US1639981A

US1639981A - Producing oxidized carbon

Info

Publication number: US1639981A
Application number: US42111A
Authority: US
Inventors: Oliver W Storey; Gordon T Collinson
Original assignee: CF Burgess Laboratories Inc
Current assignee: CF Burgess Laboratories Inc
Priority date: 1925-07-07
Filing date: 1925-07-07
Publication date: 1927-08-23
Anticipated expiration: 1944-08-23

Description

- Patented Aug. 23, 1927.

STATES 'onvnn w. s'ron'a'x AND eoanon r. connmson, or

PATENT OFFICE.

Manson, Wisconsin, 'nssronons IO 0. F. BURGESS LABORATORIES, INC., OF DOVER, DELAWARE, A O OBPORA'1ION OF DELAWARE.

2H0 matting.

, This invention relates to the electrochemical production of solid carbon oxide or oxides having the properties of graphitic oxide. I

In a copending application of Bruce K. Brown, Serial No. 42,091, filed July 7, 1925', a method'for the electrochemical production of carbon oxides is disclosed; This method consists in mounting carbonaceous material as anode in an oxidizing electrolyte, such as 30% nitric acid atabout roonitempera ture, and passing an electric current having a density of about ten amperes per square foot of anode surface. The anode disintegrates toa sludge which is a mixture of carbon and oxide of carbon and may 'contain as high as 6% by weight of available oxygen. Carbon so-oxidized does not have the yellow color of pure graphitic oxide but has the dull black appearance of partially oxidized carbon and'it apparently is-iden tical or approximately identical with the product obtained b chemical oxidation. We

ave found that t e yield and oxygen percentage of the oxidized carbon product may be greatly increasedby suitably treating the electrodes that are to be disintegrated and further by the maintainin of the cell at the proper temperature w liile using elec- Q trodes so treated.

If a graphitic or other carbonaceous electrode is used as an anode in a dilute nitric acid or other suitable electrolite for the production of oxidized carbon t e electrode disintegrates at a rate depen upon the composition of the electro yte current density, temperature of the electro yte and composition of the electrode. Usuall an untreated anode which is disintegrate -in dilute 40 nitric acid at room tem erature disintegrates into a product that vanes over a wide range of particle sizes. The coarser articles may be as large as walnuts while the finer par ticles maypass through a 100 mesh screen.

5 All of these particles have a coating of oxidized carbon. on a weight basis the coarser particles have a relatively percenta en whereas the small particles will have a igh percentage if the coating. is of the same of the electrode.

It is "readily sun that raonucme oxrnrzan cannon.

Application filed my 7, 1935; Serial No. 42,111.

thickness on all particles. This is borne out I in Opractice, since the finely disintegrated p uct is found to have the higher percentage of available 0 gen. As an. illustration, if thatpart 0 the product from an untreated graphite anode which will pass through 100 mesh has an available oxygen percentage of about 5 percent, that part of the product which-passes through 40 mesh butis retained on 100 mesh will have an available oxygen percentage of about 4: per-' cent. Similarly the percentage of oxygen gradually decreases as the particles increase '11 size, until the coarsest particles contain considerably less than 1 per cent of oxygen. While it'is possible to utilize such a product industrially by screening out the coarser lumps, the coarse lumps represent a considerable loss, as they 0 en constitute 25 per cent or more of the entire product. We have found that the physical'disintegration of the anodes results from the penetration of the electrolyte The ordina molded electrode is porous to a considera 1e degree and into the pores in the case of graphite even the'i'ndividua-l 1 particles are porous to the'extent that they are laminated. As the electrolyte penetrates into the pores of the electrode, the current finds a path into the interior oi the electrodef, The electrolysis of the oxidizing electrolyte in the pores of the carbonaceous mate- -ri 1 results in the oxidation of the carbon to a solid oxide of carbon. The formation of the solid oxide is accompanied by a rceptible increase in volume or swel g. This causes physical disintegration; We have found that his may he ate ped. The remedy is to prevent the electro yte from entering the ores of the electrode.

