Catalyst to obtain tertiary olefins

 

(57) Abstract:

Usage: catalytic chemistry, in particular the production of catalysts for production of tertiary olefins from the corresponding alkyl-tert-alkyl ethers. The inventive catalyst contains silica-modified alumina in the amount of 0.3 to 1.0 wt.%. The catalyst was prepared by impregnation of silica with a solution of aluminum salts. Dried and calcined. The calcined catalyst was subjected to purification with 20 - 100oC for 0.5 to 24 h in an aqueous solution of an acid or an aqueous solution exhibiting acidity during thermal decomposition. An aqueous solution is used in a molar concentration of 0.05 - 0.5 in the amount of from 1 to 20 volumes of purified substances. Dried and calcined. As an aqueous solution exhibiting acidity during thermal decomposition, it is preferable to use an aqueous solution of ammonium salts, preferably ammonium acetate or propionate ammonium, or ammonium chloride. 2 C. p. F.-ly, 2 tab.

The invention relates to a catalyst for obtaining tertiary olefins decomposition of alkyl tert-alkyl ethers.

There are various methods of obtaining tertiary olefins. So, odnim corrosion and contamination has others, including the need to concentrate the acid prior to its secondary use. Other methods are based on the decomposition of the corresponding methyl esters in the presence of an appropriate catalyst systems. However, in most cases, the use of known catalysts leads to the formation of dalkilic esters after dehydration of the corresponding primary alcohols.

The reaction proceeds faster at higher temperatures. Some of the known catalysts require the use of relatively high temperatures, which leads to loss of alcohols with the appropriate filing new portions of alcohols with primary esterification reaction.

In addition, the formation of dealkylation requires more complex installations, because of the need to separate dialkylamide from tertiary olefins. In addition, the formation of significant quantities of dealkylation requires dehydration of primary alcohols before returning to the loop, otherwise during the esterification reaction may be divided phases, with the possible formation of tertiary alcohols.

Other disadvantages when conducting the reaction outside the specified temperature range applies to my problems disappear if the decomposition of tert-alkyl ethers is carried out in the presence of catalysts consisting of activated alumina, modified partial replacement of surface Oh-group silanolate group, as described in Italian application N 1001614 and N 1017878 owned by the authors and the present invention. However, the application specified an activated aluminum oxide leads to the formation of alkyl ethers, with a consequent reduction in the number of primary alcohols regeneration, even when the reaction proceeds at moderate temperatures.

In US patent N 4254296 the use of the catalyst of the crystals of silicon dioxide, modified by cations, oxides of such metals as aluminum and boron, with a much better performance than the activated alumina modified with silanolate groups. However, the production of this catalyst is expensive and too difficult. In addition, the catalyst siliconized aluminum oxide cannot long be used, because it is impossible to limit the concentration of by-products to the extent provided economically quantitative allocation of the resulting product. Large number is acii or separation.

In the application for European Patent N 0261129 shown that when using a catalyst consisting of silicon dioxide, modified by the addition of aluminum oxide in an amount of 0.1-1.5 wt. with respect to the oxide of silicon, it is possible to obtain a high degree of conversion, provided that you use the silica of high purity.

In this application found that the conversion obtained with this catalyst can be significantly increased if the method of preparation of the catalyst, providing for the cleanup.

The increase in conversion is obtained mainly using commercial silica, and oxide of high purity silicon conversion is several orders of magnitude higher.

As shown in the above examples, it is important to carry out the cleanup stage, including the impregnation of alumina, if you want to get better results.

According to the invention the catalyst used to obtain the tertiary olefins from the corresponding alkyl-tert-alkyl ethers and consisting of silicon dioxide, modified by the addition of aluminum oxide in the amount of 0.3 to 1.0 wt. with respect to the oxide of silicon, characterized in that sleduyushei drying and calcination, the material is then subjected to purification using aqueous solutions of acids (such as Hcl, H2SO4and so on ) or aqueous solutions exhibiting acidity during thermal decomposition, with the subsequent washing, the secondary drying, and secondary calcination.

Preferred aqueous solutions that detect acidity decomposition, are ammonium salts, in particular ammonium acetate, propionate, ammonium and ammonium chloride.

Cleaning is preferably carried out at a temperature of 20-100aboutDuring the period of time from 0.5 to 24 hours

Aqueous solutions are preferably used in molar concentrations of 0.05-0.5 in the amount of 1-20 volumes of substances subject to the clearing.

The way in which the tertiary olefins, mainly lies in the interaction of the corresponding alkyl-tert-alkyl ethers in the presence of a catalyst obtained as described above and consisting of an oxide of silicon with the addition of aluminum oxide in the amount of 0.3-1 wt. with respect to silicon dioxide.

The decomposition of alkyl tert-alkyl simple ester is carried out at temperatures equal to or below 500aboutWith, preferably between 130 and 350aboutC.

the Oia vapors recovered olefins when used temperatures of condensation.

The volumetric rate is expressed as hourly space velocity of fluid (COSI), the reaction is carried out at space velocities of from 0.5 to 200 h-1preferably at 1-50 h-1. Primary alcohols, which can be distinguished in the process of decomposition, described in the invention contain from 1 to 6 carbon atoms.

