DE2809027A1 - PROCESS FOR MANUFACTURING ACTIVATED GRAPHITE AND CATALYSTS CONTAINING IT - Google Patents

Description

PAT £ -NTANWÄLT

A. GRÜNECKER

DR. -IMG

W. STOCKMAIR

OFl ING - Ae6; CALrEO-fl

K. SCHUMANN

DR PER [MAT - CiPL-PWYS.

P. H. JAKOB

PiPt -.- ING

G. BEZOLD

DR HER NAT. - DtPL CHEM

MUNICH

MUNICH 22

MAXIMILIANSTRASSE 43

March 2, 1978 P 12 467

ENGELRARD MINERALS &. CHEMICALS CORPORATION
Wood Avenue South, Metro Park Plaza
Iselin, New Jersey, ITSA

Process for the production of activated graphite and catalysts containing it

809836/0809

TELEPHONE (089) 222862

TELEX O5 - 23 3BO

TELEARAM MONAPAT

HO

The invention relates to graphite materials with particular use as catalyst supports, which are produced by coating low-ash graphite with a platinum compound in solution in an organic solvent medium including a non-volatile organic solvent with the deposition of a small amount of platinum compound on the graphite surfaces. The coated graphite is heated at elevated temperatures in the presence of air or oxygen to remove the solvent and to decompose the platinum compound, with elemental platinum widely remaining on the treated graphite surfaces. Using graphite in the form of small particles or coarse powder of inactive material with a surface area below about 1 m / g, the heating is carried out for a time sufficient to result in a weight loss of graphite particles of as little as 3% , while-

^ * ρ

rend a surface area of at least about 3 m / g is obtained. Coherent or shaped bodies of similarly inactive, low ash graphite are similarly treated to activate their surfaces by depositing small amounts of a platinum compound on these surfaces and then heating with access of oxygen and some weight loss. The activated graphite thus obtained can be impregnated with a catalytically effective amount of a metal of the platinum group or with another catalytically active metal or a compound.

It has been found that the partial oxidation of high purity graphitized carbon can provide a useful substrate for the dispersion of materials such as platinum which gives good catalytic activity. In comments by M. Boudart and CH Bartholomew in Journal of Catalysis, Volume 25, pages 173-176 (1972), a very expensive graphite channel black with a very high BET surface area of 87 m ² / g becomes a 0.297 mm (48 mesh) powder ground and

-809836/0809

about 12 hours in air in a muffle furnace at 600 ° C burned a weight loss of about 50%. The emerging Particles become hydrophilic and provide a carrier that can adsorb inorganic salts. For example, was Chloroplatinic acid with or without other inorganic compounds in a benzene-ethanol medium to produce a well dispersed platinum catalyst used. However, the large loss of material during firing causes such a catalyst inevitably becomes very expensive for most applications, and it can still cause the material becomes undesirably fragile.

It is also known the surface of particulate! To increase the graphite material by heating the graphite in an atmosphere of carbon dioxide at a temperature of about 1000-1100 ⁰ C. Such treatment of graphite materials with particle sizes in the range roughly 1 to 6 mm and an initial surface area is determined

according to the BET gas adsorption method, of about 1 m / g was investigated. Heating at 1000 ^° C. for 1 hour results in a weight loss of about 20% and a surface increase of only about 1.5 m / g, while heating during

several hours the surface increases to about 3 m / g with weight losses of more than 50%, although an experiment has been reported at which about 4.5 m / g was obtained with a weight loss of about 30% (cf. e.g. C.N.Spalaris, J.Phys. Chem., Vol. 60, pp. 1480-1483, 1956); In any case, are severe weight loss as well as very harsh temperature conditions and a special environment are required for a surface of about 3 m / g or more.

It has thus been found that only very expensive treatments require heating in the absence of free oxygen and with great loss of graphite during heating, have been effective for one in the past material increase in the surface of the relatively inactive

809836/0809

Graphite. Graphite powders activated by expensive known methods are useful as supports for catalytically active materials. A particularly well activated graphite exhibits a large surface area and a relatively high threshold oxidation or ignition temperature, and there is a great need for catalysts based on them that can be economically manufactured. For such purposes, the graphite starting material can that activates who is the, be considered inactive if it is in particulate form, or has been reduced in size by crushing and sieving to particles which are suitable for surface measurement, when its surface by about 1 m / g lies. Such surfaces, to which reference is made in the following and in the appended claims, are measured by the known BET (Brunauer-Emmett-Teller) method or by an equivalent method.

In the present application, the term “surface” is also intended to include the term “surface area ¹¹ ”.

The invention relates to a new and improved method for activating inactive graphite, which is characterized in that a graphite mass with an ash content of less than about 2% by weight with a soluble platinum compound in solution in an organic solvent medium which is a non-volatile organic solvent comprises, for deposition on the surfaces of the graphite mass exposed to the solution, an amount of the solution containing at least about 0.004 mg elemental platinum / cm 2 of such surfaces. The graphite mass carrying the platinum compound is then heated at elevated temperature with the admission of oxygen to the exposed surfaces to remove the organic solvent medium and to decompose the platinum compound, with elemental platinum remaining distributed on the surface. The heating

809836/08 0 9

is continued for a time sufficient to result in a weight loss of at least about 5% based on the weight of the portions of the graphite mass extending 1 mm below the exposed surfaces so treated and activated.

According to a feature according to the invention in treating a hasse made of low ash graphite in the form of a coherent or shaped body of graphite to activate the exposed surface of the body the platinum compound in solution on the surface of the The body is deposited, and the heating takes place under oxygen access to the exposed surface, which is then connected to the catalytically active material is provided and is used in carrying out the catalytic reactions by one gaseous reactants in contact with the treated, exposed surface of the body.

According to a preferred embodiment of the invention, a particulate mass made of graphite is included low ash content treated with the platinum solution to put a lot of graphite mass on the surfaces of the particles to deposit a solution that contains at least about 75 ppm elemental platinum, based on the total weight of the particles, this minimum amount of platinum is generally equivalent to the aforementioned amount of 0.004 mg / cm, based on the gross geometric or superficial or apparent area of the exposed surface or surfaces both a mass of graphite particles and a coherent body of graphite «The heating takes place similar, so that a loss of at least about 3 wt.? 6 the weight of the particles. The resulting activated graphite particles can act with a catalytically active Amount of active catalyst material to be coated. Catalytic reactions can be carried out by

809836/0809

gaseous reactants through a stationary bed or a fixed bed of the treated and coated particles conducts.

Corresponding to a further feature of the invention becomes a produced object in the form of a graphite mass created with surfaces that are activated by heating in the presence of elemental platinum that is on them Surfaces is distributed, with a substantial burning off of the graphite takes place therefrom and the platinum distributed on it remains. This graphite mass can be in the form of a coherent graphite body, of which at least one side has such activated surfaces. In another embodiment, the graphite is in the form of a particulate Composition whose particles have activated surfaces, preferably with a surface area of at least about 3 m / g. Such particulate material contains about 75 to 2000 ppm of elemental platinum based on that distributed thereon Weight of the particles.

According to a further embodiment of the invention In the process, a carbonaceous material is oxidized by treating the material in gaseous form under oxidizing conditions Conditions with a catalyst in the form of a graphite mass which can be a coherent graphite body with an activated one Surface or the a mass of particulate! Graphite material can be the particles of which have activated surfaces own -, the surfaces by heating in the presence of elemental platinum, which is on these surfaces is distributed, have been activated with essentially burning off of graphite from these surfaces and wherein the graphite mass also incorporated a catalytically effective amount of a catalyst material on their activated surfaces or incorporated. Gaseous fuel-air mixtures, especially when using low, carbon-

809836/0809

-JtS-

containing alkane fuels are advantageously treated with such activated graphite surfaces “ which contain a catalytically effective amount of at least one metal. Containing platinum group, oxidized or burned *

Fig. 1 shows a schematic view in vertical Cross-section of a catalytic burner in which particulate graphite catalyst materials made in accordance with the invention be used.

Fig. 2 shows a schematic view in vertical cross section of a catalytic burner in which a shaped, coherent graphite catalyst body, which after the Method according to the invention was produced is used.

Graphite is a crystalline form of carbon that not only occurs naturally, but which is also produced synthetically in large quantities. Synthetic graphite is made by heating carbonaceous materials, such as petroleum coke, in the range from about 900 to 1800 ⁰ C with the formation of amorphous carbon, followed by further heating at temperatures between about 2200 and 3000 ⁰ C to convert the amorphous carbon into the crystalline form manufactured. Although it is possible to use certain forms of natural graphite depending on the crystalline structure and purity, artificial or synthetic graphite is mainly used in the present invention.

Synthetic graphite is commercially available in a wide variety of purities, which can be expressed in terms of ash content. The ash content of graphite is the percentage residue that is obtained when a sample is ^{ignited under sufficient air at about 900 °} C. or higher to constant weight, normally for 1 hour or longer. In general, the ash content of the varies

809836/08 0 9

most synthetic graphites essentially from 0 to 5 weight percent. The ash portion generally contains one or more of the elements silicon, calcium, iron, aluminum, titanium, vanadium, sodium, boron and sulfur. In addition, the ash can contain small or trace amounts of barium, beryllium, bismuth, chromium, cobalt, zircon, lead, manganese, molybdenum, nickel, strontium, tin, tungsten, zinc, mob, tantalum and uranium. Ks is particularly remarkable that _r technical Graphite or are freely commercially available graphite of even trace amounts of platinum.

