JPH05245393A - Regeneration of deactivated viii group noble metal catalyst - Google Patents

Abstract

PURPOSE: To make regeneration and reactivation of a deactivated catalyst possible by bringing the catalyst into contact with halogen and carbon dioxide gases in a redispersing step of noble metal and keeping an amount of carbon dioxide at a specified partial pressure. CONSTITUTION: Cokes are removed from a catalyst, and redispersion of noble metal is carried out by bringing the catalyst into contact with an origin of oxygen which is co-present with a halogen gas or halide-contg. gas and carbon dioxide in a reactor. Wherein, an amount of carbon dioxide is kept at a partial pressure of at least 2 kPa. The catalyst is then stabilized by a treatment with inert gas or oxygen-contg. gas. Carbon dioxide and carbon monoxide are removed at a partial pressure of <0.5 kPa, to reduce the catalyst chemically. Thereby, the catalyst exhibits higher selectivity for preparation of a desired arom. compd. in a naphtha modification procedure, and also exhibits long life and keeps a sufficient activation level for a long period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION

A. FIELD OF THE INVENTION The present invention relates to a method of regenerating and reactivating a coke fouling deactivated catalyst comprising one or more Group VIII noble metals, a refractory support and a binder. These catalysts are commonly used in hydrocarbon conversion processes, especially in catalytic reforming.

B. DESCRIPTION OF THE PRIOR ART Some materials have been used as hydrocarbon conversion catalysts in processes such as reforming, catalytic dewaxing, alkylation, oxidation and hydrocracking. Examples of catalysts useful in these processes include materials comprising catalytically active Group VIII metals, typically platinum, and optionally rhenium or tin, supported or impregnated on a support. Usually the support is alumina, but more recently zeolites such as X and Y type zeolites have been used. L-type zeolite, especially cation exchange L
Type zeolites have also been suggested as suitable carriers.

Among the hydrocarbon conversion processes, catalytic reforming in the presence of hydrogen is one of the most important ones. Catalytic reforming is an essential oil process intended to increase the octane number of naphtha.
The naphtha feed is typically applied to a platinum-containing catalyst supported on a refractory material at about 2 to about 20 reforming conditions well known in the industry, such as elevated temperature and pressure, in the presence of hydrogen gas. Passed in a hydrogen to hydrocarbon molar ratio. Reforming methods include isomerization, dehydrogenation of naphthenes to aromatics, dehydrogenation of paraffins to olefins, dehydrocyclization of paraffins and olefins to aromatics, paraffins to gaseous hydrocarbons such as methane or ethane. It involves cracking, and several different types of reactions, including the formation of unavoidable coke, the latter being deposited on the catalyst. Ideally, the reforming process minimizes the hydroreforming cracking of paraffins and maximizes the reactions that result in the formation of more useful products, especially the dehydrocyclization and dehydrogenation to aromatics.

During the reforming process, the activity of the catalyst gradually diminishes due to the accumulation of coke, eventually requiring its regeneration and reactivation. Some steps are required to regenerate and reactivate the catalyst.

The first stage is the regeneration of the catalyst by removing the coke deposits. A catalyst is typically used in the presence of dilute oxygen.
Coke is removed by heating at a flame front temperature of 0-540 ° C. Some water vapor may be present during this regeneration stage. U.S. Pat. No. 4,354,925 uses a gas mixture of oxygen and carbon dioxide, the presence of which gas mixture allows the use of higher oxygen concentrations in the combustion gas, thereby making coke combustion faster. It is disclosed that it is possible to finish. This regeneration step can be preceded by flushing the system with, for example, hydrogen or nitrogen gas to remove residual hydrocarbons.

The high temperatures used for the regeneration result in the agglomeration of the metal particles and, when the support is a zeolite, the migration of the metal particles from the zeolite channel and thus the deactivation of the catalyst, so that after coke burn-off the catalyst is It is usually subjected to a reactivation step in which the metal particles are redispersed on the carrier material. Typically, this involves treating the catalyst with a chlorine-containing gas or a gas that liberates chlorine, usually in the presence of oxygen and steam, often referred to as an oxychlorination step.

The catalyst is then a reducing gas, typically hydrogen,
To reduce the metal chlorides formed during the oxychlorination step to elemental metal particles. The catalyst is then used again in the reforming process.

However, it has been found that the above regeneration and reactivation operations, especially for platinum containing zeolite catalysts, often do not reactivate to activation levels exhibited by or close to that of the new catalyst.

[0009]

SUMMARY OF THE INVENTION The present invention relates to an improved method for reactivating catalysts. Accordingly, the present invention involves (a) removing substantially all coke from the catalyst, (b) redispersing the precious metal (s) on the support, and (c) chemically reducing the catalyst, Dispersing step (b) is carried out by contacting the catalyst in the reaction vessel with a halogen or halide containing gas and carbon dioxide gas, the amount of carbon dioxide substantially contacting the catalyst with the halogen or halide containing gas. A partial pressure of at least 2 kPa is maintained in the reaction vessel during the period of at least 1
Provided is a method of regenerating and reactivating a coke fouling deactivated catalyst comprising a Group VIII noble metal, a carrier and a binder.

We have found that the presence of carbon dioxide during the redispersion stage of the catalyst regeneration and reactivation process enhances the activity and thus the performance of the catalyst. The catalysts which have been subjected to the process according to the invention show a high selectivity towards the formation of the desired aromatic compounds in the naphtha reforming process and also a high lifetime, ie a sufficient activation level for a longer time than the catalysts regenerated by conventional processes. To maintain. The process according to the invention has the particular advantage for the regeneration of Group VIII containing catalysts supported by zeolitic materials.

[0011]

DETAILED DESCRIPTION OF THE INVENTION In the more specific embodiments of the invention described below, the gas stream used in each step is a balance of inert gas such as helium, argon or nitrogen (water, hydrogen, oxygen or chlorine) that does not interfere with the process. Not source). Water is preferably present in the gas stream at each stage.

