DE2831594A1 - CATALYST, METHOD OF MANUFACTURING THEREOF AND ITS USE - Google Patents

Description

PATENT LAWYERS

WUΙΐ STHOFF - ν. PECHMANN - BEHRENS - GOETZ

PROI I SSIONAI. RE ΓΡ. ESENTATIVE I1K PORF. TII E EUROPEAN PATENT OFFICE MANDATAIRES AGKKES PRES l'OFFICE EUROPtEN DES BREVETS

UR.-ING. FRAI'Z VUESTHOFF

DR. PHIL. FREDA TUESTHOFF (1927-I9J6)

DIPL.-ING. GERHARD PULS (l9J2-I97r) DIPL.-CHEM. DR. E. BARBER OF PECHMANN DR.-ING. DIETER BEHRENS DIFL.-ING .; DIPL.-TCIRTSCH ^ -ING. RUPERT GOETZ

D-8000 MUNICH SCHWEIGERSTRASSE

phone: (089) 6620 ji TELEGRAM: PROTECTPATENT telex: j 24 070

1A-51 157

Patent application

Applicant: T R ¥ Ine.

One Space Park,
Redondo Beach,
California 90 278 USA

Title: Catalyst, process for its manufacture and its use

809885/0870

PATENT LAWYERS

WUEoTHOFF-v. PECHMANN-BEHRENS-GOETZ

PROFESSIONAL REPRESENTATIVES BEFORE THE EUROPEAN PATENT OPFICE MANDATAiRES agrees pres l'office europeen des brevets

d ...-. ng. fra, jz v uesi hop.

dr. p: -l. pf.da do. ' stiio ¹ "= (1927-1956) dipi.-ing. gerhard pui.s (1952-1971) dipi ..- ciiem. dr. e. baron von pechmann dr.-ing. dieter behrens dipi ..- ing .; dipl .- ^ irtsch.-ing. rupert goetz

D-8000 MUNICH 90 SCHWEIGERSTRASSE 2

phone: (089) 6620 51 telegram: protectpatent TELEX: 524070

1A-51 157

description

The invention relates to a catalyst material in the form of a highly reactive carbon with at least 0.5% by weight of a metal of the iron group, which is particularly suitable for the production of methane from synthesis gas or from strong gas. The catalyst can be present in non-activated form or in a form activated with hydrogen. The non-activated form is produced by bringing a CO-containing gas together with a disproportionation initiator under such conditions that the metals of the iron group diffuse into the carbon and are at least partially bound on the free carbon deposited on the initiator. This non-activated catalyst is activated with hydrogen. The CO can come from a generator gas from the combustion of coal. In the case of the catalyst according to the invention, free carbon is present as an uninterrupted main phase and one or more metal or iron groups ₍ alloys or carbides thereof are optionally bound with the free carbon as a disperse smaller phase.

809885/097 0

Hydrogen reacts rapidly with a carbonaceous material to form methane-rich gases in which the methane content can be at least 20% by volume, which is an economical method for producing methane-rich gases. The carbonaceous material can be substantially depleted of carbon ₍ without this being at the expense of its high reactivity with hydrogen. The carbon-depleted material can be replenished with carbon by exposing it to CO. So you can alternate methanization and carbon separation, whereby you receives a very economical overall process for the production of methane from generator gas. During this alternation process with high-carbon and low-carbon stage, the carbon-containing material is subject to a transformation into a hydrogen-activated material, which has a higher deposition rate and methanation rate than the non-activated material like it Almost all of the carbon in both the activated and non-activated carbonaceous material can react with hydrogen without causing deactivation in terms of carbon deposition or methanism ation leads.

A wide variety of carbonaceous materials are known and used as pigments, raw materials for coke, adsorbents and the like. One type of carbonaceous material is formed by disproportionation with deposition of carbon from CO in the presence of an iron group-based metal catalyst. "Disproportionation" is understood here to mean reactions that lead to carbon deposition from CO according to the following equations:

809885/0970

2 CO > C + CO ₂

CO + H ₂ ί> C + H ₂ O

In many chemical processes, the formation of such carbonaceous substances by CO disproportionation reactions is a very undesirable side reaction which can also deactivate the catalyst for these processes by carbon deposition thereon. The carbonaceous material so formed has little economic value. It is known that it can react with hydrogen to form methane, which is the main component of natural gas. The known carbon-containing * products, however, resulted in such a slow reaction rate that no economically interesting process could be based on them. Since the methane consumption and demand is always increasing, attempts have already been made. Producing methane from coal, for which a lot of development work has already been done. There is already a synthesis process in which CO + H ₂ is supposed to lead to methane. CO + H ₂ (synthesis gas) are obtained by burning coal in oxygen and steam. Oxygen is generally used instead of air, since synthesis gas for the production of methane should not contain any major proportions of nitrogen because nitrogen cannot easily be separated from the synthesis gas or the methane. A disadvantage of this method is therefore the need for a large and expensive generation of oxygen. _{The CO 2} formed during methanation must also be separated from the CO + H ₂ stream in order to produce a strong gas. This is relatively expensive.

The object of the invention is therefore a method that is highly reactive, in particular with hydrogen to form methane carbonaceous material which is inactivated

809885/0970 " ⁴ "

can or "is already activated with hydrogen by passing hydrogen over the non-activated material. The carbonaceous material according to the invention is a multiphase system in which a carbon-rich main phase and a disperse phase is rich in one or more metals of the iron group, which is at least partially bound to the carbon. The ferrous metal catalyzes the reactions of carbon formation by the hydrogenation of the carbonaceous material. To obtain this catalytic effectiveness, the ferrous metal should be in an amount of at least 0.5 wt .- ^, based on the total weight of the At least 1% by weight is preferred. In the non-activated carbonaceous material, the ferrous metal should preferably make up 1 to 3.5% by weight h and moles of carbon reach when the carbon is mixed with hydrogen at a temperature of 550 ⁰ C and a pressure of 1 atm (1 ata) and the minimum feed rate for hydrogen is 2 moles per hour and mole of carbon. This reactivity towards hydrogen is a special property of the material according to the invention. It is much higher than that of other forms of carbon. The material of the invention retains the high reactivity even when it is substantially depleted or enriched in carbon. Under certain conditions, water can have a detrimental effect on reactivity, especially the rate of methane formation. Accordingly, hydrogen should contain <1% by volume at atmospheric pressure.

