EP3927881A2

EP3927881A2 - Method for reducing the odour in particle-forming carbon materials

Info

Publication number: EP3927881A2
Application number: EP20759929.1A
Authority: EP
Inventors: Tobias Wittmann; Jacob Podschun; Gerd Schmaucks; Ulf LÜDER
Original assignee: Suncoal Industries GmbH
Current assignee: Suncoal Industries GmbH
Priority date: 2019-02-21
Filing date: 2020-02-21
Publication date: 2021-12-29
Also published as: CN113498424A; CA3131170A1; KR20210132058A; JP2022531753A; WO2020169809A2; WO2020169809A3; CL2021002011A1; MX2021010141A; US20220135408A1

Abstract

The invention relates to a method for reducing the odour in particle-forming carbon materials and to the materials obtained therefrom and to the use thereof.

Description

Process for reducing the odor of particulate carbon materials

The present invention relates to a method for odor reduction of particulate carbon materials and the materials obtained therewith and their use.

State of the art

[0002] Particulate carbon materials are used in many fields of application. These range from use as a black dye to use as a filler in polymers, for example elastomers, thermoplastics or thermoplastic elastomers. Such carbon-based materials can be, for example, soot, materials with a relatively high proportion of carbon. Other particulate carbon materials are obtained from renewable raw materials. Such particulate carbon materials have a somewhat lower proportion of carbon compared with carbon black, but show interesting properties due to a high degree of functionalization. Particularly interesting starting materials for the production of particulate carbon materials based on renewable raw materials are starting materials that can be completely or partially dissolved, for example sugar, starch or lignin. Such starting materials, which are wholly or partly in solution and based on renewable raw materials, can be converted into particulate carbon materials by precipitation processes. Precipitation processes for the production of particulate carbon materials in solution are sufficiently known to the person skilled in the art.

For example, a lignin-based particulate carbon material can be obtained from lignin which is dissolved in a base, for example sodium hydroxide solution, by precipitation by introducing an acidic gas such as CO 2 or H 2 S or by adding an acid H 2 SO 4. Examples of this prior art are given in W02006031175, W02006038863 or W02009104995.

Furthermore, a lignin-based particulate carbon material can be obtained from lignin, which is dissolved in a base, for example sodium hydroxide solution, by increasing the temperature to, for example, conditions of hydrothermal carbonization by precipitation with simultaneous stabilization. Examples of this prior art are described in WO 2016/020383 or WO 2017/085278 Processes for precipitation by introducing an acidic gas, by adding an acid or by increasing the temperature can also be combined with one another.

In the production of particulate carbon materials, the adjustment of certain process parameters opens up the influence in particular of the grain sizes to be obtained (i.e. the size of the agglomerates to be obtained, which are composed of primary particles), as well as the setting of surface parameters, in particular the specific surface area, which also is used as a measure of the primary particle size. This can be quantified, for example, using methods for determining the surface, such as BET determinations or STSA determinations. The sum of the outer and inner surface is determined by a BET measurement, while only the outer surface is determined in an STSA determination. Suitable determination methods are given, for example, in ASTM D 6556-14.

It is known that the average size of the primary particles or the height of the specific surface area has an influence on the properties of the materials produced using the particulate carbon materials, for example rubber articles produced by compounding the particulate carbon material with elastomers with subsequent crosslinking . For example, the abrasion behavior of a rubber article is different depending on whether particulate carbon materials with a higher or lower BET surface area are used. The same applies to mechanical properties, such as tensile strength. Higher values for the BET surface area correlate with higher tensile strength values and lower abrasion. When using particulate carbon materials, values for the specific surface area of at least 5 m ² / g, preferably at least 8 m ² / g, more preferably at least 10 m ² / g, furthermore preferably at least 15 m ² / g or more are required, to get high quality rubber items.

