DE2049809B2 - Dehydrogenation catalyst - Google Patents

Description

The present invention relates to one containing nickel, chromium, aluminum, copper and alkali Dehydrogenation catalyst with improved properties and a process for its preparation and its use in the manufacture of hydroxydiphenyl.

According to German patent specification 1 108 221, 2-HydroxydipheDyl can be obtained by dehydrogenation of cyclohexylidenecyclohexanone on a carbon dioxide-treated nickel catalyst deposited on chromium and / or aluminum oxide, dei still contains additives of alkali oxides, copper or silver.

³ 4

& ² ^ fS ^ **. ' ^{that 4} Hf ^{effectiveness of} a satois with metallic nickel from about 10 to

***** ^ r ^ Ä * ^ if ^{!? * k} ^ ^{r Reakti} ° as- 35 weight percent can be further reduced,
^ ner subsides. In addition to 2-hydroxydiphenyl is formed

^ Increasingly 2 ^ clohexylphenoL what the Although alkali sulfate-containing nickel

iBdunschen use of the catalyst by way of 5 chromium-copper catalysts for other dehydration

_tv , teht, especially since its activity by burning off with ventilation methods, z. B. for the production of phenol

Vwid considerable reduction only for a short time again from cyclohexanone and cyclohexanol, produced

Can be raised (U.S. Patents 2,588,359 and 2,640,084

EiO waterer Nachted des in the patent specification and Ind. Engng. Chem., 44, 1696 [1952]), but from

An additional dehydrogenation process consists in the fact that these catalysts are already in use

, one kisses to suppress dehydration- their gross composition and structure of the

processes that lead to the formation of diphenyl, differ for example catalysts described above, is

Mol percent water has to be added, which is partly known from catalytic practice that

hydrolytic splitting of the Cvdohexyüdencyclo- the transfer of very special conditions of a

Resulting from hexanone has ₁₅ procedure on another procedure not without

To avoid this for the hydroxydiphenyl further is possible. This is shown in this case

There are two types of production after the catalytic process: Phenol catalysts of the type mentioned

Dehydration of compounds and / or compounds are völhg for the production of hydroxydiphenyl

dgemiscnen made entirely and / or partially unsuitable (see Example 5). Alkaline salt additives to other

hydrogenated hydroxydiphenyl, refers to ao ren nickel-chromium-copper or nickel-chromium-aluminum

the present invention therefore to effect a nickel, minium-copper catalysts on their own

Chromium, aluminum, copper and alkali in quantities - no significant improvement in their effectiveness

Ratio of the metaUs from 40 to 60: 6.8 to 17.1: 1.6 k wise (see. Catalysts A and C in Example 1

up to 8.0: 0.05 to 1.0: 0.65 to 3.4 containing De- and 2).

hydrogenation catalyst, produced by relocating as The present invention further relates to a verder obtained by fusing, nickel, chromium, aluminum for producing a base material containing nickel, chromium, aluminum and copper with dehydrogenation of an alkali metal compound containing nium, copper and alkali, followed by a dry catalyst with a quantitative ratio of the metals voltage and deformation, reduction at increased temperature, nickel to chromium to aluminum to copper to alkali temperature with hydrogen and optionally then 40 to 60: 6.8 to 17.1: 1.6 to 8, 0: ßende treatment with CO ₁ in the heat, and is there- 0.05 to 1.0: 0.65 to 3.4, where the obtained by precipitation is characterized by that obtained, nickel, chromium, aluminum and copper

containing base mass with an alkali metal compound

a) the base mass is mixed with alkali metal sulfate and / or alkali bond, then dried and carbonate is formed as alkali compound in the appropriate form, is impregnated with hydrogen reducing amount at elevated temperature, decorated and, if necessary, then in the heat with CO ₁

b) the impregnated and dried catalyst is treated, characterized in that the mass to bodies with a bulk weight of measures a) to d) above. 0.8 to 1.6 g / ml, in particular 0.9 to 1.4 g / ml, molded to produce the catalyst according to the invention will, 40 goal? one assumes a nickel, chromium, aluminum

