Carbon black compositions and their applications

The present invention relates to carbon black compositions. Furthermore, the invention relates to processes to make such carbon black compositions. A further subject matter of this invention consists in blends of carbon black compositions with various polymers. The invention also relates to the use of the carbon black compositions of this invention in a variety of applications.

Carbon black has been coated with platinum for fuel cell applications. Reference is made to the <patcit id="pcit0001" dnum="US4447506A"><text>US patents 4,447,506</text></patcit>, <patcit id="pcit0002" dnum="US4137373A"><text>4,137,373</text></patcit>, <patcit id="pcit0003" dnum="US5759944A"><text>5,759,944</text></patcit>. In part these references also disclose the simultaneous use of platinum nickel alloys as well as platinum nickel gold alloys in conjunction with carbon black for the fuel cell catalytic application.

The nickel is used to modify the platinum crystal lattice dimensions, see e.g. <patcit id="pcit0004" dnum="US5759944A"><text>US patent 5,759,944</text></patcit> column 4, line 51.

In many applications finely divided metal is used. Carbon black is a known inert material used as pigment, reinforcing material for rubber, filler in polymers. In addition, carbon black is used as a carbon source in processors for producing other carbon materials including nanometer carbon such as carbon nanotubes.

In accordance with this invention, novel carbon black metal compositions or respectively carbon black coated with metal are provided. These novel carbon black compositions have a variety of applications which can be divided into two groups, namely <ol id="ol0001" ol-style=""><li>a. applications in which the metallic properties of the metal coating the carbon black is utilized;</li><li>b. applications in which the coated carbon black serves as a source of the metal in a reaction.</li></ol>

The term coated is not to be understood as limited to a continuous coating, rather, it refers to any connection of the metal component to the carbon black.

The problem solved in accordance with this invention is broadly to provide a carrier for metal to be introduced either into polymer matrices in order to provide modification to the polymer properties or into reaction environments in which the metals function as reaction stimulating nuclei or seeds or catalytic particles.

This problem in its most general form is solved by the claimed carbon black compositions. Preferred further embodiments are contained in the dependent claims as well as in the claims relating to applications and blends of the carbon black compositions. Furthermore, the claimed processes for producing the carbon black composition constitute an embodiment of the invention.

A first embodiment of this invention is a carbon black composition consisting essentially of carbon black and a metal component selected from the group consisting of <ul id="ul0001" list-style="none" compact="compact"><li>Y (Yttrium), Cu (Copper), Ir (Iridium). Optionally these metals may be used in combination with one or more further metals, specifically with one or more of the metals of the group of Ni, Fe, Co (nickel, iron, cobalt), particularly Y and Ni.</li></ul>

The carbon black composition of this invention in accordance with this embodiment can also be characterized as comprising carbon black and the metal component listed.

The preferred carbon black composition contains more than 1 weight percent of the metal component. In particular it is characterized by containing more than 5, most preferably 30 to 85 weight percent of metal component in the composition wherein 100 weight percent is based on the carbon black and the metal component together.

The Yttrium caoted carbon black composition containing yttrium and/or copper and/or iridium is a further alternative embodiment of this invention.

The carbon black and the metal component are bonded, the bonding nature being not yet finally clarified. The bonding is, however, significant enough mechanically to prevent a substantial separation of carbon black and the metal component during the regular applications for instance in a mixer (internal or continuous, as used in the rubber and plastic industry) or a compactor or other mechanical blending devices, or during an ultrasonic dispersion.

A further aspect of this invention relates to a process for producing a carbon black composition of this invention. In accordance with the first embodiment of this process, the process comprises <ol id="ol0002" ol-style=""><li>a. impregnating carbon black with a compound (or compounds) of the metal composition mentioned above, and</li><li>b. drying the carbon black/metal composition and reducing the metal compound(s). The drying and reducing steps are preferably carried out by first drying and thereafter reducing. The reducing step is carried out by contacting the impregnated carbon black with a reducing agent, in particular hydrogen under elevated temperature. Other reducing agents can also be used. Examples for such other reducing agents are hydrazyne or sodium hypophosphite.</li></ol>

The impregnation can be done in accordance with this invention by either contacting the carbon black in an aqueous slurry with a metal compound or metal compounds present in the slurrying liquid. Examples for such metal compounds for the metal nickel are <tables id="tabl0001" num="0001"><table frame="topbot"><tgroup cols="3"><colspec colnum="1" colname="col1" colwidth="35mm" /><colspec colnum="2" colname="col2" colwidth="23mm" colsep="0" /><colspec colnum="3" colname="col3" colwidth="66mm" colsep="0" /><thead><row><entry align="center" valign="top" /><entry align="center" valign="top">Solubility (g/l)</entry><entry align="center" valign="top">Concentration of nickel at the saturation (g/l)</entry></row></thead><tbody><row rowsep="0"><entry align="center">NiCl₂.6H₂O</entry><entry align="center">2540</entry><entry align="center">620</entry></row><row rowsep="0"><entry align="center">NiSO₄.7H₂O</entry><entry align="center">750</entry><entry align="center">150</entry></row><row rowsep="0"><entry align="center">Ni(NO₃)₂.6H₂O</entry><entry align="center">2385</entry><entry align="center">480</entry></row><row><entry align="center">(CH₃COO)₂Ni.4H₂O</entry><entry align="center">not available</entry><entry align="center">100</entry></row></tbody></tgroup></table></tables>