However, a disadvantage of the known particulate carbon materials obtained, for example, by precipitation of completely or partially dissolved starting materials based on renewable raw materials, in particular lignin-based particulate carbon materials, is the unpleasant odor that emanates from the particulate carbon material itself when processing the particulate Carbon material is released and / or emanates from the materials contained in the particulate carbon material. This severely limits the possible uses of the particulate carbon materials, which are of great interest. Methods for reducing the odor of lignin-based particulate carbon materials are known in the art. These rely on the one hand on the pre-cleaning of the lignin, for example by extraction processes (WO2013 / 101397), enzymatically catalyzed reactions (DE 10 2006 057566), treatment with oxidizing components with subsequent washing (DE 10 1013 001678), on the other hand on the treatment of, for example Black liquor, through evaporation processes, treatment with reducing agents or oxidizing agents or chlorination reactions as well as high-temperature treatments. However, such processes require the treatment of relatively large amounts of substance or require the use of chemicals, which is disadvantageous in terms of both equipment and financial expenditure.

It would therefore be desirable to be able to provide a method that a targeted reduction of the odor which emanates from the particulate carbon material itself is released during the processing of the particulate carbon material and / or emanates from the materials containing the particulate carbon material without the use of other materials Process chemicals made possible, preferably by treating the particulate carbon material already obtained. In this way, costs and equipment expenditure can be reduced, while at the same time the amount of material to be processed is lower. Another requirement of such a method is, however, that the treatment to reduce odor does not lose the desired properties of the particulate carbon material, such as the specific surface area, for example.

Also, the loss of material should not be too high, since the particulate carbon material is already a valuable product.

Object of the invention

[0010] It is therefore the object of the present invention to specify such a method in order to provide the particulate carbon materials described above.

Brief description of the invention

This object is achieved by the method defined in claim 1 and the product defined in claim 7, as well as the use defined in claim 10. Preferred refinements and further aspects of the present invention result from the embodiments specified in the further claims and the following detailed description. Brief description of the figures

FIG. 1 shows schematically a possible temperature profile for an example of a method according to the invention

FIG. 2 shows BET surface areas of the starting materials and of the thermally treated particulate carbon materials of the invention as a function of the maximum temperature reached during the treatment.

FIG. 3 and FIG. 4 show pictures of the surface properties of pressureless vulcanized elastomer compounds, produced with a particulate carbon material, before and after carrying out the method of the present invention.

Detailed description of the invention

The method of the present invention allows the simple odor reduction of particulate carbon materials produced from starting materials based on renewable raw materials.

A characteristic of the method according to the invention is, for example, that a particulate carbon material (hereinafter referred to as pKM) is obtained in a first process step, the odor of which is reduced in a second process step, whereby the odor-reduced pKM is obtained. This pKM can, for example, be a precipitated lignin, but preference is given to pKM, in particular lignin-based, which have also been subjected to hydrothermal carbonization.

[0014] The starting material can preferably be completely or partially dissolved in a liquid. More preferably, the starting material consists of more than 50% sugars, starches or lignin.

Preferred embodiments of the first process step are described below. In the context of the present invention, it is not relevant whether this first process step is carried out directly before the second process step or whether this first step takes place well before the second (so that, for example, the pKM from the first step is produced separately and then stored, before it is subjected to the second step). The pKm is preferably obtained in the first process step by precipitating a completely or partially dissolved starting material. If the starting material consists of more than 50% lignin, the pKM is preferably obtained by precipitating lignin completely or partially dissolved in a liquid by introducing an acidic gas and / or by adding an acid and / or by precipitation and simultaneous stabilization under conditions of a hydrothermal carbonization (HTC).

Such processes are known to the person skilled in the art and are described in WO2006031 175 or WO2006038863 or WO2009104995 (precipitation) or WO2016 / 020383 or WO2017 / 085278 (precipitation and simultaneous stabilization).

