Catalyst for dehydrogenation of hydrocarbons and method thereof


 

(57) Abstract:

Describes a catalyst for the dehydrogenation of carbohydrates C2- C5hydrocarbons containing oxides of aluminum, chromium, a compound modifier metal, alkaline and/or alkaline earth metal, characterized in that it additionally contains compounds of silicon and/or boron, as a modifier metal contains at least one compound from the group of zirconium, titanium, iron, gallium, cobalt, molybdenum, manganese, tin, and the catalyst formed during the heat treatment of aluminum compounds of the formula Al2O3n H2O, where n = 0.3 to 1.5, in conjunction with the compounds of the above elements, and has the following composition, wt.% (in terms of oxide): oxide of chromium calculated as Cr2O312 - 23; the connection of reactive metal from the group of Zr, Ti, Fe, Ga, Co, Sn, Mo, Mn of 0.1 to 1.5; a compound of silicon and/or boron 0,1 - 10,0; connection alkaline and/or alkaline earth metal of 0.5 - 3.5; aluminium oxide - rest. The catalyst has a value of specific surface area of 50 to 150 m2/g and a pore volume of 0.15 - 0.4 cm3/g, a particle size of 40 to 200 μm. Also described is a method of obtaining a catalyst. Technical result - receiving catalyst from polysensitization for dehydrogenation of paraffin hydrocarbons, in particular, for the dehydrogenation of C2-C5paraffins to the corresponding olefins.

Olefins are one of the most important products of organic synthesis. They are used in the production of polypropylene, synthetic rubber, high-octane gasoline antiknock additives and a variety of other industries.

One of the ways to obtain olefins is the dehydrogenation of paraffins. It is well known that from a thermodynamic point of view, the dehydrogenation of hydrocarbons, C2-C5not related to the number of effective processes. Since the reaction of dehydrogenation of indetermine, to achieve technically acceptable conversion of raw materials to the required temperature of 500-600oC. However, at these temperatures with a noticeable speed of flow and the adverse reactions of cracking and isomerization. This is because the carbon-carbon (C-C) bond is significantly less strong than the bond carbon-hydrogen (C-H). Therefore, the catalyst in the dehydrogenation process should guide the process energetically unfavorable ways, i.e. allow to carry out the process at low temperatures, and the reaction rate of cracking is possible to do the minimum. It must minimize the inevitable OBRAZOVANIYa must provide a high selectivity to the desired olefin decreasing isomerization, adverse reactions leading to coking. The formation of coke on the catalyst requires periodic regeneration of the latter at elevated temperatures, therefore, the catalyst must be stable. Special requirements to the mechanical strength of the catalyst, because the destruction of the problems of environmental pollution.

Available literature describes many catalytic compositions based on noble metals or combined with other elements.

The known method (Patent EP N 637578, IPC C 07 C 5/333, 1995) with a catalytic system containing gallium, platinum, possibly one or more alkaline or alkaline-earth metals and the media, which consists of alumina in Delta or theta phase or in a mixed Delta+theta or theta+alpha or Delta+theta+alpha phase, modified silicon oxide.

However, compositions containing precious metals, have increased kekirawa ability at elevated temperatures. This leads to rapid coking of the catalyst and loss of activity and, as a consequence, reduction of service life.

The disadvantage of the catalyst is relatively small prognostication dehydrogenation, most researchers concluded that effective catalysts for the dehydrogenation of C2-C5paraffins are chromium oxides supported on alumina and having high mechanical strength, although chrome compounds are harmful substance. Therefore, when creating new catalysts based on chromium compounds main task is durable fixation of chromium in the media, reducing wastewater when it is received, increased activity and stability.

Known catalyst containing the oxides of potassium, chromium, silicon, aluminum oxide (A. C. USSR N 1366200, IPC B 0 J 37/02, 23/26, 1988). The catalyst was prepared by impregnation of alumina previously calcined at 1000-1150oC, first solutions of chromium compounds and potassium, followed by drying, and then re-impregnated with a solution of silicon compounds, followed by drying and calcination.

The disadvantage of the catalyst and the method is the low mechanical strength and selectivity.

