Method for catalytic dehydrogenation of hydrocarbons

 

(57) Abstract:

Usage: petrochemistry. Essence: carry out the catalytic dehydrogenation of hydrocarbons comprising passing the reaction gas mixture through the catalyst bed at a temperature of 400-800oWith, the supply of heat to the endothermic reaction zone is performed by filtering the dispersed solid heat carrier heated to 400-800oWith, through the fixed catalyst bed, thus filtering the reaction gas mixture and solid dispersion carrier is carried out in one direction from top to bottom. In the process using any catalyst capable of conducting the dehydrogenation, for example CR2ABOUT3- (Na)-Al2ABOUT3, PT-Sn/Al2ABOUT3, PT-In/Al2ABOUT3, PT-Sn-K/Al2ABOUT3, PT-Sn/ZnAl2ABOUT4Pt-In/ZnAl2ABOUT4, Fe2ABOUT3-K2On the other, the process is carried out at flow rate of gas 200-1500 h-1. Use the catalyst in the form of rings, balls, pellets, mini-blocks, blocks cell structure, equivalent to the diameter of which exceeds 4 mm, the Technical result: increased time to perform the reaction while maintaining a high degree of conversion of the starting materials. 14 C. p. F.-ly, 1 table.

In recent years, the world is continuously growing interest in the processes of dehydrogenation of light hydrocarbons. This is due to continuously increasing demand for olefins and diolefins hydrocarbons (propylene, n-butenes, isobutylene, butadiene, isoprene, styrene and its derivatives), which find wide application in various chemical industries for production of synthetic rubbers (SK), plastics, components of motor fuels (MTBE, MTAA, alkylates) and other valuable chemical products. All this stimulates the development of new, more efficient processes of dehydrogenation and catalyst.

There are a number of features of reactions of dehydrogenation, largely determine not only the choice of conditions and the technological design process, but also the nature of the used catalyst. Thus, the reaction of dehydrogenation of paraffins and olefins highly endothermic, and the yields of the target products are limited by the equilibrium of the reaction. Acceptable yields of the target products in the dehydrogenation of paraffins is achieved only at temperatures above 520oC and dehydrogenation of olefins above 570oC. For this reason processeur flow processes of cracking and coke deposition on the catalyst surface. Especially not favorable thermodynamic characteristics for the dehydrogenation of olefins and benzene. For the purpose of lowering the partial pressure of the source of hydrocarbons and increasing yields of the target products of the processes carried out at the dilution of raw water vapor, which, moreover, is cooled. The dehydrogenation of paraffins is carried out at pressures close to atmospheric or under vacuum.

Currently, the industry uses four main technological options processes dehydrogenation of lower paraffins.

Is the process "Catofin" (ABB Lummus Crest/United Catalysts) is carried out in a vacuum adiabatic reactors with a stationary layer alimohammadi catalyst. The heat generated during the regeneration of the catalyst from the carbon deposits, is used for the endothermic dehydrogenation reaction (U.S. patent N 4581339, B 01 J 38/12, 8.04.1986). Therefore, the process is executed short cycles (15-25 minutes) dehydrogenation - regeneration, which requires a large number of reactors for the continuous operation of the process.

Is the process "FFB - Fluidized Bed Dehydrogenation" (Snamprogetti - Yarsintez) is carried out in a fluidized bed reactor (Kotelnikov G. R. React. Kinet. Catal. Lett. 1995. V. 55. N. 2. the tent of the Russian Federation N 2156161. C 07 C 5/333, 31.03.1999) alimohammadi catalyst (catalyst PCA). The catalyst circulates between the reactor and the regenerator, the heat of the burning coke is used for carrying out endothermic reactions. Thus, the catalyst also functions as a coolant. The catalyst used in this process must meet certain requirements, including resistance to mechanical stress, resulting from its motion. Despite a well-established technology in the fluidized bed, which option has the lowest capital cost, this method has a significant drawback due to the use of environmentally hazardous catalyst. In the catalyst composition includes hexavalent chromium, also known as a carcinogenic substance.

The process Oleflex by UOP (USA) is carried out at atmospheric pressure with the ball moving bed of platinum catalyst in a multistage reactor site along the contour of the reactor-regenerator with an intermediate heat supply between steps (U.S. patent N 4663493, C 07 C 5/333, 5.05.1987; N 4430517, C 07 C 5/333, 7.02.1984). The initial mixture is diluted with hydrogen to reduce coke formation. To obtain the degree of transformation aetsa high capital costs due to the complex hardware design. In addition, this technology places high demands on the mechanical strength of the catalyst.

