EP0153891B1 - Catalytic reforming process - Google Patents

Description

In the field of catalytic reforming or reactions for the production of aromatic hydrocarbons, the impact brought by alumina catalysts containing, in addition to a noble metal from group VIII (generally platinum), a promoter metal which is the rhenium (US-A-3,415,737). New races of catalyst are also known based on a noble metal from group VIII (generally platinum) and containing as promoter, for example tin or indium or thallium as promoter metal ( US-A-3,700,588 US-A-2,814,599).

These catalysts have been tested and used over very long periods, of the order of the year for example, and it has been found that the platinum-rhenium catalyst has excellent stability but does not allow maximum selectivity to be observed. in obtaining good quality essences. Conversely, the platinum-tin, or platinum-indium or platinum-thallium catalysts make it possible to obtain excellent selectivity, but the stability of these catalysts leaves something to be desired.

It therefore seemed advisable to use catalysts containing, in addition to platinum, the two promoters at the same time, for example rhenium and tin (US-A-3,702,294). However, with this type of catalyst, it has in fact turned out on the one hand that the selectivity of this type of catalyst remains lower than that obtained with a platinum-tin or platinum-indium or platinum-thallium catalyst and on the other hand except that the stability of this catalyst also proved to be less good than that of the platinum-rhenium catalyst.

The object of the invention makes it possible to obtain quality gasolines for long periods (therefore with good stability), with very satisfactory selectivity by putting the charge first in contact with a platinum-rhenium catalyst and then with contact with a platinum catalyst, containing at least one promoter metal chosen from the group consisting of tin, indium and thallium.

• (a) un support à base d'alumine.
• (b) 0,05 à 0,6% en poids de platine par rapport au support et de préférence 0,1 à 0,5%.
• (c) 0,005 à 3% en poids de rhénium par rapport au support, de préférence 0,07 à 2% et plus particulièrement 0,1 à 0,5%.
• (d) 0,1 à 15% d'au moins un halogène en poids par rapport au support par exemple le chlore ou le fluor,

les catalyseurs de l'autre lit ou des autres lits fixes (identiques ou différents) renfermant:

• (a) un support à base d'alumine.
• (b) 0,05 à 0,6% en poids de platine par rapport au support et de préférence 0,1 à 0,5%.
• (c) 0,05 à 3% en poids d'au moins un métal promoteur choisi parmi l'étain l'indium le thallium, de préférence 0,07 à 2% et en particulier 0,1 à 0,6%, avec éventuellement ajout de 0,005 à 0,3% d'iridium.
• et (d) 0,1 à 15% d'au moins un halogène en poids par rapport au support, par exemple du chlore et du fluor,

la proportion pondérale du catalyseur renfermant du rhénium étant comprise entre 8 et 40% et de préférence entre 10 et 20% par rapport à la masse totale catalytique utilisée dans l'ensemble des lits catalytiques.The process of the invention consists in circulating a charge successively through at least two fixed catalyst beds, the catalyst of the first bed crossed by the charge (possibly also the catalyst of the second bed crossed by the charge) containing:

• (a) an alumina-based support.
• (b) 0.05 to 0.6% by weight of platinum relative to the support and preferably 0.1 to 0.5%.
• (c) 0.005 to 3% by weight of rhenium relative to the support, preferably 0.07 to 2% and more particularly 0.1 to 0.5%.
• (d) 0.1 to 15% of at least one halogen by weight relative to the support, for example chlorine or fluorine,

the catalysts of the other bed or of the other fixed beds (identical or different) containing:

• (a) an alumina-based support.
• (b) 0.05 to 0.6% by weight of platinum relative to the support and preferably 0.1 to 0.5%.
• (c) 0.05 to 3% by weight of at least one promoter metal chosen from tin indium thallium, preferably 0.07 to 2% and in particular 0.1 to 0.6%, with optionally addition of 0.005 to 0.3% iridium.
• and (d) 0.1 to 15% of at least one halogen by weight relative to the support, for example chlorine and fluorine,

the weight proportion of the catalyst containing rhenium being between 8 and 40% and preferably between 10 and 20% relative to the total catalytic mass used in all of the catalytic beds.

