Patent Application
20250196112
The present invention relates to a catalyst for preparing (meth)acrylic acid and a method for preparing a catalyst for preparing (meth)acrylic acid.
Generally, as the process of preparing (meth)acrylic acid, gas-phase contact oxidization methods of propylene, isobutylene, tertiary butanol, and the like with molecular oxygen in a multitubular fixed bed reactor in which a catalyst layer is present have been used. Since the reaction is an exothermic reaction, various methods such as limiting the thickness of a catalyst layer and using a supported catalyst in which a catalytically active material is supported on a carrier have been applied in order to minimize the increase in temperature during the reaction.
As is known, a method of performing heat treatment is applied to the preparation of the supported catalyst by dispersing a catalytically active material or catalyst precursor in a solvent to obtain a uniform solution or slurry, and then spraying or impregnating the uniform solution or slurry to a carrier or coating the carrier with a powder. Further, to the preparation of an extruded catalyst, a method of dispersing a catalytically active material or catalyst precursor in a solvent to obtain a uniform solution or slurry, then drying the uniform solution or slurry using a drier, pulverizing the dried material using a pulverizer to prepare a powder, adding a molding additive to the powder, and then performing extrusion molding is applied. The extruded catalyst is subjected to a firing process, which is an additional heat treatment, to prepare a final catalyst.
In this case, the firing process is generally performed through a primary firing process and a secondary firing process. In this case, since it takes a long time to perform the firing process, there have been problems in that productivity is decreased and equipment for the firing process becomes complicated.
Therefore, there is a continuing need for research to improve the firing process.
[Citation List] (Patent Document 1) Korean Patent Application Laid-Open No. 10-2014-0138081
The present invention has been made in an effort to provide a method for preparing a catalyst for preparing (meth)acrylic acid with an improved firing process, and a catalyst for preparing (meth)acrylic acid prepared using the same.
An exemplary embodiment of the present invention provides a method for preparing a catalyst represented by the following Chemical Formula 1 for preparing (meth)acrylic acid, the method including: preparing a first solution including a molybdenum precursor and a vanadium precursor; preparing a second solution including a precursor including an M2 element and a precursor including an M4 element; preparing a catalyst suspension by mixing the first solution and the second solution; preparing a slurry by stirring and reacting the catalyst suspension; drying the slurry; pulverizing the dried slurry, and then adding a molding additive and molding the resulting mixture; and firing the molded catalyst according to the following Equation 1 while supplying a mixed gas including air and nitrogen (N2).
In addition, an exemplary embodiment of the present invention provides a catalyst for preparing (meth)acrylic acid, which is prepared by the method for preparing a catalyst represented by the following Chemical Formula 1 for preparing (meth)acrylic acid, in which the catalyst satisfies the following Chemical Formula 1.
MoaVbPcM1dM2eM3fM4gM5hM6iOj [Chemical Formula 1]
In Chemical Formula 1, Mo is molybdenum, V is vanadium, P is phosphorus, and O is oxygen,
The method for preparing a catalyst for preparing (meth)acrylic acid according to the present invention can simplify and automate the process of preparing a catalyst by performing only one firing process without dividing the firing process into a primary firing process and a secondary firing process, and reduce investment costs by downsizing the equipment according to the preparation process.
Furthermore, since only one firing process is performed, the process of preparing a catalyst can be installed in a smaller space, and since the equipment can be downsized, the risks of the preparation process, such as the risk of leakage of chemicals and the risk of fire and explosion, can be reduced.
Finally, the method for preparing a catalyst for preparing (meth)acrylic acid according to the present invention can provide an excellent catalyst for preparing (meth)acrylic acid, which has a high conversion rate of (meth)acrolein and a high selectivity for (meth)acrylic acid.
Hereinafter, the present invention will be described in detail such that a person skilled in the art to which the present invention pertains can easily carry out the present invention. However, the present invention may be implemented in various different forms, and is not limited to the configurations described herein.
