FI58445B - CATALYST CONVERTER SELECTIVE AVLAEGSNANDE AV KVAEVEOXIDER FRAON AVFALLSGASER OCH FOERFARANDE FOER DESS FRAMSTAELLNING - Google Patents

Description

U.-y-l rBl ANNOUNCEMENT Q

UTLÄGGN INGSSKRIFT 5 8 4 4 5 C (45 \ Patent cytnneity 10 C2 1081 Patent ncdiolat ^ (51) K ».ik.3 / i« .a.3 B 01 J 23/34, B 01 D 53/36 ENGLISH— FINLAND (21) ** · η «ΙΝΙ» «» ιι »—r * t« i »ti« »etali» * lllb / 'jk (22) HakamtapUvt — AMeMnpdag 05.06.71 * (Fl) (23) Alkvpaivl— GIMgh «C * dag 05.06.7 ^ (41) Tulta Julktata * —BHvlt offuntllg 06.12.75

Patent ·] i Registry Board ^ Nihtlviksiptnon | t kuLJuHatsun pvm. -.

Patent · OCh ragisterttyralsan AmMcui uttafd oeh utlskrlftm puMkwrad 31.10.80 (32) (33) (31) Privilege claimed — Begird priority (71) (72) Gennady Alexeevich Skvortsov, ulitsa Kima, 32, kv. 50, Dnepropet-rovskoi oblast, Dneprodzerzhinsk, Nellya Nikitichna Nizeeva, ulitsa Lermontova 17, kv. U, Dnepropetrovskoi oblasti, Dneprodzerzhinsk, Avrum Iosifovich Podzharsky, ulitsa Juzhnaya, 12, sq. Km. 10, Dnepropetrovskoi oblasti, Dneprodzerzhinsk, Irma Viktorovna Dobrovolskaya, ulitsa Prokhodnoitupik 3, kv. 2-a, Dnepropetrovskoi oblasti, Dneprodzerzhinsk, USSR (SU) (7 * 0 Oy Kolster Ab {5U) Catalyst for the selective removal of nitrogen oxides from waste gases and a process for its preparation

The invention relates to a catalyst for the selective removal of nitrogen oxides from waste gases and to a process for its preparation.

The catalyst of the invention can be used to remove nitrogen oxides from waste gases in various industries, such as the production of nitric and sulfuric acid, ammonia and sodium nitrite, and in a variety of organic synthetic fields.

It is known that in the production of nitric acid, the incomplete conversion of nitrogen oxides to nitric acid results in the waste gases containing 0.05-0.5% by volume of nitrogen oxides and 3-6 by volume of # oxygen.

The concentration of nitric oxide in the waste gases in many organic synthetic industries can be as high as 1 vol.

These waste gases cannot be released into the ambient air for health reasons without first removing nitrogen oxides.

Known processes for the catalytic purification of waste gases from nitrogen oxides in the presence of nitrogen-reducing agents, which include combustion gases such as hydrogen, carbon monoxide, methane and other saturated hydrocarbons, use catalysts containing rare metals such as palladium, platinum, ruthenium. In this case, in addition to nitrogen oxides, oxygen is also removed from the waste gases. This results in a significant increase in the consumption of reducing gases.

It is known that ammonia can selectively react with nitrogen oxides in the presence of oxygen. In this case, selectivity means the possibility of controlling the process by reducing nitric oxide with a catalyst in the presence of oxygen, regardless of the amount of oxygen in the original impure gas. However, the selectivity of the process depends on the type of catalyst used.

Catalysts for the selective removal of nitrogen oxides from waste gases in the presence of ammonia gas are known in the art and contain platinum group metals.

The disadvantage of these catalysts is the considerable reduction in their efficiency under the influence of ammonia. In addition, these metals are difficult to obtain and expensive.

