CA1055921A - Reactivation of particulate catalyst masses - Google Patents
Reactivation of particulate catalyst massesInfo
- Publication number
- CA1055921A CA1055921A CA227,826A CA227826A CA1055921A CA 1055921 A CA1055921 A CA 1055921A CA 227826 A CA227826 A CA 227826A CA 1055921 A CA1055921 A CA 1055921A
- Authority
- CA
- Canada
- Prior art keywords
- catalyst
- liquid
- reactivating
- bed
- hydrocarbons
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/28—Regeneration or reactivation
- B01J27/285—Regeneration or reactivation of catalysts comprising compounds of phosphorus
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Catalysts (AREA)
- Polymerization Catalysts (AREA)
Abstract
ABSTRACT
A method for the restoration of porosity and catalytic activity to a catalyst bed composed of a mass of solid particles, where the catalyst bed has been deactivated and occluded by the deposition of carbonized and polymerized hydrocarbons. The catalyst is repeatedly washed, at superatmospheric conditions of temperature and pressure, with a liquid phase hydrocarbon mixture containing aromatic hydrocarbon species.
Deactivating materials are dissoved within the hydrocarbon mixture and are removed from the catalyst bed when washing mixture is withdrawn.
A method for the restoration of porosity and catalytic activity to a catalyst bed composed of a mass of solid particles, where the catalyst bed has been deactivated and occluded by the deposition of carbonized and polymerized hydrocarbons. The catalyst is repeatedly washed, at superatmospheric conditions of temperature and pressure, with a liquid phase hydrocarbon mixture containing aromatic hydrocarbon species.
Deactivating materials are dissoved within the hydrocarbon mixture and are removed from the catalyst bed when washing mixture is withdrawn.
Description
ïS921 Solid particulate catalysts disposed in beds with-in reaction zones have found varied utility in many commercial ` industries such as the pharmaceutical, detergent, insecticidal, and heavy chemical. These catalysts are generally employed for the treatment of various hydrocarbon mixtures and fractions.
Catalyst deactivation is a problem. Catalyst de-activation may result from a combination of adverse effects, one of which is the mechanical covering of catalytically ac-tive centers and surfaces by materials which shield the ac-- 10 tive centers from the hydrocarbons being processed.
Commercial processes abound which involve contact-ing fluid hydrocarbon and other materials with a bed of solid catalyst particulates for the purpose of physical or chemical treatment of the fluid materials. In many of these processes, both vapor and liquid reactants are present.
The mixed-phase contacting with catalyst allows heavier components to contact the catalyst for long periods of time. This is because the heavier components exist in the liquid phase, and the liquid droplets passing through a particulate bed tend to coalesce and adhere to the surfaces of the catalyst particles. Long residence times promote for-mation of high molecular weight, tar-like polymers and carbon-ization of hydrocarbons. Some of the polymers and carbon-ized hydrocarbons adhere to the surfaces of the catalyst parti-cles, and physically cover the catalytically acitve sites.Catalytic activity then declines.
The accumulation of polymers and carbonized hydro-carbons, or coke, also tends to plug the catalyst bed.
1~)559Zl The result is a continual increase in pressure drop across the catalyst bed which eventually reduces plant capacity or requires a shutdown.
A known method for reactivating a catalyst is to burn carbon from the catalyst. However, in certain processes, namely the phosphoric acid catalyzed polymerization of hydro-carbons, such burning could destroy the catalyst. In other processes, such as hydrotreating of hydrocarbons, the high quantity of carbon present on the catalyst often makes burn-ing hazardous or inconveniently lengthy. For these reasons it has been the custom in the art to discard deactivated poly-merization and hydrotreating catalyst and replace them with new catalysts, a costly and wasteful practice.
Researchers in these arts have tried for years to find a better way to regenerate these catalysts.
A method has now been found which permits these catalysts to be regenerated without burning.
