Carrier and manufacturing method of a catalyst containing uniformly distributed titanium dioxide

Abstract

To provide a catalyst support comprising at least homogeneously distributed titanium dioxide and alumina.SOLUTION: A calcined catalyst support comprises an alumina support coated with 1 and 5 wt.% TiO2 in relation to the alumina support (Al2O3), TiO2 being homogeneously dispersed on the alumina support. Consequently, a surface coating is formed on the alumina support. The surface coating includes the coating over the surfaces of the alumina support's inner pore walls, but does not include the coating within the bulk of the alumina support.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing a catalyst support containing at least uniformly distributed titanium dioxide and alumina, and a catalyst support prepared by the method.

Background Art

[0002] Patent Document 1 describes a method of introducing a titanium compound into a catalyst support material by impregnation. Using a liquid medium suitable for impregnation can bring about contact between the titanium compound and the catalyst support material. In the examples of Patent Document 1, the use of ethanol is disclosed as a liquid medium of an organic substance that brings the catalyst support material into contact with the titanium compound while preparing a catalyst support modified with the titanium compound. Further, Patent Document 1 discloses that although not exemplified, an inorganic liquid medium such as water can be used to bring the catalyst support material into contact with the titanium compound.

[0003] Patent Document 2 discloses a method of preparing an aqueous composition of a carboxylic acid and a titanium compound and simultaneously adding it to a catalyst support material, that is, a method of making a mixture of the titanium compound and the carboxylic acid to be added to the catalyst support material.

[0004] Patent Document 3 discloses a uniform and amorphous catalyst support containing a modified metal oxide and a base metal oxide in which the modified metal oxide is uniformly distributed throughout the base metal oxide. Patent Document 3 describes a precipitation step using an alumina salt as a raw material for producing modified alumina.

[0005] Either the prior art preparation methods do not match, or a catalyst is obtained in which the titanium compound is not uniformly dispersed on the catalyst support. Therefore, it is necessary to improve the above-mentioned methods.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Means for Solving the Problems

[0007] As a first aspect in the present application, a method for preparing a catalyst support is provided, and the method includes: i) a step of preparing an alumina suspension having a pH of 6 to 8 and containing alumina selected from the group consisting of transition alumina, boehmite, and mixtures thereof, preferably γ-alumina; ii) a step of preparing a solution of a titanium compound; iii) a step of adding an acid to the alumina suspension until the pH of the alumina suspension becomes 4 to 5 to form an acid-modified alumina suspension; iv) a step of adding a titanium compound to the acid-modified alumina suspension to form an alumina / titanium compound.

[0008] The method may further include a step of adding an acid to the suspension of the alumina / titanium compound to form an acid-modified suspension of the alumina / titanium compound.

[0009] The method may further include a step of heating the suspension of the alumina / titanium compound or the acid-modified suspension of the alumina / titanium compound to form a heated suspension of the alumina / titanium compound or a heated suspension of the acid-modified alumina / titanium compound. The heating is carried out at a temperature range of 30°C to 70°C, typically about 50°C, for 2 to 4 hours.

[0010] The method may include a step of drying the heated suspension of the alumina / titanium compound or the heated suspension of the acid-modified alumina / titanium compound.

[0011] The method can include a step of drying the acid-modified alumina suspension to form a dry mixture of acid-modified alumina before adding the solution of the titanium compound.

[0012] According to a first option for the first aspect of the present application, a method for preparing a catalyst support is provided, the method comprising: i) preparing an alumina suspension comprising alumina having a pH of 6 to 8 and selected from the group consisting of transition alumina, boehmite, and mixtures thereof, preferably γ-alumina; ii) preparing a solution of a titanium compound; iii) adding an acid to the alumina suspension until the pH of the alumina suspension reaches 4 to 5 to form an acid-modified alumina suspension; iv) adding the solution of the titanium compound to the acid-modified alumina suspension to form an alumina / titanium compound suspension; v) drying the alumina / titanium compound suspension to form a dry mixture of alumina / titanium compound.

