USRE22097E - Treatment of catalysts - Google Patents

Description

Reissued May 12, 194z I 22 097 UNITED STATES PAT ENT OFFICE TBEATMEN T F CATALYSTS Bryan D. Wells, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, 111., a

corporation of Delaware No Drawing. Original No. 2,225,811, dated December 24, 1940, Serial No. 238,065, October 31, 1938. Application for reissue August 4, 1941,

Serial N0. 405,410

8 Claims.

drogenation catalysts composed of a relatively inert support upon which nickel has been deposited by reduction of oxides which in turn have been produced by the calcination of such cornpounds as nickel hydroxide, nickel nitrate, nickel carbonate, etc.

During the course of hydrogenation reactions, small but definite amounts of heavy carbonaceous materials'are formed and these deposits upon the surface and in the pores of the active catalytic metals while any sulfur present in the materials undergoing reaction combines with the metal catalysts to'form sulfides which further coat and impair their activity. These poisoning In the second step, the temperature employed will be dependent upon the amount of sulfur present as sulfide and may vary from approximately 400 to 800 F. Treatment is continued unltl substantially all of the carbonaceous material has been burned oil, which can be determined by tests on. samples drawn from the catalyst bed. At the end of the second step, no compound of nickel should be present except oxides and sulfate, the former being in predominating amounts.

Prior to the third step of the process, the catalyst bed is cooled and treated with dilute aqueous solutions of alkalis such as the hydroxides of the alkali metals and/or ammonia to precipitate nickel hydroxide and form water soluble sulfates.

reactions are more generally in evidence, the

-moderate temperatures to remove volatile organic matter; (2) oxidation of residual carbonaceous deposits to carbon oxides and water and of nickel As will be shown in a later example, weak alkalis are first applied, the solutions drained and the mass dried with air after which stronger alkalis are applied to complete the precipitation of nickel hydroxide. I

The fourth step consists in careful water washing at ordinary temperatures to remove traces of soluble sulfates, and in the fifth step, the cata-' lyst mass is dried by passing a stream of hot inert gases thereover, and finally reduced with hydrogen at a moderate temperature usually within the range of 500-800 F.

The present process is principally applicable to composite catalysts comprising relatively inert materials supporting reduced metals and has been found highly advantageous in the reactivation of catalysts consisting of nickel or nickel and copper supported on kieselguhr, these catalysts having been made by pelleting kieselguhr and hydrated nickel carbonate, using lubricants such as graphite in the pilling operation and reducing directly with hydrogen at temperatures of the order of 500-800 F. These catalysts are highly active in hydrogenating olefinic hydrocarbons to produce their saturated counterparts.

The operations of the process are of a rela- V tively simple character and enable the complete sulfide to nickel sulfate by the application of a moist air or oxygen; (3) precipitation of nickel hydroxides from nickel sulfate in situ by the use of dilute aqueous alkalis such as ammonium hydroxide of caustic soda; (4) washing to remove sulfates; (5) drying and reducing with hydrogen to generate nickel.

Step 1 of the process is employed to remove substantially all adheringmaterials which can be volatllized by steam so that less load is placed be volatilized.

restoration of the catalytic properties of composite hydrogenating catalysts. The only reagents necessary are steam, air, aqueous alkalis,

hydrogen and wash water, and in the case of composite catalysts which have been employed in chambers of multi-tubular elements in hydrogenating reactions, the catalytic activity can be completely restored without removing the catalysts from their containers. It is particularly to 2 tion of'imposing exactly corresponding limitations upon the inventions proper scope. A spent catalysts, bed of x pellets consisting originally of kieselguhr, graphite, and nickel was first steamed for one hour at a tem-' perature of 400 F. to remove adhering oils and other 'volatilizable materials. Following the passage of the steam, a mixture Consisting of 94% nitrogen and 6% air was passed through the were maintained for one hour after which the temperature was again raised to 550 F. and maintained at that temperature for four hours.- The temperature was then decreased to 500 F. and the percentage of air in the gas mixture in-, creased to approximately 15%. These last conditions were maintained for three hours after which the heating was stopped and the material allowed to cool to 180 F. with the same gas mixture flowing over the catalyst.

When the catalyst temperature had fallen to 180 F., the pellets were wetted with an approximately 3% ammonium hydoxide solution, after which the excess solution was drained ofi and air was blown through the wet material-at an increasing rate for four hours. was again wetted with approximately 10% ammonium hydroxide solution and a larger amount of 1% solution was pumped through during a period of approximately 1 hour. After this time a distilled water wash was substituted and the washing continued until no test forsulfates was obtained in the efiluent. The catalyst bed was then dried by passing therethrough a stream of nitrogen heated to 220 F. and reduction of nickel oxides was brought about by contacting with a stream of hydrogen at temperatures from 500 to 700 F. over a period of four hours.

