DD250061A1 - METHOD FOR PRODUCING A CATALYST FOR HYDROISOMERIZATION - Google Patents

Abstract

The aim of the invention is a preparation process for a catalyst, which is characterized by both high selectivity and high conversion rate of ethylbenzene to xylenes. The object to develop a process for the preparation of a catalyst for hydroisomerization, which is characterized by a technologically simple procedure is solved by according to the invention as a zeolite component by verduennte mineral acid to a Na2O content of 1.5 to 2.5 Ma .-% brought mordenite, as a second zeolite component mixed by digested mineral acid to a Na2O content of 0.2 to 1.0 Ma .-% mordenite, as a third component pseudoboehmite and as a fourth component bayerite as a fine powder mixed together and this mixture in further processed in a known manner. The invention is used for the hydroisomerization of ethylbenzene-containing C8 aromatic fractions.

Description

The total content of mordenite is about 15 to 50 mass%. The mass ratio of mordenite with higher Na ₂ O content (1.5 to 2.5 Ma .-%) to mordenite with lower Na ₂ O content (0.2 to 1.0 Ma .-%) is within the limits of about 2: 1 to 1: 2. Synthetic mordenite with a modulus (SiO ₂ : Al ₂ O ₃ : molar ratio) of about 10 is used. The synthetic mordenite with an initial Na ₂ O content of about 8.5% by mass is mixed with dilute mineral acid, e.g. B. 4 m HNO ₃ , in the mass ratio 1: 2 to 1: 6 treated at ambient temperature for a few hours, so that the Na ₂ O content after separation from the solution and washing with clean water between 1.5 and 2.5 Ma .-% lies. The second mordenite component having the lower Na ₂ O content is preferably prepared by repetitive acid treatment of the acid-treated mordenite described above, and similar ratios can be used. As the clay component, pseudoboehmite and bayerite are used as finely divided powders in the ratio of about 1: 3 to 1: 5.

The moldings are best soaked with a solution of H ₂ PtCl, to which chloride ions in the form of hydrochloric acid are added in addition, so that the Cl content of the finished catalyst is 0.8 to 2.5 wt .-%. The platinum content is about 0.15 to 0.5 mass%. After impregnation, the catalyst is heated at 450 to 600 ⁰ C in an air stream, so that the ignition residue at 1000 ⁰ C is at least 95 mass%.

Surprisingly, the combination of the mordenite products with different Na ₂ O content for the catalyst gives the desired high selectivity and ethylbenzene conversion to xylenes activity.

embodiments

The following catalysts were prepared: Catalyst A

To prepare Catalyst A, 2.55 kg of bayerite, 2.08 kg of boehmite and 1.7 kg of an acid-treated mordenite in powder form were thoroughly mixed, and 1.25 kg of pseudoboehmite hydrogel as a wet filter cake, 11% Wasse.r and 0.8110% solution of ethoxycellulose added and mixed the mixture in a vortex mixer, so that a plasticized mass was formed. This mass was pressed by means of a screw extruder through nozzle plates with a vortex profile, and thereby formed moldings with a circumscribing diameter of 1.5 mm with vortex profile, which were then dried and annealed at 500 ⁰ C. The annealed moldings were impregnated with a solution of H ₂ PtCl ₆ , which additionally contained 2% by weight of HCl and 3% by weight of acetic acid, in each case based on the molding charge, with a platinum content of 0.4 .mu.m. -%, based on the blanks, was offered.

The mordenite used had a residual Na ₂ O content of 1.8Ma .-% after treatment with 4m nitric acid in the ratio of 4: 1 (amount of nitric acid: Mordenitmenge) at room temperature with stirring. Treatment time 5 hours. As the starting mordenite, a synthetic product having a modulus (SiO ₂ -Al ₂ O ₃ molar ratio) of 10.2 and a Na ₂ O content of 8.5 mass% was used. After drying the impregnated moldings at 12O ⁰ C, the following chemical composition was obtained:

Mordenite 30Ma .-%

Platinum 0.39% by weight, based on the residue on ignition at 800 ^° C.