[0013] According to a second option for the first aspect of the present application, a method for preparing a catalyst support is provided, the method comprising: i) preparing an alumina suspension comprising alumina having a pH of 6 to 8 and selected from the group consisting of transition alumina, boehmite, and mixtures thereof, preferably γ-alumina; ii) preparing a solution of a titanium compound; iii) adding an acid to the alumina suspension until the pH of the alumina suspension reaches 4 to 5 to form an acid-modified alumina suspension; iv) adding the solution of the titanium compound to the acid-modified alumina suspension to form an alumina / titanium compound suspension; v) adding an acid to the alumina / titanium compound suspension to form an acid-modified alumina / titanium compound suspension; (vi) drying the suspension of the acid-modified alumina / titanium compound to form a dried mixture of the pH-modified alumina / titanium compound.

[0014] The first and second options for the first aspect of the present application may further include heating the suspension of the alumina / titanium compound or the acid-modified alumina / titanium suspension. The heating is carried out in a temperature range of 30°C to 70°C, typically at about 50°C, preferably for 2 to 4 hours.

[0015] If the method of the first aspect of the present application does not include the step of drying the acid-modified alumina suspension before adding the solution of the titanium compound, the acid added to the alumina suspension is preferably formic acid, lactic acid, citric acid, or a mixture thereof, more preferably lactic acid, citric acid, or a mixture thereof, and most preferably citric acid.

[0016] The proportion of the acid added to the alumina suspension can be 5 to 30% by weight of the acid-modified alumina suspension, preferably 5 to 20% by weight of the acid-modified alumina suspension. However, it will be understood that the amount of acid added must be sufficient to lower the pH of the alumina suspension from a pH of 6 to 8 to a pH of 4 to 5.

[0017] According to the third option for the first aspect of the present application, a method for preparing a catalyst support is provided, the method comprising: i) preparing an alumina suspension comprising alumina having a pH of 6 to 8 and selected from the group consisting of transition alumina, boehmite, and mixtures thereof, preferably γ-alumina; ii) preparing a solution of a titanium compound; iii) adding an acid to the alumina suspension until the pH of the alumina suspension reaches 4 to 5 to form an acid-modified alumina suspension; iv) drying the acid-modified alumina suspension to form a dried mixture of the acid-modified alumina; v) adding the solution of the titanium compound to the dried mixture of the acid-modified alumina to form a suspension of the alumina / titanium compound; (vi) drying the suspension of the alumina / titanium compound to form a dried alumina / titanium compound mixture.

[0018] According to a fourth option for the first aspect of the present application, a method for preparing a catalyst support is provided, the method comprising: (i) preparing an alumina suspension comprising alumina having a pH of 6 to 8 and selected from the group consisting of transition alumina, boehmite, and mixtures thereof, preferably γ-alumina; (ii) preparing a solution of a titanium compound; (iii) adding an acid to the alumina suspension until the pH of the alumina suspension reaches 4 to 5 to form an acid-modified alumina suspension; (iv) drying the acid-modified alumina suspension to form a dried mixture of the acid-modified alumina; (v) adding the solution of the titanium compound to the dried mixture of the acid-modified alumina to form a suspension of the alumina / titanium compound; (vi) adding an acid to the suspension of the alumina / titanium compound to form an acid-modified suspension of the alumina / titanium compound; (vii) drying the acid-modified suspension of the alumina / titanium compound to form a dried mixture of the acid-modified alumina / titanium compound.

[0019] The third and fourth options for the first aspect of the present application may further include a step of heating the suspension of the alumina / titanium compound or the acid-modified suspension of the alumina / titanium compound. The heating is carried out in a temperature range of 30°C to 70°C, typically about 50°C, and preferably for 2 to 4 hours.

[0020] It will be understood that the amount of acid added in step (vi) of the fourth option of the first aspect of the present application is an amount sufficient to ensure that the pH of the suspension of the alumina / titanium compound is maintained at a pH of 4 to 5.

[0021] When the method of the first aspect of the present application includes a step of drying the acid-modified alumina suspension before adding the solution of the titanium compound, the acid to be added is preferably a carboxylic acid containing formic acid, lactic acid, citric acid, or a mixture thereof (an organic compound containing at least one carboxyl group (C(=O)OH)).