It appears that the ferrous metal is transported into the network of the partially crystallized carbon and is distributed randomly in it. At least part of the dispersed metal is bound to carbon.

809885/0970 " ⁵ "

Some of the metal can move between the crystal planes of carbon.

The non-activated form of the carbonaceous material of the invention is produced by passing CO over a disproportionation initiator based on a ferrous metal. The carbonaceous material is formed on the surface of the dismutation initiator when this gas to a CO-containing is preferably exposed at 300 to 700 ⁰ C, 400 to 600 ° C. The pressure can be between about 1 and 100 atm, but 1 to 25 atm is preferred. The CO-containing gas preferably contains some hydrogen. Iron metal carbides are initially formed, but as this reaction proceeds, the carbonaceous material begins to collect on the surface of the disproportionation initiator. CO remains in contact with the disproportionation initiator ₍ until substantial amounts of non-activated carbonaceous material are deposited on it.

As a disproportionation initiator for CO on the basis of a ferrous metal, nickel, cobalt and / or iron can be used, their oxides, alloys or ores. This ferrous metal as a disproportionation initiator for CO is to be distinguished from the finely dispersed metal in or at least partially bound to the carbon, which is the lower Phase in the carbonaceous material according to the invention forms. In the catalytic carbonaceous one of the present invention Material is only of interest to the dispersed and bound metal.

Examples of iron metal initiators as they can be used are FepO ^ powder, hematite with mainly Fe ₂ O ^, electrolyte iron filings, KugeSn / von

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Carbon steel, steel wool, nickel oxide, cobalt oxide, high-purity nickel shavings, cobalt shavings, waste iron-nickel alloys, iron-cobalt alloys as well corrosion-resistant steel. Various iron ores can also be used as starting material, e.g. mesabi Range iron ore. The use of such ores is desirable because they are cheap and readily available. The ferrous metal but can also be on a carrier, such as silicate or alumina, provided that it does not has an adverse effect on the carbonaceous material. One advantage, however, is that you don't activated as well as for the activated carbonaceous material a carrier needs to increase the specific Surface, as the carbonaceous material itself already has a high specific surface. This lies

for example in the order of 50 to> 500 m / g,

ο normally between around 150 and 300 m / g.

In order for the carbonaceous material to have the desired reactivity, it should be formed in situ. Simply mixing the extraneous metal with carbon does not achieve the desired goal. In the case of the material according to the invention, the carbon is deposited in the form of fibers, possibly hollow fibers, on the surface of the heavy metal. The diameter of such fibers is on the order of about 0.02 to 2 µm and the length: diameter ratio (1 / d) is MO. When this fiber material was analyzed, it was found that it contained tiny particles of a metal (disperse phase) such as ^f * iron, iron carbide or iron-nickel alloys. Obviously, ferrous metal is transported into the carbon fibers. This ferrous metal is no longer in physical connection with the ferrous metal originally used, but is an essential component of the highly reactive carbonaceous material according to the invention. In methani-

809885/0970 " ⁷ "

ization with the aid of the carbonaceous material according to the invention can increase more than 95% of the free carbon Methane can be converted. This carbon-depleted material is then mixed with carbon powder and that Mixture exposed to hydrogen under such pressure and temperature, as they are normally used for methane. It can be seen that no methane is formed. It will pointed out that the distinction "or definition of the active ferrous metal in the carbon-containing according to the invention Material compared to the ferrous metal used as the starting product is difficult if maxi is used as the starting material a fine powder used. To identify the material according to the invention, test series were carried out, in which as an initiator for the CO disproportionation reaction plates made of iron, nickel, cobalt or a Iron-nickel alloy were applied onto which the carbonaceous material was then deposited. This forms a loose, wavy deposit on the plates, which can be easily removed from the plate. This carbonaceous material was then used as the basis for the investigations. Containing starting from an iron plate the carbonaceous material formed in situ has about 1 to 3.5% finely divided iron, as determined by spectral analysis and obtained gravimetrically after incineration. The remainder was essentially carbon with traces of hydrogen. Of the Carbon was partially graphitized (for partially graphitized carbon, see R. E. Franklin, "Acta Cryst", Vol. 4, p. 253 (1951)).

Fig. 2 shows a micrograph from a scanning electron microscope of carbon fibers formed on an iron plate at relatively low magnification and Fig. 1 a detailed view in a relatively large enlargement. The fiber material on which FIGS. 1 and 2 are based is involved it is a non-activated one, i.e. not with hydrogen

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treated material. In a fiber sample, iron was found in high concentration in area A. In area B, iron was also detected with the help of an electron probe. This iron inclusion is about 300 nm long and about 100 m wide (for the analysis method, see J. R. Ogren, "Electron Microprobe", chap. 6, "Systematic Materials Analyzes", Vol. 1, Academic Press, Inc., New York 1975). Assuming the fiber is solid and has a density between that of amorphous and fully graphitized Carbon, the dissolvability of the microprobe is around 1.5% by weight of Fe.

X-ray analysis of non-activated carbonaceous material deposited on an iron plate showed _; that the iron is present as iron carbide as well as' X iron. A "General Electric Model XRD-5" X-ray spectrometer was used for the Debye-Scherrer powder diagram. The same method of analysis showed that the X-ray detectable iron was present in the activated material only in the • ~ ^<-form.

As FIG. 1 shows, the iron or the iron compound is bound to the carbon. It has been tried, to loosen this bond and to loosen the iron compound or the iron from the carbon, namely by physical means Measures such as sifting or using a magnet. However, separation cannot be achieved in this way. Since the iron cannot be separated from the carbon by physical means, this means that at least part of the iron is intimately associated with the carbon and at least part of it is bound with carbon, possibly atomic or molecular. There is also the possibility that the iron is present as a solid solution in carbon. If so, the interfaces of the iron / carbon solid solution and crystals of the iron phase active sites that require the high reaction speed

809885/0970 - 9 -

favorable, represent. Whatever the type of bond between iron and carbon, it was found that iron, activated carbon, commercially available cementite Fe ₇ C or a physical mixture of iron and activated carbon do not have the properties of the material according to the invention. These form no methane into contact with hydrogen at elevated temperatures at a rate that even approaches de: ⁿ which he inventively achieved speed. This is shown in Table I.

