US2339742A - Granulated active carbon from bituminous coal - Google Patents

Description

i -Mimic. 1944 UNITED STATES PATENT caries V I I 233a,?! NYE-ROM I I m'runmous cost Waiterin 1mm; State College, Pa.

No Drawing. Application January 24,, 1942;

' Serial No. 428,088

1 claim. 252-289) One of the obiects of my invention is to oxidize powdered bituminous coal without appreciable loss in weight but with complete destruction of cokingproperties.

Another object of my invention is to compress oxidized coal into bodies of small size, and any desired shape.

Another object of my invention is to activate compresed bodies of oxidized coal, thus producing a high-grade active carbon in granules of uniform activity.

Other objects of my invention are set iorth in the following description, it being understood that the above statement of the objects of my invention is intended to generally explain the same without limiting the same in any manner.

Likewise, Ido not wish to be limited to the specific examples which are later given herein as illustrating the best embodiments oi the invention, since numerous changes in procedure and in ingredients maybe made, without departing from the spirit of the invention Up to the present time, active carbon prepared from bituminous coal was interior to products obtained from other carbonaceous materials. However, high-grade active carbon may be produced from bituminous coal in good yield and I imiiorm. quality by due consideration oi the following:

(a) Three steps of manufacture-oxidation, shaping, and activation-must be coordinated.

(11) Optimum conditions must be established experimentally for each bituminous coal.

Oxidation as a step in the manufacture of active carbon from bitmninous coal has been considered by N. K. Chaney in U. S. Patent 1,499,908. He states that active carbon is only obtainable l by the activation of a so-called primary carbon,

which is defined as an active carbon base containing adsorbed hydrocarbons. Anthracite is regarded as native primary carbon. Bituminous coals may be similarly regarded although the hydrocarbons areusuailypresentin suchcoals in great execs of the adsorptive capacity of the active carbon base. and such excess may be readily removed by distillation under proper conditions.

The Chaney process calls for a primary carbon as starting material. In case of bituminous coal,

the primary carbon is prepared by distillation of the coal at temperatures not materially exceeding 500-600 C., with proper precautions to eliminate all of the bituminous matter of hydrocarbons which can be volatilimd at this temperature. If desired oxidising conditions may be maintained during the distillation, in order to minimize the proportion of adsorbed hydrocarbons in the residual active carbon base."

The oxidation ste adopted in the present invention differs from the Chaney process in that it calls for a treatment of comminuted bill! minous coal with air, preferably moist air at a temperature between 200 and 350 C. At this temperature no distillation of hydrocarbons and consequently no loss of carbon occur. This type of oxidation aims at complete destruction of coking properties by transformation of hydrocarbons into oxygen compounds such as acids, ketones, or the like.- Apart from, other advantages, the yield of active carbon is thus greatly increased.

The importance of activating a material 0! unlform particle size and density has been shown by various inventors (e. U. 8. Patent 1,753,801). In case or bituminous coahoxidized coal compressed into bodies oi small size provides the. desired uniform material for the final activation.

The application .01 the principles of this inventlon is illustrated by the following examples:

Erample 1.'A Central Pennsylvania bituminous coal with 22.0% volatile matter was grolmd to pass a 10 mesh screen. The comminuted coal was sent through a rotary furnace kept at 250 C;

at such a rate that the time of treatment did not exceed one hour. Oxidation was efleoted by sending a current of air saturated with water vapor at ordinary temperature through the furnace.

The oxidized coal was'mixed with 10 per cent water and compressed by means or a pellet press to pellets of i inch thicknes sand ,5 inch diam-' eter. The pellets were activated with steam between 800 and 900 C. The product is a highgrade granulated active carbon. I! desired it .maybe reduced in size and used'in' a finely divided or powdered condition.

Example 2.-A Central Pennsylvania bitlmik nous coal with 29.5% volatile matter was treated accordingto u. s. Patent'amam. m

ashfree oxidized product was compressed to pallets and activated as above. A high-grade ashfree granulated active carbon was obtained.

I claim:

A method of producing granulated active carbon from bitinninous coal which consists in oxidizing comminuated bitmninous coal at a temperature below 350' C. without subsmntial loss oi carbon until complete destruction or coking properties is accompliflied; mixing the oxidiad product with approximatehr IO-per cent'water: compressing the moist oxidized product into bodiesotsmallsizeandanydesiredshapaand activating the compressed bodies. K