Graphite is a commercially available material which is available in many varieties and which is produced in physical forms, such as powder, granules, extruded and molded bodies or shapes, available and in a wide variety of structures are available, all of which have extensive applications in metallurgical, chemical, Find the nuclear and aircraft industries.

The application of graphites and graphite structures and shapes in the field of catalysis is limited and poorly developed compared to the use of amorphous carbon. This limited use of graphite may be attributable to the presence of the aforementioned impurities, many of which exhibit a catalytic effect in either a positive or negative sense and some of which interfere with the catalytic effect of a desired metal deposited on the graphite as a catalytic agent. If graphites with a low ash content are sold commercially, one would expect them to be more suitable as catalyst supports than the high grades. Ash content. The graphites with a low ash content and relative purity, ie graphites with an ash content of a maximum of about 2%, are in general in accordance with known processes by graphitizing at extremely high temperatures

809836/0809

- - sr -

Range of about 300O ⁰ C, formed, whereby most of the impurities contained in the carbon are decomposed and volatilized. As a result of this high temperature treatment, most of the commercially available, particulate, synthetic, low ash graphites currently available, such as flakes, granules, pellets, etc., have a surface area of less than 1 m / g. To produce a material that is suitable for many uses in catalytic reactions, this surface area is too low to allow impregnation of the platelet surface or particles with appropriate amounts of catalytically active metals in available form. These graphites can therefore be described as inactive.

The catalyzed and non-catalyzed oxidation and gasification of graphite by molecular or atomic oxygen, dry and humid air, ozone, and carbon dioxide have been studied extensively by P. L. Walker and co-workers. These Authors report extensively on their work in "Chemistry and Physics of Carbon", Walker & Thrower, editors, volumes I-XI, Marcel Dekker, Inc., New York, 1966-1973. The work von Walker should study the mechanism of the oxidation and gasification reactions clarify the oxidation reaction of graphite by microscopic and cinematographic investigations. Of the Influence of catalysts, such as silver, gold, barium, boron, beryllium, calcium, chromium, cadmium, cobalt, copper, iron, Potassium, molybdenum, manganese, sodium, nickel, lead, scandium, strontium, tantalum, tellurium, titanium, vanadium and zinc were used examined and the differences in the oxidative attack in certain, crystallographic directions of the graphite were set out. The surface topography and its change during oxidation and gasification were the main aim of the study. As far as could be assured, there is no practical procedure for cataloging in Walker's work.

809836/0809

lytic production still describe Walker et al graphite materials, which are suitable for most uses as catalytic materials and those of the current one Technology required. It is noteworthy that in these extensive and authoritative studies the Effect of the platinum has not been tested.

In many respects graphite can be viewed as a very desirable catalyst support. He owns one excellent corrosion resistance to acids, alkalis and organic and inorganic compounds. Additionally Graphites with a low ash content are more resistant to oxidation by air or oxygen than amorphous ones Carbon, suggesting such materials as catalyst supports for combustion and oxidation reactions to use. Furthermore, graphite has excellent mechanical strength and is a good conductor of heat, whereby He for applications in chemical reactors with stationary bed or fixed bed, where a good distribution of the heat of reaction a requirement is useful.

The deposition of metals or compounds on graphite is well known. However, such procedures are often troublesome or often do not result in a uniform dispersion of the metals. Such known methods are: Evaporation of metals on graphite using high vacuum sputtering techniques; Impregnating graphite with molten metals such as silver; Production of colloidal metal suspensions by electro-mechanical processes and deposition of the metal colloids on the graphite; Decomposition of Me-. tallcarbonylen into fine metal powder and applying or mixing the metal powder with graphite; Impregnation of Graphite with aqueous solutions of inorganic salts, as described in US Pat. No. 3,759,842; Impregnate of uncatalyzed, pre-burned graphite with a solution from hexachloroplatinic acid and iron (IIl) nitrate in one

809836/0809

Mixture of methanol and benzene, as described by Boudart et al in J. of Catalysis, as previously mentioned, is described; and Impregnation of carbon and graphite with ruthenium acetylacetonate solutions, as described in U.S. Patent 3,850,668.

It is recognized :! that organic solvents die Wet the hydrophobic surface of graphite. To the generation a coating of a metal-containing compound on graphite, it is therefore desirable to coat the graphite with a To treat solution of the metal-containing compound in an organic solvent preparation, so that an adhesive Film from the coating solution containing the metal, is produced. It is useful to explain different types of platinum compounds that are used to perform of the method according to the invention are useful and available and are soluble in organic solvents. Some of the materials mentioned or described above are available for application to surfaces for creating decorative coatings or for such applications as in the formation of reflective, conductive, or other films for electronic or instrument use or similar uses.

The so-called platinum resinates can be used with advantage in the Implementation of the present invention can be used, and they are explained first. Turpentine is typically a mixture of bicyclic terpenes, like pinene, monocyclic Terpenes, such as terpinene, abietic acid (cyclic diterpene resin acid) and abietic anhydride. Balm is typically a slightly less volatile mixture, rich in terpenes and various diterpeii resin acids, containing sesquiterpenes, such as caryophyllenj cinnamic acids and benzoic acids or their non-resinous esters must be used for the described use not be present. Process for the sulfurization of such

809836/0809

Mixtures have been known for a long time. So "describes P. Boudnikoff (Compt. Rend. 196, pages 1898-9, 1933) the preparation of a sulphurized product called terpene sulphide by boiling a mixture of larch turpentine with sulfur flowers or nitrogen sulphide, N ^ S ,, during 11 / 2 hours at 160 to 170 ⁰ C. the terpene product can sulfide with goID (III) chloride or potassium tetrachloroaurate with the formation of gold resinate implemented. F. Chemnitius describes (Sprechsaal 60, p.226, 1927) resin, the preparation containing a platinum , which is soluble in essential oils or other carriers, by reacting sulphurized balsam in alcoholic solution with a platinum salt (especially hexachloroplatinic acid), distilling off the alcohol and purifying to produce a solid product. Related resin, rosin acid and terpene materials and mixtures can be prepared in a similar manner The resulting sulfurized terpene or sulfurized resin can similarly be treated with a platinum salt r to produce a soluble platinum-containing material known as platinum sulfate or simply platinum resinate, as described in US Pat. No. 3,022,177 and similarly in US Pat. No. 3,092,504 (e.g., Example XII). On this literature. expressis verbis reference is made. Similar processes are described in U.S. Patents 2,402,698 and 2,407,265, in which the formation of sulfurized terpene compounds or terpene-sulfur complexes from 2-pinene (cc-pinene) _f 2 (10) -pinene (β- Pinene), p-mentha-1,8-diene (dipentene), p-mentha-1,4 (8) -diene (terpinolene), p-menth-3-ene (menthen), p-menth-1- en-8-ol (a-terpineol), camphene (3,3-dimethyl-2-methylennorbornane) and mixtures of terpenes found in turpentine is described. These sulphurized terpenes are obtained by reacting the terpenes with equimolar or higher proportions of sulfur for 8 hours or more at about 150 ^° C. under autogenous pressure and explain the large number of terpenes and related materials that can be used separately or in a mixture of the types, as in turpentine and balm to be found

809836/0809

which can be sulfurized. The above mentioned patents explain the formation of sulforesinates, and with them the sulforesinates are used in the manufacture of resin ^ th of various metals used in decorative compositions or as intermediates in manufacture of thiols (mercaptans) and their other derivatives, which may contain noble metals, can be used.

As mentioned above, platinum resinate can be found in essential oils or other non-volatile, organic carriers such as Oils of lavender, rosemary, aniseed, sassafras tree or laurel, wintergreen and fennel, etc., are dissolved, which may also contain more volatile solvents or diluents such as turpentine and nitrobenzene. The one prepared in this way Solution with or without other film-forming ingredients can be applied to various substrates with production a coating containing the platinum resinate can be applied. For example, after application in a thermoplastic Medium on refractory substrates such as glass, ceramic and stainless steel, the platinum resinate or mixtures Various coatings containing metal resinates are fired, with very decorative precious metal finishes or end coatings (U.S. Patent 3,092,504). Contains a typical platinum resinate solution in an essential oil carrier 12% by weight metallic platinum. Solutions in such mainly non-volatile organic carriers made from resinates other precious metals and base metals are similarly available.

Another class of platinum-containing compounds that are produced in organic solvents from coating compositions with high or higher platinum content are disclosed in the aforementioned U.S. Patent 3,022,177. These compounds are soluble, halogen-platinum-containing mercaptide sulfide compounds. Such compounds can also be used as soluble halogeno-

809836/0809

(alkylthio) platinum (II) complexes with alkyl sulfides in which the alkyl groups can be modified, as indicated by the formula RS-Pt-XY, where R is selected from the group containing: alkyl, substituted Alkyl, aralkyl and terpenyl; X is halogen; and Y is selected from the group consisting of: alkyl sulfides, substituted alkyl sulfides and heterocyclic sulfides with a -CH ₂ SCH ₂ bond in the ring, the two alkyl or modified alkyl groups together containing at least 7 carbon atoms.

