US2208616A - Reactivation of spent hydrogenation catalysts - Google Patents

Description

Patented July 23, 1940 a 2,208,616

UNITED STATES P ATENT OFFICE REACT'IVATION OF SPENT HYDROGENA- TION CATALYSTS Victor E. Wellman and Waldo L. Semon, Silver Lake, Ohio, assignors to The B. F. Goodrich Company, New York, N. Y., a corporation of New York I No Drawing. Application August 9, 1938, Serial No. 223,858

16 Claims. (Cl. 23-238) This invention relates to the reactivation of cage, which has become spent through use in a catalysts and in particular to a two-stage elechydrogenation process is placed in a solution of trolytic reactivation of spent massive metal hysodium hydroxide of about 6.5% concentration, drogenation catalysts. although solutions of 4% to 10% sodium hy- Prior to this invention it has been the pracdroxide concentrations are suitable. For con- 5 tice to submit spent massive metal hydrogenavenience the catalyst is usually enclosed in a tion catalysts to anodic oxidation in dilute solucloth or canvas bag which serves as a diaphragm. tions of mild alkalis. The older practice re- The catalyst is made the anode of an electrolytic quired that the anodic oxidation process be precell and a sheet of nickel is made the cathode of ceded by washing the catalysts thoroughly with the cell. A current, whose density is 0.05 to 0.10 10 organic solvents to remove completely the orampere per square inch as determined by asganic matter retained by the catalyst after use. suming the surface of the catalyst to be a solid Such organic matter constitutes a catalyst surface whose dimensions are the dimensions of poison and reduces the activity of the catalyst the cage enclosing the catalyst, and at a poten- X5 in the hydrogenation process. Expense arising tial of 4 to 10 volts, is passed through the cell. from the use and recovery of solvents by the The passage of the current will be accompanied older practice is eliminated by the practice of by no evolution of oxygen from the anode as the present invention. long as appreciable amounts of organic mate We have found that a two-stage anodic oxidarial remain on the catalyst. It is well to contion of the catalyst is amore economical and tinue the anodic oxidation of the catalyst for an 20 more satisfactory process for the reactivation hour after the appearance of evolved oxygen.

of spent massive metal catalysts than methods The catalyst is washed with water and is then heretofore used. In this two-stage anodic oxiready for the second stage of the process which dation process advantage is taken of the fact comprises anodic oxidation in a solution of a that organic poisons retained by the catalyst mild alkali, such as a 2.5% solution of sodium after use may be oxidized easily in strongly alkacarbonate in water or a saturated solution of calline electrolytic solutions. Very simple equipcium or strontium hydroxide, or even a dilute so- ,ment and inexpensive solutions are required to dium hydroxide solution, say of 1/25,000% to 2% accomplish the removal of the organic matter. concentration. It is well to surround the catalyst Furthermore, the time required to remove the with another diaphragm, such as a cloth or canorganic matter from the catalyst by electrolytic vas bag. The amperage and voltage of the curoxidation is usually less than is required by the rent employed in the second stage are similar to more. costly solvent washing of the catalyst. those employed in the first stage. During the After the removal of the organic matter by second stage of the reactivation process, a film anodic oxidation, the surface of the massive of tightly adhering black nickel oxide or permetal catalyst may be activatedby anodic oxioxide is formed on the massive metal. Four to dation in mildly alkaline solutions. 7 The actiforty-eight hours may be required to complete vation step consists of forming a tightly adherthe second stage of the reactivation process. At ing film of metallic oxide or peroxide on the surthe conclusion of the second stage, the catalyst face of the massive metal. Reduction in an is washed with distilled water until free of alka- 40 atmosphere of hydrogen at elevated temperaline material. Reduction of the oxide or pertures ordinarily completes the preparation of oxide to active catalytic nickel is accomplished the catalyst for use. by heating in an atmosphere of hydrogen, pref The process to be illustrated below may be used erably in the-hydrogenation vessel, for 1 to 2 for the reactivation of the well known massive hours at a temperature of 200 to 250 C. metal catalysts composed of such metals as cop'- Although the foregoing example of the invenper, nickel, or cobalt or alloys of these metals tion has been given in considerable detail, it is i with each other or with other metals such as understood that-wide variation may be used with chromium, platinum, palladium, iron, oralumirespect to materials and proportions of matenum, as well as mixtures of any of the above rials without departing from the scope and metals and alloys. spirit of the invention.

