EP3762350A1

EP3762350A1 - Manganese-doped nickel methanization catalysts having elevated sulphur resistance

Info

Publication number: EP3762350A1
Application number: EP19711029.9A
Authority: EP
Inventors: Andreas Geisbauer
Original assignee: Clariant International Ltd
Current assignee: Clariant International Ltd
Priority date: 2018-03-09
Filing date: 2019-03-06
Publication date: 2021-01-13
Also published as: JP2021516612A; JP7152495B2; WO2019170779A1; CN111819163A; US11261137B2; US20210047246A1

Abstract

The invention relates to a method for the methanization of carbon monoxide and/or carbon dioxide in a reactant stream containing carbon monoxide and/or carbon dioxide, hydrogen and more than 1 ppb sulphur, using a catalyst containing aluminium oxide, an Ni active mass and manganese, characterized in that the molar Ni/Mn ratio in the catalyst lies in the range between 1.0 and 15.0, preferably between 2.0 and 12.0. The invention further relates to a method for the methanization of carbon monoxide and/or carbon dioxide in a reactant stream containing carbon monoxide and/or carbon dioxide, hydrogen and more than 1 ppb sulphur, wherein the reactant stream is passed through a reactor with a catalyst and the catalyst contains an Ni active mass and manganese, with a molar Ni/Mn ratio in the catalyst in the range between 1.0 and 15.0, preferably between 2.0 and 12.0, characterized in that the catalyst absorbs the sulphur contained in the reactant stream and simultaneously catalyses the methanization reaction.

Description

Manganese doped nickel methanation catalysts with increased sulfur resistance

The energy supply through the so-called renewable energy photovoltaic and wind energy suffers from the problem of weather and daytime dependent fluctuations in electricity production. To ensure security of supply, a way has to be found to intercept weather and time-dependent fluctuations in electricity production. One potential method of chemically storing energy is the power-to-gas process, which uses excess electricity to split water into hydrogen and oxygen by electrolysis. What hydrogen, in which the energy is stored after the electrolysis of water, can be stored even with great effort or transported to the consumer. In a further step, using the power-to-gas process, the hydrogen is converted into methane and water in the methanation reaction with carbon dioxide, which acts as a climate-damaging greenhouse gas in the atmosphere. Methane can be easily stored in existing infrastructures, which have capacities for storage in the range of several months, can be transported almost lossless over longer distances and can be reconverted in times of energy demand. The methanation reaction, which involves high energy release and is usually catalyzed, is at the heart of the process. The high exothermicity of the reaction (-165 kJ / mol) gives rise to two direct problems. On the one hand, at high temperatures the ther modynamic equilibrium limits the maximum achievable yield of methane. For the feeding of methane into the natural gas network, a purity of 95% is necessary in Germany. This results in the demand for a high catalyst activity, so that at industrially applied reaction pressures at low temperatures higher yields of methane can be achieved.

In order to ensure a constant product gas quality in the hydrogenation of CO ₂ and CO to methane on nickel-based catalysts, it is necessary to maintain as high a catalyst as possible in terms of activity and selectivity. However, activity and selectivity of a catalyst in industrial use decrease over time due to various deactivation mechanisms.

In addition to thermal and mechanical deactivation processes, above all chemical processes, due to sulfur in the gas stream, play an important role. As is known from practice and the literature, already very small amounts of hydrogen sulfide in the order of <100 ppb lead to poisoning of nickel catalysts, accompanied by losses of activity. In this case, H ₂ S reacts with nickel, so that a poisoning front of nickel sulfide migrates through the catalyst bed. The nickel sulfide formation can be described by at least two Ni _x S _y phases: Ni ₃ S ₂ (Heazlewoodite) and Ni ₃ S ₄ (Polydymite).

Depending on the origin of the used C0 ₂ or CO, this contains corresponding amounts of impurities. For the purification of C0 ₂ from biogas plants, which contains H ₂ S in the order of 200 to 1000 ppm, this is presently consuming adsorptively pre-cleaned to reduce primarily sulfur impurities such as H ₂ S to a mini mum.