Chlorine 1.2Ma .-%

Residual residue 91.5Ma .-%

at 800 ^° C

Catalyst B

The catalyst was prepared as the previously described catalyst A. The mordenite component used was an acid-treated product having a residual Na ₂ O content of 1.2% by mass, which was produced by treating the synthetic mordenite with 4m nitric acid in a ratio of 5: 1 (nitric acid to mordenite) at room temperature with stirring. Treatment time 5 hours.

Analysis as for Catalyst A

Catalyst C

The catalyst was prepared as the previously described catalyst A. The mordenite component was a double treatment with 4m HNO ₃ in the ratio 4: 1 (amount of nitric acid: Mordenitmenge) at room temperature with stirring. Treatment time 5 hours each. The Na ₂ O content of the mordenite was 0.5% by mass.

Analysis as for Catalyst A

Catalyst D

The catalyst was prepared as catalyst A. As Mordenitkomponente a mixture of 570 g of the mordenite used in catalyst A having an Na ₂ 0-served Gehaltvon 1.8mA .-%, and 1130g of the mordenite with an Na ₂ O used for Catalyst C-content of 0.5 wt .-%.

Analysis as for Catalyst A

Catalyst E

The catalyst again became Catalyst A with the same mordenite component having a Na ₂ O content of 1.8 mass%. Instead of the use of acetic acid in the impregnation only hydrochloric acid in an amount of 2 wt .-%, based on the molding insert amount offered. Subsequently, the moldings were dried and annealed at 500 ⁰ C in a stream of air.

Analysis: Mordenite 30Ma .-%

Platinum 0.39% by weight, based on the residue on ignition at 800 ^° C.

Chlorine 1.2Ma .-%

Residual residue 97Ma .-%

at 800 ° C

Catalyst F Preparation as Catalyst A with the mordenite component of Catalyst B (1.2Ma% Na ₂ O). Impregnation of the moldings as in Catalyst E.

Analysis as for Catalyst E

Catalyst G Preparation as catalyst A with the mordenite component of Catalyst C (0.5Ma% Na ₂ O). Impregnation of the moldings as in Catalyst E.

Catalyst H (according to the invention) Preparation as catalyst A with the mordenite components of catalyst D (0.5 or 1.8% by mass Na ₂ O in the ratio 1: 2).

Impregnation of the moldings as in Catalyst E.

Analysis as in Catalyst E Catalysts A to H were used in a small-scale experiment for the hydroisomerization of an ethylbenzene-containing Ce aromatic mixture.

Conditions:

- H ₂ pressure in MPa 1.25 temperature in ⁰ C

- load in v / vh 3.0

- H ₂ : hydrocarbon ratio 5: 1 mol / mol

- Runtime in hours

In the table, the raw material composition and the Isomerisatzusammensetzungen on the catalysts A to H are compiled. Furthermore, Ethylbenzenapproach, p-Xylenapproach (approximations to the thermodynamic equilibria) and the xylene formation and the C ₈ aromatics losses are listed.

It turns out for the inventive catalyst H, a surprisingly high conversion of ethylbenzene to xylenes, as it is not observed to the extent in the comparative catalysts.

table

Raw material composition and composition of the isomerizates when using the C ₈ -Aromatengemisches on the catalysts A to H

catalysts

Hydrocarbons raw ABCDE FGH

in% by weight

nonaroms. 1.5 4.9 7.5 7.0 '8.5 7.5 5.3 6.2 6.3 benzene O 0.9 1.1 1.0 2.2 1.5 1.2 1.5 1.5 toluene 2.5 3.3 2.3 2.5 3.0 2.6 4.0 3.0 4.5 ethylbenzene 23.5 16.8 16.4 15.6 10.8 14.7 14.1 15.1 9.5 p-Xylene 8.8 16.6 16.1 16.7 17.0 16.7 * 17.4 17.0 17.9 m-xylene 46.7 39.8 38.1 38.2 39.7 38.1 38.6 38.4 39.7 o-xylene 17.0 17.6 16.2 16.8 16.2 - 16.5 17.5 16.7 17.6 Gg ⁺ -ArO mate η 0 0 2.3 2.2 2.6 2.4 2.2 2.1 3.0 Ethylbenzenapproach - 40.0 37.3 44.2 77.3 54.0 55.7 47.9 88.6 p-xylene approx. in% 86.8 84.0, 92.6 92.6 95.3 100.0 96.8 98.7 Xyiengewinn in Ma .-% - 1.5 -2.1 -0.8 0.4 - 0.2 0.7 -0.4 2.7 Cs-Aromatenverluste - 5.2 9.2 8.7 12.3 10.0 8.7. 8.8 11.3 in% by weight