An increased solubility will allow to depose sufficient nickel on the carbon black structure. In that sense, the nickel compounds with high solubility are the preferred ones for the impregnation step of this type. The drying method (spin flash, infrared, solvent displacement), allows the control of the deposit morphology. The nickel compounds must be reducible to the nickel metal under conditions which do not significantly change the carbon black structure.

In accordance with a yet further more specific embodiment of this invention the impregnation is carried out by a precipitation technique. Under this embodiment the carbon black is contacted preferably in a slurry with a nickel compound which does, however, not sufficiently settle on the carbon black but requires a precipitation step. In accordance with this step the slurry is contacted with a compound which causes a conversion of the nickel compound to another nickel compound which is no longer soluble and will as such settle on the slurried carbon black particles.

Examples for this procedure include the following in accordance with the invention: <ul id="ul0002" list-style="none" compact="compact"><li>Nickel compounds which can be used for this process include <ul id="ul0003" list-style="none"><li>nickel chloride</li><li>nickel carbonate</li><li>nickel acetate</li><li>nickel sulfate</li></ul></li><li>Precipitation agents which can be used for this process include <ul id="ul0004" list-style="none"><li>ammonia</li><li>sodium carbonate</li><li>potassium hydroxide</li><li>urea</li><li>sodium hydroxide</li></ul></li></ul>

Other metal compounds which would be useful for forming metal compound crystals on the carbon black surface are:

Cobalt acetate, Ni acetate., yttrium acetate, cobalt nitrate.

The impregnated carbon black particles also have to be dried and in accordance with the preferred embodiment washed such as to remove all detrimental ingredients. As such for instance sodium chloride as well as alkali metal ions or halogen ions can be removed.

The third possibility here seen within the generic term of impregnation consists in a crystallization. Under this method metal compounds such as compounds of nickel are allowed to crystallize from a solution, within which the carbon black particles are suspended, onto those particles. The advantage of this method is that a relatively high metal content is achievable, even with salts having a low solubility.

The crystallization in accordance with a preferred example can be carried out in the case of nickel using a solution of an acetate of nickel tetrahydrate. Crystals of nickel acetate * 4 H₂O are not present after a thermal drying step.

The carbon black particles impregnated with the metal compound(s) in accordance with either the regular impregnation procedure, or the specific precipitation procedure or the specific crystal growth procedure are then subjected to a reduction step. In the preferred embodiment this reduction is carried out by contacting the dried impregnated carbon black particles with hydrogen under elevated temperatures.

In accordance with a yet further embodiment, the invention comprises a process to produce the carbon black compositions of this invention. In this process, the carbon black particles are subjected to one or more electroless plating steps after the carbon black has been treated to render its surface capable for electroless plating. In particular, the carbon black may have been subjected to implanting seeds or catalytic sites on its surface. Typical active sites are obtained by the following chemicals: <ul id="ul0005" list-style="dash"><li>HNO₃ peroxides, O₂, O₃, and other strong oxidants;</li><li>SnCl₂, PtCl₄(6).</li></ul>

Typical electroless plating conditions include as examples contacting solutions with the following ingredients showing the temperatures of use:

<u style="single">Method 1</u>

<tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="14mm" /><colspec colnum="3" colname="col3" colwidth="35mm" /><colspec colnum="4" colname="col4" colwidth="15mm" /><colspec colnum="5" colname="col5" colwidth="10mm" /><tbody><row><entry>NiCl₂</entry><entry>32 g/l</entry><entry>Na Hydrogenocitrate</entry><entry>11.7 g/l</entry><entry>90°</entry></row><row><entry>NiSOy</entry><entry>13 g/l</entry><entry>NaHPO₃</entry><entry>73 g/l</entry><entry>90°</entry></row><row><entry>Pb(NO₃)₂</entry><entry>2.7 g/l</entry><entry>NH₄Cl</entry><entry>100 g/l</entry><entry>90°</entry></row></tbody></tgroup></table></tables>

<u style="single">Method 2</u>

0.6 M N acetate or NiOH + H₂SO_y in ethylene glycol 185 - 194°C

A further embodiment of this invention relates to a blend of polymer and the carbon black compositions in accordance with this invention. Any polymer can be used, for example a rubber or a thermoplastic polymer, in particular an olefin polymer, more specifically an ethylene - or propylene polymer or copolymer. Other thermoplastic polymers include poly carbonates, ABS, polyamides, polyoxy methylene.