c) the resulting catalyst moldings in the case of Tempe- and copper-containing catalyst base, ratures between 350 and 420 ° C initially with the one according to known methods, for. B. by geetwa the half to double that for the reduction joint failures from a nickel, chromium, tion of the nickel compounds to aqueous containing metallic aluminum and copper nitrate Nickel and optionally the chromium (VI) -ver- 45 solution by means of sodium hydroxide solution, e.g. B. according to the bonds to compounds of the trivalent German patent 889 591 can be obtained. the Chromium's calculated equivalent hydrogen-chromium compound can be used, for. Bi. Also in six quantities reduced-valued form within 1 to 4 hours (see e.g. Catalysis Handbook, be, and Vol. VII, 1. Half te, p. 674, or Houben-Weyl,

d) either at the earliest one week after the 50 vol. 4/2, p. 179) use and instead of step c) the catalyst moldings with caustic soda z. B. also use ammonia, alkali carbonates 2 to 10 times that for the reduction of or alkali hydrogen carbonates (see H ο u-nickel compounds of the catalyst to metalü- ben —Weyl, Vol. 4/2, p. 137ff .; manual of the schem Nickel calculated equivalent water catalysis, Vol. V, Het. Cat. II, p. 41.2 ff.). Depending on the amount of substance within 1 to 4 hours at the precipitation conditions, ie depending on the temperatures used between 350 and 420 ° C up to the precipitant, pH of the solution and the type of metallic chromium compound used in the catalyst, the nickel falls nickel from about 10 to 35 weight percent e.g. B. as a hydroxide, as a basic carbonate (see e.g. further reduced or the catalyst form- G me 1 in, 8th edition, Part B, Lief. 3, Syst. No. 57 linge immunized after process stage c), 60 [1966], pp. 846 to 853) or from ammonium mills and again to form shapes with a nickel chromate (see Gm el in, 8th edition, part B, bulk density of 0.8 to 1.6 g / ml. Lief. 3, Syst. No. 57, pp. 1215 and 1216). A mögden and then with about 2 to 10 times the loan variant for the preparation of the catalyst base for the reduction of the nickel compounds mass consists, for. B. also in the fact that a carbonate-hydroxide mixture from 1 to 4 hours at temperatures between falls from one of the catalyst to metallic nickel and this after washing out with ammonium 350 and 420 ⁰ C up to a content of the catalysis bichromate is reacted at an elevated temperature.

This catalyst base material will, more appropriately, mix the completely and / or partially hydrogenated

wise before the deformation, according to the invention, such hydroxydiphenyl exist.

impregnated with alkali sulphate or alkali carbonate so that suitable starting materials for the

the proportions of the alkali metals to the proper use of the catalyst for production

Metals nickel, chromium, aluminum and copper, 5 of hydroxydiphenyl are for example: 0.65 to 3.4, preferably 0.95 to 2.8 to 40 to 60 too

6.8 bu 17.1 to 1.6 to 8.0 to 0.05 to 1.0. 2-cyclohexylidenecyclohexanone,

In addition to the gross composition of the catalysis 2-cyclohexenylcyclohexanone, gates are a way of deforming a catalyst

and reduction of equally decisive influence 10 2-C / clohexylcyclohexanone,

on the selectivity and lifetime of the catalyst. 2-cyclohexylcyclohexanol,

The deformation of the catalytic converter is more practical- »rw.ir« i «.Tvin» ii> .nr «l

wise Anf tablet presses according to the invention so by- 2-uycionexyipnenoi,

led that the bulk density of the catalyst 3-cyclohexylphenol,

tablets between 0.8 and 1.6 g / ml, especially 15 4-cyclohexylphenol, between 0.9 and 1.4 g / ml. The tableting

can be done one or more times. For tablet sizes 2-phenylcyclohexanone,

2-Phenylcyclohexanol is obtained with a diameter of up to e * wa 3 mm. especially in general with simple tableting;

For larger tablets, double tableting of 20 is possible. These are passed individually or in a mixture with

recommend. each other in vapor form at temperatures of about

The reduction of the catalyst should take place from 300 to about 400 ^° C., in particular from about 320 to

that the content of metallic nickel in the finished about 350 ° C, under normal pressure or reduced

Catalyst between about 10 and about 35 weight pressure across the catalyst. Percent lies. a ₅ One obtains in this way with space velocity over the catalyst of about

According to the invention, the reduction was carried out in two stages from 0.2 to about 0.4 g of starting product per ml of catalyst. The first stage of the reduction is carried out with a gas generator and an hour at normal pressure, for example. B. from the for about half to double the amount of hydrogen that the 2-hydroxydiphenyl production suitable Ausfür the reduction of nickel compounds to metal transition compounds in addition to about 88 percent by weight of nickel and optionally chromium (VI) - 30 2-hydroxydiphenyl about 3 to 5 percent by weight of the compounds to compounds of the trivalent abovementioned, reusable compounds, chromium is theoretically required and is used within so that the catalyst selectivity is over 90% ⁰ C, preferably at 370 to 390 ⁰ C, preconditions in 1000 hours mostly not more than assumed. 35 3 to 5% with a corresponding increase in recyclable

