DD250059A5 - PROCESS FOR CLEANING GAS MIXTURES - Google Patents

Abstract

Gas mixtures are purified, especially for removal of gases which pollute the environment, such as nitrogen oxides, carbon monoxide, hydrocarbons and/or sulphur oxides from exhaust gases and flue gases, in the liquid phase by means of catalysts. According to the invention, substantial activation of the catalysts used in such processes is achieved by bringing the gases into intensive phase contact with a contact fluid containing a catalyst suspended or dissolved therein, by forming a foam from the gases and the contact fluid and allowing the reaction to proceed in the foam phase thus formed. In this way, it is possible to remove 90 to 99% of the polluting gases, present in the exhaust gases, in one working step.

Description

left, diverted a partial flow and tested for any passage through a heat exchanger on the catalyst density and, if necessary, the catalyst complements. When nitrogen oxides are removed, the gas may be admixed with a substrate which reacts with these, preferably ammonia, in a stoichiometric ratio. As such reaction substrates, besides ammonia, e.g. Carbon monoxide and hydrocarbons.

The maintenance of an intensive gas-liquid phase contact with the lowest possible pressure loss allows the execution of the inventive method on an industrial scale. To achieve this effect, in particular devices with phase contact bottoms, which help to overcome and regulate a hydrostatic pressure of the liquid column overlying this liquid are suitable. Such a device is e.g. in published PCT application WO 82/03184 (published as EP No. 73801, 16.3.1983).

It is known that metal phthalocynines can be used as catalysts for the hydrogenation of carbon monoxide to C ₁ -Cg hydrocarbons, and that cobalt or iron phthalocyanines, based on charcoal, can serve to remove nitrogen oxides from cigarette smoke. In the prior art, however, the great effectiveness of suspended in liquids or dissolved metal phthalocyanines and other catalysts in intensive phase contact with gas mixtures to be cleaned was surprising.

The inventively achieved increased activation of catalysts is of great industrial importance. Thus, with about 1,000 ppm nitrogen oxides-containing exhaust gases from power plants according to the invention using Eisenphthalocynanin at 150 ⁰ C using about 10 phase contact surfaces, an efficiency of 90% achievable, this efficiency when using a larger number of contact plates still increased and up to 99 % can be brought. For a circulation volume of 2001 carrier liquid 10kg of catalyst are required.

embodiments

Two embodiments of the method according to the invention will be described in more detail with reference to a drawing. The representation I shows the concomitant use of ammonia as a reaction substrate.

Before being introduced into the mixing space M, the waste gas is dedusted with ammoniacal solution and desulphurized. In the mixing chamber M, controlled by a probe, ammonia stoichiometrically added.

In the reaction space R, the catalyst is added as a suspension or in solution in a carrier liquid, e.g. As water, paraffin oils or silicone oils, circulated and brought in countercurrent to the exhaust gas by means of contact elements in an intensive phase contact (foam phase). The nitrogen oxides react with the added NH _{3 to form} nitrogen and water.

In the gas scrubber W, the remaining catalyst residues are washed out with purified carrier liquid from the cleaned exhaust gases and then recycled to the reaction space R.

The concentration of the catalyst is 1 to 30% by weight of the carrier liquid used, preferably 5% by weight. The temperature of the catalyst is, regardless of the catalyst, in a range of 20 to 500 ⁰ C, preferably 20 to 150 ⁰ C.

Representation II shows how ammonium nitrate can be obtained from the nitrogen oxides using the process according to the invention, NH ₃ not being introduced into the reaction space R but into the gas scrubber.

When cleaning exhaust gases from stationary diesel engines, dedusting and desulfurization is not required. The degree of de-icing in the inventive purification of such up to 10,000 ppm NO _x- containing exhaust gases by the novel process is over 90%. When increasing the current CO content of diesel engines and the exhaust gases of trucks using CO as a reaction substrate according to the invention'entstickt the CO to CO ₂ and the hydrocarbons to CO ₂ and H ₂ O are implemented.

