FI67527C - FOERFARANDE FOER FRAMSTAELLNING AV AKTIVKOL - Google Patents

Description

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Patent- och nghtantynlnn '' A — eimi ti ^ dod »utUfcrift—» p «Mtcmrmi 31.12.84 (32) (31) (31) Pyyd-ty« βοΟι ·· * · - * · «·« »priortuc 13- 07-78 Hungary-Hungary (HU) PE-1046 (71) Pdt? Nitrog £ nmuvek, Värpalota, Hungary-Hungary (HU) (72) Sändor Berkes, Szdkesfehdrvär, Jänos Jesztl, Veszpr £ m, B € la Szemes, Balatonalmädi, Gyula Kineses, Veszprdm,

Istvän Vig, Värpalota, Gäbor Hodossy, Veszpr £ m,

Lajos György Nagy, Budapest, L £ sz1 <5 Noszkö, Budapest,

Istvän Lakatos, Budapest, Gäbor Nemeshegyi, Budapest,

Antal Simai, Budapest, Gäbor Török, Budapest,

György Föti, Budapest, Hungary-Hungary (HU) (74) Berggren Oy Ab (54) Method for the production of activated carbon -Förfarande för framstäl1 Ning av aktivkol

The invention relates to a process for the production of activated carbon having a high specific surface area and a controlled pore size. The activated carbon produced according to the invention is primarily suitable for the treatment of waste water.

It is known that many chemical industry processes use activated carbon to remove by-products or treat accumulated wastewater. Due to increased environmental problems, most of the activated carbon produced is already used for this purpose everywhere. The advantages of this area of application must therefore be taken into account in the preparation of activated carbon.

When activated carbon is used for purification purposes, certain mixtures or groups of mixtures are adsorbed. This event is determined by the size of the adsorbing molecules or the pore size of the activated carbon. Choosing the right pore size is therefore very important; the effect of the cleaning operation or its economics depend on the correctly selected or prescribed i :.

67527 pore size. In addition, the particle size of the activated carbon is also an important factor in adsorption. The requirements for particle size vary depending on the technique or technology of the purification method used. Thus, for example, care must be taken to ensure a suitable particle size when the activated carbon floats in the liquid to be cleaned or when it has to precipitate within a certain time; particle size is also essential in so-called solid soil water towers, which require the use of particles whose structure remains unobstructed during use.

It is further known that the particle size of activated carbon can be adjusted in two ways: by mechanical treatment, for example by compression, and by a similar procedure in the production of activated carbon, so that the original particle sizes of the starting material used are preserved. It is therefore essential that the particle size can be controlled with as few work steps as possible or with as little work as possible and that it can be adjusted depending on the subsequent application.

There is a lot of professional literature on activated carbon manufacturing.

The most commonly used production method uses so-called chemical carbonating agents, for example zinc chloride, fuming sulfuric acid, sulfuric or phosphoric acid. The nature of this process is such that the carbonation of the starting material is carried out in the presence of an added carbonating agent. At the same time as carbonation, activation also follows. However, this method has several disadvantages: For example, the yield is small and when activated carbon is formed, the starting raw material changes greatly, it decomposes and crumbles. The low yield is primarily based on the fact that the chemical carbonator in a way decomposes the plant structure so that a considerable part of the carbon content evaporates as gaseous decomposition products.

Due to these shortcomings, activated carbon produced by chemical carbonation is also too expensive to be used to a greater extent for environmental protection purposes, such as wastewater treatment.

Another large group of known activated carbon production methods 67527 is a method based on thermal activation. However, such methods known so far can only be successfully implemented for a long time using very high temperatures.

The following are some concrete examples of each type of method.

U.S. Patent 3,840,476 describes the activation of liquid coke in two steps. In this process, the carbonaceous starting material is treated mainly with an oxygen-containing gas at 300-400 ° C and then with a gas containing 50% steam at 900-1100 ° C. The activated carbon produced by this method is suitable, as is apparent from the description of said publication, in particular for the binding of organic impurities in the effluents of oil refineries. A significant disadvantage of the method is the length of the activation time (about 7-20 hours). As stated by our own measurements, the specific surface area decreases greatly with the duration of activation.