The methanation reaction is also of key importance in large-scale SNG (synthetic natural gas) plants based on coal gasification. The hydrogen which is recovered by the coal gasification and the subsequent shift reaction (C0 + H ₂ O-> -C0 ₂ + H ₂ ) is purified, for example by wet scrubbing with cold methanol, and contains low sulfur loads of the order of <100 ppb , However, even these low sulfur levels can adversely affect the life of subsequent synthesis reactors.

Catalysts with an increased sulfur resistance could reduce the pre-cleaning effort or increase the service life of the synthesis reactor, with a positive effect on the profitability of the overall system.

US 4132672 A discloses an improved process for the conversion of hydrogen and carbon monoxide to a methane-enriched gas using a supported nickel catalyst obtained by the addition of a small percentage of iridium metal, typically 0.1 to 1, 0 wt .-% is promoted. This promoted catalyst is very active in methanation and has good resistance to sulfur compound poisoning.

Considering the reaction equilibrium, since the methanation of CO and C0 _{2 is} highly exothermic, catalysts with increased resistance to sulfur at low temperatures are desirable, but this is very challenging due to the exotherm of NiS formation. At higher temperatures (> 600 ° C) is the Binding of sulfur to nickel catalysts reversible, the position of the reaction equilibrium to high levels of methane in the product gas but unfavorable.

It is an object of the invention to provide a process for the effective methanation of carbon monoxide and / or carbon dioxide, with high selectivity and activity and improved stability in sulfur-containing educt streams.

This object is achieved by a method for the methanation of carbon monoxide and / or the carbon dioxide, in a reactant stream containing carbon monoxide and / or carbon dioxide, hydrogen and more than 1 ppb sulfur, using a catalyst, the alumina, a Ni Active composition and Mn, characterized in that the molar Ni / Mn ratio in the catalyst in the range between 1, 0 and 15.0, preferably between 2.0 and 12.0, particularly preferably between 3.0 and 10.0 , or more preferably in the range between 3.5 and 5.5 or 7.5 and 9.5.

Surprisingly, it has been found that a Mn-containing Ni catalyst has a high sulfur resistance and a high sulfur capacity. The catalyst used in the process according to the invention shows, in addition to its improved ability to catalyze the methanation reaction ("sulfur resistance") despite the presence of sulfur, at the same time the ability to absorb or irreversibly bind sulfur ("sulfur capacity") ,

In addition, the invention relates to a process for the methanation of carbon monoxide and / or the carbon dioxide, in a reactant stream containing carbon monoxide and / or carbon dioxide, hydrogen and more than 1 ppb sulfur, wherein the educt stream is passed through a reactor with a catalyst, wherein the catalyst comprises a Ni active composition and Mn, with a molar Ni / Mn ratio in the catalyst in the range between 1, 0 and 15.0, preferably between 2.0 and 12.0, particularly preferably between 3.0 and 10.0, or more preferably in the range between 3.5 and 5.5 or 7.5 and 9.5, characterized in that the cata- capacitor absorbs the sulfur contained in the reactant stream and simultaneously catalyzes the methanation reaction.

Furthermore, the invention relates to the use of a catalyst comprising alumina, a Ni-active composition and Mn, characterized in that the molar Ni / Mn ratio in the catalyst in the range between 1, 0 and 15.0, preferably between 2.0 and 12 , 0, more preferably between 3.0 and 10.0, or more preferably in the range between 3.5 and 5.5 or 7.5 and 9.5, for the methanation of carbon monoxide and / or carbon dioxide with gaseous hydrogen in the presence of more than 1 ppb of sulfur. Preferably, during the process of the invention, the catalyst absorbs more than 70%, more preferably more than 80%, of the sulfur present in the reactant stream, ie during the process the product stream contains 70 or 80% less sulfur than the educt stream. It is particularly preferred that during the process according to the invention the catalyst completely absorbs the sulfur in the educt stream, then the product stream no longer contains any sulfur.

