The way isomerization of olefins

 

(57) Abstract:

The invention relates to the isomerization of olefins and can be used in the petrochemical industry. The inventive method of isomerization of olefins includes passing couple, pure or diluted with an inert gas, over silicalite at a temperature of from 300 to 750C, the material containing at least 10 vol.% n-butene and possibly isobutene, with a maximum ratio of isobutene to n-butene 1:2, the deletion of this material over silicalite at a temperature of at least 500C and the extract stream containing an increased amount of isobutene. The technical result - selective increase in the content of isobutene in the target product, as well as reducing the amount of liquid by-products C > 5. 8 C.p. f-crystals, 7 PL.

The present invention relates to the isomerization of olefins. More specifically, it relates to improvements in the method of isomerization of olefins over silicalite.

Silicalite used at the same time, is an unmodified crystalline silica polymorph described in US 4061724 A, 06.12.1977 which provides a method of preparation silicalite.

In the US 4587375 A, 06.05.1986 description the
the implementation of the contact of this material with silicalite at a temperature of at least about 300oC in the presence of steam at a molar ratio water/raw materials of approximately 0.5-5.

However, when using this method retrieves the reaction products containing water. In addition, this method gives an excess quantity of liquid by-products. It was also established that the decontamination silicalite too significant for the industrial application of the method.

In this regard, there is a need to improve existing methods isomerization of olefins over silicalite.

The method according to the present invention includes the following operations:

a passing couple, pure or diluted with an inert gas, over silicalite at a temperature of from 300 to 750oC;

the supply of raw materials containing at least 10 vol.% n-butene and possibly isobutene, with a maximum ratio of isobutene to n-butene 1:2;

the transmission of this material over the specified silicalite at a temperature of at least 500oC;

removing a stream containing an increased amount of isobutene.

Definition silicalite above. Steam is passed over silicalite when temperately gas, used is a gas which does not react with silicalite at the same temperature, in particular, nitrogen). The dilution factor in the latter case may be from 1:99 to 99:1. Silicalite should be steam treated for at least 24 hours, preferably not less than 72 hours. Usually the process is conducted at atmospheric pressure, but higher or lower pressures may also be used. The volumetric rate shall be chosen in accordance with the duration of this operation, it usually ranges from 1 to 100 ml water per ml silicalite per hour, preferably about 10 ml/mlcas. All these are in flow rate represents the speed of expiration for volumes, measured at normal temperature and pressure.

Raw materials must contain at least 10% vol. n-butenes, and isobutene the contents of isobutene to n-butene should be maximum 1: 2 (preferably <1:5, even more preferably <1:10); other hydrocarbons are other major components. Preferably the material is a mixture of hydrocarbons, C4with a lower content of isobutene, in particular, obtained with the installation of methyl tert-butyl ether (MTBE). As the gases of thermal cracking.

Raw materials pass over silicalite at a temperature of at least 500oC, preferably from 500 to 650oC. This operation is performed in the gas phase, preferably at about atmospheric pressure. Flow rate can vary from 0.05 to 50 h-1preferably from 0.5 to 30 h-1.

Especially, it is preferable to separate the unreacted hydrocarbons present in the stream from isobutene, also present in the specified thread, and then return unreacted hydrocarbons back to the original raw materials.

Silicalite usually produced by extrusion. Usually silicalite combine (preferably during extrusion) with the materials of the inorganic matrix (often referred to as a binder), because it tends to be subjected to physical destruction and wear from friction during normal loading and unloading in the reaction zone, and during the process. When the matrix material is preferably the matrix was almost essentially free of hydrocarbon transformations; and especially preferred are extruded silicalite polymorphic silica catalysts, compiled by the IDA zirconium, silica-dioxide magnesium and clay; usually preferred is alumina.

The steam treatment can be carried out either before extrusion, preferably on a clean silicalite or after extrusion.

