DD242184A1 - METHOD FOR PRODUCING A CUO MNO CATALYST - Google Patents

Abstract

The aim of the invention is a process for the preparation of CuO-MnO catalysts, which in addition to high activity have a high temperature stability and excellent long-term behavior. The object of developing an effective process for the preparation of a catalyst which oxidizes exhaust gases containing solvents at the lowest possible temperatures with high efficiency is achieved by precipitating copper-manganese carbonate basic catalyst and manganese nitrate solutions with ammonium carbonate as precatalyst, filtering the precipitate, washed, dried and mixed with Na2O-containing aluminum hydroxide in the ratio 1: 1 to 1: 9 and deformed, wherein the finished catalyst contains 0.1 to 0.5 Ma .-% Na2O. The catalyst is used for the oxidation of organic pollutants in exhaust gases or waste products.

Description

Field of application of the invention

The invention relates to a process for the preparation of a CuO-MnO catalyst, which can be used for the oxidation of exhaust gases in the organic pollutants and carbon monoxide to carbon dioxide and water.

Characteristic of the known technical solutions

The increasing pollution of the environment by pollutants is caused by the constantly increasing industrialization and motorization. Mainly responsible are the compounds contained in the exhaust gases such as carbon monoxide, hydrocarbons, aldehydes, anoxidized hydrocarbons, nitrogen oxides. Of the various methods now known for the removal of pollutants, the catalytic afterburning process is the most effective. By employing a catalytic converter in the exhaust system, it is possible to almost quantitatively produce the exhaust products resulting from the combustion of hydrocarbonaceous fuels or the oxidation of hydrocarbons To convert the innocuous products carbon dioxide and water and thus the ever stricter

Comply with regulations. ,

As catalysts which are thought to be effective in the reaction of exhaust products such as carbon monoxide, hydrocarbons, etc., a large number of metals and metal oxides are known. These metals and metal oxides include in particular noble metals, the oxides of copper, manganese, nickel, iron, chromium, vanadium, cobalt. Although catalysts containing noble metals as the reaction-accelerating component have high activity, they have the disadvantage of high price and sensitivity to lead.

For this reason, there is a great deal of evidence to use non-precious metals instead of noble metals as an active component for the production of oxidation catalysts for the elimination of pollutants.

Thus, for the purification of exhaust gases from internal combustion engines in DWP 81 404 supported catalysts are described. Alumina, asbestos and magnesium silicate on which a combination of copper oxide, nickel oxide and chromium oxide has been applied by impregnation are used as support material.

DD-AP 100635 uses mixtures of oxides and / or aluminates of copper, nickel and manganese. The ratio of the metals Cu: Ni: Mn is 1: 1: 1.

In DD-AP 100771 barium aluminate, calcium aluminate and strontium aluminates in admixture with silica and / or titanium dioxide and as active components copper oxide, nickel oxide and cobalt oxide are used as the carrier.

In DD-AP 111 234 serve from the metal nitrates of copper, nickel and manganese with the carrier Ci-AI ₂ O ₃ by annealing at temperatures above 1 000 ⁰ C resulting aluminates as reaction accelerators for the oxidation of carbon monoxide and hydrocarbons.

In the patent DD-AP 112905, a catalyst of the composition Cu Mn _x Me _y Cr _z O _w , where Me Co and Ni mean protected.

Very often, the catalytic effect of the non-noble metal oxides by noble metals is increased. Examples thereof are DD-AP 107603, DD-AP 110767, DD-AP 132851 and DD-PA 140110.

Addition of noble metals, however, means additional process steps in the preparation of the catalyst and deterioration of its economy.

Object of the invention

The object of the invention is a process for producing a CuO-MnO catalyst which has high activity, high temperature resistance and excellent long-term performance.

