US1456848A - Process for purifying anthracene press cake - Google Patents

Description

Patented May 29, 1923.

r Fete HARRY D. GIBBS, OF SAN FRANCISCO, CALIFORNIA, DEDICATED, BY MESNE ASSIGN- MENTS, TO THE PEOPLE OF THE UNITED STATES.

PROCESS FOR PURIFYING ANTHRACE'NE PRESS CAKE.

Ho Drawing.

Application flled February 8, 1919. Serial No. 275,904.

(FILED UNDER THE ACT OF MARCH 3, 1883, 22 STAT. I, 825.)

To all whom it may concern:

Be it known that I, HARRY D. GIBBS, a citizen of the Unitecll States of America and an employee of .the Department of Agriculture, residing in the city of San Francisco, county of San Francisco, State of California, have invented a new and useful Process for Purifying Anthracene Press Cake. This application is made under the act of March 3, 1883, chapter 143 (22 Stat. 625), and the invention herein described and! claimed may be used by the Government of the United States or any of its oflicers or employees in the prosecution of work for the Government or any person in the United States, without payment to me of any royalty thereon.

The object of my invention is to purify 0 anthracene, carbazole, phenanthrene and other useful compounds found in anthra cene press cake and separate them from each other in a higher degree of purity and; thus render these valuable compounds available in a sufiicient degree of purity for treatment in various chemical ways .to produce intermediate compounds and dyes from them.

The process of purifying anthracene, carbazole and phenanthrene has heretofore been carried out by means of solvents that dissolve one or more of the constituents more or less completely, thus enabling the separation by solution and! fractional crystallization. The process is slow, cumbersome and entails a considerable loss of valuable solvents. My process requires no solvents, is inexpensively operated and produces the desired substances in a higher state of purity.

In describing my process I shall, as an example, describe the several steps of the complete process, it being understood that while all of the steps are not independently novel they have not been heretofore employed in connection with the novel steps of the rocess, for which reason they have not satisfactorily accomplished the results attained in the practice of my invention.

It is well known that the constituents of For- Melting mula.

Boiling point.

Compound. p 01m Acenaphthene Phenanthrene. Acridine CuHln cHHlo CiaHnN CLSHIO CmHpN is lz 200 CisHi:

280 Above 360 {Above 360 Fluoranthrene 217 at 30 mm. pres. Fluorene 295 Pseudophenanthrene Above 360 Pyrene Above 360 213", also 360, also Anthracene given as 351 Carbazole Methylanthracene 3 Above 360 sens #48 the least volatile will separate out first. It

is also true that some of these constituents separate out in so fine a state of division that they are carried suspended in the air for a longer time than those constituents that are denser. This is well known.

I have discovered that when a current of air so charged with the substances is caused to move through small orifices the least volatile constituents separate and aggregate on the edges or against the orifices. Crystallization and separation from the vapor phase is thus assisted by theorifices and the passage of the gas through the orifices. These orifices may be arranged in large numbers in approximately the same plane in a sheet, plate or screen composed of metal, fiber or other substance, or the aggregation of orifices may be attained by use of gauze,

BI'S.

screen, cloth made of wire, or woven or spun anthracene press cake have lndividual meltfib .in warped or bent surfaces.

I have also found a multiple arrangement of these planes of orifices on the plan of connecting rooms or compartments offer the additional advantage of forming a temperature gradient varying from the highest temperature where the gas stream enters to the lowest temperature in the farthestcompartment, the fall in the temperature of the gases being quite sharp as they pass through the orifices or just after passing through the orifices. This temperature gradient between the compartments is caused by the removal of heat from the gases as they pass through the orifices by conduction and radiation.

1 do not wish to confine myself to the use of these orifices or screens in multiple in the same plane, but these orifices may be arranged in circles, in spheres, concentric or otherwise, or any figure of revolution or I have found that in various cases one arrangement possesses an advantage over other arrangements depending upon the character and state of the material which is being separated and also depending on the size and capacity desired in the apparatus.

I do not wish to confine myself to the use of atmospheric air for the reason that in some cases it is advisable to use furnace gases, flue gases, carbon dioxide or other gases.