Examples of such soluble, halogenoplatinum-containing mercaptide sulfide complexes are the following, vrorin die Alkyl groups in both the mercaptide and sulfide moieties not substituted or otherwise modified are:

Chlorine (tert-heptylthio) platinum (II) butyl sulfide Chloro (octylthio) platinum (II) ethyl sulfide.

In the following complex, the mercaptide moiety has a cyclic terpenyl group; an example of such Groups involved in the manufacture of turpentine thiols by sulfurization of terpenes (such as those in turpentine and balsam are present), followed by hydrogenation:

Chlorine (pinenthio) platinum (II) methyl sulfide or Chloro (pinanylthio) platinum (II) methyl sulfide.

The latter designation indicates that all or part of the terpene moiety is during the formation of terpenyl marcaptan (Pinene mercaptan) which is then saturated with potassium tetrachloroplatinate (II) and methyl sulfide is reacted to form the complex.

A complex with good solubility containing a substituted alkylthio group is the compound with Methyl sulfide of the isooctyl ester of [(carboxymethyl) thio] -

809836/0808

chloroplatinum (II), with the mercaptide molecule part alternatively referred to as chloroplatinum (II) isooctyloxycarbonylmethyl mercaptide can be.

The following complex includes an aralkylthio group in the mercaptide moiety:
Chlorine [(cc-methy Ibenzy 1) thio] platinum (II) ethyl sulfide.

Variants of the first-mentioned mercaptide-butyl sulfide complex in which the mercaptide moiety is the chloroplatinum (II) -tert.-heptyl-mercaptide can be designated by the following complexes with ethyl mercaptoethanol explained, which is a substituted alkyl sulfide, or with Tetrahydrothiophene, a heterocyclic sulfide:

Chlorine (tert.-heptylthio) platinum (II) -2- (ethylthio) ethanol Chlorine (tert-heptylthio) platinum (II) tetrahydrothiophene.

Another platinum compound that is moderately soluble in organic solvents is dibromobis (glycine) platinum (II), [PtBr ₂ (NH ₂ CH ₂ COOH) ₂ ] * and the corresponding dichloro or diiodine complex can also be used. As a further example, better solubility in suitable organic solvents with another diamine complex, dichloro-bis (aniline) -platinum (II), [PtCl ₂ (C ₆ H ₅ H ₂ ) ₂ ], can be expected.

An example of another type of soluble platinum compound is the etherate of platinum (IV) chloride with isopropyl ether, PtCl ^ .0 [CH (CH ₃ ) ₂ ] ₂ .

Another useful platinum (IV) complex is platinum (IV) acid (hexahydroxyplatinic acid), H ₂ Pt (OH) ₆ , which can easily be dissolved in an aqueous organic solvent medium including a non-volatile organic solvent such as 2- Aminoethanol or 2,2 ^I- iminodiethanol, is soluble. By dissolving 27.6 kg of platinum (IV) acid in a mixture of 8.3 kg of 2-aminoethanol and 43.6 kg of water, a 22.6% by weight platinum solution is obtained.

, 809836/0809

Although the theoretical mechanism by which "the improvement in surface area and other criteria of activation of graphite is itself not part of the present invention, it is believed that this improvement is produced by the catalytic activity of small amounts of elemental platinum generated in the exposed surfaces of the graphite during the firing or oxidation treatment.Usually, the platinum is used on the graphite for activation in amounts of about 75 to 2000 ppm based on the weight of the graphite particles, or above 0.004 and conveniently about 0.02 mg The platinum remains stable in elemental form in the presence of oxygen and retains its catalytic activity and results in the desired, selective oxidation at localized points, whereby graphite surfaces at elevated temperatures (generally below about 900 ⁰ C) and during short treatment times can be generated in the presence of oxygen, with minimal weight loss of graphite. It is believed that the presence of platinum facilitates the formation of fine, etched holes or depressions or pores, whereby the desired, highly effective surfaces are produced. During the initial heating, the volatile solvents are driven off and then all or some of the non-volatile solvents are evaporated or decomposed, thereby removing the solvent medium. Upon further heating, the platinum-containing compound or complex is decomposed along with film formers and any residual organic constituents of the coating composition, and the platinum metal remains in the desired dissemination form, which can be quite sparse on the graphite surfaces. A. further heating-in the presence of

809836/0809

Development of a larger surface through the preferential oxidation under the influence of and in the vicinity the small platinum deposits is caused. In general is facilitated by the presence of platinum, which is distributed on the surfaces that are heated, the oxidation, whereby there is weight loss when some graphite is burned off, on and near the surfaces. Although this weight loss can only occur in small proportions, since it is much greater than the loss would be if untreated material were heated at the same temperature for the same time, unless the temperature is increased.

The following examples illustrate the invention.

example 1

The graphite material used is granular or granular graphite (Union Carbide Corp., quality BB-6) and contains about 75% by weight particles with a size of -1.68 + 0.84 mm (-10 + 20mesh in the Tyler Sieve row), about Λ8% larger than 1.68 mm (10 mesh), whereby the main amount, expressed by the weight, passes through a 2.38 mm (8 mesh) sieve and the remainder through a 0.84 mm (20 mesh) sieve passes through it. The material is again sieved to -2.38 + 1.00 mm (-8 + 16 mesh) to remove oversized particles and powder. A particulate material is obtained which is substantially free of powdery fines and in which the particles have diameters (substantially in the absence of acicular particles) mainly in the range of 1 to 5 mm, ie of the order of 2 mm, and have a specific diameter mainly in the range from 1 to 2.5 mm. The ash content of the graphite material is less than 2 Q&W% and generally much less in the range of 1 to 1.3%.

809836/0809

The soluble platinum compound selected for coating the graphite resin is platinum resinate (platinum sulforesinate), made from sulfurized balsam reacted with a platinum salt dissolved in a mixture of non-volatile, essential oils. 14 g of this solution, which contains 12 % by weight of platinum metal (1.68 g of platinum), are mixed with 10 g of gilsonite, 250 g of benzene and 50 g of toluene. The benzene and toluene are volatile solvents that are added to lower the viscosity, improve the ability of the solution to wet the graphite surfaces, and to enable a weaker solution to be used. The gilsonite results in a viscous, asphaltic film former. It is first dissolved in warm benzene with stirring and then the resinate solution and the toluene are added with stirring. The final solution is kept in a glass bottle with a stopper. . . -

A total of 1836 g of graphite are impregnated with 100 g parts by adding about 100 g of the granulate to a Separating funnel is in a vertical position and the solution is poured onto the mass of graphite particles until it is complete are covered with the liquid. After a residence time of 5 min, the excess solution is poured off and poured into poured back the glass bottle for reuse. The moistened, coated graphite is in a glass bowl placed in a hood so that the volatile solvents can evaporate at ambient conditions. This method is repeated with successive pieces of graphite, the total amount of which is 277 g of solution and 1.43 g of platinum in the Contains platinum resinate. The calculated platinum load of the graphite corresponds to 780 ppm platinum metal.

The dried and coated graphite is placed on ceramic racks in layers about 0.6 to 1.2 cm thick and the layers are slowly placed in an electrical

809836/0809

see muffle furnace, which is preheated to 60O ⁰ C, moving. The decomposition of the resinate coating, leaving behind the desired, small platinum metal deposits, which are distributed on the graphite surfaces, takes place rapidly when temperatures approaching approximately 300 ^° C. are reached and vapors are formed. The oven door is then closed and an oxidizing atmosphere is maintained in the oven by continuously blowing air into the oven through a 0.6 cm ceramic tube. Every hour the graphite grains on each rack are shaken so that the particles come from the bottom of the rack onto the surface of the sheet. After 3 hours at 600 ^° C., the weight loss in graphite is about 1B% _t and its surface area

ρ ρ

has increased from less than 1 m / g to 6.2 m / g. It can be seen that atmospheric oxygen is expedient for Used to carry out oxidation during heating but other sources of gaseous oxygen can also be used.

A muffle furnace was conveniently available for this process. Alternatively, a tunnel furnace can be used to advantage and the coated graphite can be transported through the furnace in thin layers on a conveyor. It is furthermore advantageous to use a continuous rotary calcining device in this heating method, in which the heating which is necessary for carrying out the method according to the invention can be carried out while the furnace is kept at a temperature in the range from 600 to 800 ^° C., wherein the coated graphite particles generally pass through the furnace in less than 1 hour. However, if the heating is carried out in order to raise the temperature of the surface parts of the coated particles very quickly, care must be taken to ensure that a sufficient residence time, for example at least 10 to 20 minutes, is ensured during

809836/0809

the surface temperatures rise to about 3OO ° C, so • Avoid burning off the coating too quickly and thus the solvents and the decomposition products of the organic material in the coatings in a suitable manner vaporize and be released.

Instead of the soluble platinum compound used in this example, a halogenoplatinum (II) mercaptide sulfide complex containing the same weight of platinum metal can be used with equivalent results. It is thus possible in a similar example, the isooctyl ester of [(carboxyethyl) thio] -chlorplatin (II),% platinum complexed with methyl sulfide, in an about 25 wt. Toluene solution containing use, the essential as well as a solvent carrier oils, turpentine oil and gilsonite in Benzene solution for application contains, forming a suitable platinum-containing film on the graphite particles. Care must only be taken to ensure that a uniform dispersion is achieved on the graphite surfaces. After some of the more volatile solvents have evaporated, the heating stage is stopped and the coated film is burned off with decomposition of the mercaptide-sulfide complex, leaving elemental platinum on the graphite surfaces. Subsequently, as described above, heated at 600 ⁰ C.

