KR101095697B1 - Copper Oxide Supported Catalyst for Hydrocarbon Steam Cracking, Method for Preparing the Same, and Method for Preparing Olefin by Using the Same - Google Patents

Abstract

The present invention relates to a catalyst for pyrolysis of hydrocarbon steam in which copper oxide is supported on a surface of a composite catalyst, a method for preparing the same, and a method for preparing olefin using the same, the present invention comprising: a composite catalyst in which an oxide catalyst and a silicon carbide carrier are mixed and sintered; And it can provide a catalyst for pyrolysis of hydrocarbon steam comprising a copper oxide supported on the surface of the complex catalyst. According to the present invention, copper which is excellent in thermal / mechanical stability at high temperature and supports copper oxide in a composite catalyst that greatly improves the yield of light olefins, significantly reduces coke deposition while maintaining the yield of high light olefins. An oxide-supported hydrocarbon steam pyrolysis catalyst and a method for preparing the same can be provided, and a method for producing light olefin using the catalyst can be provided.

Hydrocarbon Steam Pyrolysis, Olefin, Catalyst, Copper Oxide, Impregnation, Dip Coating, Anti-Coking, Silicon Carbide

Description

Copper Oxide Supported Catalyst for Hydrocarbon Steam Cracking, Method for Preparing the Same, and Method for Preparing Olefin by Using the Same}

The present invention relates to a catalyst for hydrocarbon steam pyrolysis, a method for preparing the same, and a method for preparing olefin using the same, and more particularly, a catalyst for hydrocarbon steam pyrolysis on which copper oxide is supported on a surface of a composite catalyst, a method for preparing the same, and It is related with the manufacturing method of the used olefin.

Ethylene and propylene, which are important raw materials for petrochemical products, are mainly produced by pyrolyzing hydrocarbons containing paraffinic compounds such as natural gas, naphtha and gas oil at high temperatures of 800 ° C or higher in the presence of water vapor.

In order to increase the yield of ethylene and propylene in steam pyrolysis of hydrocarbons, the conversion of hydrocarbons or the selectivity of olefins should be increased. However, various methods have been proposed to increase the yield of olefins because there is a limit to increase the conversion of hydrocarbons or the selectivity of olefins by pure steam pyrolysis.

A steam pyrolysis method using a catalyst has been proposed as a method for improving the yield of ethylene and propylene in steam pyrolysis of hydrocarbons. US Patent No. 3,644,557 is a catalyst composed of magnesium oxide and zirconium oxide, US Patent No. 3,969,542 is a catalyst based on calcium aluminate, US Patent No. 4,111,793 is a manganese oxide catalyst supported on zirconium oxide, European Patent Publication No. 0212320 discloses an iron catalyst supported on magnesium oxide, US Pat. No. 5,600,051 discloses a method using a catalyst consisting of barium oxide, alumina, and silica. In addition, PCT Patent 2004/105939 discloses a process using a catalyst consisting of potassium magnesium phosphate, silica and alumina.

However, in the case of using such catalysts, it is known that the catalytic material acts as a heat medium in the hydrocarbon steam pyrolysis reaction to improve the yield of the olefin, and thus, the yield improvement of the olefin is insignificant compared with the case of using an inert carrier.

Russian Patent No. 1,011,236 discloses a potassium vanadate catalyst modified with boron oxide on an alumina carrier. However, when the alkali metal oxide or potassium vanadate catalyst is used, not only the yield improvement of the olefin by the catalyst is small but also inevitably occurs at high temperature for hydrocarbon decomposition. That is, the catalyst may exist in the liquid phase inside the high temperature pyrolysis reactor due to the low melting point of the catalyst components, and the catalyst activity is lost due to the volatilization of the catalyst components due to the rapid reaction gas flow and the reaction time progresses. There is this.

US Patent No. 7,026,263 discloses a method of using a hybrid catalyst composed of molybdenum oxide, alumina, silica, silicalite, zirconium oxide and the like. Such a catalyst has the advantage that the reaction can proceed at a low reaction temperature, but on the other hand it is difficult to apply directly to existing processes because it is operated at a very low hydrocarbon flow rate. In addition, the thermal stability of the catalyst is significantly lowered at the reaction temperature of 700 to 800 ℃ or more, there is a problem that the catalytic activity is lost.

The present invention relates to a catalyst for pyrolysis of hydrocarbon steam, a method for preparing the same, and a method for preparing light olefin using the same, and Korean Patent Application No. 10-2007-0050975 filed by the present inventors and Korean Patent Application Publication No. 10-2009-0050333 Supporting copper oxide on the surface of the hydrocarbon steam pyrolysis complex catalyst disclosed in, catalyst deactivation is significantly reduced by significantly reducing coke deposited on the catalyst surface while maintaining excellent thermal / mechanical stability, high olefin yield and selectivity at the high temperature of the existing catalyst. The present invention provides a catalyst for pyrolysis of hydrocarbon steam supported with copper oxide, a method for producing the same, and a method for preparing olefin using the same, which can greatly increase productivity by reducing an increase in reactor differential pressure due to coke deposition and increasing operation period.

In order to achieve the above object, the present invention provides a composite catalyst in which at least one oxide catalyst and a silicon carbide carrier are mixed and sintered selected from the group consisting of compounds represented by Formulas 1 to 3 and 4; And it provides a catalyst for pyrolysis of hydrocarbon steam comprising a copper oxide supported on the surface of the complex catalyst.

[Formula 1]

CrZr _j O _x

In Formula 1, j is 0.5 ≦ j ≦ 120, and x is a number satisfying the valence condition of j.

 [Formula 2]

CrZr _j A _k O _x

In Formula 2, A is Ti, Nb, Mo, V, Co, Ni, W, Fe, or a rare earth metal,

j is 0.5 ≦ j ≦ 120, k is 1 <k ≦ 50, x is a number satisfying the valence condition of j and k, and j / k is 0.5 ≦ j / k ≦ 5.

(3)

CrZr _i P _k O _x

In Formula 3, i is 0.1≤i≤50, k is 0.5≤k≤100, x is a number satisfying the valence condition of i, k, i / k is 0.01≤i / k≤3.

