RU2472586C1 - Microspherical catalyst for reducing sulphur content in cracked gasoline and method for production thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to the oil refining industry and specifically to preparation of catalysts for cracking oil fractions. Described is a microspherical catalyst for reducing sulphur content in cracked gasoline, which contains ultrastable zeolite Y in a cation-decationated form and a matrix whose components are bentonite clay, aluminium hydroxide, amorphous aluminosilicate and a magnesium-aluminium spinel with molar ratio Mg:Al of (2-3):1 or a zinc-magnesium-aluminium spinel with molar ratio Zn:Mg:Al of (1-2):(1-2):1, with the following content of components, wt %: zeolite Y 15-25; bentonite clay 15-25; aluminium hydroxide 15-25; amorphous aluminosilicate 25-40; magnesium-aluminium or zinc-magnesium-aluminium spinel 5-15. Described is a method of preparing said catalyst, involving ion exchange of ammonium cations and rare-earth elements on zeolite Y, ultrastabilisation of the zeolite in water vapour medium, mixing the zeolite with matrix components in form of bentonite clay, aluminium hydroxide, amorphous aluminosilicate and magnesium-aluminium hydrotalcite with molar ratio Mg:Al of (2-3):1 or zinc-magnesium-aluminium hydrotalcite with molar ratio Zn:Mg:Al of (1-2):(1-2):1, obtaining a composition and spray drying, followed by calcination.

EFFECT: low content of sulphur in cracked gasoline while maintaining high output of gasoline.

2 cl, 2 tbl, 8 ex

Description

The present invention relates to the refining industry, and in particular to the preparation of microspherical cracking catalysts to reduce the sulfur content of cracked gasoline.

A traditional vacuum gas oil cracking catalyst does not allow a low sulfur content in cracking gasoline. When using traditional cracking catalysts, approximately 10% of the vacuum gas oil sulfur is contained in cracked gasoline.

Known additives for cracking catalysts to reduce the sulfur content of cracked gasoline (US Pat. No. 5,376,608, No. 5,525,210) based on Lewis solid acid compositions. To reduce the sulfur content by 20-25%, it is necessary to add 10% of the additive by weight of the main catalyst to the main catalyst. The disadvantage of such compositions is the dilution of the catalytic system and a decrease in its activity.

Known additives for cracking catalysts to reduce the sulfur content of cracked gasoline (US patent No. 7347929, No. 7431825) based on compositions obtained from hydrotalcites. The disadvantage of such additives is also the dilution of the catalytic system and a decrease in its activity.

Known cracking catalysts for reducing the sulfur content in cracking gasoline containing in their composition more than 50% of a composite based on alumina modified with metals or their oxides selected from the group Ni, Cu, Ag, Cd, In, Zn and others (RF patents No. 2266782, No. 2396304). The disadvantage of such catalysts is the high content of the composite based on alumina.

A known catalyst coated with vanadium oxide to reduce the sulfur content of cracked gasoline (US patent No. 6482315, application for invention of the Russian Federation No. 20088140381). The disadvantage of this catalyst is that the supported vanadium oxide carries out undesired dehydrogenation reactions leading to an increased coke yield.

A known catalyst and method for its preparation, containing type Y zeolite, natural clay, aluminum oxide and an element selected from the group of yttrium, zinc, magnesium, manganese, rare earth elements or a combination thereof (application for invention of the Russian Federation No. 2007135321). The catalyst contains the specified element or a combination thereof in an amount of from 0.1 to 14 wt.%. The disadvantage of this catalyst is the low degree of sulfur reduction in cracked gasoline.

Closest to the proposed is a catalyst for cracking oil fractions and a method for its preparation (RF patent 2300420, prototype). The known catalyst contains ultrastable zeolite Y as an active component, and a mixture of bentonite clay, amorphous aluminosilicate and aluminum hydroxide as a matrix. The catalyst is prepared by conducting ion exchanges for cations of rare-earth elements and ammonium on NaY zeolite, ultra-stabilization of the zeolite in water vapor, mixing the zeolite with matrix components, followed by spray drying of the obtained composition from zeolite and matrix components, calcining and obtaining a catalyst. The disadvantage of this catalyst is the low degree of sulfur reduction in cracked gasoline.