A particularly interesting embodiment of these blends in accordance with this invention is one which comprises rubber and the carbon black composition of this invention. In such a blend the carbon black fulfils its reinforcing or cross-linking function on the rubber while at the same time the metal is introduced into the rubber changing the properties of the rubber.

In these blends the carbon black content is preferably 1 to 60 weight percent, based on the polymer and the carbon black (excluding the metal content) as 100 weight percent. The carbon black content depends on the type of the carbon black coated and the overall composition of the composites. Furthermore, the invention resides in the use of the carbon black compositions herein defined and claimed in various applications.

In a first embodiment the applications relate to the use of the carbon black compositions in the hot gas phase of a carbon converting furnace. By injecting these carbon black composition particles into the hot gas phase mentioned it is possible to very finely and in a very controlled manner introduce metal on a totally compatible carrier, namely the carbon black which works also as a further carbon source in such a reactor. In particular, the carbon black compositions are used in a nanometer carbon forming reactor, specifically in one that is used for producing nanotubes. In fact, the carbon black composition in accordance with this invention can be utilized as the sole feedstock for the production of such nanotubes by injecting these carbon black composition particles into the furnace, in particular into the arc itself, wherein a vaporization occurs and due to the presence of the metal, preferably yttrium, is condensed at least in part to form a carbon nanotube shaped material.

For this application it is preferred to employ carbon black compositions which contain 0.5 to 60 weight percent metal component, in particular yttrium.

A yet further use of the carbon black compositions of this invention involves the use of the herein claimed blends of the carbon black composition with polymers.

Further applications of the carbon black coated with metal and preferred uses of this metal doped coated black in accordance with the invention include the following:

An EMI shielding. In particular this EMI shielding can be desirable and uses in accordance with the invention as well as products in accordance with the invention include the following: <ul id="ul0006" list-style="dash"><li>Shielding boxes. These can be made from or contain film or foil of polymer with the carbon black coated with metals in accordance with the invention.</li><li>Packaging materials, in particular for packaging sensible electronic materials. These packaging materials can comprise or consist essentially of film of polymer material with the middle coated carbon black in accordance with the invention.</li><li>Adhesives; these would again contain the metal coated carbon black to provide these adhesives not only with a staining capability but also with specific electrical and/or magnetic properties.</li><li>Fibers containing the metal coated carbon black of this invention, is in particular cloth comprising such fibers.</li><li>Coatings made from a carrier material and the metal coated carbon black of the invention.</li></ul>

Precursors or catalysts for carbon nanostructures, particularly carbon nanotube productions.

Further preferred embodiments and features and details of this invention will become apparent from the allowing description of examples and the drawings in which; <ul id="ul0007" list-style="none"><li>Figure 1 shows a graph of the nickel content as a function of the nickel concentration and the impregnation solution before reduction.</li><li>Figure 2 shows a TEM of a nickel doped carbon black particle.</li><li>Figure 3 shows an x-ray diffraction spectrum of the carbon black after the deposition of nickel acetate as a nickel precursor by crystallization.</li><li>Figure 4 shows an SEM of a carbon black particle with a ferromagnetic nickel coating.</li></ul>

The carbon blacks.

For this invention in principle all types of carbon blacks are useable from regular carbon black, (specifically from the following processes: MMM process, furnace, channel, thermal, lamp, acetylene, gasification, plasma), to nano particle size black. The graphite carbon can be considered as well as any carbon structure. The black chosen as the base material onto which the metal is coated depends on the application of the product. In the case of applications of the coated carbon black in rubber the carbon black used will be one which contributes the desired reinforcement or cross-linking to the rubber. In the case of a shielding the carbon black will be selected under criteria of optimizing the shielding properties as well as the processing.

For the various applications the following ranges of carbon blacks and their properties are presently preferred: <tables id="tabl0003" num="0003"><table frame="all"><tgroup cols="3"><colspec colnum="1" colname="col1" colwidth="70mm" /><colspec colnum="2" colname="col2" colwidth="55mm" /><colspec colnum="3" colname="col3" colwidth="41mm" /><thead><row><entry rowsep="0" valign="top">Application</entry><entry rowsep="0" valign="top">Nitrogen specific surface area (m²/g)</entry><entry rowsep="0" valign="top">DBP absorption (ml/100g)</entry></row><row><entry valign="top" /><entry valign="top">ASTMD4820</entry><entry valign="top">ASTM D2414</entry></row></thead><tbody><row><entry>Rubber reinforcing applications</entry><entry>35-150</entry><entry>60-200</entry></row><row><entry>Shielding applications</entry><entry>35-1600</entry><entry>100-700</entry></row><row><entry>Catalyst carrier for specialty carbon black production, in particular nanotubes</entry><entry>5-150</entry><entry>30-200</entry></row></tbody></tgroup></table></tables>

