DD242184B1 - METHOD FOR PRODUCING A CUO MNO CATALYST - Google Patents

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 all 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 harmless products to convert carbon dioxide and water and thus meet the ever stricter 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 are numerous indications to use non precious metals instead of noble metals as an active component for the production of oxidation catalysts for the removal of pollutants.

Thus, for the purification of exhaust gases from internal combustion engines in DWP 81404, 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 DE-AS 2158746 manganese carbonate, nickel carbonate and copper carbonate are prepared separately and mixed after a thermal treatment at 300 ⁰ C with a refractory binder (cement, high-alumina cement and clay-based binder). These binders serve only as a support material to increase the strength. In DE-AS 1 299 606 highly annealed, inert oxides, such as MgO, Ci-Al ₂ O ₃ or silicates are used as support materials to which the active components Cu, Mn, Ni optionally Co and Ag are impregnated in the form of the nitrates.

These processes have the disadvantage that the preparation of the catalyst precursor is complicated and leads to catalysts which are strongly inhibited in their activity by the intermixing of the refractory binder. While the ^л support component is formed in the course of the process in DE-AS 2158746, DE-AS is 1 299606 prior to a shaped support on which the active components are applied by impregnation. As a result, the amount of the possible active component is limited by the porosity of the carrier.

In DD-AP 111 234 serve from the metal nitrates of copper, nickel and manganese with the carrier 0.-Al ₂ O ₃ by annealing at temperatures above 1000 ° C resulting aluminates as a reaction accelerator 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 ₂ O _w , wherein Me means Co and Ni, protected.

Very often, the catalytic effect of the non-noble metal oxides by noble metals is increased. Examples are DD-AP 107603, DD-AP 110767, DD-AP 132851 and DD-AP 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 paraffin oxydates at the lowest possible temperatures with high efficiency to CO ₂ and water oxidized. This object is achieved by copper and manganese nitrate according to the invention with ammonium carbonate (possibly mixed with the addition of an aqueous ammonium hydroxide) precipitated as a precursor basic copper manganese carbonate, the precipitate filtered, washed, dried and with Na ₂ O-containing aluminum hydroxide in the ratio 1: 1 to 1: 9 mixed and deformed, wherein the finished catalyst contains 0.1 to 0.5Ma .-% 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 with 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 is supplied with the alumina, so that defined Na ₂ O contents are achieved.

The advantages of the invention are as follows:

- The sodium content can be adjusted specifically by the choice of oxide hydrates (boehmite or hydrargillite), so that, 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 J ₂ .3H ₂ O and 57.2 g of Mn (NO ₃ ) 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 J 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 393K for 24 hours and then annealed at 825K for 24 hours.

The black powder is mixed without grinding with 26 g boehmite and pressed with 3% graphite into tablets measuring 5 × 5 mm. The strength of the tablets was 1049.9 kp / cm ² . After annealing again at 825K for five hours, a strength of 1290.3 kp / cm ^{2 was} measured. The Na ₂ O content of the catalyst is 0.1% by mass

Example 2

Preparation of the catalyst II

24.0 g of Cu (NO ₃ J ₂ 3H ₂ O and 57 g of Mn (NO ₃ J ₂ .6H ₂ O) are dissolved in 1500 cm ^{3 of} water and precipitated according to Example 1 with (NH ₄ J ₂ CO ₃ solution, filtered, dried and The oxidic product is mixed with 85 g of hydrargillite, pressed into tablets and annealed at 873 K for 6 hours.