It has proven to be expedient if the pKM after the first process step has a BET surface area of at least 5 m ² / g, preferably at least 8 m ² / g, more preferably at least 10 m ² / g, furthermore preferably at least 15 m ² / g or more. The BET surface area is advantageously a maximum of 200 m ² / g, preferably a maximum of 180 m ² / g.

The BET surface area of the pKM advantageously only deviates from its STSA surface by a maximum of 20%, preferably by a maximum of 15%, more preferably by a maximum of 10%. The pKM is therefore preferably not porous.

The pKM also preferably shows a carbon content (based on the ash-free dry substance) of 50 to 80% by mass (% by mass), more preferably 60 to less than 80% by mass. The pKM is thus a material that differs from carbon black in terms of its carbon content. Due to the preferred production of the pKM by precipitation or precipitation in combination with a stabilization (such as an HTC), the lower carbon content in comparison with carbon black ensures at the same time that a high content of functional groups is present on the particles. These can be advantageous for the subsequent use of the pKM.

In the following, preferred embodiments of the second process step are described:

According to the invention, the pKM is converted into the odor-reduced pKM in the second process step in a gas atmosphere. Advantageously, the second process step does not take place under atmospheric air, but under a process atmosphere. The process atmosphere is understood to mean, for example,

an air enriched with inert gases which has an oxygen content of less than 15% by volume, preferably less than 10% by volume, more preferably less than 5% by volume, particularly preferably less than 3% by volume, and or

an air reduced in pressure with a pressure of less than 500 mbar, preferably less than 200 mbar, more preferably less than 100 mbar.

The oxygen content of a process atmosphere consisting of air enriched with inert gas is advantageously at least 0.1% by volume, preferably at least 0.5% by volume, particularly preferably at least 1% by volume.

A suitable inert gas for the purposes of the present invention is in particular nitrogen, carbon dioxide, superheated steam or gases released from the pKM during the second process step. Although the gas released from the pKM during the second process step also contains, for example, carbon monoxide, hydrogen, etc., it is referred to in this document as inert gas. When using air enriched by means of an inert gas as the process atmosphere, the pressure can, as already stated above, be selected depending on the possibilities or requirements. The simplest apparatus is to conduct the process at ambient pressure or only slightly negative or positive pressure, for example at + -10 mbar.

The second process step is preferably controlled (for example by selecting the temperature profile, the maximum temperature, the process atmosphere, possibly the selection of the pressure) that the mass loss of the pKM in the second process step is less than 20%, preferably less than 15% , more preferably 10% or less. A certain loss of mass is necessary during the second process step of the method according to the invention in order to reduce the content of odorous substances. This mass loss will usually be at least 1% or more, preferably at least 2% or more, in some cases 5% or more. This ensures and achieves that not too much material is lost and, on the other hand, that the desired odor reduction is achieved. In this way, the suitability of the treated pKM for use as a filler, for example in elastomers, can be ensured. Regardless of the selection of the process atmosphere of the second process step, the process temperature in the second process step should exceed a minimum temperature and not exceed a maximum temperature. The maximum temperature is 300 ° C, preferably 250 ° C or less, more preferably 230 ° C or less. The minimum temperature is 150 ° C, preferably 160 ° C, more preferably 170 ° C, in some cases 180 ° C. The holding time during which the pKM is held in the process atmosphere at the process temperature in the second process step can be selected over a wide range. Suitable values are 1 second and more and 5 hours or less. The holding time is preferably 60 minutes or less, more preferably 30 minutes or less, particularly preferably 15 minutes or less, in some cases less than 10 minutes.

The process temperature of the second process step is preferably chosen so that it is a maximum of 50 ° C, preferably a maximum of 40 ° C, more preferably a maximum of 30 ° C, particularly preferably a maximum of 20 ° C, in particular a maximum of 10 ° C above one

Further processing temperature and / or usage temperature, however, is not below the minimum temperature and not above the maximum temperature.

