CN111632620B - A medium oil type hydrocracking catalyst - Google Patents

Abstract

The invention discloses a medium-oil type hydrocracking catalyst and a preparation method thereof. The medium-oil type hydrocracking catalyst is prepared by using a modified Y molecular sieve subjected to simple hydrothermal treatment to solve the problem of middle distillate oil selectivity of existing catalysts. The problems of low yield and low liquid product yield can significantly improve the output income of the medium oil hydrocracking process.

Description

A medium oil type hydrocracking catalyst

technical field

The invention belongs to the technical field of catalyst preparation, and in particular relates to a medium oil type hydrocracking catalyst.

Background technique

The hydrocracking process is an oil refining process that converts high-boiling point raw materials into low-boiling naphtha, kerosene, diesel and other middle distillates. Compared with catalytic cracking, its raw material adaptability is high, and the yield of middle distillate is high and the quality is good. With the decline of the high-sulfur fuel oil market and the increasing social demand for clean transportation fuel oil, the hydrocracking process has become the core process of modern refineries.

Hydrocracking catalysts are typical dual-functional catalysts, which usually include dual-functional centers: one is a metal center, which is generally composed of a VIB group metal or a VIB-VIII binary metal system, and has the function of hydrogenation/dehydrogenation. Aromatic hydrocarbons are saturated; the second is the acid center with cracking function, which is provided by amorphous silica-alumina or molecular sieves (Y molecular sieves are most commonly used) to crack long-chain macromolecules.

When the hydrocracking catalyst prepared by conventional Y molecular sieve is used in the hydrocracking process, the middle distillate oil molecules, especially the kerosene fraction, tend to undergo deep cracking reactions in the micropore channels of the molecular sieve, and generate C1~C4 gaseous light hydrocarbons with low value. As a result, the selectivity of middle distillates in the product is not high, and the liquid product yield is on the low side. Therefore, there is a need to develop new hydrocracking catalysts with higher selectivity to middle distillates, especially diesel fractions.

Improve the pore structure of the hydrocracking catalyst to form more mesoporous channels, which is conducive to the rapid diffusion of primary cracking products from the micropore channels, reducing the probability of deep cracking reactions, thereby reducing the generation of low-value C1~C4 gaseous hydrocarbons , Improve middle distillate selectivity and liquid product yield. Since the cracking reaction usually occurs in the micropore channels of molecular sieves, forming mesopores on Y molecular sieves is the best way to modify the channel structure of catalysts. Usually use chemical methods, such as strong acid, strong base or complexing agent, to remove the silicon or aluminum on the part of the skeleton of Y molecular sieve, and then form the mesopores on the molecular sieve after high temperature heat treatment. At present, the ultra-stable Y molecular sieves used in hydrocracking catalysts have generally been dealuminated to adjust the strength and concentration of acid sites. Further strong chemical treatment will easily lead to a further decrease in the number of acid sites and affect the activity of the catalyst; at the same time, molecular sieves The further desiliconization or aluminum of the skeleton will easily lead to the reduction of crystallinity, reduce the thermal stability of the molecular sieve, and make the catalyst deactivate rapidly during the operation process.

Contents of the invention

Aiming at the problems of low selectivity to middle distillates and low yield of liquid products in existing medium-oil type hydrocracking catalysts, the present invention provides a novel medium-oil type hydrocracking catalyst and a preparation method thereof. The catalyst has high It is characterized by high activity, high middle distillate selectivity and high liquid yield.

To achieve the above object, the present invention adopts the following technical solutions:

One of the objects of the present invention is to provide a medium oil type hydrocracking catalyst, which comprises the following components:

(a) metals of group VIII elements or their oxides;

(b) metals of group VIB elements or their oxides;

(c) Amorphous silicon aluminum;

(d) aluminum oxide;

(e) Modified Y molecular sieve.

In the above technical solution, component (a) is 0.1-35 parts by weight, preferably 15-25 parts.

In the above technical solution, in parts by weight, component (b) is 0.1-10 parts, preferably 4-8 parts.

In the above technical solution, component (c) is 1-60 parts by weight, preferably 20-40 parts.

In the above technical solution, component (d) is 1-80 parts by weight, preferably 20-50 parts.

In the above technical solution, component (e) is 0.1-30 parts by weight, preferably 1-10 parts.

In the above technical solution, the group VIII element is selected from at least one of Co or Ni.

In the above technical solution, the VIB group element is selected from at least one of Mo or W.