Example 2

Numerous experiments were carried out and the results are listed in Tables I and II below in order to assess the influence of reaction variables such as the oxidation time (heating time in hours), oxidation temperature (heating time in ⁰ C), the type and amount of noble metal in elemental form Coating (ppm of metal that comes from the coating solution used, based on the original weight of the graphite), the weight loss of the graphite, based on its original weight (% loss) and the specific

809836/0809

Surface area of the product in a / g, determined according to the standardized BET method, to be explained. The weight losses are listed for the successful tests between about 3 and about 40 % by weight of the graphite particles to be treated, while in one case slightly more than half the weight was lost. In these experiments, the preparation of the solution of the noble metal resinates, the coating of the graphite and the firing or oxidation "took place as in Example 1.

However, experiments 1 to 12 listed in Table I were carried out only with the heating stage using uncoated graphite particles. From these experiments it can be seen that the uncoated graphite, the surface of which is 0.9 m ^ / g before heating, could not be improved to a surface of over, for example, 3 m / g, even when heated in the presence of air at temperatures as high as 850 ^° C., or during times which exceed 6 hours, and even in experiments 10 and 11, which ^{were carried out at 700 °} C., graphite weight losses occurred that were significantly greater than 50 °. Additional tests in which graphite particles coated with precious metals in addition to or in addition to platinum were used are also listed in Table I and are explained in more detail below.

.809836 / 0809

metal Metal- ■ 21 - T ΘΕΌ. 2809027 before _o in excess weight Table I. ⁰ C " m ² / * Vsr- add; Opr.i warming Weight surface 0.9 SUCh no Time 550 loss 0.9 Mr. U H 600 % 1.3 1 Il no 700 none 1.5 2 Il 1 700 1.1 1.7 3 Il 1 700 1.8 2.0 4th Il 0.5 700 5.7 2.3 Il 1 700 11.7 2.4 6th Il 2 700 22.1 2.7 7th Il 3 700 31.4 2.8 8th Il 4th 700 39.7 2.7 9 Il 5 850 48.4 1.0 10 Il 5.5 600 53.1 2.7 11 Pt / Ag 390/400 6.5 600 62.2 3.0 12th Pt / Ag 260/530 1.5 600 15.0 3.0 13th Ag 680 3 600 22.8 1.8 14th Au 785 5 600 26.1 2.0 15th Ir 715 3.5 600 31.0 2.2. 16 Ir 715 3 600 4.5 1.8 17th Pd 920 3 600 4.0 2.6 18th Pd 920 5 600 6.0 1.8 19th Pd 1120 3 600 4.5 2.3 20th Rh 790 23 600 28.2 3.2 21st Ru 1185 4th 5.5 22nd 3 6.2 23 3 5.8

With platinum distributed on the graphite surfaces, however, surfaces of at least about 3 & / s easily become acceptable with. Get weight losses. Illustrative examples are given in Table II. Runs 24 to 30 give surfaces of 3.2 to 6.2 m / g with moderate weight losses at an oven temperature (except run 25) of 600 ° C, and the preferred method is obtained by these runs (except run 25) of 600 ° C the

809836/0809

3Λ

Attempts 25 and 26 _? in which the heating took place for less than 1 hour or for only 1 1/3 hours) explains weight losses in the range from about 6 to 25%, so that a surface area of at least about 4 m 2 / g is obtained. The results of Example 1 are listed as Run 30 in Table II.

In experiment 25, the influence of increasing the heating temperature was tested. This experiment is comparable to experiment 24, using the same amount of platinum, but the temperature was increased from 600 to 750 ^° C. and the heating was reduced from 0.9 h performed. Although weight loss is about the same as in experiment no. 28, in which more dispersed platinum was used, and h at the 4.5 was heated at 60O ⁰ C, the surface 25 in experimental reached only 3.3 instead of 6.1 m / g. The reason for this lower surface area with comparable weight loss in test 25 is not known with certainty. However, one may speculate that a catalytic burning and etching takes place selectively to localized sites, predominantly in Erwärmungstem- 'temperatures above about 500 ⁰ C, and good to about 600 ⁰ C. However, when the temperatures in the 700 to 800 ° C range to rise It is possible that random thermal oxidation over the entire surface increases at higher temperatures and exceeds localized catalytic oxidation with its caustic effect, so that similar weight losses are associated with the decrease in net surface area. In any event, a comparison of Runs 12 and 25 shows that when distributed platinum is present, the heating temperature and time can be adjusted to obtain beneficial improvements in surface area for a given weight loss with minimal heating time.

809836/0809

For a further comparison with experiments 12, 2h and 25 and again using 152 ppm of platinum, the particulate graphite is heated to an even higher temperature of S5C ° C for only about half an hour, so that the same weight loss is obtained, if possible, as it occurs in attempt 25. Under these conditions, the surface area increases sharply, but it does not reach 3 m / g. This can be explained by the assumption that random thermal combustion masks even more the localized caustic effects attributable to catalytic oxidation. Heating temperatures in the range of about 500 to SOO ⁰ C with suitable adjustment of the amount of used platinum and the heating time in correlation with the specific temperature gives an optimum balance between the weight loss and the increase in the surface. Within limited ranges of platinum loading and temperature, a shorter heating time can be compensated for by a higher heating temperature for a given, approximate weight loss and surface area. "As already suggested, it may be possible to carry out the heating quickly and at relatively high temperatures in suitable furnace devices , in which temperatures above 800 ^° C. are reached for relatively short times without excessive weight loss in order to produce high surface areas. The person skilled in the art will be aware that different graphite materials have different microscopic structures, depending on their source and the manner of their manufacture and possibly from the inclusion of binders or other ingredients such as in molded graphite products or forms. These differences can affect the heating results, also to some extent by the ease of access to air or oxygen s to the graphite surfaces are influenced, regardless of whether the graphite is in coherent or particulate form. The optimal temperature can also be determined by such

809836/0809

Factors such as the particular structure of the furnace and the charging device and the condition of the graphite mass during heating, as well as the exact temperature-time program during heating, can be influenced. Determination of the maximum or preferred temperature must be left to one skilled in the art, to which the above explanations can assist, and may require some preliminary experimentation for a given material and furnace installation and because of the desired properties of the activated graphite. In any case, from the values given below, it appears that many graphite materials ^{can be heated to at least 850 or 900 °} C. for short times without uncontrolled burning or ignition occurring, even in the presence of that which is distributed on the surfaces Platinum.

The following explains the results of Table II. In the experiments 31 and 32, the Oxentemperatur to 525 ⁰ C was lowered, and the heating time was to get too short _T to a threefold increase in the surface, despite the higher deposition of platinum. In Experiment 33, which was carried out at the same temperature, a substantial improvement in the surface was obtained with acceptable weight losses, but the heating had to be carried out for almost a full day in order to obtain these results. A relatively high platinum loading of 1610 ppm was used in all three experiments.

An even higher platinum loading of 1740 ppm was used in experiments 34 to 36 in order to explain the lower heating time, which can suitably be 60O ⁰ C for the larger amounts of platinum. In experiment 34, a surface area of 6 m / g was obtained in just 1 1/3 h with a weight loss of less than 15% . Even higher surfaces were found in tests 35 and 36 when heated.

809836/0809

Measurement times of 5 ms 5 h, but with greater weight losses of up to about 40%. However, such weight losses in the range of 5 "to 4θίί and especially in the neighborhood of 2.5 to 40% may be suitable for some applications, e.g. when the graphite used is relatively cheap and the resulting activated graphite is intended for a specific end use, in particular, when surface areas of 7 m / g or greater are achieved, however, Runs 28-30 and 34-36 show that when a loss of at least about 10% by weight of the graphite particles is acceptable,

a surface area of at least about 6 m / g is obtained.

Other examples listed in Table II include Runs 37 and 33 in which weight losses of some over 6% result in surfaces over 4 m / g, and test no. 39, in which a weight loss is tolerated well over 10%

can be obtained, obtaining a surface area substantially above 6 m / g, as will be described below. It is further stated that may be obtained in Experiment 38, in which a different, particulate graphite material and 340 ppm platinum are used, a similar loss of weight and a somewhat higher surface in 2.5 hours at 55O ⁰ C as in attempting 27 in 3 h at 600 ^° C. with a similar platinum loading of 382 ppm.

With regard to the heating at temperatures below about 600 ° C appears to be the particulate material which has been used in the tests 24 to 36, requiring a temperature of about 500 ⁰ C of Experiment 33 or above to the desired minimum surface in a practical heating time to result, although runs 34 to 3β suggest that e ±, s increase in platinum loading to over 1700 ppm and even as high as 2000 ppm produce a surface area over 3 m / g in a relatively short time at a temperature of 525 ° ^C C or something lower allows. Open minded-

809836/0809

clearly there are other inactive graphite materials as used in experimental 3S -were that for heating at temperatures in the range of about 500 to 55O ⁰ C are suitable with very low platinum loadings, and during periods of several hours or longer, to acceptably high surfaces obtain. A temperature of about 500 to 800 ° C is preferred for the heating process.

