RU2792847C2 - Catalyst substrate containing evenly distributed titanium dioxide and its manufacturing method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to a method for the manufacture of catalyst substrate containing at least evenly distributed titanium dioxide and aluminum oxide, to catalyst substrate manufactured by this method, as well as to a method for the production of activated catalyst substrate. The method for the manufacture of catalyst substrate includes following stages: i) preparation of an aluminum oxide suspension having a pH value from 6 to 8, wherein the aluminum oxide suspension contains aluminum oxide selected from a group consisting of transition aluminum oxide, boehmite, and mixtures thereof; ii) preparation of a titanium compound solution; iii) addition of acid to the aluminum oxide suspension until the pH value of the aluminum oxide suspension is from 4 to 5 to obtain an acid-modified aluminum oxide suspension; iv) addition of the titanium compound solution to the acid-modified aluminum oxide suspension to obtain an aluminum oxide/titanium compound suspension; and v) drying of the aluminum oxide/titanium compound suspension and calcination to obtain catalyst substrate. Calcinated catalyst substrate contains substrate of aluminum oxide, covered with TiO₂ in amount from 1 to 5 wt.% per the weight of substrate of aluminum oxide (Al₂O₃), wherein TiO₂ is evenly distributed along substrate of aluminum oxide, forming surface coating on a surface of substrate of aluminum oxide, including coating of surfaces of walls of inner pores of material of substrate of aluminum oxide, not being in a volume of substrate of aluminum oxide.

EFFECT: provision of even distribution of a titanium compound along catalyst substrate of aluminum oxide.

14 cl, 2 dwg, 3 tbl, 7 ex

Description

FIELD OF TECHNOLOGY

The present invention relates to a method for manufacturing a catalyst support containing at least uniformly (uniformly) distributed titanium dioxide and alumina, and to a catalyst support made by this method.

PRIOR ART

WO 2014/020507 A2 describes a method for incorporating a titanium compound into a catalyst support material by impregnation. A suitable liquid impregnation medium may be used to provide contact between the titanium compound and the catalyst support material. Examples from WO 2014/020507 A2 disclose the use of ethanol as an organic liquid medium for contacting a catalyst support material with a titanium compound during the manufacture of a titanium compound-modified catalyst support. Although not exemplified, WO 2014/020507 A2 also discloses that an inorganic liquid medium such as water can be used to bring the catalyst support material into contact with the titanium compound.

WO 2013/114098 A1 discloses a method in which an aqueous composition containing a carboxylic acid and a titanium compound is prepared and simultaneously added to a catalyst support material, i.e. a mixture of a titanium compound and a carboxylic acid is added to the catalyst support material.

US 2005/0124490 discloses a homogeneous amorphous catalyst support containing a builder metal oxide and an alkali metal oxide, in which the builder metal oxide is uniformly distributed in the alkali metal oxide. US 2005/0124490 describes a precipitation process in which aluminate salts are used as starting materials for producing modified alumina.

Prior art manufacturing methods either differ or result in catalysts in which the titanium compound is not uniformly (ie, not uniformly) distributed over the catalyst support. Therefore, there is a need to improve such methods.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a method for manufacturing a catalyst support, which includes:

i) preparing an alumina slurry having a pH value ranging from 6 to 8, the alumina slurry comprising an alumina selected from the group consisting of transitional alumina, boehmite and mixtures thereof, and preferably being γ-alumina;

ii) preparing a titanium compound solution;

iii) adding acid to the alumina slurry until the pH of the alumina slurry is in the range of 4 to 5 to obtain an acid-modified alumina slurry; And

iv) adding the titanium compound solution to the acid-modified alumina slurry to form an alumina/titanium compound slurry.

The method may include the additional step of adding an acid to the alumina/titanium compound slurry to form an acid-modified alumina/titanium compound slurry.

The method may include the additional step of heating the alumina/titanium compound slurry or the acid-modified alumina/titanium compound slurry to form a heated alumina/titanium compound slurry or a heated acid-modified alumina/titanium compound slurry. Heating is carried out at a temperature ranging from 30°C to 70°C, typically at a temperature of about 50°C, for a period of time ranging from 2 hours to 4 hours.