[Formula 4]

CrZr _i A _j P _k O _x

In Formula 4, A is Ti, Nb, Mo, V, Co, Ni, W, Fe or rare earth metal,

i is 0.1≤i≤50, j is 0.01≤j≤30, k is 0.5≤k≤100, x is a number satisfying the valence condition of i, k, i / k is 0.01≤i / k≤3 to be.

Here, it is more preferable that A in the formulas (2) and (4) of the oxide catalyst of the present invention is Ti.

In the catalyst for pyrolysis of hydrocarbon steam of the present invention, the copper oxide is more preferably copper oxide (CuO).

In addition, the hydrocarbon steam pyrolysis catalyst of the present invention is characterized in that the copper oxide content is 0.1 to 20 parts by weight based on 100 parts by weight of the composite catalyst.

In addition, the catalyst for pyrolysis of hydrocarbon steam of the present invention has a thickness of 0.01 to 100 μm of the copper oxide supported on the surface of the composite catalyst.

In addition, the hydrocarbon steam pyrolysis catalyst of the present invention is characterized in that the content of the oxide catalyst is 0.5 to 50 parts by weight based on 100 parts by weight of the silicon carbide carrier.

Hydrocarbon steam pyrolysis catalyst of the present invention is characterized in that it has a density of 0.5 to 3.5g / cm ³ .

The present invention comprises the steps of (a) preparing an aqueous solution by mixing water with Cr-containing compound, Zr-containing compound or Cr-Zr-containing compound; (B) adding an alkali or aqueous alkali solution to the aqueous solution and coprecipitation to prepare a slurry; (C) heating the slurry to reflux or hydrothermal treatment; (D) preparing one or more oxide catalysts selected from the group consisting of compounds represented by Chemical Formulas 1 to 3 and 4 by filtering, drying and calcining the slurry heated to reflux or hydrothermally; (E) preparing a composite catalyst by mixing and sintering the powder of the prepared oxide catalyst and the powder of silicon carbide carrier; (F) supporting copper oxide on the surface of the composite catalyst; And calcining the complex catalyst on which the copper oxide is supported (g).

Here, the method for producing a hydrocarbon steam pyrolysis catalyst of the present invention comprises the steps of (h) molding a complex catalyst; And (i) sintering the molded composite catalyst.

In addition, supporting copper oxide on the surface of the composite catalyst of the present invention may be carried out by a method selected from the group consisting of dip coating method, spraying method, evaporation drying method, simple deposition method, adsorption method, and solid phase reaction method. It may be carried out by coating or evaporative drying.

In the present invention, the dip coating method, the spray method, the evaporation drying method, the simple deposition method, or the adsorption method may include at least one copper salt selected from the group consisting of copper nitrate, copper sulfate, copper hydroxide, copper acetate, and copper chloride in water or an organic solvent. The dissolved solution can be used.

In addition, the dip coating method may use a copper salt solution having a copper salt molar concentration of 0.01 to 10 M in the copper salt solution.

In addition, the organic solvent may be ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, glycerin, hexylene glycol, butanediol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, and It may be at least one selected from the group consisting of 1,2-hexanediol.

In the present invention, the aqueous alkali solution may be an aqueous solution of at least one compound selected from the group consisting of ammonia, monoethanol amine, triethanol amine, potassium hydroxide, sodium hydroxide, ammonium hydroxide, potassium carbonate, and sodium carbonate.

In the present invention, step (a) further comprises a metal compound comprising at least one selected from the group consisting of Ti, Nb, Mo, V, Co, Ni, W, Fe and rare earth metals to prepare an aqueous solution, More preferably, an aqueous solution may be prepared by further adding a metal compound containing Ti.

In the present invention, the Cr-containing compound, Zr-containing compound or Cr-Zr-containing compound of step (a) is at least one selected from the group consisting of Ti, Nb, Mo, V, Co, Ni, W, Fe and rare earth metals. It may be a compound further comprising, more preferably a compound further comprising Ti.

In the method for preparing a catalyst for steam pyrolysis of the present invention, the firing of step (d) may be performed at a temperature of 750 to 1600 ° C. for 4 to 24 hours.

In addition, the firing of step (g) may be performed at a temperature of 800 to 1200 ° C. for 4 to 24 hours.

In addition, the sintering of step (e) or step (i) is characterized in that it is carried out for 2 to 24 hours at a temperature of 800 to 2000 ℃.

The present invention provides a method for producing an olefin which produces an olefin by steam pyrolyzing a hydrocarbon in the presence of a catalyst for hydrocarbon steam pyrolysis.

Here, in the method for preparing olefin of the present invention, hydrocarbon steam pyrolysis has a reaction temperature of 600 to 1000 ° C., a weight ratio of water vapor / hydrocarbon to 0.3 to 1.0, and a space velocity (LHSV) of 1 to 20 hr ⁻¹ . It is done.

In addition, the hydrocarbon steam pyrolysis product in the method for preparing an olefin of the present invention is characterized in that the ethylene / propylene ratio is 1.5 to 1.7.

In the process for preparing olefins of the present invention, steam pyrolysis may be performed by a reactor selected from the group consisting of a fixed bed reactor, a fluidized bed reactor, and a mobile bed reactor.

The present invention significantly reduces the coke deposited on the surface of catalyst while maintaining excellent thermal / mechanical stability, high olefin yield, and selectivity at the high temperature of the existing composite catalyst by supporting copper oxide on the surface of conventional hydrocarbon steam pyrolysis complex catalyst. By preventing the catalyst deactivation, it is possible to provide a catalyst for pyrolysis of hydrocarbon steam loaded with copper oxide that can significantly increase productivity by reducing the rise in reactor differential pressure due to coke deposition.

In addition, the present invention may provide a method for preparing a catalyst for pyrolysis of hydrocarbon steam on which the copper oxide is supported.

In addition, the present invention can provide a method for producing an olefin using the catalyst for pyrolysis of hydrocarbon steam on which the copper oxide is supported.

The present inventors have a catalyst for the thermal decomposition of hydrocarbon steam, the physical strength is high, the thermal stability at high temperature, and the catalyst for hydrocarbon steam pyrolysis that greatly improves the yield and selectivity of light olefins. It has been disclosed in 2007-0050975, Republic of Korea Patent Publication No. 10-2009-050333, Republic of Korea Patent Publication No. 10-2008-0029084, and Republic of Korea Patent Publication No. 10-2008-0029085.