Cobalt, nickel and iron oxides are also known to be used as catalysts for the selective removal of nitrogen oxides from waste gases in the presence of ammonia, tableted catalysts such as vanadium, manganese, iron oxides and molybdenum and zeoxide, mixtures of manganese oxides and copper and manganese chromites.

In the preparation of the vanadium oxide-containing catalyst, the starting salt-ammonium metavanadate is decomposed at 350 ° C. The vanadium pentoxide formed is mixed with an organic binder such as glue and compressed into tablets.

The known process for the selective, catalytic purification of waste gases from nitrogen oxides in the presence of ammonia gas using the above-mentioned catalysts is carried out at a temperature of 20-100 ° C, preferably 250 ° C with a waste gas flow rate of 3000-100,000 h 1, using 1.5 ~ 2 times the stoichiometric and wherein the volume ratio of ammonia to nitrogen oxides is 1.5-1.9-

However, the degree of purification of the waste gases from nitrogen oxides with the above-mentioned excess of ammonia and these catalysts is too small or a narrow temperature range is required to achieve a sufficiently high degree of purification of 92-9%.

3,58445

A catalyst for the selective removal of nitrogen oxides from waste gases is known in the art, which comprises vanadium oxide precipitated on a neutral support, such as corundum, silicic acid or α-AlpO 2. This catalyst is prepared by impregnating the support in vanadium-containing brine, drying and calcining the support until vanadium oxide is obtained.

When purifying waste gas, the composition in volume percent is as follows: 0 ^ -3.5; N0-0, ^ 3; With the remainder being NH 4 -O 2, nitrogen in the presence of a catalyst containing vanadium oxide in an amount of 6.8% by weight, precipitated on the sediment at a waste gas flow rate of 10,000 h, the purification rate is 88.9% at 170 ° C, 97.5% at 220 ° C and 99.2% at 258 ° C.

In the case of purification of waste gas having the following composition in volume percent: Op-2.9 “3.3, NO0-0.2l * -0.26, the remainder being in the presence of a catalyst containing nitrogen vanadium oxide precipitated on Of-AJ ^ O ^, with a waste gas flow rate of 10,000 h, the purification rate is 88.9% at 170 ° C, 97.5% at 220 ° C and 99.2% at 258 ° C.

When cleaning waste gas with the following composition in volume percent: 0 £ -2.9-3 »3» N0-0.2U-0.26; NH3 ~ 0.5, the remainder being nitrogen, in the presence of a catalyst containing vanadium oxide precipitated on <X-Alp0_ at a waste gas flow rate of 20,000 h and an excess of ammonia of 2.19-2.1 * 8 times the stoichiometric amount, the degree of purification of the waste gas is 91 .5% at 285 ° C and 96.2% at 351 ° C.

Thus, a high degree of purity of the waste gases from nitrogen oxides in the presence of the above-mentioned catalysts is achieved in a narrow temperature range and in the presence of a considerable excess of ammonia compared to the stoichiometric amount.

The object of the present invention is to eliminate the above-mentioned drawbacks.

The present invention relates to a modified catalyst for the selective removal of nitrogen oxides from waste gases having a high efficiency and selectivity over a wide temperature range. The invention further relates to a process for preparing this catalyst. Complete removal of nitrogen oxides from waste gases with minimal ammonia content in the purified gas.

This is achieved by using a catalyst characterized in that manganese oxide has been added to the support to increase the activity of the catalyst, with a weight ratio of metal oxides of 0.1 to 30 and a total content of metal oxides of 5 to 0% of the total weight of the catalyst.

11,58445

The preferred total content of vanadium and manganese oxides is 10-25 # of the total weight of the catalyst.

The process according to the invention for preparing the above-mentioned catalyst is characterized in that ammonium metavanadate or vanadium pentoxide is dissolved in an aqueous solution of oxalic acid vanadate and oxalate vanadine acid. , Calculated as the metal oxide ratio VgO 2 / Mn 2 O 2, is used to impregnate the neutral support, the impregnated support is dried at 110-120 ° C and calcined at U00-600 ° C, whereby impregnation, drying and calcination are carried out. successive steps are performed at least once.