After the first reduction stage, a valuable share takes place. Under working conditions, at Intermediate treatment which, in two ways, results in the evaporation of the starting product in the

can be performed. Either the cataly- tic upper part of the furnace is made itself, he

after the first reduction stage min

Stored for at least a week, or they will become immune to resinous compounds on the catalyst

sized, ground and formed again with a naturally somewhat faster process.

Deformed bulk density from 0.8 to 1.6 g / ml. After the hydroxydipbenyi share has dropped to 60 to Immunization is done by overheating by 70%, it is expedient to rinse the catalyst Regenerate ammonia and carbon dioxide sequentially or by using a solvent. Suitable

Carried out in diluted air. 45 solvents are e.g. B. xylene, cyclohexanol, phenol,

The second stage of the reduction takes place with about diphenyl ether and dimeric condensation products

2 to 10 times the amount of hydrogen required for the Re- des Cyclohexanons.

After flushing, the catalyst in the stick nickel is theoretically required, and the material flow will also be heated to operating temperature within 1 to 4 hours at temperatures of so and is thus ready for use again, about 350 to 420 ⁰ C, preferably at 370 to 390 ° C. The catalyst to be used according to the invention is carried out. stands out over known catalysts, e.g. B.:

A second immunid from German patent specification 1108 221, through |

lation of the catalyst, e.g. B. with carbon dioxide with the following advantages: I.

100 ⁰ C or z. B. with very dilute air at room 55 The life of the new catalytic converter is around one |

temperature, connect. But it is also sufficient to increase the multiple. The catalyst also works at |

Catalyst adsorbed hydrogen largely due to the absence of water and also after prolonged | To displace nitrogen or carbon dioxide. Operating time very selective in terms of dehydration. I. The catalyst prepared according to the invention is suitable. The dehydrating influence is greatly weakened

particularly suitable for the synthesis of hydroxydiphenyl 60 The new catalyst can be easily regenerated:

by catalytic dehydrogenation of compounds by simply rinsing with a solution _:

and / or mixtures of compounds, which consist of whole or / medium at a slightly elevated temperature, e.g. B. with phenol

and partially hydrogenated hydroxydiphenyl. at 170 ° C.

The subject of the present invention is therefore this considerable improvement in the mode of action

Furthermore, the use of the catalyst described above is due in particular to

Bene way obtained catalyst for the production of the combined influence of the addition of alkali salts on

of hydroxydiphenyl by catalytic dehydration- the type of reduction conditions used and

tion of connections and / or connection to the specific type of catalyst deformation Art

and the extent of this influence were surprising and unforeseeable.

The hydroxydiphenyl produced by the claimed process has already found important areas of application, e.g. B. as a preservative for Citrus spruce or as an accelerator for dyeing with disperse dyes.

In the following examples,% means percent by weight, unless otherwise stated. Parts by weight relate to parts by volume as g to ml.

Examples I. Preparation examples example 1

5 The production of the catalysts A to N took place according to the steps given in Table 1, these steps being carried out sequentially from left to right. The main characteristics of the catalysts are shown in the last three columns of Table 1 ίο stated.