By way of example, a single reactor could be used comprising at least three separate catalyst beds, the first fixed catalytic bed through which the feedstock passes (upper bed in the case of a charge downdraft or lower bed in the case of '' an ascending charge current) consisting of the platinum and rhenium catalyst, the other beds consisting of catalyst containing platinum and at least one promoter metal chosen from thallium, indium and tin: these so-called other beds may each contain a different promoter.

Still by way of example, it is possible to use at least two reactors in series, with fixed beds, placed side by side or superimposed, the first fixed bed reactor crossed by the charge containing one or more beds of the platinum and rhenium catalyst. , the other reactor (s) containing one or more beds of catalyst containing platinum and at least one other identical or different promoter metal.

One can thus imagine all kinds of catalytic bed arrangements in series, the essentials according to the invention being that the charge first passes through at least one bed of platinum and rhenium catalyst.

• - du platine et de l'étain
• - du platine et de l'indium
• - du platine et du thallium
• - du platine, de l'iridium et de l'indium
• - du platine, de l'iridium et de l'étain

It will be possible to use in catalytic zones other than that or those which contains platinum and rhenium,

• - platinum and tin
• - platinum and indium
• - platinum and thallium
• - platinum, iridium and indium
• - platinum, iridium and tin

Preferably, platinum-tin is used, or else platinum, iridium and indium.

If there are several beds (at least two beds) of a catalyst containing platinum, said metal or said promoter metals and possibly iridium, the same catalyst can be used in these beds but also different catalysts in each of these beds. Thus, these different catalysts can be differentiated by the metallic concentration of platinum, of promoters, of iridium, by the nature of the promoter, by the presence or not of iridium, by the concentration of halogen, etc.

In reforming reactions, the lack of selectivity generally results in a poor yield in the dehydrogenation of naphthenes into aromatic hydrocarbons, by a parasitic cracking of paraffins with secondary formation of olefinic hydrocarbons which will be at the origin of the formation of coke. The present process makes it possible to dehydrogenate as much as possible the naphthenic hydrocarbons into aromatic hydrocarbons, to minimize the cracking of paraffins and thus not to obtain light hydrocarbons but on the contrary to also transform them as much as aromatic hydrocarbons. Thus in accordance with the invention in the first reaction zone where an excellent stability catalyst is used. One proceeds essentially to the dehydrogenation of hydrocarbons, in particular naphthenes in aromatic hydrocarbons and in the other reaction zones, because of the selectivity allowed by the appropriate choice of a catalyst, one proceeds in particular to reactions of cyclization of paraffins without breaking them.

Example 1

• distillation ASTM : 90 - 1600 C
• densité à 15° C: 0,741
• composition :
• hydrocarbures paraffiniques : 62% en volume
• hydrocarbures naphténiques : 27% en volume
• hydrocarbures aromatiques : 11% en volume

A load having the following characteristics is treated:

• ASTM distillation: 90 - 1600 C
• density at 15 ° C: 0.741
• composition:
• paraffinic hydrocarbons: 62% by volume
• naphthenic hydrocarbons: 27% by volume
• aromatic hydrocarbons: 11% by volume

• Pression : 7 bars
• Température : 500°C
• H₂/HC_(molaire) ²
• Débit horaire de charge liquide : 3 fois le volume total de catalyseur

The feed is treated with hydrogen under operating conditions equivalent, for the catalysts used, to accelerated aging tests, these conditions being as follows:

• Pressure: 7 bars
• Temperature: 500 ° C
• H ₂ / HC _(molar) ²
• Hourly liquid charge flow: 3 times the total volume of catalyst

The charge flows successively through three reactors in series, with fixed catalyst beds, the first reactor containing a catalyst A and the second and third reactors each containing the same amount of catalyst B.