U.S. Patent 3,755,193 discloses a method of making nitrogen-containing pulverized coal. In this method, the organic polymer is dissolved in a concentrated solution of an inorganic halide and thiocyanate, and the resulting sticky liquid is carbonized at 700-1200 ° C, the temperature being raised within a given temperature, suitably at a heating rate of 2-6 ° C per minute. The essential disadvantage of this method is that the heating rate is low and the activation therefore takes a long time.

Hungarian Patent Publication 165,759 describes a process for the preparation of activated carbon based on a slurry suspension obtained from organic matter. In this method, the slurry is first concentrated and then pyrolyzed in a reducing atmosphere. A significant disadvantage of this method is that the specific surface area of the product produced is small, namely only about 32 m / g.

Swiss patent publication 511 192 discloses a method for preparing an activated carbon-containing filtration mass based on a resinous wood material. In this method, resinous sawdust is treated with 3.6% (15-20 times by volume) sulfuric acid by weight and then distilled to dryness, after which additives such as tar, pitch and sugar or molasses are added to the resulting carbonization product and _ __ :: 1__ 67527 obtained the pulp is subjected to an ascending heat treatment at 450-500 ° C. The disadvantage of this method is that it is necessary to add 100-400% by weight of sugar or molasses, based on the weight of the carbonized substance, which makes the method very expensive and thorough.

Spanish Patent 426,440 describes a process for the production of activated carbon based on olive oil and oilcake. The starting material is purified by foaming and then carbonized in a nitrogen atmosphere at 700-900 ° C. At the same time, the product is activated with zinc chloride. However, this method has the great disadvantage that, on the one hand, high temperatures must be used for carbonation and, on the other hand, the zinc chloride used may cause environmental pollution and the method requires non-corroded equipment.

Polish Patent Publication 72,948 describes a continuous process for the production of charcoal. The starting material used is ligno-cellulosic wood, sawdust, chips or fruit seeds and thus not hydrolysed substances, in which case only low-quality activated carbon is obtained. Activation is performed in a monobasic retort in a water vapor atmosphere of 700-900 ° C. A similar method is described in German patent publication 737 332, the activation being carried out at 1000 ° C.

Furthermore, a German application 20 20 507 describes a method for producing activated carbon. Wastes from the acid fiber separation of xylose-containing plant materials are used as starting material. It is stated in the specification that the separation of the acid fiber is carried out with dilute inorganic acids at an elevated temperature and that zinc chloride or phosphoric acid is used as the chemical carbonating agent. However, this method has the considerable disadvantage that the inorganic acids used in the acidic fiber separation substantially degrade the plant structure, in addition to the above-mentioned major disadvantages associated with the use of zinc chloride or phosphoric acid as a chemical carbonating agent.

It is also an object of the invention to provide a continuously useful process for the production of activated carbon which -the size does not change significantly during the process, the carbon content of the starting material remains as completely as possible as activated carbon and despite which the volatile carbonaceous substances are still easy to handle in the form of volatile decomposition products.

The invention is based in part on the surprising finding that vegetable waste partially autocatalytically hydrolysed with an organic acid, in particular waste from the production of furfural, can advantageously be used as a starting material for the production of activated carbon. For example, it is known from Hungarian Patent Publication 164,886 that the partial steam hydrolysis of plant waste at 50-250 ° C and below 2 to 20 atmospheres takes place by means of organic acids remaining in the waste material and / or released from it, especially acetic acid and acetic acid. using autocatalyzed. The waste material thus obtained contains about 6-15% by weight of degradation products derived from cellulose and lignin, for example uric acids, saccharides and gallates, and the latter compounds are carbonized or caramelized even at a relatively low temperature (150 ° C). ). Organic acids obtained from partially hydrolyzed waste catalyze its cracking and thus increase the rate of reactions leading to carbonation. Thus, it is possible to carry out the carbonation without the use of carbonating agents and even at lower temperatures and in a shorter time.

The invention is further based on the surprising finding that a mixture of furfural, furfural resin intermediates and furfural resin in a weight of 10 to 15% by weight on the basis of the above hydrolysis of the starting plant waste material does not participate in said carbonization or caramelization. subject to. As already pointed out, the acid used in the above hydrolysis is present in the waste material used as a starting material, and under the action of this acid, a furfural resin is formed from said mixture of furfural, furfural resin intermediates and furfural resin. Therefore, the product does not crumble during the carbonation process, but its particles retain their original size due to the resin body formed.