The use of air at standard atmospheric pressure results in a partial pressure of oxygen of only a little over 2 at. The person skilled in the art is familiar with the fact that the oxidation, the during heating in the vicinity of the graphite surfaces deposited platinum takes place at a given temperature is accelerated if one considers the partial pressure of the oxygen that prevails on the graphite surfaces is increased. This can be achieved, for example, by something pure Adding oxygen to the air added to the graphite body during heating. With many heating processes the effective concentration of oxygen on the graphite surface is increased more expediently by using the Pressurizes device. Air with a pressure of 2 at will have an oxygen partial pressure of about 0.4 at, while the pressure of dry air only needs to be increased to 5 atm in order to increase the partial pressure of oxygen above 760 mmHg (1 at) to increase. Such an increase in partial pressure of oxygen becomes a corresponding increase in weight loss and the surface result when a given graphite material with a given amount of platinum is distributed on its surfaces, is heated to predetermined temperatures for predetermined times.

The heating can be carried out at elevated, but lower temperatures, which are significantly below 500 ⁰ C, as dictated by the reaction kinetic values, a desired increase in the upper

8Q9836 / 08Q9

- ^ - 2809Q27

area in a time of several hours or even less than 1 hour, if you have higher concentrations of oxygen or air under substantial pressure is used. Of course, rcu3 nan carefully take care one excessive or uncontrolled burning or even a To avoid ignition of the graphite by keeping the temperature, to which the material is heated, in terms of the Partial pressure of the available oxygen is limited.

In experiment 37, the influence of heating at 600 ° C. was determined using somewhat larger graphite particles with a relatively small amount of platinum distributed thereon. The available graphite (Union Carbide Corp. Grade BB-7) has the approximate particle size distribution, expressed by weight, of: -3 + 4 mesh, 57 pounds; -4 + 3 mesh, 42? O, about 3/4 % passes through an 8 mesh screen. Only the fraction that passes through the 4 mesh sieve, but gröi3er than 8 mesh, is used to obtain a particulate material, the public in vres is free of powders and oversize particles and the diameter predominantly in the range 1-5 mm and more specifically predominantly in the range from 2.5 to 5 mm. This -4 + 8 mesh fraction has an effective surface area, determined according to BET, of about 0.9 m / g before the treatment. After 4 hours of heating at 600 ° C with a platinum loading of 132 ppm and a weight loss of 6.3 / 4, the surface area increased to 4.4 m / g, very similar to Experiment 24, where smaller particles were used. The following assignments apply between mesh and mm: 3 mesh = 6.6 mm (estimated); 4 mesh = 4.75 ras; 8 mesh = 2.38 mm.

Experiments 33 and 39, in which a different particulate Graphite material was used are explained below in connection with Example 6

t.

809836/0809

In all tests 24 to 30 and 33 to 39, a mass of graphite in the form of a particulate is obtained Mass with surfaces created by varnishing the mass in presence of elemental platinum, which is distributed on the surfaces, with substantial burning off of the graphite the surfaces and with a residue of the platinum spread thereon were activated. The particulate Graphite material with particle diameters mainly in the range of 1 to 5 mm has a surface area of at least about 3 m / g and has, distributed on the particles, between 75 and 2000 ppm elemental graphite.

The influence of the other noble metals, including the use of a coating containing a silver resinate as well as a platinum resinate, is illustrated by Experiments 13-23 listed in Table I. In only three of these tests the surface area reaches 3 m / g and in tests 14 (platinum and silver) and 15 (silver) the weight loss exceeds 25% with the desired improvement in the surface area only at the edge. In tests 16 to 18, in which gold or iridium are used in substantial proportions, only a slight improvement in the surface is obtained after heating at 600 ° C. for 3 to 5 hours. Palladium is checked in the tests 19 to 21, and one obtains a surface area of only 2.6 m / g after 23s tündigem heating at 600 ⁰ C with a weight loss of 28.2%. It is likely that the palladium deposits will be oxidized when the heating time and temperature taken together reach a level sufficient to result in a substantial amount of oxidation and that the oxidized palladium will not function properly as a catalyst to produce the preferred To obtain oxidation «In experiment 22, in which rhodium is used at the same heating temperature, the surface is also only poorly improved. In the experiment 23 _s with the ruthenium in relative

809836/0809

a high proportion is used, an acceptable improvement is obtained in the surface; this experiment can be compared to experiment 27, in which less than a third so much platinum, expressed by weight, and the the same heating time and temperature can be used, with a surface area of 5 a ~ / g and only a moderate Weight loss receives.

metal metal Tabel II Temp. Weight Upper Ver in about weight Warming ^ ° c " loss area search train; ppm Time 600 % m2 / # No. Pt 152 H 750 9.6 4.8 24 Pt 152 5 600 17.4 3.3 25th Pt 382 0.9 600 3.3 3.2 26th Pt 382 1.3 600 10.3 5.0 27 Pt 382 3 600 17.5 6.1 28 Pt 760 4.5 600 16.5 6.0 29 Pt 780 3 525 18.0 6.2 30th Pt 1610 3 525 3.0 1.8 31 Pt 1610 1.2 525 3.7 2.6 32 Pt 1610 3.2 600 13.2 3.3 33 Pt 1740 23 600 14.8 6.0 34 Pt 1740 1.3 600 33.3 7.0 35 Pt 1740 3 600 38.4 7.3 36 Pt 132 4.7 550 6.3 4.4 37 Pt 340 4th 600 8.3 5.7 38 Pt 340 2.5 53.0 9.0 39 3

Examples 3 to 5 relate to the preparation of granular catalysts using graphite substrates. A wide variety of methods and materials are catalytic for making catalysts using of active precious metals and base metals available on substrates with suitably high surface areas, whereby the choice of the type. and the concentration of the materials from the

809836/0809

rend reaction "under certain conditions and by economic Depends on factors, as is known to the person skilled in the art. The following examples serve to explain »

Example 3

This example illustrates the preparation of a platinum-graphite granular catalyst containing nominally 0.88% (8800 ppm) platinum by weight. The activated graphite catalyst support is produced as described in Example 1 and has a specific surface area of 6 m / g _o

427 g of graphite carrier are placed in a laboratory-scale glass coating pan. "Platinum resinate dissolved in a carrier of essential oil, as described above" (31.8 g at 12? O platinum) is mixed with 146 g of benzene and 30 g of toluene, and the resulting Solution is poured onto the graphite in the rotating coating pan. After mixing for 1 min, the coated and moistened graphite is transferred to a glass dish in a fume cupboard », The granules are occasionally stirred with a spatula to accelerate the evaporation of the solvents * The impregnated graphite is then further placed in a mechanical convection oven at 100 ⁰ g dried for 30 min. The temperature in the furnace is then increased in 90 min to 300 ⁰ C, and the granulate is 3.0 · min at this temperature for decomposition of the resinate and held for evaporation of the solvent without weight loss of the graphite * 'The furnace is then cooled at 100 ⁰ C and the catalyst is bottled.

The used for the production of the activated graphite * Small amounts of platinum remain on the graphite. If this platinum is not removed, such as by leaching with acid in a manner known per se, it contributes to a small extent

& 09.-836 / O8O9

uo

or trace amounts to the platinum or other catalyst metals which are subsequently incorporated into the catalyst, vrLe in these examples.

Example 4

This example explains the manufacture of a bimetallic noble metal catalyst using a graphite substrate. The nominal metal content of the finished catalyst (in addition to the much smaller amount of platinum used in the activation treatment) is 1.8 wt% palladium and 0.79 wt % gold. Granular graphite (from Union Carbide Corp., grade BB-7), produced as indicated in Example 2, in test 37 (Table II) with a selective oxidation at 600 ° C. using 132 ppm of platinum, distributed over the Graphite particles, used to achieve a surface area of 4.4 m / g.

The graphite support (562 g) is placed in a laboratory-scale coating pan. A gold resinate dissolved in a mixture of essential oils (38.1 g with 12 ^ gold) and a similar palladium resinate solution (116.4 g with 9% palladium) are dissolved together in 100 g of toluene. The resulting solution is poured onto the graphite contained in the rotating coating pan, then mixed for 1 minute and then the rotating pan plus its contents are heated by placing a heating lamp over the pan. The heating is continued until a sticky, granular mass is obtained. The coated granules are placed in a ceramic rack. The granules in the frame is heated for 15 minutes in a mechanical convection oven at 100 ° C dried, in 60 min to 300 ⁰ C, held for 60 min at 300 ⁰ C tmd then cooled to ambient temperature. 'The catalyst is then filled into bottles.

009836/0809

example

This example illustrates the preparation of a base metal catalyst on granular graphite. The nominal metal content of the catalyst is 1.0 oji iron. The particulate graphite support (198 g) is placed in a laboratory-scale coating pan. An Eisanresinatlösung (16.8 g with 11.9% iron) is dissolved in 50 g of toluene. The resulting solution is poured onto the graphite in the rotating pan, mixed for 1 min and then the mixture in the pan with heating lamps to evaporate the Toluene heated. The granular mass is then placed on a ceramic rack in a mechanical convection oven. The oven is ^{heated to 350 °} C. in 60 minutes and held at 350 ^° C. for 30 minutes. Then the rack is removed from the oven. After cooling, the catalyst is filled into bottles.