C material
separate from
Fe initiator Table I. Methanation
speed
(Mole CH ^ / mole Ch) no C / Fe
Atom-
relationship 0.10 1. Yes 27.3 * 0.10 2. there 176 0.28 3. Yes 220 0.49 4th no 12.6 0.24 5. no 7 '* 0.20 6th 7 * --0.05
(CH ,, not fixed-
^f posed) 7th - 0.33 • ^ 0.0004 8th. - > 1000 <■ 0.0004 9. "- ^ 1000 <0.0004 10. 4.7 * ~ ₁₀ -7 11. ^ ■ 10,000

including starting irons

- 10 -

80 9 885/0970

The following raw materials were used in this table:

1. C deposited from CO + H ₂ , 550 ⁰ C, 1 atm, on highly pure iron sheet;

2. As 1, separated from the iron sheet and with hydrogen treated;

3. C deposited on 3.2 mm granules of carbon steel at 500 ⁰ C from C ¹ O + H _? , 1 atm;

4. Repeatedly repeated C deposition and hydrogen treatment at 55O ⁰ C, 7 to 17.5 kg / cm ² on 4.8 mm granules of carbon steel, separated from this and C deposited at 1 atm CO ι H ₂ ;

5. Mesabi iron ore, reduced with Hp, then C deposition from CO + H ₂ , 500 ° C, 1 atm;

6. As for 5, but 96 h in air before hydrogenation

7. Commercial cementite Fe ^ C;

8. Activated carbon Norit-A;

9. coke from coal gasification;

10. Activated carbon + electrolyte iron powder 1: 1;

11. Graphite powder, spectroscopically pure.

809885/0970

^ 283159Λ

9 now shows a scanning electron micrograph of a carbonaceous material according to the invention, obtained by CO disproportionation on a nickel alloy with about 50% Ni and 50% Fe. That from the alloy plate separate fibrous material contained 98.42% C, 0.58% Fe, 0.73% Ni and 0.94% H (uncorrected analysis data, so that the sum is not 100%). The area indicated in the photomicrograph was taken with an electron microprobe tested and contains iron and nickel in high concentrations in roughly equal parts. The X-ray analysis also revealed the presence of an iron-nickel alloy. It appears likely that thread C in Fig. 9 actually made of an iron-nickel alloy

,. ,Independently of, _ . _. r. .... ·, - ,. ·,. ^ j. stands / whether 9s thread C m Fig. 9 actually a solid solution of iron-nickel alloy, yet the investigation is clear that very small crystallites containing iron transported into the carbon fibers as well as nickel _(from the base plate have been and are in close connection with them or possibly even with the 'carbon are bound.

The ferrous metal dispersed throughout the carbon matrix is potentially a very effective catalyst. The ferrous metal catalyzes the reaction of C in the matrix with other reactants. As the reaction progresses If the material becomes depleted in C, it can, however, be enriched again with C by exposing it to a CO-containing gas. At an elevated temperature, the active component catalyzes the disproportionation of the CO.

It was found that even that at C largely depleted material in the reaction with hydrogen its specific reaction rate for methanation maintains. Surprisingly, almost all of the carbon can be removed from the carbonaceous material and the relatively high methanation rate is still

809885/0970 " ¹² "

Maintain dignity. This emerges from FIG. 3, where the specific methanation rate of the invention carbonaceous material is applied against the consumption of carbon by the hydrogenation. The den The values of the working conditions on which FIG. 3 is based were 1 atm and 570 to 600 ° C. at 110 cnr / min H- ,. The C-rich Material (i.e. about 96% C) initially had a reactivity of about 0.3 moles CH 2 / hr. Mol C, which gradually increased to about 0.63 (about 88% C consumed). When about 90% of the When the carbon was consumed or the material contained about 25 wt% iron, the reactivity dropped rapidly. When the C-rich material initially contained 95 wt% and 5 wt% Fe, the iron content after consumption was about 90% C about 35% by weight.

The material according to the invention retains its important Properties during many cycles of carbon depletion and carbon recharge. For iron as Ferrous metal was obtained even after 55 such cycles this hydrogen activated material at any time.

The material according to the invention retains its outstanding properties Properties even after a long storage time in a C-rich or C-poor state. However, when this material is exposed to oxygen, this can lead to oxidation of the ferrous metal, which has a negative impact on the catalytic activity affects, so that one should prevent the entry of air during storage. A ferrous material according to the invention showed no deterioration in methanation after a storage time of 24 h at room temperature.

The material according to the invention can with regard to its Composition can be varied over long distances, as can be seen from the following list:

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preferred

partially graphitized C 65 - 99.5% by weight 75 - 99% by weight dispersed ferrous metal 0.5 - 35% by weight 1-25% by weight

The percentages relate to a material after removal of the ferrous metal originally used. if the ferrous metal is iron, so should the non-activated Material preferably contains about 1 to about 3.5% Fe in addition to about 96.5% C.

It has been found that sometimes the carbonaceous material of the present invention when treated with hydrogen showed an improvement in the rate of carbon deposition and methanation. If the ferrous metal is iron is, the rate of deposition of C is

> 10 g / hg Fe and the rate of methanation

> 0.3 mol / h.Mol C. The C deposition was carried out at 1 atm and .500 ⁰ C in a CO stream of 10 mol / hg Fe with a gas

a mixture of 80 vol .-% CO and 20 vol .-% H ₅ determined, the methani-

o '

Conversion rate at 550 C, 1 atm and a minimum H ₂ flow of 2 mol / h MoIC.

Although the CO for the deposition of the invention Materials Hp can add, you won't get through for so long Hydrogen activated material takes place as a deposit on the originally applied ferrous metal. Will the C-containing material, which is initially formed, is subjected to hydrogenation in the course of methane production, then the activation of the material according to the invention takes place. The formation of this material was found when about 15% by weight of the originally deposited C was removed by hydrogenation. The hydrogen should in general contain no more than about 1% by volume of water.