An object of the present invention is to provide a cracking catalyst providing a high degree of sulfur reduction in cracking gasoline.

This goal is achieved due to the use of a component synthesized on the basis of the corresponding hydrotalcite, which, during calcination, turns into spinel. Spinel consists of the following oxides of divalent and trivalent elements: magnesium and aluminum, magnesium, zinc and aluminum.

The proposed microspherical catalyst for reducing the sulfur content in cracking gasoline includes ultra-stable zeolite Y in cation-decation form and a matrix using bentonite clay, aluminum hydroxide, amorphous aluminosilicate and magnesium aluminum spinel with a molar ratio Mg: Al (2-3) as components: 1 or zinc-magnesium aluminum spinel with a molar ratio of Zn: Mg: Al (1-2) :( 1-2): 1, with the following content of components, wt.%: Zeolite Y 15-25; bentonite clay 15-25; aluminum hydroxide 15-25; amorphous aluminosilicate 25-40, magnesium-aluminum or zinc-magnesium-aluminum spinel 5-15.

The proposed method for the preparation of a microspherical catalyst to reduce the sulfur content in cracking gasoline includes ion exchanges for ammonium cations and rare earth elements on zeolite Y, ultrastabilization of zeolite in water vapor, mixing zeolite with matrix components, which use bentonite clay, aluminum hydroxide, amorphous aluminum silicate and magnesium aluminum hydrotalcite with a molar ratio of Mg: Al (2-3): 1 or zinc-magnesium aluminum hydrotalcite with a molar ratio of Zn: Mg: Al (1-2) :( 1-2): 1, e composition and spray drying followed by calcination and obtaining a catalyst, and the content of components in the catalyst is, wt.%: zeolite Y 15-25; bentonite clay 15-25; aluminum hydroxide 15-25; amorphous aluminosilicate 25-40, magnesium-aluminum or zinc-magnesium-aluminum spinel 5-15.

The method of preparation of the catalyst is as follows.

Bentonite clay is subjected to activation by ammonium nitrate according to the ion exchange method to reduce the content of sodium oxide. After activation, the residual content of sodium oxide in the clay is less than 0.2 wt.%.

A suspension of the precipitated aluminum hydroxide is treated with concentrated nitric acid to peptize it. At this stage, part of the aluminum hydroxide is converted into basic nitric salts of aluminum, which ensures the strength of the resulting catalyst composition. Then mixed suspensions of activated bentonite clay and reprecipitated aluminum hydroxide in the required proportion. The main requirement for the implementation of this stage is the homogeneous mixing of the two suspensions.

Amorphous aluminosilicate is obtained by precipitation of sodium aluminate with acidic aluminum sulfate followed by syneresis, activation with aluminum sulfate and washing. The content of alumina in the amorphous aluminosilicate is from 10 to 16 wt.%, The content of sodium oxide is 0.1-0.2 wt.%.

Magnesium aluminum hydrotalcite is obtained by coprecipitation of Mg ²⁺ and Al ³⁺ ions with solutions of sodium hydroxide and sodium carbonate at a controlled temperature (50-70 ° C) and a precipitation pH (9.5-10.5).

Zinc magnesium aluminum hydrotalcite is obtained by coprecipitation of Zn ²⁺ , Mg ²⁺ and Al ^{3+ ions} with solutions of sodium hydroxide and sodium carbonate at a controlled temperature (50-70 ° C) and precipitation pH (9.5-10.5).

When calcining the catalyst, hydrotalcites turn into the corresponding spinels.

