DE1014689B - Process for Making an Improved Hydroforming Catalyst - Google Patents

Description

GERMAN

The invention relates to the production of catalysts for the hydroforming of petroleum spirit are useful, especially those which, with regard to their effectiveness in accelerating hydroforming reactions, their heat resistance in continuous operation and during regeneration as well have improved properties in some other respects.

For hydroforming, catalysts made from platinum or molybdenum oxide on activated are generally used Alumina as a carrier. In the chemical literature, however, there are also suggestions as to what noble metals are to be used as a hydrogenation-dehydrogenation component of hydroforming catalysts and oxides and sulfides of metals of the V., VI. and VIII. Group of the Periodic Table as a carrier.

The hydroforming catalysts according to the invention have the more active form in which they are at high Temperatures are present. Experiments have shown that hydroforming catalysts can be used at calcining temperatures have a greater effectiveness than the same catalysts, which slowly rise to room temperature were cooled. According to the invention, therefore, the cooled catalyst is suddenly quenched to its to maintain a more active state.

The usual process for the preparation of a catalyst which contains, for example, 10 percent by weight molybdenum to 90 percent by weight of alumina, consists in first preparing a suitable carrier, for example an active form of the alumina. An excellent carrier for the dehydrogenation component of a hydroforming catalyst is the η form of the alumina. This form of alumina is obtained by reacting metallic aluminum in the presence of a small amount of mercury chloride or oxide with an alcohol, for example amyl alcohol. The alcohol reacts with the aluminum when heated slightly, for example to about 37 to 50 °, which sets the reaction in motion. Thereafter, the reaction continues smoothly without any further supply of heat. The alcoholate obtained is then hydrolyzed by adding water containing 10 percent by volume of concentrated ammonia. This ammonia-containing hydrolysis water is added slowly to the aluminum alcoholate while stirring. The best results are achieved when the hydrolysis temperature is around 26 to 37 °. The alumina sludge formed during the hydrolysis is left to stand for 4 to 20 hours at approximately room temperature, during which / S-alumina trihydrate is formed. After standing and aging the upper liquid layer from the deposited trihydrate and dries the latter for several hours is separated at 90 to 200 °, wherein the W contained in the alumina ⁷ ater and ammonia are virtually all expelled. The clay that

to produce an improved
Hydroforming catalyst

Applicant:

Esso Research and Engineering Company, Elizabeth, N.J. (V.St.A.)

Representative: Dr. W. Beil, lawyer,
Frankfurt / M.-Höchst, Antoniterstr. 36

Claimed priority:
V. St. v. America 10 August 1954

is almost 100% in the / S-trihydrate form at higher temperatures, e.g. about 590 to 815 °, annealed, then cooled and finally with an aqueous solution a salt or other compound of the hydrogenation-dehydrogenation component impregnated with the catalyst. For the production of molybdenum oxide on alumina catalysts ammonium molybdate can be used as the impregnation solution, while platinum-on-alumina catalysts are used usually a solution of platinum hydrochloric acid in water for soaking the Used clay. In the manufacture of molybdenum oxide catalysts, the impregnated one is heated Carrier, which converts the molybdate salt to the oxide. For the production of the platinum catalysts the impregnated carrier is heated to about 120 ° for a long time, for example 16 hours, and then for deposition of metallic platinum treated with hydrogen. These are the usual methods of manufacture of molybdenum- or platinum-containing hydroforming catalysts.

It has now been found that catalysts with improved properties are produced thereby It is possible to change the treatment following the annealing in the process just described. As already mentioned, this change consists of

TOS 659/385

according to the fact that the catalyst mixture is quenched after the glow. Immediately after the calcination, which lasts for several hours, for example 2 to 16 hours, and preferably runs in a nitrogen atmosphere at temperatures of 590 to 815 °, the catalyst is quenched by placing it in an environment with sufficient heat removal properties to achieve the desired rapid cooling. One such method is, for example, that the hot, calcined catalyst is mixed with a mass of cooled solid particles, the temperature of which corresponds to that of the melting ice or solid carbon dioxide, the hot, calcined catalyst using a sufficient amount of such cool solids within a few seconds is cooled to at least room temperature. These solids can consist of hydroforming catalysts, metal shot, for example stainless steel granules with a diameter of 300 to 400 μ, mullite powder, or any other suitable solid material in the form of small spheres, pills, granules or powder. The hot, calcined catalyst can also be cooled sufficiently quickly in other ways, for example by placing it on a cold surface, preferably a metal surface, or by quenching it in a liquid, for example cold water. In principle, all known methods can be used for rapid cooling of the hot, annealed catalyst, such as are generally used for quenching hot bodies, whereby the catalyst mixture must of course not be attacked chemically or in any other way.

