KR102381005B1 - Method for reducing the sulfur content of anatase titania and the product thus obtained - Google Patents

Abstract

The present invention relates to the field of heterogeneous catalysts. More particularly, the present invention relates to a method for reducing the sulfur content of stabilized titania, the material thus obtained and the use of the material for preparing a carrier material of a heterogeneous catalyst.

Description

Method for reducing the sulfur content of anatase titania and the product thus obtained

The present invention relates to the field of heterogeneous catalysts. More particularly, the present invention relates to a method for reducing the sulfur content of stabilized titania, the material thus obtained and the use of the material for preparing a carrier material of a heterogeneous catalyst.

Titanium dioxide is a well-known material for the preparation of heterogeneous catalysts. Titanium dioxide has a wide range of applications as a catalytic material (eg Klaus catalyst) or catalytic support (eg selective catalytic reduction (SCR) or Fisher-Tropsch) of nitrogen oxides. .

The dominant and in most cases the preferred polymorph for heterogeneous catalysts is the anatase crystal phase. Production of anatase-type TiO ₂ on a large industrial scale depends on the so-called sulfur process, in which titanium-rich raw materials (ilmenite or Ti-slag) are first reacted with concentrated sulfuric acid to form TiOSO. to form ₄ Upon hydrolysis, fine particulate anatase type TiO ₂ having a high water content is obtained (so-called metatitanic acid having the general formula TiO(OH) ₂ ). After subsequent purification steps including reduction and washing processes, pure anatase TiO ₂ can be obtained.

Another procedure for preparing anatase type TiO ₂ is flame hydrolysis of TiCl ₄ , whereby only a mixture of rutile and anatase is obtained.

The performance of a heterogeneous catalyst often depends on its purity. Stray ions can affect the overall conversion and/or selectivity of the catalytic process. Commonly unwanted impurities are phosphorus, sulfur, heavy metals, alkali and alkaline earth metals.

For example, since sulfur reacts with cobalt, a catalytically active component, to form cobalt sulfate (Co _x S _y ), and the formed cobalt sulfate causes a sharply reduced catalytic performance, synthesis gas (syngas, CO and H ₂ ) Fischer-Tropsch synthesis of hydrocarbons from a mixture of ) is very sensitive to sulfur impurities. A typical sulfur concentration of the FT-catalyst is less than 150 ppm, preferably less than 100 ppm. The major impurity in the anatase TiO ₂ produced in the sulfuric acid process is sulfur produced from the adherent sulfuric acid during the manufacturing process. Other stray ionic impurities are in the single- or low-two-digit ppm range and are usually uncritical.

The performance of a heterogeneous catalyst also depends on its physical properties. A very uniform dispersion of the catalytically active material on the carrier is often a prerequisite for observing high conversion. In order to ensure maximum dispersion of the catalytically active centers, the usually large specific surface area of the carrier is important.

In summary, large-scale industrial use of anatase type TiO ₂ for catalytic applications, exhibiting both i) large specific surface area (BET > 40 m 2 /g) and ii) low sulfur concentration (< 150 ppm S) There is a demand for what is.

From a manufacturing point of view, the only industrially large-scale possible of anatase type TiO2, a cost-effective manufacturing process is the sulfuric acid process. The main problem with this process is the high content of sulfur in the final product, which is known to be detrimental for many catalytic applications. Therefore, a process capable of producing anatase-type TiO ₂ on a large industrial scale, with a high specific surface area (> 40 m 2 /g) and a low sulfur content (< 150 ppm S), should be discovered.

Various techniques have been developed to reduce the concentration of sulfur in anatase-type TiO ₂ . The most commonly used technique is washing with water. Typically, sulfuric acid containing anatase TiO ₂ is suspended in water and washed on a filter medium (eg, filter press). The washing process is carried out using cold deionized water or preferably hot deionized water. The minimum concentration of sulfur obtainable by this process is in the range of 0.1 - 0.5% by weight.

By reacting the excess sulfuric acid with a suitable base (NaOH, aqueous ammonia solution, etc.) and removing the salt formed by an excessive washing process using demineralized water, the concentration of sulfur can be significantly lowered to the level of 0.03-0.2 wt%. Especially when basic solutions of metals (eg NaOH or KOH) are used, there is a certain risk of contamination if an excess of base is used to achieve minimal sulfuric acid levels, since the metal ions are not removed from the anatase by washing either. exist.

