RU2276621C1 - Hydrocarbon conversion catalysts and a method for preparation thereof - Google Patents

Abstract

FIELD: catalyst preparation methods.

SUBSTANCE: invention, in particular, relates to catalyst based on synthetic mesoporous crystalline materials and provides hydrocarbon conversion catalyst composed of: group VIII metal/SO₄ ²-/ZrO₂-EOx, where E represents element of the group III or IV of Mendeleev's periodic table, x = 1.5 or 2, content of SO₄ ²- is 0.1 to 10% by weight, ZrO₂/EOx molar ratio is 1:(0.1-1.0), which has porous crystalline structure with specific surface 300-800 m²/g and summary pore volume 0.3-0.8 cm³/g. Preparation method comprises precipitation of zirconium compounds, in particular zirconium hydroxide or zirconyl, under hydrothermal conditions in presence of surfactant to form mesoporous phase, which is stabilized with stabilizing agents: group III and IV elements. When stabilization is achieved, if necessary, acidity is adjusted and group VIII metal is added.

EFFECT: increased specific surface area and heat resistance at simplified technology.

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Description

FIELD OF THE INVENTION

The invention relates to catalysts for the conversion of hydrocarbons and, in particular, relates to catalysts for the conversion of hydrocarbons based on synthetic mesoporous crystalline materials and the method for their preparation. The proposed catalysts can be used in the processes of isomerization of light gasoline fractions, isodeparaffinization of diesel and oil fractions, alkylation of isoalkanes with alkenes, hydrocracking and other oil refining processes.

State of the art

Currently, researchers are focusing on the development of zirconium oxide-based catalyst systems modified with anionic additives and containing Group VIII metals that outperform well-known catalysts used in various fields of oil refining and petrochemicals.

It is known that the activity of hydrocarbon conversion catalysts increases with increasing concentration of active centers. This can be achieved by increasing the specific surface area of the catalyst, as well as increasing the availability of active sites to the molecules of the reagent with increasing pore radius.

Known sulfated zirconium oxide catalyst obtained by the traditional method, including the deposition of a gel of zirconium oxide from zirconyl salts, its impregnation with ammonium sulfate, calcination at 500 ° C and the application of metals of group VIII by wet impregnation (VCFHolm, GCBailey, US Patent No. 3032599). The resulting catalyst has a relatively low activity, which is associated with a low specific surface area (~ 100 m ² / g).

A known method for the synthesis of sulfated zirconium oxide catalysts containing group VIII metals, which is a modification of the traditional precipitation-impregnation method in the form of replacement of ammonium sulfate with a solution of sulfuric acid while maintaining the remaining stages, which leads to the formation of a catalyst with a specific surface area of up to 150 m ² / g (K .Matsuzawa, EP 0925830). The disadvantage of the catalyst obtained by this method is the relatively low activity.

A known method of producing a catalyst, including the formation of a gel of zirconium oxide by washing and maintaining the reaction mixture in acetone or methanol, or by co-precipitation of hydrated zirconium oxide and aluminum, subsequent impregnation with ammonium sulfate and the deposition of platinum on an oxide carrier by impregnation by moisture capacity (G. Szabo, P. Nascimento, A. Milan, S. Decker, J. Denayer, J.-P. Dath, U.S. Patent No. 6,448,198). The specific surface area of the catalysts obtained by this method is 150-160 m ² / g, the total pore volume is up to 0.2-0.25 cm ³ / g with a pore diameter of up to

A known method for the synthesis of sulfated zirconium oxide catalyst containing an element of group VIII, based on the sol-gel method, including the synthesis of zirconium sol in an aqueous solution of ammonia in the presence of hydroxypropyl methylcellulose and starch, the formation of a microspherical or spherical structure of the gel, gelation, washing and drying followed by impregnation with an aqueous solution of ammonium sulfate and elements of group VIII and calcination at 450-700 ° C (M. Marella, M. Thomaselli, L. Maergalli, F. Pinna, US Patent No. 6180556). The specific surface area of the catalysts obtained by this method reaches 235 m ² / g, the total pore volume is 0.17 cm ³ / g with a pore diameter of 1.4-2.3 nm. The disadvantages of the catalysts obtained by the above methods include low thermal stability due to the inability to form a regular wide-pore structure with a controlled pore radius.