The use of manganese oxide in the catalyst composition, as well as the use of a predetermined weight ratio between vanadium and manganese oxides, provides high efficiency for the catalyst according to the invention, with use in an almost stoichiometric ratio.

The process for preparing the catalyst according to the invention ensures the preservation of the strength and structure of the support surface layer and the even distribution of metal oxides on the support surface layer.

Another important advantage of the catalyst according to the invention over the known catalysts is the possibility of substantially complete removal of nitrogen oxides from the waste gases (up to 0.001-0.005 by volume) with an ammonia gas content in the purified waste gas of less than 0.01 by volume.

The catalyst according to the invention allows the process of purification of waste gases from nitrogen oxides in the presence of sulfur dioxide, chlorine and carbon dioxide while maintaining the efficiency of the catalyst.

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The catalyst is preferably prepared as follows.

The calculated amount of distilled water is poured into a reaction vessel equipped with a stirrer and the required amount of oxalic acid is then added with stirring. It should be noted that in the preparation of an oxalic acid solution having a concentration of more than 2 CO g / l, complete dissolution is not necessary because the precipitate formed gradually dissolves during the reaction of oxalic acid and vanadium-containing compounds.

Ammonium metavanadate or vanadium pentoxide is added to the solution formed by Bite with thorough stirring.

As a result of the following reaction between oxalic acid and ammonium vanadate, 2NH4VO3 + 4H2c2o4 - (nh4) v202 (c204) 3+ 4H2O + 2CO2 (1) gives ammonium oxalate vanadate, which is easily soluble in water.

If the next reaction between v2 ° 5 + 4H20204 - H2 jv202; 0204 '“1 - 3H2O ♦ 2CO2 (2) vanadium pentoxide and oxalic acid, oxalate-vanadium acid is formed, which is also easily soluble in water.

To obtain a homogeneous solution, oxalic acid ammonium metavanadate or vanadium pentoxide are used in stoichiometric amounts according to reactions 1 and 2. To speed up the reaction, the solution is heated to 70 ° C.

After completion of the reaction between the reactants and removal of carbon dioxide, a calculated amount of water-soluble manganese salt is added to the solution. The manganese salt may be manganese chloride MnCl2.4H2O, manganese nitrate Μη (Ν03) 2 · 6Η20, manganese acetate Mn (CH3C00) 2.4H2O.

After thorough mixing of the resulting solution, a predetermined amount of a neutral support, previously dried for 5 hours at 110 ° C, is poured into the solution. The support material can be, for example, α-AlgO 2, γ-AlgO 2, quartz, chamotte, silica gel, etc. The support material is impregnated for 2C to 6c minutes in a temperature range of 20 to 70 ° C, depending on the type of support material. The impregnated support material is then dried at 110-120 ° C for 3-6 hours and calcined in a stream of air at 400-600 ° C for 5-10 hours. In certain cases, depending on the moisture content of the support material and the composition required of the catalyst, the impregnation, drying and calcination steps of the support material may be repeated several times.

6,58445

A process for the selective, catalytic purification of waste gases from nitrogen oxides is preferably used with reference to the accompanying drawing, which schematically illustrates a process flow diagram.

As shown in the drawing, the ammonia gas required in the process is obtained by evaporating the liquid ammonia introduced into the evaporator 2 via the pipe 1, whereby hot water or water vapor is introduced into the evaporator through the pipe 3. Ammonia gas is passed through line 4 to filter 5 to purify it of oil and catalyst dust, and is passed there through line 6 to heat exchanger 7 for heating.

The heating is carried out with steam, which is passed to the heat exchanger 7 via a pipe 8. The condensate is removed from the heat exchanger 7 via a pipe 9.

