RU2619128C1 - Method for obtaining olefin c3-c5 carbohydrates - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to method for producing olefinic C₃-C₅ hydrocarbons by dehydrogenation of the corresponding paraffinic hydrocarbons in fluidized bed of aluminium-chromium catalyst circulating in the system including the reactor, regenerator (13), and reduction-desorption catalytic preparation after the regenerator (13) carried out by treating the catalyst with reducing gas in a countercurrent mode using horizontal sectioning grids (2). The method is characterized in that immediately after regenerator (13), treatment is carried out in directed internal catalyst circulation mode using vertical partition (6) separating fluidized bed into lifting section (14) and pressure section (15), and then in countercurrent mode with at ratio of catalyst residence time in the said modes is 0.3-3.0.

EFFECT: increasing the yields of target product.

7 cl, 4 ex, 1 tbl

Description

The present invention relates to the field of petrochemistry, in particular to a method for producing olefin hydrocarbons, which are used in the future to obtain the main monomers of SC, as well as in the production of polypropylene, methyl tertiary butyl ether, etc.

A known method of producing olefin hydrocarbons by dehydrogenation of the corresponding paraffin hydrocarbons in a reactor-regenerator system with a moving coarse-grained catalyst (Y. Ya. Kirnos, O. B. Litvin, “Modern industrial methods for the synthesis of butadiene.” Analytical comparative reviews CNIITENeftekhim, series “Production of synthetic rubbers” , M., 1967, p. 81).

The disadvantage of this method is the complex hardware design of the reactor unit and the inability to create large capacity plants due to the difficulties in organizing the circulation of coarse catalyst in the reactor-regenerator system.

A known method for producing light olefins (patent RU 2125079, IPC C10G 11/18, B01J 8/18, publ. 01/20/1999), which includes the stage of supplying the hydrocarbon starting material to the reaction zone containing the solid catalyst, contacting the hydrocarbon starting material in the reaction zone with a catalyst, under conditions that favor the catalytic conversion of hydrocarbons to light olefins, separation of the reaction products from the reaction zone after catalytic conversion, catalyst separation and deactivation regeneration Foot of catalyst in the regenerator. In accordance with the invention, the hydrocarbon feed is contacted with the catalyst in a circulating fluidized bed reactor with a residence time in the range of 0.1 to 3 seconds.

The proposed method does not allow to achieve industrially significant indicators of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons: reactor productivity, olefin yields on the passed and decomposed raw materials.

The closest in technical essence and the achieved result is a method for producing olefin hydrocarbons by dehydrogenation of the corresponding paraffin hydrocarbons, carried out in a fluidized bed system of a fine-grained alumina-chromium catalyst containing a reactor, regenerator and a unit for the recovery and desorption preparation of the regenerated catalyst with catalyst circulation between them (R.K. Mikhailov, AN Bushin, I.Ya. Tyuryaev, SM Khripina "Preparation of the catalyst for the dehydrogenation of paraffin carbohydrates Orodov ”, Scientific and Technical Collection“ Synthetic Rubber Industry ”, TsNIITE-Neftekhim, M., 1969, No. 4, p. 3-6).

According to this method, the recovery-desorption preparation of the regenerated catalyst before it is fed to the reactor is carried out by treating the catalyst with a reducing gas in the countercurrent mode of the catalyst and gas using horizontal type sectional gratings of the failure type in the preparation unit.

The specified method does not achieve a sufficiently deep degree of recovery (preparation) of the catalyst due to the low rate of mass transfer processes in the used method of contacting the catalyst and gas with a short contact time, low linear gas velocities in the preparation unit, limited by the design of the dehydrogenation system. All this leads to a decrease in the yields of the target product in the dehydrogenation processes.

The objective of the present invention is to increase the yields of the target product in the dehydrogenation of paraffin hydrocarbons in a fluidized bed of chromium-chromium catalysts by increasing the degree of catalyst recovery.

A method for producing C ₃ -C ₅ olefin hydrocarbons by dehydrogenating the corresponding paraffin hydrocarbons in a fluidized bed of an aluminum-chromium catalyst circulating in a system including a reactor, a regenerator 13, and a catalyst recovery and desorption preparation unit after the regenerator 13 is proposed.