Life silicalite can be improved by periodic cessation of the source material and Stripping silicalite gas selected from the group comprising inert gases, oxidizing gases and their mixtures, preferably air, at a temperature of from 300 to 750oC, preferably from 450 to 675oC and most preferably about 600oC. Used in this case, the inert gas is a gas which does not react with silicalite at the same temperature, in particular nitrogen; an oxidizing gas used in this case is a gas, in particular oxygen, which react at the same temperature with carbon precipitation on silicalite education Akilov carbon. The Stripping is carried out at a pressure from atmospheric to 1 MPa, preferably from pressure above atmospheric to 0.5 MPa, most preferably about 0.3 MPa. The process continues until such time as the composition of the outgoing gas will not become virtually sootvetstvuyuschengo in the outgoing gas. Characteristics after regeneration is almost identical to the original.

Further, the invention is illustrated by the following examples.

Example 1

The mixture of hydrocarbon, C4with a lower content of isobutene received with the installation of MTBE, it had the following composition, wt.%:

Hydrocarbons, C3- 0,2

n-butane to 12.0

Isobutane - 31,2

1-Butene - 22,0

CIS-2-butene - 11,9

TRANS-2-uten - 18,4

Isobutan - 3,2

C5and more heavy - 1,1

Received industrial catalyst with the following characteristics:

(a) silicalite - 80 wt.%

the molar ratio of SiO2/Al2O3- 240

the size of the crystals - 0,001 - 0,01 mm

specific surface 357 m2/g

Delta d-28oC (2 theta) - 0,0035 nm (Co K-alpha x-ray diffraction)

the crystal structure is monoclinic

Na2O - <500 wt. parts per million

K2O - <500 wt. parts per million

(b) Al2O3binder - 20 wt.%

15 ml of the catalyst was treated with steam under the following conditions:

- the flow of 90 l of nitrogen and 190 ml of water per hour;

- rise of temperature from 25 to 550oC with a speed of 52.5oC/h, then the exposure at 550oC for 96 hours;

- atmospheric at 550oC, passing over him, the air flow 20 nl/h at atmospheric pressure.

Then over the catalyst missed raw materials under the following operating conditions:

- atmospheric pressure

- 550oC (isothermal reactor)

- volumetric flow rate of stream = 25 l/LCAS

- mode downstream

12 days supply of raw materials was stopped for Stripping catalyst air flow 30 IO per hour at 580oC and a gauge pressure of 0.3 MPa to until the concentration of CO2the output was not equal to 100 parts per million.

After that, the raw material is again passed over the regenerated catalyst under the above operating conditions.

The results are shown in table 1. The conversion and the yield was calculated as follows:

< / BR>
< / BR>
Table 2 shows the outputs for different hydrocarbons first fraction calculated by the formula with the appropriate changes.

Comparative example A

Example 1 was repeated, except that the processing operation of the catalyst ferry was omitted. Results are also presented in tables 1 and 2.

It is easy to see that pre-treatment of the catalyst vapor unexpectedly Gamboa 2), as well as reducing the amount of liquid by-products (C>5).

Example 2

Example 1 was repeated with the industrial silicalite catalyst without binder. Received commercial silicalite had the following properties:

the molar ratio of SiO2/Al2O3- 240

the size of the crystals - 0,001 - 0,01 mm

specific surface - 399 m2/g

Delta d-28oC (2 theta) - 0,0035 nm (Co K-alpha x-ray diffraction)

the crystal structure is monoclinic

Na2O - <500 wt. parts per million

K2O - <500 wt. parts per million

The results are presented in table 3. The transformation and the output was calculated as in example 1. In table 2, the outputs are calculated for various hydrocarbons first fraction, as was done in example 1.

Comparative example B

Example 2 was repeated, except that the processing operation of the catalyst ferry was omitted. Results are also presented in tables 2 and 3.

