A method of producing a catalyst for dehydrogenation of isoamylenes in isoprene

 

(57) Abstract:

The invention relates to the field of catalytic processes, in particular the production of a catalyst for the dehydrogenation of isoamylene in isoprene, and can be used in the production of synthetic rubber. The essence of the invention: method of preparation zhelezohromovye catalyst dehydrogenation of isoamylenes. With the purpose of obtaining a catalyst with high activity and selectivity, the main component of the catalyst is finely ground iron oxide before forming treated with an aqueous solution of potassium carbonate and potassium hydroxide, taken in the mass ratio (20 - 100) : 1, at 85-90oC for at least 6 hours Conducting such pre-treatment under other equal conditions for the synthesis of catalyst and process for the dehydrogenation of isoamylene can achieve outputs of isoprene missed and reacted isoamylene at the level of, respectively, 40 and 41 and 90,0 is 91.5 wt.%.

The invention relates to the production of catalysts for the dehydrogenation of olefinic hydrocarbons, in particular to a method for preparing a catalyst for the dehydrogenation of isoamylene in isoprene, which is a monomer for the production of sintet the s by mixing dry powdered iron oxide, zirconium, chromium, oxides or easy to decompose to oxides of compounds of molybdenum and cerium, Portland cement, followed by stirring with an aqueous solution of alkali promoters, molding, drying and calcining the obtained catalyst.

The main disadvantage of this method is to obtain catalysts with high enough performance.

[Ed. mon. The USSR 426412, class B 01 J 23/86, 1972;

Auth. mon. The USSR 1267657, class B 01 J 23/88, 1984;

Auth. mon. The USSR 1415684, class C 07 C 11/18, 5/333, 1986;

Auth. mon. The USSR 1769437, CL 01 J 37/04, 23/88, 1990.]

Closest to the claimed technical solution is apooo obtain catalyst for dehydrogenation of isoamylenes in isoprene containing chromium oxide (3), potassium carbonate, potassium silicate, zirconium dioxide and iron oxide used in industry for the dehydrogenation of isoamylenes and ethylbenzene (catalyst K-24) [ed. mon. The USSR 426412, CL 01 J 23/86 1972].

For the preparation of the catalyst according to the prototype of a mixed oxide of iron with chromium oxide and zirconium dioxide, dry mixture of ingredients is stirred for 20 minutes to Prepare an aqueous solution of potassium carbonate (K2CO3and the solution is mixed with the dry mixture ingredienellulose and plastifitsirovanie mixture of the obtained paste ekstragiruyut catalyst pellet. The granules are dried for 24 h at 150oC, and then calcined 2 hours at 650oC. In finished form obtained according to the prototype of the catalyst has the following composition, wt.%:

Zirconium oxide (3) - 3,5 - 6,0

The potassium carbonate is 19.5 - 25,0

The potassium silicate - 2,0 - 2,6

Zirconium oxide (4) - 2,4 - 3,0

Iron oxide (3) - Rest

and provides conversion isoamylenes in the isoprene level 32,0 - 38,0 wt.% when the selectivity of transformation at the level of 83 to 85 wt.%.

A significant drawback of such a method of preparation of catalyst for dehydrogenation of isoamylenes in isoprene is not sufficiently high activity and selectivity of the resulting catalyst. In addition, obtained according to the prototype of the catalyst is characterized by instability.

The essence of the invention is a method of producing a catalyst for dehydrogenation of isoamylenes in isoprene, characterized in that in order to obtain a catalyst with high activity and selectivity, and stability of its quality, fine powder of iron oxide before the mixture is treated with an aqueous solution of potassium carbonate and potassium hydroxide, taken in the mass ratio (20 - 100) : 1 at a temperature of 85 - 90oC in accordance with the structure of the catalyst stable quality with higher catalytic indicators: yield of isoprene on missed isoamylene reaches 40,0 - 41,0 wt.% when selectivity at the level 90,0 is 91.5 wt.%.

As it was experimentally found that pre-treatment for a long period (at least 6 hours before the establishment of the constancy of the pH of the mixture) of iron oxide to neutralize a strong acid centers present on its surface.

The presence of such a strong acid sites in the catalyst composition of the dehydrogenation of isoamylenes leads to a decrease in their activity and selectivity, as well as to instability of the quality of the catalysts.

The hallmark of the invention are pre-processing component of the catalyst is iron oxide - before mixing with other components of the catalyst with an aqueous solution of potassium carbonate and potassium hydroxide, taken in the mass ratio (20 - 100) : 1 at a temperature of 85 - 90oC for at least 6 hours before the establishment of the constancy of the pH of the mixture.

When comparing essential features of the invention with those of the prototype revealed that they are new and are not described in the prototype, where you can make a conclusion about conformity of the proposed technical solution the criterion of "novelty".

