gram-equivalents.

When the impregnation is complete, the catalyst agglomerates are dried in a known manner, and treated at temperatures above 670 K, in an oxidizing atmosphere, for at least 1 hour.

The aluminum-gamma oxide agglomerates can be used in the form of rods or hollow bars or in the form of spherical particles.

According to the invention, aluminum chloride, nitrate, sulphate or acetylacetonate are suitable as compounds of aluminum. However, it has been found that the use of aluminum chloride is particularly advantageous, because with this compound it is possible at the same time to adjust the chlorine content required in the catalyst, which should advantageously be from 0.5 to 2 X of the mass.

It was surprised to note that the use of the impregnation process according to the invention leads, in particular, to obtaining very advantageous properties for the catalyst if the agglomerates of aluminum-gamma oxide used exhibit, with a pore volume greater than 0.45 cm / g, a relatively wide pore volume distribution for pores with radii less than 10 nm. This distribution is characterized by a proportion by volume of the pores of 70 to 90% for the range of pore radii from 2 to 10 nm, from 35 to 65% for the range of pore radii from 1.5 to 4 nm. , and from 15 to 40 X for the range of pore radii from 1.5 to 3 nm. It is advantageous to proceed, before putting them into service for the reforming of hydrocarbons, to a reduction of the catalysts produced, with hydrogen, at temperatures between 720 and 920 K.

The manufacturing process according to the invention ensures that all the components of the catalyst are distributed uniformly over the entire cross section of the agglomerate, and that, therefore, the specific activity of each of these components, for the hydrocarbons which are to react , is assured. The homogeneity of the distribution of the components can easily be shown by analysis using an electron beam micro-probe. In addition, the process described causes an intense action of exchange between the aluminum oxide and the active components and allows the manufacture of particularly selective and stable catalysts, which offer, in comparison with catalysts according to the prior state of the art. technically, more advantageous properties of use. The catalysts according to the invention are also remarkably suitable for the formation of aromatic products from special fractions of hydrocarbons, and can also find their use also in the operations of treatment with continuous regeneration of the catalyst, due to their remarkable stability to regeneration.

Examples of realization
Example 1
The reforming catalysts A and B are examined in a test catalyst for the reforming of a hydrorefined benzene, the boiling field of which is 110 to 1800C, in a comparative manner.

The two catalysts are in the form of agglomerate strips with a diameter of 1.4 mm, and both contain 0.35 X mass of
Pt, 0.35 mass% of Re, and 1.1 mass X of C1 and are further characterized by the following digits
Catalyst A Catalyst B
Apparent density kg / l 0.58 0.62 surface m / g 243 220 pore volume cm / g 0.60 0.58 fraction for rp: 2 to 10 nm% 81 93 fraction for r: 1.5 to 4 nm X 57 32 p fraction for rp: 1.5 to 3 nm X 35 10 fraction for r: 1.5 to 2.5 nm X 21 4 p fraction for r: 50 to 1000 nm X 7 2 p
Catalyst A characterizes a catalyst according to the invention.

The catalysis test was carried out under the following conditions
Pressure MPa 2,5 load v / vh 2 H2 / KM ratio 6 temperature OC 460 - 510 quantity of catalyst cm3 150 characteristics of gasoline boiling zone 110 to 1800C
Aromatic products 12 vol. X
Naphthene 24.5 vol X
Paraffin 63.5 XX
Sulfur less than 1 ppm
The following results were obtained
Catalyst A Catalyst B
Temperature K 761 770
ROZ-O octane number 97 96.5
Mass reformate-X yield 87.5 86.5
Mass hydrogen X yield 1.95 1.8
Example 2
Agglomerates of aluminum oxide gamma with a diameter of 1.5 mm and the following porosity characteristics 3
Pore volume 0.58 cm proportion of pores with radius 2 to 10 nm 83% proportion of pores with radius 1.5 to 4 nm 55 X proportion of pores with radius 1.5 to 3 nm 30% were covered with an impregnation solution which exhibited the following contents, calculated on the quantity of A1203 used - 0.3 X of the mass of platinum - in the form of hexa acid
chloroplatinic, - 0.3 X of the mass of rhenium in the form of acid
perrhenic, - 0.3 X of the mass of chromium in the form of chro acid
mi that, - 0.5% of the mass of aluminum in the form of chloride
aluminum, - 0.5% of the mass of chlorine in the acid form
hydrochloric.