[0022] The proportion of the acid added to the alumina suspension is 5 to 30% by weight of the acid-modified alumina suspension, preferably 5 to 20% by weight of the acid-modified alumina suspension. However, it will be understood that the amount of acid added must be sufficient to lower the pH of the alumina suspension from a pH of 6 to 8 to a pH of 4 to 5.

[0023] As in the third and fourth options for the first aspect of the present application, rather than drying the acid-modified alumina suspension before adding the solution of the titanium compound (known as the incipient wetness (IW) method), for example, as in the first and second options of the first aspect of the present invention, it is preferred not to dry the acid-modified alumina suspension before adding the solution of the titanium compound (known as the equilibrium deposition filtration (EDF)).

[0024] The method (and options) of the first aspect of the present application can include a final step of firing the dry alumina / titanium compound mixture or the dry mixture of the acid-modified alumina / titanium compound. The firing is typically carried out at a temperature of 100°C to 1000°C, preferably 400°C to 600°C, each preferably for 2 to 5 hours, to produce a carrier for the fired catalyst.

[0025] The transition alumina is preferably γ (gamma)-alumina, δ (delta)-alumina, θ (theta)-alumina, or a mixture thereof. Most preferably, the transition alumina is γ-alumina.

[0026] The alumina suspension is preferably prepared by suspending at least alumina selected from the group consisting of transition alumina, boehmite, and mixtures thereof, preferably γ-alumina, in water. The proportion of alumina in the suspension is 5 to 60% based on the total alumina suspension, preferably 40 to 50% based on the total alumina suspension.

[0027] Preferably, the alumina in the alumina suspension is only alumina selected from the group consisting of transition alumina, boehmite, and mixtures thereof, preferably only γ-alumina.

[0028] The solution of the titanium compound is prepared by dissolving a titanium precursor in at least water. A water-soluble titanium precursor containing potassium titanate oxalate, ammonium titanate oxalate, ammonium titanate lactate, or a mixture thereof can be used. Optionally, the temperature of at least the water can be raised to 90 °C to accelerate the dissolution process. The concentration of the titanium precursor in the solution should be as high as possible and limited only by the solubility of the titanium precursor in water. A preferred titanium solution is an aqueous solution of potassium titanate oxalate dehydrate produced at 1% to 4% by weight calculated as TiO2. The titanium solution can be magnetically stirred for about 30 minutes before being added to the alumina suspension. The titanium solution is preferably passed through an ion exchange column to remove any impurities, such as potassium, before being added to the alumina suspension. Therefore, the titanium solution is preferably magnetically stirred for a certain period of time and (separately) passed through an ion exchange column before being added to the alumina suspension.

[0029] Any drying method known in the technical field of the present application can be used in the method of the present invention. Drying is typically carried out at a temperature of 80 °C to 120 °C for 0.5 to 5 hours.

[0030] The suspension of the alumina / titanium compound contains 99 to 95% by weight, most preferably 97 to 99% by weight, of alumina calculated as Al2O3 and preferably 1 to 5% by weight, most preferably 1 to 3% by weight, of the titanium compound calculated as TiO2, based on the total of the alumina calculated as Al2O3 and the titanium compound calculated as TiO2.

[0031] The dry mixture of the alumina / titanium compound (including the acid / pH-modified alumina / titanium compound) contains 99 to 95% by weight, most preferably 99 to 97% by weight, of alumina calculated as Al2O3 and preferably 1 to 5% by weight, most preferably 1 to 3% by weight, of the titanium compound calculated as TiO2, based on the total of the dry mixture of the alumina / titanium compound (including the acid / pH-modified alumina / titanium compound).

[0032] According to the second aspect of the present application, there is provided a carrier of the catalyst prepared according to the first aspect of the present invention.

[0033] According to the present invention, there is provided a fired catalyst carrier including an alumina carrier (Al2O3) coated with 1 to 5% by weight of TiO2, wherein TiO2 is uniformly dispersed on the alumina carrier.

[0034] "Coat / coated" means a surface coating formed over the material of the carrier and includes the coating of the surface of the inner pore walls of the material of the carrier (excluding the inside of the bulk of the carrier).

[0035] The catalyst preferably includes an alumina carrier coated with 3 to 5% by weight (measured after firing) of TiO2 with respect to the alumina carrier (Al2O3).