The synthesized zeolite NaY is subjected to double ion exchange for cations of rare earth elements and ammonium so that the zeolite before the stage of ultrastabilization contains 3.0-6.0 wt.% Rare earth elements (in terms of oxides) and 7.0-8.0 wt. % ammonium. The indicated content of rare-earth elements in the zeolite ensures the preservation of the crystallinity of the zeolite during its ultra-stabilization, and the content of ammonium cations before the ultra-stabilization stage and the temperature of the ultra-stabilization process provide zeolite with a given zeolite lattice constant. Ultra-stabilization of the zeolite is carried out in water vapor at temperatures from 450 to 650 ° C for 1 to 5 hours. Upon completion of the process of ultra-stabilization, the zeolite is subjected to a third ion exchange for cations of rare-earth elements, so that their content in the zeolite is from 10 to 12 wt.%.

A suspension of zeolite Y is added to the prepared composition bentonite clay - aluminum hydroxide - amorphous aluminosilicate - hydrotalcite. The mixture is filtered, molded into microspherical particles with a size of less than 0.25 mm. The resulting catalyst was dried and calcined.

Catalytic tests are carried out in a flow-through laboratory apparatus MAK-2M in accordance with ASTM D 3907-03 with a fixed catalyst bed.

The properties of the vacuum gas oil used for testing the catalysts are shown in table 1. The sulfur content in the vacuum gas oil is provided by adding to it an appropriate amount of benzothiophene.

The quantitative composition of gas products is determined on a gas chromatograph "CRYSTALLUX-4000M" equipped with a capillary column (ZB-5, 60 m × 0.32 mm × 1.00 μm, NLF: 5% phenyl-, 95% dimethylpolysiloxane) and the PFD / module PID detectors: flame photometric (PFD) - for the analysis of sulfur compounds and flame ionization (PID) - for the analysis of the hydrocarbon part. The total sulfur content in the feedstock and liquid cracking products is determined by X-ray fluorescence spectroscopy on an ARL OPTIM′X WD-XRF spectrometr (Thermo Techno) instrument. The concentration is determined by the intensity of the characteristic line S _Ka1,2 .

Table 1 Properties of Vacuum Gas Oil Raw material quality indicators Vacuum gas oil Density at 20 ° C, g / cm ³ 0.899 Fractional composition according to ASTM D-2887 (° C): 288 n.k. 357 10% 434 fifty% 523 90% 546 95% 561 (98%) c.k. Sulfur content, wt.% 1.28 Conradson coking ability, wt.% 0.12 Group chemical composition, wt.%: paraffin-naphthenic content fractions 46.0 aromatic content 52.0 resin content 2.0

The test results in accordance with the method ASTM D-3907-03 described catalysts are shown in table 2.

The following examples are provided to illustrate the invention.

Example 1 (prototype).

The following components are used in the preparation of the catalyst:

- a suspension of bentonite clay with a concentration of solid substance of 10.0 wt.%;

- a suspension of reprecipitated aluminum hydroxide pseudoboehmite modification with a concentration of 10.0 wt.% in terms of Al ₂ O ₃ ;

- a suspension of amorphous aluminosilicate with a solid concentration of 11 wt.%;

- a suspension of ultra-stable zeolite Y with a lattice constant of the zeolite of 24.65 Å and containing 15 wt.% solid. The content of rare earth elements before the stage of ultra-stabilization is 8.2 wt.%. The content of ammonium cations before the stage of ultrastabilization is 9 wt.%.

The suspensions are mixed in proportion so that the content of ultra-stable zeolite in the composition is 20 wt.%, Reprecipitated aluminum hydroxide 18 wt.% In terms of Al ₂ O ₃ , amorphous aluminosilicate 40 wt.% And bentonite clay 22 wt.%.

The resulting suspension is filtered, formed into microspherical particles with a size of less than 0.25 mm The catalyst is dried at a temperature of 100 ° C and calcined at 550 ° C.

The catalyst has a high gasoline yield, but the sulfur content of cracked gasoline is high.

Example 2. It characterizes the preparation of the catalyst according to the proposed method.

Magnesium aluminum hydrotalcite is obtained by coprecipitation of Mg ²⁺ and Al ³⁺ ions with solutions of sodium hydroxide and sodium carbonate at a controlled temperature (50-70 ° C) and precipitation pH (9.5-10.5).

