DE1266279B - Process for the production of porous silver and copper catalysts - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

BOIj

C07d

German class: 12 g -11/20
12 ο-5/05

Number: 1 266 279

File number: E 24919 IV a / 12 g

Filing date: May 30, 1963

Open date: April 18, 1968

For the oxidation of organic compounds, noble metal catalysts, such as Silver catalysts or copper catalysts are used. Usually these are catalysts made so that ceramic or other supports, which may be porous or compact, by suitable Process are coated with a layer of catalytically active metal. With silver catalysts the application of the coating can be done e.g. by impregnation or by slurrying a silver or silver oxide suspension and optionally subsequent heating, optionally in the presence of reducing agents (see the German Auslegeschriften 1068235, 1059429 and 1127882). Processes have also been described in which shaped bodies are made from catalytically active silver material be pressed without the aid of a carrier material (cf. German Auslegeschrift 1127 882). Finally, it is also possible by appropriate treatment of a silver-alkaline earth metal alloy to produce catalytically active silver surfaces suitable for the oxidation reaction. All of these mentioned Catalysts have the disadvantage that the effective surface, measured on the used Silver, is relatively small. On the other hand, it is known that size and Formation of the surface area of the catalyst are vital.

It has now been found that porous silver or copper catalysts for oxidation reactions, which are usually catalyzed by silver or copper, obtained when copper or silver salts, which are thermally decomposable below the combustion temperature of the carrier material used are, preferably from a -hydroxycarboxylic acid or silver or copper oxide to one below the decomposition temperature of the applied metal compound non-melting, due to combustion applies destructible carrier, then burns the carrier and possibly still present Metal oxide reduced in a known manner.

Preformed supports are preferably used. In those produced and used in accordance with the invention Catalysts can be both silver catalysts and copper catalysts Act. The process according to the invention is described below using the example of the production of silver catalysts described how they are used especially for the production of ethylene oxide by oxidation of Ethylene and oxygen or gases containing oxygen can be used. In a corresponding way you can but also copper catalysts are produced, processes for the production of porous silver and Copper catalysts

Applicant:

Petrochemistry

Company with limited liability,

5090 Leverkusen

Named as inventor:

Dr. Ludwig Bruns,

Dr. Günther Schnuchel, 4047 Dormagen

which can be used for other oxidation reactions.

The process for the preparation of the catalyst according to the invention is based on the fact that a framework made of finely divided material is initially used as a carrier of a silver compound and that this carrier material in the production of silver through thermal decomposition of the silver compound through oxidation gets destroyed. This creates a cavity system in the metallic silver, which in its expansion and characteristics corresponds to the carrier material previously used. It's on the Hand that by varying the original carrier material, the inner surface and structure of the invention Catalyst can be influenced within the broadest limits. The carrier material can e.g. Paper pulp or cotton pulp can be used. But it can also z. B. regenerated cellulose be used in the form of fibers or in the form of porous, spongy material. It It goes without saying that particularly impressive effects can be achieved by varying the denier of regenerated cellulose fibers can be achieved. Except cellulose and regenerated cellulose are suitable as temporary Carrier material all easily destructible by oxidation, below the decomposition temperature filamentary or porous materials which do not melt the silver compound used, e.g. Cellulose esters, polyacrylonitrile, polyamide fibers, other native celluloses and protein fibers, wood or so-called Activated carbons. In general, heating the is sufficient to destroy the temporary support material prepared with the silver compound in the presence of air. In the case of heavier decomposable ones Carrier materials, it may be appropriate to heat them in the presence of more oxygen-rich gases or even in pure oxygen.