A step of lowering the sulfur concentration by successive washing cycles by treatment with an excess of strong acid and subsequent removal of metal ions by a washing process with acid can also be carried out. In this case, it is preferable to use an acid (eg acetic acid) which can be easily removed in a washing step or a subsequent potential heating step.

During the production of pigmentary grade titanium dioxide, sulfur is removed by thermal decomposition of sulfuric acid. At temperatures above 500° C., a significant decrease in sulfuric acid contamination is observed, but two processes also occur in the course of this heat treatment. i) TiO2 particles undergo grain growth, and their specific surface area is greatly and irreversibly reduced, and ii) at this temperature, a phase transformation from anatase polymorph to rutile polymorph occurs. These two processes are usually preferred to obtain pigment TiO ₂ with low BET (< 20 m 2 /g) and rutile type TiO ₂ , but from sulfuric acid production process with anatase TiO ₂ having a large surface area and low sulfur content In this regard, the use of such procedures is prohibited.

As a result, there is no process that makes it possible to produce anatase type TiO ₂ exhibiting the following properties by large-scale industrial production. 1. ultra low sulfur content (<150 ppm), 2. BET surface area greater than 20 m/g, preferably greater than 30 m/g, more preferably greater than 40 m/g, 3. pure TiO ₂ in the anatase phase.

There is a need for an anatase-type catalyst carrier material with a low sulfur content that is easily accessible through large-scale industrial production and has a high specific surface area.

In this regard, surprisingly, anatase type titanium dioxide doped with appropriate amounts of silica and/or zirconium oxide and/or aluminum oxide, while maintaining a substantially large specific surface area, is treated at a temperature high enough to decompose the sulfuric acid. It was discovered that it could be In this context, the term “thermal stabilization” refers to anatase type TiO in such a way that i) the rutilization temperature is shifted to a higher temperature, and ii) the tendency towards BET loss is reduced. It should be understood that ₂ is stabilized.

In a typical experiment according to the present invention, anatase type TiO2 having a content of 8% by weight of SiO ₂ by weight is heated for 1 hour at a temperature as high as 1000° C. for 1 hour. The resulting powder exhibits a BET surface area of about 50-70 m 2 /g and residual sulfur contamination of less than 50 ppm. The degree of resistance of anatase to thermal aging is highly dependent on the amount of silica added. Higher amounts of silica have a strong effect on the aging properties, while smaller amounts produce only minor tolerance.

In addition to these effects, silica can also affect the catalytic properties of the final catalyst. Silica can change the overall performance by changing the selectivity and/or conversion rate of the catalyst. Depending on the specific application and the specific requirements relating to the BET surface area, the SiO2, residual S content, the correct materials and calcination conditions have to be adjusted individually for each intended use. Overall, the high calcination temperature reduces both the residual S concentration and the specific surface area.

Basically, any element capable of stabilizing the anatase polymorph may be used in the context of the present invention. Si, Al, Zr among many other common elements for catalytic applications [J Mater Sci (2011) 46: 855-874].

The incorporation of these stable ring elements can be accomplished by a variety of different synthetic approaches. With regard to the substances of the present invention, the following other methods are suitable. 1. Precipitation of SiO ₂ on TiO ₂ . 2. Co-precipitation or co-hydrolysis of TiO2 and SiO2. 3. Mixing of TiO ₂ sol and SiO ₂ sol. 4. Treatment of TiO ₂ with SiO ₂ sol. 5. Treatment of TiO ₂ with a SiO ₂ precursor followed by hydrolysis and/or oxidation to form SiO ₂ . 6. TiO ₂ and SiO ₂ mixing.

Accordingly, the present invention provides that the content of at least one compound selected from oxides of Si, Al and Zr is 2-50% by weight, preferably 2-30% by weight, in terms of oxide, based on the total weight of the oxide, , anatase titanium dioxide having a sulfur content of less than 150 ppm, preferably less than 100 ppm, more preferably less than 80 ppm, relative to the total weight of the oxide.

The anatase material of the present invention preferably has a content of alkali such as Na ⁺ less than 200 ppm, preferably less than 100 ppm, so as to avoid the negative influence of alkali on the stability of the material in the course of use.