The separation of carbazole may be facilitated, if desired, by taking advantage of the fact the carbazole is an amino acid and unites with metals to form salts. Very strong caustic soda or potash (sodium hydroxide or potassium hydroxide), or metallic sodium may be added to the press cake and melted with it. The sodium or potassium salt of carbazole is thus formed and this is not volatilized in the current of heated air. Since a compound of this nature is hydrolyzed by water given caustic alkali and carba-zole the air should be dried and every precaution taken to keep the amount of moisture present in the melt pot at a minimum. The salt of carbazole in the melt may be purified in various ways, preferably by neutralization with acid and subliming the carbazole.

An example of the working of this process with the use of alkali is given in the following figures compiled from a factory run and this may be regarded as embodying the essentials of the preferred procedure. However, I do not wish to be confined to this procedure for in very large scale operations various modifications will be necessary.

Anthracene press cake was mixed with 5 per cent caustic soda and heated in a closed iron vesel to 475 F. and a current of air run over it at the rate of 3 cubic feet fper minute for each square foot of screen sur ace separating the first compartment of the condenser from the secon The air current was conducted into the first compartment of the condensing apparatus consisting of a series of compartments separated from each other by screen made of wire cloth of about one-half inch mesh. The temperature of the gas stream entering the first compartment was about 200 C. and the temperature of this compartment should be maintained above 150 C., and preferably so high as 200 0., and in some cases to 250 C.

In large scale operations I consider it an advantage to'dispense with the use of alkali mixed with the press cake and feed the press cake molten into the moving air current where it may be distributed by means of bafiie plates.

The analysis of the anthracene press cake showed approximately 20 per cent anthracene, 25 per cent carbazole, 20 per cent oil and moisture, and the remainder the other constituents usually. present, principally phenanthrene.

The condensed material was collected from the various rooms and analyzed. The first and hottest compartment showed 43 per cent anthracene and 18 per cent carbazole, the middle compartments 25 per cent anthracene and 12 per cent carbazole, and the last or coolest compartment approximately 12 per cent anthracene, 8 per cent carbazole, and the remainder of the 100 per cent mostly phenanthrene.

A second treatment of the material from the first or hottest compartment without using caustic alkali to hold back the carbazole from subliming from the melting pot gave:

First compartment-carbazole 80 to 83%.

Second compartment-anthracene 75%.

Third compartment-almost all phenanthrene.

A third or a fourth treatment of the various fractions is advisable when further purification of the material 'is desired.

The quantities of material purified in a given time depend upon the size and arrangement of the apparatus, the volume of the air employed, and the character of the material.

The air current may be charged with the volatile constituents in various ways, other than described above, for example, by feeding the solid or molten material into the air stream or passing the air stream over or through bafiles containing the material to be volatilized.

The material collecting on the screen or around the orifices may be removed by shaking or jarring the screens, or by scrapers or brushes, operated by hand intermittently or continuously by mechanical devices.

The material falling from the screens and condensing in the various compartments may be removed from time to time by means of chutes in the bottom of the compartment or it may be scraped from the floor of the compartments and removed through doors placed in the side or bottom walls.

Having now fully described my invention, whatI claim and desire to protect by Letters Patent is 1. The process of purifying carbazole, anthracene and phenanthrene by fractional condensation from a moving gas stream, collecting these and other substances in compartments separated from each other by partitions containing a multiplicity of orifices of such size as not to act as a dust catcher. I

2. The process of purifying carbazole, anthracene and phenanthrene by fractional condensation from a moving gas stream, collecting these and other substances in compartments separated from each other by partitions composed of cloth with orifices of such size as to permit dust to pass there through freely.

3. A process of treating anthracene presscake, which comprises heating the same with an alkali to convert the carbazol present into a salt, then heating further to a temperature suflicient to fractionally sublime anthracene and other materials, and collecting such sublimed materials.

4. In the fractionation of crude anthracene press-cake, the steps of treating with an alkali, and thereafter heating to about 200 C. in contact with a flowing gas current, whereby substances other than carbazol are vaporized, and carried along by said gas current, and thereafter gradually cooling said gas current whereby such vaporized substances are deposited in the solid state.

5. The improvement in the recovery of methyl anthracene, phenanthrene and anthracene, which comprises heating to about 200 C. in a flowing gas current, a mixture comprising such materials, and gradually cooling the said gas current.

In testimony whereof, I aflix my signature in the presence of two subscribing witnesses.

HARRY D. GIBBS.

Witnesses:

COURTNEY CoNovER, L. A. SKINNER.