FR2498477A1 - Regeneration of zeolite-noble metal hydrocracking catalyst - including water-vapour treatment between coke oxidn. and redn. - Google Patents

Abstract

Zeolitic catalysts contg. a hydrogenating metal are regenerated as follows: after use in hydrocarbon conversions, esp. hydrocracking. (i) the coke is burnt off at a temp. of 300-600 deg.C in an inert gas with an increasing proportion of O2; (ii) after cooling to a temp. of 0-250 deg.C, the catalyst is hydrated by treating with water vapour; (iii) after purging, the catalyst is treated with H2 at increasing temps. in the range 150-600 deg.C. In a heavily deactivated catalyst, (i) and (ii) may be sepd. by (ia) treatment with NH3 vapour to dissolve and disperse the metal. The zeolite is pref. a zeolite Y or mordenite (both with replacement of most of the alkali ions with H(+), alkaline earth or rare earth), erionite, offretite, ZSM 5 or ZSM 11. It pref. contains a Gp. Ib, IIb or VIII metal, esp. Ni, Pd and Pt. Inclusion of (ii) gives a catalyst of improved performance, and esp. stability.

Description

 The present invention relates to a process for the regeneration and rejuvenation of hydrocarbon conversion catalysts, these catalysts comprising (a) a support based on a zeolite, generally acidic, mixed or not with a matrix, and (b) at least one rital , deposited on the support and selected in one of the groups of the period classification as elements, in particular a metal of groups IB (copper, silver, gold) or II.B (in particular zinc and cadmium) or VIII (eg nickel, palladium, platinum, rhodium or iridium).

 These catalysts can advantageously be used, in the presence or absence of hydrogen, for the conversion of various fillers into lighter products and / or products of the same molecular masses but of different distribution and / or in products which have been freed from undesirable compounds. . It is thus possible to cite the conversion of heavy charges, such as distillates or vacuum gas oils, e. lighter fractions consisting mainly of gasoline or kerosene. The conversion of various charges (from light loads such as naphthas to heavy loads such as vacuum distillates) into light gases such as propane and butane, the selective hydrocracking removal of normal paraffins from various fillers, the treatment of gasolines to improve the octane number, the treatment of gas eyelashes to improve the pour point. Mention may also be made of toluene disproportionation and xylene isomerization or mixture of xylenes and ethylbenzene.

 The usual metal tensors in these zeolites are usually from 0.01 to 10%, by weight, when the metal is, for example, silver or copper or zirc or cadmium or nickel and 0.0 and 2.5%, by weight, when the metal is for example palladium or platint or rhodium or iridium.

 The zeolites to which the present invention applies are in particular zeolites A, X and Y, mordc-rite, offretite, erionite, ferrierite, clinoptilolite, zeolites L and A zeolites ZSM5 and ZSM11. This list is however not limiting and the regeneration-rejuvenation technique, which is the subject of the present invention, applies to the other synthetic zeolites which are naturally occurring. The zeolites are generally obtained by replacing most of the alkali ions with at least one of the following cation groups: H + protons, alkaline earth metal ions, and rare earth metal ions. containing at least one of the metals taught above, is generally diluted in an inert matrix which may be, for example, aluminum, silica-alumina, silica-magnesia, natural or synthetic clay, etc. ..

As explained in various publications (eg
Oil and Gas Journal, July 29, 1974, pp 137-143) and patents (USP 3,287,257, 3,357,915, 3,692,692, 3,835,028, 3,849,293, 3,899,441, 4,166,867, 4,139,433, 4,055,482 and 4,148,750. The loss of activity of these types of catalysts during operation is due to two main causes: (a) reduction of acidity and / or (b) decrease of hydrogenation function.The first cause results from the coking of the catalyst or the poisoning of the acid function by various basic compounds contained in the feed, such as alkali metals or nitrogen compounds of high molecular weight (in particular nitrogenous bases containing several aromatic nuclei for example) .The second cause results from the poisoning of the metal by coking or sintering metal Coking and metal sintering are the main causes of catalyst deactivation.