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

Example 3

Preparation of the catalyst III

100 kg of MnCo ₃ are thoroughly mixed with a Cu (NH ₃ J ₄ CO ₃ solution having a Cu content of 109.3 g / l in a steam-heated stirred pan.) This suspension is heated to 433 K with stirring 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 J ₂ 6H ₂ O and 163.7 g of aluminum nitrate (Al (NO ₃ J ₃ 6H ₂ O) are dissolved in 2000 ml of water and heated to 353 K. With vigorous stirring, within 10 minutes, first faster, then slowly, a soda solution (concentration 15 g Na ₂ Co ₃ /!) heated to 353 K is added until the precipitation is complete. washed and dried at 393 K for 24 hours and then annealed at 825 K for 24 hours

Powder is mixed with 3% graphite and pressed into tablets measuring 5 × 5 mm. The strength of the tablets was 351 kgf / cm ² . After repeated annealing at 825 K, a strength of 412 kgf / cm ^{2 was} determined. The Na ₂ O content of the catalyst is 0.03% by weight.

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-heptane. The catalyst loading is 15,000 h ^-1 . After one hour of reaction at 693 K

the reactor temperature is gradually lowered and recorded the temperature-turnover curve. After a continuous load at 723 K for 500 hours, no decrease in activity was observed.

Example 6

activity test

In a laboratory flow-through reactor, 5 g of catalyst II are used to oxidise ethanol to carbon dioxide and water

tested. The ethanol concentration was 0.6% (-). At 533K, sales were still 96%. A continuous load of 700h at

723K 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 the catalyst III are tested according to the conditions of Example 6. After reaction for one hour 673K, the reactor temperature was gradually lowered and recorded in temperature-turnover curve. At 443K, sales were 93.5%.

Examples

Activity Test Comparative Catalyst

Under the conditions of Example 6, a conversion of 91.5% was measured at 613 K on the comparative catalyst.

From the examples it is apparent that the catalyst according to the invention have a high activity. In addition, they have a high temperature resistance and excellent long-term behavior.

Comparative Example. .

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) are dissolved in 1000 ml of water and heated to 353 K. With vigorous stirring, the mixture is first stirred for 10 minutes faster then slowly, cold saturated (NH ₄ I ₂ CO ₃ solution dripped in until the precipitate is complete and the supernatant solution has only a very faint blue color After cooling, the precipitate is filtered off, washed and dried at 393K for 24 hours and then to 825K Annealed for 24 hours.

The black powder is mixed with 26 g of gamma alumina containing only 0.01% by mass of Na ₂ O, ground and, after admixing 3% of graphite, shaped into tablets 5 × 5 mm. The strength of the tablets was 524 kp / cm ² . After annealing at 825 K, the strength was 493 kp / cm ² . The tablets were soaked with a 0.45 N NaNO ₃ solution before annealing at 825 K, the tablets being saturated completely. After drying at 393 K and annealing at 825 K, the Na ₂ O content was 0.5% (in parts by weight).

Tablet 1

activity test sales % (Ethanol conversion) accordingly % at K 96% Example 6 after 5 hours of annealing 98% 533 K 97.3% at 1073 K 98.0% 533 K 98.0% at K 97.8% Cat. I 495 K 94.8% 550K 91.3% Cat. Il 542 K 95.0% 550K 88.1% Cat. Ill 588 K 550K Vergleichskat. 1 550K Vergleichskat. 2 550K

Claims (3)

1. A process for preparing a CuO-MnO catalyst, wherein from copper nitrate and manganese nitrate precipitated by precipitation with an aqueous ammonium carbonate solution as a precatalyst basic copper manganese carbonate, the precipitate is filtered, washed, dried and calcined, this precatalyst mixed with an aluminum compound, deformed and annealed again, characterized in that the precipitation of the carbonates in the pH range 7 to 10 and in the temperature range from 298 to 353KK and the molar ratio of Cu to Mn 0.1 to 0.5, the precipitate at 393 to 423 K dried and annealed at 673 to 873 K and so mixed with Na ₂ O-containing aluminum hydroxide in a ratio of 1 to 1 to 1 to 9 that the finished catalyst contains 0.1 to 0.5 Ma .-% Na ₂ O. 2. The method according to claim 1, characterized in that the sodium content in the finished catalyst is achieved by admixing of hydrargillite and 0.1 to 0.3 wt .-%. 3. The method according to claim 1 and 2, characterized in that the sodium content in the finished catalyst is achieved by admixing boehmite and 0.1 Ma .-%.