The method may include the step of drying the heated alumina/titanium compound slurry or the heated acid-modified alumina/titanium compound slurry.

The method may include the step of drying the acid-modified alumina slurry prior to adding the titanium compound solution to form a dried acid-modified alumina mixture.

According to a first embodiment of the first aspect of the present invention, there is provided a method for manufacturing a catalyst support, which includes:

i) preparing an alumina slurry having a pH value ranging from 6 to 8, the alumina slurry comprising an alumina selected from the group consisting of transitional alumina, boehmite and mixtures thereof, and preferably being v-alumina;

ii) preparing a titanium compound solution;

iii) adding acid to the aluminum slurry until the pH of the alumina slurry is in the range of 4 to 5 to obtain an acid-modified alumina slurry;

iv) adding the titanium compound solution to the acid-modified alumina slurry to form an alumina/titanium compound slurry; And

v) drying the alumina/titanium compound slurry to obtain a dried alumina/titanium compound mixture.

According to a second embodiment of the first aspect of the present invention, there is provided a method for manufacturing a catalyst support, which includes:

i) preparing an alumina slurry having a pH value ranging from 6 to 8, the alumina slurry comprising an alumina selected from the group consisting of transitional alumina, boehmite and mixtures thereof, and preferably being γ-alumina;

ii) preparing a titanium compound solution;

iii) adding acid to the aluminum slurry until the pH of the alumina slurry is in the range of 4 to 5 to obtain an acid-modified alumina slurry;

iv) adding the titanium compound solution to the acid-modified alumina slurry to form an alumina/titanium compound slurry;

v) adding an acid to the alumina/titanium slurry to form an acid-modified alumina/titanium slurry; And

vi) drying the acid modified alumina/titanium compound slurry to provide a dried pH modified alumina/titanium compound mixture.

The first embodiment and the second embodiment of the first aspect of the present invention may include an additional step of heating the alumina/titanium compound slurry or the acid-modified alumina/titanium compound slurry. Heating can be carried out at a temperature ranging from 30°C to 70°C, typically at a temperature of about 50°C, and preferably for a period of time ranging from 2 hours to 4 hours.

If the method of the present invention does not include the step of drying the acid-modified alumina slurry before adding the titanium compound solution, then the acid added to the alumina slurry is preferably formic acid, lactic acid, citric acid or mixtures thereof, more preferably it is lactic acid, citric acid or mixtures thereof, and most preferably it is citric acid.

The percentage of acid added to the alumina slurry may range from 5 wt. % up to 30 wt. % by weight of the acid-modified alumina slurry, preferably in the range of 5 wt. % up to 20 wt. % by weight of the acid-modified alumina suspension. However, it should be understood that the amount of acid added should be sufficient to lower the pH of the alumina slurry from pH values ranging from 6 to 8 to pH values ranging from 4 to 5.

According to a third embodiment of the first aspect of the present invention, there is provided a method for manufacturing a catalyst support, which includes:

i) preparing an alumina slurry having a pH value ranging from 6 to 8, the alumina slurry comprising an alumina selected from the group consisting of transitional alumina, boehmite and mixtures thereof, and preferably being γ-alumina;

ii) preparing a titanium compound solution;

iii) adding acid to the aluminum slurry until the pH of the alumina slurry is in the range of 4 to 5 to obtain an acid-modified alumina slurry;

iv) drying the acid-modified alumina slurry to form a dried acid-modified alumina mixture;

v) adding the titanium compound solution to the dried acid-modified alumina mixture to form an alumina/titanium compound slurry; And

vi) drying the alumina/titanium compound slurry to obtain a dried alumina/titanium compound mixture.

According to a fourth embodiment of the first aspect of the present invention, there is provided a method for manufacturing a catalyst support, which includes:

i) preparing an alumina slurry having a pH value ranging from 6 to 8, the alumina slurry comprising an alumina selected from the group consisting of transitional alumina, boehmite and mixtures thereof, and preferably being γ-alumina;

ii) preparing a titanium compound solution;

iii) adding acid to the alumina slurry until the pH of the alumina slurry is in the range of 4 to 5 to obtain an acid-modified alumina slurry;

iv) drying the acid-modified alumina slurry to form a dried acid-modified alumina mixture;

v) adding the titanium compound solution to the dried acid-modified alumina slurry to form an alumina/titanium compound slurry;

vi) adding an acid to the alumina/titanium compound slurry to form an acid-modified alumina/titanium compound slurry; And

vii) drying the acid modified alumina/titanium compound slurry to form a dried acid modified alumina/titanium compound mixture.