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If one removes the activated material from the originally used ferrous metal, one finds that it has the same appearance as the deposited material,

that Fe
however, the X-ray diagram shows that it is present as o ^ iron and not as carbide. The activated material still has a greater reactivity after several cycles of carbon deposition and methanation than before these treatments. With these alternate treatments, the composition can change as follows:

Weight %

partially graphitized C 65-99.5

Ferrous metal 0.5 - 35

H ₂ 0.1-3.0

Hydrogen is strongly associated in the material according to the invention. If the iron-containing material is ^{heated in a stream of nitrogen from about 200 to about 95O 0} C and the escaping carrier gas is analyzed, the desorbed gases are mainly Hq and CO, the amount of H2 in the material according to the invention being more than 50,000 times Is the amount that rj -iron can solve. More than two thirds of the IL escapes at temperatures above 700 C.

When iron oxides, such as iron ores, are initially used as disproportionation initiators, they are first reduced with CO + Up and only then does the carbonaceous material begin to form on the iron. The time in which the iron is in contact with CO-containing gas is therefore of importance. In the case of Fe ₇ O ^ and CO-containing gas at 1 atm and 600 C, the iron oxide is at least partially reduced to iron. This is shown by weight loss due to the splitting off of oxygen. If the iron oxide is in contact with pure CO for 15 minutes, a weight loss of about 22 ½ is established

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solid (oxygen makes up about 27.6% by weight of the iron catalyst). Some carbon is deposited on the iron in the form of Fe- ^ C. After 30 minutes the weight loss was 15% and the carbon deposition took place in the form of the carbide, primarily Fe ^ C. After 60 minutes of contact of the iron oxide with CO, a slight weight loss of about 10% was still observed and essentially all of the carbon deposited on the iron oxide was found as carbide, mainly as Fe ^ C. After 4 hours there is a weight increase of about 75% due to the deposition of partially graphitized carbon. The above samples
after 1.5, 30 and 60 min did not show a suitable methanation rate, whereas the sample after 4 h at H ₂ , 1 atm and 55O ⁰ C, a methanation rate of
yielded at least 0.1 mole / hr-mole C at an Hp flow rate of 2 mole / hr-mole C.

"[Vi Ώ * l · * Q" V "» Π £ 3 ~ j

The carbonaceous according to the invention can be
due to its particular effectiveness in methane formation
also apply'for the production of a strong gas, i.e. one
Gases'high calorific value) from coal or another fuel. It is particularly advantageous that methane can be formed without the need to use pure oxygen or to remove nitrogen, carbon dioxide or other inert gases from the starting gas. CO and Hp can be obtained from the starting gas with the formation of the carbonaceous material according to the invention on the ferrous metal. Then it becomes a gas containing Hp
brought together with the material according to the invention under such working conditions (temperature, pressure, throughput) that
a gas with at least 20% by volume methane is formed. By
the high reactivity of the material according to the invention with Hp makes this reaction extremely fast. For the production of a gas having at least 75 vol .-% CHr are therefore very low contact times, eg 1 to 50 s, it is necessary, preferably 5 to 30 s. For the Methaninierung one needs at least 35O ⁰ C, preferably about 400 to 700oC. The pressure

809885/0970 " ^1β "

can be between atmospheric pressure and about 100 atmospheres, preferably "to 25 atmospheres".

For the production of a methane-rich strong gas one can use any CO-containing starting gas, for example from the gasification of coal with air or air + steam, whereby a generator gas with a calorific value or a thermal energy of 243.25 "to 521.25 kJ can be used / nr ⁵ (70 to 150 BTU / cb.ft). In the in situ gasification of coal, for example, it is possible to obtain a gas with a calorific value of 347.5 kJ / nr (100 BTU / cb.ft). The generator gas contains CO, H ₂ ^ Np and COp. The coal is preferably gasified with an air / steam gas mixture in order to obtain a generator gas with a high proportion of CO and Hp. Normally, a generator gas (dry) contains about 15 to 30% CO, about 5 to 30% H ₂ , about 40 to 60% N ₂ and about 2 to 10% CO ₂ . All such CO-containing gases can be used with the catalyst according to the invention to form a methane-rich gas similar to natural gas with a calorific value of 1737.5 to 3475 kJ (500 1000 BTU / cb.ft).

In general, such a generator gas also contains water vapor and small amounts of other gases such as methane, H ₂ S, COS and the like. For operation at atmospheric pressure, the water content should therefore be reduced to below about 6% by volume and the sulfur content to below about 10 ppm. If the CO-containing starting gas contains Hp, the molar ratio CO: H _{2 should be} > ~ 1: 2, preferably i-1: 1. The preferred molar ratio is between about 1: 1 and 100: 1. If the starting _{gas contains CO 2} , the molar ratio CO: COp should be high, ie at least 1: 1, preferably 2: 1 to 3: 1 and above. The C deposition takes place with sufficient speed at a CO ₂ : CO ratio of 3.

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The CO-containing starting gas should, if possible, no contain larger amounts of sulfur, i.e. no more than about 20, preferably no more than about 10 ppm S, calculated as HpS. If necessary, the sulfur content can be reduced by conventional methods, e.g. with a. Amine or by mixing the starting gas with an aqueous Solution of an alkali or alkaline earth carbonate washes, e.g. with a hot potassium carbonate solution. Apart from these known methods for the separation of HpS from the starting gases this can also be done on the material according to the invention or a mixture of the material according to the invention with the Remove the ferrous metal originally used. In this case the ferrous metal reacts with the sulfur to form of sulfides within the material. This reaction deactivates the carbonaceous material. In such a In this case, however, the sulfur-laden material according to the invention is no longer suitable for methane production.

With the materials according to the invention, gases with relatively high nitrogen contents, ie of at least 70% by volume, can be used. It is therefore not necessary to produce the CO-containing gas in an Np-free oxygen atmosphere. In other words, air can be used to gasify the coal and not pure oxygen is required. This increases the profitability a lot. Another economic aspect is that the combustible part of the starting gas, i.e. mainly CO, can be separated from the permanent gases or the non-combustible part with little effort with the help of the formation of the carbon-containing material ^{E FiIin Ld} Her ^: / You then only need to bring this into contact with Hp in order to obtain a methane-rich gas. This carbon-containing material does not need to be reacted directly with Hp, because it retains its reactivity

-18-809885 / 097 0

a relatively long time. For example, a sample was reacted with H ₉ after 5 days and it was found that the CH ^ formation took place at the same rate as freshly produced material.