[0036] The weight percentage of TiO2 in the carrier of the catalyst prepared according to the first aspect of the present invention is expressed in terms of the total weight of the carrier of the catalyst.

[0037] When the alumina suspension is first treated with an acid, it has been found most surprisingly that an improvement in the uniform distribution of the titanium compound on the support of the alumina catalyst is achieved before the alumina suspension is brought into contact with the solution of the titanium compound.

[0038] According to a fourth aspect of the present application, there is provided a method for preparing a support for a promoted catalyst, the method comprising: i) a step of preparing a support for a catalyst according to the first aspect of the present invention; ii) a step of obtaining a support for a promoted catalyst by introducing a promoter onto and / or into the support for the catalyst; and

[0039] The promoter is preferably a manganese compound containing, for example, manganese hydroxide, manganese oxide, and / or manganese oxyhydroxide. Manganese may be added to the support for the catalyst together with the solution of the titanium compound, that is, by mixing a manganese precursor, such as manganese acetate, with the solution of the titanium compound in step ii) of the first aspect of the present invention. Alternatively, the calcined support for the catalyst may be impregnated with a manganese precursor, such as manganese acetate.

[0040] The fourth aspect of the present application may include a final step of calcination.

[0041] The support for the catalyst or the support for the promoted catalyst prepared according to the present invention can be used in, for example, a Fischer-Tropsch catalyst, a hydrocarbon synthesis catalyst, a hydrodesulfurization catalyst, a hydrogenation treatment catalyst, and a photocatalyst for NO oxidation.

[0042] The present invention will be described in more detail herein by the accompanying drawings and the following non-limiting examples.

Brief Description of the Drawings

[0043]

Figure 1

Figure 2

Best Mode for Carrying Out the Invention

[0044] [Experiment] The titanium(IV) bis(ammonium lactato) dihydroxide (TALH) used is an aqueous solution of 1 wt% TALH (calculated as TiO₂), known to those skilled in the art as Tyzor® LA.

[0045] In the following examples, the weight percentage of Ti calculated as TiO₂ in the catalyst support is expressed in terms of the total weight of the catalyst support.

[0046] X-ray photoelectron spectroscopy (XPS) was used in the following examples to determine the TiO₂ distribution on the alumina surface. XPS is a surface-sensitive quantitative spectroscopy technique that measures the elemental composition in terms of parts per thousand. Since XPS is only surface-sensitive, both the as-received (current particles) and the material after grinding (pulverization) using a pestle and mortar were analyzed by XPS and the elemental ratios were reported. In the grinding process where just enough force was applied using a pestle and mortar to break down the particles, approximately the same amount of sample was used as (the sample when measuring the current particles).

[0047] The XPS spectra were recorded on a KRATOS Axis Ultra DLD, and the analyzer was operated at a fixed pass energy of 160 eV for spectral survey and 20 eV for individual regions. The measurements were carried out using a monochromatic AlKα light source. Due to the nature of the material, charge neutralization was required during acquisition. All spectra were energy-corrected using C1s at 284.6 eV. All samples were encapsulated as free powders in a molybdenum sample holder. For all carrier samples in the examples, the peak area ratios as determined by XPS, along with the calculated differences between the current particles and the ground samples, are provided in Tables 1, 2, and 3. As this difference increases, the uniformity of the sample decreases. A uniform sample shows a very small or negative value.

[0048] [Examples - First Option and Second Option of the First Aspect of the Present Invention] As described above, the first and second options of the first aspect of the present invention do not include the step of drying the acid-modified alumina suspension (known as equilibrium sedimentation filtration (hereinafter, "EDF")) before adding the solution of the titanium compound.

[0049] [Comparative Example 1: Equilibrium sedimentation filtration of TALH without addition of acid (hereinafter, referred to as "EDF")] 38.8 g of Puralox SCCa-150 was suspended in 46.5 g of water to obtain an aqueous suspension of 45.5 wt% Al2O3. 164 g of an aqueous TALH solution (1 wt% TiO2) was added to the alumina suspension, heated at 50 °C for 3 hours, filtered, dried, and calcined at 550 °C. The obtained modified carrier contained 1.1 wt% TiO2 (based on the total weight of the modified carrier).