Without wishing to limit the present invention to any particular theory of its effect, one can assume that the effect of quenching or rapid cooling of the calcined catalyst is that the surface energy of the catalysts is caused by disturbances in the crystal lattice during the annealing , regulated and maintained. These lattice perturbations or electron-poor acceptors are important for the interaction of electrons in hydroforming processes. These disturbances can be determined by the known methods for measuring conductivity or specific resistance, as used by physicists for studying semiconductors.
In these measurements, the conductivity or the

ίο reciprocal value of the specific resistance equal to the product of (n) (e) (u), where η is the number of lattice disturbances or acceptors, e is the electron charge and u is the mobility. Measurements of the specific resistance of molybdenum-on-alumina catalysts, which were carried out in large pilot plants during hydroforming experiments, showed that the values of this resistance are correlated with the catalyst activity.

example

Two comparative tests, which were carried out side by side, are described below to show the improved results achievable according to the invention.

In these experiments, a 10 percent by weight molybdenum oxide to 90 percent by weight alumina was used Catalyst prepared in a known manner and then for 6 hours at 718 ° in a nitrogen atmosphere annealed. A portion of the calcined catalyst was then removed from the annealing furnace onto solid carbonated snow poured while another part was allowed to cool slowly in the oven. Either of the two Catalysts were used for a hydroforming experiment. An analysis of the for the hydroforming experiments used charge and the resulting products for their aromatic content is from the can be found in the following table:

Mass spectrometer analysis
Volume percentage

Loading experiment no. 1

in the oven

slow

cooled down

on carbon dioxide snow
chilled

Experiment No. 2

in the oven

slow

cooled down

Chilled on carbonated snow

Benzene,

Toluene,

C ₈ aromatics

C ₉ aromatics

C ₁₀ aromatics

Naphthalenes

Hydrinds

Total aromatics

0.4 4.7 7.3 2.6 0.1 0.3 0.0

15.4 1.2
8.8
12.8
5.5
0.8
0.1
0.2

29.4

1.1
9.6
13.7
5.8
0.8
0.1
0.3

31.4

1.0 8.6 12.7 5.5 0.8 0.1 0.2

28.9

1.0 9.4 13.9 6.4 1.0 0.2 0.3

32.2

These data show an increase in the aromatics content of the hydroformed product using a quenched one Catalyst, with the increase mainly extending to toluene and xylenes, so on Aromatics, which increase the octane number in fuel mixtures.

The catalyst was also tested to determine whether its effectiveness diminishes during regeneration or not. It was therefore treated ten times in succession with hydrogen at 480 ° and then at 540 ° annealed in air (all treatments under ordinary pressure), showing that it has its activity had preserved. This is illustrated by the following data:

Freshly annealed catalyst, with
Cooled carbonated snow ..

The same catalyst after treatment with H _{2 ten times}
and air

Refractive index of the hydroformed in contact with the catalyst Product

1.4303

1.4319

But this is what is obtained after treating the catalyst with H ₂ and air in contact with it

Product about the same as that obtained with a fresh catalyst.

The above-described improvement in the catalysts is of course not only applicable to those containing molybdenum Catalysts, but also found in those containing metals of the platinum group.

The present improvements relate to methods of quenching hydroforming catalysts, after they have been activated by glow. After glowing, the catalyst must be d. H. cooled to about room temperature within 15 to 50 seconds, or at least as quickly as possible will.

Even if in the foregoing now the treatment of a carrier or prepared by the alcoholate process «Thinner ϊ is described in detail it should be noted that other forms of clay can of course be used as a carrier for the hydrogenation-dehydrogenation component can be used by hydroforming catalysts. Good clay suitable as a carrier is not crystalline in form, which instead has a gel structure. To improve the annealing resistance, the alumina carrier should still a small percentage of silica, d. H. 1 to 6 percent by weight (based on the total weight of the Catalyst).

It should also be noted that the molybdenum oxide or the platinum or another active component of the Catalyst, namely the hydrogenation-dehydrogenation component, the carrier both before and after the calcination can be incorporated. Another convenient method of making such a catalyst is that Dry mixing process in which the molybdenum oxide is mechanically mixed with the alumina.

For the preparation of a platinum-on-alumina catalyst prepared by first preferably a mixture of 90% alumina and 10 ° / ₀ and platinum mixed into this as much alumina that the final overall mixture contains 0.5 to 1.5 weight percent platinum, based on the total weight of the catalyst.

Claims (5)

Patent claims: 1. A method for producing an improved hydroforming catalyst, characterized in that that one prepares an adsorptive form of the clay, this clay for 2 to 16 hours Glowing 590 to 815 ° and then quenching the clay. 2. The method according to claim 1, characterized in that one of the alumina before annealing Hydrogenation-dehydrogenation component incorporated. 3. The method according to claim 1, characterized in that the calcined alumina is quenched and only then impregnated with a hydrogenation-dehydrogenation component. 4. The method according to claim 1, characterized in that the hydrogenation-dehydrogenation component Is molybdenum oxide. 5. The method according to claim 1, characterized in that the hydrogenation-dehydrogenation component is a platinum or palladium metal. © 70S '659/385 8.57