The carbonaceous material according to the invention can also be used with a diluted or used generator gas or work its exhaust gas. For example, coal can be converted into generator gas with air under controlled conditions, bring this to reaction with iron oxides, whereby primarily iron, but also iron carbides and iron oxides are formed with a low oxygen content and a partially used generator gas is discharged. This contains now about half of the originally contained CO and fl ·? and is used with the disproportionation initiator according to the Invention brought into contact, whereby the carbonaceous material of the invention is obtained. H “is obtained by treating the reduced iron oxides with steam and this can now be applied to the material according to the invention Convert methane.

According to one embodiment of the invention, the C-containing material is usually mixed with the originally used ferrous metal back and forth between two reaction zones, the material coming into contact with the partially consumed generator gas in one and the hydrogen-rich gas in the other with the formation of methane. In other words, the material alternates between a high carbon and a low carbon state. The material used for methanation is rich in carbon. During methane formation, part of the carbon (at least 15 % by weight) is consumed, so that a C-poor material can be transferred to the other zone, where it is converted back to a C-rich material with the help of the generator gas. The low-C material, ie the one with

- 19 809885/0970

Hydrogen activated material ₍ in the first cycle contains about 5 to 35% by weight of dispersed ferrous metal, about 95 Ms of 65% by weight of C and about 0.1 to 3% by weight of H _2. A modification of this procedure is to that the material remains in place and the gas flows supplied to this zone change, namely one generator gas and one hydrogen-rich gas.

A particular advantage is that the C-containing material carried along by the gas streams is in the magnetic field can be deposited, since the ferrous metal is and remains ferromagnetic within the C-containing material.

Another advantage is the possibility of generating energy from the partially consumed generator gas or other gases that can serve as a source of CO. After the formation of the C-containing material according to the invention and the Hydrogen production by the steam iron process is the generator gas burned off with air to oxidize the remaining combustibles, and the remaining gas is then expanded in a gas turbine to generate electricity.

A particularly advantageous application of the invention is shown in FIG. The starting point is a desulphurized generator gas 100 which, for example, contains 50% N ₂ , 25% CO, 18% H ₂ , 6% CO ₂ and 1% CH ^ (dry). The sulfur content must be below about 20 ppm.

This generator gas reaches the fluidized bed reactor 102 via 101 for carbon deposition on low-carbon material, the ferrous metal of which is iron. In this, the CO of the generator gas is disproportionated at around 650 ° C. and a pressure of 10.5 to 17.5 kg / cm ² .

- 20 809885/0970

The material according to the invention thus formed is over

103 led to methanation 104, which ^{takes place at 525 to 700 °} C., in that C of the material according to the invention _{reacts with H 2} , which is fed in via 106. Since methanation is strongly exothermic and lower temperatures favor higher methane concentrations, methanation is expediently carried out in stages, with solids and gases being cooled between the stages. Depending on your requirements, one or more coolers can be required for this. According to this flow diagram, methanation 104 is carried out with the aid of a cooling coil, into which water enters at 107 and steam exits at 108. The CH // Hp gas mixture comes out

104 via 109 in the cooler 110 and can at 111 for further Recovery to be drained.

The partially consumed generator gas from 102 is fed via 112 into a heat exchanger 113, in which it is brought from 670 to 920 ^° C., for example. The remaining CH ^ is converted to H ₂ O, CO and CO ₂ . The partially consumed generator gas with a low ratio of CO: CO ₂ , containing mainly W ₂ , CO, H ₂ , H ₂ O and CO ₂ , emerges from 113 at 114 and leads to the reduction of the iron oxides 115 | for the lower C0 / C0 ₂ ratio is still sufficient. Of Fe ₂ O ^ obtained FeO, from CO CO ₂ and of H ₂ H ₂ O. The reduced iron oxides are routed via 116 in the hydrogen generator 117, which is supplied with 118 D _a mpf and in the FeO to Fe ₂ O ^ and H ₂ reacts. Fe ₂ O ^ goes back via 119 in 115, H ₂ and steam are fed via 120 to the heat exchangers 121 and 123 to the condenser 122, in which the steam content of the hydrogen is reduced to about 1%. This dry hydrogen is now passed through 124 and into the methanation 104.

The used generator gas from 115 is fed to the furnace 126 via 125 to recover the remaining energy content, the compressed air via 127 and the compressor 128 (10 to

809885/0970 -21-

17.5 atü); the thermal energy generated in furnace 126 is partly consumed by the heat exchanger 113, in which the heating of the generator gas takes place. the Residual heat is made usable by the furnace gases leaving the heat exchanger 113 via 129 of a turbine 130 supplied and relaxed there with the formation of electric current 131. The exhaust gas is cooled at 133 and at 134- blown to the atmosphere.

This method has several major advantages. 1. A very high proportion of the energy content of the generator gas is used to produce valuable products, methane and electricity; 2. No need for expensive oxygen; 3. The heat energy released during methanation and the sensible heat from the exhausted generator help high temperatures for a very efficient power generation available, so that the losses are very low.

Another variant of the method is shown in FIG. Desulfurized generator gas from 1 (50% N ₂ , 25% CO, 18% H ₂ , 6% CO ₂ , 1% CH ^ (dry)) serves as the starting gas and comes, for example, from a conventional gasification of coal with steam and air, a in situ gasification of coal or the like. The desulphurisation is carried out down to below about 10 ppm HpS.

The desulphurized generator gas and, for example, iron oxides such as a mixture of Fe ₂ O- *, Fe ^ OA and FeO ₍ are in a fluidized bed reactor or an eddy current reactor with pneumatic conveying 2 at 550 to 850 ⁰ C and 1 to 100, preferably 1 to 20 atm, The temperature and pressure depend on the heat balance and the desired methane concentration.The contact time must be sufficient for a partial reduction of the iron oxides to FeO, Fe and Fe ^ C with the help of H ₂ and CO des

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To enable generator gas. Some of the H ₂ and CO are consumed, which is especially good for Hp.