I e easiest method of preventing the e'lectrolyte from entering the pores of the electrode is to fill: these with a; water ,Paralfiningi the out and it is' very he formation of can be made repellent, suchv as par electrpde is easily camel effective in reventing large lumps in fact, a product all of WhlC screen and per cent'of through a 60 mesh screen.

chwillpass will pass through a 20 meshfined. 'The melted para Not only does the parafiin prevent the disintegration of the electrode into large lumps but it also raises the percenta e of fixed oxygen. If an untreated graphlte electrode is disintegrated in a dilute nitric acid electrolyte, the fixed oxygen in the product passing throu h a 60 mesh screen will be approximate y five percent. By paraflining the anode, the disintegration product passing through 60 mesh will contain between 9 and 10 percent of oxygen. The increase in the fixed oxygen content obtained when an electrode is saturated with paraflin can probably be explained on the theory that theelectrolyte is prevented from penetrating the pores of the carbon, and instead, allows the electrolyte to penetrate the particles of carbon-and thereby rupture these. In the case of graphite, the electrolyte no doubt penetrates between the laminations, whereas this robably does not occur when the graphite 1s unparafiined. The 'paraflining results-in a much better penetration of the individual particles in contrast to the penetration of the electrolyte into the spaces around the'separate particles when unparafcarried out b' immersing it in smoking-hot fliii for a time long enough to efi'ectc'omplete enetration.

While para ing of the electrode is a cheap and efiicient' method for securing a disintegration into fine particles by confining this disintegration and oxidation to the surface of the electrode in contact with the electrolyte, it is possible to use a Wide va- 'riety of slmilar wax-like and other water repellant materials such as rosin. It is also ossible to use ordinary lubricating oils. iscarded crank case oil is a cheap and eflicient oil. which may be used to displace themore expensive refined. oils. The electrodes may-even be saturated with asoline, naptha, carbon tetrachloride and similar s01- vents, preferably those not easily attacked liiy the oxidizing reactions at the anode, helr efl'ect, however, is not as permanent,

since they are gradually driven out during v the electrolysis, so thatthe product contains particles of increasing size as the'electrolysis proceeds.

' It 1s notnecessary to use oils, waxes, or

' solvents of a water re llant nature, as an material will work w 1ch will'prevent di fusion of the electrolyte and confine the oxidation and disintegration to the surface of the electrode in contact with the electrolyte. An electrode thoroughly soaked in water will show the characteristics oi a parafiined anode for a time until the electrolyte has so diffused into .the interior that the li uid in thepores becomes conductive enoug to conduct the current sufiiciently to cause electrochemical oxidation. The electrode may be saturated with water solutions of paraflining of an anode may be' various chemical reagents which will cut down the rate of electrolyte diffusion.

It is also possible to saturate the electrode with a solution of a reagent such as sodium silicate which will form an insoluble precipitate or gel when it comes in contact with the electrolyte and will thereby prevent diffusion into the interior of the electrode. The precipitate should be of such a nature that it maybe subsequently washed out of the oxidized carbon, or if it is not washed out, should be harmless for the uses to which the oxidized carbon is put.

After the disintegration of the electrode, the powdered material is washed with water to remove the electrolyte or other chemicals that may be present If a moisture repellant is used to saturate. the electrode, this material is found in the disintegration product. This may be removed by suitable solvents, especiallysuch solvents as boil below 100 C. If the oxide of carbon has to be heated much above 100 C. there is an appreciable deterioration of the oxide. Carbon tetrachloride is an eflicient extracting agent when paraflin is used for saturating the electrode. It has the distinct advantage of not being flammable but has the disadvantage of high cost. Benzole is also an efiective agent, while ordinary gasoline has high boiling fractions present which cannot be driven readily from the colloidal oxide of carbon. The moisture repellant may be extracted in the cold but is more easily removed by boilin under a reflux condenser 100 and washing wit pure solvent, though this procedure tends to drive as some of the Y oxygen also. The solvent and the moisture repellant may be recovered by distillation.

If carbon tetrachloride or similar volatile solvents are used for saturating the electrodes during electrolysis it does not become necessary to extract these from the oxide of carbon. Simply heating the oxide to above the boilin point of the solvent drives off the solvent. Ihe advantages of this procedure are apparent.