According to the invention, anatase titanium dioxide is preferably obtained by a sulfuric acid process, which is obtained as hydrated forms thereof comprising titanium dioxide and metatitanic acid. The hydrate forms of metatitanic acid and titania, which are used simultaneously in the present specification, can be expressed by the formula TiO _(2-x) (OH) _2x (0 ≤ x ≤ 1), and also includes titania. The metatitanic acid is then further treated to incorporate a stabilizing agent selected from Si, Zr and/or Al in the form of oxides or hydrates thereof, and then sulfur-containing compounds such as sulfuric acid as a residue of the sulfuric acid process. It is calcined so that it can be decomposed. In the course of the calcination treatment, the hydrate form is converted to an oxide, and the content of the hydrate is reduced to zero, which is clear to a person skilled in the art.

The term "anatase titanium dioxide or anatase titania" as used according to the invention means that at least 95% by weight, preferably 98% by weight and most preferably 100% of titania is present in the form of anatase. Generally, the anatase phase has a crystallite size of 5-50 nm. Thus, with respect to the material of the present invention, after drying at 105° C. for at least 120 minutes prior to calcination, and also after calcination due to stabilization, the crystalline phases of the particles are mostly present in the anatase phase. That is, after subtracting the linear base, the height of the largest peak of the anatase structure (reflex (101)) to the height of the strongest peak of the rutile structure (reflex (100)) is at least 5:1, Preferably at least 10:1. Most preferably, XRD analysis shows only anatase peaks. With regard to measuring phase and crystallite size by Scherrer, in particular crystal deformation (phase identification), X-rays are taken. In this regard, the intensity of the Bragg condition after diffraction in the lattice plane of crystal X-rays is measured for a diffraction angle 2 theta. X-ray diffraction is a characteristic of this phase.

Drying as used in connection with the present invention is drying at a temperature exceeding 105° C. at atmospheric pressure. All large-scale industrial techniques such as spin-flash or spray drying can be applied, but drying is not limited to the techniques mentioned.

The calcination step used according to the invention, while maintaining the content of titania in anatase form, decomposes residual sulfur-containing compounds, such as sulfuric acid, to less than 150 ppm, preferably less than 100 ppm, more preferably less than 100 ppm, based on the total weight of the oxide. Preferably for a time sufficient to reduce the sulfur content to a concentration of less than 80 ppm, preferably for a time between 30 minutes and 1200 minutes, at an elevated temperature above 500° C., preferably at a temperature of 800° C. to 1200° C. It means treating the stabilized anatase titania in The calcination step can be carried out in a conventional calcination device under atmospheric pressure so that sulfur-containing components can evaporate from the material.

As used herein, a weight ratio, ppm-value or percentage refers to the weight of a material after calcination.

Due to the high temperature treatment, detrimental agglomeration may occur for subsequent processing to form the catalyst. Accordingly, deagglomeration of the calcined material by a milling process may be required. Both wet and dry milling techniques can be applied, and common techniques are ball milling or jet milling. An optional sieving step may be followed to ensure that coarse particles have been removed.

Then, the obtained anatase TiO ₂ can function as a catalyst support material, which includes Co, Ni, Fe, W, V, Cr, Mo, Ce, Ag, Au, Pt, Pd, Ru, Further treatment with at least one catalytically active metal selected from Rh, Cu, or mixtures thereof yields a metal loaded catalyst carrier material. of a catalytically active metal selected from Co, Ni, Fe, W, V, Cr, Mo, Ce, Ag, Au, Pt, Pd, Ru, Rh, Cu, or mixtures thereof, dissolved in a polar or non-polar solvent Precursor compounds may be used. Treatment of the carrier material with one precursor compound of a catalytically active metal or a mixture thereof can be effected by a variety of techniques. Common methods include incipient wetness or excess solvent method. A deposition reaction such as hydrolysis may also be applied to bring the catalytically active metal or precursor thereof into contact with the catalyst carrier material. It is not particularly limited, and a compound of a catalytically active metal that may be selected from Co, Ni, Fe, W, V, Cr, Mo, Ce, Ag, Au, Pt, Pd, Ru, Rh, Cu, or mixtures thereof. Silver may be used in such an amount as to obtain a loading of 1-50% by weight, preferably 5-30% by weight, more preferably 8-20% by weight, in terms of oxides of the total weight of the final catalyst carrier material .