The catalyst according to the invention is particularly suitable for the methanation of carbon monoxide and / or carbon dioxide by hydrogen in the presence of more than 1 ppb, preferably more than 4 ppb, more preferably more than 10 ppb of sulfur. One ppb sulfur corresponds to one billionth of the volume fraction (10 ⁹ ) of the sulfur-containing molecule, it being approximately assumed that each sulfur-containing molecule has only one sulfur atom. In particular, the sulfur content in the process according to the invention is between 1 ppb and 300 ppm, preferably 4 ppb to 10 ppm of sulfur. One ppm sulfur in this case corresponds to one millionth part by volume (10 ⁶ ) of the sulfur-containing molecule, assuming approximately that each sulfur-containing molecule has only one sulfur atom.

The methanation of carbon dioxide can be represented by the following reaction equation:

4H ₂ + C0 ₂ -> CH ₄ + 2H ₂ 0

The methanation of carbon monoxide can be represented by the following reaction equation:

3H ₂ + CO -> CH 4 + H ₂ O

The methanation is generally carried out at temperatures of 180 ° C to 600 ° C.

In the method for carrying out the methanation, the reactant gas, which contains carbon dioxide or carbon monoxide or a mixture of both, is brought into contact with the catalyst at a temperature above 180 ° C. to 600 ° C.

The catalyst contains alumina, a Ni active composition and Mn, the Ni / Mn ratio, in particular in the case of the coprecipitated catalyst, in the range between 2.0 and 6.0, more preferably between 3.5 and 5.5, or more preferably in the range between 4.0 and 5.0. Alternatively, the Ni / Mn ratio is, in particular in the case of the catalyst represented by impregnation, in the range between 6.0 and 10.0, preferably between 7.5 and 9.5 and particularly preferably between 8.0 and 9.0.

The alumina need not be stoichiometric Al 2 O 3, but may be a non-stoichiometric alumina, preferably gamma Al ₂ O 3.

The promoter Mn may be wholly or partially contained in the Ni active material. The catalyst can contain further promoters in addition to Mn, but it can also exclusively contain the promoter Mn. The oxidation states of Al, Ni and the promoters can vary depending on the treatment of the catalyst. Al, Ni and the promoters are typically present as metal cations (eg Al ³⁺ , Ni ²⁺ , Mn ²⁺ , Mn ⁴⁺ ). After calcination, eg in air, high oxidation states or the maximum oxidation states can be achieved. If the catalyst is reduced at temperatures above room temperature, for example under reaction conditions with hydrogen, Al, Ni and the promoters can assume lower oxidation states or occur partially or completely in the oxidation state O. The charge balance to the metal cations is carried out by oxygen anions (O ² ).

The catalyst according to the invention may contain other components in addition to aluminum oxide (AIO _x with x <1, 5) Ni, and Mn (as well as the Sauerstoffanio NEN necessary for charge equalization), but it can also hen exclusively from alumina, Ni and Mn best. The Ni-active composition may contain further promoters in addition to Mn, but it may also contain exclusively the promoter Mn. Preferably, the Ni active composition contains none of the elements selected from B, Ta, In, Cu, Ce, Cr, Bi, Fe, P, Sb, Sn, Si, Ti, Zr, Co, Rh, Ru, Ag, Ir, Pd and Pt. Preferably, the Ni active material contains no noble metal.

For the catalyst represented by impregnation, the atomic (ie molar) Al / Ni ratio is preferably greater than 2, particularly preferably greater than 2.7, in particular the molar Al / Ni ratio between 2 and 9 is preferably between 2.3 and 5 ,

For the catalyst shown by coprecipitation, the molar Al / Ni ratio is preferably between 0.1 and 0.9, preferably between 0.3 and 0.7, more preferably the molar Al / Ni ratio is approximately 0, 45th The catalysts according to the invention may advantageously have crystallites in the Ni active composition with a diameter of less than 20 nm, preferably less than 10 nm. The Ni active material may also be wholly or substantially of crystallites with a Diameter below 20 nm, preferably below 10 nm exist. The Ni active material is preferably present in a metallic state.