Example 6

Another graphite material is based on its use either in particulate form or as a body or plate tested in non-particulate form (i.e. in coherent form). This graphite material is commercially available in the form of molded, rectangular blocks, 15 cm 15 cm χ 5 cm thick (Pure Carbon Company, Inc., St. Marys, Pa., Grade FC-36). This material is stated to have a low ash content of about 0.1% by weight and a specific surface area of has as little as 0.3 m / g, indicating that the material is very inactive. To confirm that this material is either is suitable in particulate or in coherent form for activation by the method according to the invention, a block of the material is crushed and by grinding in a mortar the size is reduced. After seven will a fraction of -2.38 + 1.41 mm (-8 + 14 mesh) was obtained. A particulate material is obtained in this way. Own the particles mainly diameters in the range from 1 to 5 mm, comparable

8 09836/0809

with the dimensions of particles used in the experiments described in Examples 1 and 2.

The surface of the particles thus obtained by grinding in a mortar and sieving is determined by BET measurement; it is 0.4 in / g. A mass of these uncoated particles with a glossy, dark appearance is ^{heated to 60O 0} C for 3 h in the presence of air. The subsequent measurement of the weight and the activity of the mass of particles treated in this way shows a weight loss of 5.5% and a surface area of 1.4 m / g. The results of this experiment can be compared with experiments 1-4 listed in Example 2 and Table I.

A platinum resinate gilsonite solution in benzene and toluene, as described in Example 1, using 14.0 g resinate containing 1.68 g platinum, is tested for the influence of heating this graphite material while wearing elemental platinum on its exposed surfaces. 10, Og Gilsonite, 250 g of benzene and 50 g of toluene. An equal weight of additional benzene is added to a portion of this platinum solution in order that this particular coating process can be carried out in a suitable manner. A mass of crushed, sieved particles of FC-36 grade graphite weighing 15.22 g is coated with an excess of the resulting dilute solution and then the solution is allowed to drain. There remain 2.0 g of solution containing 5.2 mg of platinum. After drying at room temperature, the coated graphite is heated to remove volatile and non-volatile solvents and to decompose residual organic material. 340 ppm of elemental platinum remain, distributed on the surface of the particles, and ^{heating is then continued for 3 hours at 600 °} C .; a mass of particles with a matt, dark appearance is obtained; the particles formed from slides weigh 7.15 g; this corresponds to a weight loss of 53.0%. This same particulate

S09836 / 0809

Material has a greatly enlarged surface of 9.0 m / g. Another test of the particles with a surface area of 0.4 m / g is carried out by similar coating with the same solution. A platinum loading of 340 ppm is obtained. Subsequently, the heating stage with access of oxygen 2.5 h "is carried out at 55O ⁰ C. In these treatment conditions, the weight loss is only 8.3% and the measured surface area is 5.7 m / g. This experiment is for comparison in Table II listed as experiment no. 38, while the results obtained on heating the platinum-containing particles for 3 hours at 60O ⁰ C are listed as experiment no. 39 in Table II.

Of these two tests, test 38 is carried out for 2.5 hours with a heating temperature of 550 ° C. and can be compared with tests 27 and 28. Experiment 39, in which the heating took place for 3 hours at 600 ° C, results in a weight loss of a little more than 50%. However, a material with a significantly higher surface area is obtained. that the material that the FC-36 was obtained by crushing and sieving the coherent graphite material quality, is more readily activated something or _s is so that a lower platinum loading or shorter heating times and lower heating temperatures, or both, sufficient a given surface with the accompanying weight loss to surrender.

Example 7

If a coherent block or a plate of graphite in the catalytic heater is used, it is important to note that the shaped graphite body has a good heat stability, which ensures the dimensional integrity at the operating temperatures of the heating device, normally in the range of about 200 to 30O ⁰ C lies, owns. Furthermore, it must be noted that there is no weight loss in these

809836/0809

MM

these conditions occurs. To confirm that the aforementioned FC-36 quality molded carbon blocks If they have the required stability, two smaller panels are machine-made from the massive blocks. Man produces one plate, which is designated with A and has the dimensions 62j2 χ 49jO χ 6.1 mm and a weight of 31.39 g, and another plate, labeled B. and the dimensions 60.9 x 49? O χ 6.1 mm and a weight of 30.73 g. Plate A is treated with the platinum resinate solution from Example 1 by

2
area 30.5 cm area on one side of the plate applies an amount of platinum solution that weighs 0.48, which gives a sweeping of 0.08 mg elemental platinum / cm of coated surface. Plate B is not treated with the platinum resinate solution. Both plates A and B are placed in an oven at 500 ⁰ C. The furnace is continuously purged with air to maintain the oxidation conditions. After 17 hours, the graphite plates are removed from the oven and weighed. The weight loss of plate A is only 2.9 / 6 and that of plate B without the platinum coating is even less, ie 1.3 %. No distortion or otherwise noticeable damage to the plates is observed. Since 500 ^° C. would be excessively high for the operating temperature of the catalytic heater in which the activated graphite plates are used, this graphite material is considered suitable and is considered to be a material with good stability.

Example 8

Another plate is used to create a graphite plate for testing in a catalytic heater Machine made from a solid graphite block quality FC-36 with the dimensions 7.0 χ 7.0 χ 0.64 cm. A square portion, 6.0 cm (2.375 inches) on one side at the center of the plate, with an area of 34.8 cm

S09836 / 0809

(5.64 sq.in.) is perforated by making 343 holes with a Drill 0.08 cm (1/32 inch) in diameter into this area with the holes equidistant from one another leaving an exposed treatment part which is 34.7 cm (5.4 sq.in.) in area. The weight of the perforated plate is 56.0 g. The fora and the dimensions the plate are only used for convenience chosen so that they are in a catalytic Burner can be used.

The square treated on one side of the plate is treated as follows. The platinum resinate gilsonite solution in 250 g benzene and 50 g toluene, prepared as in Examples 1 and 6, is brush applied to one side of the 6.0 cm (2.375 sq.in.) perforated exposed area of the panel , then it is ^{dried for 15 min at 100 °} C. and then the plate is cooled. The coating, drying and cooling are repeated so that a total platinum metal loading of 140 mg is obtained, which corresponds to 250 ppm based on the weight of the plate, or more relevant 0.40 mg platinum / cm coated surface, calculated from the weight of the actual applied platinum resinate solution. The coating density in weight per unit area refers to the gross geometric coated area, calculated from the linear, planar or obvious dimensions of the exposed areas to which the coating material is applied, and not to the BET surface areas, measured by adsorption processes through which the microscopic surface irregularities or -porosity is taken into account. The thus coated plate is then 3 h at 600 ° C in an electric muffle furnace oxidized, wherein the exposed, coated surface faces upwards and is exposed to the air in the oven "After 3 h is the weight loss k, ~ '\% for the entire 6.4 mm thick plate; this corresponds to 26% by weight of a surface part of the 1 mm thick plate,

809836/08 0 9

-sn-

which extends downward from the treated surface part of the Plate extends, Due to the treatment, the appearance of the coated, exposed surface has changed from ei-Π33 changed the shiny appearance to a matte black color, indicating that the surface has been etched and has been activated and that porosity has been created and that the effective area of the surface of the plate has been improved or enlarged.

The above-mentioned weight of 0.40 mg platinum / cm, the deposited on the exposed surface of the plate for heating activation can be significantly lowered are, in fact, to about 0.02 mg or less platinum / cm of exposed surface (calculated from the linear or apparent dimensions of the coated areas). This is illustrated by the ease with which the heating treatment to produce high surface values is achieved, in the experiments explained in Example 6 on the same material which was converted into particulate form and was coated with 3 ^ 0 ppm platinum. With particle sizes in ^ General size range of particles used in the experiments of Example 6 with particle diameters in of the order of 2 mm is the total surface loading of such particles when they weigh 75 ppm Carrying platinum (based on the total, original weight of the particles), roughly equivalent to the platinum loading, determined as weight / surface unit, of 0.004 mg / cin apparent or geometric surface. At least about

Platinum 0.004 mg / cm2 should be used for activation treatment be used.

Similarly, the heating should be carried out for a sufficient time and at a sufficiently high temperature so that there is a weight loss of at least about 3% and preferably from about 6% up to about 25% or

809836/0809

up to about 40% or even higher. Such weight loss can be tolerated if a solid block or plate with high mechanical strength is used which, after treatment, serves as a catalyst for extended periods of use. The percentage weight loss is based on the original dish of the activated surface part of the body that extends 1 mm below the treated, exposed surface. A depth of 1 mm is used for the calculation of the weight loss, not only for the sake of convenience in the calculation, but also to indicate that a comparable, effective surface and thus the usefulness as a catalyst substrate are obtained. The weight loss for the particulate graphite can be expressed as a percentage of the total weight of the particles, and for a graphite surface it can be expressed as a percentage of the weight of the exposed surface layer of a specified thickness. Therefore, if the thickness of such a surface portion of a block or a plate than 1 mm is assumed that the effective surfaces are roughly equivalent for a given weight loss value _s that the treatment "is carried out with equivalent platinum loadings and heating times and temperatures on the assumption It may be possible ,, the surface of the. The plate can be estimated by cutting out a small part of the plate, including part of the activated surface, and exposing only that part of the surface to the BET, surface measurement, taking the weight of a 1 mm thick plate below the measured part of the plate as a weight basis Surface is «The surface of the activated plate surfaces can also be roughly determined by scratching a surface layer to a depth of about 1 mm or a little less and performing the B» ET surface measurement on the resulting particles.

