JP2003530982A - Method for removing nitrogen oxides from an oxygen-containing gas stream - Google Patents

Abstract

(57) Abstract: A method for removing nitrogen oxides from a gas stream containing nitrogen oxides and oxygen comprises contacting the gas stream with a reducing gas stream in the presence of a NO _x removal catalyst. . Reducing gas stream, CO, comprises H _2, it may include NH _3, and the gas flow is produced by reacting a hydrocarbon with oxygen from the gas stream containing the oxygen nitrogen oxides above . A catalyst such as an oxidation or flow reforming catalyst may be used to promote the reaction that produces the reducing gas stream.

Description

Detailed Description of the Invention

The present invention relates to the catalytic conversion of nitrogen oxides produced in the combustion of hydrocarbons and / or synthesis gas (H ₂ / CO) into molecular nitrogen. More particularly, for example, in the operation of devices such as combustion engines under so-called poor or "lean burn" conditions, i.e. under combustion conditions in which excess oxygen is present, etc.
It relates to the conversion of nitrogen oxides in the presence of oxygen such that nitrogen oxides are produced. The invention further relates to the conversion of nitrogen oxides that may be produced in industrial processes such as the production of nitric acid.

In the combustion of hydrocarbons with molecular oxygen (eg from air), nitrogen oxides can be produced by temperature and pressure during the combustion process. These nitrogen oxides, especially NO and NO ₂ (usually designated NO _x ) are very harmful to the environment. Nitrogen oxides lead to the generation of acid rain and photochemical smog, among others.

Although various methods of reducing NO _x emissions are known, some of them have already been applied in practice.

Reduction of NO _x emissions in stoichiometrically operated engines is often achieved by using so-called three-way catalyst systems. The NO _x conversion catalyst in such systems reacts nitrogen oxides with reducing combustion products such as hydrocarbons and CO present in the flue gas to produce N ₂ to form harmless compounds. It is possible to convert.

Generally, three-way catalysts that reduce nitrogen oxides are not able to perform this conversion in the presence of significant amounts of oxygen.

This is a particular problem in the removal of nitrogen oxides from the flue gases of lean-burn engines such as lean-burn gas turbines, diesel engines, gas engines, and off-gases of industrial processes. This is because a large amount of oxygen is present in such a gas in addition to nitrogen oxide. Furthermore, the absence of hydrocarbons and / or CO, or the presence but in insufficient amounts, impedes the successful operation of the three-way catalyst system described above.

Therefore, in devices where there is a significant amount of oxygen in the flue gas, a certain amount of reducing agent is often added. Then, nitrogen oxides can be converted by the reducing agent in the presence of a suitable catalyst (de the NO _x catalyst). This method is known as so-called selective catalytic reduction (SCR).

Widely used reducing agents for SCR reactions are ammonia and urea.
Furthermore, it is well known from the literature to use ethylene, polyethylene and propane etc. as reducing agents (eg GP Ansell et al., Me.
chanism of the lean NO _x reaction over
Cu / ZSM-5'Appl. Catal. B, 2 (1993), p
p. 81-100 "). Other possible reducing agents are, for example, CO, H ₂ and CH ₄ , ethanol, hydrocarbons, especially fuels such as gasoline and diesel oil.

However, the most used as a reducing agent in actual SCR applications is, inter alia, ammonia or urea or an aqueous solution of urea. The use of these agents has many disadvantages. The amount used is extremely important. If,
Too much (ie, more than is needed to convert nitrogen oxides)
If ammonia or urea is loaded into the _deNOx catalyst, a so-called ammonia slip will occur. In practice, emission of ammonia from such a device, from an environmental point of view, it is even more harmful than the release of NO _x. further,
This excess usage can cause NO _x generation by the oxidation of ammonia, which is just the opposite of the intended purpose, ie reduction of NO _x emissions. Another disadvantage of using ammonia or urea is the need for their storage device and the need to replenish it on a regular basis if the supply does not occur within the limits of the battery. is there. Ammonia, in particular, is very dangerous and toxic and its transportation poses significant safety and environmental risks. All of these results in high investment and operating costs for this technology.

The selection of other reducing agents, such as the hydrocarbons mentioned above, may solve these problems to some extent, but the disadvantages such as the need for separate transportation and storage still remain. The resulting safety and environmental hazards are often unacceptable.