[0050] [Comparative Example 2 - The same process as in Patent Document 2 (WO 2013 / 114098 A1): EDF of TALH in one step with pre-mixed citric acid] 38.6 g of Puralox SCCa-150 was suspended in 46 g of water (45.5 wt% suspension). A mixed solution of 160 g of TALH and citric acid was added to the suspension (1 wt% TiO2 = 11 g of TALH, 20 wt% citric acid with respect to the amount of TALH used = 2.2 g). The mixture was heated, stirred at 50 °C for 3 hours, filtered, dried, and calcined at 550 °C. The obtained modified carrier contained 1.7 wt% TiO2 (based on the total weight of the modified carrier).

[0051] [Example 1: EDF of TALH containing citric acid (AP15-171)] 38.8 g of Puralox SCCa-150 was suspended in 46.5 g of water to obtain an aqueous suspension of 45.5 wt% Al2O3. 11.2 g of a 40 wt% citric acid solution was added to the suspension to adjust the pH of the suspension to 4, producing an acid-modified alumina suspension. Next, 164 g of a 1 wt% TiO2 TALH aqueous solution was added to the acid-modified alumina suspension, and the suspension of alumina / titanium compound was heated at 50 °C for 3 hours under pH control to 4 using citric acid, filtered, dried, and calcined at 550 °C. The resulting catalyst support contained 2.2 wt% TiO2 (based on the total weight of the modified support).

[0052] The examples show that when an acid is added to the alumina suspension before adding the Ti compound, the TiO2 adsorption on the alumina is significantly higher compared to the case without acid treatment or when titania (TiO2) and acid are premixed, as in Comparative Example 1 and Comparative Example 2.

[0053] The Ti:Al ratio of the current particles prepared as in Example 1 and the crushed (broken) samples of the catalyst support was found to be approximately the same. Therefore, the surface distribution of titania is considered to be uniform over the inner and outer surfaces of the support particles. When the alumina support is functionalized with an acid before impregnation with TALH as in Example 1, a uniform Ti distribution is obtained compared to Comparative Example 2, where a non-uniform Ti distribution was obtained by contacting the catalyst support with a titanium compound and a carboxylic acid simultaneously without pre-treating the catalyst support material with an acid (see the Ti:Al peak ratio of XPS in Example 1 of Table 1).

[0054] The results of the support modification demonstrate that the improvement in adsorption is a function of pH and the fact that the surface of alumina is functionalized by an acid.

[0055] The results are included in Table 1 below.

[0056]

Table 1

[0057] [Example - Third and Fourth Options of the First Aspect of the Invention] As described before for Options 3 and 4 of the first aspect of the present invention, a step of drying the acid-modified alumina suspension (known as the solution dropwise impregnation method (hereinafter, "IW")) is included before adding the solution of the titanium compound.

[0058] [Comparative Example 3: IW of TALH without Acid Addition] 13.7 g of TALH was dissolved in water to obtain 21 mL of the synthesized TALH aqueous solution. Then, during strong mixing, the TALH solution was dropped into 54.4 g of the Puralox SCCa-2 / 150 suspension. Water was removed at 80 °C under atmospheric pressure and calcined at 550 °C for 3 hours. The obtained carrier contained 4.1 wt% of TiO2, but the distribution of TiO2 was non-uniform (see Table 2 and Figure 1).

[0059] [Comparative Example 4: One-step IW (pre-mixing) of TALH using 20 wt% citric acid (expressed in relation to TALH)] 11.3 g of TALH was dissolved in water to obtain 18 mL of the synthesized TALH aqueous solution. 2.3 g of citric acid was added as a solid to the TALH solution. Under strong mixing, this solution was added to 38.8 g of the Puralox SCCa-2 / 150 suspension. Water was removed at 80 °C under atmospheric pressure and calcined at 550 °C for 3 hours. In the obtained catalyst carrier, the distribution of TiO2 was non-uniform.