Accordingly, the present invention provides a method for the in situ reactivation of a bed of catalyst com-prising solid phosphoric acid catalyst which comprises the steps of: (a) inundating said catalyst at à temperature of 40 to 370C and pressure of 1 1/3 to 100 atmospheres, absolute, in a reactivating liquid of a mixture of hydrocarbons which is sub-stantially free from sulfur, which contains at least 5 weight percent aromatics and which boils within the range of 40 to 230C;
(b) withdrawing said reactivating liquid from said catalyst;
and (c) repeating steps (a) and (b), above, at least one time.
105~9'~
The present invention involves a method for the reactivation of a particulated solid catalyst disposed in a catalyst bed which has been deactivated by the deposition upon the catalyst particles of polymerized and carbonized hydrocarbonaceous materials.
The deactivated catalyst is repeatedly inundated with a reactivating liquid at a predetermined temperature and pressure. The reactivating liquid is an aromatic-con-taining, hydrocarbon mixture. After each inundation, the reactivating liquid, including polymers and carbonized hydrocarbons which have dissolved therein, is withdrawn from the catalyst particles. Removal of the deactivating materials restores catalyst bed activity and porosity.
The polymerization catalyst to which this inven-tion pertains is that commonly referred to as SPA (solidphosphoric acid) catalyst. SPA contains, as its principal ingredients, a phosphoric acid and a natural porous silica material. The latter is commonly referred to as kieselguhr or diatomaceous earth. The mixture of phosphoric acid and silicious material is normally calcined and then formed into small particles for use as a catalyst mass in the re-action zone of a polymerization process unit.
The method of the present invention permits re-activating of catalyst without removal of the catalyst from its associated reaction zone. The method consists of liquid phase dissolution of catalyst deactivating materials with a reactivating liquid. Aromatic hydrocarbons have a high 9Zl solubility for the particular types of polymerized and carbonized hydrocarbons which contaminate the aforementioned catalysts. The present invention involves introduction of a suitable reactivating liquid into the deactivated catalyst bed at certain conditions of temperature and pressure. The liquid must inundate the entire bed. Solution of at least a portion of the contaminants into the washing liquid then occurs. The reactivating liquid and dissolved contaminants are then withdrawn from the catalyst bed. These steps are repeated as desired to attain the required degree of contami-nate removal.
Washing liquids suitable for use are hydrocarbon mixtures which boil within the range of about 40 to 250C.
These mixtures must contain at least 5 wt ~, and preferably 15 to 85 wt % aromatic hydrocarbons. Preferred reactivat-ing liquids include nydrodesulfurized naphthas, catalytic reformates and blends of substantially sulfur-free aromatic and aliphatic compounds.
The method of this invention requires for maximum efficacy that the reactivation temperature and pressure be within certain limits. The temperature of the catalyst bed and reactivating liquid during reactivation should be about 40 to 370c, preferably about 90 to 260C. The pressure should be about 1 1/3 to 100 atmospheres, absolute, preferably about 8 to 20 atmospheres. The method of the present invention is particularly useful for in situ reactivation of catalysts because the normal operating conditions within the reaction ~05~9Zl zones of the aforementioned processes are approximately with-in the operating conditions at which the present method is most effective. Thus regeneration can occur during a mom-entary cessation of normal operation without drastic adjust-ment of conditions. The temperature and pressure actuallyused depend to a certain extent upon the volatility of the washing liquid being used. If a volatile liquid is used it may be necessary to reduce the temperature or increase the pressure of the reaction zone before reactivation begins to assure that the washing liquid will not be substantilly vaporized upon entry into the reaction zone. It is prefer-able that the washing liquid be introduced into the bottom of the catalyst bed, inundating it in upflow.
The number of times the washing action is repeat-ed should be at least one and less than ten. The preferrednumber of washes is three. Three washes are sufficient to adequately remove the polymers and carbonized hydrocarbons without dehydrating the SPA catalyst to any significant de-gree. As is well known by those skilled in the art the SPA
catalyst depends for optimum activity upon a certain level of hydration.