The C0 ₂ uptake capacity of the catalysts at 35 ° C may be greater than 150 pmol / g and is preferably in the range between 150 and 350 pmol / g, more preferably between 180 and 260 pmol / g.

The BET surface area (SBET) of the catalyst according to the invention may be greater than 100 m ² / g, preferably greater than 200 m ² / g, or in the range between 100 and

200 m ² / g, preferably in the range between 150 and 180 m ² / g.

The specific metal surface area (Swiet) of the catalyst according to the invention is preferably greater than 10 m ² / g, preferably greater than 20 m ² / g and preferably in the range between 20 m ² / g and 70 m ² / g. For the catalyst prepared by co-precipitation, the specific metal surface area (Swiet) is preferably in the range between 30 and 70 m ² / g, more preferably between 40 and 60 m ² / g. For the catalyst prepared by impregnation, the specific metal surface area (Swiet) is in the range between 20 and 80 m ² / g, preferably between 25 and 70 m ² / g or between 30 and 60 m ² / g. The catalyst used in the process according to the invention is preferably present in a reactor and forms a catalyst bed therein. The reactor is flowed through with the educt gas and thus comes into contact with the catalyst. At the same time, the reactor is heated so that the required reaction temperature of the catalyst is achieved.

The catalyst acts due to its increased sulfur capacity in addition to its catalytic function at the same time as a sulfur trap ("trap" function). The catalyst inlet to the reactor inlet in the catalyst bed will absorb the sulfur and thus protect the subsequent catalyst from sulfur poisoning. At the same time, the sulfur-loaded catalyst at least partially retains its activity in the methanation reaction. The catalyst used in the process according to the invention has the advantage of an increased sulfur absorption capacity, so that in addition to the function as methanation catalyst, the function is realized as a sulfur trap. As a result of the improved function as sulfur trap, the function as a methanation catalyst is subsequently increased. Ideally, the sulfur contained in the educt gas completely absorbed in the front region of the catalyst bed, so that in the rear loading area of the catalyst bed, the educt gas contains no more sulfur and accordingly there is no deactivation by sulfur sulfur. The catalyst used in the process according to the invention can be prepared by coprecipitation. In the preparation of the catalyst by coprecipitation, at least one solution containing Al, Ni and Mn in dissolved form is added with a precipitating reagent to obtain a precipitate.

The preparation of the catalysts by coprecipitation comprises, for example, the following steps:

a) co-precipitation from a solution containing Al, Ni and Mn in dissolved form to obtain a precipitate,

b) isolating the precipitate from step a),

c) drying the isolated precipitate from step b) and

d) calcining the dried precipitate from step c).

In this case, it is preferred that the solution from step a) is an aqueous solution and Al, Ni and Mn are present dissolved in the aqueous solution as ionic compounds.

Alternatively, the catalyst according to the invention can also be prepared by impregnation. Then the catalyst according to the invention is e.g. by simultaneous impregnation of nickel and manganese onto a suitable alumina support. The effect of improved sulfur resistance and sulfur capacity is observed for both precipitated (co-precipitated) and impregnated catalysts. Normally, impregnated catalysts can not be produced with as high Ni contents as precipitated catalysts, since nickel uptake during impregnation is limited by the volume of the pores of the aluminum oxide.

Surprisingly, it has been found that the sulfur capacity of an impregnated catalyst, based on the amount of Ni used, is even somewhat greater than that of a coprecipitated catalyst. This is shown in FIG. 2, for which the amount of sulfur absorbed was normalized to the weight of catalyst. Despite lower metal loading of catalyst C, there is a similar mass increase as in catalyst A. FIG. 1: Decrease in the activity of the catalysts A to C during the catalytic test reaction (test 1).

Figure 2: Mass increase by sulfur uptake of the catalysts A to C during the catalytic test reaction, normalized to the weight of catalyst (Test 1). Figure 3: Decrease in activity relative to sulfur uptake during the catalytic test reaction (Test 1, assuming nickel sulfide is formed).

