RU2100061C1 - Catalyst for removing nitrogen oxides from gases - Google Patents

Abstract

FIELD: gas treatment. SUBSTANCE: exhausted or fresh alumino-nickel methanation catalyst, designed to remove carbon oxides from gases, is utilized as catalyst removing nitrogen oxides from gases at 150-250 C and gas volume velocities from 1000 to 4000 $$$. EFFECT: enlarged catalyst base for nitrogen oxides' removal. 1 tbl

Description

 The invention relates to alumina-nickel catalysts that can be used to purify gases from nitrogen oxides.

 Known catalysts for purification of gases from nitrogen oxides (1. Industrial catalysts of the USSR. Quick reference. Catalyst, Novosibirsk. 1988, pp. 174-182. 2. Purification of process gases. / Under the editorship of T. A. Semenova and I. L. Leites, M. Chemistry, 1977, pp. 438-443).

 These catalysts are expensive, as they are based on platinum group metals.

 Known alumina-nickel methanation catalyst (TU 113-03-398-87. Unified requirements for transportation, reception, storage, sieving, loading in apparatuses, recovery, passivation, oxidation and operation of desulfurization catalysts, natural gas conversion, natural gas conversion, carbon monoxide conversion , methanation and synthesis of ammonia. GIAP, M. 1978, S. 97-107) - prototype.

 These catalysts are designed to purify a nitrogen-hydrogen mixture from carbon oxides. Spent catalyst is not disposed of.

 The objective of the invention is the disposal of spent catalyst, the expansion of the raw material base of the catalysts for gas purification from nitrogen oxides.

The problem is solved using aluminum-nickel methanation catalyst, spent or fresh, TU 113-03-398-87 as a catalyst for the purification of gases from nitrogen oxides in the temperature range 150-250 ^o C and space velocities 1000-4000 h ^-1 .

 The use of spent or fresh alumina-nickel methanation catalyst for a new purpose is illustrated by the following examples.

 Example 1. The aluminum-nickel catalyst brand NKM-1 TU 113-03-398-87 is operated in accordance with the above uniform requirements for the production of ammonia from natural gas at an aggregate capacity of 1360 tons per day. After loss of activity, the catalyst is discharged from the methanator.

For testing, 40 ml of spent catalyst is loaded into a quartz tube with a diameter of 25 mm. The tube with the catalyst is placed in a tube furnace and heated to 150 ^o C.

For purification from nitrogen oxides, a mixture of nitrogen and air with an oxygen content in the mixture of 4.7-7.2% is taken. For dosing into the initial nitrogen-air mixture, it is preliminarily passed through a 1 liter Drexel filled with nitric acid not distant from the oxides before feeding it to the catalyst nitrogen. After passing Drexel with acid, then an empty Drexel and a Bunsen column filled with fiberglass, the nitrogen-air mixture enriched with nitrogen oxides enters the catalyst at a space velocity of 1000 h ^-1 . The content of nitrogen oxides at the inlet and outlet of the catalyst bed is determined by the photocolorimetric method. The results are shown in the table.

Example 2. Analogously to example 1, the temperature of the catalyst 200 ^o C.

Example 3. Analogously to example 1, the temperature of the catalyst is 250 ^o C.

Example 4 (control). Analogously to example 1, the temperature of the catalyst 300 ^o C, which is above the recommended limit.

Example 5. Analogously to example 3, the volumetric gas velocity of 2000 h ^-1 .

Example 6. Analogously to example 3, the volumetric gas velocity of 4000 h ^-1 .

Example 7 (control). Analogously to example 3, the gas volumetric velocity of 5000 h ^-1 , which is above the recommended limit.

 Example 8. Analogously to example 1, the catalyst is fresh NKM-1, TU 113-03-398-87.

 Example 9. Analogously to example 2, the catalyst is fresh.

 Example 10. Analogously to example 3, the catalyst is fresh.

Example 11 (control). Analogously to example 8. The temperature of the catalyst 300 ^o C, which is above the recommended limit.

The data in the table show that the use of spent aluminum-nickel catalyst for purification of gas from nitrogen oxides at a temperature of 150-250 ^o C and a space velocity of 1000 h ^-1 (examples 1-3) provides a degree of purification of 76.0-100% with increasing temperature above the proposed (example 4) the degree of gas purification is reduced by 45-21%
On the spent catalyst while maintaining the temperature at the optimum level (examples 5 and 6), the possibility of increasing the volumetric gas velocity to 4000 h ^{-1 was established} . With a further increase in the space velocity beyond the proposed limits (example 7), the degree of purification decreases to 36.3%
On a fresh catalyst (examples 8-10), when the nitrogen oxides at the inlet change from 384 to 2222 mg / m ^{3, the} degree of purification is 86.8-89.6%. When the catalyst is heated above 250 ^o C (example 11), similarly to spent catalyst, the degree of purification is reduced by 31.5-28.7%
Thus, an aluminum-nickel methanation catalyst can be used for purification of process and exhaust gases from nitrogen oxides.

Claims (1)

The use of spent or fresh alumina-nickel methanation catalyst intended for purification of gases from carbon oxides as a catalyst for purification of gases from nitrogen oxides at 150-250 ^° С and space velocities of 1000-4000 h ^{- 1} .

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