In a polymerization unit using SPA catalyst, to pro-duce motor fuel from light olefinic gases, high reaction zone pressure drop was noted. The reaction zone pressure drop was 5 atm instead of the 0.34 atm pressure drop encountered with new catalyst. Plant production was reduced due to the pressure drop of the reaction zone. The catalyst mass was reactivated in the following manner. The polymerization unit operation ~OSS921 was stopped. The reaction zone was allowed to remain hot.
The reaction zone was depressurized to 15 atm, absolute and catalytic reformate at 90C introduced into the bottom of the reaction zone, completely inundating the catalyst mass.
The reformate was immediately drained from the reaction zone and discarded. The reformate introduction and draining were repeated twice for a total of three inundations. The poly-merization unit was returned to normal operation. Pressure drop in the reaction zone was reduced to 0.34 atm, and catalyst activity was also restored to essentially that of fresh catalyst.
This invention is not limited in its application to SPA operations which produce motor fuel.
A further advantage of the present invention relates to the avoidance of pollution. SPA catalyst is commonly used for only one operational run. When the catalyst became in-active or the reaction zone pressure drop became excessive,the catalyst is commonly discarded. Because SPA catalyst con-tains phosphoric acid, it is not a good landfill. By the use of the present invention the catalyst can be reactivated and reused many times, greatly reducing the amount of SPA catalyst to be discarded.
Catalyst deactivation is a problem. Catalyst de-activation may result from a combination of adverse effects, one of which is the mechanical covering of catalytically ac-tive centers and surfaces by materials which shield the ac-- 10 tive centers from the hydrocarbons being processed.
Commercial processes abound which involve contact-ing fluid hydrocarbon and other materials with a bed of solid catalyst particulates for the purpose of physical or chemical treatment of the fluid materials. In many of these processes, both vapor and liquid reactants are present.
The mixed-phase contacting with catalyst allows heavier components to contact the catalyst for long periods of time. This is because the heavier components exist in the liquid phase, and the liquid droplets passing through a particulate bed tend to coalesce and adhere to the surfaces of the catalyst particles. Long residence times promote for-mation of high molecular weight, tar-like polymers and carbon-ization of hydrocarbons. Some of the polymers and carbon-ized hydrocarbons adhere to the surfaces of the catalyst parti-cles, and physically cover the catalytically acitve sites.Catalytic activity then declines.
The accumulation of polymers and carbonized hydro-carbons, or coke, also tends to plug the catalyst bed.
1~)559Zl The result is a continual increase in pressure drop across the catalyst bed which eventually reduces plant capacity or requires a shutdown.
A known method for reactivating a catalyst is to burn carbon from the catalyst. However, in certain processes, namely the phosphoric acid catalyzed polymerization of hydro-carbons, such burning could destroy the catalyst. In other processes, such as hydrotreating of hydrocarbons, the high quantity of carbon present on the catalyst often makes burn-ing hazardous or inconveniently lengthy. For these reasons it has been the custom in the art to discard deactivated poly-merization and hydrotreating catalyst and replace them with new catalysts, a costly and wasteful practice.
Researchers in these arts have tried for years to find a better way to regenerate these catalysts.
A method has now been found which permits these catalysts to be regenerated without burning.
Accordingly, the present invention provides a method for the in situ reactivation of a bed of catalyst com-prising solid phosphoric acid catalyst which comprises the steps of: (a) inundating said catalyst at à temperature of 40 to 370C and pressure of 1 1/3 to 100 atmospheres, absolute, in a reactivating liquid of a mixture of hydrocarbons which is sub-stantially free from sulfur, which contains at least 5 weight percent aromatics and which boils within the range of 40 to 230C;
(b) withdrawing said reactivating liquid from said catalyst;
and (c) repeating steps (a) and (b), above, at least one time.
105~9'~
The present invention involves a method for the reactivation of a particulated solid catalyst disposed in a catalyst bed which has been deactivated by the deposition upon the catalyst particles of polymerized and carbonized hydrocarbonaceous materials.