Generally, the coke removal step (a) comprises the deactivated catalyst in an amount of 0-10% by volume of water, based on total flow volume,
Preferably 0.5-5% by volume of water, more preferably 1-
It is carried out by contacting with a gas stream containing 3% by volume of water and oxygen (usually in the form of an oxygen-containing gas such as air) at a temperature of about 380-540 ° C. Preferably this first stage is carried out at two temperatures, the first being about 380-480 ° C.
The second is a high temperature range of about 480 to 520 ° C. The O ₂ treatment at low temperature is preferably performed for a longer time than the second O ₂ treatment. The exact time of heating depends on the temperature used, but is generally in the range of 1 to 10 hours or more. The amount of oxygen used is generally 0.1 to 25% by volume of the gas stream, preferably 0.2 to 1
It is 5% by volume, more preferably 0.5 to 12% by volume.

The redispersion step (b) is carried out with a halogen or halide containing gas (generally referred to below as "halogen gas") and carbon dioxide. The source of halogen gas can be, for example, chlorine gas, carbon tetrachloride or hydrogen chloride. The halogen gas is usually mixed with oxygen, and preferably also with steam, this redispersion stage is commonly referred to as the oxychlorination stage. Examples of suitable oxychlorination stages are: (i) the catalyst in the presence of oxygen in the presence of a gas stream containing 0-10% by volume of water and a chlorine source at a temperature of about 400 to about 530 ° C. for 10 hours. (Ii) heating the catalyst in the presence of a gas stream containing 0-10% by volume of water and a source of chlorine, in the presence of hydrogen (HCl being the source of chlorine,
Except when hydrogen is optional), about 400 to about 530
Heat at 0 ° C. for up to 10 hours, then add catalyst to oxygen 0-.
Up to 7 hours in the presence of a gas stream containing 10% by volume and substantially free of water, or 0 to 10% by volume of oxygen and 0 or more to 1 of water
Up to about 40 in the presence of a gas stream containing 0% by volume for up to 5 hours
Heating at a temperature of 0 to 540 ° C; (iii) steps (ii) and (i) above in that order (i
i) combining without subsequent heating in; (iv) catalyst for 10 hours at a temperature of about 400 to about 530 ° C. in the presence of a gas stream containing 0-10% by volume of water and an effective amount of chlorine. Heating up to.

The source of carbon dioxide can be, for example, pure carbon dioxide gas or a mixture of carbon dioxide and an inert gas fed directly into the reactor in which the catalyst is regenerated. The carbon dioxide source can also be mixed with other gases used during the oxychlorination step, typically halogen gas, oxygen and optional steam. Alternatively, the source of carbon dioxide can be a compound that liberates carbon dioxide, which can be a gas, a liquid or a solid, but is preferably a gas to facilitate its introduction into the reactor. ..

In order to obtain improved catalytic performance, carbon dioxide must be maintained at a partial pressure of at least 2 kPa in the reactor during the period of substantially contacting the catalyst with the halogen gas. For convenience, the introduction of carbon dioxide gas is started almost at the same time as the introduction of halogen gas, and is ended almost at the same time as the end of the halogen gas feeding. Carbon dioxide can be fed into the reactor, for example as a continuous stream of gas or as a pulse of gas if a minimum concentration is maintained. Preferably a continuous flow is used. The carbon dioxide gas leaving the reactor can be recycled and fed back into the reactor, thus providing an economical reactivation method.

Preferably during the oxychlorination step (ie when halogen gas is present) the partial pressure of carbon dioxide in the reactor is between 2 and 35 kPa, more preferably between 4 and 15 kPa.
Is. It is preferred to feed carbon dioxide gas into the reactor as a mixture of carbon dioxide gas and an inert gas such as nitrogen or helium.

Although the invention is not limited to a particular theory, the presence of carbon dioxide can reduce the degree of reaction between the halogen gas and the binder, such as alumina, present in the catalyst, which Appears to inhibit the formation of metal halides such as platinum chloride on the binder material. Thus for the platinum-L zeolite catalyst this results in a good distribution of platinum particles within the L zeolite channel.

After completion of the oxychlorination step, it is generally preferred to remove excess halogen to stabilize the metal particles on the support surface. Typically this is accomplished by continuing to contact the catalyst with oxygen after terminating the flow of halogen gas. For example, the catalyst comprises 0-10% by volume of oxygen and up to 7 hours in the presence of a gas stream substantially free of water, or 0-10% by volume of oxygen and 0 to 10% by volume of water. By heating at a temperature for up to 5 hours in the presence of a gas stream. This additional step is the redistribution step above.
Not required when (ii) is done to be already included in that stage. If desired, the flow of carbon dioxide can be continued during the oxygen stabilization phase and then stopped.

After oxychlorination, the catalyst requires a chemical reduction to convert the noble metal halide formed during oxychlorination to elemental metal. Generally, this reduction is accomplished by contacting the catalyst with a reducing gas such as hydrogen at elevated temperature, optionally in the presence of steam. For example, the catalyst may be treated with water at a temperature of about 350 to about 530.degree.
Heat in the presence of a gas stream containing -10% by volume and a source of hydrogen. The hydrogen concentration is generally 0.5 to 100% by volume, preferably 2 to 20% by volume.

We have also found that the presence of carbon dioxide or carbon monoxide during the reduction step can adversely affect the performance of the resulting catalyst. Therefore, the reduction is preferably carried out in the presence of minimal, if any, carbon dioxide and carbon monoxide. The amount of carbon dioxide and carbon monoxide present during the hydrogen reduction step should not exceed 0.025 kPa partial pressure. It is particularly preferred to eliminate carbon dioxide and carbon monoxide prior to the reduction step when the catalyst support is L zeolite. After the oxychlorination step, if the system is flushed with oxygen as described above, this will result in the removal of carbon containing gas. However, it is also preferable to remove the residual oxygen before introducing the hydrogen gas. Therefore, it is preferable to purge the system with an inert gas such as nitrogen or helium before the start of the reduction step, whether or not oxygen treatment is performed.

