DE1642921C3 - Supported catalyst containing vanadium and titanium - Google Patents

Description

30th

The main patent relates to a supported catalyst containing vanadium and titanium, obtained by application a mixture of finely divided titanium dioxide and the solution of a vanadium compound an inert, non-porous support in such a way that the support after drying in a layer thickness of 0.02 to 2 mm is coated with the active material, which is 1 to 15 percent by weight of vanadium pentoxide and 85 contains up to 99 percent by weight of titanium dioxide, and the finished supported catalyst contains vanadium pentoxide from 0.05 to 3 percent by weight.

The subject of the 1st additional patent is a supported catalyst according to the main patent, which is identified by a carrier, which is applied before the mixture of finely divided titanium dioxide and the Solution of the vanadium compound with an oxide of the metals vanadium, molybdenum, tungsten, chromium, titanium and / or iron has been primed.

It has now been found that a supported catalyst according to the main patent and optionally according to the 1st additional patent has an increased coating strength when the application of the mixture of finely divided Titanium dioxide and the solution of the vanadium compound to a temperature of 160 to 500 C, in particular 270 to 500 C, heated carrier takes place.

The new catalyst has a high coating strength. While so far in many cases during transport and when it was poured into the oxidation reactor, parts of the coating crumbled off and thus an ω If particularly careful handling was required, the new catalyst shows only minimal abrasion. Crumbling of the coating is no longer observed. Regarding the usability of the catalyst, the suitable catalyst support, if necessary b5 the primer or pretreatment of the support, the Catalyst coating composition and carrying out the oxidation reactions using the The new catalytic converter does not differ from the catalytic converter of the main and 1st additional patent.

The coating is carried out in such a way that the optionally primed carrier is at a temperature between 160 and 500 C, preferably 270 to 500 C, in particular 280 to 450 C, is heated. One works well in a heated coating drum, a rotary kiln or on a vibrating surface.

The mass used as a catalyst coating, which in the dry state contains 1 to 15% by weight of vanadium pentoxide and should contain 85 to 99 wt .-% titanium dioxide, is in dissolved or suspended form applied to the carrier. The solvent or suspension medium used is water or an organic solvent, such as formamide or alcohol. Titanium dioxide is generally in suspension Form, vanadium pentoxide or a vanadium compound that converts to vanadium pentoxide when heated is, generally in dissolved form. Generally one works with a porridge, the honey-like one Has consistency. With the new coating method, the water or the solvent evaporates practically instantaneously as soon as the mass comes into contact with the carrier.

The finished catalyst should be 0.05 to 3, preferably 0.1 to 2, in particular 0.05 to 1% by weight of vanadium pentoxide contain.

In addition to vanadium and titanium, the catalyst mass can also contain small amounts, for example 0.1 to 5% by weight, to compounds of other elements such as copper, silver, lithium, niobium, arsenic, antimony, phosphorus, chromium, Contains molybdenum, tungsten, manganese, iron, nickel, cobalt and aluminum.

Compared to the catalysts described in US Pat. No. 3,177,229, in which the Carrier receives an aluminum oxide primer before coating with vanadium pentoxide, and to the from GB-Patent 6 69 999 known catalysts, during the production of tin oxide during or is added after the coating of the carrier with the vanadium compound is obtained with the inventive Catalysts in the oxidation of o-xylene to phthalic anhydride give considerably better yields.

example 1

790 g of vanadyl oxalate are dissolved in 1670 g of formamide and 10650 g of water and then finely divided with 5900 g Anatase mixed. 75 kg of steatite balls with a diameter of 6 mm are placed in a coating drum heated to 350 C. With a spray device, the hot balls with the above mixture sprayed. The drum is heated from the outside so that no temperature drop occurs when spraying. All the liquid is evaporated at the moment of contact with the hot ball. The balls have an active mass of 6.14%. The finished catalyst contains 0.48% vanadium pentoxide.

Lets 100 g of this catalyst through a 3 m long upright tube with a diameter of 0.25 m fall, the catalyst loses only 0.25% of the active mass.

If, on the other hand, the balls are coated with the active material at room temperature in the coating drum and then dried at 200 ° C., the drop test shows a loss of active material due to crumbling of 12%.

Of course, instead of titanium dioxide

a solution of a titanium compound can also be used, which converts to titanium dioxide when heated will, e.g. B. alcoholic solutions of titanium alcoholates or titanium tetrachloride.

The different coating strength of catalysts coated at different temperatures can be seen from the following table:

Temperature of the sphere during Loss of active mass of spraying in the drop test 170 C 8.4% 220 C 5.8% 250C 5.2% 270 C 1.5% 315 C 0.34% 350 C 0.25%

At 410 ° C., 41 g of 98% strength o-xylene with 11001 air are passed over 400 g of the catalyst coated at 350 ° C. every hour. The weight yield of phthalic anhydride is 102% in the first 6 hours, after 7 days the catalyst has its constant activity. The weight yield is then 114.8%.

Example 2

75 kg of steatite balls with a diameter of 6 mm are placed in a heated coating drum 300 C and heated with a solution of 1.2 kg of vanadium oxalate in 1 kg of formamide, 2 kg of water and 1 kg of urea sprayed. Then the balls are muffled at ίο 400 C for 30 minutes. Located on the balls a layer of 0.6% by weight vanadium pentoxide. Then the balls are in the heated coating drum heated to 350.degree. C. and sprayed with the aqueous suspension indicated in Example 1. The active one The mass is absorbed by the balls in an amount of 6.14%. The finished catalyst contains a total of 1% by weight vanadium pen oxide.

The catalyst produced in this way is filled into 3 m long tubes with a salt melt heated to 390.degree are surrounded. 50,000 liters of air and 200 g of o-xylene are passed through each tube every hour.

In continuous operation of about 2 years, a yield of 112% by weight of phthalic anhydride is obtained.

Claims (1)

Claim: Vanadium- and clay-containing supported catalyst, obtained by applying a mixture of finely divided titanium dioxide and the solution of a vanadium compound on an inert, non-porous Carrier in such a way that the carrier after drying in a layer thickness of 0.02 to 2 mm with the active mass is coated, which is 1 to 15 percent by weight Contains vanadium pentoxide and 85 to 99 percent by weight titanium dioxide, and the finished supported catalyst has a vanadium pentoxide content of 0.05 to 3 percent by weight, according to the patent 14 42 590, where appropriate the carrier, before applying the mixture of finely divided Titanium dioxide and a solution of a vanadium compound with an oxide of the metals vanadium, Molybdenum, tungsten, chromium, titanium and / or iron has been primed, according to patent 1542023, characterized in that the application of the mixture of finely divided titanium dioxide and the solution of a vanadium compound to a temperature of 160 to 500'C, in particular 270 to 500 C, heated carrier has taken place.