SU1616691A1 - Catalyst for reducing nitrogen oxides with hydrogen - Google Patents

Abstract

The invention relates to catalytic chemistry, in particular a catalyst for the reduction of nitrogen oxides with hydrogen, which can be used for the purification of industrial gases. The goal is to increase the selectivity and activity of the catalyst. To do this, use a composition comprising, in wt.%: Copper oxide or zinc oxide, or strontium 0.5-5

black soot is 0.4-2.1 and iron oxide is up to 100. In this case, the degree of reduction of nitrogen oxides reaches 100% at a temperature of 280-370 ° C against 99% at 306 ° C. 4 tab.

Description

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WITH

The invention relates to catalysts for the process of reducing oxides of nitrogen with hydrogen and can be used in the disposal of waste gases of industrial enterprises.

The aim of the invention is to increase the selectivity and activity of the catalyst due to the additional content of white carbon and copper oxide or zinc or strontium with a certain ratio of components

Example 1. To prepare 1 kg of a catalyst containing 3 wt.% Copper oxide, 2 wt.% White soot and 95 wt.% Iron oxide, take 91,117 g of copper nitrate, 20 g of white soot and 950 g of iron oxide. The copper nitrate salt is dissolved in water, impregnated with this contact solution.

from iron oxide and white carbon black for 3 hours, then evaporated on sand b.apa. The resulting mixture is calcined in a muffle furnace for 4 hours, after which the granules are molded in a solution of 5 4% nitric acid.

The obtained granules are protruded in air, they are passed in a condenser cabinet with, then calcined in a muffle furnace, and the prepared catalyst is tested for activity during the reduction of nitrogen oxide with hydrogen,

Under the conditions of Example 1, catalyst compositions containing iron oxides, copper oxides and white carbon according to the invention are prepared. The research results are summarized in table 2,

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The effect of the addition of white carbon on the activity of the catalyst was preliminarily determined, for which samples were prepared with a content of white carbon from 0.4 to 2.1%

Table "1 summarizes the results of experimental data at a ratio of 1.4,

It can be seen from the tablo data that an increase in the addition of white carbon from 1 to 2.1 mass% changes the reduction degree N0j slightly, so subsequent samples of catalysts are prepared with a content of white carbon black 2%, and the content of metal oxides as active additives from 0.5 to 5 wt.%

The experimental data are summarized in tablv2, from which it is clear that the optimal amount of the additive depends on the specific conditions of the process. Under the same process conditions, an increase in the addition of copper and zinc leads to an increase in the degree of purification of the gas mixture at lower temperatures, while the addition of oxide Strontium at the same temperatures leads to a decrease in the activity associated with agglomeration of the catalyst particles But, with an increase in the process temperature to 280–370 ° C on all catalysts, ostignuta 100% cleaning degree -on

In the work on oxygen-containing gas (3.2 wt%), the process of reducing nitrogen oxides is complicated by side reactions, in particular, water formation, which is associated with additional consumption of hydrogen and a shift of the process to the area of temperature increase as a result of the release of large amounts of heat.

The tabLOZ contains experimental data obtained on a copper-containing catalyst at a volume ratio of H2 / NOj (6, oxide concentration - 0.6 mass% o (Active catalyst with oxygen content in the gas mixture, 3,, 2 mass%) o

As can be seen from tabLoZ, the effect of water vapor at 450-470 ° C has a slight effect and the catalyst is quite active, the degree of reduction of N0 at 99.5%.

Example 2: For the preparation of 1 kg of catalyst containing Zmas% zinc oxide, 2% by weight white carbon black, and

95 wt.% Of iron oxide take 69.8 g of zinc nitrate, 20.-G white and 950 g of iron oxide. Prepare the catalyst under the conditions of the example. Other compositions of this data were prepared in the same way.

Catalytic catalyst Samples of the catalyst were studied under the same conditions as the copper-containing catalyst. The results of the study are summarized in tabl2, from which

it can be seen that the catalyst exhibits high activity in the temperature range of 320-370 € depending on the content of the added additive. Increasing the additive in excess of 5% is impractical because the process shifts to higher temperatures, which leads to additional energy consumption

Example So For preparation

1 kg of catalyst containing Zmaso% strontium oxide, 2 wt.% White carbon black and 95 wt.% Iron oxide take 61.2 g of strontium nitrate, 20 g of white soot and 950 g of iron oxide. Prepare

catalyst in the conditions of example 1. "Other compositions of this catalyst were prepared in the same way. The results of his research are presented in tabLo2, from which it is clear that

actively working at 350-370 So

Table 4 presents comparative data on the activity of the prototype and the proposed catalyst. For convenience of comparison, the content of the introduced

additives are expressed in molar fractions. In addition, Table 4 shows the optimal compositions of the proposed catalyst.