The partially used generator gas takes the reduced iron compounds with it and gets into a Cyclone or a similar dust separator 3. The solids discharged from it reach one below via 4 second pneumatic conveyor reactor 5, where it is supplied with steam from 6 at a temperature of 500 to 000 C under a Pressure of 1 to 100 atm. Obtained by the reaction of the steam with the reduced iron solids a hydrogen-rich gas, which in addition to Hp and Steam still contains some CHa CO and COp.

This hydrogen-rich gas with entrained, re-oxidized iron particles leaves the reactor 5 via 7 and again enters a cyclone or the like 8. The solids separated therein are returned via 9 into the first reactor 2, whereby the solids cycle between the reactors 2 and 5 is closed.

After the solids have been separated off, the partially consumed generator gas, which still contains, for example, 15% CO, 6% Hp, 16% CO ₂ . 1% CH _Zf and 62% N _? (dry), cooled in the heat exchanger 10 with simultaneous steam generation and arrives via 11 at the bottom of the pneumatic conveying reactor 12 for C deposition on the entrained C-poor solids. The contact time can be different, the temperature is 300 to 600 ° C and the pressure 1 to 100 atm. The material now enriched with C due to the disproportionation of CO is obtained from the CO content of the partially used generator _{gas, by converting CO and H 2} or by reducing CO with the help of other available reducing agents.

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The C-rich solids are entrained with the gas to the cyclone or the like 13 and then reach the bottom of the reactor 14 for methanation, in which they have been entrained by hydrogen-rich gas from the reactor 5 after passing through the heat exchanger 8a and the cooler ob. They then react with Hp in the first stage 15 to form methane, primarily through direct reaction of C and Ho. This reaction is exothermic, so that cooling must be carried out between the stages if higher methane concentrations are desirable. In the embodiment shown here, this is done with the aid of the cooler 16, which is then followed by the second methanation stage 17. Depending on the desired ratio CH ^: H ₂ , the working pressure in the methanation varies up to 100 atm and is preferably not more than 20 atm. Depending on the desired product, one or more intermediate cooling'- ·: ..- ',, will be provided. The working temperature in the first stage methanation can be from 700 to 75O ⁰ C, but in the later stages of the methanation a lower temperature must be maintained to a high ratio CH ^: to come H _2.

The mixture of gas and low-carbon solids leaving the methanation is first separated in cyclone 18 and the low-carbon solids are returned to reactor 12 via 19. The raw gas still contains some dust, which is removed in the separator 20 - possibly a magnetic separator, since the dust is essentially ferromagnetic. But you can also use sand filters, bag filters or the like. The gas freed from suspended matter is cooled in the heat exchanger 21 and at the same time steam is generated, then passes for further cooling and drying in the cooler 22, from where ^a purified gas is available for use.

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The hot, used generator gas leaves the cyclone 13 and enters the dust separator 23 for the suspended matter proportion that was not retained in cyclone 13 is. Here, too, it can be a magnetic separator, since the solids are generally ferromagnetic. It sand filters or bag filters can also be used. The hot, particulate-free, used generator gas still contains always some Hn and CO and is burned off with excess air, so that you get an exhaust gas containing Np, COp and HpO. This hot exhaust gas is expanded in the gas turbine 24 in order to generate the energy and / or energy required for the system in this way to generate electricity. Further process steam can be generated by cooling the exhaust gas.

This process variant has two major advantages, namely the separation of unwanted Wp and COp from the Methane and hydrogen containing gas occurs through a relatively simple separation of solids and gases and not through a complicated separation of Np and Op. like this was customary up to now and the generator gas is used to a greater extent than it is with the usual steam-iron processes was the case, because the generator gas is first used partially for the reduction of iron oxides (steam-iron process) and then completely causes the deposition of the carbon for the reaction.

Another possibility is shown in FIG. 5; here generator gas is first generated with the help of compressor 1 compressed to 3 to 4 atmospheres and then for C deposition with the help of ferrous metal oxide, e.g. iron oxide ^ in the reactor

2 headed. The iron oxides located there are reduced and at the same time C-containing material is deposited on the reduced oxides. The reactor 2 is at a temperature of about 350 to 50O ⁰ C at a working pressure of about

3 to 4 atmospheres. About 70% of the CO and H ₂ -

809885/0970

as

The content of the generator gas is consumed with the formation of iron compounds with the iron oxides and C-containing material is deposited according to the invention. The used generator gas with a temperature of approximately 350 to 500 ^° C. is mixed with air and burned off in the combustion zone 3. This exhaust gas can either be fed directly into the compressor or into a turbine for generating electricity by expansion without the need for a steam boiler for the waste heat. Entrained dust is expediently removed in a magnetic separator.

The C-containing material, including the iron originally used, is pneumatically conveyed into a fluidized bed reactor 5 for methanation with Hp at a temperature of about 480 to 535 ° C and a working pressure of about 3 to 4 atmospheres with formation of a methane-rich gas. This is cooled in the waste heat boiler 6 with the generation of steam) the low-carbon material from the methanation 3 is pneumatically conveyed to a fluidized bed reactor 4 for hydrogen generation with the aid of steam at 535 to 650 ^° C. under a pressure of 3 to 4 atü supplied. Vapor-containing hydrogen is obtained. The re-formed iron oxides are returned to the reactor 2, the moist hydrogen is cooled in the cooler 7, the condensate is discharged and the dry hydrogen is sent to the methanation 5.

Sulfur compounds such as HpS, COS, CSp or SOp can from the generator gas with the aid of that formed in reactor 2 Material according to the invention are deposited. It exists but also the possibility of some of the C-containing hydrogenated To use material from the methanation 5 directly to remove the sulfur compounds of the generator gas.