The process temperature of the second process step is preferably chosen so that it is at least 50 ° C., preferably at least 40 ° C., more preferably at least 30 ° C., particularly preferably at least 20 ° C., in particular at least 10 ° C. below one

Further processing temperature and / or usage temperature is.

The further processing temperature is the temperature at which the odor-reduced pKM is processed into a product in a mixture with other materials. If the odor-reduced pKM is incorporated into rubber mixtures, for example, the further processing temperature means, for example, the temperature at which the rubber mixture is crosslinked, for example a temperature between 150 ° C and 180 ° C when using sulfur crosslinking.

The usage temperature means the temperature at which the product containing the odor-reduced pKM is used. If the odor-reduced pKM is used, for example, in an EPDM-based product, the usage temperature is, for example, a maximum of 150 ° C. If the odor-reduced pKM is used, for example, in an FKM-based product, the usage temperature is, for example, a maximum of 250 ° C.

If the further processing temperature and / or the use temperature is below the temperature of the first process step, the process temperature is preferably not above, more preferably below, particularly preferably at least 1 ° C. below, furthermore preferably at least 5 ° C. below the temperature of the first process step.

In a preferred embodiment, a lignin-based starting material is stabilized in the first process step under conditions of hydrothermal carbonization and, in the second process step, the temperature of the stabilization under conditions of hydrothermal carbonization is preferably not exceeded, more preferably not reached, particularly preferably by at least 1 ° C fallen below, more preferably at least 5 ° C below.

It has been found to be advantageous that the pKM is not only treated in the second process step during the holding time under the process atmosphere, but also the heating and cooling takes place under the process atmosphere.

An essential point for improving the second process step is the combination of heating rate and process temperature. The cooling rate, however, can be chosen freely. The pKM is preferably only heated to the process temperature above a critical temperature in a controlled manner. Until the critical temperature is reached, the speed of heating can be freely selected (i.e. here, for example, heating can take place very quickly). From the critical temperature, however, it is important that the heating rate is controlled. It has been shown that in the event of uncontrolled heating above the critical temperature, disadvantageous effects occur, in particular an undesirably high loss of mass and a large loss of BET surface area. Heating rates from the critical temperature of less than 30.degree. C./min, in particular 20.degree. C./min or less, have proven to be particularly advantageous. Preferred ranges for heating rates are in the range from 1 ° C / min to 20 ° C / min, such as 5 ° C / min to 10 ° C / min. If the maximum temperature of the treatment is 250 ° or higher, it has proven to be preferred if the heating rates in this temperature range are particularly low, such as 0.1 ° C./min to 5 ° C./min.

The critical temperature differs depending on which starting material was converted into a pKM in the first process step and how the first process step is designed. The critical temperature is usually between 80 ° C and 250 ° C, more preferably between 100 ° C and 230 ° C.

Was the pKM in the first process step, for example, by precipitation with combined stabilization under conditions of hydrothermal carbonization from softwood lignin obtained, the critical temperature in the second process step is preferably between 150 ° C and 230 ° C, more preferably between 180 ° C and 220 ° C.

If the pKM was obtained from hardwood lignin in the first process step, for example by precipitation with combined stabilization under conditions of hydrothermal carbonization, the critical temperature in the second process step is preferably between 130 ° C and 200 ° C, more preferably between 140 ° C and 180 ° C.

If the pKM was obtained from softwood lignin in the first process step, for example by precipitation with combined stabilization under conditions of hydrothermal carbonization, a mass loss of only 10% or less can be achieved with a second process step, for example at a maximum treatment temperature of 250 ° C. or less , with a simultaneous loss of BET surface area of about 5 m ² / g or less (if the pKM has a BET surface area of 40 m ² / g, this falls to a maximum of 35 m ² / g). At the same time, odor tests show a significant decrease in unpleasant odor development. This waste was found on the odor-reduced pKM itself, during the production of a rubber article which was filled with the odor-reduced pKM, and also on the rubber article in comparison to one with a pKM that had not passed through the second process step.