The above samples of the catalyst based on iron oxide + white carbon black were studied on a gas mixture with a content of 0.6% N0, a ratio of 1.4 at a volumetric gas flow rate of 15,000 h

As can be seen from the data of Table 4, the proposed catalyst is more active than the prototype, operates at higher volumetric gas flow rates and performs a complete purification from hydroxy-

Dov nitrogen.

invention formula

A catalyst for the reduction of nitrogen oxides with hydrogen, comprising ca. 51616691

iron oxide, which is apt to be used, so that, in order to increase the selectivity and activity of the catalyst, it additionally contains white carbon and zinc oxide, shsh strontium in the following ratio of components, wt.%:

0.5-5.0 0.4-2.1 Else

Table

Catalyst

Copper oxide 3 mas% Bela carbon black 2 wt.% Oxide jelly-- for 95 mas%

The degree of recovery,%, at a temperature of 180 G 230 I 280 I 330 G 380 G 430 G 450 470

     ;. . ,

35.3 48.873.4 80.7 88.2 93.7 98.9 99.5

. Copper oxide 0,2525

Iuooo

306

10,000

400

Table 3

Table 4

1. Oxide of copper in contact 22 white sazhn (5.S)

2. Zinc oxide in contact I-2Zb.s.

0.005 0.515000 350100

0.01 1, 320100

0.03 3, 320100

97

0.05

3.0 15000 370

100

strontium in contact +22 bs 0.5 15000 350 100 1.0 370 100 3.0 370 100 5.0 370 SO

Claims (1)

Claim A catalyst for the reduction of nitrogen oxides with hydrogen, including iron • oxide, with the fact that, in order to increase the selectivity and activity of the catalyst, it additionally contains white carbon black and copper or zinc oxide, or strontium in the following ratio of components; 1616691 '* Copper or zinc oxide, or strontium 0.5-5.0 5 White soot 0.4-2.1 Oxvd iron Rest T blitz! a The content of white soot, wt. X The degree of purification from ΝΟχ, X, at temperature, C At 280 150 | 180 | 230 0.4 8.0 12.5 31,0 87.3 0.5 14.2 19.3 36.7 98.0 1,0 21.5 24.8 47.8 100 2.0 22.4 26.7 48.3 100 2.1 22.5 26.9 48.58 100 table 2 MacoX Content The degree of reduction ΝΟχ, Χ, at a temperature ° C 150 | 200 | 250 [280 | 300 1,320 | 350 j 370 Copper oxide 0.5 12.6 24.7 38.7 99.0 · “ · “ 1,0 21.5 32,0 47.8 100 ⁴ s oh 43.0 48.9 57.6 95.0 98.9 100 4,5 43.7 49.9 58.5 81.7 90.1 98.7 100 5,0 43.6 50.7 58.1 82.0 90,4 98.85 100 Zinc oxide θ, ⁵ 33.0 38.8 43,4 - 95.6 99.8 100 1,0 40.76 41.1 43.6 - 89.0 100 s oh 45.3 45.8 50.1 - 75.0 100 * '» 5,0 - - 38.8 - 64.3 97.7 98.3 100 Strontium oxide nation 0.5 28.8 29.1 38.3 - 77.3 85.0 100 1.0 31,0 32.8 43.5 - 62.7 73.0 88.3 100 3.0 12.7 17.6 29.0 - 56.3 65.5 79.9 100 5,0 10.3 16.1 22.8- - 47.0 - 78.6 99.7 Ί Table 3 Catalyst The degree of recovery, 7 _a> at a temperature 180 J 230 | 280 j 330 j 380 1 ⁴³⁰ 1 450 470 Copper oxide 3 wt.% White carbon black  > ’ 5 · > May 2, I Iron oxide'95 wt .X 35,3 48.8 73,4 80.7 88.2 93.7 98.9 99.5 Prototype Proposed The composition of the catalyst mol. Fraction wt.X Space velocity Optimal - Degree of temper- ature catalyst composition. temperature, ° C renewal,% mole fraction wt.X Volumetric speed, h ^- ' Optimal temp. Degree of restoration, X ruture, ° C Oxide copper 0.25 25 1. Oxide ι copper in contact + 2Z white soot (5.C) 0.005 0.5 15,000 280 99 Oxide chromium 0.01 1,0 15,000 280 100 0.125 2.5 0,03 3.0 15,000 320 100 Oxide cobalt 10,000 306 99 0,045 4,5 15,000 350 100 0.25 25 0.05 5,0 15,000 350 100 Oxide gland 2. Oxide zinc in contact + 2X bp 0.375 37.5 0.005 0.5 15,000 350 100 0.01 1,0 320 100 0,03 3.0 320 100 Oxide copper 0.3 thirty 0.05 5,0 15,000 370 100 Oxide chromium 10,000 400 97 0.15 fifteen 3. Oxide strontium in contact + 2X b .from. Oxide nickel 0.005 0.5 15,000 350 100 0.4 40 0.01 1,0 “Li. 370 100 Oxide gland 0,03 zo 370 100 0.15 fifteen 0.05 5,0 370 too