The third embodiment and the fourth embodiment of the first aspect of the present invention may include an additional step of heating the alumina/titanium compound slurry or the acid-modified alumina/titanium compound slurry. Heating can be carried out at a temperature ranging from 30°C to 70°C, typically at a temperature of about 50°C, and preferably for a period of time ranging from 2 hours to 4 hours.

It should be understood that the amount of acid added in step vi) of the fourth embodiment of the first aspect of the present invention is sufficient to maintain the pH of the alumina/titanium compound slurry in the range of 4 to 5.

If the method of the present invention involves drying the acid-modified alumina slurry prior to adding the titanium compound solution, then the added acid is preferably a carboxylic acid (an organic compound that contains at least one carboxyl group (C(=O)OH)) including formic acid , lactic acid, citric acid, or mixtures thereof.

The percentage of acid added to the alumina slurry is in the range of 5 wt. % up to 30 wt. % by weight of the acid-modified alumina slurry, preferably in the range of 5 wt. % up to 20 wt. % by weight of the acid-modified alumina suspension. However, it should be understood that the amount of acid added should be sufficient to lower the pH of the alumina slurry from pH values ranging from 6 to 8 to pH values ranging from 4 to 5.

It is preferable not to dry the acid-modified alumina slurry before adding the titanium compound solution, such as in the first and second embodiments of the first aspect of the present invention (known as equilibrium deposition filtration (EDF)), or to dry the modified alumina slurry. alumina acid before adding the titanium compound solution as in the third and fourth embodiments of the first aspect of the present invention (known as IW impregnation).

The method (and embodiments thereof) according to the first aspect of the present invention may include the final step of calcining (calcining) the dried alumina/titanium compound mixture or the dried acid-modified alumina/titanium compound mixture. Calcination is carried out at temperatures typically ranging from 100°C to 1000°C, preferably in the range from 400°C to 600°C, in all cases preferably for a period of time ranging from 2 hours to 5 hours to obtain a calcined (heat-treated) catalyst support.

The transition alumina is preferably γ-alumina (gamma), 5-alumina (delta), θ-alumina (theta), or mixtures thereof. Most preferably, the transition alumina is γ-alumina.

The alumina slurry is preferably prepared by suspending an alumina selected from the group consisting of transition alumina, boehmite and mixtures thereof, and preferably being γ-alumina, in at least water. The percentage of alumina in the slurry is in the range of 5% to 60% of the total alumina slurry, preferably in the range of 40% to 50% of the total alumina slurry.

The alumina in the alumina slurry is preferably exclusively an alumina selected from the group consisting of transition alumina, boehmite and mixtures thereof, and is preferably exclusively γ-alumina.

The titanium compound solution is obtained by dissolving the titanium precursor (precursor) in at least water. Water-soluble titanium precursors containing potassium titanium oxalates, ammonium titanium oxalates, ammonium titanium lactates or mixtures thereof can be used. If necessary, the temperature of at least water can be raised to 90°C to speed up the dissolution process. The concentration of the titanium precursor in solution should be as high as possible and be determined solely by the solubility of the titanium precursor in at least water. The preferred titanium solution is an aqueous solution of dehydrated potassium titanium oxalate with a concentration ranging from 1 wt. % up to 4 wt. % in terms of TiO ₂ . The titanium solution can be stirred with a magnetic stirrer for about 30 minutes before being added to the alumina slurry. The titanium solution is preferably passed through an ion exchange column to remove any contaminants, such as potassium, before being added to the alumina slurry. Therefore, the titanium solution is preferably stirred with a magnetic stirrer for a certain period of time and (and also independently) passed through an ion exchange column before adding to the suspension of alumina.