The ammonia gas is passed from the heat exchanger 7 through the pipe 10 to the mixer 11 and the waste gas containing nitrogen oxide heated to 200 ° C is led to the mixer via the pipe 12. Ammonia gas is introduced into the mixer 11 in an amount so that the volume ratio of nitrogen oxides in the ammonia gas to the waste gas is in the range of 0.7 to 1, depending on the degree of oxidation of the nitrogen.

The resulting gas mixture is passed via line 13 to a reactor 14 where nitrogen oxides are reduced with a catalyst according to the invention. The process in the reactor 14 is carried out at a temperature of 100-500 ° C, preferably 200-400 ° C, and the waste gas flow rate is 5000-100,000 h ”· * -.

The waste gas purified from nitrogen oxides is led to the outside air from the reactor 14 via a pipe 15.

The catalyst according to the invention allows the process to be used with high selectivity.

The process for the catalytic, selective purification of waste gases from the nitric acid industry is based on the catalytic reduction of nitrogen oxides with ammonia according to the following reactions: 4 NHj + 6 NO - 5 N2 + 6 H2O + 430 Kcal (3) 8 NH3 + 6 NO2 = 7 N2 + 12 HgO + 663 Kcal (4)

Simultaneously, a side reaction takes place when the ammonia is oxidized with the oxygen in the waste gas catalyst: 4 NH 2 + 3 02 - 2 N 2 + 6 E 2 O + 303 Kcal

The relationships between the rates of reactions (3), (4) and (5) depend on the volume ratios of ammonia and nitrogen oxides in the waste gas, the type of catalyst used and the process temperature and are largely independent of the oxygen content.

When the catalyst according to the invention is used in the process at a temperature of 200-400 ° C, the concentration of nitrogen oxides in the purified gas is at the level of 0.005 by volume, with its concentration in the starting gas being 0.1-0.4 by volume.

The performance of the catalyst according to the invention is not affected by sulfur dioxide, chlorine and carbon dioxide when their concentration in the waste gas is as high as 0.4% by volume. This allows the use of a method to remove nitrogen oxides from the waste gas in the presence of the above impurities.

The invention will be better understood from the following examples which illustrate the preparation of a catalyst according to the invention and a process for the selective, catalytic purification of waste gases from nitrogen oxides using a catalyst according to the invention.

Example 1

To prepare a catalyst having the following composition (by weight #): V 2 O 2 -1; MngOj-10O y-A120j-89; vanadium and manganese are not ok with a total content of 11% by weight * and a weight ratio * 0.1; an aqueous solution of oxalic acid at a concentration of 21.9 g / l is prepared by dissolving 3.07 g of oxalic acid in 100 ml of distilled water and 1.42 g of ammonium metavanadate are added to the resulting solution with stirring. 27.8 g of manganese chloride are then added to the ammonium oxalate-vanadate solution formed so that the weight ratio between the ammonium oxalate-vanadate and the manganese salt, calculated on the basis of the metal oxide ratio VgO2 / MngO2, is 0.1. After the manganese chloride has dissolved, 100 g of a support material - γ-ΑΙ ,, Ο ^ - which has been pre-dried at 100 ° C for 5 hours are poured into the solution. The support material is impregnated at 30-40 ° C.

After impregnation for 40 minutes, the support material is dried at 11C-120 ° C and calcined at 400-600 ° C. Samples of the catalyst with a particle size of 2-3 mm were examined in a laboratory apparatus at normal atmospheric pressure at a gas flow rate of 10,000 h by reducing nitrogen oxides with ammonia.

The experiments used an artificial gas mixture containing (% by volume): NO-0.2-0.3; NOG-0.1 to 0.12; NH ^ -0.34 to 0.50; 02-4-6, with the remainder being nitrogen.

Volume ratio of ammonia to nitrogen oxides

VNH

(-2-) VNO + NOg in the gas mixture was 1.1-1.2.

8 58445

The gas mixture described above was passed through the catalyst bed at various temperatures. The concentration of nitrogen oxides in the purified gas was determined to evaluate the degree of purification. The results thus obtained show that in the temperature range of 200-320 ° C the purification from nitrogen oxides was $ 96-98 and the selectivity of the catalyst was 85-90. Temperature Degree of purity Selectivity ° C and 200 96 90 240 97 85 260 98 85 280 98 85 320 '97 85 36c 90 80

Example 2

To obtain a catalyst having the following composition (by weight - $): VgO 2 -6; MngO ^ o; γ-ΑΙ ^ Ο ^ -θθ, with a total content of vanadium and manganese oxides of 12% by weight and a weight ratio of V20 ^ / Μη20 ^ «1, an aqueous solution of oxalic acid with a concentration of 133 g / l is prepared by dissolving 18.6 g of oxalic acid in 1G0 ml: distilled water and to this are added 8.65 g of ammonium meta-vanadate and 16.82 g of manganese chloride with successive stirring. The weight ratio of ammonium oxalate vanadate to manganese salt in the resulting solution, based on the metal oxide ratio Vo0_ / Mno0, is 1.

^ 5 ^ 3

The catalyst was prepared and tested as in Example 1.

Temperature Degree of purity Selectivity ° C and 200 82 100 240 94 88 280 97 85 320 92 83 360 90 80

Example 3

As described in Example 1, a catalyst was prepared having the following composition (by weight - #): V 2 O 2 -1-Μ $ 20 x -0.5 x Y-AlgO 2 -84.5, with a total content of vanadium and manganese oxides of 15 , 5 by weight # and weight ratio "^ O ^ / MngOj - 30.

Respectively, 22.25 g of ammonium metavanadate and 1.45 g of manganese chloride were successively dissolved in 100 ml of an aqueous solution of oxalic acid having a concentration of 9,584,450 g / l. The weight ratio of ammonium oxalate vanadate to manganese salt in the resulting solution, calculated according to the metal oxide ratio V-O 2 / Mn 2 O, was 2 5 23 30.

The catalyst was prepared and tested as described in Example 1. According to the values obtained, the purification from nitrogen oxides in the temperature range 140-400 ° C was 92-99 # and the selectivity 75-100 # Temperature Degree of purity Selectivity ° C # # 12C 88 100 140 95 100 16c 98 98 180 97 98 200 99 95 300 97 88 400 92 75 500 90 70

Example 4

To prepare a catalyst having the following composition (w / w): V205-30j Μη ,, Ο ^ -ΙΟ} γ-AlgO60, with a total content of vanadium and manganese oxides of 40 wt% and a weight ratio of V20, - / Mn20j «3; was dissolved in 300 ml of an aqueous solution of oxalic acid having a concentration of 290 g / l, 55 g of ammonium metavanadate and 35 8 of manganese chloride in succession.

The weight ratio of ammonium oxalate-vanadate to manganese salt, calculated according to the weight ratio of metal oxides Ί ^ Ο ^ / Μη ^^, was 3 «The catalyst was prepared as described in Example 1 and the impregnation and subsequent steps were repeated once more after quinination.

The formed catalyst was tested as described in Example 1. The degree of purification from nitrogen oxides was 97 # 280 ° C.

Example 3

A catalyst having the following composition (by weight #): Mn 2 O 2 -1; γ-Α120 ^ -95 »with a total content of vanadium and manganese oxides of 3% by weight and a weight ratio of V20 ^ / lfa20j - 4; was prepared as described in Example 1 by dissolving in 100 ml of an aqueous solution of oxalic acid having a concentration of 87 g / l, 5 * 6 g of ammonium metavanadate and 2.63 g of manganese chloride. The weight ratio of ammonium oxalate-vanadate to manganese salt in the resulting solution, calculated according to the metal oxide ratio νο0,. / Μηο0, was 4 · The catalyst was prepared and then tested as in Example 1. The degree of purification was 96 # 280 ° C.

10 5 84 4 5

Example 6

Catalyst having the following composition (w / w): Vo0, - 4 * Mn „0, - c 5 2 5 1; quartz - 95 * with a total content of vanadium and manganese oxides of 5 w / w and a weight ratio of V20,. / Mn20j = 4; was prepared and assembled as described in Example 1.

The degree of purification was ΘΘ # 280 ° C.

Example 7

Catalyst having the following composition (w / w): V 2 O 4 -4; Mn20j-lj silica gel - 95, with a total content of vanadium and manganese oxides of 5% by weight and a weight ratio of V20 ^ / Mn20 ^ = 4 »was prepared and assembled as described in Example 1.

The degree of purification was 92 # 280 ° C.

Example 8

A catalyst having the following composition (w / w): V 2 O 4 -4 Mn 2 O 3 -jj chamotte - 95 * with a total content of vanadium and manganese oxides of 5 wt% and a weight ratio of V 2 O 4 / Mn 2 O 3 * 4 * was prepared and formulated as described in Example 1. .

The degree of purification from nitrogen oxides was 90 # 280 ° C.

Example 9

A catalyst having the following composition (w / w) was prepared: with a total content of vanadium and manganese oxides of 5% by weight and a weight ratio of VgO 2 / MngO 2 to 4} was prepared and was prepared as described in Example 1.

The degree of purification from nitrogen oxides was 95 # 280 ° C.

Example 10

The catalyst, the composition of which is shown in Example 4, was prepared as described in Example 4 by dissolving in 300 ml of an aqueous solution of oxalic acid having a concentration of 290 g / l, 42 g of vanadium pentocide and 35 g of manganese chloride.

The catalyst formed was tested as described in Example 1. »

The degree of purification from nitrogen oxides was 98 # 280 ° C.

Example 11

The catalyst shown in Example 3 was prepared as described in that example by sequentially dissolving in an aqueous solution of oxalic acid having a concentration of 350 g / l, 22.25 8 ammonium metavanadate and 2.09 8 manganese nitrate. The catalyst was prepared and then tested as described in Example 1. The degree of purification from nitrogen oxides was 9Θ # 280 ° C: sBa.

Example 12

The catalyst shown in Example 3 was tested as described in Example 1 at 11,584,445 by volume ratios of various ammonia nitrogen oxides in the crude gas.

According to the values thus obtained, with an oxidation degree of nitrogen oxides of 30%, the optimal volume ratio between ammonia and nitrogen oxides is 1-1.1. Under these conditions, the degree of purification of the waste gases from nitrogen oxides was 95.6-97.6% with an ammonia content of 0.003-0.005 by volume of the waste gas.

V Nitrogen oxides and ammonia content Purification H3_ residual volume s% ___ degree%

V

NO + ΝΟ ^ Before contact After contact ppf IC 1 no + no2 nh3 NO N ^ 0. 9 0.1U 0.126 0.022 0.0015 8U, 5 1.0 0.16 0.16 0.007 0.003 95.6 1.1 0.20 0, 22 0.005 0.005 97.6 1.2 0.22 0t26k 0.002 0.02 99.3 1, U 0.18 0.252 0.002 0.0U 99.0

Example 13

The catalyst shown in Example 1 was tested as described in Example 1 at 260 ° C at different waste gas flow rates.

According to the values thus obtained, the degree of purification of the waste gas from nitrogen oxides was 96.8-99.5% with gas flow rates in the range of 10,000-50,000 h. The concentration of nitrogen oxides and ammonia in the waste gas was purified.

in the waste gas. volume______ degree% 3_ speed W h __ VN0 + N0o Night contact After contact 2 pp pr c 'NO + NOg NIL ^ NO NH ^ 10000 0.217 0.231 0.0033 0.0055 98, U 1.06 20000 0.137 0.157 0.0017 0 .0270 98.7 1.1¾ 30,000 0.108 0.121 0.0005 0.0135 99.5 1.12 50000 0.152 0.168 0.0050 0.0171 96.8 1.1 80000 0.100 0.118 0.020 0.011 + 0 80 1.18 12 58445

Example 1¾

The catalyst was prepared as described in Example 3 and tested in a stream of industrial waste gases at a flow rate of 20,000 Hm ^ / h at an absolute pressure of 3.5 atmospheres.

Gas composition (volume #): N0-0.08-0.20; ΪΚ -Ο ^, ^ Οΐ -Ο, ΙΟ; 0 ^ -¾-5; H ^ O 1 '2; the rest being nitrogen.

The results of the tests performed on an industrial scale are shown in the following table.

Exhaust Gas Gas Temperature Nitrogen Oxides and Ammo- Purification- V

flow C niacid concentration waste degree # ^ 3

speed W, h in gas, vol .- # ~ V

‘N0 + N03

Ehnen Kb s ket uk- Ehnen Contact after ice contact cno + no2 c'no cnh3 6500 269 295 0.295 0.0057 0.008l 97.5 1.09 15000 261 270 0.116 0.00 ^ 6 0.0057 96 1.08 30000 263 276 0.12¾ 0.003¾ 0.007 97.3 1.2

Example 15

The catalyst prepared as described in Example 3 was used to treat the waste gas passing through it with a gas composition of the following (v / v): 302-0.0¾5-0.166; NO 0.110; NH3-0,11-0,12; Og-10O with the remainder being nitrogen, at a flow rate of 10,000 h 2 at various temperatures.

The degree of purification of the waste gas from nitrogen oxides was 99.8 # 200 ° C and 98.2 # 320 ° C.

t ° C Nitrogen oxides, ammonia and sulfur content VN Purification waste gas, volumetric # _3 degree # ---- v

WELL

Before contact After contact CCCC 'C' f 1 SO2 NO υΝΗ3 ^ SOg ^ NO L NH3 200 0.127 0.101 0.110 0.130 0.0002 0.0005 1.1 99.8 280 0.0¾ 5 0.115 0.120 0 ^ 5 0.002 0.005 1, 05 98.1 320 0.166 0.110 0.110 0.166 0.002 0.007 1.0 98.2 13 58445

Example 16

The catalyst shown in Example 3 was used to treat the waste gas passing therethrough with the following gas composition (v / v): Cl2-0.113-0.330i Η ^ -Ο, ΙΟΟ; NH 2 -O 2 O 2 O 2 ~ 21; the remainder being nitrogen, at a flow rate of 10,000 h at 350 ° C. The degree of purification of the waste gas from nitrogen oxides was 9-100%.

Content of nitrogen oxides, ammonia, and chloride V Purification volume as # __3%%

V

N0_

Before contact After contact 2 n tn n O * p · P · ci2 CN02 ° nh3 0 C12 NO2 u nh3 0.330 0.103 0, 0.1U 0.330 0.002 0.00 1, U 97.7 0.113 0.096 0, 0.10 0.000 0.00060006 l , u 100

Claims (3)

1U 58445 Patents: A catalyst for the selective removal of nitrogen oxides from waste gases in the presence of ammonia as a reducing agent, which comprises vanadium oxide on a neutral support, characterized in that manganese oxide is added to the support to increase the activity of the catalyst at a total metal oxide weight ratio of 0.1-30 ~ ^ 0% of the total weight of the catalyst. Catalyst according to Claim 1, characterized in that the total content of vanadium and manganese oxides is 10 to 25% of the total weight of the catalyst. Process for the preparation of a catalyst according to claim 1, characterized in that ammonium metavanadate or vanadium pentoxide is dissolved in an aqueous solution of oxalic acid of 10-360 g / l, ammonium oxalate oxalate with a manganese salt of 0.1 to 30 calculated as the metal oxide ratio VpO 2 / Mn O 2, the solution is used to impregnate the neutral support, the saturated support is dried at 110-120 ° C and calcined at HO0-600 ° C, whereby and the successive steps of calcination are performed at least once.