The deactivated catalyst is repeatedly inundated with a reactivating liquid at a predetermined temperature and pressure. The reactivating liquid is an aromatic-con-taining, hydrocarbon mixture. After each inundation, the reactivating liquid, including polymers and carbonized hydrocarbons which have dissolved therein, is withdrawn from the catalyst particles. Removal of the deactivating materials restores catalyst bed activity and porosity.
The polymerization catalyst to which this inven-tion pertains is that commonly referred to as SPA (solidphosphoric acid) catalyst. SPA contains, as its principal ingredients, a phosphoric acid and a natural porous silica material. The latter is commonly referred to as kieselguhr or diatomaceous earth. The mixture of phosphoric acid and silicious material is normally calcined and then formed into small particles for use as a catalyst mass in the re-action zone of a polymerization process unit.
The method of the present invention permits re-activating of catalyst without removal of the catalyst from its associated reaction zone. The method consists of liquid phase dissolution of catalyst deactivating materials with a reactivating liquid. Aromatic hydrocarbons have a high 9Zl solubility for the particular types of polymerized and carbonized hydrocarbons which contaminate the aforementioned catalysts. The present invention involves introduction of a suitable reactivating liquid into the deactivated catalyst bed at certain conditions of temperature and pressure. The liquid must inundate the entire bed. Solution of at least a portion of the contaminants into the washing liquid then occurs. The reactivating liquid and dissolved contaminants are then withdrawn from the catalyst bed. These steps are repeated as desired to attain the required degree of contami-nate removal.
Washing liquids suitable for use are hydrocarbon mixtures which boil within the range of about 40 to 250C.
These mixtures must contain at least 5 wt ~, and preferably 15 to 85 wt % aromatic hydrocarbons. Preferred reactivat-ing liquids include nydrodesulfurized naphthas, catalytic reformates and blends of substantially sulfur-free aromatic and aliphatic compounds.
The method of this invention requires for maximum efficacy that the reactivation temperature and pressure be within certain limits. The temperature of the catalyst bed and reactivating liquid during reactivation should be about 40 to 370c, preferably about 90 to 260C. The pressure should be about 1 1/3 to 100 atmospheres, absolute, preferably about 8 to 20 atmospheres. The method of the present invention is particularly useful for in situ reactivation of catalysts because the normal operating conditions within the reaction ~05~9Zl zones of the aforementioned processes are approximately with-in the operating conditions at which the present method is most effective. Thus regeneration can occur during a mom-entary cessation of normal operation without drastic adjust-ment of conditions. The temperature and pressure actuallyused depend to a certain extent upon the volatility of the washing liquid being used. If a volatile liquid is used it may be necessary to reduce the temperature or increase the pressure of the reaction zone before reactivation begins to assure that the washing liquid will not be substantilly vaporized upon entry into the reaction zone. It is prefer-able that the washing liquid be introduced into the bottom of the catalyst bed, inundating it in upflow.
The number of times the washing action is repeat-ed should be at least one and less than ten. The preferrednumber of washes is three. Three washes are sufficient to adequately remove the polymers and carbonized hydrocarbons without dehydrating the SPA catalyst to any significant de-gree. As is well known by those skilled in the art the SPA
catalyst depends for optimum activity upon a certain level of hydration.
In a polymerization unit using SPA catalyst, to pro-duce motor fuel from light olefinic gases, high reaction zone pressure drop was noted. The reaction zone pressure drop was 5 atm instead of the 0.34 atm pressure drop encountered with new catalyst. Plant production was reduced due to the pressure drop of the reaction zone. The catalyst mass was reactivated in the following manner. The polymerization unit operation ~OSS921 was stopped. The reaction zone was allowed to remain hot.
The reaction zone was depressurized to 15 atm, absolute and catalytic reformate at 90C introduced into the bottom of the reaction zone, completely inundating the catalyst mass.