• 0,4% de platine
• 0,1% d'iridium
• 0,2% d'indium
• et 1,12% de chlore

Catalyst A represents by weight 15% of the total quantities of catalyst used in the three reactors (catalyst B therefore representing 85% by weight of the total catalytic mass). Catalyst A contains by weight 0.4% of platinum and 0.3% of rhenium relative to the support of the catalyst which is an alumina having a specific surface of 240 m ² / g and a pore volume of 0.57 cm ³ / g. Catalyst A also contains 1.12% chlorine (the specific surface and the pore volume of catalyst A are 230 m ² / g and 0.54 cm ³ / g respectively). Catalyst B contains the same alumina support as catalyst A and contains by weight relative to this support:

• 0.4% platinum
• 0.1% iridium
• 0.2% indium
• and 1.12% chlorine

(The specific surface and the pore volume of catalyst B are respectively 230 m ² / g and 0.54 cm ³ / g).

The following table 1, column 1, gives the overall "material" balance obtained after 100 hours of operation. Also given in this table, for comparison, in column 1, the material balance obtained by using the only catalyst B in the three reactors.

• (1) Utilisation du catalyseur A (platine-rhénium) dans les trois réacteurs (tracé ou courbe (1)).
• (2) Utilisation dans les trois réacteurs d'un catalyseur à base de l'alumine utilisée précédemment renfermant: (tracé(2))
  • 0,4% de platine
  • 0,15% de rhénium
  • 0,15% d'étain
  • 1,12% de chlore
• (3) Utilisation dans les trois réacteurs du catalyseur B (platine-indium-iridium) (tracé (3))
• (4) Utilisation selon l'invention, du catalyseur A (platine-rhénium) dans le premier réacteur et du catalyseur B (platine-indium-iridium) dans les deux autres réacteurs. (répartition pondérale : 15% de catalyseur A et 85% de catalyseur B) (tracé (4)).
  

In FIGS. 1 and 2, the octane number of Research of the C ₅ ⁺ reformate and the hydrogen yield (% by weight relative to the charge), as a function of time, are given respectively for four tests:

• (1) Use of catalyst A (platinum-rhenium) in the three reactors (trace or curve (1)).
• (2) Use in the three reactors of a catalyst based on the alumina used previously containing: (trace (2))
  • 0.4% platinum
  • 0.15% rhenium
  • 0.15% tin
  • 1.12% chlorine
• (3) Use in the three reactors of catalyst B (platinum-indium-iridium) (trace (3))
• (4) Use according to the invention, of catalyst A (platinum-rhenium) in the first reactor and of catalyst B (platinum-indium-iridium) in the two other reactors. (weight distribution: 15% of catalyst A and 85% of catalyst B) (trace (4)).
  

It will be noted that in this example, by using Pt-Re in all the reactors, an excellent NOR C ₅ + (curve 1 of FIG. 1) is obtained but an unsatisfactory hydrogen yield (curve 1 of FIG. 2); that the use of Pt-Re-Sn improves (compared to Pt-Re) the hydrogen yield (curve 2 in Figure 2) to the detriment of a significant reduction (still compared to Pt-Re) of NOR C ₅ ⁺ (curve 2 in FIG. 1); that the use of Pt-Ir-In gives an excellent hydrogen yield (curve 3 in FIG. 2) but in return leads to a NOR C _s ^{+ that is} too low (curve 3 in FIG. 1); but that the choice then of a Pt-Re catalyst in the first reactor (catalyst which we have seen above give a poor yield of hydrogen) used together with a Pt-Ir-In catalyst in the two other reactors ( catalyst which we have seen above give a disappointing NOR C ₅ ⁺ ) makes it possible to obtain on the one hand a very satisfactory NOR C ₅ ⁺ (curve 4 of FIG. 1) but also a very satisfactory yield of hydrogen ( curve 4 of figure 2).

Example 2

• 0,4% de platine
• 0,3% d'étain
• et 1,12% de chlore

The procedure is as in Example 1, replacing catalyst B (Pt - In - Ir) with catalyst C containing:

• 0.4% platinum
• 0.3% tin
• and 1.12% chlorine

• Courbe (1) avec le catalyseur A(Pt-Re déjà employé dans l'exemple 1) utilisé dans les trois réacteurs.
• Courbe (2) avec le catalyseur Pt-Re-Sn (déjà employé dans l'exemple 1) utilisé dans les trois réacteurs.
• Courbe (3) avec le catalyseur C (Pt-Sn) utilisé dans les trois réacteurs.
• Courbes (4) avec utilisation successive du catalyseur A (dans le premier réacteur) et du catalyseur C dans les deux autres réacteurs (le catalyseur A représentant 15% en poids de la masse catalytique totale).