Accordingly, the present invention encompasses the following.

- the content of at least one compound selected from oxides of Si, Al and Zr, calculated as oxides, in an amount of 2-50% by weight, preferably 2-30% by weight, based on the total weight of the oxides anatase titanium dioxide having a sulfur content of less than 150 ppm, preferably less than 100 ppm, more preferably less than 80 ppm, based on the total weight of the oxide;

- the content of at least one compound selected from oxides of Si, Al and Zr in terms of oxides in an amount of 3-20% by weight, preferably 4-12% by weight, based on the total weight of the oxides, the total amount of the oxides anatase titanium dioxide having a sulfur content of less than 150 ppm, preferably less than 100 ppm, more preferably less than 80 ppm by weight;

- in terms of oxide, the content of SiO ₂ has an amount of 2-30% by weight, preferably 3-20% by weight, more preferably 4-12% by weight, based on the total weight of the oxide, to the total weight of the oxide for anatase titanium dioxide having a sulfur content of less than 100 ppm, preferably less than 80 ppm;

- the content of at least one compound selected from oxides of Si, Al and Zr, calculated as oxides, is 2-50% by weight, preferably 2-30% by weight, more preferably in the total weight of the oxides has an amount of 3-20% by weight, most preferably 4-12% by weight, and has a sulfur content of less than 150 ppm, preferably less than 100 ppm, more preferably less than 80 ppm, relative to the total weight of the oxide. A method for producing anatase titanium dioxide of the invention, wherein in an aqueous medium, a titanium compound selected from metatitanic acid or titanium sulfate is selected from oxides and/or hydroxides of Si, Al and Zr or precursors thereof mixed with at least one compound that is used to precipitate at least one compound selected from oxides and/or hydroxides of Si, Al and Zr, - if the content of alkali with respect to the total weight of the oxides exceeds 200 ppm, The product obtained is treated so as to reduce the content of For a time sufficient to decompose to a level of less than 150 ppm, preferably less than 100 ppm, more preferably less than 80 ppm relative to the total weight of a method in which calcination is preferably performed at a temperature of 800°C to 1200°C;

- A method for producing anatase titanium dioxide of an embodiment of the present invention, wherein metatitanic acid is mixed with a SiO ₂ precursor compound, and at least one of oxides and/or hydroxides of Si is precipitated, and the amount of alkali is based on the total weight of the oxide If the content exceeds 200 ppm, the obtained product is treated so as to reduce the content of alkali to a level of up to 200 ppm, the obtained product is selectively filtered, optionally washed, the obtained product is optionally dried, and then , for a time sufficient to decompose residual sulfur containing compounds such as sulfuric acid to a level of less than 100 ppm, preferably less than 80 ppm, based on the total weight of the oxide, preferably for 0.5 to 12 hours, the product is 500 a method in which calcination is carried out at a temperature above °C, preferably between 800 °C and 1200 °C;

- A method for producing anatase titanium dioxide, wherein a titanium compound selected from TiO ₂ sol is mixed with SiO ₂ sol, pH is adjusted to obtain a precipitate, and the content of alkali with respect to the total weight of the oxide If this exceeds 200 ppm, the obtained precipitate is treated so as to reduce the content of alkali to a level of up to 200 ppm, the obtained product is optionally filtered, optionally washed, optionally dried, and the obtained product is sulfuric acid for a time sufficient to decompose residual sulfur-containing compounds, such as, to a level of less than 150 ppm, preferably less than 100 ppm, more preferably less than 80 ppm, based on the total weight of the oxide, preferably 0.5 to 12 hours a method in which calcination is carried out at a temperature above 500° C., preferably between 800° C. and 1200° C.;

- a method for reducing the sulfur content of stabilized anatase titania, having a content of a stabilizing agent, wherein the anatase titania contains residual sulfur containing compounds such as sulfuric acid, 150 by total weight of the oxide For a time sufficient to decompose to a level of less than ppm, preferably less than 100 ppm, more preferably less than 80 ppm, preferably for at least 30 minutes, at a temperature above 500° C., preferably at a temperature between 800° C. and 1200° C. , wherein the stabilizer is selected from oxides of Si, Al and Zr, calculated as oxides, the content of the stabilizer is in the range of 2-50% by weight of the total weight of the oxide, preferably preferably in the range of 2-30% by weight;