The invention may be more clearly understood -We claim: from the following detailed example: A massive A process f r reactivating spent massive nickel Cat y Such as nickel turnings. Wire metal hydrogenation catalysts contaminated with Chips. Contained in a Suitable Wire basket or organic materials which comprises subjecting the 55 catalyst to electrolytic anodic oxidation in a strongly alkaline solution, then subjecting the catalyst to electrolytic anodic oxidation in a mildly alkaline solution, then washing the catalyst with water and finaily reducing the catalyst in an atmosphere of hydrogen at an elevated temperature.

2. A process for reactivating spent massive metal hydrogenation catalysts contaminated with organic materials which comprises subjecting the catalyst to electrolytic anodic oxidation in a strongly alkaline solution of sodium hydroxide, then subjecting the catalyst to electrolytic anodic oxidation in a mildly alkaline solution, then washing the catalyst with water and finally reducing the catalyst in an atmosphere of hydrogen at an elevated temperature;

3. A process for reactivating spent massive metal hydrogenation catalysts contaminated with organic materials which comprises subjecting the catalyst to electrolytic anodic oxidation in a solution of sodium hydroxide of 4% to 10% concentration, then subjecting the catalyst to electrolytic anodic oxidation in a mildly alkaline solution, then washing the catalyst with water and finally reducing the catalyst in an atmosphere of hydrogen at elevated temperatures.

4. A process as defined by claim 3 in which the mildly alkaline solution is a solution of sodium carbonate of 1 to 5% concentration.

5. A process as defined by claim 3 in which the mildly alkaline solution is a saturated solution of an alkaline earth hydroxide.

6. A process as defined by claim 3 in which the mildly alkaline solution is a saturated solution of strontium hydroxide.

7. A process for reactivating spent massive metal catalysts contaminated with organic ma-- tcrials which comprises subjecting the catalyst to electrolytic anodic oxidation in a solution of sodium hydroxide of 4% to 10% concentration, then subjecting the catalyst to electrolytic anodic oxidation in a solution of sodium hydroxide of 1/25,000% to 2% concentration, then washing the catalyst with water and finally reducing the catalyst in an atmosphere of hydrogen at an elevated temperature.

8. A process as defined by claim 1 in which the catalyst is subjected to electrolytic anodic oxidation in a strongly alkaline solution until substantially all the organic matter has been oxidized off the catalyst as evidenced by a copious evolution of oxygen from the surface of the catalyst.

9. A process as defined byclaim 1 in which the catalyst is subjected to electrolytic anodic oxidation in a mildly alkaline solution until a tightly adhering film of metallic oxide or peroxide has been formed on the surface of the massive metal.

10. A process as defined by claim 7 in which the catalyst is subjected to electrolytic anodic oxidation in a solution of sodium hydroxide of 1/25,000% to 2% concentration until a tightly adhering film of metallic oxide or peroxide has been formedon the surface of the massive metal.

11. A process for reactivating spent massive nickel hydrogenation catalysts contaminated with organic materials which comprises subjecting the catalyst to electrolytic anodic oxidation in a solution of sodium hydroxide of about 6.5% concentration, until substantially all the organic matter has been oxidized ofi the catalyst as evidenced by a copious evolution of oxy t n from the surface of the catalyst, then subjecting the catalyst to electrolytic anodic oxidation in a mildof metallic oxide or peroxide has been formed on the surface of the massive nickel catalyst, then washing the catalyst with water and finally reducing the catalyst in an atmosphere of hydrogen at an elevated temperature.

12. A process as defined by claim 11 in which the mildly alkaline solution is a solution of sodium carbonate of 1% to 5% concentration.

13. A process as defined by claim 11 in which the mildly alkaline solution is a saturated solution of an alkaline earth hydroxide.

14. A process as defined by claim 11 in which the mildly alkaline solution is a saturated solution of strontium hydroxide.

15. A process as defined by claim 11 in which the mildly alkaline solution is a solution of sodium hydroxide of 1/25,000% to 2% concentration.

16. A process for reactivating spent massive nickel hydrogenation catalysts contaminated with organic materials which comprises subjecting the catalyst to electrolytic anodic oxidation in a solution of sodium hydroxide of about 65% concentration until substantially all the organic matter has been oxidized off the catalyst as evidenced by a copious evolution of oxygen from the surface of the catalyst, then subjecting the catalyst to electrolytic anodic oxidation in a solution of sodium carbonate of about 2.5% concentration until a tightly adhering film of metallic oxide or peroxide is formed on the surface of massive catalyst metal, in both of which preceding electrolytic anodic oxidations the current has a density of 0.05 to 0.10 ampere per square inch as determined by assuming the catalyst surface to be the solid surface, the dimensions of which are the dimensions of the cage enclosing the catalyst, then washing the catalyst with wa ter until substantially free of alkaline material and finally reducing the catalyst in an atmosphere of hydrogen for to 4 hours at a tempera ture of 200 to 300 C.