This preparation is carried out by treating the catalyst with a reducing gas in countercurrent mode using horizontal sectional gratings 2. Moreover, immediately after the regenerator 13, the treatment is carried out in the direction of the internal circulation of the catalyst using a vertical partition 6 separating the fluidized bed into the lifting 14 and pressure sections 15, and then - in countercurrent mode with a ratio of the residence time of the catalyst in these modes, equal to 0.3-3.0.

The vertical partition 6 can be made in the form of a cylindrical pipe.

The vertical partition 6 can be installed in the upper part of the glass-reducing agent 1, built into the lower part of the regenerator 13.

The vertical partition 6 may be a continuation of the upper part of the glass-reducing agent 8, which is included in the lower part of the housing of the regenerator 13.

In the vertical partition (6), the holes (11) for the catalyst overflow can be made in the form of a circle.

To create internal circulation of the catalyst, air, natural gas, and nitrogen can be supplied to the sections.

Preferably, the linear gas velocity in the lifting section 14 is higher than in the pressure section 15.

A method for producing C ₃ -C ₅ olefin hydrocarbons by dehydrogenating the corresponding paraffin hydrocarbons in a fluidized bed of an aluminum-chromium catalyst circulating in a system including a reactor, a regenerator, and a catalyst recovery and desorption preparation unit after the regenerator is proposed.

This preparation is carried out by treating the catalyst with a reducing gas in countercurrent mode using horizontal sectional gratings. Moreover, immediately after the regenerator, the treatment is carried out in the directional internal circulation of the catalyst using a vertical partition dividing the fluidized bed into the lifting and pressure sections, and then in countercurrent mode.

Hydrogen-containing gases, CO, C ₁ -C ₅ hydrocarbons and mixtures thereof can be used as a reducing gas.

For the organization of the modes indicated in the present invention, various design solutions can be used.

Possible schematics of the catalyst recovery and desorption unit are shown in FIG. 1 and FIG. 2. In accordance with the proposed claims, there may be other node schemes. The preparation of FIG. 1 is carried out in a reducing glass 1, which is integrated in the lower part of the regenerator 13. The reducing glass 1 is partitioned in height by sectional sectional gratings 2. The reducing gas is supplied through the bubbler 3 to the lower part of the reducing glass 1. Nitrogen is supplied through a bubbler 4 located below the bubbler 3.

To carry out the process in accordance with the invention, a circulation pipe 6 is installed under the bubbler 5 for supplying air to the regenerator 13 in the upper part of the reducing cup 1, into which nitrogen is supplied to ensure catalyst recirculation in the upper part of the reducing cup 1. As can be seen from FIG. 1, the space between the bubbler 5 for supplying air to the regenerator and the partitioning grid 7, located under the lower end of the circulation pipe 6, is the first catalyst preparation stage operating in the directional internal circulation mode. The space between the partition lattice 7 and the bubbler for supplying nitrogen 4 in the lower part of the reducing glass 1 represents the second stage of preparation of the catalyst, operating in countercurrent mode of the catalyst and gas. The catalyst circulating from the regenerator 13 to the reactor passes sequentially through the first and second stages of contacting with the reducing gas and nitrogen supplied to the reducing glass 1, undergoing reduction-desorption preparation.

The preparation of the catalyst according to FIG. 2 is carried out in a reducing cup 8 integrated in the regenerator 13 in such a way that the upper part of the reducing cup 8 enters the lower part of the regenerator body, while the upper end 9 of the reducing cup 8 is located under the bubbler 10 for supplying air to the regenerator, although it may located above the bubbler 10 depending on the implementation scheme of the method.

To carry out the process in accordance with the invention, in the casing of the upper part of the reducing glass, in the region located inside the regenerator body, there are openings 11 for the catalyst overflow. A bubbler 12 is located in the cavity of the conical bottom of the regenerator at a level below the holes for the catalyst overflow to supply gas to liquefy the catalyst. In this case, an intense directional internal circulation of the catalyst occurs in the zone between the holes for the catalyst flow and the bubbler 10 of air supply to the regenerator. The specified zone is the first stage of the catalyst preparation unit located above the second preparation stage in the lower part of the reducing glass 8.