 The main regeneration techniques mentioned in the patents and / or the literature relate to the cracking or hydrocracking catalysts of heavy cuts in gasoline and kerosene which contain palladium deposited on zeolite Y acid.

Among the main publications or patents mentioned above one can distinguish two main types of techniques making it possible to recover the properties of the catalyst:
the so-called "in situ" techniques which are, most often, implemented when the catalyst deactivation is faulty or normal. The deactivation is then largely due to the coke deposit on the zeolite. The catalyst is then regenerated directly in the industrial unit.

 the so-called "ex situ" techniques which are used when the deactivation of the catalyst is important, which is the case when the metal function has been forcibly damaged. In this case, the catalyst is removed from the hydrocracking unit and is "re-depleted" in facilities specifically designed for this purpose.

 The regeneration of "coked" catalysts is carried out conventionally by progressive combustion of the coke in a stream of air diluted with an inert gas, which is most often nitrogen. When most of the coke has been removed, a stream of clean air is sometimes passed over the catalyst at a temperature of between about 400 and 600 C.

 The rejuvenation of strongly deactivated catalysts is more complex and the main techniques proposed are described in some of the patents cited above. The proposed techniques are for the most part aimed at redispersing the hydrogenating metal which has gathered in the form of particles of the order of about 3 to 5 nm (30 to 50%) or more, as a result of severe walking conditions or walking incidents (presence of high temperature water vapor on the catalyst, in particular).

 U.S. Patent 3,287,257. relates to the regeneration-rejuvenation of a zeolitic hydrocracking catalyst whose metal is present in particles of up to 3 nm (30 °): the metal is redispersed by high temperature oxidation (316 to 649 ° C.) previously sulphurized catalyst in the presence of an oxidizing ga containing a slight water-jet partial pressure of 0.005 to 0.5 psi.a.

 U.S. Patent 3,357,915 advocates the adoption of the following cycle of operations: stripping of the deactivated catalyst, reduction in hydrogen at 343 ° to 70 ° C. and high temperature oxidation to remove coke.

U.S. Patents 3,692,692. and US 3,835,028. claim the following technique of rejuvenation of a metal redispersion hydrocracking catalyst present in the form of particles of 50 or more, in the deactivated catalyst
-1) contacting the catalyst in the oxidized or sulphurized state with this water or water vapor and ammonia below 1500C.

 2) drying and calcination.

 - 3) placed in contact with an aqueous solution of an ammonium salt.

 - 4) drying.

 The order of operations 1 and 3 can be reversed.

 U.S. Patent 3,849,293. recommends a technique similar to the previous one: the two operations 1 and 3 above are carried out in a single step on the deactivated catalyst in the oxidized or sulphurized state.

U.S. Patent 3,899,441. mentions the following technique of redispersion repressing of the agglomerated metal in the form of particles of less than 5 nm (5G) in the deactivated catalyst
- 1) contacting the regenerated catalyst by burning the coke, so in the oxidized state with water or water vapor and ammonia below Ce 150 C.

 - 2) drying and calcination.

 U.S. Patent 4,166,867. n.tionne technique of rejuvenation of a palladium-containing hydrocracking catalyst, deactivated by contact with oxygen-free nitrogen above 93 C; this technique consists in calcining the catalyst between 2C4 and 650 C with an oxygen-containing gas before subjecting it to a reduction by hydrogen.

U.S. Patent 4,139,433. discloses a rejuvenation technique derived from those of US Patents 3,692,692., 3,835,028., 3,849,293. and 3.899.44i., wherein the catalyst in the oxide or sulphide state is subjected to the following treatments:
- 1) placed in contact with an ammoniacal solution.

 - 2) elimination of the solution.

 - 3) drying and calcining between 2600C and 510C while maintaining a water vapor partial pressure of less than 10 psi.

In the text of this patent, however, it is recommended not to use air with a dew point greater than -6.7 ° C (ie 0.3% volume;) to dry and calcine the catalyst.