The process of STAR company Phillips Petroleum Co. carried out at elevated pressure in an isothermal reactor with a fixed catalyst bed. A catalyst comprising a platinum coated on spinel placed in the tubes, the heated flue gases, work cycles for 7-8 hours with the regeneration of 1 hour. The initial reaction mixture is diluted with water vapor in the ratio (in moles) in the range of from 1/1 to 1/25 and hydrogen from 0.3/1 to 1.3/1 (Argentine polybutenes producer installing dehydro unit. Oil and Gas J. , 1994, Vol. 92, Iss. 17, S. 50-51, ISSN 0030-1388; U.S. patent N 3670044, B 01 J 11/12, 13/06/1972; N 3894110, C 07 C 5/18, 8.07.1975; N 4229609, C 07 C 5/36, 21.10.1980; N 4926005, C 07 C 15.05.1990).

In addition, there are new technological developments aimed at addressing the problem of supplying additional heat to the reaction zone. For example, the process for conversion of hydrocarbons, in which an additional supply of heat in the reaction zone is carried out using an inert particles (U.S. patent N 5030338, C 10 G 35/095, 9.11.1988). The catalyst and inert particles are mixed and fed into the reactor with a fluidized bed. Inert heated to a higher temperature, gives off heat to the catalyst, thereby compensating for pegrev, as a catalyst for regeneration under more mild conditions.

The closest is a method of dehydrogenation of acyclic hydrocarbons, (ed. St. USSR N 1511894, B 01 J 23/60, 1.06.1989). The process is carried out at atmospheric pressure in a stationary layer of a catalyst which contains platinum, modified additives tin, aluminium spinel and represents granules 2,2 - 3,0 mm as a source of raw material use n-butane, isobutane, isopentane, diluted with hydrogen and steam in a molar ratio of 1: 0,8: 8. The dehydrogenation is carried out at a temperature of 550 - 590oC short 15-minute alternating cycles of dehydrogenation - regeneration. Supplied with heated feedstock not enough heat for a longer endothermic dehydrogenation reaction.

Task to be solved by the present invention is directed, is to develop a process of dehydrogenation in a stationary layer with long meregenerasikan period of operation of the catalyst, while maintaining high yields of the target product.

The problem is solved by a method of catalytic dehydrogenation of hydrocarbons comprising passing the reaction gas mixture through the catalyst bed at tverdogo coolant, heated to 400 - 800oC, through the fixed catalyst bed, thus filtering the solid dispersion carrier is carried out in one direction from top to bottom, which is the preferred carrying out of the way.

As a filterable solid carrier is used as the inert material, and the material with catalytic activity in the main reaction process, and/or sorption properties with respect to the original substances, and/or the reaction products with a particle size of not less than 40 μm, the heat capacity of not less than 0,65 j/grad.

In the process using any catalyst capable of conducting the dehydrogenation: Cr2O3-K(Na)-Al2O3Pt-Sn/Al2O3Pt-In/Al2O3Pt-Sn-K/Al2O3Pt-Sn/ZnAl2O4Pt-In/ZnAl2O4, Fe2O3-K2O and the other, while the process is conducted at a volumetric rate of gas - 200 - 1500 h-1. Use the catalyst in the form of rings, balls, pellets, mini-blocks, blocks cell structure, the equivalent diameter exceeding 4 mm

Above the layer of catalyst is placed a layer of inert nozzle height no more than the diameter of the reactor. If necessary, carry S="ptx2">

The reaction gas mixture consists only of hydrocarbons from hydrocarbons and hydrogen from hydrocarbons and water vapor, hydrocarbons, hydrogen, and water vapor.

As hydrocarbons are using propane, n-butane, isobutane, n-butenes, isopentane, isoamylene, ethylbenzene.

To increase the time of carrying out the dehydrogenation reaction is possible in the proposed version of the dehydrogenation circulating through the catalyst heated fine particulate heat carrier, inert or possessing catalytic properties. The heated particles of the fluid being filtered by the voids between the granules of the catalyst, is heated as a catalyst, and the gaseous reaction mixture to the reaction temperature and allow you to draw additional heat to the endothermic reaction zone. Since the major portion of the heat supplied by the heat carrier, it is possible to reduce the dilution of the raw water vapor, which should lead to lower energy process.