Any drying methods known in the art can be used in the method of the present invention. Drying is typically performed for a period of time ranging from 0.5 hours to 5 hours at a temperature ranging from 80°C to 120°C.

Suspension of alumina/titanium compounds contains from 99 wt. % up to 95 wt. % alumina, most preferably from 97 wt. % to 99 wt. %, in terms of Al ₂ O ₃ , and preferably from 1 wt. % up to 5 wt. %, most preferably from 1 wt. % up to 3 wt. %, titanium compounds in terms of TiO ₂ , from the sum of the masses of aluminum oxide in terms of Al ₂ O ₃ and titanium compounds in terms of TiO ₂ .

The dried mixture of alumina (including modified acid/pH)/titanium compounds preferably contains from 99 wt. % up to 95 wt. %, most preferably from 99 wt. % to 97 wt. %, aluminum oxide in terms of Al ₂ O ₃ , and preferably from 1 wt. % up to 5 wt. %, most preferably from 1 wt. % up to 3 wt. %, titanium compounds in terms of TiO ₂ , based on the total weight of the dried mixture of alumina (including modified acid/pH)/titanium compounds.

According to a second aspect of the present invention, there is provided a catalyst support made according to the first aspect of the present invention.

According to a third aspect of the present invention, there is provided a calcined catalyst support comprising an alumina support coated with TiO ₂ in an amount ranging from 1 wt. % up to 5 wt. % by weight of the alumina substrate (Al ₂ O ₃ ), with TiO ₂ evenly distributed over the alumina substrate.

When used in the context of the present invention, the terms "coated/coated" means a surface coating formed on the surface of the substrate material, including coating surfaces of the walls of the internal pores of the substrate material (but not in the volume of the substrate).

The catalyst support preferably comprises an alumina support coated with TiO ₂ in an amount ranging from 3 wt. % up to 5 wt. % (as measured after calcination) based on the weight of the alumina (Al ₂ O ₃ ) substrate.

The weight % TiO ₂ in the catalyst support made according to the first aspect of the present invention is expressed in terms of the total weight of the catalyst support.

Most surprisingly, if the alumina slurry is first treated with an acid (or acids), i.e. before the alumina slurry contacts the titanium compound solution, a more uniform distribution of the titanium compound over the alumina catalyst support is provided.

According to a fourth aspect of the present invention, there is provided a method for manufacturing an activated catalyst support, which includes:

i) fabricating a catalyst support according to the first aspect of the present invention; And

ii) applying an activator to the surface of the catalyst support and/or incorporating it into the catalyst support to form an activated catalyst support.

The activator is preferably a manganese compound, including, for example, manganese hydroxides, manganese oxides and/or manganese oxyhydroxides. Manganese can be added to the catalyst support together with the titanium compound solution, ie by mixing a manganese precursor, eg manganese acetate, with the titanium compound solution from step ii) of the first aspect of the present invention. Alternatively, the calcined catalyst support can be impregnated with a manganese precursor such as α-manganese acetate.

The fourth aspect of the present invention may include a final calcination (calcination) step.

The catalyst support or activated catalyst support made according to the present invention can be used for Fischer-Tropsch reaction catalysts, hydrocarbon synthesis catalysts, hydrodesulfurization catalysts, hydroprocessing catalysts, and NO oxidation photocatalysts, among others.

BRIEF DESCRIPTION OF GRAPHICS

Hereinafter the invention will be described in more detail with reference to the accompanying drawings and the following non-limiting examples, where:

Fig. 1 is a scanning electron microscopy (SEM) image of a cross section of the substrate of Comparative Example 3, in which white spots reflect TiO ₂ enrichment; And

Fig. 2 is a cross-sectional SEM image of the substrate from Example 3.

DESCRIPTION OF EXAMPLES OF CARRYING OUT THE INVENTION

Description of experiments

Bis(ammonium lactato)dihydroxide titanium (IV) (TALH, from the English. titanium(IV) bis(ammonium lactato) dihydroxide) was used in the form of 1 wt. % aqueous solution of TALH (in terms of TiO ₂ ), known under the trade name Tyzor® LA.

In the examples below, wt. % Ti in terms of TiO ₂ in the catalyst support is expressed in terms of the total weight of the catalyst support.