 U.S. Patent 4,055,482. discloses a regeneration technique of a deactivated hydrocracking catalyst, wherein the catalyst is contacted with an aqueous solution containing an ammonium salt at a pH of 4.5 to 6.5.

 U.S. Patent 4,148,750. discloses the contact of a deactivated catalyst in which the catalyst is agglomerated with a solution of ethylenediaminetetraacetic acid.

 L; The present invention relates to a novel method for the regeneration and / or rejuvenation of a catalyst containing at least part of the zeolite material, which method consists essentially in producing a combustion of the catalyst followed by a hydrogen-treatment of the catalyst and characterized in that between the two combustion and reduction operations, steam treatment is carried out at a relatively cool temperature. This method is ideally suited for the in-situ rejuvenation of a relatively low deactivated catalyst ("weak" deactivation).

For a "strongly" deactivated catalyst, in the method indicated above, the catalyst should be treated, after combustion, not directly with water vapor, but first with a mixture of steam and steam. water and ammonia; then, a calcination step will be carried out before proceeding with a steam treatment and then a hydrogen treatment.

Finally, if the catalyst had been very strongly damaged by the course of the reaction that it catalyzed, it is advisable to regenerate it "ex situ", by an appropriate method and particularly adapted to such a spent catalyst, this method can then be followed.
of a treatment carried out according to the process of the present invention.

More specifically, the present invention relates to @n pr @ -
regeneration-rejuvenation process of a hydro conversion catalyst
carbides containing at least partly a zeolite on which is
deposited at least one metal selected from groups IBII.B. and VIII of
the periodic table of elements, in which process:
(a) a catalyst, at least partially deactivated, is treated
between 300 and 600 C, first with a dry inert gas containing 0.5 to 2%
volume of oxygen, then by an inert gas containing between 2 and
About 25% oxygen (clean air for example), in order to achieve the
combustion of the coke deposited on the catalyst (this combustion step
can be done by gradually increasing the temperature, by
bearings for example),
(b) the catalyst is then cooled in an atmosphere
a dry inert gas containing 0.5 to 25% by volume of oxygen (e.g.
in dry air, pure or diluted with an inert gas), by circulation of
said inert gas until the catalyst temperature is cospri-
between 0 and 250 ° C and preferably between 10 and 100 ° C, for example
at room temperature,
(c) the catalyst is then swept, at a temperature
between 0 and 250 C and preferably between 10 and 100 C, by
Example at room temperature, with pure water vapor or diluted in an inert gas and / or air (water vapor content: 0.5 to 100% by volume) for a period of time sufficient to partially or completely hydrate the catalyst, ie to include between about 0.2 to 25% by weight of water and preferably 1 to 15 (a rate of 25% generally corresponds to the degree of saturation of water in the zeolitic mass).

(d) the at least partially hydrated catalyst is ha
inert gas at a temperature of less than 250 ° C. and preferably less than 100 ° C.,
(e) the catalyst is then subjected to treatment with pure or dilute dry hydrogen, at a temperature which is initially less than 1500 ° C. or preferably less than 100 ° C., and which is progressively raised to between 1500 and 600 ° C. and preferably between 200 and 4500C, while ensuring that above 200 C, the dew point of the gas measured at the outlet of the reactor under normal conditions of pressure and temperature, is less than -100 ° C (approximately 0.25 ° C). % vol.) and preferably below -200C (ie about 0.1 7 vol.), the total duration of the hydrogen treatment being between about 5 minutes (10 minutes for example) and about 60 hours, (10 hours for example).