For the following examples two commercially available carbon blacks, namely ENSACO 250 and ENSACO 350 obtained from Erachem Comilog have been used. These carbon blacks have the following properties: <tables id="tabl0004" num="0004"><table frame="all"><tgroup cols="3"><colspec colnum="1" colname="col1" colwidth="65mm" /><colspec colnum="2" colname="col2" colwidth="25mm" /><colspec colnum="3" colname="col3" colwidth="25mm" colsep="0" /><thead><row><entry align="center" valign="top" /><entry align="center" valign="top">Ensaco 250 gr</entry><entry align="center" valign="top">Ensaco 350 gr</entry></row></thead><tbody><row><entry align="center">Nitrogen specific surface area ASTM D4820</entry><entry align="center">≈65 m²/gr</entry><entry align="center">≈ 800 m²/gr</entry></row><row><entry align="center">Pour density ASTM D1513</entry><entry align="center">≈ 190 kg /dm³</entry><entry align="center">≈ 140 kg /dm³</entry></row><row><entry align="center">pH ASTM D1512</entry><entry align="center">11</entry><entry align="center">11</entry></row></tbody></tgroup></table></tables>

Example 1

(Comparative Example)

Carbon black-nickel by impregnation-reduction.

Both ENSACO 250 and ENSACO 350 were impregnated with nickel. The impregnation was done by stirring 60 g of the carbon black suspended in 600 ml of a nickel solution containing nickel in various concentrations; 10 ml of acetone were added at the beginning of the slurrying in order to speed up the dispersion. The pulping of the carbon black was carried at surrounding temperature when the solubility of the salt used was sufficient. In order to obtain more highly concentrated solutions a working temperature of up to 80°C was used. At the end of the pulping the carbon black and the impregnation solution were separated by filtration using a paper or polypropylene filter. The carbon black was then dried in an oven at 100°C during 15 hours.

The nickel content (before the production step) of the coated carbon black is shown in Figure 1. This Figure also shows the quantity of nickel used in the impregnation solution. In Figure 1 the values represented by a square relate to a nickel acetate-water solution, a diamond relate to a nickel chloride-water solution, a triangle relate to a nickel acetate-ethanol solution, a circle relate to nickel chloride-ethanol solution.

The solid symbols relate to ENSACO 250 as the carbon black, while the empty symbols relate to ENSACO 350.

The impregnated carbon black was dried so that a carbon black-nickel precursor composition was obtained. In addition to drying in a regular oven, flash evaporation can also be considered as one of the means of separating the liquid from the solid material.

In the heating period, the atmosphere is kept inert by N₂ flow

The reductions were carried out at a temperature of 500°C respectively 600°C for durations of between 2.2 and 41 hours. The hydrogen flow was between 20 and 40 ml/min.

The dried material was then subjected to a reduction step. In principle all techniques known in the art to reduce nickel compounds to nickel metal can be employed. Presently preferred is a reduction with hydrogen, preferably at elevated temperatures, also a reduction with hydrazine is possible. The preferred temperature range for the hydrogen reduction is 300 to 610 °C and for the hydrazine reduction is 40 to 80 °C.

Both fluid bed and fixed bed operations for the reduction are possible.

The resulting doped carbon blacks have been investigated. It has been found that the nickel is well crystallized (nearly 100 percent). The various samples had nickel contents of between approximately 9 and approximately 50 weight percent.

The morphology of the nickel coated carbon black is shown exemplarily in Figure 2. One can see that the nickel single crystals are well developed. The crystallite sizes for the nickel doping ranges between approximately 10 nanometers and approximately 10 micrometers. This is also the crystal size range for the other metals in accordance with the preferred embodiment.

Example 2 - (Comparative Example) Nickel coating of carbon black using crystallization and reduction.

In this example the carbon black was suspended in the nickel solution at a temperature of 80°C employing a nickel acetate solution (120 g nickel as acetate salt per liter). For higher doping more of the solution was used. The suspension of carbon black in the nickel solution is then progressively cooled to approximately surrounding temperature conditions and the solvent (water or methanol) is evaporated. Once the agitation of the suspension could no longer be carried out efficiently, the drying was finalized in an oven at 100°C.

From the x-ray spectrum shown in Figure 3 of the obtained product essentially no crystals of nickel acetate tetrahydrate are found.

The reduction of the coated carbon blacks is carried out as described in example 1 at a temperature of 325°C in hydrogen. The SEM pictures of the product after reduction shows the doping of the carbon black with individual nickel crystals sometimes interconnected with each other. These crystals are located on the surface of the carbon black. This technique permits to obtain monocrystalline nickel.