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809885/0970

Another possibility of using the material according to the invention is shown in FIG. In this embodiment the solids remain in the individual reactors either in the form of a fixed bed or a fluidized bed and the gas flows are switched periodically, namely the reactors are supplied with generator gas once and steam once Reactors can operate in one of two ways; the

is
the first indicated in FIG. 6 by the solid line, the second by the broken lines. In the first type, generator gas is passed into the reduction reactor 6, in which it encounters iron oxides. The partially consumed generator gas then passes through a boiler into the reactor 2, in which the C-containing material according to the invention is formed from an iron-containing starting material. At the same time, steam is introduced into the hydrogen generator 4, which forms hydrogen by reducing it to iron. Hydrogen goes into the reactor 3 for methanation with the aid of the material according to the invention, which has previously been formed therein in order to now form methane. The gas feeds to reactors 2, 3, 4 and 6 are switched over according to a predetermined program. According to the broken lines, hydrogen is now formed in reactor 6 and passed into reactor 2, where methane formation takes place on the C-containing material. The exhausted generator gas passes from the reactor 4 into the reactor 3, where it forms the C-containing material again.

In the variant of the method according to FIG. 5, a partial used generator gas for the production of a methane-rich gas in a single reactor. the Reaction cylinders have porous walls that allow gas to pass through, but the porosity is so low that that the materials according to the invention and the starting material used for its preparation are retained. Here one prefers as starting material and disproportionate

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The initiator is an iron granulate.

The iron granulate "is initially in the funnel 1, from which the granulate under the action of the Gravity via 2 and 3 in the porous-walled reactor for carbon deposition 4 with an interior space 5 got. In the interior 5 partially consumed generator gas is fed at the top at 6. This gets through the inner porous walls into the reactor 4 and is in contact with the catalyst for a sufficient period of time Pressure and temperature, so that the C-containing material according to the invention is formed from the granules. That completely spent generator gas then leaves the reactor 4 via the porous outer wall 8.

The granulate with the C-containing material sinks from the reactor 4 Material via 9 into the methanation reactor 10, which is delimited by a porous outer wall 11 and a porous one Inner wall 12 and coaxially surrounded by an impermeable

Wall 13 with the formation of an annular space 14. Hydrogen is introduced into the interior 15 via 16, penetrates the porous inner wall 12 and is converted into a methane-rich gas in the reactor 10 on the C-containing material. This leaves the R _e actuator 10 via the porous outer wall 11, collects in the annular space 14, is passed therefrom via 16 and 17 in the central space 18 within a second methanization reactor 19th Here, too, there is again a porous inner wall 20 between 18 and 19.

The C-poor material from the reactor TO leaves this above 21, is cooled in 22 with water, which is supplied via 23 and from which steam is released at 24. the Cooled solids fall into the second methanation reactor 19, from which a low-carbon, iron-containing material over

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the delivery line 27 reaches task 1 again. Methane-rich gas leaves the second reactor 19 via the outer one porous wall 24 and the gas discharge line 26.

The invention is further illustrated by the following examples.

example 1

On a mild steel granulate with a size of 2.3 mm in an amount of 5 g carbon was deposited by decomposition of CO at 55O ⁰ C from a gas mixture CO + H ₉ in

from ~ z a tube furnace; Flow rate CO: 100 cm / min, of H ₂ : 20 cnr / min. After about 4 hours, 2.7 g of C-containing material with a content of 3.7% by weight Fe were removed from the granulate and 0.27 g of this C-containing material were exposed to the same gas mixture at 500 ° C. and 1 atm. The C deposition rate was 8.8 g C / hg dispersed iron.

This C-containing material produced a methanation rate of 0.52 mol CH ^ / h. mol C.

Carbon was again deposited on this hydrogenated material in the same gas mixture under the above conditions. The C deposition rate was 39.4 g C / h.g dispersed iron.

This alternating treatment for disproportionation of CO with C deposition and hydrogenation to consume the carbon was repeated a few times and the results are summarized in Table II.

809885/0970

& - 2831534

! ft

Table II

g C / h.g Fe mol CH ^ / h.Mol C

1.C deposition 8.8

1st methanation 0.52

2.C deposition 39.4 '.. _'

2nd methanation 0.53

3. C deposition 47.8

3. Methanation 1.12

4.C deposition 41.5

4th methanation 1.33

The hydrogen activated material had a C deposition rate> 10 g C / h.g dispersed Iron. After a few cycles of carbon capture and methanation, the rate of methanation rose to over 1

Example 2

600 g of mesabi iron ore (hematitic, containing 55.3% Fe, 8.1% Si, 0.8% Al), 0.10 to 0.25 mm, 1.91 g / cm ³ , were placed in a vertical tubular autoclave Made of corrosion-resistant steel, clear width 830 mm, height approx. 2.4 m, introduced and reduced with hydrogen at a throughput of 2300 nr / m .h. The reduced ore was subjected to a series of alternating treatments for carbon deposition and methanation, the carbon deposition taking place with a gas mixture containing Np, CO and Hp of different compositions and the methanation with pure Hp. The gas volumes fed in and the reaction gases brought to normal conditions became wet with the aid of a flow meter

809885/0970 - 30 -

- 3Θ--

measured. The gas composition was determined by gas chromatography.

Output gas
N ₂ H ₂ 1 r Table III W.
CO Stay-
⁰ C ata ^time s 1, 9 CH ₄ min thereafter
C: Fe 46.6 8, 9 C deposition 45.3 456 6.1 1, 7th 53 65 1.29 42.5 6, 9 50.6 440 3.4 1, 6th 63 75 0.88 A. 44.2 6, 4th 48.9 435 3.5 1, 8th 62 90 0.80 B. 44.2 7, 48.4 416 4.7 70 110 1.12 C. Me thani she tion D. ⁰ C ata s min max. % thereafter
C: Fe 540-673 6.8 4.9 174 , 5 0.08 500-700 11.6 9.1 120 , 0 0.04 A. 500-672 11.6 11.0 140 , 0 0.01 B. 500-635 13.6 15.0 165 , o ¹ 0.15 C. D.

The methanation is strongly exothermic and the temperature was only set in this experiment by setting the WasiErstoff throughput regulated.

Example 3

2.88 g of a 1: 1-nickel-iron alloy were 10 minutes at 982 ° C in a muffle furnace and then oxidized at 500 ⁰ C a gas mixture of 85 parts by volume CO and 15 vol 9o - _9% H at a. Throughput of 200 cm / min exposed to 9.33 h; afterward

809885/0970

- 31 -

the C-containing material was removed from the alloy and found, based on elemental analysis, to contain 98.06% C, 0.54% Fe, 0.53% Ni and 0.16% H ₂ .