Claims (5)

-1- Z50 059 Claims: 1. A method for purifying gas mixtures, in particular for removing environmentally harmful gases, such as nitrogen oxides, carbon monoxide, hydrocarbons and / or sulfur oxides from waste and flue gases, in the liquid phase with the aid of catalysts, characterized in that the gases with a contact liquid, the one contains in hersuspended or dissolved catalyst, are brought so in intensive phase contact by a foam formed from the gases and the contact liquid and the reaction is allowed to go in the foam phase thus formed in front of him. 2. The method according to claim 1, characterized in that the foam is formed in a column provided with phase contact bottom pillars, and the gas is preferably allowed to flow in countercurrent to the contact liquid. 3. The method according to claim 1 or 2, characterized in that aqueous catalyst solutions are used, wherein the reaction at 20 to 15O ⁰ C, preferably at 90 to 100 ⁰ C, is performed. 4. The method according to claim 1 or 2, characterized in that high-boiling liquids are used as the contact liquids, wherein the reaction at 20 to 250 ° C, preferably at 150 ⁰ C, when used for the purification of exhaust gases from internal combustion engines, however, at temperatures up to 500 ° C is performed. 5. The method according to any one of claims 1 to 4, characterized in that the contact liquid flow in countercurrent to the gas from top to bottom through the foam phase, diverted a partial flow and checked for any passage through a heat exchanger to catalyst density and, if necessary, the catalyst is supplemented , For this 1 page drawings Field of application of the invention The invention relates to a process for the purification of gas mixtures, in particular of flue gases or other exhaust gases, for. As those produced in the production of nitric acid or exhaust gases from internal combustion engines. Characteristic of the known state of the art There are known methods, according to which z. B. nitrogen oxides with the aid of catalysts and attached substances, eg. As ammonia, are removed in the gas phase. However, these investments require considerable investment. In addition, the durability of the catalysts used is limited, so that they must be renewed at least two years apart to ensure satisfactory performance. Object of the invention The aim of the invention is to avoid the disadvantages of the prior art. Explanation of the essence of the invention The invention has for its object to provide a method for purifying gas mixtures available, which allows a higher durability of the catalysts. According to the invention, these disadvantages can be bridged and 90 to 99% of the present in the gases environmentally harmful gases, such as nitrogen oxides and sulfur oxides, hydrocarbons and carbon monoxide, are removed from the gas mixtures in one operation. This is achieved in the inventive method for removing environmentally friendly gases, such as nitrogen oxides, carbon monoxide, hydrocarbons and / or sulfur oxides, from flue gases and in the liquid phase with the aid of catalysts, characterized in that the gases with a contact liquid, one suspended in it or dissolved catalyst, are brought into intensive phase contact by forming a foam from the gases and the contact liquid and allowing the reaction to proceed in the foam phase so formed. Suitable catalysts are, for. As inorganic catalysts, such as Raney nickel or platinum Mohr, or organic catalysts, eg. B. metal phthalocyanines with z. As copper, iron or cobalt as the central atom, said catalytically active materials as a suspension, for. B. platinum black or phthalocyanines, or as a solution, for. As phthaloxyanine sulfonates are used in a carrier liquid. As a carrier liquid z. As silicone oils and paraffin oils, but also other chemically inert liquids, such as quinoline, trichlorobenzene or benzophenone. When using aqueous catalyst solutions, the reaction is preferably carried out at temperatures of 20 to 150 ⁰ C, in particular at 90 to 100 ° C; when using high-boiling contact liquids at 20 to 250 ° C, in particular 150 ⁰ C, but with inventive cleaning of exhaust gases from internal combustion engines, the reaction temperatures up to 500 ⁰ C. Preferably, the contact liquid will flow countercurrent to the gas from top to bottom through the foam phase