Table 1

Kata
ly
sator Kata-
Iy-
sator
Dimensions
ⁱ m 1st Ta
blettie
tion
Press
pressure 1. Treat
ment with
Hydrogen ⁴ ) Immunization
tion after
1. H ₁ -B-
act ⁹ ) *) Between
treat
lung 2nd Ta
blettie
tion
Press
pressure 2. Treat
ment with
Hydrogen ⁴ ) To
treat
lung ') ·) Done
Bulk
ge
wfcht
(g / ml) srKatal
Ni-G
(5
metal. ysator
"stop
i)
ge
velvet A. 1 strong 2.5 h 100 VT
390 ⁰ C no no - no 3OhCO,
100 ⁰ C 1.36 8.6 49.5 B. 1 strong 2.5 h 100 VT
39O ° C no 3 weeks
I _n ι, -. .-
l8 £ Gfu - 2.5 h 760 VT
39O ⁰ C 3OhCO,
100 ⁰ C 1.30 13.7 51.7 C. 2 strong 2.5 h 100 VT
390 ⁰ C no no - no 3OhCO,
10O ⁰ C 1.31 4.6 47.2 D. 2 strong 2.5 h 100 VT
39O ⁰ C no 3 weeks
to store - 2.5 h 760 VT
39O ⁰ C 3OhCO,
100 ⁰ C 1.28 12.1 49.4 E. 3 small amount 2.5 h 100 VT
380 ⁰ C no no - no 3OhCO,
100 ⁰ C 0.84 12.6 52.4 F. 3 small amount 2.5 h 100 VT
38O ⁰ C no no - 2.5 h 1200 VT
39O ⁰ C no 0.85 26.2 52.7 G 3 moderate 2.5 h 100 VT
39O ⁰ C no no - 2.5h 725VT
390 ⁰ C 30 h CO,
10O ⁰ C 0.90 24.8 52.4 H 3 moderate 2.5 h 100 VT
390 ° C NH ₁ , CO ₁ , rt grind moderate 2.5 h 725 VT
390 ⁰ C 3OhCO,
100 ⁰ C 0.94 27.4 51.2 3 3 moderate 2.5 h 100 VT
39O ⁰ C NH ₁ , CO ₁ , rt grind strong 2.5 h 725 VT
39O ⁰ C 3OhCO,
100 ° C 1.14 22.4 49.5 K 3 moderate 2.5 h 100 VT
390 ° C NH ,, CO ,, RT grind strong 2 ^ h 725 vt
390 ° C 3OhCO,
100 ⁰ C 1.20 26.2 51.6 L. 3 moderate 2.5 h 100 VT
39O ⁰ C 2% air 98%
CO ,, RT grind powerful 2.5 h 725 VT
390 ⁰ C 3OhCO,
100 ⁰ C 1.12 22.0 49.9 M. 3 moderate 2.5 h 100 VT
390 ⁰ C NH ,, CO..RT grind powerful 2.5 h 725 VT
390 ⁰ C 12h2% air,
98% CO * RT 1.12 21.5 50.1 N 3 moderate 2.5 h 100 VT
390 ⁰ C NH ,, CO ₁ , RT grind powerful 2.5 h 725 VT
37O ⁰ C 3OhCO,
100 ° C 1.10 19.2 49.4

manufactured.

The catalysts A, C, E, F and G were to be compared Comments on Table 1

*) The catalyst composition 1 was obtained as follows. In a known manner, a mixed carbonate-hydroxide precipitate was obtained from an aqueous solution containing the elements Ni, Al and Cu in the form of nitrates by precipitation with sodium carbonate solution, which after washing and reaction with ammonium bichromate solution 38.5% Ni, 7, Contained 5% Or, 1.8% Al and 0.4% Ci. 357.5 parts by weight of base composition were mixed catalyst aufgeschlimmt with a solution of 8.1 parts by weight of potassium sulfate in 330 Vo lumen share water, dried at 120 ⁰ C, ground, mixed with 3% graphite and formed on a Exzenterpres »to 2.4 mm pellets

·) The catalyst composition 2 was produced in accordance with the catalyst composition 1, but the base catalyst composition from the slurry with potassium sulfate reading contained 38.2% NL iß% Cr, 3.2% Al and 0.2% Cu. 357.5 parts by weight of this catalyst base material were slurried with a solution of 9.4 parts by weight of potassium sulfate in 330 parts by weight of water, dried, ground and made into 2.4 mm tablets in the usual way

*) The catalyst composition 3 was produced according to the Katah / satonnasse 2, but 12 870 Gewkhtsteöe of Ni, Cr A! and Cu-containing catalyst base with a solution of 337.5 parts by weight of potassium sulfate in 11700 weight share Wassa slurried After drying, Mahhmg nod the addition of 1.5% graphite, 5-mm tablets were produced

*) VT means parts by weight of H, per part by weight of tablets and status.

>) RT means room temperature.