- stabilized anatase titania having a content of at least one compound selected from oxides of Si, Al and Zr in an amount of 2-50% by weight, preferably 2-30% by weight, in terms of oxides, based on the total weight of the oxides the use of a calcination treatment at a temperature above 500° C. for reducing the sulfur content in the oxide to less than 150 ppm, preferably less than 100 ppm, more preferably less than 80 ppm, relative to the total weight of the oxide;

- Catalyst reactions, especially Fisher-Tropsch catalysts, selective catalytic reduction (SCR), oxidation catalysts, photocatalysts, hydrotreating catalysts, Klaus catalysts, phthalic acid catalysts, such as gaseous liquids The use of anatase titanium dioxide obtainable according to the process of the present invention for use as a catalyst or catalyst support in gas to liquid reactions.

- a catalyst or catalyst carrier containing anatase titanium dioxide obtainable according to the present invention or according to the process of the present invention.

The present invention is further illustrated by the following examples and comparative examples.

experimental part

analysis method

TiO ₂ Determination of polymorphs

To determine the TiO ₂ polymorph, X-ray diffraction (XRD) analysis is applied. This is done in a conventional XRD set-up in which the intensity of the diffracted X-rays is measured for a diffraction angle 2 theta. Evaluation of the obtained XRD pattern is performed using the JCPDS-database. The typical conditions of the analysis are as follows. 2 Theta = 10°~70°; 2 Theta's step-up angle (step) = 0.02°, measurement time per one step-up angle = 1.2 s.

SiO ₂ content measurement

The material is digested in H ₂ SO ₄ /(NH ₄ ) ₂ SO ₄ and diluted with deionized water. The residue is washed with sulfuric acid and the filter cake is weighed after calcination to obtain a SiO ₂ content.

TiO ₂ content measurement

Digestion of the material is performed using _H2SO4 /(NH ₄ ) ₂ SO ₄ or KHSO ₄ . The reduction of Ti ⁴⁺ to Ti ²⁺ is then carried out, and finally the TiO ₂ content is obtained by titration using ammonium iron(III) sulphate (ammonia iron(III) sulphate) (NH ₄ SCN as indicator).

Determination of S-content

The S-content is obtained by means of an elemental analyzer Euro EA (Hekatech). The sample is run in an oxygen environment, and the gas is analyzed by gas chromatography. The S-content is calculated from the area of the chromatogram.

Measurement of specific surface area

The specific surface area is determined by the nitrogen adsorption technique (BET method) according to DIN ISO 9277. Five points between 0.1 and 0.3 p/p _o are evaluated. The equipment used was Autosorb 6 or 6B (Quantachrome GmbH).

Example 1

SiO ₂ (13.1% by weight) was introduced by TiO ₂ and SiO ₂ co-precipitation from a solution containing TiOSO ₄ and Na ₂ SiO ₃ . 352 L (94 g/L SiO ₂ ) of Na ₂ SiO ₃ solution and 2220 L (103 g/L TiO ₂ ) of TiOSO ₄ solution were simultaneously pumped into a stirred reaction vessel containing 960 L water over a time period of 270 min. (pumped over). In the course of the reaction, the pH was maintained at 5 using ammonia solution. After the addition was complete, the reaction was heated to 75° C. for 1 hour to complete the reaction. Thereafter, hydrothermal aging was performed at 9.5-10 bar, 170-180° C. for 4 hours. Finally, the resulting reaction mixture was filtered and washed with deionized water. The product was obtained after spray drying at 350°C. BET was 100 m 2 /g and S content was 4000 ppm.

Example 2

Based on metatitanic acid and Na ₂ SiO ₃ , SiO ₂ /TiO ₂ powder with a SiO ₂ content of 8.5% by weight is prepared, followed by a pH-adjustment step, final filtration and washing of the material thus obtained with deionized water steps followed. The SiO ₂ /TiO ₂ powder obtained after drying has a BET of 334 m 2 /g and a sulfur content of 1100 mg/kg.