809 539/420

3 4

For the preparation of the temporary carrier, repeated preparation of the silver skeleton obtained in the first preparation, especially the salts of organic α-hy- formation, with silver salt hydroxycarboxylic acids, in particular the silver salt of the melt or solution, and then repeated lactic acid. The salts of the -hydroxycarboxylic acids decompose can be achieved. This treatment causes a kind of soldering of the skeleton for the process described, so that it is well suited because when it is decomposed, the catalyst is preferably formed after the comparison of gases, which burn the silver body again with the carrier Able to drive up dilute metal and thereby treat the pore space with saline solution and help to enlarge it. The same effect can of course brought metal salt sets the metal free,
also achieved by adding propellants or io The production of the actual catalytically active strengthened, z. B. organic blowing agents such as silver, i.e. the decomposition of the silver salt and the foaming of rubber or the destruction of the temporary carrier, can be used in plastics, or easily decomposed in an oven, but can also borrowed carbonates, etc. Furthermore, mixtures of metal compounds 15 themselves can of course also be achieved by appropriate heating of the reaction vessel. The latter method is recommended to be used. Silver and copper catalysts are e.g. B. in linings as contained above z. For example, smaller amounts of other spellings were often written. The heat treatment, which is generally carried out, such as nickel, cobalt, manganese, iron or, if necessary, in the presence of oxygen, should contain barium, which is present in the usual amounts, e.g. B. up to 10% are carried out so that from the metal or higher, z. B. 50%, in the form of the lactate tensile compound, the metal is set free and can be mixed. The preferably produced that at the same time contain the greatest possible combustion silver catalysts also often contain the carrier used. It may be useful in the circumstances under gold, platinum or palladium as an admixture, e.g. B. when using specified amounts. of copper compounds that the decomposition is expediently carried out as a temporary carrier 25 of the copper lactate in two stages, namely selected fiber material with a melt of the organic silver salt, preferably a melt which is subsequently suitable for, because copper oxide can form primarily metallifrom lactic acid silver or α-hydroxyisobutter copper must be reduced. But it is also possible to use acid silver in a kneader to form a homogeneous one, the decomposition of the copper lactate processed with a mass. The deformation of this so obtained oxygen supply to undertake the complete combustion of the temporary carrier for the desired mass of the desired catalyst body can either take place in such a way that one is still sufficient.

not solidified mass with the help of suitable tools. B. tablet presses, which for the respective catalyst is a process that produces suitable moldings depending on the carrier used. For the 35 extraordinarily porous, yet mechanically still most of the process, it will be sufficient to create a sufficiently resistant structure from the mass. The high Pg with the help of a screw press an endless rosity - the porosity can for example 92% be formed into a strand of any cross-section and that - guarantees such a large flow after a drying process to the desired speed that the reaction gases produce a very effective piece size to break. It is of course also possible to achieve internal cooling. The microscopic picture made it possible to see from the mass plates of various thicknesses that a lifelike negative casting and after the solidification process cylinder pressure of the temporary support used was created or slices of any cross-section and any shape, comparable to the term »casting with lost thickness . The one in the process "Form" from bronze foundry technology,
Falling offcuts can be melted and reused. Thanks to its large surface, the invention can be used. Furthermore, the silver catalyst produced from the mass according to the previously used spheres of desired silver catalysts, which are produced with such a fine diameter and do not have a lining surface and do not change reaction vessels, can be carried out with the aid of a coating plate. are like flow through, in many cases superior, If it is necessary, such linings 50 so z. B. in the production of ethylene oxide and possibly also the formed cata- ethylene and oxygen or in the production of gates for the purpose of increasing the mechanical strength of propylene oxide from propylene and oxygen in counterpart with smaller proportions of foreign, non-disruptive silver catalyst. Other oxydadem and non-oxidizable material, e.g. B. glazing reactions, e.g. B. the oxidation of alcohol fibers, asbestos or wire mesh, are reinforced. In general, the proportion of such a proportion of oxygen in hydrocarbons, valuable materials in the catalyst is no more than approximately 10% with the unsupported silver catalyst. changes.

Another method of preparing shaped catalyst according to the described method 60 Example 1
Driving is based on the fact that pre-made moldings made of cellulose or other synthetic material are mixed in the form of 400 g of pure paper pulp in a kneader by dipping or spraying with the silver salt that is intimately used with 1200 g of molten silver lactate. In order to solidify the resulting pulp to melt or the aqueous solution is prepared. Avoid 65, the mass must throughout the ProWenn to the catalyst to be prepared zesses special at a temperature of about 60 ⁰ C held DERS high demands with respect to the mechanical be. The finished mixture is now placed in a niche stability, so this can be transferred through a screw press and into a strand

about 5 mm in diameter. It is then allowed to cool and the strand is broken into even pieces about 10 mm long. The pieces are placed on a glass-lined drying tray in a decomposition furnace, and at 300 ^c C decomposed over 30 minutes. An extremely porous, silver-gray material is obtained.

