USRE16896E - Bonding activated carbon - Google Patents

Description

UNITED. STATES an'rnun n. RAY, orravs'rnn; nnw YORK, assronon 'ro caianrnn m cannon PATENT orrlca.

OHEHICALS CORPORATION, A CORPORATION 01 NEW YORK.

BONDING ACTIVATED CARBON.

Io Drawing. Original No. 1,565,828, dated December 15, 1925, Serial 1T0. 511,171, filed October 28, 1981. Application fon'reissue filed September 7, 1927. Serial No. 218,105.

. This invention relates to porous materials suitable for use in the treatment of fluids and to processes of. preparing such.

materials. More specifically, the invention 6 involves the provision of'a ri id porous mass adapted for use in the purification and storage of gases and for other purposes.

One'of the principal objects of the invention is to provide an improved filling for 1 receptacles intended for the storage and transportation of dissolved acetylene.

It has heretofore been proposed to utilize porous materials, with or without binding agents, for the purposes above mentioned.

Fragmentary material is objectionable because of its tendency to settle, and, so far as I am aware, most of the binders pre-. viously suggested have been non-absorptive and in many cases subject to deterioration in .the connection in which they are used. In distinction to. this, products prepared according to my invention are rigid, inert and characterized by absorptive capacity in both the fragmentary material and the binding agent. Generally speaking, such products consist of an aggregate of fragments of porous absorbent material cemented together by a coherent carbonaceous residue which is also porous and absorbent.

In some cases, however, non-carbonaceous binders may'be used, and a typical example of such use will be describedhereinafter.

A preferred method of forming the carbon-bonded absorbent mass is first to mix the fragments of absorbent material with a decomposable substance capable of giving a coherent and adherent carbonaceous residue on decomposition and then to decompose the. substance so that its carbonaceous residue will firmly bind together the absorbent fragments. The materials usedmay be so chosen that the final product will be strong and capable of withstanding shocks of considerable violence and yet will be highly porous.

The absorbent fragments in the agglomierate may advantageously consist of charcoal, In this case, the binding mat'erial'and the bound particles will be of similar composition but vwill differ in origin. Ordinary charcoal may be used or the fragments tobe agglomerated may be formed 111 a predesirable that the carbonaceous material should be in a liquid state at some time before it is fully decomposed. This is accomplished by using a solution, or b using a fusible decomposable substance. f course, a fusible substance in solution may be used.

As organic compounds for producing the bonding carbon, carbohydrates have many advantages. These substances usually fuse before or during thermal decomposition and are generally quite soluble in water. Sugars,

especially the cheap and very soluble sugars,

are satisfactory carbohydrates. Bituminous and resinous materials may be used insome cases for producing the bonding carbon.

When charcoal is used as the fragmentary -material, any grade ofreasonable'porositymay be selected and bonded with a carbonaceous material of the type above indicated. For example, charcoal fragments may be stirred into a; concentrated sugar solution until a pasty mass is obtained and this may be sub ected to heat in a suitable container provided with a vent for the water vapor and gases expelled during the decomposition of the binder. It is preferred to raise the heat by stages to a point somewhat above the temperature at which the sugar completely decomposes. is strongly coherent and has satisfactory absorptive capacity: I

In order to provide a mass of especially high porosity, I follow the-procedure now to be outlined, selecting as the porous material a highly absorptive charcoal, or in the The resulting mass 7 'erably reduced during the process free from extractable matter, is crushed to such fineness that it will pass a six mesh screen and stay on a 100 mesh s breen. Cane sugar is mixed with the charcoal fragments in theproportion of about three parts by wei ht of sugar to two parts of charcoal. Pre erably the sugar is made into a syrup with water before mixing it with the charcoal. The mixture is plastic at this stage and is packed tightly by bumping and tampingfnto the containers in which the sugar is to e decomposed. The containers are closed with the exception of one or more small outlets for gases and are subjected to heat, the temperature being increased at the rate of 0. per hour until 450 C. is attained, this temperature being continued for about four hours. B mixture, this is first expelled and the sugar remains in'molten stage. At a higher temperature the molten su ar begins to decompose and the gases evo ved by its decomposition will cause thematerial to completely fill the receptacle. As the sugar tends to increase in volume during decomposition, no objectionable cavities are formed in the mass. The carbonaceous residue of the sugar strongly binds the charcoal fragments tother and is highly porous, while the porosity of the charcoal articles isnotcon i iilie resulting mass has suificient mechanical strength to resist crushing under considerable compressive force. Glucose and other sugars may be used instead of cane sugar,

either with or without tlie addition of water.

In the form of the invention which I now regard'as preferable, the material known'as activated carbon is substituted for the charcoal employed in the specific example given above. Activated-carbon may be preared from charcoal or from a denser carnaceous material, such as bituminous or anthracite coal. It differs from what is commonly referred to as charcoal in that at has an adsor tive capacity of higher and entirely di erent order, due to the-fact that it I is sgepared from a material having an actlve orptive) carbon base, this base being substa'ntiall freed from absorbed hydrocarbons by di erential oxidation during the activating process.

Activated carbon and processes of making If water has been used in the.

mace

it are described in detail in, United States patent to Newcomb K. Chaney No. 1,49:T,543,

In baking the mass to which the binder has been added, the procedure should be such that the absorptive properties of the carbon are not destroyed by cloggingit with hydrocarbons or inactive carbon. The binder and baking schedule mentioned in the specific example are suitable for preserving the adsorptive capacity of the carbon. Because of its greater porosity, activated carbon prepared from hlghl porous materials, such as charcoal, is pre erable for producing an absorbent mass.

When the mass is designed as a filling material for acetylene cylinders, it may be formed into blocks in suitable molds and these blocks then packed in a storage tank in the same manner that porous blocks have heretofore been packed in such vessels. However, I prefer to form the mass directly in the acetylene storage tank as this is simpler and insures complete freedom from objectionable cavities. The tanks are not juriously affected by the temperatures used in the baking operation.

When used,- as a filling mass for acetylene cylinders the material prepared in accordance with the above has im ortant advan-. tages. Its strength and rigidity prevent the formation of o jectionable cavities during the filling, testin and discharging operations or by the s ocks incidental to transportation anduse, even after long periods of time. The entire mass is essentially carbon and is therefore non-reactive toward all acetylene solvents, and is capable-of withstanding high temperatures without decomposition or volatihzation of any of its constituents.

While in the preferred form of my invention fragmentary activated carbon is bonded with carbonaceous material, good results may be obtained by the use of other binders. The absorptive capacity of activated carbon is so great that this property in the bonding material need not be of a high order, and

the invention includesthe bonding of activated carbon with any agglomerated material not substantially diminishin tivity. For example, satisfactory llers for acetylene storage cylinders may be prepared by mixing activated carbon particles with cement of the type of Portland cement, adding water and allowing the mass to set. The composition may be molded into the desired shape or may be placed in the cylinder while plastic. Suitable materials, such as kiesel uhr and fibrous asbestos, may be mixed with the absorptive carbon- 1. A process-of bonding activated carbon its 110- which comprises associat' such carbon bon with a carbohydrate and applying reguwith a sugar and thermal y decomposing lated he at to decompose said carbohydrate said sugar to give a carbonaceous bonding without substantially impairing the activity 10 a residue. of said carbon.

l 2. Aproc'ess of formingacoherent massof In testimony whereof, I afiix my signaactivated carbon which comprises mixing ture. I an aggregate of fragments of activated carv ARTHUR B. RAY.