To obtain a stoichiometric hydrotalcite, the molar ratio Mg: Al should be in the range of 2-3. Stock solutions of metal salts are obtained by dissolving the crystalline hydrates of magnesium nitrates [Mg (NO ₃ ) ₂ · 6H ₂ O] and aluminum [Al (NO ₃ ) ₃ · 9H ₂ O]. Prepare solutions with a concentration of 2.0 mol / L Mg (NO ₃ ) ₂ and 1.0 mol / L Al (NO ₃ ) ₃ , solutions of sodium hydroxide and sodium carbonate have a concentration of 2.2 mol / L.

Precipitation is carried out by simultaneous dosing into a container for precipitation of metal and precipitator solutions heated to 60 ° C with constant stirring. The missing amount of water to obtain a working concentration of 1.5 mol / l is preliminarily transferred to a container in which precipitation is carried out. The dosing rate of substances is selected based on the duration of the deposition of 4-6 hours.

At the end of the dosing of substances, the precipitated hydrotalcite in the mother liquor is aged at the same temperature for 12 hours, after which it is filtered and washed with plenty of water to remove sodium ions and nitrate ions.

A hydrotalcite suspension is prepared with a solid concentration of 10% by weight. and mixed with the suspensions of example 1 in a proportion so that the content of ultra-stable zeolite in the composition is 20 wt.%, reprecipitated aluminum hydroxide 18 wt.% in terms of Al ₂ O ₃ , amorphous aluminosilicate 35 wt.%, bentonite clay 22 wt.% and magnesium aluminum spinel 5 wt.%. Magnesium-aluminum spinel has a molar ratio of Mg: Al equal to 3: 1.

The catalyst has a high gasoline yield, the sulfur content in cracking gasoline is reduced compared to example 1, but has a high value.

Example 3. Similar to example 2, the difference is that the suspensions of the components are mixed in proportion, so that the content of ultra-stable zeolite in the composition is 20 wt.%, Reprecipitated aluminum hydroxide 18 wt.% In terms of Al ₂ O ₃ , amorphous aluminosilicate 30 wt. %, bentonite clay 22% by weight, and magnesium aluminum spinel 10% by weight. Magnesium-aluminum spinel has a molar ratio of Mg: Al equal to 2: 1.

The catalyst has a high yield of gasoline, the sulfur content in cracked gasoline is reduced compared to the prototype by more than 20%.

Example 4. Similar to example 2, the difference is that the suspensions of the components are mixed in proportion, so that the content of ultra-stable zeolite in the composition is 20 wt.%, Reprecipitated aluminum hydroxide 18 wt.% In terms of Al ₂ O ₃ , amorphous aluminosilicate 25 wt. wt.%, bentonite clay 22 wt.% and magnesium aluminum spinel 15 wt.%. Magnesium-aluminum spinel has a molar ratio of Mg: Al equal to 3: 1.

Example 5. Similar to example 4, the difference is that the suspensions of the components are mixed in proportion, so that the content of ultra-stable zeolite in the composition is 25 wt.%, Reprecipitated aluminum hydroxide 15 wt.% In terms of Al ₂ O ₃ , amorphous aluminosilicate 30 wt. %, bentonite clay 15% by weight, and magnesium aluminum spinel 15% by weight.

The catalyst has a high gasoline yield, the sulfur content in cracked gasoline is reduced by more than 30% compared with the prototype.

Example 6. It characterizes the preparation of the catalyst according to the proposed method.

Use zinc-magnesium aluminum spinel. The preparation of the catalyst is carried out as in example 2, the difference is that the suspensions of the components are mixed in proportion, so that the content of ultra-stable zeolite in the composition is 15 wt.%, Reprecipitated aluminum hydroxide 15 wt.% In terms of Al ₂ O ₃ , amorphous aluminosilicate 40 wt.%, bentonite clay 15 wt.% and zinc-aluminum spinel 15 wt.%. Zinc magnesium aluminum spinel has a molar ratio of Zn: Mg: Al equal to 1: 2: 1.