The octane number and the hydrogen yield are given respectively in FIGS. 3 and 4 as a function of time:

• Curve (1) with catalyst A (Pt-Re already used in Example 1) used in the three reactors.
• Curve (2) with the Pt-Re-Sn catalyst (already used in Example 1) used in the three reactors.
• Curve (3) with catalyst C (Pt-Sn) used in the three reactors.
• Curves (4) with successive use of catalyst A (in the first reactor) and catalyst C in the two other reactors (catalyst A representing 15% by weight of the total catalytic mass).

It will be noted in this example that by using Pt-Re in all the reactors, an excellent NOR C ₅ ⁺ is obtained (curve 1 in FIG. 3) but a disappointing hydrogen yield (curve 1 in FIG. 4); that, as in the previous paragraph, the use of Pt-Re-Sn improves (compared to Pt-Re) the hydrogen yield (curve 2 in Figure 4) to the detriment of a significant reduction (always compared to Pt -Re) of NOR C ₅ ⁺ (curve 2 of Figure 3); that the use of Pt-Sn gives an excellent hydrogen yield (curve 3 in FIG. 4) but in return gives an insufficient NOR C ₅ + yield (curve 3 in FIG. 3); but that the choice then of a Pt-Re catalyst in the first reactor (catalyst which we have seen above give a poor yield of hydrogen) used jointly with a Pt-Sn catalyst in the two other reactors (catalyst which we have seen lead to a poor NOR C ₅ + yield) makes it possible, on the one hand, to obtain a very satisfactory NOR C ₅ ⁺ (curve 4 in FIG. 3) but also a high hydrogen yield (curve 4 of Figure 4).

Claims (9)

1. - A catalytic reforming process wherein a charge is circulated successively through at least two catalyst beds, said process being characterized in that the catalyst of the first bed wherethrough passes the charge comprises a carrier of alumina base and, by weight in proportion to the carrier, 0.05 - 0.6 % of platinum, 0.005 - 3 % of rhenium and 0.1 - 15 % of at least one halogen and in that each catalyst of the other beds, contains a carrier of alumina base and, by weight with respect to the carrier, 0.05 - 0.6 % of platinum. 0.05 - 3 % of at least one metal promoter selected from the group consisting of tin, thallium and indium and 0.1 - 15 % of at least one halogen, the proportion by weight of the catalyst containing platinum and rhenium ranging from 8 to 40 % with respect to the total catalyst mass used in all the catalyst beds.

2. - A process according to claim 1, wherein the catalyst of the first catalyst bed wherethrough passes the charge contains, in proportion by weight to the alumina carrier, 0.1 - 0.5 % of platinum and 0.07 - 2 % of . rhenium.

3. - A process according to any of claims 1 to 2 , wherein the catalyst other than that of the first catalyst bed contains, in proportion by weight to the charge, 0.1 - 0.5 % of platinum and 0.07 - 2 % of at least one metal promoter.

4. - A process according to any of claims 1 to 3, wherein the proportion by weight of the catalyst of the first catalyst bed ranges from 10 to 20 % of the total catalyst mass.

5. - A process according to any of claims 1 to 4, wherein the catalyst containing platinum and at least one metal promoter, further contains 0.005 - 0.3 % of iridium.

6. - A process according to any of claims 1 to 5, wherein said metal promoter is tin.

7. - A process according to any of claims 1 to 5, wherein said metal promoter is indium.

8. - A process according to any of claims 1 to 5, wherein said metal promoter is thallium.

9. - A process according to any of claims 1 to 8, wherein at least 2 catalyst beds contain platinum, a metal called promoter and optionally iridium, the catalysts of said two beds being different from each other either by their concentration of metals or of halogen, or by the nature of the metal promoter, or by the optional presence of iridium, or by several of these above-mentioned features.

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