DE1122929B - Process for the production of catalysts in a fluidized bed - Google Patents

Description

Process for the production of catalysts in the fluidized bed Production of supported catalysts, e.g. B. containing vanadium and potassium sulfate Supported catalysts, until now, silica gel, which after an entangled, the addition obtained from sulfuric acid to a potassium silicate solution in a closing process is converted into a paste with a soluble vanadium compound, which is subsequently is dried and heated. The catalysts produced in this way have the considerable Disadvantage that they are not mechanically stable and quickly disintegrate when they are in find a fluidized bed reactor use. The one in the room above the bed Catalyst dust formed can lead to an undesirable increase in temperature. Filters are usually provided to prevent leakage of catalyst particles impede. If the temperature rises above the bed it can affect the filters create hot spots and damage the filters.

In the manufacture of catalysts for the cracking of oils through Treatment of alumina with acids is known to volatilize the acids in it Condition on the finely divided alumina after the fluidized bed process to take effect. The use of the fluidized bed process is also known to evenly distribute a substance that is normally liquid or light is to be liquefied, on finely divided solid materials, such. B. in manufacture of cleaning agents and detergents made from heat-sensitive surface-active substances Substances whose properties are improved by adding other suitable substances should be.

The invention relates to a process for the production of catalysts in the fluidized bed, which is characterized in that particles of a catalytic Substance in a fluidized bed of porous carrier particles at a temperature at which the catalytic substance melts, entered and the fluidized bed up to the inclusion of the catalytic material is maintained by the carrier particles.

The solid particles of the catalytic substance must be at the temperature of the bed become liquid and wet the porous particles, so that the resulting Liquid is absorbed or adsorbed by the porous carrier particles. Of the catalytic material must be completely absorbed by the carrier particles. The fabric but should not form a coherent thick layer on the surface of the particles, because then the mass of the particles would bake together if they were used as a catalyst to be used.

The carrier particles can expediently consist of silica gel, but also, for. B. activated alumina, pumice stone, zeolites, clays or metallic oxides provided that they are porous and stable at the working temperature. But not every silica gel is suitable as a carrier in every catalytic reaction. An empirical attempt is that the silica gel or other carrier particles be mixed in the desired ratio with the catalytic substance and the mixture in a muffle furnace to a temperature above the melting point of the catalytic The substance is heated with stirring. Suitable carrier particles result after a few hours a dry, mobile powder, while unsuitable carrier particles result in a sticky, lead agglomerated mass.

The degree of porosity of the carrier particles can vary greatly. Not at all but these particles are allowed at the temperatures at which the catalyst Should be used, sintered together.

It was found that the amount of the carrier particles after the catalytic substance absorbed over a certain period of time is the greater, ever The grain size of the individual particles of the carrier is smaller, since the smaller particles first be fully impregnated. This is beneficial because the smaller particles become heavier and therefore less easily blown out of the fluidized bed can. Typical particle sizes are in the range from 75 to 300po.

The process according to the invention can be used for the production of catalysts which are used in a wide variety of reactions. It is special applicable to catalysts containing vanadium and potassium sulfate used in the manufacture of phthalic anhydride can be used.

A mixture consisting of vanadium pentoxide and potassium pyrosulphate results when melting a glass that can be ground into fine particles and not any has a sharp melting point. The softening point of such a mixture depends on the molar ratio of potassium pyrosulphate to vanadium pentoxide. This is shown in Fig. 1 of the drawing explained. The molar ratio is logarithmic on the abscissa K2O: V2O5 drawn in, while the softening point of the resulting glass is entered on the ordinate. As can be seen from the diagram, there is the softening point at a minimum when the molar ratio is approximately 8.5. The molar ratio in the catalyst is important in determining its reactivity and is preferably in the range from 1.0 to 6.0. Is within this range the softening point below 320 C. Therefore, if the temperature in the fluidized bed is between 350 and 400; C, the glass will quickly form a liquid over the surfaces of the carrier particles distributed. The final activation of the catalyst should be at a Temperature of 400 to 42G ° C can be carried out.

The heat of wetting and the pore size can also be used to determine the suitability of porous particles to be used as supports for catalysts found in the production of phthalic anhydride use. For example result two commercially available silica gels show the curves according to FIG. 2.

When they are wetted with tributyl citrate, the heat of wetting is in cal / g is entered as the ordinate and the time in minutes as the abscissa. The curve 1 tends to have a high heat of wetting for the first silica gel, from which it can be seen that it has a large internal surface. Curve II shows a low, extending over a wetting heat extending over a longer period of time, from which it follows that the silica gel II has a smaller pore diameter than the first. These two gels have high internal specific surface areas as measured by nitrogen absorption (500 m2 / g for the first and 710 m2lg for the second). The pore diameter of the first Gels (53 Å), however, is much larger than that of the second gel (14A).