Another method of removing carbon monoxide and carbon dioxide before the reduction step is by a pressure-vacuum cycle with an inert gas free of carbon monoxide and carbon dioxide, such as nitrogen. By pressurizing the reactor with an inert gas, the concentration of carbon monoxide and carbon dioxide is reduced by dilution. This method can be combined with a gas purge as described above.

At all stages of catalyst regeneration and reactivation according to the present invention, the reactor pressure is generally 0.1 to 2 MPa.
a, atmospheric pressure for convenience. The gas flow rate is generally in the range of about 1 to about 300 ml per gram of catalyst per minute.

Catalyst supports are, for example, inorganic oxides such as alumina, titanium dioxide, zinc oxide, magnesium oxide, thoria, chromia, or zirconia, zeolites such as faujasite, mordenite, X, Y or L zeolites, clays such as china clay, It can be kaolin, bentonite, diatomaceous earth or other silicon-based material such as silica gel or silicon carbide, or a mixture of one or more of the above. Preferably the support is alumina or zeolite, more preferably zeolite, especially L-type zeolite.

The L-type zeolite can be defined as a synthetic zeolite that crystallizes in a hexagonal system. They have channel-shaped pores that undulate about 7-13 Å in diameter and are in the form of columnar crystals with an average diameter of at least 0.5 microns and an aspect ratio of at least 0.5 (see, eg, US Pat. No. 4,544,544). , 539, the disclosures of which are referenced), as well as other geometries and sizes. L zeolites typically have the general formula: 0.9-1.3 M ₂ / nO: Al ₂ O ₃ : xSiO ₂ : yH ₂ O, where M represents an exchangeable cation and n represents the valence of M. , Y is a value of 0 to about 9, and x is about 5.2 to about 6.9).

A more complete description of L zeolite is given in US Pat. No. 3,216,789, the disclosure of which is referenced.

The L-type zeolite is usually prepared so that M in the above formula is potassium. For example, US Pat. No. 3,2
See 16,789 and 3,867,512. Potassium can be ion-exchanged by treating the zeolite in an aqueous solution containing other cations, as is well known. However, it is difficult to exchange more than 75% of the original potassium cations because some of the cations occupy sites in the zeolite structure that are almost unreachable. At least 75% of the exchangeable cations are selected from lithium, sodium, potassium, rubidium, cesium, calcium and barium. More preferably the cation is sodium, potassium, rubidium or cesium, even more preferably potassium, rubidium or cesium, most preferably potassium. Optionally, the exchangeable cation may comprise a mixture of the above Group IA cations or a mixture of Group IA cations and barium or calcium cations. These mixtures of cations can be achieved, for example, by treating zeolite L with an aqueous solution containing, for example, rubidium and / or cesium salts, followed by washing to remove excess ions. This ion exchange process can be repeated to perform further, but to a lesser extent, ion exchange.

The zeolite catalyst used in the process of the present invention can be made by loading the zeolite with one or more Group VIII metals. Preferably the zeolite is made into shaped particles such as pellets, extrudates, spheres, granules etc. with an inert binder such as alumina, silica or clay before loading. Alumina, especially γ-alumina, is the preferred binder. It should be understood that reference herein to the diameter of the catalyst particles refers to the diameter of the shaped particles, which is preferably from about 1/32 "to about 1/4". Preferably the metal is or comprises platinum, typically about 0.3 to about 1.5% platinum, based on the weight of the zeolite, as disclosed in US Pat. No. 4,568,656. The zeolite is loaded by the above method.

In the loading method of the 4,568,656 patent, the zeolite, typically a pellet or matrix with a binder, is contacted with an aqueous loading solution containing a platinum salt and a non-platinum metal salt for 8-12. A pH value of 5 is given and aged to distribute the platinum salt in the pores of the zeolite, dried and then calcined.

L-zeolite catalysts can be made at various pH levels, and we have found that addition of carbon dioxide during the redispersion stage of catalyst regeneration and reactivation results in platinum deposition on L-zeolite at high pH levels. Rather lower pH (about pH 8 ~
It has been found that a particularly advantageous but slightly improved catalytic performance when carried out under 9) is also exhibited when the zeolite catalysts are produced at these high levels.

The Group VIII noble metal required for catalytic activity is a Group VIII metal of the periodic table of elements selected from osmium, ruthenium, rhodium, iridium, palladium and platinum. Preferably the metal used for this is platinum,
Rhodium or iridium, most preferably platinum,
Examples of suitable bimetallic combinations are platinum-iridium and platinum-
It is palladium. The metals can be present in any desired combination. Rhenium, Group VIIB metal, also contains at least one V
It can be present as long as the Group III noble metal is present, an example being platinum-rhenium.

The amount of Group VIII noble metal present in the catalyst is an effective amount, depending, for example, on the required catalytic activity, ease of uniform dispersion, and type of catalyst support. For zeolites, the crystal size constrains the effective catalyst loading because a highly loaded crystal of zeolite with a large dimension parallel to the channel can easily clog the pores as noble metal agglomerates inside the channel during operation. However, generally, the level of metal present is about 0.1 to about 0.1% of the catalyst.
It will be in the range of 6%, preferably 0.1-3.5%, more preferably 0.1-2.5%, most preferably 0.2-1% by weight. Further, for the zeolite, the amount of metal present is generally about 0.1 to 2.0% by weight of the catalyst if the average zeolite crystallite size parallel to the channel is greater than about 0.2 microns, The parallel zeolite crystallite size is about 1.0-6% by weight, if not greater than about 0.2 microns.