The present inventors have found that a catalyst in which copper oxide is supported on the surface of the catalyst for pyrolysis of hydrocarbon steam of the above-mentioned document shows excellent thermal / mechanical stability, high olefin yield, and selectivity at a high temperature in view of the catalyst for pyrolysis of the conventional hydrocarbon steam of the above-mentioned document. Maintaining, while significantly reducing the coke deposited on the surface of the catalyst to prevent catalyst deactivation, and to increase the operating period by reducing the rise in the reactor differential pressure due to the coke deposition, it is confirmed that greatly improves the productivity, based on the copper oxide of the present invention A catalyst for pyrolysis of hydrocarbon water vapor was completed.

Hereinafter, the present invention will be described in detail including examples.

The present invention is a composite catalyst in which at least one oxide catalyst selected from the group consisting of compounds represented by the following formulas (1) to (3) and (4) and silicon carbide carrier are mixed and sintered; And it provides a catalyst for pyrolysis of hydrocarbon steam comprising a copper oxide supported on the surface of the complex catalyst.

Hydrocarbon steam pyrolysis catalyst of the present invention is characterized in that the oxide catalyst containing Cr and Zr defined by the formula (1).

[Formula 1]

CrZr _j O _x

In Formula 1, j is 0.5 ≦ j ≦ 120, preferably 5 ≦ j ≦ 90, more preferably 70 ≦ j ≦ 90, and x is a number satisfying the valence condition of j.

In addition, the oxide catalyst for pyrolysis of hydrocarbon steam of the present invention includes Cr and Zr and at least one metal component selected from the group consisting of Ti, Nb, Mo, V, Co, Ni, W, Fe and rare earth metals (A). It is characterized in that the oxide catalyst comprising a formula (2).

[Formula 2]

CrZr _j A _k Ox

In Formula 2, j is 0.5≤j≤120, preferably 5≤j≤90, more preferably 70≤j≤, and k is 1 <k≤50, preferably 5≤k≤30, Preferably, 15 ≦ j ≦ 28, x is a number satisfying the valence condition of j and k, j / k is 0.5 ≦ j / k ≦ 5, and preferably 2 ≦ j / k ≦ 3.5.

In addition, the oxide catalyst for pyrolysis of hydrocarbon steam of the present invention is characterized in that it is defined by the formula (3) as a phosphate catalyst containing Cr and Zr.

(3)

CrZr _i P _k O _x

In Formula 3, i is 0.1≤i≤50, preferably 0.5≤i≤15, k is 0.5≤k≤100, preferably 1≤k≤4, and x is the valence condition of i, k It is a satisfying number, i / k is 0.01≤i / k≤3, preferably 0.1≤i / k≤1.5.

In addition, the oxide catalyst for pyrolysis of hydrocarbon steam of the present invention comprises Cr and Zr and at least one metal component selected from the group consisting of Ti, Nb, Mo, V, Co, Ni, W, Fe and rare earth metals (A) It is characterized in that the phosphate catalyst comprising a formula (4).

[Formula 4]

CrZr _i A _j P _k O _x

In Formula 4, 0.1≤i≤50, preferably 0.5≤i≤15, j is 0.01≤j≤30, preferably 0.01≤j≤10, k is 0.5≤k≤100, and x is It is a number which satisfy | fills the valence condition of i and k, i / k is 0.01 <= i / k <= 3, Preferably it is 0.1 <= i / k <= 1.5.

In Formulas 2 and 4, A is more preferably Ti.

In addition, the copper oxide of the hydrocarbon steam pyrolysis catalyst of the present invention is preferably copper oxide (CuO).

The hydrocarbon steam pyrolysis catalyst of the present invention preferably has a copper oxide content of 0.1 to 20 parts by weight based on 100 parts by weight of the composite catalyst. When the copper oxide content is less than 0.1 part by weight based on 100 parts by weight of the composite catalyst, the effect of reducing the amount of carbon deposited on the surface of the composite catalyst during the hydrocarbon pyrolysis reaction is insignificant. When the copper oxide content exceeds 20 parts by weight, the hydrocarbon pyrolysis of the composite catalyst is present. It reduces the high activity of the reaction and degrades the thermal / mechanical stability.

In addition, the hydrocarbon steam pyrolysis catalyst of the present invention preferably has a thickness of 0.01 to 100 μm of the copper oxide supported on the surface of the composite catalyst. When the thickness of the copper oxide supported on the surface of the composite catalyst is less than 0.01 μm, the amount of CuO supported is too small, so that the effect of reducing the amount of carbon deposited on the surface of the composite catalyst during hydrocarbon pyrolysis reaction is insignificant, exceeding 100 μm. In this case, the high activity of the hydrocarbon pyrolysis reaction of the multicatalyst can be reduced and the thermal / mechanical stability can be degraded.

In addition, the hydrocarbon steam pyrolysis catalyst of the present invention is preferably 0.5 to 50 parts by weight based on 100 parts by weight of the silicon carbide carrier for hydrocarbon steam pyrolysis. If the content of the oxide catalyst is less than 0.5 parts by weight, it is difficult to exhibit the performance as a catalyst, and if it exceeds 50 parts by weight, the strength of the catalyst is weakened.

In addition, the hydrocarbon steam pyrolysis catalyst of the present invention preferably has a density of 0.5 to 3.5 g / cm ³ , a surface area of 50 m ² / g or less, and a compressive strength of 1000 N or more. When the surface area is larger than 50 m ² / g, the amount of coke deposition increases, and when the compressive strength is less than 1000N, the strength is weak and easily broken.

The method for preparing a hydrocarbon steam pyrolysis catalyst of the present invention comprises the steps of: (a) preparing an aqueous solution by mixing water with a Cr-containing compound, a Zr-containing compound, or a Cr-Zr-containing compound; (B) adding an alkali or aqueous alkali solution to the aqueous solution and coprecipitation to prepare a slurry; (C) heating the slurry to reflux or hydrothermal treatment; (D) preparing at least one oxide catalyst selected from the group consisting of compounds represented by the formulas (1) to (3) and (4) by filtering, drying, and calcining the reflux heated or hydrothermally treated slurry; (E) preparing a composite catalyst by mixing and sintering the powder of the prepared oxide catalyst and the powder of silicon carbide carrier; (F) supporting copper oxide on the surface of the composite catalyst; And calcining the complex catalyst on which the copper oxide is supported (g).