[0060] [Example 2: Two-step process of 20 wt% citric acid, drying, and IW of TALH] 18 mL of a 20 wt% citric acid solution was added to 38.8 g of the Puralox SCCa-2 / 150 suspension and mixed. The mixture was dried at 80 °C under atmospheric pressure. 11.3 g of TALH was dissolved in water to obtain 18 mL of the TALH aqueous solution. This solution was added to the dried mixture of the acid-modified Puralox to form an alumina / titanium compound suspension. Then, this alumina / titania compound suspension was dried at 80 °C to remove water and calcined at 550 °C for 3 hours to obtain a catalyst carrier containing 4.1 wt% of TiO2 with a uniform dispersion of TiO2.

[0061] [Example 3: 5 wt% citric acid, drying, and two steps of IW of TALH] A modified alumina support containing 4.1 wt% of TiO2 was prepared as described in Example 2, but Puralox was treated with a 5 wt% citric acid solution. The uniformity of the dispersion of TiO2 on the modified support was good as shown in Table 2 and Figure 2.

[0062] [Example 4: 10 wt% lactic acid, drying, and two steps of IW of TALH] To 29.2 g of a Puralox SCCa-150 suspension, 14 mL of a 10 wt% lactic acid solution was added and mixed. The mixture was dried at 80 °C under atmospheric pressure. 8.5 g of TALH was dissolved in water to obtain 14 mL of an aqueous TALH solution. This was added to the dried product of the acid-treated Puralox to form a suspension of alumina / titanium compound. Then, the suspension of alumina / titanium compound was dried at 80 °C to remove water and calcined at 550 °C for 3 hours to obtain a support for a catalyst of 4.1 wt% of TiO2 with a uniform dispersion of the Ti compound.

[0063] [Example 5 - 5 wt% lactic acid, drying, and two steps of IW of TALH] To 29.1 g of a Puralox SCCa-150 suspension, 13 mL of a 5 wt% lactic acid solution was added and mixed. The mixture was dried at 80 °C under atmospheric pressure. 8.5 g of TALH was dissolved in water to obtain 13 mL of an aqueous TALH solution. This was added to the dried mixture of the acid-treated Puralox as prepared in the first step to form a suspension of alumina / titanium compound. The suspension of alumina / titanium compound was dried at 80 °C to remove water and calcined at 550 °C for 3 hours. The uniformity of the dispersion of TiO2 on the catalyst support was good.

[0064] As outlined in the examples and Table 2, adding an acid to the alumina suspension before contacting the alumina suspension or mixture with a titanium compound (TALH), through a two-step treatment process, can significantly improve the adsorption of TiO2, indicating that titania is uniformly distributed on the inner and outer surfaces of the alumina support.

[0065]

Table 2

[0066] [Example of the Fourth Aspect of the Present Invention: Example of Mn Impregnation] [Comparative Example 5: IW of TALH without Acid Pretreatment and IW of MnAc] The catalyst support was prepared as described in Comparative Example 3, but after firing, manganese acetate (MnAc) was added by the solution dropping impregnation method.

[0067] 26.9 g of TALH was dissolved in water to obtain 42 mL of the synthesized TALH aqueous solution. This was dropped onto 91.8 g of Puralox SCCa-150 and mixed with a Krups stirrer. Water was removed at 120 °C under atmospheric pressure and fired at 550 °C for 3 hours. 12.5 g of manganese acetate tetrahydrate (Mn(CH3COO)2·4H2O) was dissolved in 42 mL of water and dropped onto the fired powder. The catalyst support was dried at 120 °C and fired again at 550 °C for 3 hours to obtain a catalyst containing 3.9 wt% of TiO2 and 4.7 wt% of MnO2.

[0068] [Comparative Example 6: IW of TALH Using 20 wt% Citric Acid in One Step and IW of MnAc] The catalyst support was prepared as described in Comparative Example 4, but in the second solution dropping impregnation method step after drying, manganese acetate (MnAc) was added.