Удельная поверхность катализатора составляет 91-347 м²/г, а объем пор равен 0,16-0,31 см³/г. К недостаткам данного способа следует отнести то, что полученный катализатор мезопористой структуры не обладает достаточной стабильностью в процессе термообработки, а также использование дорогих и нетехнологичных исходных веществ (Zr(OPrⁱ)₄,) и процессов (а именно экстракция этанолом, центрифугирование).Closest to the proposed invention is a catalyst based on sulfated ZrO ₂ with a mesoporous structure prepared by a two-stage method (WMHSachtler, YYHuang, US Patent No. 5786294). At the first stage, hydrothermal crystallization of a mixture of Zr (OPr ⁱ ) ₄ and C ₁₆ H ₃₃ NH ₂ in a solution of water-ethanol-acetylacetone is carried out, the solid material is separated by centrifugation and the organic matrix is removed by extraction with ethanol. At the second stage, stabilization with an aqueous solution of sulfuric acid and calcination are carried out, followed by the application of Group VIII metals (Pt, Pd, Rh, Ru, Ni). A reflex corresponding to the interplanar spacing of

The specific surface area of the catalyst is 91-347 m ² / g and the pore volume is 0.16-0.31 cm ³ / g. The disadvantages of this method include the fact that the obtained catalyst of the mesoporous structure does not have sufficient stability during the heat treatment, as well as the use of expensive and low-tech starting materials (Zr (OPr ⁱ ) ₄ ,) and processes (namely, ethanol extraction, centrifugation).

Disclosure of invention

) и повышенной термической стабильностью, позволяющей выдерживать многократные циклы регенерации (например, удаление кокса прокаливанием на воздухе) при высоких температурах, а также способа получения катализатора исходя из выпускаемых в промышленности доступных крупнотоннажных продуктов.The proposed invention is aimed at creating a catalyst for the conversion of hydrocarbons based on mesoporous zirconium oxide containing a metal of group VIII of elements having a high specific surface (more than 200-300 m ² / g) and pore volume (not less than

) and increased thermal stability, allowing to withstand multiple regeneration cycles (for example, the removal of coke by calcination in air) at high temperatures, as well as a method for producing a catalyst based on available large-scale products produced in industry.

In accordance with this object of the proposed invention is a hydrocarbon conversion catalyst having the composition of a metal of group VIII / SO ₄ ^2- / ZrO ₂ -EO _x , where E = an element of group III or IV of the periodic table of D. I. Mendeleev, x = 1.5 or 2, the content of SO ₄ ^2- is 0.1-10 wt.%, the molar ratio of ZrO ₂ : EO _x = 1: (0.1-1.0), and having a mesoporous crystalline structure with a specific surface area of 300-800 m ² / g and a total pore volume of 0.3-0.8 cm ³ / g

Another object of the invention is a method for producing a hydrocarbon conversion catalyst, comprising precipitating zirconium compounds under hydrothermal conditions in the presence of a surfactant to obtain a mesoporous phase, stabilizing it with a stabilizing agent, calcining and introducing a metal of group VIII of the periodic table of D. I. Mendeleev, using zirconium compounds as zirconium or zirconyl hydroxide, group III or IV elements are used as a stabilizing agent, and after stabilization, if necessary carry out the regulation of acidity.

Preferably, zirconium or zirconyl hydroxide is prepared by precipitation of the corresponding salts from them.

In a particular embodiment, the zirconium or zirconyl hydroxide is preferably precipitated with aqueous ammonia.