·) In each case volume percent

II. Application examples weight of a mixture of 97 percent by weight '

_. . , - 2-Cydohexenylcycloheranon and 2-Cyclohexylidcn

B e ι s ρ ι e I Z cyclohexanone, 2.5 parts by weight of 2-cyclohexylcydo

Lim tubular reactor with a tube diameter of 65 hexanone and 0.5 parts by weight of cyclohexanone, ibid

of 17 mm, the upper part of which is siert evaporation zone. The catalyst temperature is ^{330 ° C. during this}

is used, is held in the lower part with 30 volume. The results are summarized in Table 2

share catalyst filled. Every hour 6, OCSe are collected

Table 2

10

Operating hours ·) 4100 2-hydroxy
diphenyl Preliminary products ¹ ) 5 Not again
usable
Products Again
usable
Products selectivity catalyst 11 % % 10 % % under
Consideration
again
usable 55 280 81 2.0 7th 11.0 6.0 Products)
% A. 320 57 53 2.4 8th 10.0 28.6 87 A. 70 280 83 0.5 7th 9.5 7.0 75 B. 1500 33 66 0.5 7th 4.5 28.0 90 B. 50 280 81 1.5 8th 12.9 4.6 92 C. 160 80 58 1.9 6th 8.8 31.3 85 C. . 70 800 85 0.5 9 9.0 5.5 85 D. 1450 70 65 1.2 6th 8.0 26.3 90 D. *) 800 72 1.0 8th 6.2 20.8 89 D. 2700 75 60 1.4 7th 6.0 32.6 91 D. "> 800 70 0.8 8th 7.1 22.1 90 D. 3300 75 60 1.0 6th 7.7 31.8 90 D. 800 78 1.4 9 8.2 12.4 89 D. 60 68 1.6 10.2 20.2 90 D. 800 84 7th 11 86 E. 55 35 95 E. 81 12th 85 F. 62 30th 92 F. 82 11 89 G 66 26th 92 G 82 10 90 H 67 27 91 H 84 7th 92 I. 66 28 90 I. 83 9 92 L. 66 27 92 L. 84 8th 91 M. 65 29 92 M. 82 9 92 N 65 28 90 N 91

Comments on Table 2

*) Pre-products are low-boiling compounds, in the average benzene and phenol. *) Compounds that can be used again are essentially diphenyl and 1 *) Re-usable compounds are: 2-Cydohe (ylphcnol, 2-Pbenylcyt

cyclohexanone, 2-QrdohexyMenHtfclohexaiKm, 2-Cydobexyl ^ clohcxaoon .: *) After rinsing the catalyst at 200 ° C for 2 hours with 100 °

and subsequent pickling in nitrogen to 330 ° C

2-phenylcyclohexanol, 2-cyclohexenj /! cyclohexanol. ι liquid starting product per stone

mrf to « ^S ÄS ^ m? ffi ^
*> NKii a further rinse with phenol and «» * Heaeade the beginning of the Kontalmen ^ eiBto anf 35O ^e C

Example 3 knife of 50mm at a catalyst temperature

. "...,. «5 from 330 to 340 ⁰ C hourly 1800 parts by weight eiai

J2 £ SSJ ^^ T ^ Tt SS? n ^: ^ ** «· * ■ ™ 99.2% of the 2-Cydohexenyl ^ d« placed catalyst · κ weroen in a Konren- bexanoa and 2-CvdofanvKHmrvrinhexanon and a reactor of 400 cm length and thin tube endmch- 0.8% m ^ dSSSSiSa ^ SSSS Ste

passed in vapor form. The results compiled in Table 3 are obtained, with preliminary products, Compounds that cannot be reused and compounds that can be reused correspond to those of Example 2. S table 3

IO

»5

ao

Example 4

About 30 parts by volume of the catalyst prepared according to Example 1 K, which in a tubular reactor according to Example 2 as is, per hour are passed 6 parts by weight vaporous 4-CyclohexylphenoI at 33O ⁰ C. After a shorter one

2-Hy- Reaction product not again
usable
links Again
insert Operating
hour droxy
diphenyl before
Products 7th bare
Connect
fertilize % % 8th 7th 180. 88 1 7th 3 500. 86 1 9 6th 720. 85 1 8th 5 1000. 84 1 8th 7th 1400. 83 1 8th 8th 1600. 82 1 8th 9 2400. 70 1 21

The main reaction product obtained is 4-hydroxydiphenyl. Its proportion in the reaction mixture is after an operating time of the contact from 550 hours constant about 56%.

Example 5
(Comparative example)

Over 30 parts by volume of a catalyst prepared according to Example 1 of US Pat. No. 2,640,084 are in a tube reactor (tube diameter: 17 mm) at a catalyst temperature of 330 ° C per hour 6.0 parts by weight of the starting product used in Example 2 passed in vapor form. The results compiled in Table 4 are obtained, precursors not being reusable Compounds and reusable compounds correspond to those of Example 2.

