The method of preparation nickelchromium catalyst for the hydrogenation of benzene

 

(57) Abstract:

Use: in the manufacture of catalysts and may find application in the production of nickelchromium catalysts for the hydrogenation of benzene. The invention is: to improve the activity and stability of catalyst for the hydrogenation of benzene, the process is carried out by precipitation of the active nickelchromium composition from a solution containing Nickel nitrate and chromium compound, in the presence of the precipitator, dehydration, drying and calcining the resulting mass with the subsequent formation of the catalyst, and as compounds of chromium using chromic anhydride, and as precipitator - urea. The last charge in the amount of 30 to 60 wt. % from stoichiometric to the amount of Nickel and chromium. The dehydration is carried out by parki and operation of parki, drying and calcining combine. 2 C. p. F.-ly, 1 table.

The invention relates to the production of catalysts, in particular nickelchromium catalysts for the hydrogenation of benzene.

There is a method of cooking nickelchromium catalyst for the hydrogenation of benzene, comprising the mixing of solutions of Nickel nitrate and ammonium bichromate, dried, ignited the value of the mixture solution is heated nozzle of inert material inert gas in the fluidized bed mode at 310-340about[1]

The disadvantage of this method is the complexity of the process of drying and calcination in flowing furnace in "boiling" layer of the nozzle, the complexity of the cleanup circulating in the inert gas from the gaseous products of decomposition of Nickel nitrate and ammonium bichromate, a large flow of inert gas of 6.65 nm3/h per 1 liter of solution, as well as low activity and stability of catalyst.

The closest in technical essence and the achieved result is a cooking method nickelchromium catalyst used in industry for the hydrogenation of benzene, comprising preparing a solution of dibasic acid chromium interaction of sodium bichromate with ethyl alcohol and nitric acid, neutralize it with baking soda, precipitation from solutions of the nitrate salts of Nickel and chromium soda at a temperature of 60-70aboutC and pH 7.0-7.3 is active nickelchromium composition, filtering and washing of the basic Nickel carbonate and chromium oxide hydrate, drying-calcining the catalyst mass with subsequent formation of the catalyst [2] the catalyst must meet the requirements of OST 113-03-314-86.

The disadvantage of this method are the two who becausehe crystals of Nickel on the surface of larger crystals of chromium oxide (III), resulting in the reduction of General and specific surface of the catalyst, which leads to loss of activity and stability of the catalyst.

The aim of the invention is to increase the activity and stability of the catalyst.

This goal is achieved by the proposed method, the preparation of the catalyst for hydrogenation of benzene, including coprecipitation active nickelchromium composition from a solution containing Nickel nitrate and chromium compound, in the presence of the precipitator, dehydration, drying and calcining the obtained mass and the subsequent formation of the catalyst, and as compounds of chromium using chromic anhydride, as precipitator urea, taken in an amount of 30-60 wt. from stoichiometric to the amount of Nickel and chromium, dehydrate the resulting mass by parki and operations Parke, drying and calcining is carried out in one apparatus.

A distinctive feature of the proposed method is the use of chromium trioxide as chromium compounds and urea as a precipitant in the amount of 30-60 wt. from stoichiometric to the amount of Nickel and chromium and a combination of operations by dehydration, drying and calcining the h and stability to the value of 0.48.

As the authors found, the content of active components from a solution of Nickel nitrate and chromic anhydride in the presence of urea proceeds through the formation of basic Nickel carbonate, ammonium chromate and chromate Nickel. Radiographic analysis showed that when termorasshirennyi mixture along with the Nickel oxide and chromium oxide, the formation of highly dispersed systems NiCr2O4providing a higher activity and stability of catalyst. And the content of spinel (NiCr2O4in the catalyst prepared by the claimed method, increases in the order compared to the prototype.

The use of urea in the selected limits due to the fact that the exorbitant values not achieved the goal: when using fewer than 30% disappears additive effect of urea as substances that promote the formation of fine-dispersed catalyst. When using more than 60% of the process of thermal decomposition catalyst mass occurs with a pronounced exothermic effect (overheating 300-350aboutC), which leads to the formation of coarse (up to 43 nm) of Nickel oxide and, accordingly, the loss of eccentricity 450 g/l added 29 g of chromic anhydride, heated to 80aboutAnd add the specified amount of urea required for the formation of the basic Nickel carbonate NiCO32Ni(OH)2and ammonium chromate. The resulting suspension in a thin layer is subjected to evaporation, drying and calcination at a temperature of 400aboutC for 1 h Get catalyst the following chemical composition, wt. NiO 63,0; Cr2O327,0.

The activity of the obtained catalyst is estimated by the rate of hydrogenation of benzene at 100aboutC and a pressure of 1 ATM. Stability as the ratio of the rate of hydrogenation of benzene after overheating of the catalyst at 400aboutC for 1 h in a mixture to the speed of hydrogenation to overheating of the catalyst. The particle size of 8 nm NiO, Cr2O3fine particles (beyond the sensitivity of the diffractometer Dron-3).

The results of the implementation examples 1-5 preparation and testing nickelchromium catalyst for the hydrogenation of benzene and similar catalyst, obtained in a known manner, are presented in the table.

As follows from the above examples, the catalyst obtained by the proposed method outperforms well-known activity 1.1-1.4 times and stability in 2-2,3 times.

1. The METHOD of PREPARATION NICKELCHROMIUM CATALYST FOR the HYDROGENATION of BENZENE, including coprecipitation active nickelchromium composition from a solution containing Nickel nitrate and chromium compound, in the presence of the precipitator, dehydration, drying and calcining the resulting mass with subsequent formation of a catalyst, characterized in that, to improve the activity and stability of catalyst, as compounds of chromium using chromic anhydride, and as precipitator - urea.

2. The method according to p. 1, characterized in that the urea charge in the amount of 30 to 60 wt.% from stoichiometric to the amount of Nickel and chromium.

3. The method according to PP. 1 and 2, characterized in that the dehydration is carried out by parki and operation of parki, drying and calcining combine.

 

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SUBSTANCE: invention relates to catalysts used in isoamylenes-into-isoprene dehydrogenation process and contains, wt %: iron oxide 62-75.4, potassium carbonate 12-21.5, chromium oxide 1-3, potassium hydroxide 0.5-2.5, sulfur 0.1-2.0, ammonium nitrate 0.1-2.0, silicon dioxide 1-5, calcium carbonate 1-5, and cerium nitrate 1-3.

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2 tbl, 2 ex

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1 tbl, 12 ex

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EFFECT: increased mechanical strength and wear resistance of catalyst.

1 tbl

FIELD: industrial organic synthesis catalysts.

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EFFECT: increased mechanical strength and wear resistance of catalyst.

1 tbl

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