In another particular case of the invention, the precipitation of zirconium or zirconyl hydroxide under hydrothermal conditions is carried out from the composition ZrO _a (OH) _b -H ₂ SO ₄ -H ₂ O, where a = 0-2, b = 0-4.

In the particular case of the invention, the metal of group VIII is introduced by ion exchange or impregnation.

In another particular embodiment of the invention, acidity is controlled by treating with aqueous solutions of acids and / or their salts, for example, using ammonium salts as salts.

The preferred mode of calcination of the catalyst is the temperature range of 450-900 ° C, while maintaining its porous characteristics.

Brief Description of the Drawings

Figure 1 presents the x-ray corresponding to the invention of the catalyst for the conversion of hydrocarbons based on zirconium oxide calcined in air at 550 °.

Figure 2 shows the pore size distribution for the catalyst based on the invention of the zirconium oxide calcined in air at 550 °, obtained from adsorption measurements.

The implementation of the invention

The catalyst preparation method includes, in a first step, preparing a composition consisting of hydrated zirconium oxide, sulfate anions and water, by precipitating a hydrated oxide phase from soluble zirconium or zirconyl salts, followed by their dissolution in concentrated sulfuric acid and dilution with water. The resulting composition is subjected to reprecipitation under hydrothermal conditions in the presence of cationic surfactants used as a matrix, with the formation of a mesoporous structure. At the second stage, the mesoporous structure is stabilized by treatment with compounds of group III-IV elements taken in certain relations to the mesoporous crystalline phase. In the third stage, if necessary, the acid-base properties of the mesoporous material are regulated by additional treatment with acids or their salts, and they are also calcined. At the fourth stage, metal of group VIII is applied by impregnation or ion exchange.

The preparation of the catalyst corresponding to the proposed invention is carried out in the following way.

At the first stage, the solution of the zirconium or zirconyl salt (ZrOCl ₂ , ZrO (NO ₃ ) ₂ ) is treated with aqueous ammonia in a molar ratio of 1 Zr: 4NH ₃ . The precipitate obtained is separated, washed with water, and then treated with sulfuric acid in a molar ratio of 1 Zr: (1.5-2.5) SO ₄ ^2- until the precipitate is completely dissolved. To the resulting solution is added an aqueous solution of a cationic surfactant of alkyltrimethylammonium halide ((C _n (CH ₃ ) ₃ NHal, where n = 10-20, Hal = Cl, Br)) in molar ratios of 1 Zr: (0.2-0.5) With _n (CH ₃ ) ₃ NHal: (400-600) H ₂ O and incubated at a temperature of 40-120 ° C for 20-100 hours. Upon completion of crystallization, the obtained mesoporous crystalline material based on zirconium oxide containing an organic matrix is filtered, washed and dried.

At the second stage, the mesoporous crystalline phase of zirconium oxide is stabilized. For this, a mixture containing the initial form of the mesoporous crystalline phase, the composition R ₄ NOH-SiO ₂ (Al ₂ About ₃ ) (where R = Me, Et) and water in a molar ratio of 1 Zr: (0.1-1.0): SiO ₂ (Al ₂ O ₃ ) :( 0.1-1.0) R ₄ NOH: (100-300) H ₂ O, maintained at a temperature of 40-100 ° C for 4-60 hours. Upon completion of crystallization, the initial the form of the mesoporous crystalline phase of zirconium oxide is filtered, washed and dried.

In the third stage, if necessary, the obtained material is treated with an aqueous solution of acids H _n A (for example, sulfuric, tungsten phosphoric, etc.) or their ammonium salts with a molar ratio of 1 ZrO ₂ : (0.01-0.1) A ^n- . The material is dried and calcined at a temperature of 500-700 ° C for 4-8 hours.