When one part “includes” one constituent element in the present specification, unless otherwise specifically described, this does not mean that another constituent element is excluded, but means that another constituent element may be further included.
In the present specification, ‘p to q’ means ‘p or more and q or less’.
In the present specification, the ‘metal precursor’ or ‘precursor including an Mk element” means a material which enables the preparation of a catalyst for preparing (meth)acrylic acid through a chemical reaction as a chemical including the metal or Mk element, respectively. For example, when the metal is molybdenum, the above term is defined as a molybdenum precursor, and in this case, the molybdenum precursor means a material capable of preparing a catalyst for preparing (meth)acrylic acid through a chemical reaction as a chemical including molybdenum.
In the present specification, the notation of elements may be described based on the periodic table.
Further, in describing the present invention, detailed descriptions of related known techniques that may unnecessarily obscure the gist of the present invention will be omitted.
An exemplary embodiment of the present invention provides a method for preparing a catalyst for preparing (meth)acrylic acid represented by the following Chemical Formula 1, the method including: preparing a first solution including a molybdenum precursor and a vanadium precursor; preparing a second solution including a precursor including an M2 element and a precursor including an M4 element; preparing a catalyst suspension by mixing the first solution and the second solution; preparing a slurry by stirring and reacting the catalyst suspension; drying the slurry; pulverizing the dried slurry, and then adding a molding additive and molding the resulting mixture; and firing the molded catalyst according to the following Equation 1 while supplying a mixed gas including air and nitrogen (N2).
MoaVbPcM1dM2eM3fM4gM5hM6iOj [Chemical Formula 1]
In Chemical Formula 1, Mo is molybdenum, V is vanadium, P is phosphorus, and O is oxygen,
In Equation 1,
In the present specification, the unit of the flow rate may be represented by L/min, and the A/B may be represented by a flow rate per gram of catalyst (L/min).
The method for preparing a catalyst for preparing (meth)acrylic acid according to the present invention can simplify and automate the process of preparing a catalyst by performing only one firing process, and can downsize the required equipment. Since the equipment may be downsized described above, the preparation process risk such as the leakage of chemicals and the risk of fire and explosion may be reduced. In addition, the method for preparing a catalyst for preparing (meth)acrylic acid according to the present invention may provide an excellent catalyst for preparing (meth)acrylic acid, the catalyst having a high conversion rate of (meth)acrolein and a high selectivity for (meth)acrylic acid.
Furthermore, Equation 1 may be 0.1 Lmin−1g−1≤A/B≤5 Lmin−1g−1, preferably 0.2 Lmin−1g−1≤A/B≤4.5 Lmin−1g−1. When Equation 1 is satisfied, a catalyst for preparing (meth)acrylic acid may be prepared more efficiently.
In the present invention, when the catalyst suspension is prepared, an acid such as nitric acid (HNO3) may be added as a co-precipitant, a pore-forming agent, and/or a pH adjuster.
According to an exemplary embodiment of the present invention, Chemical Formula 1 may be represented by the following Chemical Formula 2. Specifically, the following Chemical Formula 2 may represent the composition ratio of elements except for oxygen.
Mo12V0.5Cs1.5Cu0.2P1.3Sb0.2 [Chemical Formula 2]
In an exemplary embodiment of the present invention, the preparing of the first solution including the molybdenum precursor and the vanadium precursor may include dissolving the molybdenum precursor and the vanadium precursor in a first solvent. In this case, it is possible to further include heating the first solvent.
In an exemplary embodiment of the present invention, the molybdenum precursor may be included in an amount of 10 parts by weight to 35 parts by weight, preferably 15 parts by weight to 25 parts by weight, based on 100 parts by weight of the first solution.
In an exemplary embodiment of the present invention, the vanadium precursor may be included in an amount of 0.5 parts by weight to 3 parts by weight, preferably 0.5 parts by weight to 2 parts by weight, based on 100 parts by weight of the first solution.
In an exemplary embodiment of the present invention, the first solvent may be water (H2O).