A tube with an internal width of 20 mm and a length of 1 m is filled with this catalyst. The pipe will heated to 235 ° C. Through the pipe, 2001 / hour. a gas mixture of the following composition:

4.15% ethylene,

6.06% carbonic acid,

6.00% oxygen,

Remainder nitrogen.

An analysis of the gas emerging from the pipe shows the following composition:

ao

2.78% ethylene,
7.50% carbonic acid,
2.63% oxygen,
0.98% ethylene oxide,
Remainder nitrogen.

The analytical data show that there is a 72% yield based on the amount of ethylene converted (= 32% of the input amount per pas), ethylene oxide has formed.

Example 2

a) 251 of a cellulose wadding molded body with the dimensions 6 mm in diameter and 10 mm in length are introduced into a 50 ° C melt of silver lactate and left in it until the pulp has soaked up with the lactate melt. The shaped bodies are then left on a sieve drain. It is allowed to cool and the shaped bodies are placed in smaller batches on flat stainless steel sheets distributed in an oven to decompose. The decomposition is expediently carried out in such a way that that you first quickly heated to 300 ° C and this temperature over the period of one Maintains hour. In this way, moldings made of pure silver are obtained, the bulk density of which depends on The density of the pulp body used is between 0.5 and 1.5.

b) The catalyst can be varied by adding, for example, 10% of another to the silver lactate Metal lactate added, e.g. B. the lactates of nickel, cobalt, chromium, manganese, iron, gold, platinum, Palladium and barium.

c) The catalyst obtained according to Example 2, a) or 2, b) is used to fill a tube with an internal width of 20 mm and a length of 1 m. The tube is heated to 22O ⁰ C. Through the pipe, 2001 / hour. a gas mixture of the following composition:

Example 3

a) 5 kg of cylindrical cellulose wadding pieces measuring 9 × 9 mm are sorted on a chain belt and continuously pulled through a solution of silver lactate which contains 40 to 43% silver. The residence time at 80 ° C is 5 minutes. After this impregnation, the moldings are transferred to another chain belt and exposed to a temperature dropping from 210 to 175 ° C for 30 minutes in a continuous process. The decomposition gases are sucked off. The cellulose is still preserved in the formations that have been moved forward in this way. They are now also briefly heated to 270 to 300 ° C in a continuous process, leaving the cellulose completely glows, leaving behind a silver skeleton with 92% pore space, an apparent density of 0.9 to 1.3 and a compressive strength of 10 kg / cm ² . The yield of the finished catalyst is about 30 kg.

12 kg of the catalyst obtained in this way are in a semi-industrial tubular reactor, consisting of ten tubes made of chrome steel with a clear diameter of 21 mm and a length of 6000 mm, filled in such a way that 1.2 kg of catalyst are evenly piled up per tube and the flow resistance is 0.3 atm over the entire reactor.

The diphyl bath surrounding the tubes is heated to 249 ° C. and kept at this temperature by a thermostatic system. The reactor is then 200 Nm ³ / hour. a gas mixture of the following composition:

5.28% ethylene,
6.56% carbon dioxide,
6.80 «/» oxygen,
0.04% ethylene oxide,
Remainder nitrogen.

The pressure is 14.5 ata.

The following volume proportions are measured in the gas mixture leaving the reactor:

3.38% ethylene,
7.47% carbon dioxide,
4.57% oxygen,
1.37% ethylene oxide,
Remainder nitrogen.