Group VIII noble metals include, for example, ion exchange, impregnation,
It can be introduced on the support by carbonyl decomposition, adsorption from the gas phase, introduction during zeolite synthesis, and adsorption of metal vapors. The preferred method is ion exchange. In some cases,
For example, when the metal (s) is introduced by the ion exchange method, it is preferred to remove the residual acidity of the carrier material by treating the catalyst previously reduced with hydrogen with an aqueous solution of an alkali base, such as potassium carbonate. This treatment will neutralize the hydrogen ions formed during the reduction of the Group VIII noble metal ions with hydrogen.

The activation process according to the invention can also be applied to new catalysts to improve the activity of the new catalysts in the naphtha reforming process. By "new catalyst" is meant a catalyst that has not yet been used in the naphtha reforming process and thus is not coke-contaminated. Therefore, in another aspect, the present invention comprises (a) treating the catalyst with a halogen- or halide-containing gas in the presence of carbon dioxide in a reaction vessel, and (b) chemically reducing the catalyst, at least A method is provided for activating a new catalyst which comprises both a Group VIII noble metal, a support and a binder.

The preferred conditions and embodiments of this other aspect of the invention are as described above for the reactivation process of coke fouling catalysts.

The reduction of the catalyst prior to its use in the reforming step involves the reduction of carbon dioxide and carbon monoxide from 0 to 0, whether or not it has been activated or reactivated in the presence of carbon dioxide.
It has also been found to work favorably in the presence of a partial pressure of 0.025 kPa. More preferably the reduction is carried out in the substantial absence of these carbon containing gases. The presence of high levels of these gases significantly reduces the activity of the catalyst during reforming. This applies to the reduction of both fresh and regenerated catalysts.

Once the catalyst has been reduced, it is advantageous not to expose the catalyst to carbon dioxide and carbon monoxide in an amount above a partial pressure of 0.025 kPa before use in the reforming step.

The invention will now be illustrated by the following examples. Parts and percentages are by weight for solids and liquids and by volume for gases unless otherwise stated. The gas composition is described with respect to the main constituents; the balance composition comprises an inert gas such as nitrogen or helium.

Example 1: The catalyst was prepared as follows: in moles of pure oxide
0.99 K ₂ O: Al ₂ O ₃ : 6.3 SiO ₂ : xH ₂ O,
L with a cylindrical shape and an average particle size of about 2 to 2.5 microns
The zeolite was prepared by the method described in US Pat. No. 4,544,539. Therefore, 23.4 g of aluminum hydroxide was added to potassium hydroxide pellets (8
An alkaline synthetic gel was prepared by dissolving by boiling in an aqueous solution of 51.2 g of 6% pure KOH) to form solution A. After the dissolution, the water loss was corrected. 225 g of colloidal silica [Ludox HS40] in water 19
Another solution, Solution B, was prepared by diluting with 5 g. Solutions A and B were mixed for 2 minutes to form a gel, and immediately before the gel completely hardened, 224 g of the gel was transferred to a Teflon-lined autoclave preheated to 150 ° C and kept at that temperature for 72 hours to crystallize. And then the solid zeolite was separated.

The zeolite was then shaped into 1/16 "extrudates using γ-alumina as a binder. Then P
The zeolite extract was loaded with 0.64 wt% platinum using t (NH ₃ ) Cl ₂ salt and the amounts of KCl and KOH calculated by the method disclosed in US Pat. No. 4,568,656.

Next, 10 parts of Pt / KL zeolite were added in the reactor.
% Dry O _{2 with} a gas flow of 500 ml / min at atmospheric pressure 3
Calcination at 50 ° C for 2 hours, then add 3% water to the gas stream,
The treatment was continued for another 2 hours. The catalyst is then heated at 350 ° C. with a gas flow of 10% H ₂ and 3% H ₂ O at a flow rate of 500 ml / min.
Reduction for 3 hours. The resulting new catalyst is designated as Catalyst A.

The deactivation resulting from the coke burn-off in the first stage of catalyst regeneration was carried out by using a sample of 2 g of catalyst A in the reactor.
Simulated by treatment with% O ₂ and 3% H ₂ O at a flow rate of 500 ml / min and atmospheric pressure at 510 ° C. for 2 hours.
The deactivated catalyst was then oxychlorinated using conventional conditions. Therefore, the catalyst is 0.35% HCl, 10% O ₂ and 3%.
Treated with H ₂ O at a flow rate of 500 ml / min at 510 ° C. for 5 hours. Stop HCl flow and stir the catalyst with 10% O ₂ and 3% water.
Stabilized by time treatment. After this, the catalyst 10
% H ₂ and 3% H ₂ O at a flow rate of 500 ml / min for reduction at 510 ° C. for 2 hours. The resulting comparative catalyst is designated as Catalyst B.

Further deactivation and reactivation of a sample of 2 g of Catalyst A was repeated as for Catalyst B, but during the deactivation phase CO ₂ was introduced into the reactor and the CO ₂ stream was oxychlorinated. Continued during the phase and the next oxygen stabilization phase, after which it was stopped. CO ₂ was supplied into the reactor together with other gases, and the concentration of CO ₂ was maintained at 4% (4 kPa partial pressure). Further, the oxychlorination time was 2.5 hours, and the subsequent stabilization and reduction were carried out at 350 ° C. CO ₂ was purged from the reactor with a stream of inert gas before the reduction step. The resulting catalyst is designated as Catalyst C.

The performance of catalysts A, B and C were evaluated by measuring the yield of benzene resulting from the reforming operation on 3-methylpentane, respectively. Reforming is H ₂ / 3-methylpentane ratio 6, space velocity 20 w / w / hour, temperature 510
C. and pressure of 105 psig. The results are shown in Table 1.

Table 1 Benzene yield wt% On-oil On-oil catalyst 5 hours later 10 hours A (new) 19.6 15.2 B (comparative) 18.1 12.6 C (CO ₂ present) 22. 9 17.8

The result is that when the catalyst is regenerated under normal conditions, as in catalyst B, the activity of the catalyst for the formation of aromatics is lower than that of the fresh catalyst (catalyst A), especially after a large amount of time. Indicates that. However, treating the catalyst with CO ₂ during the oxychlorination step, as in catalyst C, greatly improves the activity of the catalyst, in this case even surpassing the fresh, untreated catalyst.

