The method of producing isobutylene skeletal isomerization of n - butylenes

 

(57) Abstract:

Usage: petrochemistry. Essence: the skeletal isomerization of n-butylenes is carried out by contacting a mixture containing the solvent and n-butylenes in a molar ratio of 0.5-10, with a catalyst at a temperature of 350-500oC and a pressure of 1-5 atmospheres. As catalyst, use aluminum oxide obtained by hydrolysis of aluminum alcoholate of the General formula Al(or SIG)3where R is alkyl WITH2+with high activity and stability during operation. Effect: increase the processability of the way by improving the stability and activity of the catalyst. 1 C.p. f-crystals, 1 table.

The invention relates to the petrochemical industry, in particular for the isomerization of n-butylenes in the isobutylene used in industrial organic synthesis, including the production of methyl tertiary butyl ether - a high-octane component of motor fuels.

There is a method of isomerization of n-butylenes in the isobutylene by the contacting of the feedstock containing normal butylenes, with a catalyst containing molecular sieve zeolite like from the group SAPO, FAPO, CoAPSO, MnAPSO, MgAPSO, when introduced into the reaction mixture is from 0.1 to 5% water. [Patent Of Satara.

There is a method of isomerization of n-butylenes in the isobutylene and catalyst for the implementation of this method on the basis of alumina-modified silica. Deposition of silicon oxide is carried out by contacting the aluminum oxide at an elevated temperature with vapor disiloxane or 2,3-amoxicillinum. Isomerization of n-butylenes in the isobutene is carried out in the presence of water vapor in the dilution of 0.01-1 mol of water per mol of butylene [Patent UK 2129701, 1984]. The disadvantage of this catalyst and method of its preparation is the heterogeneity of the distribution of silicon oxide on the surface of aluminum oxide, which leads to low selectivity of isomerization.

There is a method of isomerization of n-butylenes in the isobutylene at a temperature of 400-550oC at atmospheric pressure in the environment of water vapor in a fixed bed catalyst containing 0.1-10 wt. % fluoride, aluminum oxide [French Patent 2484400, 1981]. The disadvantage of this method is the low output isobutylene.

In the production method of the catalyst for isomerization of n-butylenes in the isobutylene [USSR Author's certificate 1319893, 1987] proposed to introduce in the aluminum hydroxide prior to moulding activating doba is I low activity of the catalyst due to the low specific surface activator, and low stability of the catalyst.

The closest entity is a method of producing isobutylene by contacting a mixture containing water and n-butylenes in a molar ratio of 0.5-10, with a catalyst at a temperature of 350-550oC and a pressure of 1-5 atmospheres. [The Patent Of The Russian Federation 2135443, 1999]. The process is performed on the catalyst skeletal isomerization containing 5-15 wt.% surface compounds of General formula where n= 1,2, dispersed on alumina, with the following content elements in the catalyst, wt.%:

The fluorine - 2-10

The silicon oxide is 0.5 - 3,15

Alumina - Rest

Silicofluoride compounds on alumina proposed to apply two options:

1 - when mixing 20-80oWith subsequent drying, calcination and hydrothermal treatment;

2 - impregnated granules of alumina with solutions of compounds SiF6when 20-80oWith subsequent drying, calcination and hydrothermal treatment.

The disadvantage of this method is the low stability of the isomerization catalyst.

The task of the invention to create a more technologically advanced compared to the prototype of the process of obtaining isobutylene skeletal izmeritelnaya operation.

The essence of the invention lies in the method of producing isobutylene skeletal isomerization of n-butylenes by contacting a mixture containing the solvent and n-butylenes in a molar ratio of 0.5 to 10, at a temperature of 350-500oC, a pressure of 1-5 atmospheres and weight feed rate of n-butylenes 0.2 to 2 h-1in the presence of a catalyst. The method differs in that the catalyst used aluminum oxide obtained by hydrolysis of aluminum alcoholate of the General formula Al(or SIG)3where R is alkyl WITH2+and the alcoholate of aluminum are intermediate products of the industrial synthesis of higher fatty alcohols. The diluent present in the isomerization of n-butylenes is nitrogen.

The catalyst for the skeletal isomerization is prepared by hydrolysis of aluminum alcoholate of the General formula Al(OR)3dilute solution of nitric acid, while maintaining a pH of 3-5, which provides optimal conditions the precipitate.

The resulting mixture advocate for the separation of aqueous and organic layers. The organic layer solution of alcohols C2+in kerosene, water - suspension of aluminum hydroxide.

From the aqueous layer filtering allocate the precipitate of aluminum hydroxide is ablaze shows the performance of the catalyst depending on the processing mode.

Example 1 (comparative prototype). The way the skeletal isomerization of n-butylenes in the isobutylene in the catalyst having a surface group composition where n=1,2.