FIG. 4: Decrease in the activity of catalysts A and B during the catalytic test reaction (test 2).

methods

Elemental analysis

The determination of the composition of the calcined catalysts was carried out by means of inductively coupled plasma optical emission spectroscopy (ICP-OES). 50 mg of catalyst were dissolved in 50 ml of 1 molar phosphoric acid (VWR, pA) at 60 ° C. To dissolve any brownstone formed, 50 mg Na ₂ S0 ₃ (Sigma Aldrich, pA) was added to the solution. After cooling, the solutions were diluted 1/10, added to the same concentration with Na ₂ SO ₃ and filtered by means of 0.1 pm filters (Pall). The calibration solutions were measured at 1, 10 and 50 mg l ^_1 (Merck). Determination of metal concentrations was performed using an Agilent 700 ICP-OES.

Determination of the specific surface

The specific surface area of the catalysts (SBET) was determined by N ₂ -BET analysis on a NOVA 4000e (Quantachrome). For this purpose, 100 mg of catalyst were degassed for 3 hours at 120 ° C and then adsorption and Desorptionsiso- therme in the p / p ₀ range of 0.007 to 1 recorded. To determine the BET surface area, the data points in the p / p ₀ range of 0.007 to 0.28 were used.

Hg pore volume

The pore distribution and the pore volume of the catalyst particles were determined using a mercury porosimeter: Pascal 440 from Thermo Electron Corporation according to DIN 66133. there previously, the sample was evacuated for 30 minutes at room temperature. Samples in the range of 600 to 900 mg were measured and the pressure increased to 2000 bar.

chemisorption

Chemisorption experiments were performed on an Autosorb 1C (Quantachrome). Before the measurement, 100 mg of catalyst were activated at 500 ° C in 10% H ₂ in N ₂ for 6 hours. The heating ramp was 2 Kmin ^-1 .

The determination of the metal surface (SMET) was carried out according to DIN 66136-2 (Ver., 2007-01) and was carried out by means of H ₂ chemisorption at 35 ° C. For this purpose, 20 adsorption points were recorded equidistant from 40 mmHg to 800 mmHg. The equilibration time for the adsorption was 2 min, the thermal equilibrium 10 min. To determine the metal surface, a metal atom / H stoichiometry of 1 was used. For C0 ₂ chemisorption measurements, the equilibration time for adsorption was set to 10 min with otherwise unchanged parameters. Before recording the chemisorption data, any kinetic inhibition of C0 ₂ chemisorption under these conditions was experimentally excluded. Metal surfaces and CO ₂ uptake capacities were extrapolated to a pressure of 0 mmHg according to the extrapolation method.

synthesis

The catalysts A and B were prepared by coprecipitation at a loading of 50 wt% nickel, which for catalyst A at a molar ratio of aluminum to nickel of 0.75 and for the manganese-containing catalyst B to a molar Al / Ni ratio 0 , 47 leads. To study the effect of manganese on catalyst behavior, manganese (II) nitrate was added to the salt solution of nickel and aluminum nitrate during catalyst synthesis. The purity of all chemicals used was pa Water was purified by a millipore filter system and the degree of purity verified by conductivity measurements. The synthesis was carried out in a double-walled, 3 l stirred tank. The double jacket, which was filled with water, allowed the temperature of the synthesis batch to be adjusted to 30 ° C. via a thermostat, and two flow breakers provided improved mixing. For stirring, a KPG stirrer with 150 revolutions min ^-1 was used. For the synthesis, 1H ₂ 0 was placed in the stirred tank and adjusted to pH = 9 ± 0.1. The dosage of the mixture of dissolved nitrates was 2.5 ml min ^-1 . At the same time, the controlled addition of the precipitating reagent was used to maintain the pH. As starting materials molar solutions of the respective nitrates were used (Ni (N0 ₃₎ ₂ ^* 6H ₂ 0, AI (N0 ₃₎ ₂ ^* 9H ₂ 0 and Mn (N0 ₃₎ ₂ ^* 4H ₂ 0). These were mixed in for catalyst B in a molar ratio of Ni to Mn of 4.6 to 1 and of Al to Ni of 0.45 to a total volume of 120 ml min ^-1 before the dropwise addition to the reactor took place. The precipitation reagent used was a volume-identical mixture of the solutions 0.5M NaOH and 0.5M Na ₂ C0 ₃ , for the metering of which a titrator was used. With constant stirring, the suspension was aged overnight in the mother liquor, the precipitate was then filtered off and washed with H ₂ 0 until the filtrate had a neutral pH. After drying at 80 ° C in a drying oven overnight, the dried precipitate (precursor) was heated at a heating rate of 5 K min ^-1 to 450 ° C and calcined for 6 hours under synthetic air.

