DD161192A3 - METHOD FOR PRODUCING BALLENFUL CATALYSTS FOR HYDROCARBON-REFORMING - Google Patents

Abstract

The invention relates to a process for the preparation of spherical catalysts for hydrocarbon reformation. The catalysts consist essentially of alumina and contain as activating components platinum or platinum and rhenium and halogen and optionally other components. The formation of the highly porous and mechanically strong moldings is achieved by a sol-gel conversion, wherein the required degree of dispersion is achieved by a two-stage peptization of the Aluminiumoxidhydrogele. The resulting hydrosol may be further processed in combination with other hydrosols, alumina hydrogels and / or alumina. The active components are uniformly applied to the calcined alumina moldings in an impregnation step. The catalysts produced have in addition to a high porosity and activity also very good strength values.

Description

-2- 215 539

The catalysts contain metals of VIII. Subgroup of the Periodic Table, preferably platinum, or the VIII, and VII. Subgroup, preferably platinum and rhenium in amounts of 0.01 to 1.5Ma .-% and halogen, preferably chlorine, in amounts from 0.2 to 3% by mass. Optionally, the catalysts may contain other metals and / or their compounds from IV. Main group and / or II. Subgroup and / or Vl. Subgroup in amounts of 0.01 to 3Ma .-% based on

contain the respective metal.

The process according to the invention places no special demands on the aluminum oxide hydrogege used, which are preferably of boehmitic nature. By means of the two-stage peptization according to the invention, hydrosols having a high dispersity are obtained which, as a result of strong crosslinking, give mechanically extraordinarily stable catalyst moldings which, when used industrially, lead to minimal abrasion values.

Hydrosol II may be used in admixture with other materials such as hydrosoluble, hydrogel of boehmitic nature, aluminum trihydroxides and / or finely ground aluminum oxides without adverse effect on the mechanical properties for catalyst preparation due to the high degree of cross-linking. This results in the ability to vary both the bulk density and the porosity within wide limits and adjust for the required catalyst properties. Thus, a high pore volume fraction in the macroporous area affects both the absorption of the active components and on

their kataiytische effectiveness very beneficial.

For the peptization of the hydrogels, acids such as nitric acid, hydrohalic acids or carboxylic acids are preferred.

As a coagulation center) is usually ammonia water, the gelled particles within a short time to a

solidified.

For applying the active components advantageously water-soluble compounds of the elements are used, which are preferably impregnated from a common solution. The amount of the solution may correspond to the capacity of the alumina moldings, but preferably it becomes at least twice the amount of solution

applied.

The catalysts prepared according to the invention are distinguished by outstanding properties in the conversion of hydrocarbons to produce high-octane carburetor fuels.

Allsführungsbeispiele example 1

A solution of aluminum nitrate (100g Al ₂ O ₃ / !; 25g free HNO ₃ / I) was Mitteis ammonia water precipitated at a pH of 8.8 and a temperature of 343K to an alumina hydrogel. The suspension was filtered on a filter press and the filter cake was washed with distilled water. The filter cake obtained contained 23.5% by weight of Al ₂ O ₃ . 10kg of the wet cake were placed in a mixing tank with the addition of 0.1851 nitric acid (50%) at room temperature in the hydrosol! transferred. The molar ratio HNO ₃ to Ai ₂ O ₃ is 0.1.

A portion of the produced hydrosol i was heated with stirring for 5 h at 375 K and then cooled to room temperature. The recovered product represents the Hydrosol II.

3 kg of the hydrosol I and 2 kg of the hydrosol II were intimately mixed and dripped through nozzle-like outflow openings at the bottom of a cylindrical container in ammonia water, which was covered with mineral oil. The spherical particles formed were dried after removal of ammonia water at about 380K and calcined at about 800K. The calcined briquettes were soaked with an aqueous solution containing hexachloroplatinic acid, perrhenic acid and hydrochloric acid for 5 hours, with the briquettes constantly covered by the solution. The excess solution was removed after this time and the impregnated moldings dried at about 380K. After 3 hours calcination at 770K, the catalysts had the following composition: 0.35% platinum, 0.35% rhenium, 1.1% chlorine.

Example 2

The catalyst prepared according to Example 1 (Kat.A) was compared in a small-scale pressure apparatus with regard to its performance for the reforming of a hydrocarbon fraction with a catalyst prepared according to a conventional Strgngverformungstechnologie catalyst of the same composition (Cat. B): Test conditions: pressure

temperature

burden

catalyst makes

Raw material: hydro-refined straight run gasoline of boiling range 378 to 413 K Result: aromatic content

in reformat Vol .-%

Octane RON

Liquid yield Ma .-%

The test results show the advantageous properties of the catalyst according to the invention for the reforming.