The method according to the invention can thus achieve a good balance between the desired minimization of odors and, at the same time, extensive retention of the desired material properties and a low loss of mass. Neither the use of process chemicals nor complex procedures are necessary. The maximum temperature of the treatment according to the invention is also in a comparatively low range, which is advantageous both in terms of costs and in terms of process control.

Devices for performing such treatments are well known to those skilled in the art. The second process step is preferably carried out in a rotary kiln or a fluidized bed. The second process step can more preferably be combined with grinding or sifting, for example in a gas jet mill, in a turbo-rotor mill or an air classifier.

As already described above, the pKM obtained according to the invention, preferably based on lignin and preferably obtained by a precipitation or a precipitation with combined stabilization, for example under conditions of hydrothermal carbonization, are also proposed for use in rubber mixtures. As part of the The present invention has shown that odor-reduced PCMs produced according to the invention are particularly suitable for use in elastomer compounds in which the desired rubber articles are produced by pressureless vulcanization. Here, rubber articles which contain pKM which was produced according to the prior art, in addition to the odor development during vulcanization and the odor of the vulcanizate obtained, exhibit an undesirable porosity, which significantly reduces the mechanical properties. Here the method according to the invention makes it possible to overcome this disadvantage. While the development of odor could possibly be reduced to acceptable values by storage for a limited period of time after product manufacture, a product impaired by porosity is fundamentally not acceptable. This can also be avoided within the scope of the present invention.

In the context of the present invention it has also been shown that odor-reduced pKMs produced according to the invention are also changed in polarity or hydrophobicity and, for example, are more compatible for use in hydrophobic or less polar elastomer compounds than pKMs produced according to the prior art.

The odor-reduced particulate carbon material is advantageously obtained by the method described above. The present invention thus also provides an odor-reduced pKM, preferably obtained by the method according to the invention.

The odor-reduced pKM differs from materials according to the state of the art, for example, in that

that it has a BET of at least 5 m ² / g,

the odor of a rubber article produced using 50 phr of reduced odor pKM is more comparable to the odor of a rubber article which was produced using 50 phr N550 than to the odor of a rubber article which was produced using 50 phr LignoBoost Lignin.

The odor-reduced pKM preferably has a proportion of dimethyl sulfide of a maximum of 1 mg / kg, preferably of a maximum of 0.5 mg / kg, more preferably less than 0.1 mg / kg, furthermore preferably less than 0.05 mg / kg in particular less than 0.01 mg / kg. The odor-reduced pKM preferably has a guaiacol content of at most 0.1 mg / kg, preferably at most 0.05 mg / kg, more preferably less than 0.01 mg / kg, furthermore preferably less than 0.005 mg / kg in particular less than 0.001 mg / kg.

The odor-reduced pKM preferably has a proportion of naphthalenes (DIN EN 16181: 2017-1 1 / draft) of less than 5 mg / kg. The sum of the 18 EPA-PAK excluding BG (DIN EN 16181: 2017-11 / draft) is preferably less than 5 mg / kg. No proportion (<0.1 mg / kg) of benzo (a) anthracene, chrysene, benzo (b) fluorathene, benzo (k) fluranthe, benzo (a) pyrene, indenol (1, 2,3-cd) is preferred Pyrene, dibenzene (a, h) anthracene, benzene (ghi) perylene, benzo € pyrene and benzo (j) fluoranthene can be detected (DIN EN 16181: 2017-1 1 / draft).