Catalyst C was prepared but triple impregnation each with subsequent calcination. In a 5 I beaker 3022.0 grams of Ni (N0 ₃₎ ₂ were ₂ x 4H ₂ 0 (98.5%) presented x 6H ₂ 0 (98%), 307.9 g of Mn (N0 _3). With deionized water was made up to a volume of about 2900 ml and stirred by means of propeller stirrer until a clear solution was present. It was then made up to the required total volume of 3441 ml with deionised water.

First impregnation: A sealable container was charged with 1879.3 g of gamma alumina 1/8 "extrudates (equivalent to 3.6 l, bulk density 522 g / l, loss on ignition 4.22%), and slowly and in small quantities 1349 ml of impregnating solution, which corresponds to the maximum amount of solution which does not yet form a supernatant solution, and was then closed and shaken / homogenized over and over again, when the complete solution was added, shaking for a further two minutes.

First Calcination: The impregnated extrudates were transferred to porcelain dishes and heated at 2 ° C / min to 120 ° C and dried at this temperature for 6 h in air. Thereafter, the WUR impregnated extrudates were heated at 2 ° C / min to 240 ° C and calcined in air at this temperature for 4 h.

Second Impregnation: The once impregnated extrudates were placed in a sealable container. 1 147.0 ml of impregnating solution were added slowly and in small amounts, which corresponds to the maximum amount of solution at which no supernatant solution forms. In between, the container was repeatedly closed and shaken / homogenized. When the complete solution was added, shaking was continued for a further two minutes.

Second Calcination: The impregnated extrudates were transferred into porcelain dishes and heated at 2 ° C / min to 120 ° C and dried at this temperature for 6 h in air. Thereafter, the WUR impregnated extrudates were heated at 2 ° C / min to 240 ° C and calcined in air at this temperature for 4 h. Third Impregnation: The twice impregnated extrudates were placed in a sealable container. Slowly and in small quantities, 944.3 ml of impregnating solution were added, which corresponds to the maximum amount of solution at which it does not yet form a supernatant solution. In between, the container was repeatedly closed and shaken / homogenized. When the complete solution was added, shaking was continued for a further two minutes.

Third Calcination: The impregnated extrudates were transferred to porcelain dishes and heated at 2 ° C / min to 120 ° C and dried at this temperature for 6 h in air. Thereafter, the WUR impregnated extrudates were heated at 2 ° C / min to 240 ° C and calcined in air at this temperature for 4 h.