Hereinafter, each step of the preparation method of the catalyst for pyrolysis of hydrocarbon steam of the present invention will be described in detail.

Step (a) is a step of preparing an aqueous solution by mixing water with a Cr-containing compound, a Zr-containing compound or a Cr-Zr-containing compound.

The Cr-containing compound and the Zr-containing compound or Cr-Zr-containing compound may be used in the form of salts such as sulfates, nitrates, oxalates, halides or chlorides, and nitrates. It is preferable to use nitrates.

 The metal compound, that is, the Cr containing compound and the Zr containing compound or the Cr-Zr containing compound may be further mixed with a third metal compound, and the third metal compound is a metal component as Ti, Nb, Mo, V, Co At least one selected from the group consisting of Ni, W, Fe and rare earth metals may be used, and Ti, Ni, rare earth metals are preferably used, and Ti is more preferably used.

In addition, the Cr-containing compound or Zr-containing compound or Cr-Zr-containing compound is at least one member selected from the group consisting of Ti, Nb, Mo, V, Co, Ni, W, Fe and rare earth metals as the third metal component. It may be further included, Ti, Ni, rare earth metal is preferably included, and more preferably Ti is included.

The metal component of each of the third metal compounds may be used in the form of a salt, an acid, an oxide, a hydroxide, or an alkoxide. When the metal component of the third metal compound is in the form of an alkoxide precursor, since the alkoxide can be hydrolyzed in water and precipitated as a solid salt, it can be dissolved by adding a strong acid such as nitric acid.

The metal component of the third metal compound may be used after being dissolved in water and mixed with Cr and Zr aqueous solution or by being dissolved in water together with Cr and Zr precursors.

The aqueous solution in which the above components are dissolved may be stirred for 1 hour or more so as to be sufficiently mixed in a temperature range of 40 to 80 ° C, preferably 60 to 70 ° C, while heating and stirring.

Step (b) is a step of preparing a slurry by adding an alkali or aqueous alkali solution to the aqueous solution of step (a) to adjust the pH to 7 to 9, preferably 8 to 8.5, and coprecipitation.

As the alkali of step (b), ammonia, monoethanol amine, triethanol amine, potassium hydroxide, sodium hydroxide, ammonium hydroxide, potassium carbonate, or sodium carbonate may be used alone or in combination of two or more thereof, and aqueous solutions of these alkalis may be used. . Preferably, ammonia or an aqueous ammonia solution is used.

Step (c) is a step of subjecting the slurry of step (b) to reflux heating at the same temperature as step (a) for at least 12 hours or in an autoclave in a temperature range of 60 to 150 ° C.

Step (d) is a step of preparing an oxide catalyst by filtration, drying and calcining the heated or hydrothermally treated slurry of step (c).

It is preferable to dry the said drying at 120 degreeC for 2 hours or more.

The firing of step (d) is preferably carried out at 750 to 1600 ° C for 4 to 24 hours. When firing in the temperature range there is an effect that the firing is not made rapidly, the activity of the catalyst is not lost. In addition, when the firing time is less than 4 hours, the firing is not completely performed, and when the firing time is longer than 24 hours, the firing is not further progressed and is not necessary.

Step (e) is a step of mixing and sintering the powder of the prepared oxide catalyst defined in Formulas 1 to 4 and the powder of silicon carbide carrier prepared by the completion of step (d). It is preferable for the hydrocarbon steam pyrolysis reaction that the oxide catalyst is mixed in an amount of 0.5 to 50 parts by weight based on 100 parts by weight of the silicon carbide carrier. When the oxide catalyst component is mixed at less than 0.5 parts by weight, it is difficult to exhibit the performance as a catalyst. When the oxide catalyst component is mixed at more than 50 parts by weight, the strength of the catalyst is weakened. In addition to the step of mixing the oxide catalyst component and the carrier may be mixed with the binder.

In order to use a silicon carbide carrier, silicon carbide precursors of silicon and carbon may be mixed with the oxide catalyst component. At this time, when the sintering process is performed, silicon and carbon are converted into silicon carbide.

Sintering of step (e) is preferably carried out for 2 to 24 hours at a temperature of 800 to 2000 ℃. When the sintering is performed at less than 800 ℃ is not preferable because the sintering is not performed, and if the sintering is carried out above 2000 ℃ may be lost of the catalyst component and silicon carbide. In addition, when the sintering time is less than 2 hours, the sintering time is too short, so that the sintering is not completely performed, and when the sintering time is longer than 24 hours, the sintering no longer proceeds.

In particular, when the hydrocarbon steam pyrolysis reaction is performed at a temperature of 800 ° C., it is preferable that the product ethylene / propylene ratio is 1.5 to 1.7. As the pyrolysis reaction temperature is higher than 800 ° C., propylene selectivity is lowered.

Step (f) is a step of supporting copper oxide on the surface of the composite catalyst.

In order to support copper oxide on the surface of the composite catalyst of the present invention, a dip coating method, a spraying method, an evaporation drying method, a simple deposition method, a adsorption method, or a solid phase reaction method, which is generally known, may be used. Coating or evaporative drying can be used.

The impregnation method is a method of contacting and supporting an active material solution on a previously formed support, and there are a spray method, an evaporation drying method, a dip coating method, an incipient wetness method, and an adsorption method depending on the contact method of the solution and the support.

Spraying is a method of spraying an active material solution on a support while stirring or shaking the support. Spray drying (spray drying) is a method of spraying a solution of the active substance from all directions while free-falling the support, and then drying and supporting it immediately.

The evaporation drying method is a method in which an active material is supported by evaporating a solvent by putting a support in an active material solution and gradually heating it.

Dip coating is a method in which the support is immersed in a solution of a certain concentration in which the active substance is dissolved, and then taken out and dried to support the active substance.

In the simple deposition method, if the active material solution is added to the dried support in an amount that can be absorbed into the pores, the solution is absorbed into the support. Therefore, the active material is uniformly distributed in the pores. This is supported.

Adsorption is a method in which a support is added to a solution in which an active material is dissolved to adsorb the active material to the surface of the support, followed by filtration and washing only the active material that is adsorbed.

Solid state reaction is a method in which a solid oxide such as copper oxide and copper carbonate is mixed with a solid composite catalyst and heat treated at a high temperature to support copper oxide on the surface of the composite catalyst.