Example 2 A sample of Pt / KL zeolite catalyst was removed from the reforming reactor. The catalyst contained 0.64% platinum on KL zeolite extrudate and platinum was loaded onto the zeolite at a pH of 11-12. The catalyst was on-oil (ie used to convert naphtha in the reforming process) for over 1000 hours and was regenerated three times in situ using conventional regeneration methods. This catalyst used is designated as catalyst D.

A sample of 2 g of catalyst D was regenerated at the same time as described for catalyst B in Example 1, but the oxychlorination time was 2.5 hours. The resulting comparative catalyst is Catalyst E
Indicated as.

A sample of 2 g of another catalyst D was used as catalyst C of Example 1.
Was regenerated as described for B, but the CO ₂ flow was stopped when the HCl flow was stopped and the oxygen stabilization and hydrogen reduction steps were carried out at 510 ° C. in the absence of CO ₂ . The resulting catalyst is designated as Catalyst F.

Catalysts D, E, F and new commercial catalysts (Catalyst D ¹
As shown in Example 1) was evaluated in the 3-methylpentane modification procedure as described in Example 1. The results are shown in Table 2.

Table 2 Benzene Yield% by weight On oil On oil catalyst 5 hours later 10 hours D (use) 13.7 10.0 E (comparison) 20.2 15.8 F (CO ₂ present) 23. 0 17.0 D ¹ (new) 22.1 18.9

The results show that catalyst D used is significantly deactivated compared to fresh catalyst D ¹ . The catalyst regenerated under normal conditions (Comparative Catalyst E) was reactivated to some extent, but a substantial improvement was obtained when the catalyst was reactivated in the presence of CO ₂ .

Example 3 A Pt / KL zeolite catalyst was prepared as described in Example 1, but platinum was added to the zeolite extrudate at a pH of 8.75.
Loaded with. This catalyst is designated as Catalyst G.

A sample of catalyst G was deactivated and then reactivated as for catalyst B in Example 1, but the gas stream during the deactivation stage also gave 10% CO ₂ (10 kPa partial pressure). Contained. CO ₂ was purged from the reactor before the oxychlorination step. This catalyst is designated as catalyst H.

Another sample of Catalyst G was deactivated as for Catalyst F in Example 2 and then reactivated. This catalyst is designated as catalyst I.

The performance of catalysts G, H and I was evaluated in the 3-methylpentane reforming operation as described in Example 1 and the results are shown in Table 3.

Table 3 Benzene yield wt% On-oil On-oil catalyst 5 hours later 10 hours later G (new) 14.2 9.6 H (comparative) 14.8 10.4 I (CO ₂ present) 20. 0 15.4

The results show a very substantial improvement in catalyst performance when CO ₂ is present during the oxychlorination step, but when CO ₂ is present only during the deactivation (equivalent to coke burn-off) step. Indicates otherwise.

Example 4 A Pt / KL zeolite catalyst was prepared as described in Example 1, but platinum was added to the zeolite extrudate at a pH of 10.3.
Loaded with. This catalyst is designated as Catalyst J.

Catalyst J2g was deactivated as in Catalyst B in Example 1 and then reactivated. This catalyst is designated as catalyst K.

Another sample of Catalyst J was deactivated as for Catalyst F in Example 2 and then reactivated. This catalyst is designated as catalyst L.

The performance of catalysts J, K and L was evaluated in a 3-methylpentane reforming operation as described in Example 1 and the results are shown in Table 4.

Table 4 Benzene yield% by weight On oil On oil catalyst 5 hours later 10 hours J (new) 20.2 17.7 K (comparative) 21.8 16.6 L (CO ₂ present) 25. 3 21.5

The results again show a very substantial improvement in catalytic performance when CO ₂ is present during the oxychlorination step. Furthermore, transmission electron microscopy (TEM) showed that both catalysts K and L contained highly dispersed Pt clusters with a size of 6-10Å. However, there was a clear difference between these two catalysts. Platinum was detected on the Al ₂ O ₃ binder of catalyst K, but was not present on the Al ₂ O ₃ binder of catalyst L. This is due to the presence of CO ₂ during the oxychlorination stage.
l ₂ O ₃ bonding agent and reduce the interaction between the platinum chloride species suggests that redispersion of Pt is minimized with respect to Al ₂ O ₃ bonding agent between the result oxychlorination.

Example 5 Example 2 A sample of fresh commercial catalyst (Catalyst D ¹ ) was deactivated as for Catalyst F in Example 2 and then reactivated.
I.e. contains between CO ₂ deactivation and oxychlorination step. This catalyst is designated as catalyst M.

Another sample of catalyst D ¹ was deactivated as for catalyst M and then reactivated, but with 10% CO ₂
(10 kPa partial pressure) was also included during the reduction stage. This catalyst is designated as catalyst N.

Another sample of catalyst D ¹ was used as catalyst B in Example 2.
As above, ie, deactivated and reactivated under normal conditions, but 10% CO ₂ (10 kPa partial pressure) was present during the reduction step. This catalyst is designated as catalyst O.

Another sample of catalyst D ¹ was deactivated and reactivated as for catalyst O, but the stabilization and reduction steps were each performed at 350 ° C. This catalyst is designated as catalyst P.

Finally, catalyst D ¹ was reduced with 10% H ₂ , 3% H ₂ O and 4% CO ₂ (4 kPa partial pressure) at a temperature of 510 ° C. for 2 hours. This catalyst is designated as Catalyst Q.

The performance of the above catalyst was evaluated in the 3-methylpentane reforming operation as described in Example 1 and the results are shown in Table 5.
Shown inside.

