Method for the preparation of carbon moldings and activated carbon moulding therefrom

Abstract

A method for the preparation of a porous carbon molding having a low apparent density, the method comprising the steps of thermally mixing a pitch, which has a softening point of 50° - 350° C, a carbon content of 80 - 97 wt%, a hydrogen/carbon ratio of 0.3-2.5 and a nitrobenzene-insoluble fraction of below 60 wt%, with at least one aromatic hydrocarbon having a boiling point of 200° C or higher, forming the mixture into a suitable shape, immersing the formed material in a solvent, in which the pitch is hardly soluble but the aromatic hydrocarbon is easily soluble, for extracting the aromatic hydrocarbon from the formed material and obtaining a porous pitch material, oxidizing the porous pitch material at a temperature from room temperature to 400° C by the use of an oxidizing agent to form an infusible porous pitch material, and calcining the infusible porous material in an inert atmosphere at a temperature higher than 600° C to obtain a porous carbon material. The porous carbon material or the infusible porous material may be activated by means of steam vapor or air to produce an activated carbon material.

We claim: 
     
       1. A method of converting pitch into a formed porous carbon material, including the steps of forming pitch into shapes, oxidizing the formed shapes at a temperature of room temperature to 400° C to make the pitch infusible, and carbonizing the infusibilized shaped pitch in an inert atmosphere at a temperature higher than 600° C, wherein the improvement comprises the combination of steps of: a. selecting a hydrocarbon pitch starting material having a softening point of 50°-350° C., a carbon content of 80-97, a hydrogen/carbon ratio of 0.3-2.5, and a nitrobenzene-insoluble fraction of less than 60%;   b. mixing said pitch starting material prior to said forming step with from 5 to 50 parts by weight of aromatic hydrocarbon per 100 parts of said pitch, said aromatic hydrocarbon being those having a boiling point of at least 200° C. and containing from 2 to 3 aromatic rings, said mixing being carried out with sufficient heating to form a fluidized mix which is subjected to said forming step to obtain said formed shapes; and   c. contacting the thus-produced formed shapes with a liquid organic solvent in which said aromatic hydrocarbon is soluble, said solvent being further characterized by the property that said pitch is substantially insoluble therein, said contacting extracting said aromatic hydrocarbon to increase the porosity of said formed shapes prior to said steps of oxidizing and carbonizing thereof.   
     
     
       2. The method of claim 1 wherein said pitch is formed into particles of spherical shape. 
     
     
       3. The method of claim 1 wherein said aromatic hydrocarbon is selected from the group consisting of naphthalene, methylnaphthalene, dimethylnaphthalene, anthracene, phenanthrene, triphenylene, diphenyl, diphenylmethane, and diphenylether. 
     
     
       4. The method of claim 1 wherein said solvent is selected from the group consisting of butane, pentane, hexane, heptane, methanol, ethanol, propanol, butanol, naphtha, and kerosene. 
     
     
       5. The method of claim 1 wherein said aromatic hydrocarbon is naphthalene and said solvent is methanol. 
     
     
       6. The method of claim 1 in which said aromatic hydrocarbon is naphthalene and said solvent is hexane. 
     
     
       7. The method of claim 1 in which said aromatic hydrocarbon is methylnaphthalene and said solvent is naphtha. 
     
     
       8. The method of claim 1 in which said aromatic hydrocarbon is phenanthrene and said solvent is heptane. 
     
     
       9. A method of converting pitch into a formed porous carbon material, including the steps of forming pitch into shapes, oxidizing the formed shapes at a temperature of room temperature to 400° C to make the pitch infusible, and carbonizing the infusibilized shaped pitch in an inert atmosphere at a temperature higher than 600° C, wherein the improvement comprises the combination of steps of: a. selecting a hydrocarbon pitch starting material having a softening point of 50°-350° C., a carbon content of 80-97, a hydrogen/carbon ratio of 0.3-2.5, and a nitrobenzene-insoluble fraction of less than 60%;   b. mixing said pitch starting material prior to said forming step with from 5 to 50 parts by weight of aromatic hydrocarbon per 100 parts of said pitch, said aromatic hydrocarbon being selected from the group consisting of naphthalene, methylnaphthalene, dimethylnaphthalene, anthracene, phenanthrene, triphenylene, diphenyl, diphenylmethane, and diphenylether, said mixing being carried out with sufficient heating to form a fluidized mix which is subjected to said forming step to obtain said formed shapes; and   c. contacting the thus-formed shapes with a liquid organic solvent in which said aromatic hydrocarbon is soluble and said pitch is substantially insoluble, said solvent being selected from the group consisting of butane, pentane, hexane, heptane, methanol, ethanol, propanol, butanol, naphtha, and kerosene, said contacting extracting said aromatic hydrocarbon to increase the porosity of said formed shapes prior to said steps of oxidizing and carbonizing thereof.   
     
     
       10. The method of claim 9 wherein said pitch is formed into particles of spherical shape.