MPa 1.0 K 778 1/1 h 2.0 cm ³ 100 it's 378 to 413K Cat.A Cat. 72 70 99.8 98.3 85.1 85.8

Claims (3)

1. A process for the preparation of spherical catalysts for hydrocarbon reforming, consisting essentially of alumina and containing as activating components platinum or platinum and rhenium and halogen and optionally further components, by coagulation of alumina hydrosols or alumina hydrosols containing mixtures, characterized in that the Peptisation of Akifniniumoxidhydrogelen carried out in two stages, wherein in the first stage a predominantly boehmite-containing hydrogel with etner basic salts forming acid in the molar ratio of acid / hydrogel from 0.05 to 0.20 at room temperature fn a hydrosol I low dispersity and viscosity with a water content in Limits vn 60-90% converts, in the second stage, the hydrosol I by treatment at 323 to 423K, preferably at 353 to 403K within 0.1 to 24 hours in a hydrosol II converted with the desired degree of dispersion, the hydrosol Il obtained if appropriate in combination with hydrosol I, alumina hydrogels and / or aluminum oxides in amounts of 1 to 80% at solids concentrations of 150 to 400 g / l by means of a coagulation medium to form spherical particles, these thermally post-treated in a conventional manner at temperatures up to 923K, the activating components applied evenly to the moldings by a simultaneous or consecutive impregnation step and the catalysts thus prepared are dried at temperatures up to 473K and optionally calcined at temperatures up to 850K in oxygen-containing atmosphere. -1- 215 539 Invention claims: 2. The method according to item 1, characterized in that the catalysts are metals of VIII. Subgroup of the Periodic Table, preferably platinum, or VIII, and VII. Subgroup, preferably platinum and rhenium, in amounts of 0.01 to 1.5Ma .-% and halogen, preferably chlorine, in amounts of 0.2 to 3Ma .-% and optionally further metals and / or their compounds from the IV. Main group and / or II. Subgroup and / or Vl. Subgroup in amounts of 0.01 to 3 wt .-%, based on the metal. Field of application of the invention The invention relates to a process for the preparation of spherical catalysts for hydrocarbon reforming, which consist essentially of alumina and as activating components platinum or Pjatin and rhenium and halogen and optionally contain other components, wherein the formation of highly porous and mechanically strong moldings by a sol-gel Conversion is achieved. Characteristic of the known technical solutions For the reforming of hydrocarbon fractions of the gasoline boiling range, catalysts are used which contain small amounts of platinum on porous alumina. By various additives to the hydrogenation-active platinum, in particular of rhenium, iridium, germanium, tin, lead, titanium, cadmium u.a. the catalyst properties could be significantly improved. In addition to the use of catalysts in the form of strands (eg DE-OS 2013511, WP C 10g / 199537) and hollow strands (DD-PS 121255), the use of spherical catalysts is also known (DD-PS 30930, US-PS 3950243, DE-OS OS 2222550). Regardless of the shape of the catalyst particles, a variety of possible active component combinations will be described. The most common methods of preparing spherical reforming catalysts are characterized by particular effects of the nature and conditions of preparation of the starting products on the utility properties of the catalysts produced. Thus, for example, alumina hydrogels, which are obtained by precipitation or hydrolysis reactions and are in dried form, can be processed by the known processes only to an insufficient degree or with increased technological complexity to give spherical particles having the required quality characteristics. Thus, apart from insufficient strength values, the requirements for the porosity values are met only to an unsatisfactory extent. To solve these problems, only insufficient measures, such as a partial mixing of the hydrosols with basic compounds (US-PS 3 "943071) and ^ additional aging steps (US-PS 3642660, US-PS 3943071) are described. Object of the invention The aim of the invention is to provide a technically applicable and compared to the known technologically simple process for the preparation of spherical reforming catalysts in which from relatively well crystallized hydrogel precipitates using a sol-gel conversion alumina molded body of the desired dimensions are produced, in addition to high mechanical Strengths also have very good and variable porosity and after application of the required active components ensure their effectiveness to a great extent. Explanation of the essence of the invention The object of the invention was thus to design the necessary for the preparation of the catalyst moldings peptization of Aluminiumoxidhydrogele so that are obtained by setting a required degree of dispersion Aluminiumoxidhydrosole, resulting in their further processing mechanically strong and highly porous moldings active after application of the required active components and give stable catalysts for the hydrocarbon conversion. According to the invention, the object is achieved by a process for preparing spherical catalysts for hydrocarbon reformation, which consist essentially of alumina, by coagulation of alumina hydrosols or mixtures containing alumina hydroxides, wherein the peptization of alumina hydrogels is carried out in two stages and in the first stage a predominantly boehmite-containing hydrogel with an acid / hydrogel molar ratio from 0.05 to 0.20 at room temperature into a low dispersity hydrosol I and viscosity with a water content between 60 and 90%. In the second stage, the hydrosol I is converted by treatment at 323 to 423K, preferably at 353 to 403K within 0.1 to 24 hours in a Hydrosoi II with the desired degree of dispersion. The resulting hydrosol II is optionally, in combination with hydrosol I, alumina hydrogels and / or alumina in amounts of 1 to 80% at solids concentrations of 150 to 400g / l formed by means of a coagulating to spherical particles, which in a conventional manner at temperatures up to 923Kertherftertreated become. In a subsequent simultaneous or consecutive Imprägtjierungsschritt the activating components are uniformly applied to the moldings, dried at temperatures up to 473 K and optionally calcined at temperatures up to 850 K in an oxygen-containing atmosphere.