At the fourth stage, Group VIII metals are applied from aqueous solutions of chloride or ammonia complexes of Group VIII metals by ion exchange or impregnation. The resulting catalyst was dried and calcined at 400 ° C for 2 hours

(Фиг.1), что указывает на формирование структурированной мезопористой фазы. Данный рефлекс сохраняется после прокаливания при 550-600°С, что свидетельствует о сохранности мезопористой структуры. Средний диаметр пор заявляемого материала составляет

(Фиг.2).The obtained hydrocarbon conversion catalyst corresponding to the proposed invention significantly exceeds its known catalysts in terms of characteristics, namely, it has a specific surface area of 600-650 m / g and a total pore volume of 0.5-0.6 cm ³ / g. The chemical composition in molar ratio is 1 ZrO ₂ : (0.1-1.0) SiO ₂ (Ab ₂ O ₃ ) :( 0.01-0.1) SO ₄ ^2- : (0.0005-0.05 ) Group VIII metal. The X-ray diffraction pattern of the catalyst is characterized by the presence of a reflex corresponding to the interplanar distance

(Figure 1), which indicates the formation of a structured mesoporous phase. This reflex remains after calcination at 550-600 ° C, which indicates the preservation of the mesoporous structure. The average pore diameter of the claimed material is

(Figure 2).

The implementation of the proposed method for producing a catalyst corresponding to the proposed invention is illustrated by Examples 1-6. The conditions for the preparation of the catalyst are summarized in Table 1. The physicochemical characteristics of the catalysts obtained after calcination in air at 550 ° C, prepared in accordance with the proposed method, and the catalyst known from US Patent 5786294 are summarized in Table 2.

The catalysts of the invention were tested in the isomerization reaction of linear C ₄ -C ₇ alkanes. Before testing, the catalyst is reduced in a stream of hydrogen at a temperature of 200 ° C. All catalysts are highly active. In particular, the yield of isomers upon conversion of n-butane and n-hexane at 1 atm exceeds 30% and 70%, respectively.

Table 1.
Mesoporous Catalyst Preparation Conditions Example Source compound Matrix Deposition conditions Stabilization conditions Acidity regulation Metal application one ZrOCl ₂ Ctabr 48 h, 95 ° C Zr: Si = 1.7, 304, 90 ° С - H ₂ PtCl ₆ 2 ZrOCl ₂ CTACl 48 h, 95 ° C Zr: Si = 1.7, 304, 90 ° С - H ₂ PtCl ₆ 3 ZrOCl ₂ Ctabr 48 h, 95 ° C Zr: Si = 1.7, 304, 90 ° С H ₂ SO ₄ , S: Zr = 0.08 H ₂ PtCl ₆ four ZrOCl ₂ Ctabr 48 h, 95 ° C Zr: Si = 1.7, 304, 90 ° С (NH ₄ ) ₂ SO ₄ , S: Zr = 0.08 H ₂ PtCl ₆ 5 Zr (SO ₄ ) ₂ Ctabr 48 h, 95 ° C Zr: Si = 1.7, 304, 90 ° С (NH ₄ ) ₂ SO ₄ , S: Zr = 0.08 H ₂ PtCl ₆ 6 ZrOCl ₂ Ctabr 48 h, 95 ° C Zr: Si = 1.7, 304, 90 ° С (NH ₄ ) ₂ SO ₄ , S: Zr = 0.08 H ₂ PdCl ₄ Known method Zr (OPr) ₄ CNH ₂ 120 h, 20 ° C - H ₂ SO ₄ , 0.5 M solution, 15 ml / g _cat , 10 min Pt pd Note: CTABr is hexadecyltrimethylammonium bromide, CTACl is hexadecyltrimethylammonium chloride, CNH ₂ is hexadecylamine. Table 2.
Physico-chemical characteristics of mesoporous catalysts after calcination at 550 ° C Example Specific surface, m ² / g Pore volume, cm ³ / g one 601 ± 5 0.68 2 550 ± 6 0.55 3 566 ± 5 0.32 four 571 ± 5 0.63 5 599 ± 5 0.59 6 598 ± 5 0.60 Famous 215 ± 2 0.16

The measurement of the physicochemical characteristics of the target products was carried out as follows.

