CA1254191A - Reactivation of noble metal-containing catalyst materials - Google Patents
Reactivation of noble metal-containing catalyst materialsInfo
- Publication number
- CA1254191A CA1254191A CA000495494A CA495494A CA1254191A CA 1254191 A CA1254191 A CA 1254191A CA 000495494 A CA000495494 A CA 000495494A CA 495494 A CA495494 A CA 495494A CA 1254191 A CA1254191 A CA 1254191A
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- Canada
- Prior art keywords
- catalyst
- coke
- volume percent
- sulfiding
- noble metal
- Prior art date
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Abstract
REACTIVATION OF NOBLE METAL-CONTAINING
CATALYST MATERIALS
ABSTRACT OF THE DISCLOSURE
A coke-deactivated noble metal-containing catalyst is sulfided with a sulfiding agent, e.g., H2S in H2, then coke is burned from the sulfided catalyst by contacting the catalyst with oxygen and then the catalyst is reduced with a reducing agent, e.g., H2. The process permits burning off coke while avoiding excessive agglomeration of the noble metals on the catalyst.
CATALYST MATERIALS
ABSTRACT OF THE DISCLOSURE
A coke-deactivated noble metal-containing catalyst is sulfided with a sulfiding agent, e.g., H2S in H2, then coke is burned from the sulfided catalyst by contacting the catalyst with oxygen and then the catalyst is reduced with a reducing agent, e.g., H2. The process permits burning off coke while avoiding excessive agglomeration of the noble metals on the catalyst.
Description
1254~
REACTIVATION OF NOBLE METAL-CONTAINING
.
CATALYST MATERIALS
The invention relates to a process of reactivating catalysts. In particular, it relates to the reactivation of noble metal-containing zeolite catalysts which have been deactivated by coke build-up. Catalysts which may be reactivated by the process of the present nvention include those that have become deactivated during hydrocarbon hydroprocesses, such as the reforming or catalytic dewaxing of hydrocarbon feedstocks.
Reactivation of platinum catalysts in reforming is known.
Chlorine and oxygen catalyst reactivation are particularly well-known. U.S. Patent No. 2,906,702 to Brennan et al discloses a method of restoring an alumina-supported platinum catalyst after deactivation occurring during the reforming of hydrocarbons.
Deactivated platinum-alumina catalyst is contacted with a gaseous chlorine, fluorine, or other halogen or halogen-affording substance at an elevated temperature. U.S. Patent No. 3,134,732 to Kearby et al teaches reactivating noble metal catalyst supported on alumina by contacting the catalyst with halogen-containing gas, stripping excess halogen therefrom, and reducing the resulting catalyst with a hydrogen-containing gas. In this disclosure, the agglomerated metal is present on the surface of the alumina as small crystallites.
Regeneration of noble metal-loaded zeolite catalysts required certain procedural modifications to regain the activity of the metal. U.S. Patent No. 3,986,982 to Crowson et al treats deactivated platinum group metal-loaded zeolites by contacting them with a stream of an inert gas containing from û.5 to 20 percent volume of free oxygen and from 5 to 500 ppm volume of chlorine as chlorine, HCl, or an organic chlorine-containing material. The resulting catalyst is purged to remove residual oxygen and chlorine and then reduced in hydrogen at 200 to 600C.
12S~9l The treatment of regenerated noble metal-containing catalysts with sulfur compounds is also known. U.S. Patent No.
3,661,768 to Davis, Jr., et al. describes regenerating a bimetallic reforming catalyst such as platinum-rhenium on alumina and then contacting the catalyst with hydrogen sulfide to convert platinum to platinum sulfide. Prior to sulfiding, the catalyst is contacted with chlorine and steam to effect chlorination.