In an exemplary embodiment of the present invention, the molybdenum precursor is preferably a salt soluble in water, nitric acid, and the like, and may be more preferably an ammonium salt, ammonium paramolybdate ((NH4)6Mo7O24), or an oxide, molybdenum trioxide (MoO3), but is not limited thereto. The molybdenum precursor may be a hydrate of the salt.
In an exemplary embodiment of the present invention, the vanadium precursor is preferably a salt soluble in water, nitric acid, and the like, and may be more preferably an ammonium salt, ammonium metavanadate (NH4VO3), or an oxide, vanadium pentoxide (V2O5), but is not limited thereto. The vanadium precursor may be a hydrate of the salt.
In an exemplary embodiment of the present invention, the preparing of the second solution including the precursor including the M2 element and the precursor including the M4 element may include dissolving the precursor including the M2 element and the precursor including the M4 element in a second solvent. In this case, it is possible to further include heating the second solvent.
In an exemplary embodiment of the present invention, the precursor including the M2 element may be included in an amount of 0.5 parts by weight to 5 parts by weight, preferably 1 part by weight to 3.5 parts by weight, based on 100 parts by weight of the second solution.
In an exemplary embodiment of the present invention, the precursor including the M4 element may be included in an amount of 5 parts by weight to 40 parts by weight, preferably 10 parts by weight to 25 parts by weight, based on 100 parts by weight of the second solution.
In an exemplary embodiment of the present invention, the second solvent may be one or more selected from the group consisting of water, phosphoric acid, and nitric acid, or a mixture thereof.
In an exemplary embodiment of the present invention, the precursor including the M2 element may be a copper precursor. That is, M2 may be Cu.
In an exemplary embodiment of the present invention, the copper precursor is preferably a salt soluble in water, nitric acid, phosphoric acid, and the like, and may be more preferably a nitrate, copper nitrate (Cu(NO3)2), or a carbonate, copper carbonate dihydroxide (Cu2(OH)2CO3), but is not limited thereto. The copper precursor may be a hydrate of the salt.
In an exemplary embodiment of the present invention, the precursor including the M6 element may be a cesium precursor. That is, M6 may be Cs.
In an exemplary embodiment of the present invention, the cesium precursor is preferably a salt soluble in water, nitric acid, phosphoric acid, and the like, and may be more preferably a nitrate, cesium nitrate (CsNO3), or a carbonate, cesium carbonate (Cs2CO3), but is not limited thereto. The cesium precursor may be a hydrate of the salt.
In an exemplary embodiment of the present invention, the preparing of the catalyst suspension by mixing the first solution and the second solution may include: cooling the first solution; and adding the second solution to the cooled first solution. The cooling of the first solution is to lower the temperature that increased during the process of preparing the first solution while heating the first solvent, and in this case, the temperature of the first solution may be cooled to about 60° C.
In an exemplary embodiment of the present invention, the preparing of the slurry by stirring and reacting the catalyst suspension may include: primarily stirring the catalyst suspension; adding an antimony precursor to the first stirred catalyst suspension; and secondarily stirring the catalyst suspension to which the antimony precursor is added.
In an exemplary embodiment of the present invention, the antimony precursor may be antimony trioxide (Sb2O3), more specifically a hydrate of antimony trioxide, but is not limited thereto.
In an exemplary embodiment of the present invention, the primarily stirring of the catalyst suspension may be performed for 15 minutes or more, 240 minutes or less, or 30 minutes or more and 120 minutes or less, but the duration is not limited thereto.
In an exemplary embodiment of the present invention, the secondarily stirring of the catalyst suspension may be performed for 1 hour or more, 48 hours or less, or preferably 5 hours or more and 24 hours or less.
That is, the time taken for the secondarily stirring of the catalyst suspension is longer than the time taken for the primarily stirring of the catalyst suspension.
In an exemplary embodiment of the present invention, the drying of the slurry may be performed at 100° C. or higher, 300° C. or less, preferably 100° C. or higher, and 250° C. or less. Further, the drying may be performed by any method in the related art, which is used in the art, for example, evaporative drying, atomization (spray) drying, drum drying, flash drying, and the like.