2-Hy-
droxydi-
phenyl Reaction products not
again
insert
bare ver Again
insert
bare ver
ties Selek
activity Operating
hour % before
Products ties 7th 7th 51 % 14th 16 61 1, -16. 30th 19th 11 41 51 17th-40th 18th

Claims (3)

Patent claims: 1. Nickel, chromium, aluminum, copper and alkali in a proportion of the metals of up to 60: 6.8 to 17.1: 1.6 to 8.0: 0.05 to 1.0: 0.65 to 3, 4-containing dehydrogenation catalyst, produced by adding an alkali metal compound to the base material containing nickel, chromium, aluminum and copper obtained by precipitation, subsequent drying and shaping, reduction at elevated temperature with hydrogen and, if necessary, subsequent treatment with CO ₈ in the heat, characterized in that that a) the base mass with alkali sulfate and / or alkali carbonate as alkali compound in the corresponding amount is impregnated, b) the impregnated and dried catalyst mass into bodies with a bulk density * ° is deformed from 0.8 to 1.6 g / ml, in particular 0.9 to 1.4 g / ml, c) the resulting catalyst moldings at temperatures between 350 and 420 ⁰ C initially with about half to double the ^{equivalent amount of hydrogen calculated for the 3S} reduction of the nickel compounds to metallic nickel and optionally the chromium (VI) compounds to compounds of trivalent chromium within 1 can be reduced to 4 hours, and d) either at the earliest one week after process stage c) the shaped catalyst pieces with about 2 to 10 times that for the reduction of the nickel compounds of the catalyst tors to metallic nickel! «calculated the equivalent amount of hydrogen within 1 to 4 hours at temperatures between 350 and 420 ⁰ C to a content of metallic nickel in the catalyst of about 10 to 35 percent by weight or the catalyst moldings are immunized after process step c), ground and again to moldings with a bulk density of 0 , 8 to 1.6 g / ml are deformed ^4S and then with about 2 to 10 times that for the reduction of the nickel compounds of the catalyst to metallic nickel! calculated equivalent amount of hydrogen is further reduced within 1 to 4 hours at temperatures between 350 and 42O ⁰ C up to a content of the catalyst to metallic nickel of about 10 to 35 weight percent will. ss 2. A process for the preparation of a dehydrogenation catalyst containing nickel, chromium, aluminum, copper and alkali according to claim 1 with a ratio of the metals nickel to chromium to aluminum to copper to alkali metal from 40 to: 6.8 to 17.1: 1.6 to 8.0: 0.05 to 1.0: 0.65 to 3.4, the base mass obtained by precipitation and containing nickel, chromium, aluminum and copper mixed with an alkali metal compound, then dried and shaped, at an elevated temperature with hydrogen reduced and optionally then _{treated with CO 1} in the heat, characterized in that a) the base mass with alkali sulfate and / or alkali carbonate as alkali compound in the impregnated in the appropriate amount, b) the impregnated and dried catalyst mass into bodies with a bulk density deformed from 0.8 to 1.6 g / ml, in particular 0.9 to 1.4 g / ml, c) the catalyst shape obtained; -? e at temperatures between 350 and 4>. C first with about half to double that for the reduction of the nickel compounds to metallic nickel and optionally the Chromium (VI) compounds to compounds of trivalent chromium calculated equivalent amount of hydrogen within 1 to 4 hours reduced, and d) either at the earliest one week after process stage c) the catalyst shapes with about 2 to 10 times the equivalent amount of hydrogen calculated for the reduction of the nickel compounds of the catalyst to metallic nickel within 1 to 4 hours at temperatures between 350 and 420 ⁰ C up to one The metallic nickel content of the catalyst is further reduced by about 10 to 35 percent by weight or the shaped catalyst pieces are immunized after process step c), ground and reshaped to form shapes with a bulk density of 0.8 to 1.6 g / ml and then with about the 2- to 10 times the equivalent amount of hydrogen calculated for the reduction of the nickel compounds of the catalyst to metallic nickel within 1 to 4 hours at temperatures between 350 and 420 ^° C. to a metallic nickel content of about 10 to 35 percent by weight in the catalyst. 3. Use of a catalyst according to claim 1 for the production of hydroxydiphenyl by catalytic dehydrogenation of compounds and / or mixtures of compounds that consist of whole and / or partially hydrogenated hydroxydiphenyl.