This problem will be solved by using the same reducing agent as the fuel used or present in the combustion process of engines, (gas) turbines, or industrial processes. However, the hydrocarbons present in diesel oil and gasoline, etc. are subject to NO _x under process conditions with acceptable rates and selectivities.
It has been found that it does not have sufficient activity for the reduction of

Known SCR catalysts are those in which the required reducing agent is first produced from a source of available hydrocarbons, for example methanol, LPG and natural gas, and optionally, H ₂ obtained from electrolysis or stored in a storage tank is added.

According to the technique described in DE-A-44 04 617, a hydrocarbon-containing fuel is catalytically cracked at 200-700 ° C. using an electrically heated reactor, the decomposition products of which are Before being added as a reducing agent to the flue gas, it is further activated by air and the entire gas stream passes through the SCR catalyst.

[0014] German published patent publication DE-A-196 00 558 also uses thermally cracked hydrocarbons as reducing agents. These hydrocarbons were obtained from diesel. According to this known method, the SCR conditions, hydrogen is added to the flue gas, heated cracked hydrocarbons to reduce NO _x through the SCR catalyst does not have a sufficiently active. Hydrogen is obtained from storage tanks or made by electrolysis or methanol reforming.

The addition of hydrogen as a reducing agent for NO _x reduction in the flue gas of successive combustion processes is described in German Published Patent Application DE-A-4230 408. Here too, hydrogen can be obtained by electrolysis of hydrocarbon-containing fuels, or by steam reforming or partial oxidation (PO). To obtain a hydrogen stream with as little carbon monoxide as possible, a two-shift reactor is placed after the reformer and most of the CO is converted with steam to produce hydrogen and CO ₂ .

The use of hydrogen produced in situ as a reducing agent for reducing NO _x from the flue gas of internal combustion engines is described in EP-A-0 537 96.
8 are described. It describes a technique for reforming hydrocarbon-containing fuels (steam reforming and partial oxidation). According to this publication, it is necessary to select the conditions so that the amount of CO in hydrogen is low so that the concentration of CO does not cause any problems regarding emission. The temperature required for reforming is achieved by using the heat of the flue gas. The reduction of NO _x is carried out through the SCR catalyst. Air is mentioned as an oxidizing agent for the partial oxidation.

According to the invention, in the reducing agent production step, the hydrocarbons are converted into a reducing agent stream under suitable conditions. Alternatively, it may be carried out by bringing a hydrocarbon into contact with the reducing agent generation catalyst. Hydrocarbons in the product stream in the reducing agent generation step are
It may be unreacted hydrocarbons from the feedstock in this step, but it may also be smaller hydrocarbons produced by the thermal cracking reaction during the reducing agent production step.

The reducing agent can be adjusted by means of a reducing agent-producing catalyst, for example from the hydrocarbon residue contained in the flue gas of the device in which the combustion takes place. It is also possible to obtain these hydrocarbons from different sources, for example combustion device fuels already available in situ. A combination of emissions and such different sources is of course also possible.
The oxygen required for this step originates, at least in part, from the offgas to be treated, that is, the gas containing nitrogen oxides and oxygen. Preferably, substantially all of the oxygen present in the offgas used to produce the reducing agent is used to produce the reducing gas stream. The hydrocarbons present in this portion of the offgas are
It is also possible to convert it into a reducing compound.

The reducing agent necessary for the catalytic reduction of NO _x , in the form of CO and / or H ₂ , which may be supplemented with hydrocarbons through a suitable reducing agent production step, optionally catalyzed, It is possible to adjust in situ from hydrocarbons and at least partially eliminate the above-mentioned drawbacks with respect to NO _x removal under oxygen-rich conditions.

In addition to the abovementioned CO and / or H ₂ reducing agents which may be supplemented with hydrocarbons,
Ammonia (NH ₃ ) can also be produced under suitable conditions in the presence of hydrogen and nitrogen due to the position of the chemical equilibrium 3H ₂ + N ₂ = 2NH ₃ .

The use of a portion of the flue gas as a hydrocarbon source and as an oxidation source for (catalytic) partial oxidation and / or steam reforming has great advantages over existing technologies. , it suppresses the emission of unburned hydrocarbons to a minimum, to reduce the oxygen content of the total flue gas flow, improved conditions for removal NO _x is, the energy present in the form of heat in the combustion exhaust gas In the catalytic step, it can be used directly without using a heat exchange layer.