There is a method of cooking alimohammadi catalyst for dehydrogenation of paraffin hydrocarbons (RF Patent N 1736034, IPC B 01 J 37/02, 23/26, 21/04, 1995), which includes the calcination of aluminum hydroxide in vesvese-400oC, peptization aluminum hydroxide nitric acid with the simultaneous introduction of chromium and potassium compounds, forming by spray drying and calcination, the calcination under these conditions expose 50-80 wt.% aluminum hydroxide, the remaining 20-50 wt.% aluminum hydroxide calcined at 950-1200oC for 2-10 h

The catalyst is not sufficiently high activity and stability, low mechanical strength. The method of its production is complex and multi-stage. The molding of the catalyst is carried out at the stage spray drying.

A method of obtaining a catalyst dehydrogenation on the basis of Al, Cr, K and Si process for the dehydrogenation of C3-C5-paraffin hydrocarbons (Japan Patent N 7010350, IPC B 01 J 23/26, 1995), which includes processing annealing at 500-700oC aluminium oxide particles in the form of microspheres, processing, roasting at a temperature of > 1000oC for several hours, processing impregnation of the product of firing a solution containing compounds Cr and compounds K, processing, drying the resulting product, process, impregnation product drying a solution containing a compound of silicon and subsequent conduct are insufficient strength and stability, as well as the complexity and multi-stage process of obtaining.

The closest technical solution composition and method of preparation of the catalyst of the claimed catalyst is a catalyst for dehydrogenation of hydrocarbons (RF Patent N 1836140, IPC B 01 J 23/26, 21/06; C 07 C 5/333, 1993). The catalyst contains chromium oxide compound of alkali and/or alkaline earth metal and at least one connection of the modifying metal on the carrier is aluminum oxide as a compound modifier metal it contains the Zirconia in the following ratio, wt.%:

Oxide of chromium calculated as Cr2O3- 25

Connection alkaline and/or alkaline earth metal, calculated as oxide - 0,7 - 4,7

The Zirconia - 0,9

Media - Rest

For the preparation of the catalyst using a carrier - aluminum oxide in the form of tablets, impregnate the carrier with a solution containing compounds of chromium and zirconium, the impregnated product is dried in vacuum, and then conducting heat treatment at 740oC, then carry out the impregnation of the catalyst compound of the alkali or alkaline earth metal and the two-stage drying, first under vacuum and then in an atmosphere of air, zaa, reducing the formation of coke, but the lack of activity at a very high content of chromium oxide (25%) and complex manufacturing process.

The present invention is to obtain a catalyst with increased strength, activity and method of its production.

The problem is solved by a catalyst for the dehydrogenation of C2-C5hydrocarbons containing oxides of aluminum, chromium, a compound modifier metal, alkaline and/or alkaline earth metal, the catalyst additionally contains compounds of silicon and/or boron in an amount of 0.1-10%, as a modifier metal contains at least one compound from the group of zirconium, titanium, iron, gallium, cobalt, molybdenum, manganese, tin, and the catalyst formed during the heat treatment of aluminum compounds of the formula Al2O3n H2O, where n=0.3 to 1.5, in conjunction with the compounds of the above elements and has the following composition, wt.% (in terms of oxide):

Oxide of chromium calculated as Cr2O3- 12-23

The connection of reactive metal from the group of Zr, Ti, Fe, Ga, Co, Sn, Mo, Mn - 0,1-1,5

The compound of silicon and/or boron - 0,1-10,0

Connection alkaline and/or alkaline earth metal of 0.5-3.5

The aluminum oxide /g and a particle size of 40-200 μm.