The first gel is suitable for a catalyst that is used in manufacture phthalic anhydride can be used, but the second cannot. In general it can be said that for this purpose a high heat of wetting and a pore size of at least 40 A are required.

The ratio of the catalytic material to the carrier particles can vary within wide limits.

For example, when using silica gel and a glass from vanadium and potassium sulfate that Glass 1.0 to 35.0 percent by weight of the catalyst be. Very satisfactory results will be obtained with 25 percent by weight of one Glass with a molar ratio of K2O: V2Os = 4: 1.

This results in a lower V2Os concentration in the finished catalyst (approximately 4%) compared to 9 to 10% in those produced by the previous processes Catalysts. But because the catalyst is just as effective as the previous catalysts there is a vanadium saving. In addition, the manufactured according to the invention Catalyst doesn't break down as quickly.

When carrying out the method according to the invention, a part of the carrier particles with the catalytic substance in a vortex blade of the remaining Carrier particles are introduced.

Fig. 3 shows schematically an example embodiment of a Device for carrying out the method according to the invention and is used during manufacture a catalyst that is used in the production of phthalic anhydride, explained. First is a mixture of vanadium pentoxide and potassium pyrosulfate melted, poured, ground to approximately 150au. weighed and placed in a drum mill with some silica gel particles having a pore size of 40 to 60 Å and a particle size mixed between 75 and 300k. This mixture is poured into a filled funnel 1 abandoned, as which they - regulated by eln valve 2 - via a line 3 enters the swirl chamber 4. Compressed air supplied through a line 5 flows through a preheater 6 with external electrical heating and a line 7 with a control valve 8 to the bottom of the column 4, where it exits through a distributor ring 9. This air then flows in column 4 upwards. around the particles located therein in a liquid-like manner To keep state.

By means of external heating elements 10, a temperature between Maintain 350 and 400 C. Filters are located at the top of the column 11, through which the air flows to from here via lines 12 and 13 into a Fireplace to arrive.

At the bottom of the column there is one regulated by a valve 15 Outlet 14, which is opened upon completion of the preparation of the catalyst, during the air flow is maintained. so that the catalyst is whirled up Form is emptied to od in barrels. Like. To be collected.

To facilitate the passage of material from the hopper 1 into the column 4, the particles in the funnel are whirled up from time to time.

The air used for this can be that flowing upwards in the column Air can be extracted. This air leaves the funnel via a line 16 and passes from here into the filter 11, so that the attachment of a special filter device superfluous on the funnel.

The main current coming from line 5 can be bypassed of the heater 6 reach the column 4 via a line 17 with a control valve 18. Therefore, cold air can be blown through the column after it has been emptied Remove dust residues.

For example, the height of a column 4 was 7.0 m and its diameter 4.27 m; 215 kg of silica gel were whirled up in it by air at 350 to 400 "C; the The air speed in the empty column was 0.15 m / sec. 72 kg of the powdered Vanadium pentoxide potassium pyrosulphate glass mixed with 48.6 kg of silica gel, were added over a period of 3 hours.

The fluidized bed was maintained for a total of 8 hours, the temperature increased to approximately 420 ° C. during the last two hours was used to activate the catalyst.

At approximately 600 "C, the pore structure of the silica gel tends to shrink and coincidence; the temperature in the column must therefore be well below this Value and advantageously below 500 ° C. when the carrier particles consist of silica gel.

Below are examples of the absorption of some of these substances by Silica gel reproduced.

Example 1 This example illustrates the preparation of potassium dichromate catalysts for aromatization reactions. One of 150 parts by weight of K2Cr207 and 150 parts by weight of large-pored silica (i.e., with pores approximately 45 Å in size) became slow run into a column heated to 430 C and 200 parts by weight of the same Contained aerated gel. Over the course of 3 hours the was potassium dichromate absorbed by the silica gel.

Example r This example illustrates the preparation of chromium catalysts for cyclic and aromatization reactions. A mixture of 150 parts by weight Cr03 and 150 parts by weight of large-pore silica gel was slowly poured into a column let in. which was heated to 200 C and 200 parts by weight of the same. by Contained air swirled silica gel. Over the course of 3 hours, the CrO3 absorbed by the gel. When the temperature was increased to 300 C, the CrO3 converted to Cr2OA.