Thermogravimetric analysis and catalytic test reaction

For the investigation of the deactivation by hydrogen sulfide the thermogravimetric analysis was used (TGA). In this case, the catalyst bed to be examined in egg nem heated, forced-flow reactor (1, 53 ml) is introduced and with educt gases (79.5 vol .-% H ₂ , 20.5 vol .-% C0 ₂ , H ₂ S content starting material 43 ppm at T = 270 ° C, p = 6 barg and SV, "Space Velocity" about 16 000 1 / h) acted upon. The flow behavior through the bed behaves similar to tubular reactors. Due to the discontinuous, contact-free weighing (accuracy = ± 10 pg) via a magnetic levitation coupling mass changes during the catalytic process can be detected. At the same time, the catalytic activity was evaluated by determining the product gas composition. For this purpose, a partial stream of the product gas was analyzed with a mass spectrometer. The results are shown under "Catalytic Test Reactions", "Test 1" and "Test 2". The experimental conditions were kept constant in order to ensure the comparability of the various catalysts investigated during the test series. Since the catalysts are obtained in an oxidic form from the synthesis, they must first be reduced in the H2 stream before starting the tests in order to produce the catalytically active, metallic phases. The reduction takes place until the weight remains constant. The specified weights of the catalysts are based on this weight after the reduction, which is lower than the original weight by the conversion of NiO into Ni or MnO ₂ in Mn: Test 1: Catalyst A: 1.27 g, Catalyst B: 0.93 g of catalyst C: 0.90 g. Shown is the normalized H ₂ conversion (0 corresponds to 0% conversion, 1 corresponds to 100% conversion).

Test 2: Catalyst A: 1.02 g, Catalyst B: 1.05 g of catalyst Examples

Example 1: Synthesis of the catalysts

Three catalyst samples were prepared according to the synthesis described in the method part, wherein catalyst A is a comparative sample without manganese, while the catalysts contain 5 B and C manganese. The three catalysts have the properties summarized in Table 1 together.

Table 1: Analytical data of the investigated catalysts

Example 2: Catalytic Test Reactions 10 Test 1

The results from T est 1 are shown in FIG. The H ₂ conversion decreases with increasing duration of the experiment and catalyst poisoning in all investigated catalysts. For catalyst A and catalyst B, each with 50 wt .-% Ni loading, the decrease in activity is very similar, however, the weight of Mn-promoted catalyst B was 0.93 g against 15 over 1.27 g for catalyst A clearly lower and the catalytic results are not normalized to the initial weight. For catalyst C, the activity decreases faster due to the nickel loading, which is only about half as large

Test 2

The results from Test 2 are shown in FIG. The CC conversion decreases as the duration of the experiment and catalyst poisoning progresses for both catalysts studied. In contrast to the results in Figure 1 was for the purpose of better comparability, worked for the two catalysts A and B with the same catalyst weigh-in of 1, 0 g and the same size of the catalyst particles. The weight of the catalyst A and the catalyst B was 1, 02 and 1, 05 g. Catalyst B shows a markedly improved deactivation behavior. According to the result from test 2, the additional result Amount of 10 wt.% Manganese in Catalyst B at approximately doubling the time to deactivation for Catalyst B over Catalyst A.

Example 3: Sulfur uptake during the catalytic test reaction

During the catalytic test reactions in Example 2, the uptake of sulfur from all three catalyst samples A, B and C was measured simultaneously. This is the Messda th in Figure 2 refer to the sulfur uptake was nor to the weight of the catalyst nor metered. Surprisingly, the uptake of sulfur in catalyst B is markedly higher than in catalyst A. Also in catalyst C, the sulfur uptake is increased in comparison to the regenerated catalyst catalyst A without manganese, although catalyst C has a significantly lower nickel loading. Surprisingly, the additional content of manganese in both catalysts B and C leads to an increase in sulfur uptake.

This observation is further confirmed by the analytical determination of the sulfur content of the catalysts after complete deactivation. The analytical results of the S uptake from the TGA test and the chemical analysis are summarized in Table 2. While the weighing of the TGA analysis provides an integral value for the amount of S taken up, the used catalyst was taken in layers after test 2 had been carried out. Via the subsequent chemical analysis, the S uptake can then be spatially resolved and a corresponding loading profile can be determined. It is clearly recognizable that the sulfur uptake in the upper part of the TGA reactor seal has the highest value of 0, the loading of sulfur decreases gradually towards the exit of the reactor. The chemi cal analysis is carried out by inductive combustion of the sample in an oxygen flow to S02 and subsequent quantitative infrared analysis of a characteristic S02 band.

Values from TGA

Values from chemical analysis

Table 2: Determination of sulfur uptake on the basis of TGA analysis and the subsequent chemical analysis of the used catalysts after removal from the experimental reactor.