If the wear of the catalyst is pronounced, the regeneration-reactivation of the catalyst is carried out according to a process in which
(a) the deactivated catalyst is treated as indicated above between
300 and 6000C, first with a dry inert gas containing 0.5 to 2%.
volume of oxygen, then by a dry inert gas containing between 2 and
About 7% oxygen (eg clean air), in order to induce
combustion of the coke deposited on the catalyst, in which process
then, before performing step (b) described above,
(a) the catalyst is cooled, by any suitable means, to a temperature of
less than 1500C,
(fi) the cooled catalyst is subjected between 0 and 1500C at one sweep
by air or an inert gas with a volume usually of 0.5
60% water vapor and 0.1 to 50% ammonia (and the complement to
100% for example in the form of air), for a time and with a
sufficient flow to saturate the catalyst with ammonia
in order to allow a substantially complete dissolution of the elements
the catalyst and an optimal redispersion of the
metals in the catalyst,
(d> the catalyst is then calcined under flow of a dry inert gas
containing 2 to 30% oxygen, generally under a dry air flow, at
a temperature which initially is between about 100 and
1800C, in order to eliminate as much as possible the water contained in the catalyst,
the temperature is then raised slowly and preferably progresses
until it reaches a maximum value of
between 200 and 7000C and preferably between 250 and 6000C, the
maximum temperature is then maintained during a
period between a few minutes (10 minutes for example) and
a few dozen hours (50 or 20 hours for example).

After this last stage, the catalyst is treated according to
the invention as indicated in paragraphs (b) and (c) (d) and (e) ci
above.

the regeneration-reactivation method according to the invention
particularly suitable for catalysts containing a zoolite
acid and in particular wherein the acidic zeolite is a zeolite
Y or a mordenite. The acidic zeolite can also be offretite,
Erionite, ZSM5 and ZSM11. Preferably, most of the
alkaline ions, in the acidic zeolite used, has been replaced by
at least one of the cations of the following three categories: H ions, ions
alkaline earths and rare earth metal ions.

The operation, according to the invention of rewetting the
relatively cold temperature catalyst, before the reduction step
of the catalyst, ie of its treatment with hydrogen, is translated
by a very clear gain on the performances of the catalyst and in particular on
its stability, as shown by the various examples presented
after which are given for illustration only and do not limit
the scope of the present invention.

 The catalysts thus regenerated are suitable for hydrocarbon hydrocracking reactions, which reactions are generally carried out at a temperature between about 260 and 5300C and a pressure of between about 0.8 and 25 MPa. The conversion conditions include a liquid hourly space velocity or VIISL, or volume per hour of liquid charge at 15 C per volume of catalyst, from about 0.1 to 10.0 agent, preferably an upper limit of 4.0. about and a hydrogen flow rate of about I to 20 moles / mole of filler.

Example 1: It is proposed to hydrocrack a gas oil on a catalyst which contains 0.48% by weight of palladium deposited on a mixture containing 50% by weight of a zeolite in stabilized HY form and 50% by weight. alumina. The treated feedstock is a heavy gas oil having the following main characteristics:
starting point: 3500C; density at 20 ° C: 0.858;
refractive index at 700C = 1.4561; viscosity at 98.90C =
4.25 csk (4.25 x L0-6 m2 / sec); S content = 60 ppm, grade
in nitrogen = 250 ppm (ex n hexylamine).

Before starting the test, the catalyst is reduced, in the unit, under hydrogen until a temperature of 450 C for 2 hours, then is always cooled under hydrogen to 3000C. Then we inject into
the hydrogen 2% by weight of ammonia relative to the catalyst, under
form of n-butylamine.

We then proceed to the injection of the load in the condi
following
T = 3400C; P = 60 bar; LHSV (or PPH) = 2; hydrogen ratio /
charge = 500 liters of hydrogen gas per liter of liquid charge.

The level of conversion of the load is identified by the
density of the liquid recipe (liquid effluent) collected at 300C.