Example 7. Similar to example 6, the difference is that the suspensions of the components are mixed in proportion, so that the content of ultra-stable zeolite in the composition is 20 wt.%, Reprecipitated aluminum hydroxide 15 wt.% In terms of Al ₂ O ₃ , amorphous aluminosilicate 30 wt. wt.%, bentonite clay 25 wt.% and aluminum-magnesium spinel 10 wt.%. Zinc magnesium aluminum spinel has a molar ratio of Zn: Mg: Al equal to 2: 1: 1.

Example 8. Similar to example 6, the difference is that the suspensions of the components are mixed in proportion, so that the content of ultra-stable zeolite in the composition is 20 wt.%, Reprecipitated aluminum hydroxide 25 wt.% In terms of Al ₂ O ₃ , amorphous aluminosilicate 30 wt. wt.%, bentonite clay 15 wt.% and aluminum-magnesium spinel 10 wt.%. Zinc magnesium aluminum spinel has a molar ratio of Zn: Mg: Al equal to 1: 1: 1.

The catalyst has a high yield of gasoline, a decrease in the sulfur content of cracked gasoline in comparison with the prototype is about 38%.

Thus, as follows from the examples and table 2, catalyst samples containing magnesium-aluminum or zinc-magnesium-aluminum spinels, provide a significant reduction in the sulfur content in cracked gasoline while maintaining a high yield of gasoline.

table 2 Catalytic properties of catalyst samples Example The content of zeolite type Y, wt.% The content of aluminosilicate, wt.% The content of bentonite clay, wt.% The content of alumina, wt.% The content and type of spinel, wt.% Gasoline output Sulfur content in cracked gasoline, ppm. 1 (prototype) twenty 40 22 eighteen 0 47.4 930 2 twenty 35 22 eighteen 5
Mg: Al = 3: 1 47.9 825 3 twenty thirty 22 eighteen 10
Mg: Al = 2: 1 47.3 726 four twenty 25 22 eighteen fifteen
Mg: Al = 3: 1 47.2 628 5 25 thirty fifteen fifteen fifteen
Mg: Al = 3: 1 48,2 615 6 fifteen 40 fifteen fifteen 15 Zn: Mg: Al = 1: 2: 1 45.8 540 7 twenty thirty 25 fifteen 10
Zn: Mg: Al = 2: 1: 1 46.6 590 8 twenty thirty fifteen 25 10 Zn: Mg: Al = 1: 1: 1 47.1 580

Claims (2)

1. A microspherical catalyst for reducing the sulfur content in cracking gasoline, including ultra-stable zeolite Y in cation-decationized form and a matrix, the components of which are used bentonite clay, aluminum hydroxide and amorphous aluminosilicate, characterized in that the catalyst additionally contains magnesium aluminum as a matrix component spinel with a molar ratio of Mg: Al (2-3): 1 or zinc-magnesium aluminum spinel with a molar ratio of Zn: Mg: Al (1-2) :( 1-2): 1 with the following content of components, wt.%: zeolite Y 15 -25; bentonite clay 15-25; aluminum hydroxide 15-25; amorphous aluminosilicate 25-40, magnesium-aluminum or zinc-magnesium-aluminum spinel 5-15. 2. A method of preparing a microspherical catalyst to reduce the sulfur content in cracking gasoline, including ion exchanges for ammonium cations and rare earth elements on zeolite Y, ultra-stabilization of zeolite in water vapor, mixing zeolite with matrix components, which use bentonite clay, aluminum hydroxide and amorphous aluminosilicate, obtaining a composition and spray drying, followed by calcining and obtaining a catalyst, characterized in that at the stage of mixing the zeolite with the component Magnesium aluminum hydrotalcite with a molar ratio of Mg: Al (2-3): 1 or zinc-magnesium aluminum hydrotalcite with a molar ratio of Zn: Mg: Al (1-2) :( 1-2): 1 is additionally introduced with the matrix components, and the content of components in the catalyst is , wt.%: zeolite Y 15-25; bentonite clay 15-25; aluminum hydroxide 15-25; amorphous aluminosilicate 25-40, magnesium-aluminum or zinc-magnesium-aluminum spinel 5-15.