In the present invention, a solution in which copper salt compounds such as copper nitrate, copper sulfate, copper hydroxide, copper acetate, or copper chloride are dissolved in water or an organic solvent when using dip coating, spraying, evaporation drying, simple deposition or adsorption Can be used.

When the dip coating method is used, it is preferable to use a copper salt solution having a molar concentration of copper salt of 0.01 to 10 M. When the molar concentration of the copper salt compound is less than 0.01M, the amount of copper oxide supported is small, so that the effect of reducing the amount of carbon deposited on the surface of the complex catalyst during hydrocarbon pyrolysis reaction is insignificant. Reduces the high activity of and lowers the thermal / mechanical stability.

In the present invention, as the organic solvent, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, glycerin, hexylene glycol, butanediol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol Or 1,2-hexanediol may be used alone or in combination of two or more thereof.

Step (g) is a step of preparing a complex catalyst for pyrolysis of hydrocarbon steam by calcining the complex catalyst on which the copper oxide is supported.

The firing of step (g) is preferably carried out at a temperature of 800 to 1200 ℃ 4 to 24 hours. When firing is performed at less than 800 ° C., the copper precursor is calcined to produce copper oxide, which does not stably bond to the surface of the composite catalyst. When firing is performed at more than 1200 ° C., the copper oxide may be dissolved and separated from the composite catalyst. In addition, when the sintering time is less than 4 hours, the firing time is too short, so that the firing is not completely performed, and when the sintering time exceeds 24 hours, the firing does not proceed any more.

Method for producing a hydrocarbon steam pyrolysis catalyst of the present invention comprises the steps of (h) forming a complex catalyst; And (i) sintering the molded composite catalyst.

Step (h) is a step of forming the complex catalyst of step (e) to make a specific shape such as LASIK ring. The composite catalyst is made into a specific shape by compression molding or extrusion molding.

Step (i) is the step of sintering the molding of the specific shape of step (h). The molded product of step (h) is reduced in volume during the sintering process to produce a composite catalyst having a desired size, density and surface area.

The sintering of step (i) is preferably carried out for 2 to 24 hours at a temperature of 800 to 2000 ℃. The reason why the sintering temperature and the sintering time are preferable is the same as described in step (e).

After completing steps (h) and (i), step (f) of supporting the copper oxide on the surface of the composite catalyst and step (g) of firing the composite catalyst on which the copper oxide is supported may be performed. f) and step (g) may be performed in the same manner as described above.

As described above, the catalyst for hydrocarbon steam pyrolysis, which is completed until the molding of the composite catalyst, the sintering, the support of copper oxide and the sintering of the supported composite catalyst, is the same as described in the description of the catalyst for thermal decomposition of hydrocarbon steam of the present invention.

The present invention provides a method for producing an olefin for producing light olefins by steam pyrolysis of hydrocarbons in the presence of a catalyst for pyrolysis of hydrocarbon steam prepared by the above method.

The light olefin according to the present invention means an olefin having 4 or less carbon atoms, and particularly ethylene, propylene, and the like.

Hydrocarbon steam pyrolysis reaction for preparing the light olefin may be carried out under the condition that the reaction temperature is 600 to 1000 ℃, the weight ratio of water vapor / hydrocarbon 0.3 to 1.0, the space velocity (LHSV) 1 to 20 hr ^-1 . .

Here, the pyrolysis reaction is not preferable when the reaction temperature of the hydrocarbon steam pyrolysis reaction for preparing the light olefin is less than 600 ° C., and when it exceeds 1000 ° C., by-products such as methane, carbon dioxide, and coke are produced in large quantities. It is not preferable because it becomes. In addition, when the weight ratio of water vapor / hydrocarbon is less than 0.3, it is not preferable to increase coke formation as a by-product, and if it exceeds 1.0, it is not preferable because the amount of reactants is small and the yield is reduced. In addition, when the space velocity (LHSV) is less than 1 hr ^{- 1} , the residence time is increased and the side products, such as methane, are not preferable, and when it exceeds 20 hr ^-1 , the residence time is short and the conversion rate of hydrocarbon pyrolysis reaction is preferable. Not.

In the above reaction, applicable reactors include a fixed bed reactor, a fluidized bed reactor or a mobile bed reactor. In particular, when using a fixed bed reactor, it is possible to use a catalyst molded in the form of a sphere or pellet, but there is a problem that a large pressure difference is formed in the catalyst layer. Therefore, in order to solve this problem, it is preferable to use a catalyst molded in a LASIK form or other special form so as to increase the porosity of the catalyst layer as much as possible.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and various changes and modifications within the scope and spirit of the present invention are apparent to those skilled in the art. Naturally, such modifications and variations fall within the scope of the appended claims.

Example  One

2.86 g of Ti [OCH (CH ₃ ) ₂ ] was added to distilled water at 60 ° C., and nitric acid was gradually dropped and stirred until it became clear. 12.35 g of ZrO (NO ₃ ) ₂ .H ₂ O and 0.24 g of Cr (NO ₃ ) ₃ .9H ₂ O were added thereto, followed by stirring for 2 hours to prepare an aqueous solution. The solution was co-precipitated by adjusting the pH to 8 while slowly dropping ammonia water into the aqueous solution, and heated to reflux for 12 hours. The co-precipitated aqueous solution was washed with distilled water while filtering and the catalyst was separated, and then placed in a 120 ° C. dryer for 6 hours to remove moisture. The dried catalyst was placed in an electric furnace and calcined by heating at 800 ° C. for 6 hours in an air atmosphere. The catalyst prepared as described above showed a composition of CrZr _{83 .3} Ti _{16 .7} O _x . The catalyst powder thus prepared was mixed with 500 µm size silicon carbide powder having a purity of 99.5% and vacuum sintered at 1900 ° C. for 12 hours. The catalyst completed by sintering according to the above procedure has a composition in which the CrZr _{83 .3} Ti _{16 .7} O _x is 5% by weight based on the weight of silicon carbide. The SiC composite catalyst containing the catalyst component thus prepared was pulverized to a size of 355-600 μm and calcined by heating at 1000 ° C. for 6 hours in an air atmosphere. The catalyst was also designated as Cat 1.