[0022] Another advantage is that there is no need to generate and H ₂ containing pure H ₂ or a small amount of carbon monoxide. As a result, it is possible to dispense with shift reactor and membrane technology.

The reducing agent generation step may be a partial oxidation step using a partial oxidation catalyst. Further, for example, by controlling the amount of energy supplied to the fuel stream,
It is possible to carry out partial oxidation without the use of a catalyst, for example by means of discharge. Further, the reducing agent generation step may be a steam reforming step using a steam reforming catalyst. A combination of partial oxidation and steam reforming is also possible.

Suitable reducing agent formation catalysts are, for example, partial oxidation catalysts. In the presence of such a catalyst, partial oxidation of hydrocarbon occurs. As mentioned above, according to the invention, the oxygen required for the partial oxidation is obtained from the effluent of the combustor, even if supplemented with oxygen from other sources, such as oxygen provided by added air. Good. The product stream of the partial oxidation step is well suited for use as a reducing agent stream.

Another possibility for conditioning the stream containing H ₂ and / or CO and optionally hydrocarbons from the stream containing hydrocarbons is the use of so-called steam reforming. In steam reforming, in addition to hydrocarbons, water is added to the steam reforming step. This water may come from the exhaust of the combustion engine, from a separately stored source, or from a combination of these two sources. In steam reforming, hydrocarbons are converted with water (steam) into hydrocarbons such as methane and / or a mixture of H ₂ and CO ₂ . As a result of chemical equilibrium, CO may be present in addition to these compounds. The mixture thus produced is very suitable for use as a reducing agent stream.

Next, the reducing agent flow, together with effluent of the combustion apparatus, in contact with the de the NO _x catalyst,
The desired conversion of nitrogen oxides takes place.

The in situ generation of reducing agents offers a number of important advantages. Therefore,
According to the invention, it is possible to carry out the supply of the reducing agent continuously in the case of natural gas or in any case at the same time as the supply of the fuel of the combustion device, the reducing agent being stored and maintained separately. There is no need anymore. This is useful, for example, in mobile combustion devices such as freight cars or passenger cars. This is because, as a result of the above, no separate storage tank for the reducing agent is required. This is
It may also be an important advantage in stationary devices. A further advantage is the fact that ammonia and urea (whether in solution or not) are not used, or at least need not be obtained from others. This is because the disadvantages associated with the use of these reducing agents outlined above no longer exist.

[0028] Another advantage of the present invention occurs when hydrocarbons from the effluent of a combustor are used as a feedstock in a reducing agent production step, but as a result of such cases, the hydrocarbons become NO _x . It means that the amount of hydrocarbons in the flue gas becomes smaller because it is used in the reaction of.

Accordingly, the present invention provides a method for determining the content of nitrogen oxides in a nitrogen oxide and oxygen containing gas stream in the presence of a NOx _{decatalyst for} CO, H ₂ and, optionally, Is characterized by a method of reducing it by contacting it with a reducing gas stream containing NH ₃ , the reducing gas stream converting hydrocarbons with oxygen coming from a gas stream containing nitrogen oxides and oxygen. Obtained, which may be done in the presence of a reducing agent generating catalyst.

According to a preferred embodiment, the gas stream containing nitrogen oxides and oxygen is the effluent of the step of fuel combustion, which step comprises a stream containing one or more fuels. and a), wherein the excess oxygen with respect to fuel further comprises at least supplying step and a stream b) containing nitrogen, effluent, together with the reducing gas stream c), in contact with the de the NO _x catalyst, the Reductant gas stream c) may further comprise one or more hydrocarbons, and no ammonia and urea have been added to stream c), stream c).
Is obtained substantially by contacting streams d) and e) with a reducing agent-producing catalyst, stream d) containing one or more hydrocarbons and stream e) containing oxygen and water.

The combustor is suitable for producing heat and may be suitable for producing energy. Although the combustor operates on the basis of a flame, combustion in the combustor can also proceed by a catalytic path. Preferably, the combustion device is a gas engine, gas turbine, diesel engine or gasoline engine.

Stream c) is understood to mean that substantially no externally added ammonia and urea are present, but according to the invention it is not necessary to add a reducing agent of this type to this stream. It However, compounds such as ammonia and potentially resulting urea, may be present as a result of the N ₂ and H ₂ equilibrium reactions described above.

