DE2453325C2 - Process for the production of granular, chemically activated coal - Google Patents

Description

(a) ground solid carbonaceous raw material with an oxygen content of at least about 25% by weight (moisture-free and ash-free base),

(b) A binder which is soluble or emulsifiable in water and phosphoric acid solution, namely lignosulfonate and / or polyvinyl alcohol, in an amount that thereby at least 24 wt .-% of the total carbon, the mixture of a + b, and

(c) phosphoric acid in an amount that is a ratio of at least 035: 1, expressed as a ratio of 100% phosphoric acid to the dry mixture of a and b.

2. The method according to claim 1, characterized in that the carbonaceous raw material and the binder in the mixture can be proportioned to add to the starting mixture Carbon by the binder of at least 28% by weight and a ball abrasion hardness value of the To achieve end product of at least 90%.

The invention relates to a method for producing granular chemically activated carbon using a carbon-containing raw material mixed with phosphoric acid, molding the mixture and not in excess of temperature is heated to a approximately 65O ⁰ C, followed by washing the activated charcoal and is dried.

Activated charcoal is made commercially using either the steam or chemical activation process. The steam activation process is used when using raw materials that have been substantially or fully carbonized, either naturally as in the conversion of cellulosic materials into lignite and bituminous coal, or artificially by heating a carbonaceous raw material in carbonation retorts or furnaces in the absence of Air to temperatures of 600 ⁰ C.

Carbonizing the carbonaceous raw material decomposes the original carbon-hydrogen-oxygen compounds by expelling oxygen and gaseous compounds of carbon. Hydrogen and Oxygen: this is what makes the volatile content is reduced and the carbon content is increased. A carbonized raw material, which is used for economical Suitable for use in the steam activation process has an oxygen content of less than 25% on a moisture and ash free basis.

The pore structure that results from the carbonization allows the entry of water in the form of Steam. The controlled oxidation of the remaining carbon by steam at temperatures above approximately 700 ° C is the mechanism of steam activation. In practice the temperature is much higher. By means of this process, the carbonization created pore structure stretched and enlarged, so that a large surface area and a large Pore volume is generated within the particle.

When the carbonized raw material is soft like

for example charcoal, lignite or bituminous

Coal, produces the steam activation process

soft activated carbon product

When the carbonized raw material is hard, such as charcoal (based on coconut shawl) or Bituminous coal, which is ground and made into granular forms with pitch binders in order to increase their hardness, is produced the steam activation process produces a harder activated carbon product

Generally speaking, most gas phase and columnar liquid phase require users a hard, abrasion-resistant carbon with a ball abrasion hardness ("ball pan" hardness value) of at least 85, and preferably 90. In most cases, these requirements will come with a Coal, which is produced from hard, carbonized raw material with the help of the steam activation process has been

The chemical activation process, on the other hand, can be useful and economical only on raw materials which are not carbonized to a large extent. As its oxygen content and Hydrogen is reduced, one carbonaceous raw material becomes less by the chemical process activatable because the mechanism of the chemical process is selective and essentially complete Removal of oxygen and hydrogen as opposed to carbon by the chemical activator at temperatures below about 650 ° C, so that the carbonization takes place at the same time and activation.

In general, carbonaceous raw materials with an oxygen content of less than 25% and a hydrogen content of less than 25% and a hydrogen content of less than 5% are not suitable for use in the chemical activation process, as the amount activated is too small, to be economically useful. Suitable carbonaceous raw materials range from, for example Wood and Strou, which have an oxygen content of about 49% and a hydrogen content of about 6% on a moisture-free and ash-free basis, until, for example, common lignites, which contain oxygen and have hydrogen contents of at least about 25 and 5%, respectively.

In practice, the chemical activation process is limited to such carbonaceous raw materials which are sufficiently porous to allow easy absorption of chemical activator solutions in to allow an amount sufficient to simultaneously carbonize and activate the raw materials perform. Since materials of sufficient porosity are almost invariably soft, and since it is The chemical activation process is the almost invariable lack of sufficient porosity in hard materials limited in practice to soft carbonaceous raw materials; soft activated carbon

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l products were the end result. fuel content less than 60% and an oxygen

In US-PS 25 08 474 a chemical activity is greater than 30% on a moisture and ash-

Described rungsverfahren, which has the desire for free base and in water or in solutions

corresponds to a hard carbon product and evidently corresponds to the inorganic chemical activating agent.

Hardness values between 81 to 87 achieved. However, the 5 teaches is neither soluble nor emulsifiable, and which of the

This process does not require the use of binders, activating agents can be decomposed in such a way that they

and uses a relatively complex and expensive method, and essentially its oxygen and water

de with many process stages, such a process is removed without noticing the substance content

has not been used economically so far, as the co-carbon content has to be removed,

They are too high and the process is neither cost-effective nor efficient.