The reformate was immediately drained from the reaction zone and discarded. The reformate introduction and draining were repeated twice for a total of three inundations. The poly-merization unit was returned to normal operation. Pressure drop in the reaction zone was reduced to 0.34 atm, and catalyst activity was also restored to essentially that of fresh catalyst.
This invention is not limited in its application to SPA operations which produce motor fuel.
A further advantage of the present invention relates to the avoidance of pollution. SPA catalyst is commonly used for only one operational run. When the catalyst became in-active or the reaction zone pressure drop became excessive,the catalyst is commonly discarded. Because SPA catalyst con-tains phosphoric acid, it is not a good landfill. By the use of the present invention the catalyst can be reactivated and reused many times, greatly reducing the amount of SPA catalyst to be discarded.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for the in situ reactivation of a bed of solid phosphoric acid catalyst deactivated by the deposition of polymerized and carbonized hydrocarbonaceous materials of said catalyst and disposed within a hydrocarbon polymerization zone which comprises the steps of:
(a) inundating said catalyst at a temperature of 40 to 370°C and pressure of 1 1/3 to 100 atmospheres, absolute, in a reactivating liquid of a mixture of hydrocarbons which is sub-stantially free from sulfur, which contains at least 5 weight percent aromatics and which boils within the range of 40 to 230°C;
(b) withdrawing said reactivating liquid from said catalyst mass; and (c) repeating steps (a) and (b), above, at least one time.
(a) inundating said catalyst at a temperature of 40 to 370°C and pressure of 1 1/3 to 100 atmospheres, absolute, in a reactivating liquid of a mixture of hydrocarbons which is sub-stantially free from sulfur, which contains at least 5 weight percent aromatics and which boils within the range of 40 to 230°C;
(b) withdrawing said reactivating liquid from said catalyst mass; and (c) repeating steps (a) and (b), above, at least one time.
2. Method of claim 1 wherein the reactivating liquid is a catalytic reformate.
3. Method of claim 1 wherein the catalyst deactivating materials principally comprise polymerized and carbonized com-ponents of a hydrocarbon feed of an admixture of hydrocarbons con-taining olefins with two to fifteen carbon atoms per molecule.
4. Method of any of claims 1 to 3 wherein the reactivating liquid is introduced into the bottom of the bed of catalyst.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US47568674A | 1974-06-03 | 1974-06-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1055921A true CA1055921A (en) | 1979-06-05 |
Family
ID=23888669
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA227,826A Expired CA1055921A (en) | 1974-06-03 | 1975-05-27 | Reactivation of particulate catalyst masses |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS50153790A (en) |
| BR (1) | BR7503454A (en) |
| CA (1) | CA1055921A (en) |
| CS (1) | CS191266B2 (en) |
| DE (1) | DE2524223A1 (en) |
| ES (1) | ES438131A1 (en) |
| FR (1) | FR2272736B1 (en) |
| GB (1) | GB1500036A (en) |
| IN (1) | IN143866B (en) |
| IT (1) | IT1035834B (en) |
| ZA (1) | ZA753372B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5932778A (en) * | 1997-09-30 | 1999-08-03 | Bp Amoco Corporation | Shutdown process for olefin polymerization reactor |
| US6025534A (en) * | 1998-04-07 | 2000-02-15 | Bp Amoco Corporation | Olefin polymerization process |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5487693A (en) * | 1977-12-23 | 1979-07-12 | Nippon Petrochemicals Co Ltd | Catalyst regeneration |