Additional differences between the proposed method:

use solid dispersion carrier with a particle size of not less than 40 μm, the heat capacity of not less than 0,65 j/grad coming to the endothermic reaction zone heated UB>2O3Pt-Sn/Al2O3Pt-In/Al2O3Pt-Sn-K/Al2O3Pt-Sn/ZnAl2O4Pt-In/ZnAl2O4, Fe2O3-K2O and others in the form of rings, balls, pellets, mini-blocks, blocks cell structure,

using the catalyst, the equivalent diameter of which exceeds 4 mm,

above the layer of catalyst is placed a layer of inert nozzle height no more than the diameter of the reactor,

the process is conducted at a volumetric rate of gas - 200 - 1500 h-1,

in the case of reducing the activity of the catalyst regeneration carry oxygen-containing mixture by filtration of the solid flow rate through the catalyst bed,

the reaction gas mixture consists of: (a) only from hydrocarbons; b) from hydrocarbons and hydrogen; b) from hydrocarbons and water vapor; d) from hydrocarbons, hydrogen and water vapor,

as hydrocarbons are using propane, n-butane, isobutane, n-butenes, isopentane, isoamylene, ethylbenzene.

The invention is illustrated by the following examples.

Example 1. The process is performed on the catalytic installation dehydrogenation of hydrocarbons, comprising a reactor with a diameter of 32 mm, quartz heater, a hopper for feeding the dispersed Agregat 50 cm3catalyst in the form of balls with a size of 5.5 mm, the Catalyst has the composition: 0,75 wt. % Pt, 0.5 wt. % Sn on the media-Al2O3. The catalyst layer porosity of 0.4. The reaction mixture has an initial composition (in moles) isobutane: hydrogen = 1: 1, the volumetric flow rate of isobutane 600 h-1. As a solid dispersion carrier is an inert material-Al2O3faction 0,08 - 0,16 mm, the heat capacity of 0.77 j/grad. The amount of coolant required to supply heat to the reaction zone, calculated on the basis of heat balance and is in this case 1.7 g/C. the Coolant and the reaction mixture pass through a quartz heater, where it is mixed and heated to the desired temperature. From the heater the mixture enters the reactor, which moves in one direction from top to bottom and interacts with a fixed catalyst bed. The temperature at the inlet of the reactor - 600oC, at the exit of the reactor 550oC. a Portion of the exit stream is directed for chromatographic analysis. The time of reaction is one hour. During the experiment, the catalyst retains a constant activity. The degree of transformation of the initial isobutane catalyst is 49.8%, selectivity SOC 1, but the catalyst has the composition: 0.2 wt. % Pt, 0.7 wt. % Sn on ZnAl2O4. The initial reaction mixture composition Bhutan : hydrogen : steam = 1: 1: 5 served with a bulk velocity of Bhutan 600 h-1. As a solid carrier is used quartz sand fraction of 0.10 - 0.25 mm, the heat capacity of 0.74 j/grad. The amount of the heated dispersion of the coolant supplied into the reaction zone, which in this case is 1.8 g/C. the Degree of conversion and selectivity are shown in table.

Example 3. Analogously to example 1, but the catalyst of the same chemical composition is in the form of rings of size HH,5. The number of dispersed fluid - 1.3 g/C. the Degree of conversion and selectivity are shown in table.

Example 4. Analogously to example 1, but the initial mixture consists of isobutane and served with a bulk velocity of 450 h-1. Catalyst Cr2O3/ Al2O3has the form of balls size 5 mm, the Flow of heated coolant - 1.4 g/C. the Degree of conversion and selectivity are shown in table. The catalyst does not lose activity within 30 minutes. Further, the catalyst activity begins to decline, therefore, conduct its regeneration by combustion of coke. Regeneration is carried out for 30 mi the of oxygen in the mixture is from 5 to 20%. Heat due to the heat accumulates filterable inert heat carrier, which is collected in a container. After accumulation of dispersed material fed into the hopper coolant and is used to supply heat to the reaction zone.

Example 5. Analogously to example 1, but above the layer of catalyst is placed 25 cm3-Al2O3the tip height 31 mm, inert in the process, having the same size and shape as the catalyst. The source gas mixture of isobutane : hydrogen = 1 : 1 served at a temperature of 20oC directly into the reactor, where the layer of inert material is mixed with cooled and heated to the temperature at which the reaction is carried out dehydrogenation - 600oC. to ensure That the temperature of the catalyst layer 600oC, solid fluid when passing through a quartz heater or heated to 630oC, the amount of solid carrier is 1.2 g/s, or increase the amount of the heat carrier heated to 600oC, up to 2.0 g/C. the Degree of conversion and selectivity are shown in table.