The method of quality activated with steam activated coal products is lignosulfonate.

can compete. Phosphoric acid is a chemical activating agent.

The cited publications therefore only describe the dependence on the level of activity, which borrowed chemical activation processes, deal with is desired, and whether the coal is for a gas or a The one who is versed is not required to do this with the creation of shaped or classy 15 liquid phase application Carbon bodies in which the hardness ratio of 100% phosphoric acid to carbonic acid is extremely high important in terms of the final dry-based materials at least one purpose of the process product. shirt 035: 1 for some gas phase coals and so big

The task on which the invention is based is approximately 135: 1, as is typical for chemically active

in creating a very hard, granular active 20 fourth powdered carbon for liquid phase

Coal product with improved abrasion resistance turn is applied.

and hardness. The invention asserts that by adding The mixing of the ground raw material, the binding

Mix together the ders specified in the main claim and the activating agent in a suitable one

Components taking into account the weight-related conventional manner results in a mixture with a

An activated charcoal product can be preserved within the central limits of its shelf life so that predetermined shapes are formed

th is that can be caused by an extraordinarily large, which the centrifugal effect of a

Characterized by hardness and a consistency that can be made into tablets withstands conventional rotary kilns. After this

mixing, the mixture is converted into the desired particle

This object is achieved according to the invention by bringing forms that are in the carbonization / Ak-

that a mixture of a, b and c 30 tivierungsofen are arranged as the starting mixture, where they are placed on a tem-

is used, whereby the following applies: temperature are heated that normally ^{does not exceed 650 0} C for a period of time which is less

(a) Ground solid carbonaceous raw material for less than 3 hours in a surrounding furnace atmosphere with an oxygen content of at least about This furnace atmosphere is defined as such, 25% by weight (moisture-free and ash-free base), 35 resulting from the essentially complete burning

(b) results in water and phosphoric acid solution soluble in or solution of natural gas or heating oil in a furnace,
emulsifiable binder, namely lignosulphonate The temperature and the duration of the carbonization / and / or polyvinyl alcohol, in an amount that activation heat treatment is accordingly at least 24 wt .-% of the total of the composition of the mixture and the carbon of the mixture of a + b 40 shafts varied which end in the activated carbon and product are desired.

(c) Phosphoric acid in an amount that a ratio can alternatively the surrounding furnace atmosphere of at least 035: 1 in terms of the ratio by supplying a carrier gas such as from 100% phosphoric acid to the drying air or steam can be modified to do just that a mixture of a and b, is formed. 45 Rinsing out the decomposition products of the carbonization

activation / activation heat treatment to accelerate

The carbonaceous raw material is advantageous. If steam is used as the flushing medium, it should

rial and the binder in the mixture is proportioned, no influence on possible steam activation

in order to add carbon to the mixture in the starting mixture, since the temperature

due to the binder of at least 28% by weight and 50 ren are too low for this reaction,

a ball abrasion hardness value of the final product of After the carbonization / activation treatment

to achieve at least 90%. the activated carbon particles are washed to

The carbonaceous raw material can be any solid to remove and recycle the amounts of phosphoric acid.

organic raw material, which is obtained primarily from coal, and then they are used in a conventional manner

substance, hydrogen and oxygen and little dried

at least 25 wt .-% oxygen to moisture and The surprising and completely unexpected

ash-free base and sufficient porosity. The result of this treatment is a highly activated carbon

has to the amount of chemical activation Ie in the desired shape and size, which is extremely hard

to absorb material that is necessary to make the material resistant and abrasion-resistant and in which the ball ab

rial through selective and essentially complete 60 hardness values of the particles range up to 97%.

Removal of its share of oxygen and water- The ball abrasion hardness refers to a standard

without noticeable removal of its carbon experiment, which is described in The American Society For Testing

to decompose substance content, so that a pore system in materials (ASTMK D 3802, is described. The Maie-

Within an amorphous carbon structure, rial is created in a vessel with a diameter

can be. 65 by 203 mm with 15 steel balls with a diameter of

The carbon-containing binding material can be 12.7 mm and 15 steel balls with a diameter of

be organic raw material, which primarily consists of Koh- 9.5 mm and arranged for a certain time

fuel. Hydrogen and oxygen is made up of a carbon treated. The weight in% of the molded samples that

are rubbed off is measured against the weight of the original sample.

Although it is not known what exactly will occur that causes this surprising effect, it is assumed that the raw material is impregnated by the activating agent and coated by the binder, while the latter is intimately mixed with the activating agent during the mixing stage. During the Heat treatment of the shaped particles of the mixture, the raw material is carbonized at the same time and activated, and the binding material is also similarly decomposed to possibly activate carbon bonds between the particles of the originally soft, to supply carbonaceous raw material. These re-formed, shaped, carbonized and activated Particles have a hardness and an abrasion resistance that are significantly higher than those values of the product by known processes in which the same carbonaceous raw material is used.