| MX2014015227A (en) * | 2014-12-11 | 2016-06-10 | Inst Mexicano Del Petróleo | In-situ washing procedure to recover the catalytic activity of a deactivated hydrodesulfurization catalyst. |
| WO2019097720A1 (en) * | 2017-11-20 | 2019-05-23 | 東京電力ホールディングス株式会社 | Regenerating treatment method for catalyst and catalyst regenerating treatment device |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2382318A (en) * | 1942-04-08 | 1945-08-14 | Universal Oil Prod Co | Alkylation of benzene |
| US2658933A (en) * | 1951-08-17 | 1953-11-10 | Standard Oil Dev Co | Slurry polymerization process |
| JPS498483A (en) * | 1972-05-24 | 1974-01-25 | ||
| JPS5324917B2 (en) * | 1972-05-31 | 1978-07-24 |
-
1975
- 1975-01-17 JP JP50007661A patent/JPS50153790A/ja active Pending
- 1975-05-23 GB GB22559/75A patent/GB1500036A/en not_active Expired
- 1975-05-23 IT IT49740/75A patent/IT1035834B/en active
- 1975-05-26 FR FR7516325A patent/FR2272736B1/fr not_active Expired
- 1975-05-26 ZA ZA00753372A patent/ZA753372B/en unknown
- 1975-05-27 CA CA227,826A patent/CA1055921A/en not_active Expired
- 1975-05-28 IN IN1076/CAL/75A patent/IN143866B/en unknown
- 1975-05-29 CS CS753786A patent/CS191266B2/en unknown
- 1975-05-31 DE DE19752524223 patent/DE2524223A1/en not_active Withdrawn
- 1975-06-02 BR BR4421/75D patent/BR7503454A/en unknown
- 1975-06-02 ES ES438131A patent/ES438131A1/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5932778A (en) * | 1997-09-30 | 1999-08-03 | Bp Amoco Corporation | Shutdown process for olefin polymerization reactor |
| US6025534A (en) * | 1998-04-07 | 2000-02-15 | Bp Amoco Corporation | Olefin polymerization process |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1035834B (en) | 1979-10-20 |
| JPS50153790A (en) | 1975-12-11 |
| BR7503454A (en) | 1976-05-25 |
| FR2272736A1 (en) | 1975-12-26 |
| CS191266B2 (en) | 1979-06-29 |
| DE2524223A1 (en) | 1975-12-11 |
| AU8167775A (en) | 1976-12-02 |
| ZA753372B (en) | 1976-05-26 |
| GB1500036A (en) | 1978-02-08 |
| IN143866B (en) | 1978-02-18 |
| FR2272736B1 (en) | 1981-09-25 |
| ES438131A1 (en) | 1977-02-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US2921018A (en) | Method for improving used cracking catalysts | |
| EP0535619B1 (en) | Process for regenerating a deactivated catalyst | |
| US4089806A (en) | Method for rejuvenating hydroprocessing catalysts | |
| JPH0224585B2 (en) | ||
| US2384315A (en) | Process for cracking crude hydrocarbon oil | |
| CA1055921A (en) | Reactivation of particulate catalyst masses | |
| CA2015388A1 (en) | Treatment of spent cracking catalysts | |
| CA2385439A1 (en) | Gasoline sulfur reduction in fluid catalytic cracking | |
| US2850462A (en) | Reactivation of metal-poisoned catalysts | |
| US2880168A (en) | Maintenance of catalyst activity using methyl cloride | |
| JPS6322183B2 (en) | ||
| US6406615B1 (en) | Hydrotreating process for residual oil | |
| KR930002227B1 (en) | Passivation of fcc catalysts | |
| EP0486764B1 (en) | Method of start-up of a contaminated hydrocarbon-conversion system using a contaminant-sensitive catalyst | |
| US2484828A (en) | Production of contact materials | |
| US4800185A (en) | Regeneraation of metal contaminated hydrocarbon conversion catalytsts | |
| US3211668A (en) | Rejuvenation of nitrogen compoundpoisoned catalysts | |
| US3835063A (en) | Regeneration of halogen promoted bimetallic reforming catalyst | |
| US2397505A (en) | Catalytic cracking and catalyst reactivation | |
| US2382472A (en) | Regeneration of catalysts | |
| US3122511A (en) | Cracking catalyst demetallization | |
| US7368409B2 (en) | Regeneration method of heterogeneous catalysts and adsorbents | |
| US4038209A (en) | Catalyst regeneration process | |
| US2254618A (en) | Treatment of spent catalysts | |
| US3590007A (en) | Process for regeneration of spent hydroconversion catalyst |