To the prepared suspension of aluminum hydroxide was added with stirring a solution of ammonium silicofluoride is based 9,38 g of salt per 100 g of aluminum hydroxide (in terms of aluminum oxide). The temperature in the apparatus 80oWith, the application time is 8 hours with continuous stirring. After applying the suspension is filtered and molded in the form of extrudates. Drying of the catalyst is carried out at 120oC for 3 hours. The calcination of the catalyst is carried out at a temperature of 550oC for 3 hours. After the stage of calcination, the catalyst is subjected to hydrothermal treatment at a temperature of 550oC for 3 hours. Isomerization of n-butylenes is carried out at 475oWith a molar ratio water: butylene 3: 1. The table below shows the performance after 1 hour the catalyst.

Example 2 (comparative prototype). Similar to example 1, but shows the performance after 5 hours the catalyst.

The table shows that after 5 hours the catalyst, despite the hydrothermal treatment, reduce the congestion, the authors did not give.

Example 3. The way the skeletal isomerization of n-butylenes to isobutylene on the catalyst is aluminum oxide obtained by hydrolysis of a mixture of aluminum alcoholate.

Pre-receive an isomerization catalyst, for which a 20% solution in kerosene of aluminum alcoholate of the General formula Al(OR)3where R is alkyl WITH2+representing intermediate products industrial synthesis of higher fatty alcohols, is subjected to hydrolysis with nitric acid, maintaining the pH 3-5 (the concentration of the aqueous acid solution is 0.5 wt.%) at a temperature of 60oWith atmospheric pressure for 3 hours.

The resulting mixture defend 1 hour, divided into water and hydrocarbon layers. The precipitate of aluminum hydroxide is recovered from the aqueous layer by filtering, dried at a temperature of 150oWith, tabletirujut followed by calcining the obtained tablets at 550-600oC for 6 hours. A sample of catalyst has the following composition, wt.%:

The titanium oxide - 0,2

Iron oxide - 0,015

The silicon oxide - 0,024

Aluminum oxide (pseudonimity structure) - Rest

Thus obtained catalyst is used for the isomerization of n-butylenes.

Isomerization of n-butylenes are when the indicators are shown after 1 hour the catalyst.

As can be seen from the table, the proposed catalyst has the same performance as the catalyst for the prototype, but at a lower temperature. It speaks for its high activity.

Example 4. Similar to example 3. The difference is, what are the indicators of over 210 hours of catalyst.

This shows that the catalyst retains its high activity, selectivity even after 210 hours.

Example 5. Similar to example 3. The difference lies in the fact that the process is carried out at a temperature of 450oWith and the weight of the feed rate of n-butylenes 2 hours. -1.

As can be seen from the table, the catalyst under these conditions, also shows high activity and selectivity. This example shows the performance after 1 hour the catalyst.

Example 6. Similar to example 5. The difference lies in the fact that these numbers after 100 hours of operation catalyst.

As can be seen from the table, the catalyst has high activity, selectivity and stability in the conditions of example 5.

1. The method of producing isobutylene skeletal isomerization of n-butylenes by contacting a mixture containing the diluent and characterized in that the catalyst used aluminum oxide obtained by hydrolysis of aluminum alcoholate, the General formula Al(OR)3where R is alkyl WITH2+and the alcoholate of aluminum are intermediate products of the industrial synthesis of higher fatty alcohols.

2. The method according to p. 1, characterized in that as a diluent using nitrogen.

 

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FIELD: chemical industry; methods of production of the pure isobutene out of the isobutene-containing mixture.

SUBSTANCE: the invention is pertaining to the method of production of the pure isobutene out of the isobutene-containing mixture predominantly - out of hydrocarbon С4 with usage of the catalysis by the strong-acid cationite(s) including the liquid-phase interaction of the isobutene with the water at the temperature of from 60 up to 130°С in one or several sections at the stage of hydration, delamination of the being withdrawn from it stream(s), distillation of the unreacted hydrocarbons С4 from the hydrocarbon layer, decomposing of the tret-butanol in the section(s) at the stage of dehydration, separation of the formed isobutene from the water and its) purification and characterized by that isobutene and the total amount of the returned from the stage of dehydration fresh water is fed in the section of hydration in the total molar ratio from 1:0.4 up to 1:20, and it is preferential from 1:1 up to 1:5, in the straight-flow or bubbling mode in the absence of the emulsifier hydrate from 30 up to 97 % of isobutene. From the stage of the hydration in the stage of the dehydration at least one-third of the produced tret-butanol is fed in the stream, separated by the rectification from the layer of the unreacted hydrocarbons and containing from 5 up to 30 mass % of the water, and, possibly, the rest amount - in the stream of the water layer, at the total content of the different, than the isobutene, the hydrocarbons not exceeding their admissible quantity in the target isobutene, and from the stage of the dehydration the water at least partially is returned into the stage of the hydration. The presented method requires the low power input and the low metal input.

EFFECT: the invention ensures the low power input and the low metal input.

14 cl, 2 dwg, 4 ex

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