In an exemplary embodiment of the present invention, the molding additive may be those including an inorganic fiber and a pore-forming agent. As the pore-forming agent, ammonium nitrate may be used, but the pore-forming agent is not limited thereto.
In an exemplary embodiment of the present invention, the pulverizing of the dried slurry, and then the adding of the molding additive and the molding of the resulting mixture may include: preparing a mixture in which a molding additive, water, and alcohol are mixed after pulverizing the dried slurry; and molding the mixture. In this case, the molding of the mixture may be performed using a continuous extruder, but is not limited thereto.
In an exemplary embodiment of the present invention, the nitrogen in the mixed gas is present in gaseous form. Thus, the nitrogen in the mixed gas is described as N2, which is in molecular form.
In an exemplary embodiment of the present invention, the volume of nitrogen in the mixed gas may be 1.5-fold to 30-fold, preferably 1.5-fold to 25-fold of the volume of air. When the volume proportion is satisfied, a catalyst for preparing (meth)acrylic acid may be prepared more efficiently.
In an exemplary embodiment of the present invention, the firing of the molded catalyst while supplying the mixed gas including air and nitrogen may be performed at a temperature of 300° C. to 600° C., preferably 350° C. to 550° C.
In an exemplary embodiment of the present invention, the mixed gas may further include water, and the water in the mixed gas may be included in an amount of 0.5 wt % to 15 wt %, preferably 1 wt % to 12 wt %, based on the total weight of the mixed gas. The content of the water means the content of water measured when the mixed gas is in a constant temperature bath at 5° C. to 50° C.
An exemplary embodiment of the present invention provides a catalyst for preparing (meth)acrylic acid, which is prepared by the method for preparing the catalyst for preparing (meth)acrylic acid of the present invention, in which the catalyst satisfies Chemical Formula 1. The catalyst for preparing (meth)acrylic acid, which is prepared by the method for preparing a catalyst for preparing (meth)acrylic acid according to the present invention, has a high conversion rate of (meth)acrolein, high selectivity for (meth)acrylic acid, and excellent performance.
An exemplary embodiment of the present invention provides a method for preparing (meth)acrylic acid, which prepares (meth)acrylic acid using the catalyst for preparing (meth)acrylic acid. Specifically, the method for preparing (meth)acrylic acid may prepare (meth)acrylic acid by filling a fixed-bed reactor with the catalyst for preparing (meth)acrylic acid, and performing the (meth)acrolein oxidation reaction while supplying (meth)acrolein.
In an exemplary embodiment of the present invention, the (meth)acrolein may be supplied at a space velocity of 5 hr−1 to 100 hr−1.
In an exemplary embodiment of the present invention, the (meth)acrolein oxidation reaction may be performed at a temperature of 300° C. or higher.
The fixed-bed reactor applied to the method for preparing (meth)acrylic acid according to the present invention includes: a first catalyst layer filled with a front catalyst for preparing (meth)acrolein using propylene, isobutylene, or a mixture thereof as a raw material; a second catalyst layer filled with a rear catalyst for preparing (meth)acrylic acid using the (meth)acrolein as a raw material; and an inert material layer including an inert material between the first catalyst layer and the second catalyst layer.
Preferably, a known fixed-based reactor may be used as the fixed-bed reactor. Further, preferably, the fixed-bed phase reactor may be a fixed-bed multitubular reactor including a plurality of reaction tubes each including the first catalyst layer, the second catalyst layer, and the inert material layer.
Examples of the fixed-bed reactor include a fixed-bed reactor composed of one reactor equipped with a first-stage reaction zone (or front reaction zone) filled with the front catalyst and a second-stage reaction zone (or rear reaction zone) filled with the rear catalyst. In this case, the first-stage reaction zone corresponds to the first catalyst layer, the second stage reaction zone corresponds to the second catalyst layer, and the inert material layer is provided between the first-stage reaction zone and the second-stage reaction zone. That is, at least three layers composed of the first catalyst layer, the inert material layer, and the second catalyst layer are provided in one reaction tube.