All of the above treatments require certain precautions owing to the corrosive nature of the halogens used. In addition, certain halogen materials employed in these processes add significantly to the cost of catalyst regeneration. To avoid the drawbacks associated with halogen use, it would be advantageous to reactivate catalysts in the absence of halogens. However, when deactivating coke present on a catalyst material is exposed to an oxidizing atmosphere consisting of oxygen and an inert gas, such as nitrogen, substantially all of the noble metal present on the catalyst becomes catalytically inactive.
A way has now been discovered to overcome these drawbacks.
Accordingly, the present invention provides a process for regenerating a coke-deactivated, noble metal containing catalyst which comprises removing coke from the catalyst by contacting the catalyst with an oxygen-containing gas and oxidizing the coke and then reducing the decoked catalyst with a reducing gas characterized by sulfiding the deactivated catalyst prior to coke removal.
The present invention provides a regenerated catalyst of enhanced activity which retains a substantial portion of its noble metal in a dispersed form. The process comprises sulfiding the aged catalyst, oxidizing the coke on the sulfided catalyst material with oxygen and then reducing the catalyst with hydrogen.
Suitable sulfiding agents for the purposes of the present invention include hydrogen sulfide compounds which decompose to yield H2S, e.g., light mercaptans, and compounds or substances which effectively sulfide the catalysts, e.g., a naphtha fraction spiked with 0.1 to 10 wt c~ disulfides. Hydrogen sulfide is iZS'~
preferred because it is very active and readily available in refineries. Preferably, the sulfiding agent is combined with hydrogen to form a mixture containing 0.1 to 10 volume percent sulfiding agent, e.g., hydrogen sulfide, preferably about 1 to 2 volume percent. Suitable conditions for sulfiding include temperatures of 250 to 500C, preferably 300 to 450~C, say about 400C, typically 350 to 40ûC. Pressures may range from slightly above or below atmospheric to 3549 kPa (500 psig), preferably about 791 to 2170 kPa (150 to 250 psig). Preferably, the deactivated catalyst is sulfided at least until "breakthrough" of the sulfiding agent at the outlet of the sulfiding vessel, i.e., the sulfiding agent is detected in the sulfiding vessel effluent.
The sulfide addition step preferably adds 0.005 to 10 wt.%
sulfur prior to regeneration, with 0.01 to 3 wt. % sulfur addition giving very good results. In many instances, adding as little as 0.1 or 0.2 wt. % sulfur is enough.
The coke on sulfided catalyst is burned at moderate temperatures and oxygen concentrations. Temperatures of 200 to 500C, preferably 350 to 450C, and pressures of atmospheric to 2859 kPa (400 psig), preferably 1136 to 1825 kPa (150 to 250 psig) may be used. Mild oxidizing conditions minimize alteration in the crystal structure of the zeolite being treated. High temperatures, and high oxygen concentrations favor coke burn off. Usually the temperature of the regeneration gas, and the oxygen concentration, will be set so that temperature in the catalyst bed during regeneration will not exceed 500C, and preferably not above 400 to 450C.
Sulfided catalyst is contacted with a ~as stream containing oxygen. Generally, the gas stream may contain 0.5 to 20, and preferably 1 to 10 volume percent 2' most preferably 1 to 3 volume percent 2 The gas stream may contain other compounds, e.g., 100 to 2 volume ppm S02, which prevents or reduces agglomeration of the noble metals during the removal of coke.
l~S419~
Dispersion of the noble metals can be measured by hydrogen chemisorption, e.g., Temperature Programmed Desorption (TPD) of hydrogen. This technique indicates the extent of noble metal agglo-meration. Details of this analytical technique may be found in "The Stoichiometry of Hydrogen and Cû Chemisorption of Ir/ -Al203", Vol. 78, Journal of Catalysis, pp. 319-326, Krishnamurthy et al., (1982). Alternatively, such dispersion can be measured by X-ray line broadening techniques which detect the weight percent of noble metal agglomerates of greater than 50 angstroms.