Example 3 - (Comparative Example) Coating carbon black with nickel by precipitation and reduction

In this example the carbon black suspension in a nickel solution was subjected to precipitation by adding various precipitants. The reduction of the nickel hydroxides was thereafter carried out at 600°C in hydrogen with a consumption of 20 ml/min hydrogen employing hydrogen in a quantity of 3 times the stoichiometrically required quantity for total reduction of the nickel compound.

a) Precipitation with sodium hydroxide.

The precipitation of the nickel hydroxide was carried out with various concentrations of sodium hydroxide.

Products were obtained having a nickel content of about 8 weight percent to about 70 weight percent, the weight percent again being based on the total weight of the carbon black and the nickel.

b) Precipitation with ammonia.

The carbon black was suspended in a molar solution of nickel chloride during one hour. The quantity of ammonia used corresponded to about 2.7 times the stoichiometrically required quantity. The ammonia was introduced in the form of a 25 weight percent ammonia solution. The pulp was then brought to the temperature of reaction.

During the reaction water is added such as to compensate for the losses by evaporation and to maintain a constant volume of the solution. The product is washed and filtered. Care was taken to wet the carbon black completely with the solution prior to the precipitation step.

In these runs the nickel compound was precipitated using ammonia. Very fine granules of nickel were obtained after reduction. The ammonia was employed generally in a molar ratio of ammonia to Ni between 1/1 and 6/1.

The resulting product contained a precipitate of approximately 80 percent of the initially present nickel. The average granule size was in the range of 100 nm to 150 nm and the chlorine content less than 1 weight percent. The coated carbon black had a nickel contents which varied from 5.2 to over 85 weight percent.

The results and some of the operating conditions for the precipitation with ammonia are shown in the following Table. <tables id="tabl0005" num="0005"><table frame="all"><tgroup cols="8"><colspec colnum="1" colname="col1" colwidth="16mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><colspec colnum="3" colname="col3" colwidth="21mm" /><colspec colnum="4" colname="col4" colwidth="21mm" /><colspec colnum="5" colname="col5" colwidth="24mm" /><colspec colnum="6" colname="col6" colwidth="23mm" /><colspec colnum="7" colname="col7" colwidth="23mm" /><colspec colnum="8" colname="col8" colwidth="21mm" /><thead><row><entry align="center" valign="top">Run</entry><entry align="center" valign="top">Volume of solution (ml)</entry><entry align="center" valign="top">Dilution pulp (g CB /1)</entry><entry align="center" valign="top">Duration of stripping (h)</entry><entry align="center" valign="top">Temperature °C</entry><entry align="center" valign="top">Comments</entry><entry align="center" valign="top">Yield of precipitation %</entry><entry align="center" valign="top">Nickel content (% weight)</entry></row></thead><tbody><row><entry>ICB48</entry><entry align="center">500</entry><entry align="center">40</entry><entry align="center">3</entry><entry align="center">90</entry><entry align="center">reactor closed and washing</entry><entry align="center">85</entry><entry align="center">30.7</entry></row><row><entry>ICB52</entry><entry align="center">600</entry><entry align="center">60</entry><entry align="center">12</entry><entry align="center">60</entry><entry align="center">washing</entry><entry align="center">65</entry><entry align="center">23.5</entry></row><row><entry>ICB55</entry><entry align="center">600</entry><entry align="center">60</entry><entry align="center">12</entry><entry align="center">75</entry><entry align="center">washing</entry><entry align="center">76</entry><entry align="center">5.2</entry></row><row><entry>ICB69</entry><entry align="center">3850</entry><entry align="center">16</entry><entry align="center">12</entry><entry align="center">61</entry><entry align="center">no additives</entry><entry align="center">59</entry><entry align="center">71</entry></row><row><entry>ICB74</entry><entry align="center">3850</entry><entry align="center">16</entry><entry align="center">12</entry><entry align="center">60</entry><entry align="center">no additives</entry><entry align="center">64</entry><entry align="center">72.7</entry></row><row><entry>ICB75a</entry><entry align="center">3850</entry><entry align="center">16</entry><entry align="center">2 * 5</entry><entry align="center">60-75</entry><entry align="center">stepped-up temperature T°</entry><entry align="center">74</entry><entry align="center">71.25</entry></row><row><entry>ICB75b</entry><entry align="center">3850</entry><entry align="center">16</entry><entry align="center">2 * 5</entry><entry align="center">60-85</entry><entry align="center">stepped-up temperature T°</entry><entry align="center">87</entry><entry align="center">74.33</entry></row><row><entry>ICB75c</entry><entry align="center">3850</entry><entry align="center">16</entry><entry align="center">3 * 4</entry><entry align="center">60-75-85</entry><entry align="center">stepped-up temperature T°</entry><entry align="center">83</entry><entry align="center">75.83</entry></row><row><entry>ICB78</entry><entry align="center">3850</entry><entry align="center">8</entry><entry align="center">12</entry><entry align="center">60</entry><entry align="center">pre-doped carbon black</entry><entry align="center">59</entry><entry align="center">85.33</entry></row><row><entry>ICB79</entry><entry align="center">3850</entry><entry align="center">16</entry><entry align="center">24</entry><entry align="center">60</entry><entry align="center">Tween80¹</entry><entry align="center">65</entry><entry align="center">63.7</entry></row><row><entry>ICB81</entry><entry align="center">3850</entry><entry align="center">16</entry><entry align="center">12</entry><entry align="center">60</entry><entry align="center">CBO²</entry><entry align="center">57</entry><entry align="center">71.1</entry></row><row><entry>ICB83</entry><entry align="center">3850</entry><entry align="center">16</entry><entry align="center">24</entry><entry align="center">60</entry><entry align="center">CPC³</entry><entry align="center">65</entry><entry align="center">69.4</entry></row><row><entry>ICB86</entry><entry align="center">3850</entry><entry align="center">16</entry><entry align="center">12</entry><entry align="center">60</entry><entry align="center">E350gr⁴</entry><entry align="center">64</entry><entry align="center">47</entry></row></tbody></tgroup><tgroup cols="8" rowsep="0"><colspec colnum="1" colname="col1" colwidth="16mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><colspec colnum="3" colname="col3" colwidth="21mm" /><colspec colnum="4" colname="col4" colwidth="21mm" /><colspec colnum="5" colname="col5" colwidth="24mm" /><colspec colnum="6" colname="col6" colwidth="23mm" /><colspec colnum="7" colname="col7" colwidth="23mm" /><colspec colnum="8" colname="col8" colwidth="21mm" /><tbody><row><entry namest="col1" nameend="col8" align="justify">¹ Tween 80 N-cetylpyridine (chloride) is commercially obtained from Sigma Aldrich ² CBO oxidised carbon black ENSACO 250 (Erachem) 5h/90°C in HNO₃³ CPC is N-cetylpyridine (chloride) from Sigma Aldrich ⁴ E350gr ENSACO 350 carbon black from Erachem</entry></row></tbody></tgroup></table></tables>