Various olefins obtained in a purified condition, include isobutylene, isoamylene, such as 2-methyl-2-butene and 2-methyl-1-butene, isohexane, such as 2,3-dimethyl-1-butane, 2,3-dimethyl-2-butane, 2-methyl-1-pentane, 2-methyl-2-pentane, 3-methyl-2-pentane(CIS and TRANS), 2-ethyl-1-butane, 1-methylcyclopentene and tertiary isoheptane.

The conversion of tert-alkyl ethers in primary alcohols and tertiary olefins is in quantitative agreement with thermodynamic data. Observed the formation of small amounts of dimers and trimers allocated to tertiary olefins, whereas tertiary alcohols are not formed.

Examples of preparation of the catalyst.

P R I m e R 1. The catalyst in the form of silicon dioxide, modified alumina, prepared as follows:

10 g of technical oxide silicon (A, Shell) in the composition, wt. Na2O 0,08 SO40,10 Al2O30,1 is I (add 0.5. Al2O3with respect to the oxide of silicon, then slowly dried at 120aboutC for 3 h and calcined at 500aboutC for 4 h

The resulting material is treated with 100 cm3solution of ammonium acetate (0,17 molar) at 50aboutC for 2 h

The substance will be separated from the solution and washed with deionized water (3 volume 100 cm3), dried in an oven at 120aboutC for 3 h and calcined at 450aboutC for 4 h

P R I m m e R 2. According to the method of example 1, the preparation of the catalyst used technical alumina Shell V.

But unlike the method proposed in example 1, 10 g of silica impregnated with 8.5 cm3an aqueous solution containing 0,515 g 9-aqueous aluminum nitrate (added 0.7 wt. Al2O3with respect to the oxide of silicon).

P R I m e R 3. The preparation of the catalyst according to the method of example 1 using technical silicon oxide Shell 980B.

But unlike the method proposed in example 1, 10 g of silica impregnated with 8.5 cm3an aqueous solution containing 0,736 g 9-aqueous aluminum nitrate (added 1 wt. Al2O3with respect to the oxide of silicon).

10 g of silica treated with 100 cm3solution of ammonium acetate (0,17-molar solution) at 50aboutC for 2 h

Then the substance is separated from the solution and washed with deionized water (3 times with 100 cm3), dried in an oven at 120aboutC for 3 h and calcined at 450aboutC for 4 h

The resulting material is impregnated with 8.5 cm3an aqueous solution containing 0,736 g 9-aqueous aluminum nitrate (added 1 wt. Al2O3with respect to the oxide of silicon), then slowly dried at 120aboutC for 3 h, and calcined at 500aboutC for 4 h

In comparison with example 3, the cleaning is performed prior to the impregnation of Al2O3.

P R I m e R s 5-7 (comparative). The catalysts are prepared (examples 5, 6 and 7) by the methods described in examples 1, 2 and 3, respectively, but without cleaning after the first drying and the first calcination.

P R I m e R s 8-10 (comparative). The catalysts are prepared (examples 8, 9 and 10) by the methods described in examples 5, 6 and 7, respectively, but instead of using commercial silica Shell 980B use high-purity silicon oxide AKZO following composition, wt. Na2O 0,02 SO40,15 Al2O30.1 and m e R s 11-20. The catalysts prepared according to examples 1-10, used for tertiary olefins by the decomposition of methyl tert-butyl ether (MTBE). The conditions of the reaction as follows: the temperature of the catalyst layer, aboutWith 130 CASE, h-14 Inlet pressure, ATM 1,4

The results are shown in table.1, from which one can see the benefits of purification of the catalyst. The degree of conversion is much higher than when using catalysts prepared from technical oxide silicon by known methods, and it is also clear that the degree of conversion is higher than in cases when the catalysts are prepared from high purity silica known methods.

From table. 1 also shows that cleanup is conducted prior to the impregnation of Al2O3gives a slight advantage in the sense of not increasing transformations, and most likely due to the increase in the magnitude of the transformation.

In table.2 shows additional examples 21-25, demonstrating the preparation of the catalyst in accordance with the existing examples 2 and 3 in the description of the invention and using the conditions described in examples 11-20.

1. CATALYST TO OBTAIN TERTIARY OLEFINS from the corresponding alkyl - 1.0 wt.% with respect to silicon dioxide, obtained by impregnation of silica with a solution of an aluminum salt followed by drying and calcination, wherein the modified silica after calcination purified aqueous acid solution or aqueous solution exhibiting acidity during thermal decomposition, with a molar concentration of 0.05 - 0.5 in the amount of from 1 to 20 volumes of the purified substance at 20 - 100oC for 0.5 to 24 h, followed by washing, drying and calcination.

2. The catalyst p. 1, characterized in that an aqueous solution exhibiting acidity during thermal decomposition, using an aqueous solution of ammonium salts.

3. The catalyst p. 2, characterized in that as the ammonium salts used ammonium acetate, or propionate ammonium, or ammonium chloride.

 

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