809836/0809

HZ

Example

This example illustrates the manufacture of a catalyst plate using as a substrate a plate with a treated or activated surface portion with perforations in it and below, made according to Example 8. More of the platinum resinate in a mixture of essential oils but without gilsonite and volatile ones Solvent, is brushed onto the treated surface, and the plate is again ^{heated in a mechanical convection oven at 30O 0} C for 30 min. After cooling, an additional coat of the same resinate is applied, followed by the same heating and cooling cycle. After this further coating, the calculated platinum loading is 1900 ppm, based on the weight of the graphite plate, or, more precisely, 2.9 mg platinum / cm of treated and coated surface.

As previously indicated, a variety of catalyst materials are available available, which can be incorporated into the activated surfaces of a graphite mass, together with procedures for their application., with the activated Surfaces of the graphite mass are produced by the method according to the invention. A finished catalyst is obtained with a very useful large surface area. Such a catalyst can be catalytic at a variety of Reactions be useful, such as in oxidation, reduction by hydrogenation, alkylation, halogenation, etc., in particular when the reaction is carried out in a corrosive medium to which graphite is highly resistant, e.g. in media that are too alkaline or too acidic to use aluminum oxide and other common catalyst supports. Are the catalysts e.g. in the case of catalytic oxidation in general and in particular in the oxidation of carbonaceous material by treating the material in a fluid Shape under oxidizing conditions with a catalyst

809836/0803

used, e.g. in the oxidation of ethylene or propylene to the corresponding oxide or in the burning of fuels, Various other catalytically active materials can also be used in place of the materials are given as examples in Examples 3 to 5 and 9. You can use any precious metals or precious metals or apply mixtures or their alloys to the activated graphite surfaces and work into them, in particular Metals of the platinum group and preferably platinum or palladium or their mixtures as well as gold or silver. Of the Base metals are known in the catalysis art to have useful catalytic activity in various reactions is obtained with a catalytically active metal, in particular with the non-noble transition metals, the two oxidation states «These elements have atomic numbers of 22-31, 40-49 and 72-81 inclusive and can be used as transition metals be classified. Among the useful examples of such catalytically active base metals can be mentioned be: vanadium, chromium, manganese, iron, cobalt, nickel, copper, molybdenum, tungsten and rhenium; among others are Selenium, tin and cerium are also known for their catalytic activity. Mixtures and alloys of these base metals, such as winding chrome or cobalt chrome, are also useful. Under the working conditions, the base metal can be or The base metals can be used as a compound, such as a salt and often as an oxide or as a mixture of base metal compounds or oxides, which may also be present in the form of a mixed oxide compound.

It is thus possible to produce catalysts, for example according to the procedures of Examples 3 and 9 _S using catalytically effective amounts of materials selected from the group of precious metals and base metals, such as just mentioned, and using in particular of at least one metal of the platinum group, in particular "Platinum itself. The use

809836/0809

so

such catalysts for oxidation as described in the flanua-free, catalytic combustion of natural gases, gaseous alkanane and other gaseous fuel-air mixtures takes place, is explained by catalytically referring to two Manufacturers of burners as shown in FIGS.

Referring to Fig. 1, the catalytic burner comprises a conical steel cup with a gas inlet passage 11 to it the apex. The cup is partially full to a depth of about $ 80 of its height with an inactive, granular graphite material or other suitable permeable filler material 12. A 40 mesh per inch steel screen 13 is placed on top of the filling material, and the rest of the cup is covered with a catalytically active, particulate material 14 filled. Gas to be burned and premixed with combustion air can, is passed into the cup through a flexible inlet bore connected to the inlet passage 11.

In Fig. 2 a modified form of catalytic burner is shown. This burner includes a container 20 made of refractory bricks or other suitable refractory material. The upper Part of the container defines a chamber 21 into which one Bottom layer of silicon dioxide glass wool 22 is placed, over which the chamber is filled with ceramic balls 23. Of the The upper edge of the container is bulged so that a support shoulder 24 is created on which a perforated graphite catalyst plate 25 is carried. Gas to burn, preferably premixed with an excess of combustion air, is fed into the container chamber through a passage 26 and a gas inlet tube 27. The container can either have a square or other cross-sectional shape.

809836/0809

Example 10

A granular platinum-graphite catalyst, prepared according to Example 3, is placed in an amount of 28.3 g in a 9.5 mm thick layer and on average about 8 particles deep into the burner shown in FIG. 1 as material 14. Natural gas with the following composition, expressed by the volume 8254 methane, 5% ethane, k% hydrogen, 2% nitrogen and the remainder saturated and unsaturated, gaseous hydrocarbons and inorganic gases, is fed into the burner «The gas is ignited, and the The body can heat up to around 200 to 300 ^° C. through the flame. The gas flow is then slowly reduced to 32 l / h, which causes the flame to die and catalytic combustion of the natural gas in a weak mixture with ambient air, which flows through the burner by natural convection. In the steady state, the temperature above the granulate is about 180 ^° C. The experiment is continued for 60 h and then interrupted,

Beis piel 11

Gaseous fuels, typically the lower alkanes and more generally a fuel selected from the group consisting of: lower alkanes, carbon monoxide and hydrogen, can be burned in a burner employing the activated, granular graphite catalyst, usually with access or premixed with an amount of air well above the stoichiometric amount so that low catalyst temperatures and low exhaust gas temperatures are generated. An experiment similar to that described in Example 10 is carried out in the same apparatus using methane gas from cylinders as fuel. With a methane flow of 32 l / h, a constant or stable surface temperature of 180 ° C is measured again, and the test is stopped after 60 h.

809836 / 08G9

S3.

broke. Using the same burner piping, but with n-butane as the gas supply, an Ico; _; : ante or constant surface temperature of 180 ⁰ C with a flow of - ^; -, 2 1 butane / h obtained. Similarly, tropane or a technical, butylene e.rz. ruling Prorjan from parts of ice. 3 butane can be burned at very low temperatures

Using the same burner and carbon monoxide as the gas feed, the surface temperature in the steady state is 200 to 220 ^° C. with a flow of 17 1 carbon monoxide / h.

Another experiment was conducted using a premixed fuel charge in inlet 15 of 50,000 natural gas and 20,000 air in terms of volume. It was again sat a temperature of 1SO ⁰ C B3I steady state at a flow ~ -one J5o l / h.

Example 12

In another experiment, a similar type of burner to that shown in Fig. 1 was used. 11.3 g of the 0.889a Pt-graphite catalyst from Example 3 were applied to a circular bed 8 mm high and 52 mm in diameter. A mixture of 93 % by volume nitrogen and 7% by volume hydrogen was used. With a gas flow of 240 l / h, a temperature of 110 ^ C was observed in a stable state. This hydrogen-containing gas mixture has the great advantage that no preheating of the layer or initial ignition of a flame is required. To explain this automatic cold start activity, the entire burner ^{beaker was cooled to 10 °} C. and the experiment was repeated. The surface temperature rose to 106 ° C. in 15 minutes and then remained constant.

B 0 9 8: 3 6/0 8 0 9

2 8 Π 9 Π 2 7

Gas mixtures containing hydrogen, as used in this experiment, have great industrial applications and are easily produced in Ga norator en available in the Hanciö-l , for example as "Nitrüneal" generator6ii 'Engelhard Industries, tT3 ^: .-Rark, New Jersey) or as "At &ospusre" generators (Sunbeam Company, Meadville, Pennsylvania). Such gases are known under the name "Aniaßgas" - or "Tempergas" or "Formierungsgas" and are obtained by partial combustion of ammonia gas or natural gas with controlled amounts of air. Depending on the air used in the partial combustion, the hydrogen content can be regulated between 0.5 and 25% by volume, the main component being nitrogen and the gas also containing smaller amounts of carbon monoxide or carbon dioxide.

A similar experiment is performed using an inlet gas mixture of 14 % by volume propane and 86% by volume air. At a flow rate of 170 l / h, a temperature of 260 ^° C. is reached with a constant state.

Example 13

A platinized, perforated graphite plate, produced according to Example 9, is placed on a fireclay body, such as it is shown in Fig. 2, mounted with the treated surface of the plate facing upwards and exposed to the air is. Butane is fed into the heater at a flow rate of 11 l / h and up through the Perforations in the plate passed up to its upper surface. The catalytic oxidation of butane occurs at the treated surface of the plate, which carries platinum with highly effective surfaces. An upper surface nt; j ~ ip era tur of 225 ° C is measured at a constant state, vind the The experiment is interrupted after 8 hours. For the desired tan Fuel feed rates, the plate configuration is chosen so that the perforations are spaced apart

809836/0809 ^

are brought that the access of combustion air is possible while burning: over the main part of the plates surface takes place. At higher fuel flow rates it is preferred to add some air to the fuel feed to mix, so that a complete combustion is ensured; is and that the desired plate temperature or it may be preferred to modify the layout of the perforations, or both. Alternatively can an imperforate treated plate having means (not shown) for directing the fuel-air mixture be used from one edge of the panel closely along the treated, catalytically active surface, the effluent then exiting the opposite edge of the plate.