The catalyst is reduced after the coke burn. Any suitable reducing agent, preferably hydrogen, may be used. The catalyst contacts the reducing agent at 30û to 500~C, preferably 350 to 450C
for a time sufficient to reduce the metal, usually l to lO hours, preferably about 2 to 5 hours. Where hydrogen is used, reduction is usually carried out at atmospheric to 2859 kPa (400 psig), prefer-ably 1136 to 1825 kPa (150 to 250 psig). Hydrogen sulfide may be employed as a reducing agent in conjunction with or as a substitute for hydrogen.
The present invention can be used with any noble metal containing catalyst, either on an amorphous support or on a zeolite containing support.
Many reforming catalysts consist of 0.1 to 2 wt.% noble metal on alumina or other support. Typically, these catalysts contain 0.1 to 1% halogen. Platinum is almost always present, either alone or in combination with other metals such as rhenium or iridium. ~any of these reforming catalysts are sulfided before use in the reforming process. Sulfiding of fresh or regenerated, reforming catalysts is not equivalent to adding more sulfur to the catalyst after it has been at least partially deactivated but before it has been regenerated.
The process of the present invention is especially useful when the noble metals are on a zeolite containing support.
The zeolites which may be rejuvenated by the process of the present invention include large pore zeolites such as Zeolite Y, zeolite beta, ZSM-3, ZSM-4, ZSM-18 and ZSM-20, as well as zeolites l~S'~91 having a constraint index of about 1 to 12 and silica to alumina mole ratio greater than about 12. Examples of such materials include ZSM-5, ZSM-ll, ZSM-5/ZSM-ll intermediates, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48 and other similar materials.
Zeolite beta is described in U.S. 3,308,069.
ZSM-3 is described in U.S. Patent No. 3,415,736.
ZSM-4 is described in U.S. Patent No. 4,021,447.
ZSM-5 is described in U.S. Patents Nos. 3,702,886 and Re 29,948.
ZSM-ll is described in U.S. Patent No. 3,709,979.
ZSM-5/ZSM-ll intermediate compositions are described in U.S. Patent No. 4,229,424.
ZSM-12 is described in U.S. Patent No. 39832,449.
ZSM-18 is described in U.S. Patent No. 3,950,496.
ZSM-20 is described in U.S. Patent No. 3,972,983.
ZSM-23 is described in U.S. Patent No. 4,076,842.
ZSM-35 is described in U.S. Patent No. 4,016,245.
ZSM-38 is described in U.S. Patent No. 4,046,859.
ZSM-48 is described in U.S. Patent No. 4,234,231.
Particularly preferred zeolites for the purposes of the present invention are those which have silica-to-alumina mole ratios greater than 20, preferably greater than 70 or 100.
The catalyst treated by the process of the present invention contains at least one noble metal such as platinum, palladium, iridium, osmium, rhodium, rhenium and ruthenium or mixture in amounts ranging from û.05 to 5 wt %, preferably 0.1 to 2 wt %, most preferably, 0.3 to 0.9 wt %. These noble metals are generally associated with and supported on a zeolite catalyst. The process may also be used to regenerate multimetallic catalysts which contain one of the above noble metals and another metal selected from Groups IB, IVB, VIIA, or VIII of the Periodic Table. The zeolite catalyst treated can be binder free or it may contain an inorganic oxide binder such as alumina, silica, silica-alumina, magnesia, titania, zirconia, or thoria.
1~54~91 This invention will be better understood by reference to the following examples.
Example 1 lO grams of a catalyst comprising zeolite beta and alumina (65~35 wt ratio) and 0.59 wt.% Pt was coked an~ deactivated. The deactivated catalyst was sulfided to breakthrough with H2 containing 2 volume percent H2S at 400C and 9 pressure just slightly above atmospheric at the inlet to the reactor. The sulfided catalyst was then contacted with a gas containing 96.3 volume percent N2, 3 volume percent 2 and 0.7 volume percent 52 at 400 to 450C for 0.5 hours to burn off the coke and thereafter reduced in H2 at 450C. Gas flows were roughly constant in each step, about 1.4 cc/second of gas, at standard conditions. The catalyst was measured by hydrogen chemisorption for platinum dispersion. The regenerated catalyst had a platinum dispersion of 0.33 compared wih a dispersion of 0.57 for fresh catalyst.