Claims (1)

A process for the preparation of a catalyst for the hydroisomerization of ethylbenzene-containing C ₈ aromatics fractions containing an acid-treated mordenite-type zeolite, alumina and platinum and chlorine, and blending the individual components of synthetic acid-treated mordenite whose potential replacement positions are occupied by about 2 to 30% sodium cations and alumina hydrate, shaping, annealing and impregnation with a platinum compound containing chloride ions and thermal aftertreatment, characterized in that, as a zeolite component, a dilute mineral acid is added to a Na ₂ O content of from 1.5 to 2.5Ma. % yielded mordenite, as a second zeolite component mixed by diluted mineral acid, preferably in two stages, to a Na ₂ O content of 0.2 to 1.0Ma .-% mordenite, as a third component pseudoboehmite and as a fourth component bayerite as a fine powder mixed together, the mixture in an sic h forms a known manner to particles, this glows and soaks the resulting particles with a solution containing chloride ions, dries and glows. Field of application of the invention The invention relates to a process for the preparation of a catalyst for the hydroisomerization of ethylbenzene-containing C ₈ aromatic fractions. Characteristic of the known technical solutions Known is the preparation of a catalyst for the conversion of hydrocarbons, including the isomerization of alkene aromatics, in which a finely divided mordenite dispersed in a Aluminiumoxidsol, the resulting mixture is formed into particles, dried and calcined and the calcined particles with a noble metal, for. As platinum, and preferably a halogen, for example as chloride ions, are combined (DE-AS 1545418). The mordenite can be converted, for example, by exchange with ammonium ions and subsequent calcination prior to dispersion in the Η-form or extracted with mineral acid, wherein a portion of the lattice aluminum is dissolved out of the crystalline zeolite (DE-AS 1 920546, Sp , DD 103885). The Na ₂ O content of the mordenite in the proposed catalysts is, for example, 0.25 and 0.55 mass%, respectively. However, this procedure is technologically very complicated. A catalyst having improved selectivity for the conversion of ethylbenzene to xylenes arises when the alkali ion content of the mordenite after the acid treatment is brought to values between 20 and 60 equivalent% of the remaining potential cation positions (DD 121320). Preferably, the acid-treated mordenite is recatized with sodium ions to select the catalyst. The disadvantage, however, is that although a good selectivity of the catalyst is achieved by the high Na2O content of the mordenite, but the conversion rate of Ethylbenzene is still insufficient. This disadvantage could not be eliminated by later proposals to improve the catalyst (DD 138007, DD 140207, DD 150382, DE 2823567, DD 218738). Object of the invention The aim of the invention is to propose a process for the preparation of a Pt-Al ₂ O ₃ mordenite catalyst for the hydroisomerization of ethylbenzene-containing C _s aromatic mixtures, which is distinguished by both high selectivity and high conversion rate of Ethylbenzene to xylenes. Explanation of the essence of the invention It is the technical object to develop a process for the preparation of a catalyst for hydroisomerization, which is characterized by a technologically simple procedure. This object is achieved by a process for preparing a catalyst containing an acid-treated mordenite-type zeolite, alumina and platinum and chlorine, and blending the individual components of synthetic acid-treated mordenite whose potential replacement positions are about 2 to 30% with sodium cations and alumina Hydrate, shaping, annealing and impregnation with a chloride ion-containing platinum compound and thermal aftertreatment is prepared, solved by bringing in accordance with the invention as a zeolite component by dilute mineral acid to a Na ₂ O content of 1.5 to 2.5Ma .-% Mordenit and as a second zeolite component by dilute mineral acid, preferably in two stages, to a Na ₂ O content of 0.2 to 1.0Ma .-% brought Mordenite, as a third component pseudoboehmite and as a fourth component bayerite as a fine powder mixed together, the mixture in in a manner known per se to particles f ormt, this glows and the resulting particles with a solution containing chloride ions soaks, dries and glows.