So there are 246 g of ethylene oxide per liter of reaction space and hour. Per passage were 1.9% ethylene converted, which corresponds to a conversion of 36%, based on the ethylene input concentration of 5.28 ° / o. The selectivity is calculated according to the formula

Δ -ethylene -

/ (- carbon dioxide

Δ -ethylene

4.5% propylene,
6.0% oxygen,
89.5% nitrogen.

to 76%. After several months of operation, there was no waste the yield observed.

"BJ For comparison, a state-of-the-art Like an analysis of the corresponding silver-coated aluminum gas mixture emerging from the pipe it contains 0.03% propylene oxide. Carbon dioxide is the only by-product formed

been.

Oxide supported catalyst, as it is after the German Auslegeschrift 1 059 429, Example 1, is obtained, charged into the above reactor. The filling

7 8

per tube is 3.2 kg and the flow impedance mass, which when filling into the reactor is partially

was 0.5 atm over the entire reactor. When one crumbles to powder. With caution, 120 g

Reaction temperature of 247 ° C, the reactor is catalyst in a 1 m long and 21 mm wide tube

be filled with the same amount of gas and the same gas. Afterwards, at a temperature

composition at the same pressure as above, temperature of 250 ° C and normal pressure per hour 2001-

beats. Gas of the following composition introduced:

In the gas mixture leaving the reactor

the following volume proportions are measured: 4.40% ethylene,

5.00% oxygen,

4.17% ethylene, ₁₀ balance nitrogen. 7.22% carbon dioxide,

5.53% oxygen. The gas exiting the reactor was as follows

0.82% ethylene oxide, composition: balance nitrogen.

15 4.12% ethylene,

So 0.16% carbon dioxide is generated per liter of reaction space and hour,

160.5 g of ethylene oxide obtained. 4.56% oxygen is used per passage,

1.1% ethylene converted, which corresponds to an um- 0.20% ethylene oxide,

rate of 21%, based on the ethylene inlet con - remainder nitrogen,

centering of 5.28%. The selectivity is calculated 20

to 70%. After 6 months of operation, the weight per liter of reaction space and hour is 2.3 g yield of ethylene oxide per reaction chamber and ethylene oxide. 0.28% per passage Hour still 144 g. Ethylene implemented, which corresponds to a conversion of

c) For further comparison, a pure silver 6.3%, based on the ethylene inlet concentration catalyst, the prior art corresponding to 25 tion of 4.4%. The selectivity is 71.5%. To and produced according to the German interpretation 2-hour operation could be in the reaction gases. 1127 882, example 4, in the form of cylindrical no ethylene oxide, but only carbon dioxide 4X9 mm pills are detected in the above as oxidation products, th reactor filled. The filling weight per tube is e) In the same tube as in Example 3, d) of

4.95 kg and the flow resistance over the 30 mm length and 21 mm width of the reactor according to the invention is 0.6 atm. Corresponding carrier-free, pure silver, shaped skeleton cat- The reactor is filled into the analyzer according to Example 3, a) at a temperature of 248 ° C. The filling and a pressure of 14.5 ata / hour. with 200 Nm ³ weight is 228 g of catalyst. A gas with the following gas composition is applied at a temperature of 250 ° C and normal pressure per hour: 35 2001 of a gas with the following composition is 5.14% ethylene, passed:
6.82% carbon dioxide, 5.10% ethylene, 6.70% oxygen, 6.15% oxygen, 0.03% ethylene oxide, the remainder nitrogen. Remainder nitrogen. 40

The gas leaving the reactor contains The gas leaving the reactor showed the following
Composition: 2.22% ethylene,

2.85% oxygen,

3.50% ethylene, ₄₅ 1.60% carbon dioxide,

7.90% carbon dioxide, 2.15% ethylene oxide,

4.08% oxygen, the _remainder nitrogen.