Example 3

943 g (29.2% by weight of TiO ₂ ) of metatitanic acid was diluted to 150 g/L with deionized water. 78.5 g of ZrOCl ₂ x8H ₂ O were added and the temperature was raised to 50°C. Then, sodium silicate (Na ₂ SiO ₃ ) 68 mL (358 g/L SiO ₂ ) was added. After the addition was complete, aqueous NaOH (50 wt % NaOH) was added at 50° C. until the pH reached 5.25. The white precipitate was filtered off and washed with deionized water until the conductivity of the filtrate was less than 100 μS/cm. The remaining filter cake was dried at &lt;RTI ID=0.0&gt;105 C.&lt;/RTI&gt; The product had a BET-surface area of 329 m 2 /g and an S content of >1000 ppm. SiO ₂ and ZrO ₂ contents were 7.7 wt% and 10.8 wt%, respectively.

Example 4

Example 4 was carried out in the same manner as in Example 3, except that the order of addition of ZrOCl ₂ x8H ₂ O and sodium silicate was changed. For Example 4, the Na ₂ SiO ₃ solution was added first, followed by ZrOCl ₂ x8H ₂ O. The contents of SiO ₂ and ZrO ₂ were 6.8 wt% and 10.4 wt%, respectively. The BET-surface area was 302 m 2 /g and the S-content was 3300 ppm.

Comparative Example 1

Hombikat 8602 (commercial product). The BET surface area was 321 m 2 /g and the S content was 4700 ppm.

Comparative Example 2

The commercially available Hombikat 8602 was purified by neutralization with NaOH and washing with deionized water. As a result of purification, the sulfur content before calcination was 0.2 wt % (2000 ppm), and the BET-surface area was 351 m 2 /g.

Comparative Example 3

A rutile suspension was prepared according to example 1a of DE 10333029A1. To prepare a rutile suspension, NaOH was added to pH 6.0, 6.2 at 60° C., the solid was filtered and washed with deionized water until the conductivity of the filtrate was less than 100 μS/cm. The resulting filter cake was re-slurried and spray dried. The BET surface area was 105 m 2 /g and the S-content was 70 ppm.

Comparative Example 4

As received, commercially available Aerosil P25 (from Evonik). The BET surface area was 55 m 2 /g and S < 30 ppm.

Comparative Example 5

Titanium oxychloride (Titaniumoxychloride) 300 mL (145 g/L TiO ₂ ) was diluted to 3 L using deionized water. Then, 4 g of oxalic acid dihydrate was added, and the reaction mixture was treated with a 15% aqueous solution of NaOH while maintaining the temperature below 20° C. to precipitate a white solid. The final pH was 6.2. After filtration, the white solid was washed with deionized water so that the filtrate conductivity was <100 μS/cm. Re-slurry and spray drying were performed to obtain a final product with BET: 359 m 2 /g, S < 30 ppm.

calcination

All calcinations were performed in a muffle kiln. The material was placed inside ceramic seggars (corundum) and heated at 1000° C. for 1 hour. The resulting powder was carefully ground and homogenized prior to XRD, BET and SO ₄ analysis. Table 1 shows the BET surface area and sulfur content of various SiO ₂ -treated TiO ₂ anatase carriers before and after aging at 1000° C. for 1 hour.

Fisher-Tropsch synthesis (FTS)

FTS tests were performed using a 32-fold parallel reactor. The powder was compressed and then crushed. Samples were lowered with Co(NO ₃ ) ₂ via impregnation so that the final Co loading could be 10 wt % based on the total weight of the dried and reduced catalyst. For the catalyst testing, fractions of 125-160 μm were used, and each catalyst unit was charged with an amount of catalyst to ensure a 40 mg Co-metal loading. Before performing the catalyst tests, the catalysts were activated with diluted H ₂ (25% in Ar) at 350° C. (1 K/min heat ramp). Catalyst tests were then performed at 20 bar with a feed rate of 1.56 L/h per reactor. The H ₂ /CO ratio was 2 (10% Ar in the feed) and the temperature of the catalyst test was 220°C.

In the Fischer-Tropsch synthesis, CO and H ₂ were contacted at elevated pressure and temperature to react to form hydrocarbons. Evonik P25 is a known TiO ₂ based catalyst carrier for this application. In order to have an overall economical FTS process, the catalyst must satisfy the following characteristics. 1. High CO conversion (X _co , %). 2. High C ₅₊ productivity (productivity, Pc5+, g _C5+ /(g _co h)). 3. Low methane selectivity (S _CH4 , %). 4. Low CO ₂ selectivity (S _co2 , %).