Example 6. Analogously to example 1, but instead of use isobutane n-butenes. Charged to the reactor ball catalyst containing 10 wt.%. KFeO<2O = 1: 10, the volumetric feed rate of n-butenes - 400 h-1. The inlet temperature in the reactor 620oC, at the exit of the reactor 580oC. the Number of dispersed fluid, necessary for the supply of heat in the reaction zone is 0.9 g/C. the Degree of conversion and selectivity are shown in table.

Example 7. Analogously to example 1, but instead of inert material-Al2O3use coolant with catalytic activity - 10% wt. KFeO2on the media-Al2O3the fraction 0,08 - 0,16 mm as a fixed catalyst layer using 10% wt. KFeO2on-Al2O3in the form of balls with a size of 5.5 mm, the Reaction mixture has an initial composition (in moles) C4H8: H2O = 1: 10, the volumetric feed rate of n-butenes - 400 h-1. The inlet temperature in the reactor 620oC, at the exit of the reactor 580oC. the Number of dispersed fluid, necessary for the supply of heat in the reaction zone is 1.0 g/C. the Degree of conversion and selectivity are shown in table.

Example 8. Analogously to example 1, but fine circulates in a closed circuit. The heated coolant along with the original reaction mixture flows in reacto the ü the reaction products and the coolant fed into the cyclone where is their separation, and then the dispersed material is mixed with a fresh portion of the source gas mixture is recycled to the heater. Charged to the reactor 180 cm3of the catalyst. The volumetric flow rate of isobutane -1200 h-1. The number of dispersed fluid - 12,1 g/C. the Degree of conversion and selectivity are shown in table.

As seen from the above examples, the proposed method can improve the time of carrying out the reaction while maintaining a high degree of transformation of the original substances and can find industrial application in the processes of dehydrogenation of hydrocarbons.

1. Method for catalytic dehydrogenation of hydrocarbons comprising passing the reaction mixture through the catalyst layer, characterized in that the dehydrogenation is carried out at a temperature of 400-800oWith and supply heat to the endothermic reaction zone is performed by filtering the solid dispersion of the coolant heated up to 400-800oWith, through the fixed catalyst bed.

2. The method according to p. 1, wherein filtering the reaction gas mixture and solid dispersion carrier is carried out in one direction from top to bottom.

3. The method according to PP. 1 and 2, characterized because catalytic activity in the main reaction process and/or sorption properties with respect to the original substances and/or products of reaction.

4. The method according to PP. 1-3, characterized in that use solid dispersion carrier with a particle size of not less than 40 μm, the heat capacity of not less than 0,65 j/grad.

5. The method according to PP. 1-4, characterized in that the use of any catalyst capable of conducting the dehydration, in particular CR2ABOUT3- (Na)-Al2ABOUT3, PT-Sn/Al2ABOUT3, PT-In/Al2ABOUT3, PT-Sn-K/Al2ABOUT3, PT-Sn/ZnAl2ABOUT4Pt-In/ZnAl2ABOUT4,

Fe2ABOUT3-K2O.

6. The method according to PP. 1-5, characterized in that the process is conducted at a volumetric rate of gas 200-1500 h-1.

7. The method according to PP. 1-6, characterized in that the use of the catalyst in the form of rings, beads, granules, mini-blocks, blocks cell structure.

8. The method according to PP. 1-7, characterized in that the used catalyst, the equivalent diameter exceeding 4 mm

9. The method according to PP. 1-8, characterized in that the catalyst bed is placed a layer of inert nozzle height no more than the diameter of the reactor.

10. The method according to PP. 1-9, characterized in that the regeneration of the catalyst to carry out oxygen-containing mixture by filtration of the solid flow rate through the catalyst bed.

11. The method according to the March. 1-10, characterized in that the reaction gas mixture comprises hydrocarbons and hydrogen.

13. The method according to PP. 1-10, characterized in that the reaction gas mixture consists of hydrocarbons and water vapor.

14. The method according to PP. 1-10, characterized in that the reaction gas mixture consists of hydrocarbons, hydrogen and water vapor.

15. The method according to PP. 1-14, characterized in that hydrocarbons are using propane, n-butane, isobutane, n-butenes, isopentane, isoamylene, ethylbenzene.

 

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EFFECT: enhanced isoprene production efficiency and reduced specific consumption of raw materials.

1 dwg, 5 ex

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