The introduction of new distinctive features combined in the Noah invention meets the criterion of "industrial applicability", confirm the following set of conditions:

the invention is intended for use in industry;

for the invention as it is described in the independent claim, confirmed the possibility of its implementation using the steps described in the application of tools and techniques.

The method is as follows: mix required quantity of finely ground iron oxide with an aqueous solution of potassium carbonate and potassium hydroxide and incubated under certain conditions, for at least 6 hours, then the mixture is injected required amounts of the other ingredients of the catalyst. Thoroughly mixed and the resulting mixture is brought to a paste with continuous stirring at the expense of parki catalyst mass. The paste for one hour until tender mass moulding add the calculated quantity of potassium silicate (liquid glass). Obtained in the mixer weight with humidity 20 - 30% is sent to the granulator in which the extrusion is formed into pellets of the catalyst. The granules are dried at 150oC for 24 h, and then calcined at 650oC for 3 to 6 hours

Example 1 (comparative).

AZN 352.5 g of iron oxide mixed asego 100 g of potassium carbonate and 12.5 g of potassium silicate. The mixture was stirred until the formation of homogeneous plastic mass. Catalyst mass after plasticization was molded by extrusion in worms with a diameter of 3.5 - 4.0 mm, dried at 120oC and progulivali at 650oC for 3 hours. Received the catalyst had the following composition

Iron oxide - 70,5

Potassium carbonate - 20,0

The chromium oxide - 4,5

The Zirconia - 2,5

Silicate of potassium - 2,5

The catalyst was tested in the reaction of dehydrogenation of isoamylenes in a laboratory flow reactor type fixed bed of the catalyst at a temperature of 600oC when diluted raw water vapor in a molar ratio of 1 : 20 and a feed rate of the hydrocarbon 1.0 l/HP kW.h. Contact the gas was analyzed chromatographically to obtain converged results. The outputs of isoprene missed and reacted isoamylene respectively 37.6 85,0 wt.%.

Example 2.

The catalyst was prepared analogously to example 1, but in contrast to example 1, the iron oxide was subjected to pre-treatment with a solution of potassium carbonate and potassium hydroxide, taken in a mass ratio of 20 : 1, and containing 80 ml of a solution of 100 g of potassium carbonate and 5 g of potassium hydroxide for 5 h under continuous Pei for 30 min, was plastifitsirovanie and shaped worms catalyst. The resulting worms were dried at 120oC and then was hot for 3 h at 650oC.

The prepared catalyst was tested under the reaction conditions with a dehydrogenation isoamylenes analogously to example 1. The outputs of isoprene missed and reacted isoamylene respectively 39,1 and 90.9 wt.%.

Example 3.

The catalyst was prepared analogously to example 1, but in contrast to example 1, the iron oxide was subjected to pre-treatment with a solution of potassium carbonate and potassium hydroxide, taken in a mass ratio of 60 : 1, and containing 80 ml of a solution of 10 g of potassium carbonate and 1.67 g of potassium hydroxide for 6 hours with continuous stirring at 85-90oC. Then the catalyst was prepared in accordance with example 2.

The prepared catalyst was tested under the reaction conditions of the dehydrogenation of isoamylenes analogously to example 1. The outputs of isoprene missed and reacted isoamylene respectively 41,0 and 91.3 wt.%.

Example 4.

The catalyst was prepared analogously to example 1, but in contrast to example 1, the iron oxide was subjected to pre-treatment with a solution of potassium carbonate is Aliya for 6 hours with continuous stirring at 85 - 90oC. Then the catalyst was prepared in accordance with example 2.

The prepared catalyst was tested under the reaction conditions of the dehydrogenation of isoamylenes analogously to example 1. The outputs of isoprene missed and reacted isoamylene respectively 38,5 and 89.3 wt.%.

Thus, as can be seen from the presented data, pre-processing of finely ground iron oxide with an aqueous solution of potassium carbonate and potassium hydroxide, taken in the mass ratio (20 - 100) : 1, at 85-90oC for at least 6 hours results in a catalyst with high activity and selectivity in comparison with the prototype.

The method of preparation zhelezohromovye catalyst dehydrogenation of isoamylenes in isoprene containing iron oxide, chromium oxide (3), potassium carbonate, potassium silicate and zirconium dioxide, comprising mixing the components, molding, drying and calcination, wherein the fine iron oxide before mixing with other components of the catalyst treated with an aqueous solution mixture of potassium carbonate and potassium hydroxide, taken in the mass ratio (20 - 100) : 1, at 85 - 90oC for at least 6 hours

 

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FIELD: hydrogenation-dehydrogenation catalysts.

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.

EFFECT: increased mechanical strength, resistance to saturated steam and moisture, and stability during long-time operation.

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