Table 5 Benzene Yield% by weight On oil On oil catalyst 5 hours later 10 hours M 22.7 18.7 N 2.5 2.0 O 0.9-P 2.6 2.0 Q 0 .9 - D ¹ 22.1 18.9

The results show that when CO ₂ is present during the reduction stage and the reduction temperature is between 350 and 510 ° C., there is a substantial reduction in catalyst performance regardless of the conditions of the previous regeneration stage. Catalyst N
And O TEM studies showed the presence of platinum agglomerates of size 10-30Å.

Example 6 3 g of the new catalyst D ^{1 of} Example 2 was added to 10 vol% O _{2 in} helium.
Medium was heated to 510 ° C. at a flow rate of 500 ml / min. After the catalyst reached 510 ° C, CO ₂ was added to the gas stream to reach 1% by volume.
CO ₂ (1 kPa partial pressure) was applied and oxygen was stopped after 5 minutes. Residual oxygen was purged out of the reactor with 1 vol% CO ₂ in helium at 500 ml / min for 10 minutes. Hydrogen was then added to give 10 vol% H ₂ and the total flow was kept at 500 ml / min. This treatment was continued for 1.5 hours. This catalyst is designated as catalyst R.

Another 2 g of the catalyst D ^{1 from} Example 2 was added to 400% at a flow rate of 500 ml / min in 10 vol% CO ₂ in helium.
Heated to ° C. After the catalyst reached 400 ° C., CO ₂ and water were added to the gas stream to obtain 0.2 vol% CO ₂ (0.2 kP
a partial pressure) and 3% by volume of water. Then the temperature is changed to 510
Raised to ℃. The catalyst was treated under the above gas mixture for 35 minutes and then oxygen was turned off. Residual oxygen was purged out of the reactor for 10 minutes and then hydrogen was added to give 10% by volume hydrogen. The reduction was carried out for 1.5 hours. This catalyst is designated as catalyst S.

Another 3 g of the catalyst D ¹ of Example 2 was added first to 5
Reduction with 10 vol% hydrogen in helium at 10 ° C. at a flow rate of 500 ml / min for 1 hour. Then CO ₂ was added to give 0.05% by volume (0.05 kPa partial pressure) and the treatment was continued for 1.5 hours. This catalyst is designated as catalyst T.

Another 2 g of catalyst D ¹ of Example 2 was treated in the same manner as catalyst T, but CO ₂ was 0.025% by volume (0.025 kPa partial pressure) in the H ₂ and CO ₂ stages, The flow rate was 1000 ml / min. This catalyst is designated as catalyst U.

The performance of catalysts R, S, T and U was evaluated in a 3-methylpentane reforming operation as described in Example 1 and the results are shown in Table 6.

Table 6 Benzene yield% by weight CO ₂ on oil in hydrogen On oil catalyst capacity% 5 hours later 10 hours later D ¹ (new) 0 22.1 18.9 R 1 5.8 4.7 S 0.2 10.4 9.15 T 0.05 18 16.1 U 0.025 20 18.1

The results again show that CO ₂ is detrimental to the catalyst when it is present during the reduction stage of Pt / KL zeolite catalysts. TEM study of catalyst S shows that platinum particles are 10-25Å
It showed that the cluster size was about 1. 0.025
There was still a slight loss of activity at volume% (0.025 kPa partial pressure), but this level of decline is more acceptable. The above results also show that exposure of the pre-reduced catalyst to CO ₂ containing hydrogen also results in catalyst deactivation (catalysts T and U). Therefore, catalyst regeneration after CO ₂ should be purged to a low level before the hydrogen reduction. Exclusion of CO _{2 from} the process gas is also important in the activation of new catalysts.

2 g of the new catalyst D ^{1 from} Example 2 was heated to 200 ° C. in helium at a flow rate of 500 ml / min. The catalyst was dried under these conditions for 1 hour. The temperature of the catalyst was then raised to 350 ° C. Hydrogen was added to give 10% by volume. The catalyst was reduced for 1.5 hours. CO was then added to the gas mixture to 0. 5% CO by volume (0.5 kPa partial pressure) was applied.
This treatment was continued for 1.5 hours. The CO was turned off and stripped from the catalyst with 10 vol% hydrogen for 1.5 hours at 350 ° C. This catalyst is designated as Catalyst V.

Another 2 g of catalyst D ₁ of Example 2 was treated as for catalyst V, but with a CO concentration of 0.1% by volume (0.
1 kPa partial pressure) and the gas flow rate in the H ₂ and CO stages is
It was 1000 ml / min. This catalyst is designated as catalyst W. Another 2 g of catalyst D ¹ of Example 2 was added to 10 g in helium.
Heat to 400 ° C. in a volume% O ₂ at a flow rate of 500 ml / min. After 1 hour at 400 ° C, the temperature of the catalyst was raised to 510 ° C. After purging oxygen for 10 minutes, CO was added and 0.1 vol% (0.2 kPa partial pressure) was added. Then add hydrogen 1
0% by volume was given. This treatment was continued for 1.5 hours. This catalyst is designated as catalyst X.

The performance of catalysts V, W and X was evaluated in the 3-methylpentane reforming operation as described in Example 1 and the results are shown in Table 7.

Table 7 Benzene yield% by weight CO on oil in H ₂ On oil catalyst capacity% (temperature) 5 hours later 10 hours later D ¹ (new) 0 22.1 18.9 V 0.5 (350 ° C) 15 13.3 W 0.1 (350 ° C) 16.9 15.2 X 0.1 (510 ° C) 12.6 10

The results show that the CO present during the hydrogen reduction step deactivates the catalyst in the temperature range 350-510 ° C. The catalyst is more deactivated when the H ₂ and CO treatments are at higher temperatures (comparison of catalysts X and W). The reducing catalyst is also deactivated when exposed to H ₂ and CO (catalysts V and W). TEM studies of Catalyst X show that platinum particles have agglomerated and particle sizes up to 40Å have been observed. Therefore, CO should be purged to a low level in the reduction of the new catalyst and the gas stream should
There must be no.