[0069] 22.8 g of TALH was dissolved in water to obtain 36 mL of the synthesized TALH aqueous solution. 4.6 g of citric acid was added as a solid to the TALH solution. While mixing with a Krups stirrer, this solution was dropped onto 78 g of Puralox SCCa-2 / 150. Water was removed at 120 °C under atmospheric pressure. 10.6 g of manganese acetate tetrahydrate was dissolved in 36 mL of water, dropped onto this dry powder, dried at 120 °C under atmospheric pressure, and fired in air at 550 °C for 3 hours. The modified support was composed of 3.9 wt% of TiO2 and 4.7 wt% of MnO2

[0070] [Comparative Example 7: IW of TALH in one step and IW of MnAc using 20 wt% citric acid] The catalyst support was prepared as described in Comparative Example 4, but MnAc was added during the IW of TALH with citric acid.

[0071] 22.8 g of TALH, 10.6 g of manganese acetate, and 4.6 g of citric acid were dissolved in water to obtain 36 mL of an aqueous solution. While mixing with a Krups stirrer, this solution was added dropwise to 78 g of Puralox SCCa-2 / 150. Water was removed under atmospheric pressure at 120 °C, and the powder was calcined in air at 550 °C for 3 hours. The modified support consisted of 3.9 wt% TiO2 and 4.7 wt% MnO2.

[0072] [Example 6: TALH pretreated with 5 wt% citric acid and two steps of IW of MnAc] The catalyst support was prepared as described in Example 3, but MnAc was added during the solution dropwise impregnation method of TALH with citric acid.

[0073] To 34 mL of 73.9 g of Puralox SCCa-2 / 150, a 5 wt% citric acid solution was added and mixed. The mixture was dried at 80 °C under atmospheric pressure. 21.5 g of TALH and 10 g of manganese(II) acetate tetrahydrate (Mn(CH3COO)2·4H2O) were dissolved in water to obtain 34 mL of a TALH / Mn acetate aqueous solution.

[0074] As prepared in the first step, the dried and acid-treated Puralox was added with the TALH / MnAc aqueous solution by impregnation in the second step, dried at 80 °C to remove moisture, and calcined at 550 °C for 3 hours to obtain a modified support of 4.1 wt% TiO2 and 4.7 wt% MnO2. Drying was carried out at 80 °C to prevent significant acid loss during drying.

[0075] [Example 7: EDF of TALH, 5 wt% citric acid, and two steps of IW of manganese acetate] The catalyst support was prepared as described in Example 1, but MnAc was added by the solution dropwise impregnation method after calcination.

[0076] The Al2O3 in the aqueous suspension was prepared by mixing 85.8 g of Puralox SCCa-2 / 150 with 102 mL of water, and the pH of the suspension was adjusted to 4 with a 40 wt% citric acid solution. Then, 950 g of a 1 wt% TiO2 TALH aqueous solution was added to the suspension, and it was heated at 50 °C for 3 hours under pH control to 4 using citric acid. The suspension was filtered, dried, and calcined at 550 °C. After calcination, 12.4 g of manganese acetate tetrahydrate was dissolved in 43 mL of water, dropped onto the powder, dried at 120 °C, and calcined at 550 °C for 3 hours.

[0077] The results of the XPS peak ratios for Comparative Example 5 and Example 6 are included in Table 3 of the Ti- and Mn-modified samples prepared via the solution dropwise impregnation route, indicating that titania is mainly located on the inner surface of the support, while manganese is uniformly located on both the inner and outer surfaces of the support.

[0078] The results are included in Table 3 below.

[0079]

Table 3

Claims

Claim 1 Alumina carrier (Al ２ O ３ ) with 1 to 5 wt% of TiO ２ is a carrier of a fired catalyst composed of an alumina carrier with its surface coated, The TiO ２ is uniformly dispersed on the alumina carrier, The surface coating includes the coating on the surface of the inner pore wall of the alumina support, and does not include the coating within the bulk of the alumina support. The difference in the peak area ratio determined by X-ray photoelectron spectroscopy of Ti:AL between the support of the calcined catalyst before grinding using a pestle and mortar and the support of the calcined catalyst after grinding using a pestle and mortar is 0.0067 or less. Support of the calcined catalyst. Claim 2 Regarding the peak area ratio determined by X-ray photoelectron spectroscopy of Ti:AL of the support of the calcined catalyst, the difference between the case before grinding using a pestle and mortar and the case after grinding using a pestle and mortar is negative. The support of the calcined catalyst according to Claim 1.

Images