After 36 hours of revving, this density is 0.770 which
corresponds to a conversion of around 72-75% into 250 products (this is
to say boiling before 2500C). The temperature is kept constant
and we follow the evolution of the density during 605 hours (approximately
25 days). The results are reported in Table I
TABLE I

<tb><SEP> Time <SEP> (h) <SEP> 36 <SEP> 104 <SEP> 210 <SEP> 305 <SEW> 490 <SEP> 605
<tb> density <SEP> of <SEP> the <SEP> 0.770 <SEP> 0.772 <SEP> 0.767 <SEP> 0.773 <SEP> 0.778 <SEW> 0.781
<tb> recipe <SEP> liquid
<tb><SEP> to <SEP> 20 "C <SEP>
<Tb>
After 605 hours, 500 ppm of nitrogen in the form of n-hexylamine is introduced into the feed; the temperature is then raised to 370 C to find a density close to 0.77, ie approximately the same conversion. We remain 10 days in these new conditions and we observe a slight increase in the density which goes from 0.773 to 0.781 (0.781 corresponds to conversion to 250 neighbor from 65 to 67%.

 The test is then stopped, the catalyst discharged and divided into two identical parts. The cystic acid cyst content is 2.5% by weight.

Example 2: The regeneration of the catalyst according to the present invention was carried out.

 The first part of the catalyst, isolated at the end of Example 1 is recharged in the unit and is regenerated by burning the coke, first in diluted air (20% air - 80% nitrogen). ) by raising the temperature gradually to 500 C and observing intermediate stages of 30 minutes each at 350 C, 400 C, 450 C and 5000C, then under pure air for 2 hours at 500 C.

 The reactor is then cooled to ambient temperature (20 ° C.) and is swept by air saturated with humidity at room temperature (20 ° C.) for a time sufficient to deposit on the catalyst approximately 8 to 10% by weight. moisture weight. The catalyst is then purged under a high nitrogen flow for 1 hour.

A pure hydrogen sweep is then carried out at a rate of 2 lSh per gram of catalyst at room temperature under a total pressure of 2 bars (absolute) for 30 minutes, and then the temperature is gradually raised to 300. C in 30 minute increments each at 50, 100, 150, 200, 250 C. and 300 C. From 300 C, the temperature is gradually increased without
temperature of 450 C that is maintained for 1 hour. From
200 C, it is ensured that the water content of the gas at the outlet of the reactor
corresponds to a dew point below -25 C (less than 0.06 7
flight).

The catalyst thus regenerated is then started and tested at 3500C with the other conditions identical to those described in Example 1. The results obtained during this new test of 605 hours were reported in Table II below.
TABLE II

<tb><SEP> Time <SEP> (h) <SEP> 36 <SEP> 104 <SEP> 210 <SEP> 305 <SEW> 490 <SEP> 605
<tb> 3sensitivity <SEP> of <SEP><SEP> 0.775 <SEP> 0.775 <SEP> 0.778 <SEP> 0.779 <SEP> 0.785 <SEP> 0.789
<tb> recipe <SEP> liqui
<tb> e <SEP> from <SEP> to <SEP> 200C
<Tb>
It is noted that the regenerated catalyst has a slightly lower activity than the new catalyst, but however its stability is on the other hand quite comparable to that of the new catalyst since we always obtain suitable results after 605 hours of operation.

Example 3 (comparative).

 The second portion of the catalyst coke isolated at the end of Example 1, is recharged in the unit and is regenerated by burning the coke under the same conditions as those used in Example 2.

 The reactor is then cooled to room temperature and swept for 1 hour under a high flow of dry nitrogen. The hydration step of the catalyst described in Example 2 is therefore not carried out here.

 The reduction of the catalyst is then carried out under hydrogen in the neat conditions as in Example 2.

 The catalyst thus regenerated is then started and tested at 3500C with the other operating conditions described in Example 1. The results of this new test are presented in the following Table III; the operation is stopped after 305 hours because of the insufficient results obtained at this stage.

TABLE III

<tb><SEP> Time <SEP> (h) <SEP> 36 <SEP> 104 <SEP> 210 <SEP> 305
<tb> Density <SEP> of <SEP><SEP> 0.783 <SEP> 0.790 <SEP> 0.801 <SEP> 0.812
<tb> recipe <SEP> liqui
<tb> from <SEP> to <SEP> 2O0C <SEP>
<Tb>
It can be seen that the catalyst regenerated according to a conventional technique not in accordance with that of the present invention is clearly less active and less stable than the regenerated catalyst according to the present invention.