Example  2

Cu (NO ₃₎ 0.094g of 50 ml of distilled water at room temperature was added thereto and stirred for ₂ .3H ₂ O. The 355-600 μm composite catalyst prepared in 1 g of Example 1 was added thereto, distilled under reduced pressure using a rotary vacuum distillation apparatus at 70 ° C., and stored in a 120 ° C. dryer for 6 hours to remove moisture. The dried catalyst was placed in an electric furnace and calcined by heating at 1000 ° C. for 6 hours in an air atmosphere.

Example  3

Except in Example 2 that the addition of 0.16 g of _{Cu (NO 3) 2 .3H 2} O was carried out as Example 2.

Comparative example  One

Alumina having a surface area of 0.18 m ² / g was pulverized to 355-600 μm and calcined at 1000 ° C.

Comparative example  2

Silica having a surface area of 120 m ² / g was pulverized to 355-600 μm and calcined at 1000 ° C. was used.

Comparative example  3

Cu (NO ₃₎ in 0.32g of distilled water 50 ml at room temperature was added thereto and stirred for ₂ .3H ₂ O. 2 g of 355-600 μm of Alumina of Comparative Example 1 was added thereto, and distilled under reduced pressure at 70 ° C. using a rotary vacuum distillation apparatus, and stored in a 120 ° C. dryer for 6 hours to remove moisture. The dried sample was placed in an electric furnace and calcined by heating at 1000 ° C. for 6 hours in an air atmosphere.

Comparative example  4

Comparative Example 3 was carried out in the same manner as in Comparative Example 3, except that silica prepared in Comparative Example 2 was added instead of Alumina.

[Test Example 1]

The catalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were used for the hydrocarbon steam pyrolysis reaction in the following manner.

Hexane was used as the hydrocarbon. After filling a 5 cm high catalyst into a quartz tube having an outer diameter of 1/4 ", the reaction temperature was maintained at 800 deg. The injection ratio of hexane and water was 5: 2 by weight ratio, and the flow rate of hexane was adjusted so that LHSV was 5hr ⁻¹ . Hexane and water were injected using a syringe pump, but each was vaporized at a temperature of 300 and 400 ° C. in a vaporizer, and then contacted with the catalyst layer in a well mixed state. After the reaction, the catalyst was collected to measure the weight of the coke deposited on the catalyst, and the amount of coke deposited on the sample was calculated by the following equation.

[Equation 1]

Coke production (% by weight) = weight of generated coke / weight of filled sample × 100

Example  4

A low speed saw device was obtained by compression molding and sintering a SiC composite catalyst containing 10 wt% CrZr _{83 .3} Ti _{16 .7} O _x in a LASIK ring form in the first embodiment. It was carried out in the same manner as in Example 1 except that it was prepared in a rectangular specimen of 3 * 4 * 32 mm using. This catalyst was named Cat 2.

Example  5

In distilled water at room temperature by the addition of _{Cu (NO 3) 2 .3H 2} O was prepared in the copper nitrate aqueous solution of a 0.5M concentration. Here, the 3 * 4 * 32 mm rectangular complex catalyst prepared in Example 4 was soaked for 1 hour, taken out, stored at room temperature for 1 h, and stored in a 120 ° C. dryer for 6 hours to remove moisture. The dried catalyst was placed in an electric furnace and calcined by heating at 1000 ° C. for 6 hours in an air atmosphere.

Example  6

Except for using the copper nitrate aqueous solution of 2.0M concentration in Example 5 was carried out in the same manner as in Example 5.

Example  7

Except for using a 4.0M copper nitrate aqueous solution in Example 5 was carried out in the same manner as in Example 5.

Example  8

The catalyst prepared in Example 7 was used in a hexane catalytic steam pyrolysis reaction for 2 hours under the same conditions as in Test Example 2, and then recovered and regenerated by burning the coke for 2 hours at 750 ° C. in an air atmosphere.

[Test Example 2]

Using three 3 * 4 * 32 mm rectangular catalysts each prepared in the same manner as in Example 4-8, the hydrocarbon steam pyrolysis was carried out in the following manner. At this time, the filling rate of the complex catalyst was about 27%. Hexane was used as the hydrocarbon.

The reactants hexane and water were injected into the reactor by a syringe pump. At this time, the injection ratio of hexane and water was 2: 1 by weight ratio, and the naphtha flow rate was adjusted to be 2.5 hr ⁻¹ . Hexane and water injected into the reactor were each mixed through a vaporizer and then passed through a primary preheater heated to 330 ° C. and then a reactor charged with a catalyst through a secondary preheater heated to 330 ° C. (length: 300 cm, Diameter: 0.52 cm).

The reactor is heated by an electric furnace and a catalytic pyrolysis reaction takes place as the steam-hexane mixture passed through the secondary preheater passes through the reactor. At this time, the temperature of the reactor was maintained at 820 ℃. The decomposition product discharged through the reactor was quantitatively analyzed by gas chromatography, and the yield of the decomposition product was calculated by Equation 2 below. In addition, the sample after the reaction was collected to measure the weight of the coke deposited on the sample, and the amount of coke deposited on the sample was calculated by Equation 1 of Test Example 1.

[Equation 2]

Yield of product (% by weight) = weight of product / weight of injected hexane × 100

division Catalyst name CuO loading (% by weight) Coke production amount (% by weight) Example One Cat 1 0 12.8 2 3wt% CuO / Cat 1 2.1 1.0 3 5wt% CuO / Cat 1 3.6 0.5 Comparative example One Al ₂ O ₃ 0 13.7 2 SiO ₂ 0 9.8 3 5wt% CuO / Al ₂ O ₃ 3.8 13.6 4 5wt% CuO / SiO ₂ 4.5 12.2

Note: CuO loading (% by weight) = CuO weight / (composite catalyst weight + CuO weight) x 100

Through the above Table 1, the composite catalyst of Example 1, which is a composite catalyst in which an oxide catalyst component having CrZr _83.3 Ti _16.7 O _x composition and silicon carbide as a carrier are mixed in the existing invention [Korean Patent Publication No. 10-2009-0050333] The thermal / mechanical stability at high temperatures is excellent and not only improves the selectivity and yield of light olefins, but also has little deactivation by coke. However, hydrocarbon steam pyrolysis is very high in the amount of reactants at a high temperature of more than 820 ℃ because the amount of coke deposited is very high. Therefore, although the amount of coke deposition was also very low, the composite catalyst of Example 1, which was invented, required a catalyst in which the amount of coke deposition was significantly reduced.