Example 2 (Prior Art~
A lO g sample of the coked catalyst of Example 1 was decoked, using the same apparatus and procedure, with 97 volume percent N2 and 3 volume percent 2 at 400 to 450C. The decoked catalyst was then reduced for one hour at 450C in hydrogen.
Platinum dispersion, as measured by hydrogen chemisorption, was 0.
A comparison of Examples l and 2 indicates that the reactivation process of the present invention is e~fective in retaining a significant portion of the initial Pt dispersion of a catalyst, which would otherwise be lost by conventional regeneration treatment.
Example 3 A catalyst of 0.59 wt % Pt on of zeolite beta and alumina (65/35) was deactivated by coke deposition. The deactivated catalyst was sulfided, using the same apparatus and procedure as in i2S4191 Example 1, in a glass reactor to breakthrough with a mixture of 2%
H2S/H2 at 400C. The sulfided catalyst was decoked with 97%
N2 and 3% 2 at 400C to 450C. The catalyst was then reduced for one hour at 450C. The regenerated catalyst had a platinum dispersion, by hydrogen chemisorption, of 0.1 compared with a dispersion of 0.57 for a fresh catalyst.
Example 4 This test was done in a high pressure test reactor, at conditions closer to those likely to be experienced in a commercial plant. One hundred cc of a fresh 0.6 weight percent platinum on steamed 65 wt % zeolite beta/ 35 wt % alumina catalyst was presulfided with 2 volume percent H2S/98 volume percent H2 at 2859 kPa (400 psig) at 370C (700F) for two hours until H25 breakthrough. Gas flows in this, and succeeding steps, was 28.3 dm3/s, at standard conditions (1.0 standard cubic foot per hour).
The temperature was then increased to 430C (800F) and the feed changed to 0.5 volume percent H2S/99.5 volume percent H2. These conditions were held for two hours until H2S breakthrough. The catalyst was then purged with N2 at 230C (450F) for six hours.
Platinum agglomeration was measured by X-ray line broadening analysis to detect platinum agglomerates greater than about 50 to 75 angstroms.
Coke was then burned at 800 kPa (100 psig), in 0.7 to 1%
oxygen in nitrogen and a maximum burn temperature of 450C (850F).
Platinum agglomeration was then measured.
The process was repeated except a catalyst containing 15 weight percent coke was substituted for the fresh catalyst.
Finally, both catalysts were again treated by the above process except that H2 was substituted for the H2S/H2 mixture.
The results are given in the following Table.
;l~S'~
Pt. X-ray peak area, %
Catalyst before burn after burn Fresh catalyst H25~H2 treated 2 5 H2 treated 5 72 Coked catalyst H2S/H2 treated 2 25 H2 treated 2 47 These results show that catalysts (both fresh and coked) treated with H2S/H2 be~ore oxidative regeneration showed drastic reduction in the extent of metal agglomeration.
REACTIVATION OF NOBLE METAL-CONTAINING
.
CATALYST MATERIALS
The invention relates to a process of reactivating catalysts. In particular, it relates to the reactivation of noble metal-containing zeolite catalysts which have been deactivated by coke build-up. Catalysts which may be reactivated by the process of the present nvention include those that have become deactivated during hydrocarbon hydroprocesses, such as the reforming or catalytic dewaxing of hydrocarbon feedstocks.
Reactivation of platinum catalysts in reforming is known.