X-ray photoelectron spectroscopy (XPS; from English: X-ray photoelectron spectroscopy) was used in the examples below to determine the distribution of TiO ₂ on the surface of the alumina. XPS is a quantitative spectroscopic surface evaluation technique that measures the elemental composition in fractions per thousand. Since XPS only provides surface analysis, the samples were analyzed by XPS immediately after manufacture (particles as such) and after grinding (crushing) using a pestle and mortar, and element ratios were recorded. For the grinding step using the pestle and mortar, about the same amount of sample was used (compared to the samples in which the particles were measured as such) and a force was applied sufficient to break the particles.

XPS spectra were recorded on a KRATOS Axis Ultra DLD instrument, with the analyzer operating at a fixed run energy of 160 eV in the case of a survey spectrum and 20 eV for individual regions. The measurements were carried out using a monochromatic source with the line Al K _α . Due to the nature of the materials, neutralization was necessary during registration. All spectra were energy corrected using the C 1s line at 284.6 eV. All loose powder samples were fixed in a molybdenum sample holder. The ratios of the peak areas obtained by XPS for all of the substrate samples indicated in the Examples are shown in Tables 1, 2 and 3 together with the calculated difference between the particles as such and the crushed sample. The larger this difference, the less homogeneous the sample is. Homogeneous samples give very small or even negative values.

EXAMPLES Embodiments 1 and 2 of the First Aspect of the Present Invention

As described above, embodiments 1 and 2 of the first aspect of the present invention do not include the step of drying the acid-modified alumina slurry before adding the titanium compound solution (such a method is known as equilibrium precipitating filtration (hereinafter "EDF").

Comparative Example 1

Equilibrium precipitating filtration TALH (hereinafter "EDF") without the addition of acid

38.8 g Puralox SCCa-150 was suspended in 46.5 g water to give 45.5 wt. % Al ₂ O ₃ in aqueous suspension. To the suspension of alumina was added 164 g of an aqueous solution of TALH (1 wt.% TiO ₂ ) and heated for 3 hours at 50°C, then filtered, dried and calcined at 550°C. The resulting modified substrate contained 1.1 wt. % TiO ₂ (in terms of the total weight of the modified substrate).

Comparative Example 2

Same process as described in WO 2013/114098 A1: one step: EPF TALH with citric acid - premix

38.6 g of Puralox SCCa-150 were suspended in 46 g of water (to obtain a suspension containing 45.5 wt.% Al ₂ O ₃ ). To the suspension was added 160 g of a mixed solution of TALH and citric acid (1 wt. % TiO ₂ =11 g TALH, 20 wt. % citric acid based on 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 resulting modified substrate contained 1.7 wt. % TiO ₂ (in terms of the total weight of the modified substrate).

Example 1

EPF TALH with citric acid (AP15-171)

38.8 g Puralox SCCa-150 was suspended in 46.5 g water to give 45.5 wt. % Al ₂ O ₃ in aqueous suspension. 11.2 g of a solution of citric acid with a concentration equal to 40 wt. % was added to the slurry to adjust the pH of the slurry to a pH value of 4 to obtain an acid-modified alumina slurry. Then, 164 g of an aqueous solution of TALH containing 1 wt. % TiO ₂ , and a mixture of alumina/titanium compounds was heated for 3 hours at 50°C, adjusting the pH using citric acid, filtered, dried and calcined at 550°C. The resulting modified substrate contained 2.2 wt. % TiO ₂ (in terms of the total weight of the modified substrate).

These examples demonstrate that the addition of acid to the alumina slurry prior to the addition of the Ti compound results in significantly higher adsorption of TiO ₂ to the alumina compared to no acid treatment or premixing the acid with titanium oxide (TiO ₂ ) as in Comparative Examples 1 and 2.