___ ___________ L: _ 6 67527

However, both the described favorable carbonation event and the formation of the resin body only take place when the starting material is heat-treated at a temperature of 150-400 ° C at a heating rate of 10-40 ° C per minute, in particular 10-20 ° C / min and 400-600 ° C: at a temperature of so-called degassing, i.e. complete removal of volatile constituents, at a heating rate of 15-30 ° C per minute. The carbonation carried out according to the invention is effected by a heat treatment comprising 500-600 ° C and lasting up to 30 minutes, observing said heating parameter.

Furthermore, it has surprisingly been found that the desired particle sizes of the product can be obtained To temperatures of 1000 ° C.

The invention therefore relates to a process for the preparation of activated carbon from partially hydrolysed vegetable waste material by carbonating and activating it at high temperatures with at least one of steam, carbon dioxide and flue gas activators, wherein one or more activators that the partially hydrolysed vegetable waste material is an autocatalytically hydrolysed vegetable waste material which is indirectly or directly heated at 150-400 ° C, at a heating rate of 10-40 ° C per minute and at a heat treatment temperature of 400-600 ° C each selected 15 At a heating rate of -30 ° C per minute and heat treated at 500-600 ° C for up to 30 minutes and finally the activation is performed at higher temperatures for up to 30 minutes.

Preferably, the heating is performed at 150-400 ° C, at a heating rate of 10-20 ° C per minute.

It is further recommended that the heat treatment for 30 minutes be performed at a temperature of at least 550 ° C.

67527

Preferably, the activation is still to be performed at a temperature of 800-1000 ° C.

Heating to the activation temperature is conveniently performed at a heating rate of 10-20 ° C, preferably 16-20 ° C per minute.

Suitable organic acids for obtaining the hydrolysed vegetable waste material used as starting material in the process according to the invention are the organic acids contained in the waste material and / or released by decomposition from the waste material, in particular acetic acid and / or formic acid, in particular the former.

The main advantages of the method according to the invention are the following:

The pore size of the activated carbon produced according to the invention is, if necessary, predetermined or predetermined, has a large specific surface area and an excellent yield, so that there are no permanent disadvantages of the known methods carried out with strong inorganic acids. The method according to the invention can also be carried out continuously at low cost. The activated carbon produced according to the invention is therefore excellently suited for environmental protection purposes and its own production does not cause any environmental pollution.

In activation, the average particle size and pore volume or pore size distribution can be adjusted appropriately by selecting the parameters, depending on the area of use of the activated carbon to be produced in each batch. The pore size of the activated carbon produced by the process of the invention may increase to 5-1000 Å. To produce activated carbon with pores profitably of 5-100 Å, it is expedient to activate at 800-900 ° C for 3-5 minutes with steam or for 20-30 minutes with carbon dioxide or flue gas. It is also possible to mix said activators or to use them alternately.

To produce activated carbon with pores profitably of 100-1000 Å, the activation is expediently carried out at 900-1000 ° C for 20-30 minutes with carbon dioxide or flue gas or for 7-10 minutes with steam. Here, too, the various activators mentioned can be used mixed or alternately.

The starting point for the practical implementation of the method according to the invention is a suitably dried waste material. The grain size of this material most often rises to 0.2-20 mm and depends on the particle size of the starting material used for acid hydrolysis. Since the particle size of the starting material hardly changes in the process according to the invention, the particle size of the activated carbon produced falls substantially in this range.

The starting material for the process according to the invention is, for example, waste materials obtained by the process described in Hungarian Patent Publication 164,886 or "Escher-Wyss Mitteilungen" 1969 / 2-1970 / 1, pages 69-77, suitably waste from the manufacture of furfural and fodder yeast. Examples are wastes prepared from sawdust, maize cones, maize oilseeds, wood chips, rice husks, reeds or reed pressing waste by acidic autocatalytic hydrolysis.

When carrying out the method according to the invention, a starting material can also be considered to be moist, for example containing 5% moisture. In this case, in order to pre-dry the material, it is expedient to heat the initial temperature of the heating cycle of the heat treatment, i.e. 150 °, at a rate of 30 ° C per minute. Natural gas or flue gas from the combustion of decomposition waste from carbonation is appropriately used for heating as direct or indirect heating.

During carbonation, an inert gas, for example nitrogen, carbon dioxide or another oxygen-free or oxygen-poor gas (such as flue gas), can be passed directly or countercurrently through the reaction device containing the material to be carbonated, while at the same time flushing the decomposition waste from the remaining carbon.