1.13% ethylene oxide,

Remainder nitrogen. p _r0 Lher reaction space and hour are 24.4 g

50 ethylene oxide obtained. 2.88% per passage

That is converted per liter of reaction space and hour of ethylene, which corresponds to a conversion of 228 g ethylene oxide. Per passage 1.64% is 56.5%, based on the ethylene inlet concentration ethylene implemented, that is 32%, based on the tion of 5.1%. The selectivity is 74.6%. To Ethylene inlet concentration of 5.14%. The 200 hour operation will not change the selectivity is 67%, 55 data observed after 8 hours of operation, the selectivity quickly falls below 60%. The more incidental Heat of reaction is no longer absorbed by the bath Example 4, so that the total combustion of the

Ethylene to carbon dioxide comes to the fore. 64.5 g of cylindrical cellulose wadding moldings of the

The flow resistance increases to 1 atm. The 60 dimension 10 X 10 mm are made with an aqueous The amount of gas passing through the reactor is 150 Nm? Copper lactate solution containing 17.2% copper return. The removed catalyst is saturated with soot above -60 ° C. The drinking time is about 2 mitzog and melted into larger lumps. After the soaked bricks have cooled down, mill them. which this initially held at 175 ° C for IV2 hours

d) For a third comparison, a pure silver 65 and then the temperature is increased to 220 ° C British patent catalyst for cellulose leaving behind a copper-434 011 produced by decomposing silver oxalate. Copper oxide skeleton completely glows. The Aus-That obtained silver is a voluminous loose prey is 300 ml with a weight of 160 g.

65 g of the catalyst obtained in this way are placed in a quartz tube 500 mm long and 20 mm thick Width filled in. The reaction space is electrically brought to a temperature of 400 ° C and a Mixture of 168 g of methanol and 163 g of water by evaporation over the catalyst in one hour directed. For this purpose, 1201 air are given per hour. After passing through the reaction tube, a liquid fraction of 245 g collected, the 9.8 percent by weight formaldehyde, 15.8 percent by weight Contains methanol and the remainder water. This corresponds to a conversion of 77% with a selectivity of 20 ° / o. The removed catalyst consists of pure copper.

Example 5

40 g of molded cellulose pieces measuring 10 × 10 mm are soaked in a solution of 20 g of Cu (NO ₃ ) ₂ · 3 H ₂ O in 10 g of water at 50 ° C. for 3 minutes. The cellulose prepared in this way is dried in vacuo at 80 ° C. for 4 hours.

The dried moldings are heated to around 200 ° C. The cellulose glows under A molded copper-copper oxide skeleton is left behind. Remnants of cellulose or its decomposition products are no longer detectable in the formations.

For conversion to pure copper, the moldings are treated in an electrically heatable tube at about 300 ⁰ C with methanol vapor. Highly porous moldings made of pure copper metal are obtained in the same dimensions as the cellulose moldings used. As described in Example 4, this catalyst is suitable for the oxidation of alcohols to aldehydes.

Example 6

120 g of moist silver oxide with about 30% water content and 10 g of fine-fiber paper pulp are used mixed into a uniform pulp. For shaping, the pulp is fine-tuned using an extrusion press Shaped strands.

These strands are, after drying in vacuo at 8O ⁰ C broken on desired piece size and then heated to 200 to 250 ° C.

The cellulose burns without leaving a residue, leaving behind a porous, shaped, pure silver Catalyst, which is excellent, as described in Example 1, for the oxidation of olefins suitable for olefin oxides.

Claims (4)

Patent claims: 1. Process for the production of porous silver and copper catalysts for oxidation reactions, usually by silver or Copper are catalyzed, characterized that one copper or silver salts which are thermally decomposable below the combustion temperature of the carrier material used are, preferably from a «-hydroxycarboxylic acid or silver or copper oxide, to one below the decomposition temperature of the metal compound used, non-melting, applies destructible carrier by incineration, then burns the carrier and any metal oxide still present is reduced in a known manner. 2. The method according to claim 1, characterized in that preformed carriers are used. 3. The method according to claim 1 and 2, characterized in that as «-hydroxycarboxylic acid Lactic acid used. 4. The method according to claim 1 to 3, characterized in that the catalyst is after the incineration of the carrier treated again with dilute metal salt solution and from the additional applied metal salt sets the metal free. Considered publications:
German Auslegeschrift No. 1 068 235,
093 344, 1124 030, 1127 882;
British Patent No. 434 011. 809 539/420 4.68 © Bundesdruckerei Berlin