Example 3 This example explains the production of copper chlorine Catalysts for oxidation and polymerization reactions. One of 80 parts by weight The mixture consisting of large-pored silica gel and 20 parts by weight of Cu.Cl2 became slow allowed to run into a column. which was heated to 4356C and 100 parts by weight of c of the same air-dispersed silica gel. The copper chlorine was absorbed by the gel in approximately 3 hours. Example 4 This example illustrates the production of nickel catalysts for hydrogenation reactions. It is also a Example of a gel that is impregnated with a catalytic substance. which melts and decomposes. One column. the 132 parts by weight of large pores, whirled up by air Contained silica gel. was heated to 60 ° C. 87 parts by weight of nickel nitrate Ni (NO3) 6 H.O., which were mixed with 200 parts by weight of Ki dcl, slowed the column admitted. The color of the gel became uniform, ißg gi ün. The addition wqr in 30 minutes completed. The temperature was slowly raised to 350 ° C over approximately 3 hours elevated. The color of the bed turned pale green. Developed at 150 C. nitrogen oxides, and the impregnated gel became progressively darker until the final catalyst, d. H. the silica gel with absorbed nickel oxide was black. Example 5 I example 5 This example illustrates the preparation of a catalyst for hydrogenation and desulfurization processes. 125 parts by weight of large-pored silica gel, which is between 0.1 and 0.3 mm sieves sized were introduced into a column at 900.degree and blown up with air. One made from 123.7 parts by weight of finely powdered cobalt nitrate Co (NO3) 2 6 H20 and 100 parts by weight of the same silica gel mixture slowly given up in the column. The temperature then gradually rose to 1800 C increased and held at this level until the nitrate was decomposed. In the The lower temperature melted the cobalt nitrate hydrate and was instantly in the silica gel absorbed. When the temperature increased, it became water first and then nitrogen oxide expelled, leaving a gel coated with 13.60 / 0 cobalt oxide, Cm203 was. The operation was completed in 2.5 hours.

Example 6 This example illustrates the preparation of a silver catalyst for the oxidation of ethylene to ethylene oxide. In a column were at 2200 C 185 parts by weight of large-pored silica gel classified between 0.1 and 0.3 mm sieves introduced and fluidized with air. 23.6 parts by weight of finely divided silver nitrate. mixed with 100 parts by weight of the same silica gel became slow added. The temperature of the fluidized bed was then increased to 460.degree. The silver nitrate decomposed, leaving a silica gel with metallic silver (50! 0) was covered. The work process took approximately 3 hours.

Usually there is only a single catalytic material on the porous Bearer dejected; but if a mixture of catalysts is required, can easily take up two catalytic substances from porous supports will.

For example, cobalt nitrate hexahydrate and nickel nitrate hexahydrate can be used at the same time Find use. Example 7 Example 7 200 parts by weight of crushed activated carbon, which was classified to a grain size between 0.7 and 0.07 mm, were in a column whirled up at 600 C by nitrogen. A mixture that consists of 35.7 parts by weight of finely divided tin chloride (SnCl2 2 H2O) and 70 parts by weight of the same activated carbon passed was slowly added. The temperature then gradually rose to 2600 C increased. The entire process took approximately 3 hours. The catalyst passed made of 90 ° '"carbon, which was coated with 10ovo SnC12. Such a catalyst is used in organic condensation reactions.

Example 8 250 parts by weight of pumice stone, which is 0.152 mm thick were vortexed with air in a column at 390 ° C. In the column a mixture was slowly added over a period of 3 hours, the 200 parts by weight of the same crushed pumice stone and 25 parts by weight the powdered, already mentioned melt of vanadium pentoxide-potassium pyrosulphate duration.

The resulting catalyst contained 5% melt.

PERSONAL CLAIMS: 1. Process for the production of catalysts in Fluidized bed, characterized in that particles of a catalytic substance in a fluidized bed of porous support particles at a temperature at which the catalytic substance melts, entered and the fluidized bed up to inclusion of the catalytic material is maintained by the carrier particles.

Claims (1)

2. The method according to claim 1, characterized in that a mixture from porous Carrier particles and the catalytic material in a fluidized bed of carrier particles is entered. 3. The method according to claim 1, characterized in that the catalytically active substances added to the carriers in amounts of 1.0 to 35 percent by weight will. 4. The method according to claim 1, characterized in that the temperature of the fluidized bed is kept between 90 and 460 ° C. 5. The method according to claim 1, characterized in that the catalyst is activated by temperature treatment in a fluidized bed. Documents considered: German Patent No. 845 794; German Auslegeschrift N 7249 IVa / l2 g (published on May 30, 1956).