Experiments with activated charcoal, which with & ls the invention Process manufactured and intended for gas phase uses showed that they have a carbon tetrachloride adsorption activity greater than 95% and a ball abrasion hardness of almost 97% higher than most nut coals made by the steam process. Another activated charcoal produced by the method according to the invention and for liquid phase application had a molasses discoloration value of 90% and a ball abrasion hardness of almost 92%. Activated charcoal made from the same carbonaceous raw materials, the known one Method used which does not include binding material had a ball abrasion hardness in the range from 60 to 70%. Such a product is not economically competitive for most applications, a hard, abrasion-resistant, granular activated carbon is required

The results of these experiments show that very hard, shaped activated carbon particles by means of the process according to the invention from relatively soft, carbonaceous raw materials such as wood, Straw, peat and the like and similar carbonaceous materials can be produced, which comparable Have abilities to adsorb the chemical activating agent.

It has also been found that the hardness of the activated carbon is controlled within certain limits by proportioning the amount of the carbonaceous raw material and the carbonaceous one Binder in terms of the amount of coal, which in each case to the total carbon content of the mixture is. For example, if the carbon content of the binding material is approximately 24% of the Including total carbon content of the initial mixture is the ball abrasion hardness of the activated one Coal product about 85%. By increasing the addition of coal from the binder to approx 33% of the total carbon content in the initial mixture becomes the ball abrasion hardness of the activated one Coal product increased to 96%

The maximum content of the binder in the mixture is limited by economic considerations, since the carbon content of the binder is more expensive than that of the preferred carbonaceous raw materials, and by the fact that hardness values above about 97% disproportionately large increases in the

Require proportion of binding material.

While lower amounts of binder the ball abrasion hardness of the activated carbon is significantly opposite known processes, a granular activated carbon must have a hardness of at least 85% have to compete with steam activated coal made from hard carbonized raw materials in most gas and columnar liquid phase applications.

With the invention, a chemical activation process is thus created, which with the steam activation process is competitive

Prior to the invention, despite the advantages of chemical activation in terms of higher yields, greater had Control of pore structure and lower capital costs chemically activated granular coal only a relatively small market share. According to the invention, a method for the production of granular, chemically activated charcoal, at least of the same quality and in many respects νοη desirable Properties created as the coal, by means of known chemical or steam activation processes is produced.

The invention is illustrated below using examples

Example I.

10 parts of ground wood were mixed with 3 parts of ammonium lignosulfonate and 13 parts of 85% phosphoric acid. The ingredients were ^; Extruded in tablet form and then ^{carbonized / activated in a rotary kiln at 500 °} C. for 75 minutes. The molded tablets were strong enough to withstand agitation in the rotary kiln. After emptying from the oven, the tablets were washed in hot water to recover the phosphoric acid and then dried. The resulting activated carbon tablets had a carbon tetrachloride etching activity of 69% and a ball abrasion hardness of approximately 85%.

Example II

10 parts of ground wood were mixed with 73 parts of a 50% ammonium lignosulfonate solution and 7.5 parts of a 75% phosphoric acid. The mixture was extruded in tablet form and then carbonized / activated ^{at 550 ° C. for 120 minutes}

The activated charcoal thus obtained had a carbon tetrachloride activity of 60%, an iodine activity of 79%, and a ball abrasion hardness of 90%.

Example III

10 parts of wood flour were mixed with 9.25 parts of a 50% ammonium lignosulfonate solution and 6.65 parts a 75% phosphoric acid mixed. The tablets extruded from the mixture were during Carbonized / activated for 90 minutes at a temperature of 575 ° C. The activated coal produced had a carbon tetrachloride activity of 67% and a Ball abrasion hardness of 95%.

Example IV

10 parts of wood flour were mixed with 2 parts of ammonium lignosulfonate solids, 6 parts of piner 50% am-

monium lignosulfonate solution and 17.3 parts of an 85% phosphoric acid mixed. The tablets extruded from the mixture were carbonized / activated at a temperature of 525 ° C. for 110 minutes. The activated carbon product had a carbon tetrachloride activity of 96%, a surface area of 1300 m ² / g, and a ball abrasion hardness of 97%.

Example V

10 parts of sawdust were mixed with 3.2 parts of polyvinyl alcohol and 173 parts of a 1% phosphoric acid mixed. The tablets extruded from the mixture were heated to a temperature of is for 100 minutes. 550 ° C carbonized / activated. The manufactured activated Coal had a carbon tetrachloride activity of 90% and a ball abrasion hardness of approximately 91%.

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Claims (1)

Patent claims: 1. A process for the production of granular, chemically activated charcoal by a carbonaceous raw material mixed with phosphoric acid, the mixture is formed and ^{heated to a temperature not exceeding about 650 0} C and then the activated charcoal is washed and dried, characterized in that a mixture of (a, b) and (c) is used as the starting mixture, where: