SU1581361A1 - Method of cleaning effluent gases from nitrogen oxides - Google Patents

Abstract

The invention relates to a technology for purifying gaseous emissions from NO X, which is used in the chemical industry and makes it possible to eliminate the ammonia content in the purified emissions. Contact containing, wt.%: CUO 10.0-22.5

CR 2O 3 1.5-7.0

MN 2O 3 0.5-5.0

AL 2 O 3 65.5-88.0, is reduced by treatment with H 2 -containing gas at 230-300 ° C. Gas emissions with NOx impurities at 250-350 ° C are passed through the restored contact. When NO X appears behind the contact layer, the stage of contact recovery is repeated, then gaseous emissions are passed again. The volumetric rate of gas to be purified is 1000-20000 h -1. Contact activity, expressed as the amount of NO X converted to N 2 relative to 1 g of the contact, is 10.4-29.5 cm 3 / g. There is no ammonia in the purified gas. 1 hp f-ly, 2 tab.

Description

The invention relates to methods for purifying industrial gas emissions from nitrogen oxides by reducing them to molecular nitrogen and may find application in the chemical industry.

The purpose of the invention is to eliminate the ammonia content in the purified emissions.

Example 1. To 100 g of alumina (carrier A-1), 76 ml of an aqueous solution containing 46.02 g of copper (Cu) (NO3) 2-3H2O divalent copper nitrate, grade ChDA, 6.03 g of ammonium bichromate (NH4) 2Cr2O7, grade ChDA are added and 8.72 g of manganese nitrate divalent manganese Mn (NO3) 2-6H2O brand analytical grade, stirred until complete absorption of the solution by alumina. The contact is dried in air at 130 ° C for 2 hours and then calcined for 6 hours at 620 ° C. Ready contact has a composition, wt.%: CuO 12.5; Cr203 3.0; Mn2O3 2.0; 82.5. Contact activity tests were carried out in a flow type quartz reactor with reagent analysis using a chromatograph. Pre-contact restore, in

a current of gas containing 2.0 vol% H2 and 98.0% He. The contact is kept in the gas mixture stream at 300 ° C and a space velocity of 1000 hours until the hydrogen concentration at the outlet of the reactor reaches 2.0%, i.e., until the termination of the interaction of the liquid with the contact.

The reactor is flushed with helium to remove the reducing gas, and then a gas mixture containing 1.0% by volume of NO, 99.0% He, at 350 ° C and a flow rate of 1000 is passed through it, recording the composition of the gas at the outlet of the reactor. Within 90 minutes, only nitrogen (0.5% by volume in helium) is detected at the exit of the reactor. Then NO and N2O also appear. Thus, the contact ensures complete gas purification from NO within 90 min (the NO concentration at the output does not exceed 0.005% by volume). During this time, 24.2 CM3NO has time to react with the contact. When repeating the above operations, the restoration of the contact and the purification of gas from it with nitrogen monoxide under similar conditions recorded

00

00 05

The following amounts of converted in terms of 1 g of contact, cm3 NO / r: 21.7; 20.9; 20.9. With a further tenfold repetition of the steps of contact reduction and gas cleaning with NO from it, the amount of converted NO does not change and amounts to 20.9 cm3 NO / r. The loss of contact activity in the process of achieving stable activity is 13.6% of the initial value of 24.2 cm3 NO / r observed during cleaning.

18.0; Cr2O3 5.0; Mn2O3 2.0; AG2O3 75.0. The contact is tested under the conditions described in Example 2. The magnitude of the contact activity after it reaches a stable activity is 26.8 cm3 NO / r, the activity loss in the process of achieving a stable value is 16.5%.

Example 4. To prepare a contact per 100 g of support A-1, take, g: Cu (NO3) 2-3H2O 104.34; (NH4) 2Cr2O7 17.72;

gas on a freshly prepared sample, voin- 10 Afet (NO3) 2-6H2O 27.6. Ready contact has

composition, wt.%: CuO22,5; Cr2O3 7.0; Mn2O3 5.0; 65.5. The contact is tested under the conditions described in Example 2. The magnitude of the contact activity after achieving stable activity is 29.5 cm3 NO / r, the loss of activity in the process of achieving stable activity is 18.7%.

Tests of contact activity, the results of which are given in examples 1-4, are carried out with a gas flow rate at

becoming hydrogen for the first time. Upon further testing of the contact activity, the temperature of the gas reduction and purification stages is changed, leaving the rest of the test conditions unchanged. The temperatures of the stages of the process and the observed values of the time of contact reduction with hydrogen and contact activity in the process of cleaning the gas from NO are given in Table. one.

To test the activity in process 20 of the purification stage 1000. With the necessary gas purification from NO, the contact is reduced by hydrogen according to the above method at 300 ° C, and then a stream of NO2 passes through the contact layer (the content of NO2 in the gas

These volumetric gas flow rates can be increased to 15,000-20000. So, when cleaning gas containing 1.0% NO and 99.0% He, at the contact of the composition,%:

100.0%) at a contact temperature of 350 ° C and 25 CuO 12.5; CrHO3 3.0, Mn2O3 2; AF2O382.5%,

a space velocity of 25 h. For 18 min, complete conversion of NO2 into molecular nitrogen is observed, the content of NO2, NO and N2O in the purified gas does not exceed 0.005% by volume. The amount of NO2 that reacted with the contact during this time was 10.4 CMJNOz / r.

Example 2. To prepare a contact per 100 g of AF2O3 (carrier A-1), an aqueous solution is taken containing, g: Cu (NO3) 2XH2O 34.52; (NH4) 2Cr2O7 2.83 and Mn (NO3) 2X X6H2O 2.07. The rest of the method of preparation of the contact is similar to that shown in example 1. The resulting contact N2 has a composition, wt.%: CuO 10.0; Cr2O3 1.5; Mn2O3 0.5; Af2O3 88.0. The contact is tested according to the procedure described in Example 1. The composition of the gas used to reduce it by condensation with hydrogen at a temperature of 300 ° C shows complete gas purification from NO (the content of nitrogen oxides in the purified gas does not exceed 0.005%) at a space velocity of 15,000 and 350 ° C. . Activity

30 contacts under these conditions are 20.9 cm3 NO / r. The results of testing the activity of a contact containing,%: CuO 12.5; Cr2O3 3.0; Mn2O3 2.0; AG2Oz 82.5 - in the process of gas purification from NO by the proposed method are presented in table. 2. In the same table

35 shows the results of tests of a known contact containing,%: ZnO 24; Cr2O3 45; CCA 24; MPO 2; АЈ2О3 5 - in the process of gas purification according to the prototype method.

As can be seen from the table. 2, when cleaning gas

tact; H2 2; 98. The temperature is reduced from nitrogen oxides by the proposed method.

At 300 ° C, the gas volume is 1000. The initial composition of the gas to be purified,%: NO I, He 99. The contact temperature at the purification stage is 350 ° C, the volumetric gas velocity is 1000 h

AT

During the test, the steps of restoring contact and gas cleaning on it are carried out sequentially. Stable contact activity is achieved after repetition of the recovery and purification steps twice. The stable value of contact activity is 18.6 cm3 NO / r, in the process of achieving a stable value, 9.3% of the initial value for a freshly prepared contact is lost.

Example 3. To prepare the contact, take, g: AG2O3 100, Cu. (NO3) 2-3H2O 72.9, (NH4) 2Cr2O7 11.06 and Mn (NO3) 2-6H2O 9.64. The rest of the method of preparation of the contact is similar to that shown in example 1. The finished contact has a composition, wt.%: CuO

45

The only reaction product in the purified gas is molecular nitrogen, while toxic ammonia is present in the gas purified by a known method.

Claims (2)

1. A method for purifying gas emissions from nitrogen oxides by converting them into molecular nitrogen, including restoring a cycle containing oxides of copper, chromium, argan and aluminum, treating it with an hydrogen-containing gas at elevated temperature and then contacting it with the restored contact of gas to be cleaned emissions at elevated temperature, which is characterized by the fact that, in order to eliminate the ammonia content in the purified emissions, contact is used with the following content of ingredients, wt.%: 18.0; Cr2O3 5.0; Mn2O3 2.0; AG2O3 75.0. The contact is tested under the conditions described in Example 2. The magnitude of the contact activity after it reaches a stable activity is 26.8 cm3 NO / r, the activity loss in the process of achieving a stable value is 16.5%. Example 4. To prepare a contact per 100 g of support A-1, take, g: Cu (NO3) 2-3H2O 104.34; (NH4) 2Cr2O7 17.72;  Afet (NO3) 2-6H2O 27.6. Ready contact has These volumetric gas flow rates can be increased to 15,000-20000. So, when cleaning gas containing 1.0% NO and 99.0% He, at the contact of the composition,%: CCA 12.5; CrHO3 3.0, Mn2O3 2; AF2O382.5%, restored by hydrogen at a temperature of 300 ° C, see the complete purification of gas from NO (the content of nitrogen oxides in the purified gas does not exceed 0.005%) at a space velocity of 15000 and 350 ° C. Activity contact in these conditions is 20.9 cm3 NO / r. The results of testing the activity of a contact containing,%: CuO 12.5; Cr2O3 3.0; Mn2O3 2.0; AG2Oz 82.5 - in the process of gas purification from NO by the proposed method are presented in table. 2. In the same table The results of tests of a known contact containing,%: ZnO 24; Cr2O3 45; CCA 24; MPO 2; АЈ2О3 5 - in the process of gas purification according to the prototype method. As can be seen from the table. 2, when cleaning gas The only reaction product in the purified gas is molecular nitrogen, while toxic ammonia is present in the gas purified by a known method. Invention Formula 1. A method for purifying gas emissions from nitrogen oxides by converting them into molecular nitrogen, including restoring contact containing oxides of copper, chromium, argan and aluminum, by treating with water-containing gas at elevated temperature and then contacting with the restored contact of gas to be purified at elevated temperature, characterized in that, in order to eliminate the ammonia content in the purified emissions, contact is used with the following content of ingredients, wt.%: Copper (II) oxide 10.0-22.5 Chromium (III) oxide 1,5-7,0 Manganese (III) oxide 0.5-5.0 Alumina 65.5-88.0 2. The method according to claim 1, characterized in that contact recovery is carried out at 230-300 ° C, and gas emissions are contacted with the restored contact at 250-, with the recovery and contact stages being repeated. Table 1