The problem is solved by obtaining a catalyst for the dehydrogenation of C2-C5hydrocarbons, including impregnation of the carrier based on alumina with solutions of chromium compounds, alkaline and/or alkaline earth metal, the modifying metal, drying and annealing at 700-800oC, as the carrier is used as a compound of aluminium of the formula Al2O3n H2O, where n=0.3 to 1.5, as a compound modifier metal used is at least one compound from the group of zirconium, titanium, iron, gallium, cobalt, molybdenum, manganese, tin, and impose additional compounds of silicon and/or boron in an amount of 0.1-10% wt. the impregnation of the carrier, followed by drying and coating with other catalyst components or in conjunction with other components of the catalyst and the catalyst after calcination has the following composition, wt.% (in terms of oxide):

Oxide of chromium calculated as Cr2O3- 12-23

The connection of reactive metal from the group of Zr, Ti, Fe, Ga, Co, Mo, Mn, Sn - 0,1-1,5

The compound of silicon and/or boron - 0,1-10,0

Connection alkaline and/or alkaline earth metal of 0.5-3.5

Alumina - Rest

For the preparation of the catalyst stellitano structure or partly crystalline structure, obtained, for example, by the rapid dehydration of hydrargillite (applies to the catalyst).

The resulting catalyst has a specific surface area of 50-150 m2/g, pore volume of 0.15-0.4 cm2/,

Impregnation of the aluminum compounds of the formula Al2O3n H2O, where N=0.3 to 1.5, is carried out in an aqueous solution of compounds of silicon and/or boron with a pH of 6.5 - 12 and at a temperature of 70-100oC, followed by drying and placement of the remaining components on capacity or impregnate both compounds boron and/or silicon, alkaline and/or alkaline earth metal, chromium, modifying metal capacity at a temperature of 20-100oC. After impregnation the catalyst is dried in vacuum.

As boron compounds, use boric acid. As compounds of silicon using a Hydrosol of silicon, tetraethoxysilane.

In the known solution for the preparation of the catalyst using a carrier having formed a crystalline structure (-Al2O3and others), which cause repeated impregnation of the active components of the catalyst. For fixing these components on the media carry out the heat treatment in several stages. Nevertheless sufficiently durable sagrera is the ablation of the active component.

The proposed solution is the formation of the catalyst during the heat treatment of aluminum compounds of the formula Al2O3n H2O, where N = 0.3 to 1.5, preferably having an amorphous or logoutresultevent structure or partly crystalline structure, together with the active components of the catalyst, which leads to strong communication media with active components.

In addition, when the joint application of all components occurs simultaneous formation and modification of the carrier and the catalytic composition, which allows chemically dispersing the active components so that after heat treatment at 700 to 800oC compounds of chromium, potassium and modifying compounds are x-ray amorphous state, which can significantly increase the activity and selectivity of the catalyst.

The catalyst is prepared as follows.

For the preparation of the catalyst is used as a compound of aluminum with the gross formula Al2O3n H2O (n = 0.3 to 1.5). This compound can be obtained by any known means, for example, by the rapid dehydration of hydrargillite. While the preferred x-ray amorphous structure this refers to such x-ray analysis, which does not detect any lines, characteristic of any crystalline phase. Under semi-crystalline oxygen-containing compound of aluminum understand such analysis which detects the spectrum of the diffraction lines characteristic of crystalline phases at least one of the compounds: bayerite, hydro-argillite, boehmite, -, -, -, -, -, - Al2O3.

In the proposed method, the impregnation takes place simultaneously all the components of the catalyst or from a solution, or capacity. The preferred option is the method of applying for capacity, because there is no waste water containing harmful compounds chromium.

When the impregnation of the aluminum compounds connectors boron and/or silicon from the solution at a pH of 6.5 to 12 and a temperature of 70-100oC creates favorable conditions for the uniform distribution in the structure of the aluminum compounds of boron and/or silicon, which increases thermal stability of the catalyst. Drying captures the compound obtained aluminum, modified with boron and/or silicon. It allows you to separate in time and space processes of obtaining partially modified aluminum compounds and catalyst, which happens sometimes neophoca, the production ecology. In addition, when preparing the preformed catalyst this stage is necessary because they received a modified connection of the aluminum is in this case the binder.

In the case of the preparation of the preformed catalyst is prepared catalyst composition of aluminum compounds and modified with boron and/or silicon, which are impregnated aluminum compounds of the formula Al2O3n H2O in an aqueous solution of compounds of boron and/or silicon at a pH of 6.5 to 12 and a temperature of 70-100oC and compounds of alkali and/or alkaline earth metal, the modifying metal, chrome. Then this song tabletirujut or granularit any of the known methods (extrusion, molding, extrusion, sealing, etc.,) with a subsequent heat treatment.