As the fixed-bed reactor, a fixed-bed reactor composed of two reactors: a front reactor equipped with a reaction tube filled with the front catalyst and a rear reactor equipped with a reaction tube filled with the rear catalyst may also be used. In this case, the portion of the front reactor filled with the front catalyst corresponds to the first catalyst layer, and the portion of the rear reactor filled with the rear catalyst corresponds to the second catalyst layer. The inert material layer may be installed on the outlet side (the side from which gas is discharged in the reactor) rather than the first catalyst layer in the front reactor, or on the inlet side (the side into which the gas is introduced in the reactor) than the second catalyst layer in the rear reactor, or may be installed in a tube connecting the front reactor and the rear reactor.
As the reaction tube provided in the fixed-bed reactor, a typical reaction tube having a circular cross-sectional shape may be used. The inner diameter and length of the reaction tube may be determined within a range that allows the reaction tube to be filled with a catalyst and an inert material, and to exhibit an appropriate reaction efficiency. Preferably, the reaction tube may have an inner diameter of 15 mm to 100 mm and a length of 1 m to 10 m.
The front catalyst may convert propylene, isobutylene, or a mixture thereof into (meth)acrolein by the contact gas phase oxidation of propylene, isobutylene, or a mixture thereof, and the catalyst for preparing (meth)acrylic acid according to the present invention may be used as the front catalyst.
The rear catalyst may convert (meth)acrolein obtained from the first catalyst layer into (meth)acrylic acid by the contact gas phase oxidation of the (meth)acrolein, and the catalyst for preparing (meth)acrylic acid according to the present invention may be used.
In an exemplary embodiment of the present invention, the catalyst for preparing (meth)acrylic acid according to the present invention may be used as the front catalyst, and a known oxide catalyst may be used as the rear catalyst.
In an exemplary embodiment of the present invention, a known oxide catalyst may be used as the front catalyst, and the catalyst for preparing (meth)acrylic acid according to the present invention may be used as the rear catalyst.
In an exemplary embodiment of the present invention, the catalyst for preparing (meth)acrylic acid according to the present invention may be used as the front catalyst and the rear catalyst, respectively.
The front catalyst and the rear catalyst may each include an inert support along with the active component.
The composition of the material for the inert carrier is not particularly limited as long as it does not inhibit the activity of the catalyst. For example, the inert carrier may be one or more compounds selected from the group consisting of SiO2, Al2O3, MgO, MgCl2, CaCl2), ZrO2, TiO2, B2O3, CaO, ZnO, BaO, ThO2, SiO2—Al2O3, SiO2—MgO, SiO2—TiC2, SiO2—V2O5, SiO2—CrO2O3, SiO2—TiO2—MgO, and zeolite.
The front catalyst and the rear catalyst may each be prepared by a typical method in the art to which the present invention pertains.
For example, the catalysts may be prepared using an extrusion molding method, a tablet molding method, and the like, in which catalyst constituent components including the active component are molded into a predetermined shape. In addition, the catalyst may be prepared by a supporting method in which the active component is supported on any inert carrier.
The shape of the catalysts is not particularly limited, and may be spherical, cylindrical, ring-shaped, or amorphous.
The first catalyst layer is filled with the front catalyst, and the second catalyst layer is filled with the rear catalyst.
As the front catalyst and the rear catalyst, a single type of catalyst may be each used, or multiple types of catalysts with different activities or configurations may be used.
Meanwhile, the inert material layer is filled between the first catalyst layer and the second catalyst layer. The inert material may be a material that exhibits substantially no activity against a (meth)acrolein-containing reaction gas and has heat resistance at above a temperature at which the reaction is performed. Preferably, the material for the inert material may be stainless steel.
In an exemplary embodiment of the present application, as the method for preparing (meth)acrylic acid, it is possible to apply a typically used method for preparing (meth)acrylic acid, except for using the catalyst for preparing (meth)acrylic acid of the present application.