Chlorine and oxygen catalyst reactivation are particularly well-known. U.S. Patent No. 2,906,702 to Brennan et al discloses a method of restoring an alumina-supported platinum catalyst after deactivation occurring during the reforming of hydrocarbons.
Deactivated platinum-alumina catalyst is contacted with a gaseous chlorine, fluorine, or other halogen or halogen-affording substance at an elevated temperature. U.S. Patent No. 3,134,732 to Kearby et al teaches reactivating noble metal catalyst supported on alumina by contacting the catalyst with halogen-containing gas, stripping excess halogen therefrom, and reducing the resulting catalyst with a hydrogen-containing gas. In this disclosure, the agglomerated metal is present on the surface of the alumina as small crystallites.
Regeneration of noble metal-loaded zeolite catalysts required certain procedural modifications to regain the activity of the metal. U.S. Patent No. 3,986,982 to Crowson et al treats deactivated platinum group metal-loaded zeolites by contacting them with a stream of an inert gas containing from û.5 to 20 percent volume of free oxygen and from 5 to 500 ppm volume of chlorine as chlorine, HCl, or an organic chlorine-containing material. The resulting catalyst is purged to remove residual oxygen and chlorine and then reduced in hydrogen at 200 to 600C.
12S~9l The treatment of regenerated noble metal-containing catalysts with sulfur compounds is also known. U.S. Patent No.
3,661,768 to Davis, Jr., et al. describes regenerating a bimetallic reforming catalyst such as platinum-rhenium on alumina and then contacting the catalyst with hydrogen sulfide to convert platinum to platinum sulfide. Prior to sulfiding, the catalyst is contacted with chlorine and steam to effect chlorination.
All of the above treatments require certain precautions owing to the corrosive nature of the halogens used. In addition, certain halogen materials employed in these processes add significantly to the cost of catalyst regeneration. To avoid the drawbacks associated with halogen use, it would be advantageous to reactivate catalysts in the absence of halogens. However, when deactivating coke present on a catalyst material is exposed to an oxidizing atmosphere consisting of oxygen and an inert gas, such as nitrogen, substantially all of the noble metal present on the catalyst becomes catalytically inactive.
A way has now been discovered to overcome these drawbacks.
Accordingly, the present invention provides a process for regenerating a coke-deactivated, noble metal containing catalyst which comprises removing coke from the catalyst by contacting the catalyst with an oxygen-containing gas and oxidizing the coke and then reducing the decoked catalyst with a reducing gas characterized by sulfiding the deactivated catalyst prior to coke removal.
The present invention provides a regenerated catalyst of enhanced activity which retains a substantial portion of its noble metal in a dispersed form. The process comprises sulfiding the aged catalyst, oxidizing the coke on the sulfided catalyst material with oxygen and then reducing the catalyst with hydrogen.
Suitable sulfiding agents for the purposes of the present invention include hydrogen sulfide compounds which decompose to yield H2S, e.g., light mercaptans, and compounds or substances which effectively sulfide the catalysts, e.g., a naphtha fraction spiked with 0.1 to 10 wt c~ disulfides. Hydrogen sulfide is iZS'~
preferred because it is very active and readily available in refineries. Preferably, the sulfiding agent is combined with hydrogen to form a mixture containing 0.1 to 10 volume percent sulfiding agent, e.g., hydrogen sulfide, preferably about 1 to 2 volume percent. Suitable conditions for sulfiding include temperatures of 250 to 500C, preferably 300 to 450~C, say about 400C, typically 350 to 40ûC. Pressures may range from slightly above or below atmospheric to 3549 kPa (500 psig), preferably about 791 to 2170 kPa (150 to 250 psig). Preferably, the deactivated catalyst is sulfided at least until "breakthrough" of the sulfiding agent at the outlet of the sulfiding vessel, i.e., the sulfiding agent is detected in the sulfiding vessel effluent.