The goal of FTS is to produce long chain hydrocarbons. In particular, hydrocarbons having more than 5 carbon atoms may contain more than 5 carbon atoms, as they serve as feedstocks, for example associated with high quality diesel, kerosene or long chain waxes. Eggplant hydrocarbons are of interest. By reacting methane with H ₂ O to obtain CO and H ₂ (steam reforming), synthesis gas (syngas, H ₂ /CO-mixture) is often produced from methane. Due to the reverse reaction, the amount of CO and H ₂ that can be used in connection with the FTS synthesis will be reduced. High methane (CH ₄ ) selectivity in FTS indicates high conversion of CO and H ₂ to CH ₄ and vice versa. Therefore, the CH ₄ selectivity should be kept as low as possible. Moreover, under the reaction conditions, CO must react with H ₂ O to form CO ₂ and H ₂ (water vapor shift reaction). This will reduce the concentration of carbon atoms that can be used in connection with the FTS. A high CO ₂ selectivity indicates a high conversion of CO to CO ₂ and vice versa. Therefore, the CO ₂ selectivity should be low with respect to the FTS catalyst.

Besides this, the CO conversion (amount of converted CO) must be high, moreover, the amount of hydrocarbons having more than 5 carbon atoms must also be high. The latter parameter is expressed by the amount of hydrocarbons having more than 5 carbon atoms produced in 1 hour per gram of metallic cobalt.

With regard to all these four parameters, Table 3 clearly shows that the product according to the invention exhibits excellent properties when used as catalyst carrier in FTS.

Raw materials used and physical properties Sample before calcination After calcining at 1000℃ for 1 hour BET, m2/g S, mg/kg TiO ₂ polymorph BET, m2/g S, mg/kg TiO ₂ polymorph Example 1 100 4000 anatase 60 40 anatase Example 2 334 1100 anatase 70 < 30 anatase Example 3 329 > 1000 anatase 77 < 30 anatase Example 4 302 3300 anatase 52 < 30 anatase Comparative Example 1 321 4700 anatase 3 < 30 rutile Comparative Example 2 351 2000 anatase 3 < 30 rutile

Analysis overview of carrier materials used for FTS Sample BET, m2/g S, mg/kg TiO ₂ , polymorph Example 1 (after 1 hour at 1000°C) 70 < 30 anatase Example 2 (After 1 hour at 1000°C) 77 < 30 anatase Example 3 (after 1 hour at 1000° C.) 52 < 30 anatase Comparative Example 3 105 70 rutile Comparative Example 4 55 < 30 anatase/rutile Comparative Example 5 359 < 30 anatase

Example Light Comparative Example Fischer-Tropsch Composite Data Sample X _co (%) S _CH4 (%) P _c5+ g _C5+ /(g _Co h) S _co (%) Example 2 54 7.2 3.46 0.6 Example 3 55.2 7.8 3.35 0.7 Example 4 52.9 7.7 3.3 0.6 Comparative Example 3 12.6 9.4 0.74 n.d. Comparative Example 4 20.6 9.5 1.18 n.d. Comparative Example 5 0.5 31.3 0.02 n.d. n.d. = CO conversion too low to be determined (not determined).

The catalyst test and the above-described results according to the Examples and Comparative Examples of the present invention show that the excellent catalytic properties of these materials due to the combination of properties of the materials of the present invention, that is, high specific surface area and anatase content, and low sulfur content, are shown. show

Claims (12)