In the present invention, the amount of coke deposited in the composite catalyst prepared in Example 1 was 12.8 wt%. However, in the copper oxide-supported composite catalysts of Examples 2 and 3, in which the copper oxide was loaded at 2.1 wt% and 3.6 wt% on the surface of the composite catalyst, the amount of coke was significantly reduced to 1.0 wt% and 0.5 wt%, respectively.

However, as in Comparative Example 1 and Comparative Example 2, the amount of coke deposition of Comparative Examples 3 and 4, in which copper oxide was supported on the surface of alumina and silica, was not reduced, but rather, the copper oxide was supported on the surface of silica. For Comparative Example 4, the amount of coke deposition increased from 9.8% by weight to 12.2% by weight.

This was found to selectively reduce the formation of coke deposited by hydrocarbon pyrolysis reaction only when copper oxide is supported on the surface of the composite catalyst prepared as in Example 1.

division Catalyst name reaction
time
(h) Product yield (% by weight) Coke Production Ethylene Propylene Ethylene
+
Propylene H ₂ CO
+
CO ₂ (weight %) Example 4 Cat 2 2 46.3 15.5 61.8 0.9 1.2 15.1 8 29.5 Example 5 0.5M CuO
/ Cat 2 2 47.8 15.1 62.9 0.9 1.0 9.9 Example 6 2.0M CuO
/ Cat 2 2 47.0 15.2 62.2 0.8 1.1 7.4 8 13.0 Example 7 4.0M CuO
/ Cat 2 2 47.1 15.7 62.8 0.8 1.2 2.1 8 5.5 Example 8 4.0M CuO
/ Cat 2 2 47.1 15.8 62.9 0.8 1.2 1.8

Through Table 2, prepared in the same form as the existing patent [Korea Patent Publication No. 10-2009-0050333] to use the copper oxide-coated composite catalyst developed by the present invention in the pilot or factory-level Cracker tube A copper oxide was coated on the surface of the composite catalyst using an aqueous copper nitrate solution.

The catalyst prepared in the rectangular planar form of the LASIK ring composite catalyst of Example 4 using a low speed saw equipment had ethylene and propylene yields of 46.3 and 15.5 wt%, respectively, with a total of 61.8 wt% and hydrogen and carbon monoxide. The yields of sum of and carbon dioxide were 0.9 and 1.2 wt%, respectively. The amount of coke deposited after 2 hours of reaction was 15.1 wt% and the amount of coke deposited after 8 hours of reaction increased to 29.5 wt%.

However, the catalysts of Examples 5, 6, and 7 in which copper oxide was supported by dip coating the composite catalyst of Example 4 in 0.5 M, 2.0 M, and 4.0 M concentrations of copper nitrate aqueous solution were obtained in ethylene and propylene yields after 2 hours of reaction. The total olefin yield was 62.9, 62.2, and 62.8 wt%, respectively, and the yield of the olefin was similar or increased slightly compared with that of the composite catalyst of Example 4, in which copper oxide was not supported. This shows that even though copper oxide is supported on the surface of the composite catalyst, the activity of the catalyst is maintained.

In addition, the sum of ethylene and propylene yields after 8 hours of reaction remained almost the same. The amount of coke deposited on the catalyst was 9.9, 7.4 and 2.1 wt%, respectively, which was significantly reduced compared to 15.1 wt% of Example 4, and as the concentration of copper nitrate solution increased, the supported amount of copper oxide increased and deposited on the catalyst surface. The amount of coke to be reduced. The amount of coke deposited on the catalyst surface after 8 hours of reaction was also very low as compared to 29.5% by weight of Example 4 at 13.0 and 5.5% by weight, as shown in Examples 6 and 7. In addition, the yield of hydrogen, carbon monoxide, and carbon dioxide, which are the products of complete oxidation, did not increase in the composite catalyst loaded with copper oxide, compared with the composite catalyst of Example 4.

The catalyst of Example 7 was recovered by using the catalyst of Example 7 in the hexane-contact steam pyrolysis reaction under the same conditions as in Test Example 2, and recovered by burning the coke for 2 hours at 750 ° C. in an air atmosphere. And olefin yield and selectivity were the same, and the content of coke deposited on the catalyst surface was maintained similarly. This means that the copper oxide coated on the catalyst surface is stably supported and can be reused once the copper oxide-coated composite catalyst is used for hydrocarbon catalytic steam pyrolysis and then removed from the Cokeman oxygen atmosphere deposited on the surface. Will look.

Claims (25)