It was found that the ratios of Ti:Al in the particle as such and in the crushed (crushed) catalyst support sample prepared in Example 1 were approximately the same, and therefore the surface distribution of titanium oxide was found to be uniform over the entire inner and outer surface of the support particle. Functionalization of the alumina support with an acid, in this case citric acid, prior to EDF impregnation with TALH, as in Example 1, resulted in a uniform distribution of Ti (see Table 1, Example 1, Ti:Al peak area ratios) compared to Comparative Example 2, in which the titanium compound and the carboxylic acid were contacted with the catalyst support at the same time without pre-treatment of the catalyst support material with acid, in which the uneven distribution of Ti was obtained.

The results of the substrate modification demonstrate that the increase in adsorption is a function of pH, as well as the fact that the surface of the alumina is acid-functionalized.

The results are presented in Table 1 below.

EXAMPLES Embodiments 3 and 4 of the First Aspect of the Present Invention

As described above, embodiments 3 and 4 of the first aspect of the present invention include the step of drying the acid-modified alumina slurry before adding the titanium compound solution (such a method is known as wetness impregnation; hereinafter IW).

Comparative Example 3: IW TALH without added acid

13.7 g of TALH was dissolved in water, resulting in 21 ml of an aqueous solution of TALH. The TALH solution was then added dropwise to 54.4 g of the Puralox SCCa-2/150 suspension while stirring vigorously. The water was removed at atmospheric pressure at 80°C and calcined at 550°C for 3 hours. The resulting catalyst substrate contained 4.1 wt. % TiO ₂ but the distribution of TiO ₂ was uneven (see Table 2 and Fig. 1).

Comparative Example 4

1-stage - IW TALH with 20 wt. % citric acid (calculated as TALH) (premix)

11.3 g of TALH was dissolved in water, resulting in 18 ml of an aqueous solution of TALH. To the TALH solution was added 2.3 g of citric acid in the form of a solid. This solution was added to 38.8 g of Puralox SCCa-2/150 suspension with vigorous stirring. The water was removed at atmospheric pressure at 80°C and calcined at 550°C for 3 hours. The resulting catalyst support had an uneven distribution of TiO ₂ .

Example 2

2 stages: 20 wt. % citric acid, drying, IWTALH

18 ml of a 20 wt% solution of citric acid was added to 38.8 g of a suspension of Puralox SCCa-2/150 and the mixture was allowed to mix. The mixture was dried at 80° C. under atmospheric pressure. 11.3 g of TALH was dissolved in water to obtain 18 ml of an aqueous solution of TALH. This solution was added to the dried Puralox acid-modified mixture to give an alumina/titanium compound slurry. This alumina/titania slurry was then dried at 80° C. to remove water and calcined at 550° C. for 3 hours to obtain a catalyst support containing 4.1 wt. % TiO ₂ , with a uniform distribution of TiO ₂ .

Example 3

2 stages: 5 wt. % citric acid, drying, IWTALH

A modified alumina substrate with 4.1 wt. % TiO ₂ was prepared as described in Example 2, however Puralox was treated with 5 wt% citric acid solution. The distribution uniformity of TiO ₂ on the modified substrate was good according to Table 2 and FIG. 2.

Example 4

2 stages: 10 wt. % lactic acid, drying, IWTALH

To 29.2 g of Puralox SCCa-150 suspension was added 14 ml of 10 wt. % lactic acid solution and the mixture was allowed to mix. 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 solution of TALH. This solution was added to the dried mixture of acid-treated Puralox to give the alumina/titanium compound slurry. Then, the suspension of alumina/titanium compounds was dried at 80°C to remove water and calcined at 550°C for 3 hours to obtain a catalyst substrate containing 4.1 wt. % TiO ₂ , with a uniform distribution of the Ti compound.

Example 5

2 stages: 5 wt. % lactic acid, drying, IWTALH

To 29.1 g of Puralox SCCa-150 suspension was added 13 ml of 5 wt. % lactic acid solution and the mixture was allowed to mix. 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 solution of TALH. This solution was added to the dried mixture of acid-treated Puralox obtained during the 1st step to obtain a slurry of alumina/titanium compound. The alumina/titanium slurry was dried at 80° C. to remove water and calcined at 550° C. for 3 hours. The distribution uniformity of TiO ₂ on the catalyst support was good.