According to the invention, NO _x is reduced by a mixture of H ₂ , CO and optionally NH ₃ . Furthermore, hydrocarbons which have not been (fully) converted may be present in the reducing gas stream. These hydrocarbons also function as reducing agents. The reducing gas mixture is obtained by converting hydrocarbons from a portion of the flue gas stream by (catalytic) partial oxidation, steam reforming, or a combination of both techniques, which is a supplemental addition. In the combination of the above two techniques, oxygen and steam existing in the same portion as the combustion exhaust gas stream are used, and air and / or steam added from the outside may be used. . A supplemental reducing agent such as hydrogen may be added to the resulting reducing gas mixture.

Particularly preferably, in the method according to the invention, and in a device suitable therefor, the engine comprises a heat exchange device and at least part of the heat released by the combustion heats a greenhouse or other space, for example. Effectively used to. In such a device in which both heat and energy are generated simultaneously, the energy is typically in the form of electric power, but the device is called a combined heating and power supply device, or an integrated energy plant.

The present invention is further applicable to a variety of vehicles, such as ships, planes, lorries and passenger cars and trains with engines for locomotives using hydrocarbon fuels.

The method according to the invention and the device suitable for it are particularly suitable for the operation of combustion devices under so-called lean-burn conditions, which lean-flow condition a
The ratio between a) and b) is a condition in which the amount of oxygen is selected to be at least that required for complete combustion of the fuel in stream a). These are the conditions under which oxygen is present in the effluent of the combustor, under which it is possible to advantageously carry out the _deNOx reaction with the effluent of the catalytic partial oxidation step.

Suitable fuels for feedstock a) are hydrocarbons and / or syngas (CO / H ₂
Mixture).

Preferably, the hydrocarbons for the reducing agent production step are obtained, at least in part, from the same source as the fuel for the combustor. In this case, stream a) and stream d) contain the same compounds.

In order to reduce the hydrocarbon content in the exhaust of the device used in the process according to the invention, the hydrocarbons present in the effluent of the combustion device are at least partly as feedstock for the reducing agent production step. Used with or without supplementation with a hydrocarbon stream supplied from elsewhere.

[0040] In order to keep the oxygen content low and when contacting the stream above the de the NO _x catalyst, with a discharge of combustion device as an oxygen source, the supplemental by oxygen flow supplied from another go It does not have to be done.

In addition to syngas, it is possible in principle to use all hydrocarbons which are suitable as fuel for the combustor and / or as feedstock for the reducing agent production step.
However, in practice it is preferred that the hydrocarbons from streams a) and d) are natural gas (substantially containing methane), methane, diesel oil, gasoline, heavy oil, methanol, ethanol, naphtha, kerosene, ethane. , Propane, butane, LPG and their derivatives and mixtures.

The catalyst for converting the nitrogen oxides may be N 2 such as a conventional catalyst for the removal of NO _x.
The reduction of O _x from the group of catalysts which catalyze is selectable. Preferably, they are selected from the group consisting of zeolites, metal-exchanged zeolites such as Cu- and / or Ce-exchanged zeolites, Pt, Rh and / or Ir catalysts, Ba, La,
It may be provided on a carrier such as a washcoat further containing Y, Sr, Pr, Ce, Si, Ti, Al and / or Zr.

The catalyst for the partial oxidation of hydrocarbons is selected from the group consisting of Pt, Rh, Ru, Pd, CO and Ni and, if desired, Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZrO ₂ ,
It may be provided on a suitable support such as silica / alumina zeolite and mixtures thereof and stabilized with Si, La, Ba or Y and mixtures thereof.

A steam reforming catalyst capable of converting a mixture of hydrocarbons and water into a mixture of H ₂ , CO, CO ₂ and / or hydrocarbons is any conventional steam reforming catalyst. It may or may not be carried according to conventional techniques, as is well known to those skilled in the art. Preferably, the steam reforming catalyst is a supported catalyst containing Ni, Rh and / or Pt.