Example 8 3 g of catalyst D ^{1 of} Example 2 were heated to 200 ° C. in helium at a flow rate of 500 ml / min. The catalyst was dried under these conditions for 1 hour. Oxygen was added to give 10% by volume and the temperature of the catalyst was raised to 510 ° C. The oxygen was then turned off and helium was purged out of the reactor for 10 minutes. CO ₂ was added to the gas stream to give 1 vol% CO ₂ (1 kPa partial pressure). This treatment was continued for 1.5 hours. This catalyst is designated as Catalyst V.

2 g of the catalyst D ^{1 of} Example 2 was added to ¹ g in helium.
Heat to 350 ° C. in 0 vol% O ₂ at a flow rate of 500 ml / min. The catalyst was treated under these conditions for 20 minutes. The oxygen was then stopped and purged out of the reactor with helium for 30 minutes. CO ₂ was added to the gas stream to give 1% by volume (1 kPa partial pressure). This treatment was continued for 1.5 hours. This catalyst is catalyst Z
Indicated as.

2 g of catalyst D ^{1 from} example 2 were heated to 200 ° C. in helium at a flow rate of 500 ml / min. The catalyst was dried under these conditions for 1 hour. Hydrogen was added to the gas stream to give 10 vol% H ₂ . The reduction was carried out for 1.5 hours. The hydrogen was then turned off and purged with helium out of the reactor for 1 hour. CO
Is added to the gas flow to add 0.5% by volume CO (0.5 kPa partial pressure)
Was given. This treatment was continued for 1.5 hours. This catalyst is designated as catalyst AA.

2 g of catalyst D ^{1 in} Example 2 were treated like catalyst AA, but with a CO concentration of 0.1% by volume (0.1% by volume).
The flow rate was 1000 ml / min (kPa partial pressure). This catalyst is designated as catalyst BB.

The performance of catalysts Z, AA and BB was evaluated in the 3-methylpentane reforming operation as described in Example 1 and the results are shown in Table 8.

Table 8 Benzene yield% by weight CO _x on oil in He On oil catalyst capacity% (temperature) 5 hours later 10 hours later D ¹ (new) 0 22.1 18.9 Y 1 (510 ° C.) 13.5 11.9 Z 0 (350 ° C) 21.8 19 AA 0.5 (350 ° C) 16.4 14.3 BB 0.1 (350 ° C) 17.5 15.2

The results show that exposure of the catalyst to hydrogen-free CO _{2 at} low temperature (350 ° C.) does not result in catalyst deactivation (catalyst Z). However, when the exposure temperature is raised to 510 ° C., significant catalyst deactivation occurs (catalyst Y). In contrast, the reduced catalyst was CO-free at low temperature (350 ° C) in the absence of hydrogen.
When exposed to, the catalyst is deactivated.

Example 9 5 g of 4 g reforming catalyst (catalyst CC) obtained from Ketjen containing 0.6% by weight Pt in 1/16 ″ Al ₂ O ₃ extrudate.
51 under 20 vol% O ₂ in helium at 00 ml / min
Heated to 0 ° C. The catalyst was treated under these conditions for 1 hour.
Oxygen was purged from the reactor with helium for 10 minutes.
CO and H ₂ were added to the gas stream and 4 vol% CO (4 kPa partial pressure) and 20 vol% H ₂ were added. This treatment was continued for 2 hours. This catalyst is designated as catalyst DD.

The new catalyst CC and the "used" catalyst DD were evaluated by hydrogen chemisorption to determine the dispersion of Pt particles. This 2
The two catalysts were first reduced for 2 hours at 475 ° C. in 100% by volume hydrogen at a flow rate of 1000 ml / min. They were then evacuated at 450 ° C for 1 hour. Hydrogen chemisorption was performed at 35 ° C. The detailed operation and equipment used for hydrogen chemisorption are described by Toaster et al. (SJ Tauster, SC Fung and RL
Garten) J. Am. Chem. Soc., 100 , 170.
(1978). This technology is catalyst 1
Gives a measure for the volume of hydrogen irreversibly adsorbed by g. From this, the atomic ratio H between hydrogen atoms and metal atoms H
/ Pt can be calculated. The results are shown in Table 9.

[0093]

The results show that exposure of the catalyst to CO in the reduction stage also deactivates the Pt / Al ₂ O ₃ catalyst. Low H / Pt ratio means that few Pt atoms are surface atoms, and
It suggests that the Pt clusters increased in size.

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[Procedure amendment]

[Submission date] March 15, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

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[Claims]

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[Document name to be amended] Statement

[Correction target item name] 0001

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[0001]

BACKGROUND OF THE INVENTION A. FIELD OF THE INVENTION The present invention relates to a method for regenerating and reactivating coke fouling deactivated catalysts containing one or more Group VIII noble metals, refractory supports and binders. The invention is also at least one
Activates new catalyst containing Group VIII noble metal, carrier and binder
It also relates to the method of sexualizing. These catalysts are commonly used in hydrocarbon conversion processes, especially in catalytic reforming.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

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We have found that the presence of carbon dioxide during the redispersion stage of the catalyst regeneration and reactivation process is active, and therefore the performance of the catalyst,
Admitted to raise. The catalysts which have been subjected to the process according to the invention show a high selectivity towards the formation of the desired aromatic compounds in the naphtha reforming process and also a high lifetime.
That is, it maintains a sufficient activation level for a longer period of time than the catalyst regenerated by a conventional method. The process according to the invention has the particular advantage for the regeneration of Group VIII-containing catalysts supported by zeolitic materials.

[Procedure amendment 4]

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The source of carbon dioxide can be, for example, pure carbon dioxide gas or a mixture of carbon dioxide and an inert gas fed directly into the reactor in which the catalyst is regenerated. The carbon dioxide source can also be mixed with other gases used during the oxychlorination step, typically halogen gas, oxygen and optional steam. Alternatively, the source of carbon dioxide can be a compound that liberates carbon dioxide, which can be a gas, a liquid or a solid, but is preferably a gas to facilitate its introduction into the reactor. ..