Considering activities on a basis of abilityto hydrogenate a mixture of octenes under a given set of conditions of temperature, pressure, and hydrogen concentration, the activity of the spent catalyst prior to the above treatment had been reduced to 20% of its original value calculated on the basis of the saturation produced in the mixture of octenes. After the reactivating treat.-

ment, it was found that the catalytic activity had been increased to 100% of the original value.

I claim as my invention:

1. A process for regenerating spent metal catalysts in which the metal is present in the sulfide form, which comprises subjecting the spent catalyst to oxidation by means of an oxygen-containing gas to convert the metal sulfide to sulfate, then treating the catalyst with aqueous alkali solution to precipitate metal hydroxide from the sulfate, and subsequently reducing with hydrogen to formjree metal. 1

i 2. A process for regenerating spent metal catalysts in which the metal is present in the sulfide form, which comprises subjecting the spentpatalyst to the action of air at a temperature of from 400 to 800 F, to convert the metal, sulfide to sulfate, then treating the catalyst with aqueous alkali solution to precipitate metal hydroxide from th sulfate, and subsequently reducing with hydrogen at. a temperature of from 500 to 800 F. to formfree metal.

3. A process for regenerating spent nickel catalysts in which the nickel is-present in'the sulfide form, which comprises subjecting the,

spent catalyst to oxidation by means of an oxy- The catalyst bed gen-containing gas to convert the nickel sulfide to sulfate, then. treating the catalyst with aqueous alkali solution to precipitate nickel hydroxide from the sulfate, and subsequently reducing with hydrogen to form free nickel.

4. A process for regenerating spent nickel catalysts in which the nickel is present in the sulfide form, which comprises subjecting the spent catalyst to the action of air at a temperature of from 400 to 800 F., to convert the nickel sulfide to sulfate, then treating the catalyst with aqueous alkali solution to precipitate nickel-hydroxide from the sulfate, and subsequently reducing with hydrogen at a temperature of from 500 to 800 F. to form free nickel,

5. A process for regenerating a spent metal catalyst in which a portion of the metal is present in a sulfurized condition which comprises subjecting the spent catalyst to the action of air at a temperature of from about 400t0 about 800 F. to convert a portion of the sulfurized metal to metal sulfate,,cooling to about 180 -F., wettingv the catalyst with a weak aqueous alkali and further subjecting the wetted catalyst to the action of air to convert a further substantial portion of the sulfurized metal to sulfate, treating the catalyst with a further quantity of an aqueous alkali solution to precipitate metal hydroxide from the sulfate, washing to remove sulfate ions and subsequently reducing with hydrogen at a temperature of from about 500 to about 800 F.

to form free metal.

6. A process for regenerating a spent nickel catalyst inwhich a portion of the nickel is present in a sulfurized condition which comprises subjecting the spent catalyst to the action of air at a temperature of from about 400 to about 800 F: to convert a portion ofthe sulfurized nickel to nickel sulfate, cooling to about 180 F., wetting the catalyst with a weak aqueous alkali and further subjecting the wetted catalyst to the action of air to convert a further substantial portion of the sulfurized nickel to sulfate, treating the catalyst with a further quantity of an. aqueous alkali solution to precipitate nickel hydroxidefrom the sulfate and subsequently washing to remove sulfate ions and reducing with hydrogen at a temperature of from about 500 to about 800F. to form free nickel.

7. A process for regenerating a spent sulfurized metal catalyst which comprises subjecting said catalyst to the action of air at a temperature of from about 400 to about 800 F., cooling the catalyst to a temperature of about 180 F., wetting the catalyst with an aqueousalkali and further subjecting the wetted catalyst to the action of air, treating the catalyst with a further quantity of aqueous alkali solution, washing the catalyst with water, drying and treating with hydro- 'gen at a temperature of from about 500 to about 800 F.

8. A process for regenerating a spent sulfurized nickel catalyst which comprises subjecting said catalyst to the action of air at a temperature of from about 400 to about 800 F., coolingthe catalyst to a temperature of about 180 F., wetting the catalyst with an aqueous alkali and further subjecting the wetted catalyst to the action of air, treating the catalyst with a further quan tity of aqueous alkali solution, washingthe catalyst with water, drying and treating with hydrogen at a temperature of from about 500 to about