Essence of the invention

The invention has for its object to develop an effective method for producing a CuO-MnO catalyst, the solvent-containing waste gases or by-products in the production of Paraffinoxydaten at the lowest possible temperatures with high efficiency to CO ₂ and water oxydiert.Diese task is solved by the invention

Copper and manganese nitrate solutions with ammonium carbonate (if necessary with the addition of an aqueous ammonium hydroxide added) precipitated as a precatalyst bassisches copper manganese carbonate, the precipitate filtered, washed, dried and mixed with Na ₂ O-containing aluminum hydroxide in the ratio 1: 1 to 1: 9 and is deformed, wherein the finished catalyst contains 0.1 to 0.5 Ma .-% Na ₂ O.

The precipitation is conveniently carried out in the pH range of 7 to 10 and in the temperature range of 298 to 353 K.

It is advantageous if the sodium content in the finished catalyst is achieved by admixing with hydrargillite and amounts to 0.1 to 0.3% by mass. It is also favorable if the sodium content in the finished catalyst is achieved by admixing boehmite and 0.1% by mass. The molar ratio Cu: Mn is preferably 0.1 to 0.5.

It is also possible to mix copper tetramine solution with manganese carbonate. It is important, however, that a basic copper-manganese carbonate is obtained as a precatalyst. This basic copper manganese carbonate has excellent filtration properties, especially when the precipitation temperature is 298 to 353 K. The filtered pre-catalyst is washed with a little water and dried at 393 K and then calcined at 700 to 873 K.

The calcined product is mixed with alumina or alumina hydrates (subjected to a thermal treatment at 873 K) with 2 to 4% by weight of graphite and compressed into tablets. The admixture of alumina hydrates may be between 50 and 90% by mass. It is only important that Na ₂ O supplied with the alumina

is so that defined Na ₂ O contents can be achieved. ;

The advantages of the invention are as follows:

- The sodium content can be adjusted by the choice of oxide hydrates (boehmite or hydrargillite) targeted, so surprisingly a particularly high activity, in particular for the oxidation of the alcohols is achieved. This makes it possible to produce catalysts with a defined alkali content in a simple way. '.'

- Increased long-term behavior, even at working temperatures of the catalyst above 873K.

- Cheap macroporosity and increase in mechanical strength.

embodiments example 1

Preparation of the catalyst I

24.2 g of Cu (NO ₃ I ₂ -3H ₂ O) and 57.2 g of Mn (NO ₃ J ₂ -6H ₂ O are dissolved in 1000 ml of water and heated to 353 K. With vigorous stirring, within 10 minutes, First faster then slowly, cold-saturated (NH ₄ I ₂ CO ₃ solution added dropwise until the precipitation is complete and the supernatant solution has only a very faint blue color.

After cooling, the precipitate is filtered off, washed and dried to 393 K for 24 hours and then annealed at 825 K for 24 hours.

The black powder is mixed without grinding with 26 g of boehmite and compressed with 3% graphite to tablets of size 5 χ 5 mm. The strength of the tablets was 1049.9 kp / cm ² . After a further five hours of annealing at 825 K, a strength of 1 290.3 kp / cm ^{2 was} measured. The Na ₂ O content of the catalyst is 0.1 mass%.

Example 2

Preparation of the catalyst II

24, OgCu (NO ₃ I ₂ - 3 H ₂ O and 57 g Mn (NO ₃ I ₂ · 6 H ₂ O are dissolved in 1500cm ^{3 of} water and according to Example 1 with (NH ₄ J ₂ CO ₃ solution like, filtered , dried and calcined The oxidic product is mixed with 85 g of hydrargillite, compressed into tablets and annealed at 873 K for 6 hours.

The strength before annealing was 646 kp / cm ² and after annealing 778.5 kp / cm ² . The Na ₂ O content was 0.29 mass%.