Hereinafter, the present application will be described in detail with reference to Examples for specifically describing the present application. However, the Examples according to the present application may be modified in various forms, and it is not interpreted that the scope of the present application is limited to the Examples described in detail below. The Examples of the present application are provided for more completely explaining the present application to the person with ordinary skill in the art.
A first solution was prepared by putting 1000 ml of distilled water into a 5 L reactor equipped with a stirrer and dissolving 300 g of (NH4)6Mo7O24·4H2O and 10 g of NH4VO3·4H2O.
Apart from this, a second solution was prepared by adding 50 g of CsNO3, 8 g of Cu(NO3)2, 20 g of H3PO4, and 50 g of HNO3 to 100 ml of high-temperature distilled water and mixing the resulting mixture. After the first solution was naturally cooled, a catalyst suspension was prepared by mixing the cooled first solution and the second solution. After the catalyst suspension was stirred for 15 minutes, a slurry was prepared by adding 3 g of Sb2O3 to the catalyst suspension and further stirring the resulting mixture at room temperature (20° C. to 25° C.) for 24 hours.
Thereafter, the slurry was added dropwise to a solution supply container of a spray dryer.
Subsequently, a powder with a size of 200 μm or less was obtained by drying the slurry added dropwise to the solution supply container using the spray dryer.
Thereafter, a catalyst was prepared by mixing the powder obtained through the spray dryer, an inorganic fiber as a molding additive, ammonium nitrate as a pore-forming agent, and a mixture of water and alcohol so as to satisfy 59 wt %, 20 wt %, 10 wt %, and 10 wt %, respectively, using a continuous mixer.
A molded catalyst was prepared by extrusion molding the mixed catalyst prepared by mixing the mixture so as to satisfy the above ratio through a continuous extruder.
Finally, a catalyst for preparing (meth)acrylic acid of Example 1 was prepared by heat-treating the molded catalyst at 400° C. for 16 hours in a tubular firing furnace while supplying a firing gas at a total flow rate of 1 L/min per 1 (g) of catalyst. In this case, the firing gas included air and N2, and the volume ratio of air and N2 in the firing gas is as shown in the following Table 1.
The catalysts for preparing (meth)acrylic acid of Examples 2 and 3 were each prepared in the same manner as in Example 1, except that a firing gas satisfying the volume ratio of air and N2 described in the following Table 1 was used.
The catalysts for preparing (meth)acrylic acid of Examples 4 and 5 were each prepared in the same manner as in Example 1, except that a firing gas satisfying the volume ratio of air and N2 described in the following Table 1 and including water in the content described in the following Table 1 was used, and the flow rate was each changed as described in the following Table 1.
A catalyst molded in the same manner as in Example 1 was prepared. Thereafter, the catalyst for preparing (meth)acrylic acid of Comparative Example 1 was prepared in the same manner as in Example 1, except that a firing gas including only N2 without including air as shown in the following Table 1 was used.
A catalyst molded in the same manner as in Example 1 was prepared. Thereafter, primary firing was performed by performing heat treatment at 400° C. for 16 hours while supplying a firing gas including only N2 without including air at a flow rate of 1 L/min per gram of catalyst. After the primary firing, the catalyst for preparing (meth)acrylic acid of Comparative Example 2 was prepared by performing secondary firing during a heat treatment at 400° C. for 12 hours while supplying a firing gas including only air without including N2 at a flow rate of 1 L/min.
In this case, the volume ratios of N2 used in the primary firing and air used in the secondary firing were as shown in the following Table 1.
The catalysts for preparing (meth)acrylic acid of Comparative Examples 3 to 5 were each prepared in the same manner as in Comparative Example 1, except that firing gases including the volume ratio of air or N2 and the content of water described in the following Table 1 were used. That is, in Comparative Examples 3 and 4, the firing gas did not include N2, and in Comparative Example 5, the firing gas did not include air.
A catalyst was prepared as follows.