Thus, for the implementation of the directed internal circulation of the catalyst in a fluidized bed, a vertical partition can be arranged in the latter, dividing the fluidized bed into a lift 14 and a pressure section 15. The partition can be flat, cylindrical, in the form of a pipe 6 or other shape. In its lower part, the baffle may have openings 11 for the catalyst overflow with its internal (in the area of the baffle location) circulation of the catalyst.

To ensure the circulation of the catalyst, the linear velocity of the gas supplied to the lifting section 14 should be higher than in the pressure section 15. Moreover, the concentration of the catalyst and, accordingly, the hydrostatic pressure of the catalyst layer in the lifting section 14 will be lower than the pressure section 15, which ensures an intense internal directed circulation of the catalyst, in which the catalyst rises in the lifting section 14 and lowers in the pressure section 15.

To implement the counterflow regime of the catalyst and the reducing gas, horizontal sectional gratings of a failure type with a live cross section can be used, providing countercurrent movement of the catalyst and gas in the holes of the gratings. Lattices can be, for example, with openings in the form of slots and made of corners, pipes, inclined at an angle to the direction of gas flow of flat plates, etc.

The organization at the initial stage of preparation of the aluminum-chromium catalyst of an additional stage of preparation operating in the directed internal circulation of the catalyst allows to increase the degree of recovery (preparation) of the catalyst, as well as to reduce the consumption of reducing gas supplied to the preparation of the catalyst due to:

- increased mass transfer in the volume of the specified stage with intense internal circulation of the catalyst;

- repeated recirculation of the catalyst through the volume of the specified stage;

- increasing the residence time of the catalyst with increasing concentration of the latter in the volume of the specified stage due to the intensive directional circulation, as well as in connection with the possibility of increasing the volume of this stage due to the increase in the cross section (diameter) of the stage;

- more "softer" conduct of the recovery process during the implementation of the two-stage method of preparing the catalyst with the redistribution of the conversion of the reducing gas in stages.

An increase in the degree of reduction of a catalyst containing chromium oxides of variable valency when preparing a regenerated (oxidized) catalyst before feeding it into the reactor reduces the amount of hexavalent metal oxide (CrO ₃ type) entering the reactor with the circulating catalyst. Considering that hexavalent metal oxide (CrO ₃ ) in the reducing medium of the reactor is converted to trivalent metal oxide (type Cr ₂ O ₃ ) with the formation of water vapor, which is poison for the catalyst, an increase in the degree of catalyst reduction in the reduction and desorption unit leads to an increase dehydrogenation indicators.

When the ratio of the residence time of the catalyst in the steps of the recovery-desorption preparation unit is less than 0.3, the influence of the additional stage with directed internal circulation of the catalyst on the improvement of the performance of the preparation unit as a whole and, accordingly, on the improvement of the dehydrogenation performance is no longer noticeable, and with more than 3, a situation of deterioration of the performance of the preparation unit and, accordingly, dehydrogenation indicators.

The technical result consists in increasing the yields of the target product - olefins.

The invention is illustrated by the following examples.

Example 1

The dehydrogenation of n-butane to butylenes is carried out in a unit with a fluidized bed of an aluminum-chromium catalyst containing Cr ₂ O ₃ - 14 wt. %, K ₂ O - 3 wt. %, SiO ₂ - 9 wt. % and Al ₂ O ₃ - 74 wt. % The installation consists of a reactor and a regenerator with continuous circulation of the catalyst. A diagram of the reductive-desorption catalyst preparation unit is shown in FIG. 1. In the lower part of the reducing glass 1 through a bubbler 3, natural gas (methane content ~ 97 wt.%) In the amount of 15 nm ³ / h is supplied as a reducing gas (which corresponds to a volumetric feed rate of ~ 120 h ^-1 ). Nitrogen is supplied through a bubbler 4 located below the bubbler 3 in an amount of ~ 10 nm ³ / h (which corresponds to a volumetric feed rate of ~ 70 h ^-1 ). The process is carried out at a temperature in the reactor of 585 ° C and a regenerator of 650 ° C. 480 kg / h of n-butane are fed to the reactor. The circulation of the catalyst in the reactor-regenerator system through the cup-reducing agent 1 is 7.2 t / h. The residence time of the catalyst in the reducing glass 1 is 1.7-1.9 minutes. ~ 5 nm ³ / h of nitrogen is fed into the circulation pipe 6 to recirculate the catalyst in the upper part of the reducing glass 1.