Example 3

Preparation of the catalyst III

100 kg of MnCO ₃ are thoroughly mixed with a Cu (NH ₃ I ₄ CO ₃ solution having a Cu content of 109.3 g / l in a steam-heated stirred pan.) This suspension is heated with stirring to 433 K. This precatalyst is then added annealed at 673 K. To this product are added 103 kg of hydrargillite and 2% of graphite and the mixture is compressed into 6 × 4.5 mm tablets.

The strength is 641 kp / cm ² . After annealing these tablets at 873 K, the strength is 827 kp / cm ² . The Na ₂ O content was 0.3 mass%

Example 4 (Comparative Catalyst)

24.2 g of copper nitrate (Cu (NO ₃ I ₂ 3H ₂ O) and 57.2 g of Mn (NO ₃ I ₂ .6H ₂ O and 163.7 g of aluminum nitrate (Al (NO ₃ I ₃ .6H ₂ O) are dissolved in 2000 ml Dissolved water and heated to 353 K. Under strong stirring within 10 minutes, first faster, then slowly, a heated to 353K sodium carbonate solution (concentration 15g Na ₂ CO ₃ /!) Added until the precipitation is complete The precipitate was filtered off, washed and dried at 393K for 24 hours and then calcined at 825K for 24 hours.The powder was mixed with 3% graphite and pressed into tablets of size 5χ5 mm The strength of the tablets was 351 kgf / cm ² Annealing at 825K was found to have a strength of 412kp / cm ^2. The Na ₂ O content of the catalyst is 0.03 mass%.

Example 5

activity test

In a laboratory flow reactor, 2 g of the catalyst I are subjected to activity determination. The model gas contains 0.3% ($ n-haptan, the catalyst loading is 15000 h ^-1 .) After a one-hour reaction at 693K, the reactor temperature was gradually lowered and the temperature-turnover curve recorded, and after a sustained load of 723 K for 500 hours, no decrease in activity could be observed ,

Example 6

Activity Test In a laboratory flow-through reactor, 5 g of catalyst llan are tested for the oxidation of ethanol in carbon dioxide and water. The ethanol concentration was 0.6% (7). At 533 K, sales were still 96%. A continuous load of 700h at 723 K led to no decrease in activity. The decrease in activity after 5 hours of annealing at 1073 k lowers the activity only slightly. The 98% sales value was 550K.

Example 7

Activity Test Catalyst III In a laboratory reactor 5 g of catalyst III are tested according to the conditions of Example 6. After a one-hour reaction 673K, the reactor temperature was gradually lowered and recorded in temperature-turnover curve. At 443 K, sales were 93.5%.

Example 8

Activity Test Comparative Catalyst Under the conditions of Example 6, the conversion of the comparative catalyst at 613K was measured to be 91.5%. From the examples, it is apparent that the catalysts prepared according to the invention have a high activity. In addition, they have a high temperature resistance and excellent long-term behavior.

Claims (6)

Invention claim: 1. A process for preparing a CuO-Mn oxide catalyst, characterized in that from copper nitrate and manganese nitrate precipitated by precipitation with an aqueous ammonium carbonate as a precatalyst basic copper manganese carbonate, the precipitate is filtered, washed, dried and washed with Na ₂ O-containing aluminum hydroxide Ratio 1: 1 to 1: 9 is mixed and deformed, wherein the finished catalyst contains 0.1 to 0.5 Ma .-% Na ₂ O. 2. The method according to item 1, characterized in that the precipitation takes place in the pH range of 7 to 10 and in the temperature range of 298 to 353 K. 3. The method according to item 1 and 2, characterized in that the sodium content in the finished catalyst is achieved by admixing of hydrargillite and 0.1 to 0.3% Ma .-%. 4. The method according to item 1, characterized in that the molar ratio Cu: Mn = 0.1 to 0.5. 5. Method rf point 1 to 4, characterized in that the sodium content in the finished catalyst is achieved by admixing boehmite and 0.1 Ma .-%. 6. The method according to item 1 to 5, characterized in that the drying takes place at 3S3 to 423 K and the annealing at 673 to 873 K.