The sulfide addition step preferably adds 0.005 to 10 wt.%
sulfur prior to regeneration, with 0.01 to 3 wt. % sulfur addition giving very good results. In many instances, adding as little as 0.1 or 0.2 wt. % sulfur is enough.
The coke on sulfided catalyst is burned at moderate temperatures and oxygen concentrations. Temperatures of 200 to 500C, preferably 350 to 450C, and pressures of atmospheric to 2859 kPa (400 psig), preferably 1136 to 1825 kPa (150 to 250 psig) may be used. Mild oxidizing conditions minimize alteration in the crystal structure of the zeolite being treated. High temperatures, and high oxygen concentrations favor coke burn off. Usually the temperature of the regeneration gas, and the oxygen concentration, will be set so that temperature in the catalyst bed during regeneration will not exceed 500C, and preferably not above 400 to 450C.
Sulfided catalyst is contacted with a ~as stream containing oxygen. Generally, the gas stream may contain 0.5 to 20, and preferably 1 to 10 volume percent 2' most preferably 1 to 3 volume percent 2 The gas stream may contain other compounds, e.g., 100 to 2 volume ppm S02, which prevents or reduces agglomeration of the noble metals during the removal of coke.
l~S419~
Dispersion of the noble metals can be measured by hydrogen chemisorption, e.g., Temperature Programmed Desorption (TPD) of hydrogen. This technique indicates the extent of noble metal agglo-meration. Details of this analytical technique may be found in "The Stoichiometry of Hydrogen and Cû Chemisorption of Ir/ -Al203", Vol. 78, Journal of Catalysis, pp. 319-326, Krishnamurthy et al., (1982). Alternatively, such dispersion can be measured by X-ray line broadening techniques which detect the weight percent of noble metal agglomerates of greater than 50 angstroms.
The catalyst is reduced after the coke burn. Any suitable reducing agent, preferably hydrogen, may be used. The catalyst contacts the reducing agent at 30û to 500~C, preferably 350 to 450C
for a time sufficient to reduce the metal, usually l to lO hours, preferably about 2 to 5 hours. Where hydrogen is used, reduction is usually carried out at atmospheric to 2859 kPa (400 psig), prefer-ably 1136 to 1825 kPa (150 to 250 psig). Hydrogen sulfide may be employed as a reducing agent in conjunction with or as a substitute for hydrogen.
The present invention can be used with any noble metal containing catalyst, either on an amorphous support or on a zeolite containing support.
Many reforming catalysts consist of 0.1 to 2 wt.% noble metal on alumina or other support. Typically, these catalysts contain 0.1 to 1% halogen. Platinum is almost always present, either alone or in combination with other metals such as rhenium or iridium. ~any of these reforming catalysts are sulfided before use in the reforming process. Sulfiding of fresh or regenerated, reforming catalysts is not equivalent to adding more sulfur to the catalyst after it has been at least partially deactivated but before it has been regenerated.
The process of the present invention is especially useful when the noble metals are on a zeolite containing support.
The zeolites which may be rejuvenated by the process of the present invention include large pore zeolites such as Zeolite Y, zeolite beta, ZSM-3, ZSM-4, ZSM-18 and ZSM-20, as well as zeolites l~S'~91 having a constraint index of about 1 to 12 and silica to alumina mole ratio greater than about 12. Examples of such materials include ZSM-5, ZSM-ll, ZSM-5/ZSM-ll intermediates, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48 and other similar materials.
Zeolite beta is described in U.S. 3,308,069.
ZSM-3 is described in U.S. Patent No. 3,415,736.
ZSM-4 is described in U.S. Patent No. 4,021,447.
ZSM-5 is described in U.S. Patents Nos. 3,702,886 and Re 29,948.
ZSM-ll is described in U.S. Patent No. 3,709,979.
ZSM-5/ZSM-ll intermediate compositions are described in U.S. Patent No. 4,229,424.
ZSM-12 is described in U.S. Patent No. 39832,449.