The odor-reduced pKM differs from materials according to the prior art, for example, in that

that it has a BET of at least 5 m ² / g and

The porosity of a rubber article produced by pressureless vulcanization using 50 phr of the odor-reduced pKM is more comparable to the porosity of a rubber article produced by pressureless vulcanization using 50 phr N550 than with the porosity of a rubber article produced by pressureless vulcanization using 50 phr LignoBoost lignin was produced.

that it has a BET of at least 5 m ² / g,

has a Klason lignin content of at least 90% and

the proportions of substances associated with an unpleasant odor, for example dimethyl disulfide, measured at 160 ° C. in the HS-GC / MS, are reduced to less than 30%, preferably less than 25%.

[0030]

Example 1 :

First process step:

A pKM (material A) was obtained from softwood lignin by stabilization under hydrothermal carbonization conditions. Second process step:

10 kg of material A with a BET of 40 m ² / g (determined according to ASTM D 6556-14) were treated in a drying cabinet over a period of 3 hours at a temperature of 250 ° C. The oxygen content in the drying cabinet was reduced to less than 10% by volume during heating, during the holding time and during cooling by rinsing with knitted fabric. The heating rate was 1 K / min from a temperature of 150 ° C. 9.6 kg of odor-reduced pKM (material B) with a BET of 30 m ² / g were obtained.

Material A and material B were measured in the headspace GC / MS at 160 ° C. The following results were obtained:

The materials A and B do not differ significantly in their elemental sulfur content despite the decrease in sulfur-containing compounds. In the elemental composition, only the carbon content of the material B treated by the method according to the invention is increased. Material B also shows a 9% increase in the proportion of fixed carbon.

[0031]

Example 2:

Material A (pKM) from example 1 with a BET of 40 m ² / g, material B (odor-reduced pKM) from example 1 with a BET of 30 m ² / g and a third pKM (material C) with a BET of 30 m ² / g were mixed into an SBR matrix as filler. After vulcanization, the course of the stress-strain curve was recorded in a tensile test. The tensile strength results are shown in Table y.

Tensile strength Elongation at break s 50% s 100% s 200% s 300% s 500%

[Mpa] [%] [Mpa] [Mpa] [Mpa] [Mpa] [Mpa]

Material A 12.8 307 1.2 2.9 8.1 12.1

Material B 12.9 409 1.2 2.6 6.8 10.1

Material C 10.2 416 1.0 2.1 5.4 8.1

The preparation of the mixture for the elastomer compounds as well as the manufacture of the vulcanizates took place according to the following recipe using the following processes:

Recipe:

All quantitative data relate to 100 parts of rubber (parts per hundred rubber - phr). The mixture was produced using the following procedure:

The mixtures were produced using a Haake Rheomix 3000 measuring kneader (tangential rotor geometry) with a filling level of 70%. The mixing temperature was about the

Speed control kept constant. The mixing time was approx. 20 minutes. The vulcanization took place at 160 ° C according to the optimal t90 time determined in the rheometer plus one minute for each millimeter of panel thickness.

[0032]

Example 3:

Material A (pKM) from example 1 with a BET of 40 m ² / g and material B (odor-reduced pKM) from example 1 with a BET of 30 m ² / g were mixed into an EPDM matrix as filler. After vulcanization, the course of the stress-strain curve was recorded in a tensile test. The results are shown in table x:

Tensile strength Elongation at break s 50% s 100% s 200% s 300% s 500% [Mpa] [%] [Mpa] [Mpa] [Mpa] [Mpa] [Mpa]

Material A 8.1 677 1.2 2.0 3.7 4.6 6.0 Material B 7.3 626 1.4 2.3 4.2 5.1 6.2

Recipe

The mixtures were produced using the following procedure:

The mixtures were mixed using a mixer W & P Type GK1, 5E (interlocking rotor geometry) with a filling level of 70%, with a mixer temperature of 40 ° C. and a speed of 40 rpm. manufactured.

The vulcanization was carried out by baking at 160 ° C. in accordance with the optimal t90 time determined in the rheometer. For the unpressurized vulcanization, 2 test specimens per mixture variant were produced from a 6 mm thick mixed sheet by means of a volume punch and vulcanized for 30 minutes at 160 ° C. in a heating cabinet. After removal, a test specimen was cut open immediately and assessed for odor and porosity and the second was cut open and assessed after cooling to room temperature.