If the oxide of carbon is used for depolarizing purposes in electric batteries it is essential that practically all of the moisture 1 repellant be extracted. Even small amounts .of parafiin will greatly decrease the conducresults are obtained below 0- G. At this low temperature the benzole freezes and acts as a solid moisture repellent. At ordinary temperatures the benzole is apparently ox'- idized more rapidly than the carbon and in some of our experiments has decreased the yield of oxidized carbon. These results indicate that it is. preferable to have a saturating medium which will be less readily. oxidized than the carbon, or the tem erature should be so regulated that this con ition is realized, as in the case of the benzole.

Throughout the specification and claims carbon is used in the broader sense and includes the graphitic state of the element.

Carbonaceous material .is used throughout rial containing free carbonin any of its allo-' the specification and claims to cover a matetropic forms.

We claim: 1, The method of producing pulverous, oxidized carbon consisting essentiall of-submitting an anode of-carbon which as been treated to confine the oxidation and disintegration of the electrode to the surface in contact with the electrolyte to an electric current in a bath having an oxidizing oxygen containin anion.

2. The met 0d of producin' *pulverous, oxidized carbon all of whic will pass through a 20 mesh screen consisting essentially of submitting ananode of carbon which has been treated to confine the oxidation and disintegration of the electrode to the surface in contact with the electrolyte to an electric current in a bath having an oxidizing-oxygen containing anion. a

3. The method of producing pulverous, oxidized carbon consistlng essentially of submitting an anode of carbon that has been impregnated with a moisture repellent to an electric current in a bath having an oxidizing oxygen containing anion.

4. The method of producin pulverous, oxidized carbon all of whic will pass through a 20 mesh screen consisting essentially of submitting any anode of carbon that has been impregnated with agmoisture repellent to an electric current in a bath having an oxldizing oxygen containing anion.

V peratures bonaceous material of such anode to an electric current in a bath having an oxidizing oxygen containing anion.

7. The method of producing oxidized carbon-in pulverous form consisting essentially of submitting an anode of carbonaceous material that has been impregnated with parafiin to an electric current in a bath having an oxidizing oxygen containing anion.

8. The method of producing pulverous, oxidized carbon consisting essentially of submitting an anode of carbon that has been impregnated with a moisture repellant to an electric current in a bath having an oxydizing oxygen containing anion and leaching with water the product so formed.

9. The -method of producing pulverous, oxidized carbon consisting essentially of submitting an anode of carbon that has been im-- product so, formed with water and with a solvent capable of extracting the moisture repellant. v

10. The method of producing pulverous, oxidized carbon consisting essentiallv of submitting an anode of carbon that has been impregnated with a moisture repellant to an electric current in a bath having an oxidizing oxy en containing anion and leaching the product so formed with water and benzol.

11. The method of producing pulverous, oxidized carbon consisting essentially of submitting an anode of carbonaceous material that has been impregnated with a moisture repellent to an electric current in a bath containing nitric acid.

12. The method of producing pulverous. oxidized carbon consisting essentially of submitting an anode of carbonaceous material that has been impregnated with a moisture repellant to an electric current in a bath containin nitric acid and sodium dichromate.

13. The method of producing oxidized carbon consisting essentially of submitting an anode of carbonaceous material that has been impregnated with paraffin to an electric current in a bath having an oxidizing oxygen containing anion and leaching the product so formed with water and benzol.

.145. The method of produ g oxidized carbon consisting essentially of submitting an anode of carbonaceous m terial impregnated with a moisture repellant to an electric current in a bath having an oxidizing oxygen gontiaining anion at a temperature. below .15. The method of producing oxidized carbon consisting essentially of submitting an "anode of carbonaceous material impregnated with a'moisture repellant to an electric current 1n a bath having.- an oxidizing oxygen ous form capable of passing through a 20 mesh screen and containing a moisture repella-nt. 10

In testimony whereof we aflix our signatures.

OLIVER W. STOREY. GORDON T. GOLLINSON.