ZSM-18 is described in U.S. Patent No. 3,950,496.
ZSM-20 is described in U.S. Patent No. 3,972,983.
ZSM-23 is described in U.S. Patent No. 4,076,842.
ZSM-35 is described in U.S. Patent No. 4,016,245.
ZSM-38 is described in U.S. Patent No. 4,046,859.
ZSM-48 is described in U.S. Patent No. 4,234,231.
Particularly preferred zeolites for the purposes of the present invention are those which have silica-to-alumina mole ratios greater than 20, preferably greater than 70 or 100.
The catalyst treated by the process of the present invention contains at least one noble metal such as platinum, palladium, iridium, osmium, rhodium, rhenium and ruthenium or mixture in amounts ranging from û.05 to 5 wt %, preferably 0.1 to 2 wt %, most preferably, 0.3 to 0.9 wt %. These noble metals are generally associated with and supported on a zeolite catalyst. The process may also be used to regenerate multimetallic catalysts which contain one of the above noble metals and another metal selected from Groups IB, IVB, VIIA, or VIII of the Periodic Table. The zeolite catalyst treated can be binder free or it may contain an inorganic oxide binder such as alumina, silica, silica-alumina, magnesia, titania, zirconia, or thoria.
1~54~91 This invention will be better understood by reference to the following examples.
Example 1 lO grams of a catalyst comprising zeolite beta and alumina (65~35 wt ratio) and 0.59 wt.% Pt was coked an~ deactivated. The deactivated catalyst was sulfided to breakthrough with H2 containing 2 volume percent H2S at 400C and 9 pressure just slightly above atmospheric at the inlet to the reactor. The sulfided catalyst was then contacted with a gas containing 96.3 volume percent N2, 3 volume percent 2 and 0.7 volume percent 52 at 400 to 450C for 0.5 hours to burn off the coke and thereafter reduced in H2 at 450C. Gas flows were roughly constant in each step, about 1.4 cc/second of gas, at standard conditions. The catalyst was measured by hydrogen chemisorption for platinum dispersion. The regenerated catalyst had a platinum dispersion of 0.33 compared wih a dispersion of 0.57 for fresh catalyst.
Example 2 (Prior Art~
A lO g sample of the coked catalyst of Example 1 was decoked, using the same apparatus and procedure, with 97 volume percent N2 and 3 volume percent 2 at 400 to 450C. The decoked catalyst was then reduced for one hour at 450C in hydrogen.
Platinum dispersion, as measured by hydrogen chemisorption, was 0.
A comparison of Examples l and 2 indicates that the reactivation process of the present invention is e~fective in retaining a significant portion of the initial Pt dispersion of a catalyst, which would otherwise be lost by conventional regeneration treatment.
Example 3 A catalyst of 0.59 wt % Pt on of zeolite beta and alumina (65/35) was deactivated by coke deposition. The deactivated catalyst was sulfided, using the same apparatus and procedure as in i2S4191 Example 1, in a glass reactor to breakthrough with a mixture of 2%
H2S/H2 at 400C. The sulfided catalyst was decoked with 97%
N2 and 3% 2 at 400C to 450C. The catalyst was then reduced for one hour at 450C. The regenerated catalyst had a platinum dispersion, by hydrogen chemisorption, of 0.1 compared with a dispersion of 0.57 for a fresh catalyst.
Example 4 This test was done in a high pressure test reactor, at conditions closer to those likely to be experienced in a commercial plant. One hundred cc of a fresh 0.6 weight percent platinum on steamed 65 wt % zeolite beta/ 35 wt % alumina catalyst was presulfided with 2 volume percent H2S/98 volume percent H2 at 2859 kPa (400 psig) at 370C (700F) for two hours until H25 breakthrough. Gas flows in this, and succeeding steps, was 28.3 dm3/s, at standard conditions (1.0 standard cubic foot per hour).
