RU2125485C1 - Method of preparing soluble molybdenum epoxidation catalyst - Google Patents

Abstract

FIELD: catalysts for petrochemical syntheses. SUBSTANCE: storage-stable molybdenum epoxidation catalyst is prepared by dissolving molybdenum metal powder in heated solvent containing ethanol and concentrated ethylbenzene peroxide in oxidized ethylbenzene. Operation is carried out in two-reactor system. In the first reactor, molybdenum-solvent mixture is agitated and then transferred into the second reactor, which also receives ethanol in amount 50% of initially used ethanol and, contained therein, radical reaction inhibitor in quantity from 0.0005 to 0.1 wt %. EFFECT: reduced molybdenum sludge formation due to additional stabilization of dissolved molybdenum forms. 3 cl, 7 ex

Description

 The invention relates to a method for preparing a hydrocarbon-soluble epoxidation catalyst.

 The processes of epoxidation of olefin hydrocarbons by organic hydroperoxides are widely used in the technology of basic organic and petrochemical synthesis. The most widely used catalysts for these processes are compounds of heavy metals of variable valency. The most preferred of them for use in industrial technology was molybdenum in the pentavalent or hexavalent state, in the form of solutions of its carboxylates, diketonates, alcoholates and diolates in an appropriate solvent.

A known method of producing molybdenum-containing catalysts soluble in organic solvents by the reaction of a solid molybdenum-containing substance or metallic molybdenum with organic hydroperoxide in the presence of alcohols with 1-4 carbon atoms, including propylene glycol, at a temperature of 25-100 ^o C. But under these conditions insufficiently high solubility of molybdenum and the stability of the catalyst [Patent of Germany N 1517983, publ. 07/10/75].

 Closest to the claimed invention is a method for producing a molybdenum-containing catalyst described in the article Karpenko L.P., Serebryakova B.R. et al. [Synthesis of an epoxidation catalyst based on metal molybdenum. Karpenko L.P., Serebryakov B.R., et al., "Journal of Applied Chemistry", 1975, 48, No. 8, p. 1706-1709.], Which consists in the interaction during heating and stirring of metal molybdenum with ethylbenzene hydroperoxide in ethyl alcohol. The article shows the effect of the amount of ethyl alcohol on the resulting catalytic complex. But under the described conditions, the storage stability of the catalyst is not high enough.

 The essence of the claimed invention is a method for producing a storage-stable molybdenum-containing epoxidation catalyst by dissolving when heated metal powder of molybdenum in a solvent containing ethanol and concentrated ethylbenzene hydroperoxide in oxidized ethylbenzene, the mixture of metal powder molybdenum and ethanol is heated in the first reactor with stirring, and hydroper in the second reactor, in the second reactor add an alcohol solution of inhibitory radical reactions at a concentration of 0.0005-0.01 wt.%, the amount of added alcohol is up to 50% of the initial catalyst preparation. The alcohol solution of the inhibitor can be introduced into the container for storage of the catalytic complex and / or at any point in the technological scheme for preparing the catalyst between the container for storage of the catalyst and the epoxidation reactor. Phenol, alkylphenol, space-hindered phenols (such as ionol or Mannich base), or mixtures thereof are used as an inhibitor of radical reactions.

 The proposed method allows to reduce the formation of molybdenum-containing sludge due to additional stabilization of the dissolved forms of molybdenum. This stabilization method can also be used in combination with other known methods of stabilization of molybdenum-containing non-aqueous solutions used as catalysts and, in particular, in the epoxidation reaction of propylene with ethylbenzene hydroperoxide.

 We have not found the proposed method for producing an epoxidation catalyst in the literature, which indicates its compliance with the criterion of "novelty." The introduction of a new set of distinguishing features in combination with the achieved effect (the combined use of an additional supply of ethanol and the addition of radical reaction inhibitors) has not been described in any similar method, which indicates compliance with the criterion of "inventive step". The possibility of using the proposed method for producing an epoxidation catalyst in industry shows the compliance of the invention with the criterion of "industrial applicability".

 The proposed method is illustrated by the following examples.

 Example 1 (comparative).

The experiment is carried out on a continuous installation consisting of two reactors, each of which has a volume of 3 l, a sump of 4.5 l and a container for storing the prepared catalyst with a volume of 20 l. The reactors are equipped with mixing and loading devices. All equipment is made of stainless steel and equipped with thermostatic devices. At all stages of the preparation of the catalyst solution, a temperature of 50 ^° C. was maintained. 6 g / h (0.06257 mol) of powdered metallic molybdenum, 500 g / h of fortified oxidized ethylbenzene containing 25 wt. % HPEB (0.9058 mol) and 500 g / h ethanol ((92% solution) (10 mol). The molar ratio of Mo: HPEB: ethanol is 1: 14.5: 160. The reaction mixture from the first reactor flows to the second and then into the sump, in which the separation of insoluble metal molybdenum occurs. After separation of the insoluble molybdenum, the catalyst solution enters the storage tank. The dissolved molybdenum content in the prepared catalyst is 0.55 wt.%. The solution is stored at 40 ^o C. 15 days in solution, the content of dissolved molybdenum and was 0.27 wt.%, which corresponded to 50% of the original.

 Example 2

 The experiment is carried out according to the method of example 1. An additional 25 g / h (5 wt.% Of the initially added amount) of ethyl alcohol (92% solution) containing 0.001 wt.% Ionol is additionally introduced into the second reactor. The molar ratio of molybdenum: HPEB: ethanol is 1: 14.5: 167.8. The content of dissolved molybdenum in the prepared solution is 0.55 wt.%.