The specific surface and pore volume were measured on a Micromeritics ASAP 2020 adsorption porosimeter using nitrogen adsorption. The specific surface was calculated according to the BET model (Brunauer-Emmett-Teller) at a relative partial pressure P / P ₀ = 0.2. The total pore volume and pore radius distribution was calculated from the adsorption curve using the BJH (Barrett-Joyner-Halenda) model at a relative partial pressure of P / P ₀ = 0.99.

X-ray diffraction patterns of catalyst samples corresponding to the proposed invention were made on an X'Pert PRO PANAlytical device in monochromatized CuK _α radiation. The values of interplanar distances d were calculated using the formula d = λ / 2sinθ, where θ is the angle of the maximum of the reflection.

The catalytic activity of the samples was studied in the reactions of the conversion of linear C ₄ -C ₇ alkanes in a flow unit with a fixed catalyst bed at pressures of 0.1-3.5 MPa and temperatures of 160-380 ° C. The feed rate is 0.5-2 h ^-1 , the volume ratio of hydrogen: feed = 400-1000, the catalytic activity is tested 30 minutes after the establishment of the desired mode.

Example 1

The synthesis of the catalyst is carried out in four stages.

In the first step, 10.12 g (0.03 mol) of zirconyl chloride (ZrOCl ₂ · 8H ₂ O) is dissolved in 60 g of water. The resulting solution is treated with 4.4 ml of a 25% aqueous solution of NH ₄ OH until the hydrated oxide phase is completely precipitated. The precipitate was filtered off, washed on the filter with water and then treated with 6.16 g (0.06 mol) of concentrated sulfuric acid until the hydrated oxide phase was completely dissolved. To the resulting mixture was added 37.1 g of water. The resulting solution was added dropwise with vigorous stirring for 30 minutes to a surfactant solution containing 6.13 g (0.016 mol) of hexadecyltrimethylammonium bromide in 175 g of water. The mixture is maintained at a temperature of 95 ° C for 48 hours. The product was cooled to room temperature, separated by filtration, washed on the filter with water and dried at room temperature for 48 hours.

At the second stage, the mesoporous phase is stabilized. 10 g of the dry product obtained in the first step are suspended in 50 g of water. To the resulting suspension, with stirring, add a solution containing 2.93 g (0.045 mol) of silicon oxide, 32.96 ml of a 20% solution (0.045 mol) of tetraethylammonium hydroxide in water and 15 g of water. The molar ratio of Zr: Si is 1.7. The mixture is maintained at a temperature of 90 ° C for 30 hours. The product was cooled to room temperature, separated by filtration, washed on the filter with water and dried at room temperature for 48 hours.

In a third step, the catalyst is calcined at 550 ° C.

At the fourth stage, platinum is applied by the method of circulating impregnation from a solution of platinum hydrochloric acid. 10 g of the dry product obtained in the previous step are impregnated with 50 ml of a solution containing 0.05 g of platinum in the form of H ₂ PtCl ₆ . The impregnation is carried out for 1 hour at 50 ° C, then the solution is separated and the catalyst is dried at room temperature for 24 hours and at 100 ° C for 6 hours. The catalyst is calcined in an air stream at 400 ° C for 3 hours.

Example 2

The synthesis is carried out according to Example 1. At the first stage, as a surfactant, a mixture of 21.55 ml of a 25% solution of hexadecyltrimethylammonium chloride in 159 ml of water is used.

Example 3

The synthesis of the catalyst is carried out in four stages. The first, second and fourth stages are carried out according to Example 1.

In a third step, prior to calcination, acid properties are further adjusted. 10 g of the dry product obtained in the second stage is treated with a solution of 0.5 g (0.005 mol) of sulfuric acid in 50 g of water. The mixture was kept at room temperature for 1 hour, then evaporated and dried at 100 ° C for 2 hours. The product was calcined in a stream of air at 550 ° C for 6 hours.