The temperature was then increased to 430C (800F) and the feed changed to 0.5 volume percent H2S/99.5 volume percent H2. These conditions were held for two hours until H2S breakthrough. The catalyst was then purged with N2 at 230C (450F) for six hours.
Platinum agglomeration was measured by X-ray line broadening analysis to detect platinum agglomerates greater than about 50 to 75 angstroms.
Coke was then burned at 800 kPa (100 psig), in 0.7 to 1%
oxygen in nitrogen and a maximum burn temperature of 450C (850F).
Platinum agglomeration was then measured.
The process was repeated except a catalyst containing 15 weight percent coke was substituted for the fresh catalyst.
Finally, both catalysts were again treated by the above process except that H2 was substituted for the H2S/H2 mixture.
The results are given in the following Table.
;l~S'~
Pt. X-ray peak area, %
Catalyst before burn after burn Fresh catalyst H25~H2 treated 2 5 H2 treated 5 72 Coked catalyst H2S/H2 treated 2 25 H2 treated 2 47 These results show that catalysts (both fresh and coked) treated with H2S/H2 be~ore oxidative regeneration showed drastic reduction in the extent of metal agglomeration.
Claims (10)
1. A process for regenerating a coke-deactivated, noble metal containing catalyst which comprises removing coke from the catalyst by contacting the catalyst with an oxygen-containing gas and oxidizing the coke and then reducing the decoked catalyst with a reducing gas characterized by sulfiding the deactivated catalyst prior to coke removal.
2. The process of claim 1 wherein the catalyst is sulfided with hydrogen sulfide.
3. The process of claim 2 wherein the catalyst is sulfided with gas containing 0.1 to 10 volume percent H2S.
4. The process of any preceding claim wherein the sulfiding temperature is 250 to 500°C and the pressure is atmospheric to 3549 kPa (500 psig).
5. The process of any of claims 1 to 3 wherein the oxygen-containing gas contains 1 to 3 volume percent oxygen.
6. The process of any of claims 1 to 3 wherein sulfiding is effected by contacting deactivated catalyst with 2 volume percent H2S/98 volume percent H2 mixture followed by contact with a 0.5 volume percent H2S/99.5 volume percent H2 mixture.
7. The process of any of claims 1 to 3 wherein the sulfiding step adds 0.05 to 10% wt.% sulfur, calculated on an elemental sulfur basis, to the catalyst.
8. The process of any of claims 1 to 3 wherein the sulfiding step adds 0.01 to 3.0% wt.% sulfur, calculated on an elemental sulfur basis, to the catalyst.
9. The process of any of claims 1 to 3 wherein the catalyst is on an amorphous support.
10. The process of any of claims 1 to 3 wherein the catalyst contains a zeolite.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000495494A CA1254191A (en) | 1984-04-26 | 1985-11-15 | Reactivation of noble metal-containing catalyst materials |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/604,268 US4555495A (en) | 1984-04-26 | 1984-04-26 | Reactivation of noble metal-containing zeolite catalyst materials |
| CA000495494A CA1254191A (en) | 1984-04-26 | 1985-11-15 | Reactivation of noble metal-containing catalyst materials |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1254191A true CA1254191A (en) | 1989-05-16 |
Family
ID=25670839
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000495494A Expired CA1254191A (en) | 1984-04-26 | 1985-11-15 | Reactivation of noble metal-containing catalyst materials |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1254191A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115254201A (en) * | 2022-08-22 | 2022-11-01 | 中国科学院兰州化学物理研究所 | Method for regenerating nano metal-phosphorus-carbon catalyst by hydrogen reduction |
-
1985
- 1985-11-15 CA CA000495494A patent/CA1254191A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115254201A (en) * | 2022-08-22 | 2022-11-01 | 中国科学院兰州化学物理研究所 | Method for regenerating nano metal-phosphorus-carbon catalyst by hydrogen reduction |
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