SU628943A1 - Method of preparing catalyst for oxidizing o-xylene into phtalic anhydride - Google Patents

Claims (3)

The invention relates to methods for the preparation of catalysts for the oxidation of aromatic hydrocarbons, E in particular for the oxidation of o-xylene to phthalic anhydride. A known method for the preparation of a catalyst for the oxidation of o-xylene to phthalic anhydride, consists in the fact that at first an aqueous suspension of vanadium pentoxide at elevated temperature (8 0 95 C) is processed to an alkaline acid. The resulting solution of vanadyl oxalate is extruded8 and then dissolved at 8–120 ° C in a solvent (formamide, urea, etc.). Titanium dioxide is added to the resulting solution, and the mixture, after agitated agitation, is applied on an inert carrier. The catalyst is then dried and calcined at 45O-5OOC. Lj. There is also known a method for producing a vanadium-titanium catalyst by treating ammonium vanadate or vanadium pentoxide at elevated temperature with an ammonia solution, followed by mixing with titanium dioxide and applying the resulting mixture on an inert carrier. Closest to the proposed invention is a method for the preparation of a vanadium titanium catalyst for the oxidation of o-xylene to phthalic anhydride by treating an inert carrier, for example, silica gel or porcelain, with a mixture prepared from pentoxide, oxalic acid, formamide, titanium dioxide at 20O-ZOO C. n monosubstituted ammonium phosphate, followed by calcination at 45 ° C in a stream of air for - 1 hour 3j. The preparation of catalysts by a known method requires the preliminary preparation of solutions of vanadium compounds, specific treatment methods and special solvents. These requirements complicate the process and instrumentation of catalyst production. The purpose of the invention is to simplify the process of preparing catalyst. For this purpose, an aqueous solution of vanadophosphate of the following composition (NH4lTi: PlV6W) is used as vanadium and phosphorus compounds. The proposed method makes it possible to exclude the use of oxalic acid, phosphoric acid (ammonia water, ammonia water), to simplify the process |: , such as obtaining vanadium oxalate, dissolving it in formamide, etc. The catalyst is prepared as follows: The vanadophosphate salt is dissolved in distilled water at 20-5 ° C, then guitar dioxide is added and mixed after stirring. The mixture is applied to a non-porous inert carrier (phosphorus, quartz, corundum, etc.) at 2OO300 0. The resulting catalyst, the active mass of which contains 2, O-3.0 mol% YjO, 0.2-0.3 mol.% 2 ° 5 and 98 mol.% ri 02 are loaded into a contact tube immersed in a salt heated bath.When passing through a xylene-air mixture with an o-xylene content of 0.6-O, 9% by volume, the space velocity is 35OO-5OOO hour and the temperature requirement is 370-400 o, the output of phthalic aluminum oxide is 73-75 mol. % in terms of 100% o-xylene. Example. In zoo ml distilled water. 3.7 g of vanadophosphate of the composition (((,, adding south 60 g of finely dispersed titanium dioxide and dissolve thoroughly. dissolve the mixture slowly (at least 2 hours put on O, 8 l of | 6-6 mm diaphragm) in the temperature range 200-300 ° C. with constant stirring, a catalyst is obtained containing 0.24% by weight of Y205.O, O2% by weight V2Qs 4.6% by weight and 95.14% by weight of carrier The catalyst is loaded into a tube with Internal diameter of 2 O-25 mm, immersed in a heated salt bath. Through the tube, at the temperature of the salt bath, 140 g of 98% o-xylene and 3500 are passed every hour L of air. 144 g of phthalic and 9-10 g of maleic anhydrides are obtained. The yield of phthalic anhydride is 75 mol.% based on 100% o-xylene. Example 2. In 360 N.71 of distilled water is dissolved 6.1 g ammonium vanadophosphate, add 85 g of finely dispersed titanium dioxide and mix thoroughly.The resulting mixture is applied in a uniform layer on the surface of 1 l of quartz (fraction 5-7 mm) in the temperature range 230-29 ° C. When passing through a catalyst containing 0.25 weight . % VgOj, 0.02 wt. , 4.33 wt.% IOa and 95.4 wt. % of carrier xylene-air mixture with the concentration of o-xylene 0,7-0,8 about. %, a flow rate of 50OO hours and a bath temperature of 380 ° C, the output of phthalic anhydride is 74 mol. % in terms of 1OO% o-xylene. The invention method of preparation of the catalyst for the oxidation of o-xylene to ft; aleic anhydride- mixture of compounds of vanadium and phosphorus with titanium dioxide, followed by applying the mixture on an inert carrier at 200-ZOO C, in order , as compounds of vanadium and phosphorus they use water solution, vanadophosphate of composition (NH) (G20y) b1. Sources of information taken into account during the examination: 1. French patent No. 1480078, cl. C O7 C, 1968. 2. Author's svdekdedelstvo USSR № 415О39, cl. O1 J 37/02, 1972. 3. The patent of France No. 2О1596О, cl. At 01 J 11/00, 1970.