The content of at least one compound selected from oxides of Si, Al and Zr, calculated as oxides, has an amount of 2-50% by weight based on the total weight of the oxides, and sulfur with respect to the total weight of the oxides Anatase titanium dioxide with a content of less than 150 ppm and a BET surface area greater than 40 m ² /g.
The method of claim 1,
In terms of oxides, anatase having a content of at least one compound selected from oxides of Si, Al and Zr in an amount of 3-20% by weight based on the total weight of the oxides, and having a sulfur content of less than 150 ppm with respect to the total weight of the oxides titanium dioxide.
The method of claim 1,
Anatase titanium dioxide, wherein the content of SiO ₂ in terms of oxide is 2-30% by weight based on the total weight of the oxide, and the sulfur content is less than 100 ppm with respect to the total weight of the oxide.
the content of at least one compound selected from oxides of Si, Al and Zr, calculated as oxides, in an amount of 2-50% by weight with respect to the total weight of the oxides, the sulfur content with respect to the total weight of the oxides A method for preparing anatase titanium dioxide having a BET surface area of less than 150 ppm and greater than 40 m ² /g, the method comprising:
- in an aqueous medium, a titanium compound selected from metatitanic acid or titanium sulfate is mixed with at least one compound selected from oxides and/or hydroxides of Si, Al and Zr or precursors thereof,
- precipitating at least one compound selected from oxides and/or hydroxides of Si, Al and Zr,
- if the content of alkali with respect to the total weight of the oxide exceeds 200 ppm, treating the obtained product so as to reduce the content of alkali to a level of up to 200 ppm;
- the product is optionally filtered, optionally washed with water, and optionally dried,
the product is then calcined at a temperature of 800°C to 1200°C for 0.5 to 12 hours to decompose residual sulfur-containing compounds, such as sulfuric acid, to a level of less than 150 ppm relative to the total weight of the oxide; method.
A method for producing anatase titanium dioxide according to claim 3, comprising:
When metatitanic acid is mixed with the SiO ₂ precursor compound, precipitates at least one of oxides and/or hydroxides of Si, and the content of alkali exceeds 200 ppm with respect to the total weight of the oxide, the content of alkali is reduced to a level of up to 200 ppm The obtained product is treated so as to be reduced to wherein the product is calcined at a temperature of 800° C. to 1200° C. for 0.5 to 12 hours to allow decomposition to a level of less than 100 ppm.
A method for producing anatase titanium dioxide according to claim 3, comprising:
TiO ₂ Titanium compound selected from sol (sol) is mixed with SiO ₂ sol, pH is adjusted to obtain a precipitate, and when the content of alkali exceeds 200 ppm with respect to the total weight of the oxide, the content of alkali is The precipitate obtained is treated to reduce it to a level of up to 200 ppm, the product obtained is optionally filtered, optionally washed and optionally dried, and the product obtained is free of residual sulfur-containing compounds such as sulfuric acid of the oxides. A method in which calcination is carried out at a temperature of 800° C. to 1200° C. for 0.5 to 12 hours to enable decomposition to a level of less than 150 ppm by total weight.
A method for reducing the sulfur content of stabilized anatase titania, comprising:
Anatase titania having a content of a stabilizing agent is present in an amount of 0.5 to 12 to allow the decomposition of residual sulfur containing compounds, such as sulfuric acid, to a level of less than 150 ppm based on the total weight of the stabilized anatase titania. time, treated at a temperature of 800°C to 1200°C,
wherein said stabilized anatase titania after said treatment has a BET surface area of greater than 40 m ² /g;
The stabilizer is selected from oxides of Si, Al and Zr,
The method, calculated as oxides, wherein the content of the stabilizer is in the range of 2-50% by weight of the total weight of the stabilized anatase titania.
A method of treating stabilized anatase titania at a temperature exceeding 500° C. to reduce the sulfur content in the stabilized anatase titania to less than 150 ppm relative to the total weight of the stabilized anatase titania, comprising: Anatase titania is a method in which the BET surface area exceeds 40 m ² /g.
8. A catalyst or catalyst support in catalytic reactions, gas to liquid reactions, as described in any one of claims 1 to 3, or as any one of claims 4 to 7 A process using anatase titanium dioxide obtainable according to the process according to any one of the preceding claims.
10. The method according to claim 9, as a catalyst or catalyst carrier in a Fisher Tropsch catalyst, a selective catalytic reduction (SCR) catalyst, an oxidation catalyst, a photocatalyst, a hydrotreating catalyst, a Claus catalyst, a phthalic acid catalyst A method of using the anatase titanium dioxide.
Catalyst containing anatase titanium dioxide, obtainable according to the process according to any one of claims 1 to 3, or obtainable according to the process according to any one of claims 4 to 7.
A catalyst carrier comprising anatase titanium dioxide, obtainable according to the method according to any one of claims 1 to 3, or obtainable according to the method according to any one of claims 4 to 7.