A composite catalyst in which at least one oxide catalyst and a silicon carbide carrier are mixed and sintered selected from the group consisting of compounds represented by Formulas 1 to 3 and 4; And Copper oxide supported on the surface of the composite catalyst Catalyst for pyrolysis of hydrocarbon steam, comprising. [Formula 1] CrZr _j O _x In Formula 1, j is 0.5 ≦ j ≦ 120, and x is a number satisfying the valence condition of j.  [Formula 2] CrZr _j A _k O _x In Formula 2, A is Ti, Nb, Mo, V, Co, Ni, W, Fe, or a rare earth metal, j is 0.5 ≦ j ≦ 120, k is 1 <k ≦ 50, x is a number satisfying the valence condition of j and k, and j / k is 0.5 ≦ j / k ≦ 5. (3) CrZr _i P _k O _x In Formula 3, i is 0.1≤i≤50, k is 0.5≤k≤100, x is a number satisfying the valence condition of i, k, i / k is 0.01≤ i / k≤3. [Formula 4] CrZr _i A _j P _k O _x In Formula 4, A is Ti, Nb, Mo, V, Co, Ni, W, Fe or rare earth metal, i is 0.1≤i≤50, j is 0.01≤j≤30, k is 0.5≤k≤100, x is a number satisfying the valence condition of i, k, i / k is 0.01≤i / k≤3 to be. The catalyst for pyrolysis of hydrocarbon steam according to claim 1, wherein A in Formulas 2 and 4 is Ti. The catalyst for pyrolysis of hydrocarbon steam according to claim 1 or 2, wherein the copper oxide is copper oxide (CuO). The catalyst for hydrocarbon steam pyrolysis according to claim 1 or 2, wherein the catalyst for pyrolysis of hydrocarbon steam has a copper oxide content of 0.1 to 20 parts by weight based on 100 parts by weight of the composite catalyst. The catalyst for pyrolysis of hydrocarbon steam according to claim 1 or 2, wherein the catalyst for pyrolysis of hydrocarbon steam is 0.5 to 50 parts by weight based on 100 parts by weight of the silicon carbide carrier. Cr-containing compounds and Zr-containing compounds; Or (a) preparing an aqueous solution by mixing water with a Cr-Zr-containing compound; (B) adding an alkali or aqueous alkali solution to the aqueous solution and coprecipitation to prepare a slurry; (C) heating the slurry to reflux or hydrothermal treatment; (D) preparing at least one oxide catalyst selected from the group consisting of compounds represented by the following formulas (1) to (3) and (4) by filtering, drying, and calcining the reflux heated or hydrothermally treated slurry; (E) preparing a composite catalyst by mixing and sintering the powder of the prepared oxide catalyst and the powder of silicon carbide carrier; (F) supporting copper oxide on the surface of the composite catalyst; And Calcining the complex catalyst on which the copper oxide is supported (g) Method for producing a catalyst for pyrolysis of hydrocarbon steam comprising. [Formula 1] CrZr _j O _x In Formula 1, j is 0.5 ≦ j ≦ 120, and x is a number satisfying the valence condition of j.  [Formula 2] CrZr _j A _k O _x In Formula 2, A is Ti, Nb, Mo, V, Co, Ni, W, Fe, or a rare earth metal, j is 0.5 ≦ j ≦ 120, k is 1 <k ≦ 50, x is a number satisfying the valence condition of j and k, and j / k is 0.5 ≦ j / k ≦ 5. (3) CrZr _i P _k O _x In Formula 3, i is 0.1≤i≤50, k is 0.5≤k≤100, x is a number satisfying the valence condition of i, k, i / k is 0.01≤i / k≤3. [Formula 4] CrZr _i A _j P _k O _x In Formula 4, A is Ti, Nb, Mo, V, Co, Ni, W, Fe or rare earth metal, i is 0.1≤i≤50, j is 0.01≤j≤30, k is 0.5≤k≤100, x is a number satisfying the valence condition of i, k, i / k is 0.01≤i / k≤3 to be. 7. The method of claim 6, further comprising the steps of (h) shaping the complex catalyst in step (e); And (i) sintering the molded composite catalyst. 8. The method of claim 6 or 7, wherein the support of copper oxide on the surface of the composite catalyst is performed by a method selected from the group consisting of dip coating, spraying, evaporation drying, simple deposition, adsorption, and solid phase reaction. Method for producing a catalyst for pyrolysis of hydrocarbon steam, characterized in that. The method for preparing a hydrocarbon pyrolysis catalyst according to claim 8, wherein the copper oxide is supported on the surface of the composite catalyst by a dip coating method or an evaporation drying method. The method of claim 8, wherein the dip coating method, the spraying method, the evaporation drying method, the simple deposition method, or the adsorption method comprises at least one copper salt selected from the group consisting of copper nitrate, copper sulfate, copper hydroxide, copper acetate, and copper chloride. A method for producing a hydrocarbon steam pyrolysis catalyst, characterized by using a copper salt solution dissolved in a solvent. The method of claim 10, wherein the dip coating method uses a copper salt solution having a copper salt molar concentration of 0.01 to 10 M in a copper salt solution. The organic solvent of claim 10, wherein the organic solvent is ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, glycerin, hexylene glycol, butanediol, polyethylene glycol, polypropylene glycol, 1,2- Pentanediol, and 1,2-hexanediol, a method for producing a hydrocarbon steam pyrolysis catalyst, characterized in that at least one member selected from the group consisting of. The method of claim 6 or 7, wherein the alkali of step (a) is at least one compound selected from the group consisting of ammonia, monoethanol amine, triethanol amine, potassium hydroxide, sodium hydroxide, ammonium hydroxide, potassium carbonate, and sodium carbonate. Method for producing a catalyst for pyrolysis of hydrocarbon steam, characterized in that. 8. The method of claim 6 or 7, wherein step (a) further comprises a metal compound comprising at least one member selected from the group consisting of Ti, Nb, Mo, V, Co, Ni, W, Fe and rare earth metals. Method for producing a hydrocarbon steam pyrolysis catalyst, characterized in that the step of preparing an aqueous solution. 15. The method of claim 14, wherein step (a) further comprises adding a metal compound containing Ti to prepare an aqueous solution. The group of claim 6 or 7, wherein the Cr-comprising compound, Zr-comprising compound or Cr-Zr-comprising compound of step (a) is composed of Ti, Nb, Mo, V, Co, Ni, W, Fe and rare earth metals. A method for producing a hydrocarbon steam pyrolysis catalyst, characterized in that the compound further comprises one or more selected from. The method of claim 16, wherein the Cr-containing compound, Zr-containing compound or Cr-Zr-containing compound of step (a) is a compound further comprising Ti. The method of claim 6 or 7, wherein the calcining of step (d) is performed for 4 to 24 hours at a temperature of 750 to 1600 ° C. 8. The method of claim 6, wherein the calcining of step (g) is performed for 4 to 24 hours at a temperature of 800 to 1200 ° C. 9. The method of claim 6, wherein the sintering of step (e) is carried out for 2 to 24 hours at a temperature of 800 to 2000 ° C. The method of claim 7, wherein the sintering of step (e) or step (i) is carried out at a temperature of 800 to 2000 ° C. for 2 to 24 hours. A method for producing an olefin, wherein the hydrocarbon is steam pyrolyzed in the presence of the catalyst for hydrocarbon steam pyrolysis of claim 1. 23. The method according to claim 22, wherein the pyrolysis of hydrocarbon steam has a reaction temperature of 600 to 1000 ° C, a weight ratio of water vapor / hydrocarbon to 0.3 to 1.0, and a space velocity (LHSV) of 1 to 20 hr ⁻¹ . Manufacturing method. 24. The process of claim 23, wherein the hydrocarbon steam pyrolysis product has an ethylene / propylene ratio of 1.5 to 1.7. 23. The process of claim 22, wherein steam pyrolysis is carried out by a reactor selected from the group consisting of a fixed bed reactor, a fluidized bed reactor, and a mobile bed reactor.