According to the examples and results shown in Table 1, adding acid to the alumina slurry before contacting the alumina slurry or mixture with a titanium compound (TALH), i.e. using a 2-step treatment process, showed that TiO ₂ adsorption can be significantly improved. , and titanium dioxide is uniformly distributed over the inner and outer surfaces of the alumina substrate.

Examples for the fourth aspect of the present invention

Examples with Mn impregnation

Comparative Example 5

IW TALH without acid pretreatment, IW MnAc

The catalyst support was prepared as described in Comparative Example 3, but after calcination, manganese acetate (MnAc) was added by wetness impregnation.

26.9 g of TALH was dissolved in water, resulting in 42 ml of an aqueous solution of TALH. This solution was added dropwise to 91.8 g of Puralox SCCa-150 and the mixture was stirred using a Krups stirrer. The water was removed at atmospheric pressure at 120°C and calcined at 550°C for 3 hours. 12.5 g of manganese acetate tetrahydrate (Mn(CH ₃ COO) ₂ ⋅4H ₂ O) was dissolved in 42 ml of water and added dropwise to the calcined powder. The catalyst support was dried at 120°C and again calcined for 3 hours at 550°C to obtain a catalyst containing 3.9 wt. % TiO ₂ and 4.7 wt. % _MnO2 .

Comparative Example 6

Stage 1: IW TALH with 20 wt. % citric acid, IW MnAc

The catalyst support was made as described in Comparative Example 4, but with the addition of manganese acetate (MnAc) during the second stage of moisture capacity impregnation after drying.

22.8 g of TALH was dissolved in water, resulting in 36 ml of an aqueous solution of TALH. 4.6 g of citric acid was added to the TALH solution in the form of a solid. This solution was added dropwise to 78 g of Puralox SCCa-2/150 with stirring using a mixer manufactured by Krups. The water was removed under atmospheric pressure at 120°C. 10.6 g of manganese acetate tetrahydrate was dissolved in 36 ml of water and added dropwise to this dried powder, dried at 120° C. at atmospheric pressure, and calcined for 3 hours at 550° C. in air. The modified substrate contained 3.9 wt. % TiO ₂ and 4.7 wt. % _MnO2 .

Comparative Example 7

1st stage: IWTALH, IW MnAc with 20 wt. % citric acid

The catalyst support was prepared as described in Comparative Example 4, but with the addition of manganese acetate (MnAc) during the wetness impregnation step with TALH-citric acid.

22.8 g of TALH, 10.6 g of manganese acetate tetrahydrate and 4.6 g of citric acid were dissolved in water to give 36 ml of an aqueous solution. This solution was added dropwise to 78 g of Puralox SCCa-2/150 with stirring using a mixer manufactured by Krups. The water was removed at atmospheric pressure at 120°C and the powder was calcined for 3 hours at 550°C in air. The modified substrate contained 3.9 wt. % TiO ₂ and 4.7 wt. % _MnO2 .

Example 6

2 steps: IW TALH and MnAc pre-treated with 5 wt% citric acid

The catalyst support was prepared as described in Comparative Example 3, but with the addition of MnAc during the moisture capacity impregnation step with TALH-citric acid.

To 73.9 g of Puralox SCCa-2/150 was added 34 ml of a solution of citric acid with a concentration equal to 5 wt. % and let them mix. The mixture was dried at 80° C. under atmospheric pressure. 21.5 g of TALH and 10 g of manganese(I) acetate tetrahydrate (Mn(CH ₃ COO) ₂ ⋅4H ₂ O) were dissolved in water to give 34 ml of a TALH/Mn acetate solution. To the dried acid-treated Puralox, which was obtained during the 1st stage, was added an aqueous solution of TALH/MnAc during the 2nd stage of impregnation, dried at 80°C to remove water, and calcined at 550°C for 3 hours to obtain a modified substrate containing 4.1 wt. % TiO ₂ and 4.7 wt. % _MnO2 . Drying was performed at 80°C to prevent large losses of acid during drying.

Example 7

2 steps: EPF TALH and 5 wt% citric acid and IW Mn acetate

The catalyst support was made as described in Example 1, but with the addition of MnAc by impregnation according to moisture capacity after calcination.