80983G / 0809 ^ _{0 0R1Q1NAL}

Claims (1)

PATENT ADVOCATES A. GRÜNECKER ΠΡ · _-ΙΝα H. KINKELDEY 2809027 ^W - STOCKMAlR * """... DR-INa -A ₁ ) EiCALTECH) K. SCHUMANN DR RER. NAT - DIPL-FHYS P. H. JAKOB □ IPL-ING. G. BEZOLD DR RERNAT- OIPU-CHEM MUNICH E. K. WEIL DR. PER OEC! Nt ₁ . 8 MUNICH 22 MAXIMIUIANSTRASSE 43 LINDAU Claims 1. A method for activating inactive graphite, characterized in that one a mass of the graphite having an ash content below about 2 Gew.?6 with a soluble platinum compound in solution in an organic solvent medium including a non-volatile organic solvent, the solution is exposed to the deposition on the Oberflädien the graphite mass _9, an amount of the solution contains at least about 0.004 mg elemental platinum / cm surface area, treated, and the graphite mass, which carries the platinum compound, at an elevated temperature with access; heated by oxygen to the exposed surfaces - to remove organic solvent medium and to decompose the platinum compound, leaving elemental platinum dispersed on the surfaces, and the heating is carried out for a time sufficient to produce a weight loss of at least about 3% _t based on the weight of the portions of the mass extending 1 mm below the exposed surfaces. 809836/0809 TELCFON (039) 22 08 62 TELEX 05-29 3BO TELEGRAMS MONAP 2. The method according to claim 1, characterized in that the heating is carried out at a temperature of about 500 to 800 ⁰ C. • "■ o ^v 3. The method according to claim 1, characterized in that that the heating is continued at the elevated temperature for a time sufficient to cause weight loss between about 6 and about 25? o based on the weight of the Parts of the body, extending 1 mm below the exposed surfaces. 4. The method according to any one of claims 1 to 3, characterized characterized in that the soluble platinum compound is a platinum resinate. 5. The method according to claim 1, characterized in that the soluble platinum compound is a halogen platinum (II) mercaptide sulfide complex is. 6. The method according to claim 1, characterized in that after heating the graphite mass, the exposed Surfaces with a catalytically effective amount of a catalyst material impregnated. 7. The method according to claim 6, characterized in that the catalyst material is selected from the group which contains: precious metals, mixtures and alloys of precious metals, the basic metals iron, cobalt, nickel, vanadium, chromium, magnan, copper, selenium, molybdenum, tin, cerium, tungsten and rhenium, mixtures and alloys of these base metals, compounds of these base metals and mixtures of these compounds. 809836/0809 8. The method according to claim 1, characterized in that the graphite mass after heating on its exposed Surfaces is impregnated with a catalytically effective amount of at least one metal of the platinum group. 9. A method for activating a surface of a coherent body made of inactive graphite, characterized in that one a graphite body that has an ash content below about 2% by weight, including a soluble platinum compound in solution in an organic solvent medium a non-volatile organic solvent for deposition on a surface of the body, that of the solution is exposed to an amount of the solution which contains at least about 0.004 mg elemental platinum / cm surface, treated, and heated the body at an elevated temperature with access of oxygen to the surface to remove the organic solvent medium and to decompose the platinum compound, leaving elemental platinum dispersed on the exposed surface, and wherein the heating is continued for a time sufficient to one Weight loss of at least about 3% _t based on the weight of the part of the body extending 1 mm below the exposed surface. 10. The method according to claim 9? characterized in that the heating I
is carried out. that the heating at a temperature of about 500 to 800 ⁰ C 11. The method according to claim 9? characterized, that heating is continued at the elevated temperature for a time sufficient to cause weight loss between, about 6 and about 40? pounds based on the weight of the Parts of the body to yield ^ which extend 1 mm below the exposed surface " 809836/0809 12. The method according to claim 9 »characterized in that the soluble platinum compound is a platinum resinate. 13. The method according to claim 9 »characterized in that after heating the graphite body, the exposed surface with a catalytically effective amount of a catalyst. Sator material is impregnated. 14. The method according to claim 13 »characterized in that the catalyst material is selected from the group which contains: precious metals, mixtures and alloys of precious metals, the base metals iron, cobalt, nickel, vanadium, Chromium, manganese, copper, selenium, molybdenum, tin, cerium, tungsten and rhenium, mixtures and alloys of the base metals, compounds of the base metals and mixtures of the compounds. 15. The method according to claim 9 »characterized in that after heating the graphite body, the exposed Outer surface with a catalytically effective amount of at least impregnated with a platinum group metal. 16. A method for activating inactive graphite, thereby marked that one a particulate mass of graphite with an ash content below about 2 % by weight with a soluble platinum compound in solution in an organic solvent medium including a non-volatile organic solvent for deposition on the surfaces of the particles of the mass of an amount of solution that is at least about 75 ppm elemental Platinum, based on the weight of the particles, contains, treats and. the graphite particles that carry the platinum compound, at elevated temperature in the presence of oxygen Organic solvent removal and decomposition the platinum compound heated, whereby elemental platinum, 809836/0809 splits on the surfaces of the particles, remains, and carries out the heating for a time sufficient to result in a loss of at least about 3% by weight of the particles. 17. The method according to claim 16, characterized in that that the particles mainly have diameters in the range from 1 to 5 mm. 18. The method according to claim 16, characterized in that that the amount of solution deposited on the surfaces of the particles is between about 75 and 2000 ppm elemental platinum, based on the weight of the particles. 19. The method according to claim 16, characterized in that the heating bi
is carried out. that the heating at a temperature of about 500 to 800 ⁰ C 20. The method according to claim 16, characterized in that the heating at the elevated temperature during a Time is carried out, which is sufficient that the particles from the graphite mass, which before the activation, a surface of less than about 1 m / g, after heating have a surface area of at least about 3 m / g. 21. The method according to claim 20, characterized in that the graphite particles during heating between about 3 and lose about 40% of their weight. 22. The method according to claim 20, characterized in that the graphite particles during heating about 6 to about Lose 25% of their weight and that the particles of mass have a surface area of at least about 4 m / g after heating. 809836/0809 23. The method according to claim 20, characterized in that the graphite particles during heating at least lose about 10% of their weight and that the particles of the Mass have a surface area of at least about 6 m / g after heating. 24. The method according to claim 16, characterized in that that the soluble platinum compound is a platinum resinate. 25. The method according to claim 16, characterized in that that after heating the graphite particles, the particles with a catalytically effective amount of a catalyst material are impregnated. 26. The method according to claim 25, characterized in that the catalyst material is selected from the group which contains: precious metals, mixtures and alloys based on precious metals, the base metals iron, cobalt, nickel, vanadium, Chromium, manganese, copper, selenium, molybdenum, tin, cerium, tungsten and rhenium, mixtures and alloys of these base metals, Compounds of base metals and mixtures of compounds. 27. The method according to claim 16, characterized in that that after heating the graphite particles, the particles with a catalytically effective amount of at least one metal the platinum group are impregnated. 28. The method according to claim 25, characterized in that the impregnation step is carried out using a platinum-containing impregnation material to produce a catalyst which contains at least 0.5 % by weight of platinum and has a surface area of at least about 3 m / g. 29J Graphite mass with a surface that is distributed on the surface by heating in the presence of elemental platinum 809836/0809 Surface, with substantial burning of the graphite from the surfaces and leaving the platinum behind on it, has been activated. 30. graphite mass according to claim 29, characterized in that the graphite is in the form of a coherent body made of graphite is present, at least one side thereof having an activated surface. 31. graphite mass according to claim 29, characterized in that the graphite is in the form of a particulate mass, wherein the particles have activated surfaces. 32. Particulate graphite material having a surface area of at least about 3 m / g and distributed over the particles between about 75 and 2000 ppm elemental platinum based on the weight of the particles. 33 Particulate graphite material according to claim 32, characterized in that the particles have a diameter mainly in the range of 1 to 5 mm. 34. A method for the oxidation of a carbonaceous material, characterized in that the material is in fluid form under oxidizing conditions with a catalyst treated in the form of a mass of graphite, which has surfaces that are obtained by heating in the presence of elemental Platinum, distributed on the surfaces, is activated with substantial burning of the graphite from the surfaces have been incorporated into the activated surfaces, a catalytically effective amount of a catalyst material has been. 35. The method according to claim 34, characterized in that the catalyst material is selected from the group 809836/0809 which contains: precious metals, mixtures and alloys of precious metals, the basic metals iron, cobalt, nickel, vanadium, chromium, hangan, copper, selenium, molybdenum, tin, cerium, tungsten and rhenium, mixtures and alloys of the base metals, compounds of green metals and mixtures of these compounds. 36. The method according to claim 34, characterized in that the catalyst material is at least one metal of the platinum group contains. 37. Process for burning a gaseous fuel-air mixture, characterized in that the mixture is treated with a catalyst in the form of a graphite mass, has the surfaces, which by heating in the presence of elemental platinum, distributed on the surfaces, with Significant burning off of the graphite from the surfaces have been activated, wherein in the activated surfaces a catally effective amount of at least one platinum group metal has been incorporated. 38. The method according to claim 37, characterized in that the metal of the platinum group is platinum. 39 · The method according to claim 37, characterized in that the graphite mass is in the form of a coherent graphite body is present, at least one side having activated surfaces. 40. The method according to claim 37, characterized in that the graphite mass is in the form of a particulate mass possesses, the particles of which have activated surfaces. 41. The method according to claim 37, characterized in that the gaseous fuel in the fuel-air mixture is selected from the group including: lower alkanes, carbon monoxide and hydrogen. 809836/0809