The proposed method allows to significantly simplify the technology for producing catalyst for the dehydrogenation of paraffins compared to existing methods by eliminating multiple stages of cooking media: precipitation of aluminum hydroxide, spray drying or forming pellets, heat treatment of the medium in comparison with the known solutions.

Determination of the phase composition of the Mat is Odom, based on x-ray diffraction. Survey samples is carried out in SiC-radiation using a differential discrimination of the monochromator. The interval of angles on a scale from 2 10 to 75oC, the angular velocity detector 1/60oC.

Specific surface area determined by BET method, the volume of pore - water adsorption, particle size - sieve method.

The abrasion resistance is determined by the mass fraction of the loss in catalyst attrition. The method is based on the destruction of the catalyst particles in the fluidized layer and measuring the mass of particles carried by the air flow, the speed of which is stabilised.

The invention is illustrated by the following examples.

Example 1. The compound of aluminium of the formula Al2O3n H2O (n = 0,7) amorphous structure in the form of microspherical powder with a particle size of from 100 to 200 μm in a quantity of 25 kg load in propitiating with heating and stirring. There is poured a solution containing 5 kg of chromic anhydride, 460 g of potassium alkalis, 570 g of oxynitride zirconium and 150 g of tetraethoxysilane.

The impregnation is carried out at a temperature of 20oC for 1 hour. This was followed by drying in vacuum. The dried catalyst preggo physico-chemical and catalytic properties in table. N 2.

Examples 2 to 5. The catalyst is prepared analogously to example 1, different temperature impregnation, the structure of the aluminum compounds and the composition of the input modifying elements. Data on temperature, the structure of the aluminium compound and the modifying additives are given in table. N 1. And properties of the obtained catalysts is given in tab. N 2.

Example 6. In a reactor with a stirrer and heated pour 80 l of demineralized water, load 270 g of boric acid and heated to 70oC, then download 27 kg aluminum compounds of the formula Al2O3n H2O (n = 0.5) is in the form of microspherical powder amorphous structure. Bring the pH of the slurry to 6.5 mineral acid. The process is conducted at 85oC for 2 hours, then the precipitate is filtered off, dried in a chamber dryer at a temperature of 100oC to remove free moisture. After drying, the partially modified connection of the aluminum impregnated in the apparatus with heating and stirring, which serves a solution containing 250 g of potassium alkali and 180 g of cesium hydroxide, and 120 g of manganese hydroxide and 130 g of zirconium hydroxide and 5 kg of chromium trioxide. The impregnation is carried out at 60oC for 1 hour, followed by drying in a vacuum and calcining ASS="ptx2">

Examples 7 and 8. The catalyst is prepared analogously to example 6, different temperature impregnation and the pH of the suspension, the composition of the used catalyst components. All data are presented in table. NN 1 and 2.

Example 9. In a reactor with a stirrer and heated pour 18 l of water, then load 30 g silicates and 3 kg melkoporistaja aluminum compounds Al2O30,9 H2O having logoutresultevent structure and a particle size of predominantly 40 microns. Bring the pH of the suspension to 7.2 nitric acid. Process connection aluminium silicon conducted for 2 hours at 85oC. Then the precipitate is filtered off and dried at 110oC in a chamber dryer. After drying, the resulting powder was impregnated with 85oC with a solution containing 900 g of chromic anhydride and 25 g of lithium nitrate, 28 g of barium nitrate and 68 g of oxynitride zirconium. Moreover, the impregnation takes place simultaneously with obtaining a pasty mass of catalyst, which is then formed into pellets, dried at 110oC and annealed at 730oC. Obtain a catalyst with the properties shown in table. NN 1 and 2.

Example 10 (the prototype). 1200 g of aluminum oxide in the form of tablets impregnated with a solution containing 532,8 g trioxide, HRO is their 3 hours at a temperature of 140oC and for 16 hours at a temperature of 110oC in an atmosphere of air, then calicivirus for 2 hours at a temperature of 740oC in an atmosphere of air. Then carry out the impregnation of the catalyst with potassium acetate and the two-stage drying during the first 3 hours at a temperature of 140oC in vacuum, and then for 16 hours at a temperature of 110oC in an atmosphere of air. Then the product calicivirus for 2 hours at a temperature of 740oC in an atmosphere of air. Get the catalyst on the media of the following composition: 72.1 wt.% Al2O3; 25 wt.% Cr2O3; 0.9 wt.% ZrO2and 2 wt.% K2O and the properties are shown in table. N 2.