It is easy to see that pre-treatment silicalite catalyst not containing a binder, ferry led to a sharp increase of the service life of the catalyst (table 3) and output isobutene (table 2).

It should noted is certain silicalite catalyst without binder. The mixture of hydrocarbon, C4with a lower content of isobutene received from the installation of MTBE; it had the following composition, wt.%:

Hydrocarbons, C3- 0,2

n-butane - 11,3

Isobutane - 35,7

1-Butene - 19,2

CIS-2-butene - 12,2

TRANS-2-butene - 17,7

Isobutan - 1,8

C5and more heavy - 1,5

Received industrial catalyst with the following characteristics:

the molar ratio of SiO2/Al2O3and 50.4

the size of the crystals - 0,001 - 0,01 mm

specific surface 441 m2/g

Delta d-28oC - -

the crystal structure is <60% monoclinic

Na2O - <500 wt. parts per million

K2O - <500 wt. parts per million

The results are presented in table 4. The transformation and the output was calculated as in example 1. In table 5 the outputs calculated for the different hydrocarbons in the first fraction, as was done in example 1.

Comparative example C

Example 3 was repeated, except that the processing operation silicalite ferry was omitted. Results are also presented in tables 4 and 5.

Example 4

Example 2 was repeated with industrial silicalite catalyst without binder. Training was conducted on the basis of the or from the installation MTBE; she had the following composition, wt.%:

Hydrocarbons, C3- 0,1

n-butane - 12,4

Isobutane - 19,3

1-Butene - 36,5

CIS-2-butene - 7,7

TRANS-2-butene - 15,8

Isobutan - 1,2

C5and more heavy - 7,1

Got the catalyst with the following characteristics:

the molar ratio of SiO2/Al2O3- 892

the size of the crystals - 0,001 - 0,01 mm

specific surface 394 m2/g

Delta d-28oC - -

crystal structure - .. % monoclinic

Na2O - <500 wt. parts per million

K2O - <500 wt. parts per million

The results are presented in table 6. The transformation and the output was calculated as in example 1. In table 7 the outputs calculated for the different hydrocarbons in the first fraction, as was done in example 1.

Comparative example D

Example 4 was repeated, except that the processing operation silicalite ferry was omitted. Results are also presented in tables 6 and 7.

Examples 2 to 4 show that the steam treatment stabilizes the conversion of butenes and education Isobutanol. Not wishing to be bound by any theory, we nevertheless can assume that after the steam treatment, the pores are blocked Levinov, which consists in passing a feedstock containing n-butene over silicalite using steam, characterized in that the method comprises passing steam, pure or diluted with an inert gas, over silicalite at a temperature of from 300 to 750oC, the material containing at least 10 vol.% n-butene and possibly isobutene, with a maximum ratio of isobutene to n-butene 1 : 2, the deletion of this material over silicalite at a temperature of at least 500oC and the extract stream containing an increased amount of isobutene.

2. The method according to p. 1, characterized in that steam is passed over silicalite at a temperature of from 450 to 600oC.

3. The method according to p. 1 or 2, characterized in that the vapor is diluted with an inert gas in a ratio of from 1 : 99 to 99 : 1.

4. The method according to PP.1 to 3, characterized in that steam is passed over silicalite for at least 24 hours, preferably within 72 hours

5. The method according to PP.1 to 4, characterized in that the steam is passed over silicalite with a bulk velocity component from 1 to 100, preferably about 10 ml water per ml silicalite per hour.

6. The method according to PP.1 to 5, characterized in that it further includes the operations Department neproreagirovavshimi hydrocarbons in raw materials.

7. The method according to PP.1 - 6, characterized in that use extruded polymorphic silicalite catalyst consisting essentially of silicalite.

8. The method according to p. 7, characterized in that steam is passed over silicalite before extrusion.

9. The method according to PP.1 to 8, characterized in that it is used for the selective isomerization of n-butenes to isobutene.

 

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