The solution was stored at 40 ^° C. After 15 days, the dissolved molybdenum content in the solution was 0.51%, which corresponded to 92.7% of the original.

 Example 3

The experiment was carried out according to the procedure of Example 1 at a temperature of 60 ^° C. 7 g / h (0.073 mol) of powdered metal molybdenum, 400 g / h of strengthened oxidized ethylbenzene containing 25 wt.% HPEB (0.7246 mol) were introduced into the first reactor, and 400 g / h of ethyl alcohol (92% solution) (8 mol). The molar ratio of molybdenum: HPEB: ethanol is 1: 9.93: 109.6. An additional 200 g (50 wt.% Of the initially added amount) of ethyl alcohol (92% solution) containing 0.0005 wt.% Mannich Base is further added to the second reactor. The content of dissolved molybdenum in the prepared catalyst 0.67 wt.%
The solution was stored at 5 ^° C. After 15 days, the dissolved molybdenum content in the solution was 0.66 wt.%, Which corresponded to 98.5% of the original.

 Example 4

The experiment was carried out according to the procedure of Example 1 at a temperature of 70 ^° C. 7 g / h (0.073 mol) of powdered metal molybdenum, 500 g / h of strengthened oxidized ethylbenzene containing 25 wt.% HPEB (0.9058 mol) were introduced into the first reactor, and 400 g / h of ethyl alcohol (92% solution) (8 mol). The molar ratio of molybdenum: HPEB: ethanol is 1: 12.41: 109.6. An additional 100 g (25% by weight of the initially added amount) of ethyl alcohol (92% solution) containing 0.005% by weight of phenol is further added to the second reactor. The content of dissolved molybdenum in the prepared catalyst 0.67 wt.%
The solution was stored at a temperature of 60 ^o C. After 15 days in the solution, the content of dissolved molybdenum was 0.63 wt.%, Which corresponded to 94% of the original.

 Example 5

The experiment is carried out according to the method of example 1 at a temperature of 50 ^o C. In the first reactor is introduced 8 g / h (0.08342 mol) of powdered metal molybdenum, 500 g / h of strengthened oxidized ethylbenzene containing 25 wt.% HPEB (0.7246 mol) and 500 g / h of ethyl alcohol (92% solution) (10 mol). The molar ratio of molybdenum: HPEB: ethanol is 1: 8.69: 119.9. An additional 50 g (10% by weight of the initially added amount) of ethyl alcohol (92% solution) containing 0.01% by weight of nonylphenol was further added to the second reactor. The content of dissolved molybdenum in the prepared catalyst 0.76 wt.%
The solution was stored at a temperature of 60 ^o C. After 15 days in the solution, the content of dissolved molybdenum was 0.7 wt.%, Which corresponded to 92% of the original.

An additional 50 g (10% by weight of the initially added amount) of ethyl alcohol (92% solution) containing 0.01% by weight of nonylphenol is introduced into the line for selecting the catalyst solution from the catalyst storage tank. The content of dissolved molybdenum in the catalyst after adding alcohol, according to the analysis, became 0.65 wt.%. The resulting solution was taken and stored at a temperature of 60 ^o C. After 15 days, the content of dissolved molybdenum in the solution was 0.65 wt.%, Which corresponded to 100% of the original.

 Example 6

 The experiment is carried out according to the method of example 5. As a radical reaction inhibitor, a mixture is used consisting of ionol and alkyl phenol with their content in an ethanol solution of 0.001 and 0.001 wt.%, Respectively.

 After 15 days of storage, the content of dissolved molybdenum in the catalyst is 100% of the original.

 Example 7

Samples of the epoxidation catalyst obtained from the recipe of examples 1 and 4 were tested in the epoxidation reaction of propylene with a 25% solution of HPEB in oxidized ethylbenzene at a temperature of 110 ^o C with a molar ratio of HPEB and propylene reagents equal to 1: 6 and HPEB and molybdenum equal to 1: 0,0005. The experiments were carried out in an autoclave made of stainless steel. The duration of each experiment was 1.5 hours. At the end, it was found that the HPEB conversion was 98.7 and 98.8%, respectively, and the selectivity of propylene oxide was 82.6 and 82.9 mol%, respectively.

 As can be seen from the above examples, the introduction of alcohol solutions of a phenolic type radical inhibitor into the prepared catalyst solution can dramatically increase the storage stability of the epoxidation catalyst.

Claims (3)

 1. The method of obtaining a soluble molybdenum epoxidation catalyst by dissolving when heated metal powder of molybdenum in a solvent containing ethanol and concentrated ethylbenzene hydroperoxide in oxidized ethylbenzene, characterized in that the dissolution is carried out in a cascade of two reactors, the mixture of metal powder molybdenum is heated in the first reactor with stirring solvent and served in a second reactor, to which ethanol is added in an amount up to 50% of the original taken and the preparation of the catalyst containing an inhibitor of radical reactions in an amount of 0.0005 - 0.1 wt.%.  2. The method according to claim 1, characterized in that the solution of the inhibitor in ethanol is added to the storage tank of the catalytic complex and / or to any point in the technological scheme for preparing the catalyst between the storage tank of the catalyst and the epoxidation reactor.  3. The method according to claim 1, 2, characterized in that as an inhibitor of radical reactions using phenyl, alkylphenol, spatially hindered phenols, such as ionol or Mannich base, or mixtures thereof.