As seen from the examples, the catalyst of the proposed structure has high mechanical strength, allowing not to harm the environment, and the catalyst has a high activity and selectivity in the process of dehydrogenation of hydrocarbons.

1. Catalyst for dehydrogenation of C2-C5hydrocarbons containing oxides of aluminum, chromium, a compound modifier metal, alkaline and/or alkaline earth metal, wherein the catalyst additionally contains compounds of Kremneva from the group; zirconium, titanium, iron, gallium, cobalt, molybdenum, manganese, tin, and the catalyst formed during the heat treatment of aluminum compounds of the formula Al2O3n H2O, where n = 0.3 to 1.5, in conjunction with the compounds of the above elements, and has the following composition, wt.% (in terms of oxide):

Oxide of chromium calculated as Cr2O3- 12 - 23

The connection of reactive metal from the group of Zr, Ti, Fe, Ga, Co, Sn, Mo, Mn - 0,1 - 1,5

The compound of silicon and/or boron - 0,1 - 10,0

Connection alkaline and/or alkaline earth metal of 0.5 - 3.5

Alumina - Rest

2. The catalyst p. 1, characterized in that the compound of aluminium of the formula Al2O3n H2O, where n = 0,3 - 1,5, has amorphous or logoutresultevent structure or a partially crystalline structure.

3. The catalyst p. 1, characterized in that it has a value of specific surface area of 50 to 150 m2/g and a pore volume of 0.15 - 0.4 cm3/,

4. The catalyst p. 1, characterized in that it has a particle size of 40 to 200 microns.

5. A method of producing a catalyst for the dehydrogenation of C2-C5hydrocarbons, including impregnation of the carrier based on alumina with solutions of chromium compounds, alkaline and/IEM, that as the carrier is used as a compound of aluminium of the formula Al2O3n H2O, where n = 0.3 to 1.5, as a compound modifier metal used is at least one compound from the group of zirconium, titanium, iron, gallium, cobalt, molybdenum, manganese, tin, and impose additional compounds of silicon and/or boron in an amount of 0.1 - 10 wt.% impregnation of the carrier, followed by drying and coating with other catalyst components or in conjunction with other components of the catalyst and the catalyst after calcination has the following composition, wt.% (in terms of oxide):

Oxide of chromium calculated as Cr2O3- 12 - 23

The connection of reactive metal from the group of Zr, Ti, Fe, Ga, Co, Mo, Mn, Sn - 0,1 - 1,5

The compound of silicon and/or boron - 0,1 - 10,0

Connection alkaline and/or alkaline earth metal of 0.5 - 3.5

Alumina - Rest

6. The method according to p. 5, characterized in that the catalyst has a specific surface area of 50 to 150 m2/g, pore volume of 0.15 - 0.4 cm3/,

7. The method according to p. 5, characterized in that the compound of aluminium of the formula Al2O3n H2O, where n = 0,3 - 1,5, has amorphous or logoutresultevent structure or partly crystalline structure, the floor is placed aluminum formula Al2O3n H2O, where n = 0.3 to 1.5, is carried out in an aqueous solution of compounds of silicon and/or boron with a pH of 6.5 - 12 and at a temperature of 70 - 100oC, followed by drying and placement of the remaining components of the capacity.

9. The method according to p. 5, characterized in that the compound of aluminium of the formula Al2O3n H2O, where n = 0,3 - 1,5, impregnate both compounds boron and/or silicon, alkaline and/or alkaline earth metal, chromium, modifying metal capacity at a temperature of 20 - 100oC.

10. The method according to p. 5, characterized in that after impregnation the catalyst is dried in vacuum.

11. The method according to p. 5, characterized in that compounds of boron use boric acid.

12. The method according to p. 5, characterized in that compounds of silicon using a Hydrosol of silicon, tetraethoxysilane.

 

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