In order to operate the device according to the invention, factors such as the hydrocarbon / oxygen ratio, the temperature, the pressure, the residence time and / or the amount of catalyst for the partial oxidation of hydrocarbons are not completely oxidized. Should be chosen as. The hydrocarbon / oxygen molar ratio is denoted λ _PO , and the stoichiometric ratio (ie, exactly enough oxygen to achieve complete combustion of the fuel) is λ _PO = 1. According to the invention, λ _PO <1. Preferably, 0.2 <λ _PO <0.7 in lambda _PO is controlled by adjusting the amount of air / fuel, depending on the hydrocarbon used.

The temperature of the reducing agent generation step is generally 250 to 1100 ° C. The residence time in the reducing agent production step is generally 200 to 150,000 h ^-1 . Pressure will also affect, but is generally affected by other process conditions. In general, the pressure is at or slightly above atmospheric pressure, but not above 50 bar.

The use of SCR catalysts as a method of converting NO _x to N ₂ with a reducing agent often has the limitation that sufficient NO _x conversion is achievable in limited temperature flames. As an example in DE-A-19 600 558, a conversion curve of NO _x as a function of temperature is shown, in which a conversion of 40% is achieved. This is typical S that does not work with NH ₃ or urea as reducing agents.
It is a CR system. Therefore, it is advantageous to select the process conditions of the reducing agent generation step such that NH _{3 is} also generated. This is because a high NO _x conversion can be achieved.

When high NO _x conversion is required, for example when applying flue gas as fertilizer gas in horticulture, the method according to the invention uses a NO _x storage system instead of an SCR system. It is preferably performed. The NO _x removal step is performed by, for example, N. Takahashi et al. , "Environm
very high conversion of NO _x when carried out with a NO _x storage system (also referred to as NO _x storage and reduction catalyst (NSR)) as described in "Ental Catalysis p. 45 (1995)". Can be achieved. According to this method, nitrogen oxides are adsorbed from a gas stream containing nitrogen oxides and oxygen into a suitable absorbent and then, for example, by switching,
The reducing gas stream contacts the absorbent. The NO _x removal step is thus operated intermittently. Therefore, it is possible to achieve very effective NO _x removal.

This NO _x storage system allows the oxidizing medium (λ <1) and the reducing medium (λ <1
1) to absorb NO _x in the NO _x in the exhaust gas, both the absorbed NO _x can be converted into nitrogen. Catalyst in NO _x storage system is very suitably made of platinum provided in the barium-containing and / or zeolite-containing alumina wash coat. The barium present reacts with NO _x to form barium nitrate. This nitrate decomposes in the reducing medium into barium and N ₂ .

According to the present invention, the NO _x storage system comprises a NO _x storage system until the system is saturated with NO _x .
It is operable by passing the combustion exhaust gas into NO _x storage system. After that, it is possible to perform regeneration using the reducing agent obtained as described above. This reducing agent may be supplemented with reducing agents obtained from other sources.

Preferably, this NO _x storage system is designed with at least two parallel beds. One bed while being used in the absorption of NO _x, the other bed is regenerated. The former bed is saturated, and / or as soon as another bed is fully regenerated, the flow is switched, reproduced beds to continue the absorption of NO _x, bed saturated with NO _x regeneration Then, the absorbed NO _x is converted into nitrogen.

The effluent of the regeneration step of the NO _x storage bed can be effectively recirculated and can pass with the injected air through the inlet of the combustion device (eg gas engine). This offers at least two advantages. First,
In this method, it is not necessary to discharge the CO-containing gas. Secondly, according to this embodiment, in the preceding step of adjusting the reducing gas flow, CO /
Achieving complete conversion to H ₂ is not very important.

Both deNO _x catalysts and reducing agent-producing catalysts can be present in the process according to the invention in a manner well known to the person skilled in the art, for example in beds of granules, extrudates, granules and / or pellets. Can be present in the form of, or provided on a ceramic or so-called metal monolith, or in a differently structured form.

Preference is given to using a structured form of the catalyst, since this catalyst has other relevant factors for the process, such as pressure drop, mixing, contact time, heating control, mechanical strength and This is because it becomes possible to appropriately select the lifetime and the like and match it with the condition at that time, and thereby it is possible to optimize this method.