Since with pressureless vulcanization in production the material generally goes through an extrusion process in which it is exposed to a pressure in the nozzle that largely removes the air it contains, it can be assumed that the porosity in real production is even lower than in this laboratory procedure is determined.

The rubber article produced using material A had the following porosity:

The rubber article produced using material B had the following porosity:

[0033]

Example 4:

First process step:

A pKM (material D) was obtained from softwood lignin by stabilizing it under conditions of hydrothermal carbonization.

Second process step:

The material D with a BET of 31.1 m ² / g was subjected to the process according to the invention at different temperatures. Nitrogen was chosen as the process atmosphere. The material D was treated at the treatment temperatures given in the table. The heating took place either without control of the heating rate (spontaneous) or with a heating rate of 10 Kelvin / 10 minutes from a critical temperature of 150 ° C (from 150 10K / 10MIN). The BET of the odor-reduced pKM is also given.

This example shows that a temperature increase without controlling the heating rate up to a treatment temperature of 200 ° C can take place without any significant influence on the BET.

This example also shows that a temperature increase with control of the heating rate from a critical temperature of 150 ° C up to a temperature of 400 ° C can take place without any significant influence on the BET.

Claims

Expectations

1. A method for producing a reduced-odor particulate carbon material characterized in that

a particulate carbon material obtained by precipitation of a starting material completely or partially dissolved in a liquid is provided,

the particulate carbon material is then treated in a second process step by heating in a gas atmosphere, whereby an odor-reduced particulate carbon material is obtained and the process temperature in the second process step is a maximum of 50 ° C below and a maximum of 50 ° C above the further processing temperature and / or the usage temperature and

the process temperature does not exceed a maximum temperature and does not fall below a minimum temperature.

2. The method according to claim 1, characterized in that the

Further processing temperature is at least 150 ° C and maximum 180 ° C.

3. The method according to any one of the preceding claims, characterized in that the further processing temperature and / or the use temperature is below the temperature of the first process step and the process temperature does not exceed the temperature of the first process step.

4. The method according to any one of the preceding claims, characterized in that a lignin-based starting material is stabilized in the first process step under conditions of hydrothermal carbonization and in the second process step the temperature of the stabilization is not exceeded under conditions of hydrothermal carbonization.

5. The method according to any one of the preceding claims, characterized in that the particulate carbon material has a BET of at least 5 m ² / g after the first process step.

6. The method according to any one of the preceding claims, characterized in that the drop in BET during the second process step is less than 30%.

7. The method according to any one of the preceding claims, characterized in that the pKM is heated in the second process step to the process temperature from a critical temperature with a controlled heating rate of less than 30 ° C / minute.

8. The method according to any one of the preceding claims, characterized in that the treatment of the pKM takes place at the process temperature under a process atmosphere.

9. The method according to any one of the preceding claims, wherein the pKM is softwood or hardwood-based.

10. odor-reduced particulate carbon material obtainable by the process according to any one of claims 1 to 6.

11. odor-reduced particulate carbon material according to claim 7, characterized in that it has a BET surface area of at least 5 m ² / g and the porosity of a rubber article obtained by pressureless vulcanization using 50 phr of the odor-reduced pKM is closer to that of the porosity of a Rubber article that was produced by pressureless vulcanization using 50 phr N550 than with the porosity of a rubber article that was produced by pressureless vulcanization using 50 phr LignoBoost Lignin.

12. Odorless particulate carbon material according to claim 7, characterized in that the content of dimethyl sulfide and guaiacol is below 1 mg / kg.

13. Use of the odorless particulate carbon material according to one of claims 7 to 9 or obtained by a process of claims 1 to 6 as an additive in polymer mixtures, in particular elastomer mixtures.