Example 4 The regeneration according to the present invention is carried out of a highly deactivated catalyst; A catalyst identical to that used in Example 1 is placed for 2 days under the following severe conditions in order to deactivate it.
charge identical to that of example 1 but containing
1500 ppm of nitrogen in the form of n-hexylamine.

T = 410 C
other operating conditions identical to those of
Example 1

 Under these severe conditions, the density of the liquid recipe changes rapidly from 0.785 after 24 hours, to about 0.795 after two days.

 The catalyst thus deactivated is discharged from the unit and divided into two identical batches. The coke rate on this catalyst is 5.6% wt. The electron microscopic examination of this catalyst shows the presence in large quantities of palladium particles having sizes greater than 4 nm (nanometers).

The first batch of the catalyst is recharged in the reactor of the unit where regeneration-rejuvenation according to the present invention is carried out, which consists in carrying out the following operations
1 / The catalyst is regenerated by combustion of the coke in the
same conditions as those of Example 2.
reactor at a temperature of 70 ° C.

2 / The catalyst is swept by air heated to 700C which is
bubbled in a strongly ammoniacal solution
at the same temperature, and this until the catalyst
saturated at this temperature with the ammonia solution.

The sweep is stopped and the catalyst is left in contact
with the solution absorbed for 5 hours at 700C.

3 / The catalyst is swept by a strong flow of dry air in
gradually increasing the temperature up to 250 ° C
observing steps of 30 minutes each at 100 "C, 1500C
200 and 250 ° C. Then the temperature is gradually increased
up to 4500C and leave two hours at this temperature. We
then cooled the reactor to room temperature.

4 / The catalyst is swept by a high air flow saturated with humi
at room temperature under the conditions described,
in example 2.

5 / The reactor is purged under nitrogen and then the reduction is carried out
of the catalyst from room temperature to 4500C as indicated
in example 2
The catalyst thus regenerated is then started and tested at 3500C under the same conditions as those of Example I. The results obtained during a test of 505 hours are presented in the table.
IV next
TABLE IV

<tb><SEP> Time <SEP> (h) <SEP> 36 <SEP> 104 <SEP> 210 <SEP> 305 <SEW> 490 <SEP> 605
<tb> Density <SEP> of <SEP><SEP> 0.781 <SEP> 0.780 <SEP> 0.783 <SEP> 0.788 <SEP> 0.789 <SEP> 0.790
<tb> recipe <SEP> liquid
<tb> to <SEP> 20 C
<Tb>
It can be seen that the catalyst thus regenerated has a behavior very close to the regenerated catalyst in Example 2, despite the severe deactivation that it had undergone in this experiment.

Example 5 (comparative)
The second batch of the catalyst subjected to the deactivation treatment of the preceding example is recharged in the reactor of the unit and is subjected to a regeneration-rejuvenation defined by a sequence of operations comprising, in the same order, the steps of the Example 4 above with, however, removal of the 4th stage (humidification of the catalyst).

 The catalyst thus regenerated is then started and tested at 350 under the test operating conditions of Example 1.

The results obtained are presented in the following Table V
TABLE V

<tb><SEP> Time <SEP> (h) <SEP> 36 <SEP> 104 <SEP> 210 <SEP> 305
<tb> Density <SEP> of <SEP><SEP> 0.780 <SEP> 0.783 <SEP> 0.798 <SEP> 0.809
<tb> recipe <SEP> liquid
<tb> to <SEP> 20 C
<Tb>
It is seen that the regenerated catalyst according to a conventional technique different from that of the present invention has a suitable behavior for about 100 hours but is then significantly less active and less stable than the regenerated catalyst according to the method described in Example 4.