Data on other conditions of the process and indicators of dehydrogenation are given in table. 1. The results of dehydrogenation of n-butane under similar conditions according to the prototype are also presented there.

Example 2

The dehydrogenation of isobutane to isobutylene is carried out on a catalyst containing Cr ₂ O ₃ - 20 wt. %, K ₂ O - 2 wt. %, SiO ₂ - 2 wt. % and Al ₂ O ₃ - 76 wt. %, similarly to example 1, however, the dehydrogenation temperature is 580 ° C, and the regeneration is 650 ° C. The circulation of the catalyst between the reactor and the regenerator is 6.9 t / h, the supply of isobutane is 450 kg / h. A diagram of the unit for the recovery-desorption preparation of the regenerated catalyst before being fed to the reactor is shown in FIG. 2.

To carry out the process in accordance with the invention in a bubbler 12 for supplying gas to liquefy the catalyst. As a reducing gas serves natural gas in an amount of 5 nm ³ / h

Data on other conditions and indicators of dehydrogenation are given in table. 1. The results of dehydrogenation of isobutane under similar conditions according to the prototype are also presented there.

Example 3

The dehydrogenation of propane to propylene is carried out on a catalyst similar to that used in example 2 using a reductive-desorption catalyst preparation unit according to the same example. The propane dehydrogenation temperature is 590 ° С, the regeneration temperature is 650 ° С, the catalyst circulation between the reactor and the regenerator is 5.8 t / h, and the propane supply is 400 kg / h.

Data on other conditions and indicators of dehydrogenation are given in table. 1. The results of dehydrogenation of propane in similar conditions according to the prototype are also presented there.

Example 4

Isopentane dehydrogenation is carried out on a catalyst similar to that used in example 1 using a reductive-desorption catalyst preparation unit according to the same example. The isopentane dehydrogenation temperature is 575 ° С, and the regeneration temperature is 650 ° С, the catalyst circulation between the reactor and the regenerator is 7.2 t / h, the isopentane feed is 480 kg / h.

Data on other conditions and indicators of dehydrogenation are given in table. 1. The results of dehydrogenation of isopentane under similar conditions according to the prototype are also presented there.

As can be seen from the above examples, the proposed method allows to increase the yields of olefins in the dehydrogenation processes of paraffin hydrocarbons.

Claims (7)

1. A method for producing C ₃ -C ₅ olefin hydrocarbons by dehydrogenating the corresponding paraffin hydrocarbons in a fluidized bed of an aluminum-chromium catalyst circulating in a system including a reactor, a regenerator (13) and a catalyst recovery-desorption unit after the regenerator (13), which is carried out by treating the catalyst with gas -reducer in countercurrent mode using horizontal sectioning gratings (2), characterized in that immediately after the regenerator (13) the processing is carried out in the directional mode internal circulation of the catalyst using a vertical partition (6) dividing the fluidized bed into the lifting (14) and pressure (15) sections, and then in counterflow mode with a ratio of the residence time of the catalyst in these modes equal to 0.3-3.0 . 2. The method according to p. 1, characterized in that the vertical partition (6) is made in the form of a cylindrical pipe. 3. The method according to p. 2, characterized in that the vertical partition (6) is installed in the upper part of the glass-reducing agent (1), integrated in the lower part of the regenerator (13). 4. The method according to p. 2, characterized in that the vertical partition (6) is a continuation of the upper part of the recovery glass (8), which is included in the lower part of the regenerator body (13). 5. The method according to p. 1, characterized in that in the vertical partition (6) perform holes (11) for the flow of catalyst in the form of a circle. 6. The method according to p. 1, characterized in that to create an internal circulation of the catalyst in the section serves air, natural gas, nitrogen. 7. The method according to any one of paragraphs. 1-6, characterized in that the linear gas velocity in the lifting section (14) is higher than in the pressure section (15).

Images