A suspension of Al ₂ O ₃ in water was prepared by mixing 85.8 g of Puralox SCCa-2/150 with 102 ml of water, the pH of the suspension was adjusted to pH 4 with a solution of citric acid at a concentration of 40 wt. %. Then to the suspension was added 950 g containing 1 wt. % TiO ₂ aqueous solution of TALH and heated at 50°C for 4 hours while maintaining a pH value of 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 and added dropwise to the powder, dried at 120°C and calcined for 3 hours at 550°C.

The XPS peak ratio results for Comparative Example 5 and Example 6 included in Table 3 for the modified Ti and Mn sample obtained by impregnation by moisture capacity show that titanium dioxide is predominantly localized on the inner surfaces of the substrates, while manganese is evenly distributed on the inner and outer surfaces of the substrates.

The results are shown in Table 3 below.

Claims (21)

1. A method for manufacturing a catalyst support, which includes the following steps: i) preparing an alumina slurry having a pH of 6 to 8, the alumina slurry comprising an alumina selected from the group consisting of transitional alumina, boehmite and mixtures thereof; ii) preparing a titanium compound solution; iii) adding acid to the alumina slurry until the pH of the alumina slurry is between 4 and 5 to obtain an acid-modified alumina slurry; iv) adding the titanium compound solution to the acid-modified alumina slurry to form an alumina/titanium compound slurry; And v) drying the alumina/titanium compound slurry and calcining to form a catalyst support. 2. Method according to claim 1, characterized in that it comprises the additional step of adding acid to the alumina/titanium compound slurry. 3. Method according to claim 1 or 2, characterized in that it comprises the additional step of heating the alumina/titanium compound slurry. 4. The method according to claim 1, characterized in that it includes the additional step of drying the acid-modified alumina slurry before adding the solution of the titanium compound. 5. The method according to any one of paragraphs. 1-3, characterized in that the acid added to the suspension of alumina is formic acid, lactic acid, citric acid or mixtures thereof, preferably it is lactic acid, citric acid or mixtures thereof, and most preferably it is citric acid. 6. The method according to any one of paragraphs. 1-5, characterized in that the suspension of alumina/titanium compounds contains from 99 to 95 wt.% alumina, most preferably from 99 to 97 wt.%, in terms of Al ₂ O ₃ , and preferably from 1 to 5 wt.%, most preferably from 1 to 3 wt.% titanium compounds, calculated as TiO ₂ , based on the sum of the masses of alumina, calculated as Al ₂ O ₃ and titanium compounds, calculated as TiO ₂ . 7. The method according to claim 4, characterized in that the added acid is a carboxylic acid selected from the group consisting of formic acid, lactic acid, citric acid, or mixtures thereof. 8. The method according to claim 1 or 7, characterized in that the percentage of acid added to the suspension of alumina is in the range from 5 to 30 wt.% of the weight of the suspension of acid-modified alumina, preferably it is in the range from 5 to 20% by weight of acid-modified alumina slurry. 9. The method according to any one of paragraphs. 1-8, characterized in that the transition alumina is γ-alumina, δ-alumina, θ-alumina or mixtures thereof, and preferably the transition alumina is γ-alumina. 10. The method according to any one of paragraphs. 1-9, characterized in that the titanium compound solution is obtained by dissolving the titanium precursor in at least water. 11. The method of claim 10, wherein the titanium precursor is a water-soluble titanium precursor selected from the group consisting of potassium titanium oxalates, ammonium titanium oxalates, ammonium titanium lactates, and mixtures thereof. 12. The substrate of the catalyst, made according to any one of paragraphs. 1-11. 13. A calcined catalyst support comprising an alumina support coated with TiO ₂ in an amount of 1 to 5 wt % based on the weight of the alumina support (Al ₂ O ₃ ), the TiO ₂ being evenly distributed over the alumina support, forming a surface coating on the surface of the alumina substrate, including coating the surfaces of the walls of the internal pores of the material of the alumina substrate, but not located in the volume of the alumina substrate. 14. A method for manufacturing an activated catalyst support, which includes: i) the manufacture of a catalyst support according to any one of paragraphs. 1-11, and ii) applying an activator to the surface of the catalyst support and/or incorporating it into the catalyst support to form an activated catalyst support.

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