Claims (9)

1 / A process for the regeneration or rejuvenation of a hydrocarbon conversion catalyst containing at least partly a zeolite on which is deposited at least one metal selected from groups IB, IIB and VIII of the periodic table of elements, process in lebel  a) a catalyst, at least partially deactivated, is treated between 300 and  6000C, first with a dry inert gas containing 0.5 to 2% by volume  of oxygen, then with a dry inert gas containing between 2 and 25%.  of oxygen for the purpose of burning the coke deposited on the  catalyst,  b) the catalyst is then cooled in an atmosphere of a gas  dry inert material containing 0.5 to 25% by volume of oxygen by circulation of  said inert gas until the temperature of the catalyst is  between 0 and 2500C,  c) the catalyst is then swept at a temperature between  O and 2500C, by a stream of water vapor or by a current of at least  a gas consisting of an inert gas or air and containing from 0.5 to 100 Z  volume of water vapor, for a time sufficient to hydrate by  the catalyst, ie to include  between about 0.2 to 25% by weight of water,  d) the at least partially hydrated catalyst is swept by a  inert gas at a temperature below 2500C,  e) the catalyst is subjected to a dry, pure hydrogen treatment  or diluted, at a temperature which is initially below 1500C, and  which is progressively raised between 1500 and 6000C, while ensuring  above 200 C, the dew point of the gas measured at the outlet  the reactor under normal conditions of pressure and temperature,  less than -100C (ie approximately 0.25 7. vol), the total duration of the  hydrogen treatment being between about 5 minutes and  about 60 hours. 2 / A method according to claim 1, for the regeneration of a catalyst, in which  a) the deactivated catalyst is treated at between 300 and 600 ° C,  first by a dry inert gas containing 0.5 to  2% by volume of oxygen, then by a dry inert gas containing  between 2 and 25% of oxygen, in order to provoke the com  bombardment of the coke deposited on the catalyst, in which process  then, before carrying out step (b) described in the  tion 1,  a) the catalyst is cooled, by any appropriate means, to a  temperature below 1500C,  ss) the cooled catalyst, is subjected between 0 and 1500C, at a  by air or an inert gas containing, in volume,  0.5 to 60% of water vapor and 0.1 to 50% of ammonia,  for a time and with a flow sufficient to saturate the cat  ammonia lyser to allow substantially  complete metal elements of the catalyst and redisper  optimum concentration of the metal or metals in the catalyst,  g) the catalyst is then calcined under a flow of an inert gas  dry matter containing 2 to 30% oxygen, generally under airflow  dry, at a temperature which initially is between  100 and 1800C, in order to eliminate as much water as  the catalyst, the temperature being then raised until  that it reaches a maximum value between 200 and 7000C,  the said maximum temperature being then maintained during a  period between 5 minutes and 60 hours before  to make reps (b) to (e) of the revenge  1. 3 / A method according to one of claims 1 and 2 wherein during step (b), the catalyst is cooled until it is at a temperature between 10 and 1000C, the steps (c ) and (d) being then carried out at this temperature.  4 / A method according to claim @ wherein the catalyst is cooled until it is cooled to room temperature of the order of 20 C, steps (c) and (d) being carried out thereafter at this temperature . 5 / A method according to claim 3 wherein the catalyst is a hydrocarbon hydroconversion catalyst containing at least partly an acidic zeolite. 6. The process as claimed in claim 5, in which the zeolite acid is a Y zeolite, most of the alkaline ions have been replaced by at least one cation selected from the group consisting of H + ions, alkaline earth ions and ions. rare earths. 7 / A method according to claim 5 wherein the acidic zeolite is a mordenite most of the alkali ions has been replaced by at least one cation selected from the group consisting of H + ions, alkaline earth ions and metal ions rare earths.  8 / The method of claim 5 wherein the acidic zeolite is selected from the group consisting of erionite, offretite, ZSM5 and ZSM 11. 9 / A method according to one of claims 1 to 8 wherein the metal, deposited on the zeolite, is selected from the group consisting of nickel, palladium and platinum.