c) Precipitation with urea

In the next runs urea was employed to precipitate the nickel compound on the carbon black the carbon black is suspended in a solution of nickel salt as before.

The urea was introduced into the suspension of carbon black in the nickel solution by employing an aqueous solution of urea having a urea concentration of 1 to 3 M. The operating conditions for these runs using urea as the precipitant are shown in the following table. <tables id="tabl0006" num="0006"><table frame="topbot"><tgroup cols="12"><colspec colnum="1" colname="col1" colwidth="14mm" /><colspec colnum="2" colname="col2" colwidth="15mm" /><colspec colnum="3" colname="col3" colwidth="22mm" /><colspec colnum="4" colname="col4" colwidth="19mm" /><colspec colnum="5" colname="col5" colwidth="19mm" /><colspec colnum="6" colname="col6" colwidth="21mm" /><colspec colnum="7" colname="col7" colwidth="22mm" /><colspec colnum="8" colname="col8" colwidth="21mm" /><colspec colnum="9" colname="col9" colwidth="23mm" /><colspec colnum="10" colname="col10" colwidth="23mm" /><colspec colnum="11" colname="col11" colwidth="23mm" /><colspec colnum="12" colname="col12" colwidth="24mm" colsep="0" /><thead><row><entry morerows="1" align="center" valign="middle">Run</entry><entry morerows="1" align="center" valign="middle">Ni salt</entry><entry morerows="1" align="center" valign="middle">V_sol Solution volume (ml)</entry><entry namest="col4" nameend="col5" align="center" valign="middle">Nickel Concentration</entry><entry morerows="1" align="center" valign="middle">Carbon black content (gCB/l)</entry><entry morerows="1" align="center" valign="middle">MOlar ratio urea/ni ckel</entry><entry morerows="1" align="center" valign="middle">Stripping duration (h)</entry><entry morerows="1" align="center" valign="middle">temperature (°C)</entry><entry morerows="1" align="center" valign="middle">η Precipitation (%)</entry><entry namest="col11" nameend="col12" align="center" valign="middle">Carbon black after washing</entry></row><row><entry align="center" valign="top">Initial (g/l)</entry><entry align="center" valign="top">Final (g/l)</entry><entry align="center" valign="top">Nickel content (%W)</entry><entry align="center" valign="top">Anion content (%W)</entry></row></thead><tbody><row><entry align="center">ICB5 4</entry><entry align="center">NiSO ₄</entry><entry align="center">600</entry><entry align="center">58</entry><entry align="center">14.5</entry><entry align="center">66</entry><entry align="char" char="." charoff="39">1.7</entry><entry align="center">48</entry><entry align="center">85</entry><entry align="center">75</entry><entry align="center">25.34</entry><entry align="center">11.15</entry></row><row><entry align="center">ICB5 7</entry><entry align="center">NiCl₂</entry><entry align="center">600</entry><entry align="center">57.5</entry><entry align="center">22.5</entry><entry align="center">66</entry><entry align="char" char="." charoff="39">1.7</entry><entry align="center">48</entry><entry align="center">85</entry><entry align="center">61</entry><entry align="center">22.67</entry><entry align="center">3.95</entry></row><row><entry align="center">ICB7 7</entry><entry align="center">NiSO ₄</entry><entry align="center">400 0</entry><entry align="center">60.9</entry><entry align="center">21.8</entry><entry align="center">15</entry><entry align="char" char="." charoff="39">1.7</entry><entry align="center">70</entry><entry align="center">80</entry><entry align="center">65</entry><entry align="center">38.8</entry><entry align="center">18.4</entry></row></tbody></tgroup></table></tables>