The solution contained more than 6m / r / equi.

of sodium chloride. After two hours of impregnation, during which time the pH of the solution rose from 1.4 to 4.1, the excess solution was drained off, and the catalyst was calcined at 790 K. , after air drying for two hours. It had the following composition (calculated on A1203):
platinum 0.30 X - mass
rhenium 0.29 mass%
chromium 0.03 X mass
chlorine 1.2% by mass
The homogeneity of the distribution of all the components could be verified by means of a beam microanalysis.

electronic. A comparison catalyst having the same composition, for the preparation of which the impregnation solution was free of acalins and did not contain aluminum, was produced on the basis of the aluminum oxide agglomerates mentioned. It was possible to observe by micro-analysis with an electron beam, that, in this comparative catalyst, the platinum was depleted, in the center of the agglomerates in a proportion of up to 30%, while the other constituent parts exhibited an equally homogeneous distribution.

A comparative verification of the catalysis, under typical reforming conditions, in a test apparatus of small dimensions, with a volume of catalyst of 100 ml showed that the catalyst produced according to the invention required, in order to reach a level of corresponding quality ROZ-O 98-100, a reaction temperature of 5 to 80K lower than the comparative catalyst.On the other hand, the following other advantages of the catalyst produced according to the invention have emerged
1 to 1.3% by mass increase in liquid yield,
30 to 40% longer catalyst efficiency,
Example 3
According to the state of the art, a solution of aluminum nitrate (100 g A1203 / l; 30 9 free HN03 / l), at 750 ° C., and at a pH of 7.2, was transformed into a Boehmite hydrogel. , by adding a 25% ammonia solution. The reaction was carried out continuously in a stirred vessel, into which were introduced, dosing them, per hour, 700 l of aluminum nitrate solution and about 300 l of ammoniacal solution. By supplying water, the concentration was adjusted to 30 g of A1203/1. The suspension was diluted, after about 15 minutes, with water, to a solids content of 15. g AlzO3 / l, filtered through a filter press, the separated hydrogel was washed and then dried at about 1500C. After crushing it, the hydrogel was triturated with water into a plastic mass, which was pressed, by means of an extruder, into strips of about 1.5 mm in diameter, then dried. and calcined at about 6000C for 3 hours. From a solution in which they were immersed, the rods were impregnated with hexachloroplatinic acid and hydrochloric acid, so that the catalyst after calcination in air at 5000C contained 0.5% by mass of platinum and 0.95% by mass of chlorine.

Examination of the porosity gave the following results: pore volume 0.54 cm3 / g proportion for rp: 2 to 10 nm 96% proportion for rp: 1.5 to 3 nm 12% proportion for rp: 1.5 at 2.5 nm 5% proportion for r: 50 at 1000 nm 2% p area 215 m / g
Example 4
I1 was manufactured a catalyst according to the invention, as follows
The aluminum nitrate solution mentioned in Example 3 was transformed into boehmite hydrogel with a sodium aluminate solution (310 g of A1203 / 1: 370 g of NaOH / l), at a temperature of 700C and at a pH of 7.6.The reaction was carried out continuously, in two reaction tanks mounted one after the other in which it arrived, per hour, about 700 1 of solution of aluminum nitrate and 500 1 of sodium aluminate solution. By adding water to the first reaction vessel, a concentration of 52 A1203 / 1 was maintained, and an average residence time of the reaction mixture of 6 minutes in the first step, and 140 minutes in the second step. .