This C-containing material was subjected to the alternating treatment methanation and C deposition three times. The conditions and results are summarized in Table IV. The rates of carbon capture and methanation increase, as the table shows, as the operating temperature increases.

Table IV

g C / h. g Fe mol CH ₄ / h. Mole C

1. Methanation 0.10

1. C deposition 35.2

2. Methanation 0.12

2. C deposition 38.8

3. methanation 0.20 3. carbon deposition 45.3

Example 4

Samples of C-containing material containing free carbon were prepared by disproportionation of CO on plates or granules of iron, nickel, cobalt and a 1: 1 nickel-iron alloy, the fibrous material removed from the base metal and at 550 ⁰ C and 1 ata exposed to a stream of dry H ₂ at a rate of about 2 mol H ₂ / h. Mol C. Table V shows the methane formation rates for the various starting metals.

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Table V

Moles CH ^ / h. Moles C.

Iron 0.10

Nickel 0.19

Cobalt 0.34

Iron-wrap alloy 0.10

Example 5

10 g of carbon steel granules, 3.175 mm in diameter, were placed in an alumina boat which was held in the center of a ceramic reaction tube. On the granules was carried out at 510 ⁰ C and atmospheric pressure for 5 h, a gas mixture of 100 CRRR / min CO and 20 cm / min EU slides. A total of 1.94 g of carbon was deposited. The carbon-containing material was carefully freed from the steel balls. It contained 2.08% Fe; 0.992 g of this material were placed in an aluminum boat and this was placed back in the reactor and the above gas mixture was again passed through for 2 hours at 408 ° C., 0.2 g of C was also deposited, as can be seen by determining the COp concentration of the escaping gas could be determined.

110 cm ^J / min of pure hydrogen were then passed over the sample at 56O ° C and the methanation continued with the addition of hydrogen until about 0.2 g C <could be determined from the methane concentration and the flow rate of the exhaust gas and had been gasified. The mean methanation rate was 0.2 mol / h. Mol C.

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It has now been on the sample 40 cm / min pure Np passed and the sample heated slowly to 865 ° C, held at this temperature for about 1 h and then cooled under a nitrogen stream to 560 ⁰ C.

At this temperature it became 110 cm * ^ purer again Hydrogen for methanation passed through until again 0.2 g of C were gassed. The mean methanation rate was now 0.26 mol CH ^ / h.g atom C.

_o held

It was again to 865 C under nitrogen / and then

Methanized at 560 ° C. In this case it was the middle one Mettling speed remained unchanged.

It follows that a brief heating of the invention Material at high temperature does not affect its reactivity to hydrogen. Also will the catalytic activity with regard to the conversion of CO and Hp to methane is not reduced.

According to the same heat treatment, the remaining carbon-containing material at 450 ⁰ C was added a stream of 110 cm ^ EU / min and 30 cmr C0 / min exposed. The emerging gas gave an average methane formation rate of 0.24 mol / h.Mol catalyst.

809885/0970

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R e r s e

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Claims (16)

Claims 1 . Carbon-containing, catalytically active material, containing at least 0.5 % by weight of a metal of the iron group or its compound, dispersed within the carbon, closely associated with it or at least partially bound to it. 2. Carbon-containing material according to claim 1, in which the metal of the iron group iron, nickel, cobalt, their Alloys and / or carbides. 3- carbon-containing material according to claim 1 or 2, that it also contains hydrogen. 4. Carbon-containing material according to claim 2, characterized in that the metal of the iron group Λ -iron is .. 5. carbon-containing material according to claim 3 or 4, characterized in that the hydrogen content is 0.1 to 3 wt .-%. 809885/0970 INSPECTED 6. A carbonaceous material according to claim 1 to 5, characterized in that it 65 to 99.5 wt -.% C, 0.5 to 35 parts by weight 96 ¹ ^ Fe and 0.1 to 3 wt .- ^ H ₂ contains. 7. carbon-containing material according to claim 6, characterized in that. that it is 96.5 to 99% by weight C and 1 to 3.5 wt .-? U metal of the iron group contains. egg. Carbon-containing material according to claims 1 to 7, characterized in that it contains 65 to 99% by weight of partially graphitized carbon and 1 to 35% by weight % By weight of CX iron and optionally hydrogen. 9. A method for producing the carbon-containing material according to claim 1 to V>, characterized in that a CO-containing gas is brought into contact with a disproportionation initiator based on a metal of the iron group for the deposition of carbon on the initiator metal and optionally the obtained carbonaceous material activated with hydrogen " 10. The method according to claim 9, characterized in that g e k e η η that the initiator iron, cobalt, nickel, their oxides, their alloys, their ores and / or Mixtures used. 11. The method according to claim 9 or 10, characterized in that the carbon deposition at 300 to 800 ⁰ C, preferably at 350 to 700 ° C, is carried out. 12. The method according to claim 9 to 11, characterized in g e that the carbon deposition is carried out under a pressure of 1 to 100 ata. - 3 809885/0970 ~ ³ ~ 283 Ί 13. The method according to claim 9 to 12, characterized in that the on the initiator formed carbonaceous material decreases from the initiator, optionally before or after the activation with Hydrogen. 14. Use of the material according to claim 1 to 8 for the production of a particularly methane-rich strong gas by passing hydrogen over it, consuming part of the carbon. 15. Combined process for the production of the material treatment according to claim 1 to 8 and production of a methane-rich gas starting from a generator gas, thereby g e k e η η - ζ ei chnet that one
on (a) the disproportionation initiator based on a Metal of the iron group separates carbon which contains at least 0.5% by weight of the metal of the iron group, and (b) this carbonaceous material at elevated temperature with hydrogen, consuming part of the Carbon and formation of methane and the process stages (a) and (b) repeated alternately. 16. The method according to claim 15, characterized geke η η et draws that the process stage (a) at 500 ⁰ C with a gas mixture of 80 Vo 1.-96 CO and 20 vol .-% Hp ^{un (} i the process stage ( b) at 55O ⁰ C carried out. 809885/097 0