Example 4

The synthesis is carried out according to Example 3. In the second stage, the molar ratio of Zr: Si is 1.7. The stabilization time is 30 hours. Acidity regulation in the third stage is carried out with a solution of 0.66 g (0.005 mol) of ammonium sulfate in 50 g of water.

Example 5

The synthesis is carried out according to Example 3 except that in the first stage, zirconium sulfate is taken as the starting compound.

In the first step, 15 g (0.042 mol) of Zr (SO ₄ ) 2 · 4H ₂ O are dissolved in 50 g of water. The resulting solution was added dropwise with vigorous stirring for 30 minutes to a solution of 8.24 g (0.021 mol) of hexadecyltrimethylammonium bromide in 235 g of water. The mixture is maintained at a temperature of 95 ° C for 48 hours. The product was cooled to room temperature, separated by filtration, washed on the filter with water and dried at room temperature for 48 hours.

The second, third and fourth stages are carried out according to Example 3.

Example 6

The first, second and third stages are carried out according to Example 3. At the fourth stage, palladium is applied from a solution of palladium hydrochloric acid. 10 g of the dry product obtained in the third stage are impregnated with 50 ml of a solution containing 0.05 g of Pd in the form of H ₂ PtCl ₄ . The impregnation is carried out for 1 h at 50 ° C. The solution was separated and the catalyst was dried at room temperature for 24 hours and at 100 ° C for 6 hours. The catalyst was calcined in a stream of air at 400 ° C for 3 hours.

Industrial applicability

), унифицированные по размерам, большие величины удельной поверхности и объема пор, а также возможность формирования специфических активных центров на внутренней поверхности пор.The catalysts corresponding to the proposed invention are of great interest for use in the processes of isomerization of light gasoline fractions, isodeparaffinization of diesel and oil fractions, alkylation of isoalkanes with alkenes, hydrocracking, etc. Interest is determined by high thermal stability and additional characteristics due to the features of the crystal structure combining wide pores ( over

), uniform in size, large specific surface area and pore volume, as well as the possibility of the formation of specific active centers on the inner surface of the pores.

Claims (9)

1. The catalyst for the conversion of hydrocarbons having a composition of a metal of group VIII / SO ₄ ^2- / ZrO ₂ -EO _x , where E = an element of group III or IV of the Periodic table of D. I. Mendeleev, x = 1.5 or 2, the content of SO ₄ ^2- is 0.1-10 wt.%, The molar ratio of ZrO ₂ : EO _x = 1: (0.1-1.0), and having a mesoporous crystalline structure with a specific surface area of 300-800 m ² / g and total volume then 0.3-0.8 cm ³ / g 2. A method of producing a catalyst for the conversion of hydrocarbons, including the precipitation of zirconium compounds under hydrothermal conditions in the presence of a surfactant to obtain a mesoporous phase, its stabilization with a stabilizing agent, calcination and introduction of a metal of group VIII of the Periodic Table of D. I. Mendeleev, characterized in that as zirconium compounds use zirconium or zirconyl hydroxide, elements of group III or IV are used as a stabilizing agent, and after stabilization, if necessary, they are regulated ment acidity. 3. The method according to claim 2, characterized in that the zirconium or zirconyl hydroxide is obtained by precipitation from their respective salts. 4. The method according to claim 3, characterized in that the zirconium or zirconyl hydroxide is precipitated with aqueous ammonia. 5. The method according to claim 2, characterized in that the precipitation of zirconium hydroxide or zirconyl under hydrothermal conditions is carried out from the composition of Zr _a O _b (OH) _c -H ₂ SO ₄ -H ₂ O. 6. The method according to claim 2, characterized in that the introduction of a metal of group VIII is carried out by ion exchange or impregnation. 7. The method according to claim 2, characterized in that the regulation of acidity is carried out with aqueous solutions of acids and / or their salts. 8. The method according to claim 7, characterized in that ammonium salts are used as salts. 9. The method according to claim 2, characterized in that the calcination is carried out at temperatures of 450-900 ° C.

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