In the results shown in Figure 1, the different weight of Ka catalyst in test 1 was not considered. In order to correct this, the results were normalized to the initial weight in the results shown in FIG. The results shown in FIG. 3 show that catalysts B and C are more suitable for use in sulfur-containing gas streams. In Figure 3, the x-axis corresponds to the uptake of sulfur with respect to the nickel mass present and the y-axis of the catalytic activity. It was postulated that the absorbed sulfur is bound as NiS, which, however, is not analytically proven, but was only used for clarification. As FIG. 3 shows, the catalyst B according to the invention exhibits a higher activity than the catalyst A for the same sulfur loading, and the catalyst C shows a similar activity.

Claims

claims

A process for the methanation of carbon monoxide and / or carbon dioxide, in a reactant stream containing carbon monoxide and / or carbon dioxide, hydrogen and more than 1 ppb of sulfur, using a catalyst, the alumina, a

Ni active composition and Mn, characterized in that the molar Ni / Mn ratio in the catalyst in the range between 1, 0 and 15.0, preferably between 2.0 and 12.0.

2. The method according to claim 1, characterized in that the catalyst has been prepared by coprecipitation.

3. The method according to claim 1 or 2, characterized in that the molar Ni / Mn ratio in the catalyst in the range between 2.0 and 6.0 or 3.5 and 5.5.

4. The method according to any one of the preceding claims, characterized in that the molar Al / Ni ratio of the catalyst in the range between 0.1 and 0.9, before zugterweise between 0.3 and 0.7.

5. The method according to claim 1, characterized in that the catalyst has been prepared by imprägnation of the alumina with a solution comprising Ni.

6. The method according to claim 5, characterized in that the solution comprising Ni also contains Mn.

7. The method according to any one of claims 5 or 6, characterized in that the mo lar Ni / Mn ratio in the catalyst in the range between 6.0 and 10.0, particularly preferably be between 7.5 and 9.5.

8. The method according to any one of claims 5 to 7, characterized in that the molar Al / Ni ratio of the catalyst in the range between 2 and 9, preferably between 2.3 and 5.

9. The method according to any one of the preceding claims, characterized in that the reactant stream contains more than 1 ppb, preferably more than 4 ppb, more preferably more than 10 ppb sulfur.

10. The method according to any one of the preceding claims, characterized in that the reactant stream between 1 ppb and 100 ppm, preferably between 4 ppb and 50 ppm sulfur.

1 1. The method according to any one of the preceding claims, characterized in that the Ni active material crystallites with a diameter of less than 20 nm, preferably below

10 nm.

12. The method according to any one of the preceding claims, characterized in that the catalyst has a C0 ₂ uptake capacity at 35 ° C of greater than 200 pmol / g, preferably before between 200 and 300 pmol / g.

13. The method according to any one of the preceding claims, characterized in that the catalyst at a temperature of about 150 ° C, preferably above 200 ° C, is brought into contact with the reactant stream.

14. A process for the methanation of carbon monoxide and / or carbon dioxide, in a reactant stream containing carbon monoxide and / or carbon dioxide, hydrogen and more than 1 ppb of sulfur, wherein the reactant stream is passed through a reactor with a catalyst, and the catalyst is a Ni Active composition and Mn comprises, with a mo laren Ni / Mn ratio in the catalyst in the range between 1, 0 and 15.0, preferably between 2.0 and 12.0, characterized in that the catalyst absorbs the sulfur contained in the reactant stream and at the same time catalyzing the methanation reaction.

15. The method according to claim 14, characterized in that the catalyst absorbs the sulfur contained in the reactant stream to 90%, preferably completely sorbed off.

16. Use of a catalyst comprising aluminum oxide, a Ni active composition and Mn, characterized in that the molar Ni / Mn ratio in the catalyst in the

Range between 1, 0 and 15.0, preferably between 2.0 and 12.0, more preferably between 3.5 and 5.5 or 7.5 and 9.5, for the methanation of carbon monoxide and / or carbon dioxide with gaseous Hydrogen in the presence of more than 1 ppb sulfur.