Finally, it is expedient to cool the condensing part of the carbonation product obtained by carbonation, preferably with an acetone / carbon dioxide cooling mixture, and then to heat it to the activation temperature at which it is activated.

The invention is further illustrated by the following examples.

67527

Example 1

The pyrolysis tube was carbonized with 100 g of air-dry waste from the manufacture of furfural made from corn cob, raising the temperature to 200 ° C at a rate of 16 ° C, a range of 200-400 ° C at a rate of 10 ° C and a range of 400-600 ° C at 16 ° C: n minute speed. The temperature was then maintained at 600 ° C for 10 minutes and the material was carbonized. During this time, nitrogen was passed through the pyrolysis tube at a rate of 25 l per hour.

The resulting condensable decomposition products were cooled in a cooled separator connected to a pyrolysis tube with an acetone / carbon dioxide cooling mixture. After degassing, the tube was allowed to cool in the spent gas stream. The product was placed in a well-sealed container. There was thus obtained 36-41 g (36-41%) of the carbonation product.

The carbonization product was introduced in a pyrolysis tube at 16-20 ° C / min. at a heating rate of 900 ° C and activated at this temperature for 9-15 minutes while at this temperature water was introduced into the tube at an addition rate of 100 g per hour and the water vapor from the water was passed through the material using nitrogen as a towing gas at 25 l. h. After activation, the nitrogen stream was kept in the pyrolysis tube and allowed to cool to room temperature.

The product was sealed in a sealable container. Thus, 20.5-27 g of activated carbon were obtained, corresponding to 57-66% of the yield based on the carbonation product and 20.5-27% of the yield of the furfural production waste used as starting material.

The characteristics of the product were as follows:

Iodine value: 670-1000 mg J / g sample 3

Methylene blue: 3-7 cm methylene blue / 0.1 g sample.

Example 2

The pyrolysis tube was carbonized with 100 g of air-dry waste from the production of furfural starting from wood chips, raising the temperature to 200 ° C at a rate of 16 ° C per minute, a range of 200-400 ° C at a rate of 10 ° C per minute and a range of 400-550 ° C 16 ° C per minute. The material was then carbonized for 10 minutes at 550 ° C, passing carbon dioxide as an inert gas through the pyrolysis tube at a volume rate of 25 l / h.

The condensable decomposition products were cooled in a separator filled with acetone / carbon dioxide cooling to a pyrolysis tube. After degassing, the pyrolysis tube was allowed to cool to the temperature used for carbonation. The product was placed in a well-sealed container. There was thus obtained 36-37 g (36-37%) of the carbonation product. In a pyrolysis tube, 10 g of the obtained carbonation product was brought to a temperature of 850-950 ° C at a heating rate of 20 ° C per minute. This temperature was maintained for 15 minutes, at which time water was introduced into the tube at an rate of 30 g per hour and carbon dioxide at a volume rate of 25 l per hour. The water vapor used as the activator was transported through the pipe by the carbon dioxide acting as a towing device. After activation, the pyrolysis tube was allowed to cool under a nitrogen atmosphere.

The product was sealed in a sealable container. Thus, 7.1-7.3 g of activated carbon were obtained, corresponding to a yield of 71-73% based on the carbonation product and 26-27% yield based on the furfural production waste.

The characteristics of the product were as follows:

Iodine value: 500-6h0 mg J / g sample

Methylene blue number: 6-10 cm3 methylene blue / 0.1 g sample.

Claims (4)

11 67527 A process for the preparation of activated carbon from a partially hydrolysed vegetable waste material by carbonation and activation at high temperatures with an activating agent comprising steam, carbon dioxide and / or flue gas, wherein either one or a further known waste from the production of furfural is used, which is indirectly or directly heated to 150-400 ° C, a heating rate of 10-40 ° C per minute and 400-600 ° C, depending on the heat treatment temperature selected, at a heating rate of 15-30 ° C, and which is heat treated at a temperature of 500-600 ° C for a maximum of 30 minutes and finally activated at a maximum temperature for a maximum of 30 minutes. Process according to Claim 1 or 2, characterized in that the heating to 150 to 400 ° C is carried out at a heating rate of 10 to 20 ° C. Process according to Claims 1 to 3, characterized in that the heat treatment for at most 30 minutes is carried out at a temperature of at least 550 ° C. Process according to Claims 1 to 3, characterized in that the activation is carried out at a temperature of 800 to 1000 ° C.