The suspension was filtered through a filter press, the separated hydrogel was washed with water, dried at about 1500C, then ground. As in Example 2, the material obtained was pressed into extruded rods of about 1.4 mm in diameter, and, after calcination, impregnated, in the same way, with platinum and chlorine.

Examination of the porosity gave the following results
Pore volume 0.56 / g proportion for r: 2 to 10 nm 83 X p proportion for r: 1.5 to 3 nm 25% p proportion for rp: 1.5 to 2.5 nm 13% proportion for rp 50 at 1000 nm 5 X area 235 m2 / 9
Example 4 shows the more advantageous distribution of the pore volume of a catalyst according to the invention.

Claims (6)

10) Catalyst for reforming hydrocarbons under typical reforming conditions to make hydrocarbon fractions rich in aromatics or anti-detonating fuel components, consisting of aluminum oxide agglomerates containing at least 0.1 at 1% by mass of platinum, 0.1 to 3% by mass of halogen, as well as possibly other promoter components, preferably from VI to VIII subgroups, and / or from the IV group of the periodic table elements, always in an order of magnitude of 0.01 to 1% by mass, catalyst characterized in that it consists essentially of agglomerates of aluminum-gamma oxide having an apparent density of between 0.40 and 0.75 kg / l, a specific surface area between 2 160 and 280 m / g, and a pore volume of at least 0.50 cm / g the proportion by volume of pores with a radius of 2 to 10 nm being from 70 to 90 X, that of the pores whose radius is between 50 and 1000 nm, from 2 to 20%, and that of the pores whose radius is between 1.5 and 4 nm, 35-65% of the total pore volume. 20) Catalyst according to claim 1, characterized in that the proportion of the pores whose radii are between 1.5 and 3 nm is from 15 to 40% and that of the pores whose radii are between 50 and 1000 nm amounts to 3 to 10% of the total pore volume. 30) Catalyst according to one of claims 1 and 2, characterized in that the proportion of the volume of the pores whose radii are from 1.5 to 2.5 nm amounts to 5 to 25% of the total volume of the pores. 40) Process for the manufacture of a catalyst for the reforming of hydrorefined fractions of hydrocarbons at temperatures between 720 and 820 K, and under pressures between 1 and 4 MPa, in the presence of gas containing hydrogen, using aluminum-gamma oxide agglomerates, the aluminum oxide precursors being produced by a continuous reaction, and in two stages, of solutions of aluminum salt and sodium aluminate giving a boehmite hydrogel, at temperatures of 323 to 363 K, and at pH of 7 to 8.5, the catalyst containing 0.1 to 1% by mass of platinum, and / or 0.1 to 1% by mass of rhenium and 0, 1 to 3% by mass of halogen, as well as at least one of the elements chromium, molybdenum, tungsten, copper, silver, gallium, silicon and iridium, in a proportion of 0.001 to 1% by mass, process characterized in that 'at least the platinum, rhenium and halogen components are applied, in an impregnation step, to the aluminum oxide agglomerates, the latter being both treated, before and / or during the impregnation step, with soluble aluminum compounds, corresponding to an aluminum proportion of 0.1 to 5 X mass, at pH of 1 to 4.5 for at least 30 minutes, the impregnation solution having an alkaline content of between 0.3 and 30 nill-gram-equivalents. 50) A method according to claim 4, characterized in that substantially all the components are applied during the impregnation step, that the treatment with the aluminum compounds takes place during this impregnation step and that the solution of impregnation has sodium contents between 1 and 20m / gr / equi. 60) A method according to claim 4, characterized in that, during the manufacture of the aluminum oxide precursor, is adjusted in the reaction medium, aluminum oxide contents from 30 to 90, or better from 40 to 70 g / l of A1203, and that the residence times of the reaction mixture in the first stage amount to a maximum of 30 minutes ,. and in the second stage at 30 to 240 minutes.