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We have also found that the presence of carbon dioxide or carbon monoxide during the reduction step can adversely affect the performance of the resulting catalyst. Therefore, the reduction is preferably carried out in the presence of minimal, if any, carbon dioxide and carbon monoxide. The amount of carbon dioxide and carbon monoxide present during the hydrogen reduction step should not exceed 0.05 kPa partial pressure. It is particularly preferred to eliminate carbon dioxide and carbon monoxide prior to the reduction step when the catalyst support is L zeolite. After the oxychlorination step, if the system is flushed with oxygen as described above, this will result in the removal of carbon containing gas. However, it is also preferable to remove the residual oxygen before introducing the hydrogen gas. Therefore, it is preferable to purge the system with an inert gas such as nitrogen or helium before the start of the reduction step, whether or not oxygen treatment is performed.

[Procedure correction 6]

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[Correction target item name] 0035

[Correction method] Change

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The reduction of the catalyst prior to its use in the reforming step involves the reduction of carbon dioxide and carbon monoxide from 0 to 0, whether or not it has been activated or reactivated in the presence of carbon dioxide.
It has also been found to work favorably in the presence of a partial pressure of 0.05 kPa. More preferably the reduction is carried out in the substantial absence of these carbon containing gases. The presence of high levels of these gases significantly reduces the activity of the catalyst during reforming. This applies to the reduction of both fresh and regenerated catalysts.

[Procedure Amendment 7]

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[Correction target item name] 0036

[Correction method] Change

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Once the catalyst has been reduced, it is advantageous not to expose the catalyst to carbon dioxide and carbon monoxide in an amount above a partial pressure of 0.05 kPa before it is used in the reforming process.

[Procedure Amendment 8]

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[0079] The fresh catalyst ^D 1 2 g Example 7 Example 2 was heated to 200 ° C. in helium at 500 ml / min flow rate. The catalyst was dried under these conditions for 1 hour. The temperature of the catalyst is then 350 ° C
I raised it to. Hydrogen was added to give 10% by volume. The catalyst was reduced for 1.5 hours. CO was then added to the gas mixture to give 0.5 vol% CO (0.5 kPa partial pressure). This treatment was continued for 1.5 hours. The CO was stopped and stripped from the catalyst with 10 vol% hydrogen for 1.5 hours at 350 ° C.
This catalyst is designated as Catalyst V.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0084

[Correction method] Change

[Correction content]

Example 8 3 g of catalyst D ^{1 from} example 2 were heated to 200 ° C. in helium at a flow rate of 500 ml / min. The catalyst was dried under these conditions for 1 hour. Oxygen was added to give 10% by volume and the temperature of the catalyst was raised to 510 ° C. The oxygen was then turned off and helium was purged out of the reactor for 10 minutes. CO in gas flow
₂ was added to give 1 vol% CO ₂ (1 kPa partial pressure).
This treatment was continued for 1.5 hours. This catalyst is designated as catalyst Y.

Claims (10)

[Claims] 1. A method of regenerating and reactivating coke fouling, deactivated catalyst comprising at least one Group VIII noble metal, carrier and binder, comprising: (a) substantially all coke from the catalyst. Remove and (b) redisperse the noble metal (s) on the carrier, the redispersion bringing the catalyst into contact with the halogen or halide-containing gas and the oxygen source present (oxychlorination), and carbon dioxide. The amount of carbon dioxide is substantially at least 2 kPa in the reaction vessel during the period in which the catalyst is contacted with the halogen or halide containing gas.
And (c) the catalyst is stabilized by treatment with an inert or oxygen-containing gas, and (d) carbon dioxide and carbon monoxide are removed from the reaction vessel during the reduction step (e). Substantially removing so that the amount of carbon monoxide is at a partial pressure of less than 0.025 kPa, and (e) chemically reducing the catalyst. 2. A process according to claim 1, wherein the amount of carbon dioxide present during step (b) is maintained in the reaction vessel at a partial pressure of 2-35 kPa. 3. The contact between the catalyst and carbon dioxide gas is started at substantially the same time as the start of the contact between the catalyst and the halogen gas, and the contact is ended at substantially the same time as the end of the contact between the catalyst and the halogen gas. The method of claim 1. 4. The method of claim 1, wherein the contact between the catalyst and carbon dioxide is maintained during the stabilization process and then terminated. 5. The method according to claim 1, wherein the reaction vessel is purged with an inert gas before the reduction step (e). 6. The reaction vessel is subjected to a pressure-decompression cycle with an inert gas before the reduction step (e) until the concentration of carbon dioxide and carbon monoxide gas is diluted to less than 0.025 kPa. The method described in. 7. A method of regenerating and reactivating a coke contaminated catalyst comprising at least one Group VIII noble metal, a KL zeolite support and a binder, comprising: (a) removing substantially all coke from the catalyst. And (b) redispersing the noble metal (s) on the support, and (c) chemically reducing the catalyst,
A method wherein the reduction step (c) is carried out in the reaction vessel in the presence of a partial pressure of carbon dioxide and carbon monoxide gas between 0 and less than 0.025 kPa. 8. A method for activating a new catalyst comprising at least one Group VIII noble metal, a carrier and a binder, comprising: (a) the catalyst being halogen or halide in the presence of carbon dioxide in a reaction vessel. Treating with a gas containing, and (b) chemically reducing the catalyst. 9. A method of treating a new catalyst comprising at least one Group VIII noble metal, a KL zeolite support and a binder, wherein carbon dioxide and carbon monoxide gas with a partial pressure between 0 and less than 0.025 kPa. A method comprising a chemical reduction step carried out in the presence of 10. The method according to claim 1, wherein the catalyst is stabilized by treatment with an oxygen-containing gas.