The structure of the nickel coated carbon black was comparable in these runs to the one obtained in earlier runs. Small monocrystalline nickel crystals were attached to the carbon black base. The size of the crystals appeared somewhat more uniform and in the range of 10 to 500 nanometers.

Example 4 - (Comparative Example) Nickel doping by an electroless plating methods

a.) In this example the carbon black (Ensaco 250G) was subjected to a treatment in a nickel solution under conditions similar to classic electroless plating. The composition of the solution used for this purpose shown in the following table <tables id="tabl0007" num="0007"><table frame="all"><tgroup cols="2"><colspec colnum="1" colname="col1" colwidth="38mm" /><colspec colnum="2" colname="col2" colwidth="15mm" /><tbody><row><entry align="center">Nickel chloride</entry><entry align="center">32 g/l</entry></row><row><entry align="center">Nickel sulfate</entry><entry align="center">13 g/l</entry></row><row><entry align="center">Nickel hydrogen citrate</entry><entry align="center">11,4 g/l</entry></row><row><entry align="center">Sodium hydrophosphite</entry><entry align="center">73 g/l</entry></row><row><entry align="center">Ammonium chloride</entry><entry align="center">100 g/l</entry></row><row><entry align="center">Led nitrate</entry><entry align="center">2,4 g/l</entry></row></tbody></tgroup></table></tables> The carbon black was suspended in this electroless plating bath at room temperature. The thus obtained suspension is thereafter heated to 80°C. The conditions were chosen to provide 10 g or carbon black per liter of plating solution.