A first solution was prepared by putting 4000 ml of distilled water into a 5 L reactor equipped with a stirrer and dissolving 300 g of MoO3, 26 g of H3PO4, and 530 g of V2O5.
Apart from this, a second solution was prepared by adding 35 g of CsCO3 to 50 ml of high-temperature distilled water and mixing the resulting mixture. After the first solution was naturally cooled, a catalyst suspension was prepared by mixing the cooled first solution and the second solution. After the catalyst suspension was stirred for 30 minutes, 4 g of Cu2(OH)2CO3 and 5 g of Sb2O3 were added to the catalyst suspension, the resulting mixture was stirred at room temperature (20° C. to 25° C.) for 1 hour, and then 30 g of NH4NO3 was added thereto and the resulting mixture was additionally stirred for 30 minutes to prepare a slurry.
Thereafter, the slurry was added dropwise to a solution supply container of a spray dryer.
Subsequently, a powder of 200 μm or less was obtained by drying the slurry added dropwise to the solution supply container using the spray dryer.
Thereafter, a catalyst was prepared by mixing the powder obtained through the spray dryer, an inorganic fiber as a molding additive, ammonium nitrate as a pore-forming agent, and a mixture of water and alcohol so as to satisfy 62 wt %, 10 wt %, 10 wt %, and 17 wt %, respectively, using a continuous mixer.
A molded catalyst was prepared by extrusion molding the mixed catalyst prepared by mixing the mixture so as to satisfy the above ratio through a continuous extruder.
Finally, the catalyst for preparing (meth)acrylic acid of Comparative Example 6 was prepared by heat-treating the molded catalyst in a tubular firing furnace at 400° C. for 16 hours while supplying a firing gas at a flow rate of 0.08 L/min per gram of catalyst (that is, less than 0.01 Lmin−1g−1 and not satisfying Equation 1). In this case, the firing gas included air and N2, and the volume ratio of air and N2 in the firing gas is as shown in the following Table 1.
A catalyst molded in the same manner as in Example 1 was prepared. Thereafter, the catalyst for preparing (meth)acrylic acid of Comparative Example 7 was prepared by performing primary firing, in which heat treatment was performed at 400° C. for 16 hours while supplying a firing gas including only N2 without including air at a flow rate of 8 L/min per gram of catalyst (that is, more than 5 Lmin−1g−1 and not satisfying Equation 1) as shown in the following Table 1.
A pilot-scale shell-and-tube type fixed bed reactor was prepared, which was composed of a steel reaction tube with an inner diameter of 1 inch and a fixed bed packed section length of 3000 mm, and a shell (diameter 100 mm) that covers the reaction tube and allows a heat medium to flow. The reactor included a front catalyst layer or a rear catalyst layer, the same catalyst was used in the front catalyst layer, and the rear catalyst layer was each filled with the catalysts of Examples 1 to 5 and Comparative Examples 1 to 7. Thereafter, the raw material mixed gas (7.5 vol % raw gas, 14 vol % oxygen, 18 vol % water vapor, and 60.5 vol % inert nitrogen gas) was flowed at a space velocity of 80 hr−1 to perform the reaction at a reaction temperature of 310° C. The conversion rate and selectivity were calculated by comparing the number of moles of each produced material using a gas chromatography analyzer for the gas that passed through the reactor.
As the raw material gas mixture (raw material gas), one of propylene, isobutylene, t-butyl alcohol, and methyl-t-butyl ether, or a mixture thereof may be used, but in this experimental example, an experiment was conducted when the raw material gas included propylene and isobutylene.
Instrument: Agilent 7890B Gas Chromatography system
Column: Molecular sieve 5A 2.1 mm (L.D)*2.0 M 80/100 mesh
Plot Q 2.1 mm (I.D)*2.0 M 80/100 mesh
WAX-DA 0.53 mm (I.D)*30 M*1 μm
Solvent: 1,4-dioxane
Column temperature: measured while increasing the temperature from 50° C. to 200° C.