Therefore, the present invention may be in the case of generating heat from hydrocarbons and also in the case of generating energy, at which time in order to convert nitrogen oxides without the external addition of ammonia or urea. , A catalyst suitable for the conversion of nitrogen oxides, in combination with either a catalyst suitable for the partial oxidation of hydrocarbons or a catalyst suitable for steam reforming.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F01N 3/10 F01N 3/24 E 3/24 3/28 301C B01D 53/36 101Z 3/28 301 ZAB ( 81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, B G, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL , IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW (72 ) Inventor Van Iperen, René, Netherlands Erlebeek Sonnedau 7 (72) Inventor Jerez, Sice Yere, Netherlands Zwolle Prince Aleksandr Strato 22 F Term (reference) 3G091 AA02 AA04 AA06 AA12 AA17 AA18 AA19 AA20 AA21 AB02 AB05 AB05 AB BA14 CA16 CA17 CA18 FB10 GB03X GB03Y GB04X GB06W GB07W GB09Y GB16X 4D048 AA06 AB02 AC02 AC03 AC04 BA03Y BA06Y BA07Y BA08Y BA11X BA15Y BA17Y BA19X BA30X BA33X BA35X BA41X BB01 BB02 CC38 CC61 CD10 CD10 DA01 DA10

Claims (14)

[Claims] 1. A method for reducing the content of nitrogen oxides in a gas stream containing nitrogen oxides and oxygen by contacting the gas stream with a reducing gas stream in the presence of a deNO _x catalyst. , The reducing gas stream comprises CO and H ₂ , and may also comprise NH ₃ , the reducing gas stream optionally comprising oxygen and / or water from the nitrogen oxide and oxygen containing gas stream. In the presence of a reducing agent generating catalyst, if any,
A method for reducing the content of nitrogen oxides in a gas stream containing nitrogen oxides and oxygen, characterized in that it is obtained by converting hydrocarbons. 2. The method of claim 1, wherein substantially all of the oxygen present in the gas stream portion containing the nitrogen oxides and oxygen used to produce the reducing agent is depleted. 3. The gas stream containing nitrogen oxides and oxygen is the effluent of a fuel combustion step, which step comprises at least a stream a) containing one or more fuels, and And a stream b) containing excess oxygen and the effluent is contacted with a _deNOx catalyst together with a reducing agent stream c) which may further contain one or more hydrocarbons, No ammonia and urea were added to stream c) and stream c) was obtained substantially by subjecting streams d) and e) to a reductant production step, stream d) containing one or more streams. Process according to any one of the preceding claims, characterized in that it comprises a hydrocarbon of 4. Process according to any one of the preceding claims, characterized in that the gas stream containing nitrogen oxides and oxygen emerges from a combined heating and power supply unit. 5. The reducing gas stream is a partial oxidation step using a partially participating catalyst,
Alternatively, the method according to any one of the preceding claims, characterized in that it is obtained by performing a steam reforming step with a steam reforming catalyst. 6. Process according to any one of claims 3 to 5, characterized in that the fuel in stream a) comprises syngas and / or one or more hydrocarbons. 7. Process according to any one of claims 3 to 6, characterized in that streams a) and d) contain at least partially the same compound. 8. The fuel in stream a) comprises hydrocarbons, which are in stream d).
Natural gas, methane, diesel oil, gasoline, fuel oil, as well as hydrocarbons in
Methanol, ethanol, naphtha, kerosene, ethane, propane, butane, LP
Method according to any one of claims 3 to 7, characterized in that it is independently selected from the group consisting of G and mixtures thereof. 9. A reducing agent forming catalyst, which is a partial oxidation catalyst for partial oxidation of hydrocarbons selected from the group consisting of Pt, Rh, Ru, Pd, Co and Ni, and combinations thereof. A reducing agent generating catalyst is used, which may be provided on a support, which support may be stabilized by Si, La, Ba, and / or Y. The method according to any one. 10. Process according to any one of the preceding claims, characterized in that the reducing agent-generating catalyst is a steam reforming catalyst containing Ni, Rh and / or Pt. 11. Reducing agent production step is a partial oxidation step, wherein the hydrocarbon to oxygen ratio is selected such that complete oxidation does not occur, any one of the preceding claims. Method described in one. 12. Nitrogen oxides from a gas stream containing the nitrogen oxides and oxygen are adsorbed on a suitable absorbent, and subsequently a reducing gas stream is contacted with the absorbent. , A method according to any one of the preceding claims. 13. A process according to claim 12, characterized in that the absorbent is barium and / or zeolite with an alumina washcoat on a structured support. 14. The product formed in the step of contacting the structured support with stream c) is used as fuel for a gas engine.
Or the method described in 13 above.