At the end of the reaction the suspension is filtered and the filter cake is washed. The specific conditions as well as compositions are shown in the following table together with the results. <tables id="tabl0008" num="0008"><table frame="all"><tgroup cols="7"><colspec colnum="1" colname="col1" colwidth="12mm" /><colspec colnum="2" colname="col2" colwidth="19mm" /><colspec colnum="3" colname="col3" colwidth="19mm" /><colspec colnum="4" colname="col4" colwidth="21mm" /><colspec colnum="5" colname="col5" colwidth="24mm" /><colspec colnum="6" colname="col6" colwidth="36mm" /><colspec colnum="7" colname="col7" colwidth="39mm" /><thead><row><entry align="center" valign="top">Run</entry><entry namest="col2" nameend="col3" align="center" valign="top">Doping</entry><entry namest="col4" nameend="col5" align="center" valign="top">Operating conditions</entry><entry align="center" valign="top">Temperature °C</entry><entry align="center" valign="top" /></row><row><entry valign="top" /><entry align="center" valign="top">Sn (wt/%)</entry><entry align="center" valign="top">Pd (wt/%)</entry><entry align="center" valign="top">Temp (°C)</entry><entry align="center" valign="top">Duration (min)</entry><entry align="center" valign="top">Nickel content on carbon black (wt/%)</entry><entry align="center" valign="top" /></row></thead><tbody><row><entry align="center">42</entry><entry align="center">2,1</entry><entry align="char" char="." charoff="56">0,52</entry><entry align="center">20-80</entry><entry align="center">45</entry><entry align="center">38,58</entry><entry align="center">Decomposition of the bath</entry></row><row><entry align="center">45</entry><entry align="center">2,1</entry><entry align="char" char="." charoff="56">0,52</entry><entry align="center">20-80</entry><entry align="center">60</entry><entry align="center">1,7</entry><entry align="center" /></row><row><entry align="center">46.1</entry><entry align="center">4,89</entry><entry align="char" char="." charoff="56">1,18</entry><entry align="center">35-85</entry><entry align="center">60</entry><entry align="center">1,38</entry><entry align="center" /></row><row><entry align="center">46.2</entry><entry align="center">4,89</entry><entry align="char" char="." charoff="56">1,18</entry><entry align="center">30-67</entry><entry align="center">60</entry><entry align="center">44,95</entry><entry align="center">Decomposition of the bath</entry></row><row><entry align="center">48.1</entry><entry align="center">4,89</entry><entry align="char" char="." charoff="56">1,18</entry><entry align="center">50</entry><entry align="center">100</entry><entry align="center">48,95</entry><entry align="center">Decomposition of the bath</entry></row><row><entry align="center">48.2</entry><entry align="center">4,89</entry><entry align="char" char="." charoff="56">1,18</entry><entry align="center">40</entry><entry align="center">90</entry><entry align="center">4 à 33</entry><entry align="center">Decomposition of the bath</entry></row><row><entry align="center">48.3</entry><entry align="center">4,96</entry><entry align="char" char="." charoff="56">1,18</entry><entry align="center">40</entry><entry align="center">150</entry><entry align="center">2,22</entry><entry align="center" /></row><row><entry align="center">48.4</entry><entry align="center">4,96</entry><entry align="char" char="." charoff="56">1,18</entry><entry align="center">45</entry><entry align="center">380</entry><entry align="center">2</entry><entry align="center" /></row><row><entry align="center">50</entry><entry align="center">4,96</entry><entry align="char" char="." charoff="56">1,18</entry><entry align="center">40</entry><entry align="center">2880</entry><entry align="center">22,75</entry><entry align="center">Decomposition of the bath</entry></row><row><entry align="center">54</entry><entry align="center">4,96</entry><entry align="char" char="." charoff="56">1,18</entry><entry align="center">40</entry><entry align="center">155</entry><entry align="center">44,06</entry><entry align="center">Decomposition of the bath</entry></row><row><entry align="center">57⁵</entry><entry align="center">2,07</entry><entry align="char" char="." charoff="56">0,67</entry><entry align="center">40</entry><entry align="center">80</entry><entry align="center">44,2</entry><entry align="center">Decomposition of the bath</entry></row><row><entry align="center">59⁶</entry><entry align="center">2,07</entry><entry align="char" char="." charoff="56">0,67</entry><entry align="center">40</entry><entry align="center">300</entry><entry align="center">21,6</entry><entry align="center">Decomposition of the bath</entry></row></tbody></tgroup><tgroup cols="7" rowsep="0"><colspec colnum="1" colname="col1" colwidth="12mm" /><colspec colnum="2" colname="col2" colwidth="19mm" /><colspec colnum="3" colname="col3" colwidth="19mm" /><colspec colnum="4" colname="col4" colwidth="21mm" /><colspec colnum="5" colname="col5" colwidth="24mm" /><colspec colnum="6" colname="col6" colwidth="36mm" /><colspec colnum="7" colname="col7" colwidth="39mm" /><tbody><row><entry namest="col1" nameend="col7" align="justify">⁵ Suppression of led nitrate (inhibitor of the reaction) ⁶ The electroless solution has been diluted 3-fold</entry></row></tbody></tgroup></table></tables>

The results show that the high nickel doping is achieved whenever one had a decomposition of the electroless bath. This is therefore one method of producing nickel doped carbon black employing electroless plating bath suspending carbon black therein and bringing this bath thereafter to decomposition conditions. Thereby high nickel contents are achievable.

The nickel coated carbon blacks with these electroless plating solutions do contain some lead, particularly up to a few, preferably less than 1 weight percent. <ul id="ul0008" list-style="none" compact="compact"><li>b.) Further runs of electroless plating have been carried out using a polyol bath. In an oil submersed receptacle 400 ml of ethylene glycol are heated to 100°C. 66 g of nickel acetate, 6 g of carbon black (ENSACO 250G) have been added. The mixture is stirred and heated to a temperature of 190°C. The reactor receptacle was provided with a reflux to reduce losses of the solvent. The reaction was stopped after the solution changed from a green to a maroon colour approximately after 4 hours. At the end of the reaction the suspension is filtered and the filter cake is washed. The nickel doped carbon black was recovered. An SEM of a carbon black particle containing a fairly large magnetic nickel particle is shown in Figure 4. The nickel particle has been labeled "B". </li></ul>

As a nickel source nickel acetate and nickel hydroxide are preferably used. A certain quantity of sulfuric acid can be used to increase the solubility of the nickel hydroxide.

Example 5

<u style="single">Runs for making metal coated carbon black for catalyst applications, for use in carbon nano particles production reactors, in particular plasma reactors</u>

Carbon black 94%, Yttrium 1

%,

Nickel 5%

Impregnation Yttrium acetate + Nickel acetate on carbon black Ensaco 250 <ul id="ul0009" list-style="dash"><li>Solution Yttrium acetate + Nickel acetate + Ensaco 250 mixing at room temperature</li><li>Filtration</li><li>Drying at 100°C</li><li>Reduction under H₂ at 600°C</li></ul>