Moisture content: measured at 120° C. for 10 minutes using an MX-50 moisture content apparatus
Based on the analyzed results, the conversion rate and selectivity yield were calculated and are shown in the following Table 2.
In Table 1, the materials described in the firing step mean the materials which the gases used in each firing step include, and +water means that water is included in the gas. Further, when the firing step was performed only once, the relevant content was described for the primary firing. Accordingly, in Table 1 above, the firing time was described for each firing step, and when the secondary firing step was not performed, the time related to the secondary firing was described as ‘-’. That is, the total firing time can be said to be the time taken for primary firing and secondary firing.
The catalysts used in Table 2 above mean that the rear catalyst layer is filled with the catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 7 as described above.
Referring to the results of Tables 1 and 2, in the method for preparing a catalyst for preparing (meth)acrylic acid of Examples 1 to 5, in which a mixed gas of air and N2 is used simultaneously in one step of firing, it is possible to confirm the effect of improving the performance aspect of the catalyst or shortening the time for preparing the catalyst than in Comparative Examples 1 to 7, in which air or N2 is used alone instead of the mixed gas of air and N2 or the two-step firing is performed.
Specifically, when the catalysts of Comparative Examples 1 and 7, which were fired using only N2 gas, were used, it could be confirmed that under the conditions in which the catalyst preparation time is the same, the yield of (meth)acrylic acid and the selectivity of the yield of (meth)acrylic acid were lower than when the air and N2 firing gas (mixed gas) were used as in Examples 1 to 5. Moreover, when determined together with the results of Comparative Examples 2 and 5, it could be confirmed that using N2 gas alone may have an adverse effect on the yield of (meth)acrylic acid and the selectivity of the yield of (meth)acrylic acid.
In contrast, when the catalysts of Comparative Examples 3 and 4, which were fired using only air gas, were used, it could be confirmed that under the conditions in which the catalyst preparation time is the same, the yield of (meth)acrylic acid and the selectivity of the yield of (meth)acrylic acid were remarkably lower than when the catalysts of Examples 1 to 5 were used. It could be confirmed that the performance is not good enough to be used as a catalyst for preparing (meth)acrylic acid when N2 gas is not used.
Further, from the results of Comparative Example 2, it could be confirmed that the order in which the types of gas used in the primary firing and the gas used in the secondary firing are used may also affect catalyst performance. In contrast, since the method for preparing a catalyst for preparing (meth)acrylic acid according to the present invention uses a mixed gas of air and N2, there is no need to consider the order in which different types of firing gases are introduced. This means that the method for preparing a catalyst for preparing (meth)acrylic acid according to the present invention is more convenient in terms of process.
Furthermore, when compared to Examples 1 to 5 in which the catalyst satisfies Chemical Formula 1 and the flow rate per gram of catalyst satisfies Equation 1, it could be confirmed that even though catalysts satisfying Chemical Formula 1 are used as in Comparative Examples 6 and 7, the performance (conversion rate, selectivity, and/or yield) of the catalyst was poor because the flow rate per gram of catalyst did not match Equation 1 of the present invention.
Additionally, referring to Examples 4 and 5, it could be confirmed that when the air and N2 mixed gas (firing gas) includes water (moisture), it is possible to further increase the yield of (meth)acrylic acid or the selectivity of the yield of (meth)acrylic acid.
That is, as described above, the method for preparing a catalyst for preparing (meth)acrylic acid according to the present invention may prepare a catalyst with excellent performance within a short period of time, meaning that it is easier to increase productivity and simplify equipment in the process of preparing a catalyst.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0008209 | Jan 2023 | KR | national |
| 10-2024-0005265 | Jan 2024 | KR | national |
This application is a National Stage Application of International Application No. PCT/KR2024/000673 filed on Jan. 15, 2024, which claims priority to and the benefit of Korean Patent Application Nos. 10-2023-0008209 and 10-2024-0005265 filed in the Korean Intellectual Property Office on Jan. 19, 2023 and Jan. 12, 2024, respectively, the entire contents of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2024/000673 | 1/15/2024 | WO |