In the above technical solution, the amorphous silicon-alumina is obtained by pre-calcining at 500°C for 4 hours in an air atmosphere; its specific surface area is 200-600 m ² /g, and its pore volume is 0.5-1.5 cm ³ /g, preferably 1.1~1.5 cm ³ /g; by weight percentage, SiO ₂ content is 20~80%.

In the above technical solution, the alumina is obtained by roasting pseudo-boehmite at 500°C for 4 hours in an air atmosphere; its specific surface area is 150-400 m ² /g, and its pore volume is 0.3-0.8 cm ³ /g, by weight percentage, Na element content ≤ 0.2%.

In the above technical solution, the modified Y molecular sieve is prepared by adding Y molecular sieve and ionic surfactant into ammonia water, fully stirring at room temperature, placing it in a high-pressure reactor for hydrothermal treatment, and then filtering and drying.

Wherein, the Y molecular sieve is a hydrogen molecular sieve with a specific surface area of 400-900 m ² /g, preferably 500-800 m ² /g; a total pore volume of 0.30-0.80 cm ³ /g, wherein the mesopore volume is less than 0.15 cm ³ /g, Si/Al molar ratio 5~30, unit cell size 24.25~24.45 .

The mass ratio of the Y molecular sieve and the ionic surfactant used is 1: (0.1~3); the ionic surfactant is specifically a cationic surfactant, preferably an ammonium salt or amine salt cationic surfactant, more preferably It is preferably at least one of cetyltrimethylammonium chloride (CTAC) and cetyltrimethylammonium bromide (CTAB).

The mass ratio of Y molecular sieve and ammonia water used is 1: (1-500); the content of ammonia monohydrate (NH ₄ OH) in the ammonia water is 0.5-5% in weight percentage.

The temperature of the hydrothermal treatment is 100-200° C., and the time is 1-48 h; the temperature of the drying is 80-200° C., and the time is 1-24 h.

Another object of the present invention is to provide a kind of method for preparing described middle oil type hydrocracking catalyst, it comprises the steps:

(1) Mix pseudo-boehmite, amorphous silica-alumina, and modified Y molecular sieve evenly, then add acid solution, fully knead and shape, then dry, then heat up to the roasting target temperature under nitrogen atmosphere and switch to air The atmosphere is roasted to obtain the catalyst carrier;

(2) Dispersing the compound containing VIB group elements and the compound containing VIII group elements in a solvent to impregnate the catalyst carrier obtained in step (1), then drying and roasting to obtain the medium-oil type hydrocracking catalyst.

In the above technical solution, the acid solution in step (1) can be inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid, or organic acids such as formic acid, acetic acid and citric acid; the concentration of the acid solution is 0.5wt%~5wt%, preferably 1wt% %~3wt%.

In the above technical solution, the size and shape of the molded catalyst in step (1) are preferably similar to traditional commercial hydrocracking catalysts, and it is more preferable to make a circular or clover cross-section with a diameter of 1.5-3.5 nm and a length of 3-12 nm. extrudate.

In the above technical solution, the drying temperature in step (1) is 80-200 °C, and the time is 2-24 h; the heating rate under nitrogen atmosphere is 1-20 °C/min, the target temperature is 400-650 °C, and the air The roasting time under the atmosphere is 3~12 h.

In the above technical solution, the compound containing group VIB elements and the compound containing group VIII elements described in step (2) are not particularly limited, and those skilled in the art can choose reasonably.

In the above technical solution, the solvent used in step (2) is not particularly limited, as long as the operation of impregnation and loading can be realized, these solvents can be dissolved directly, or dissolved by adjusting the pH, or can form colloids or be dissolved by adjusting the pH. Those solvents whose pH forms colloids may be a single solvent or a mixed solvent.

In the above technical solution, the drying temperature in step (2) is 80-200°C for 2-24 hours; the roasting temperature is 400-600°C for 2-12 hours.

The modification of the Y molecular sieve under relatively mild hydrothermal conditions in the present invention only needs simple filtration and separation, and can be directly used to prepare catalysts without high-temperature heat treatment. In this way, the pore structure of the molecular sieve can be improved without destroying the framework structure of the molecular sieve, so that more mesoporous channels can be formed in the prepared hydrocracking catalyst, which is conducive to the rapid diffusion of the primary cracking products from the micropore channels. Reduce the probability of deep cracking reactions, thereby reducing the generation of low-value C1~C4 gaseous hydrocarbons, and improving the selectivity of middle distillates and the yield of liquid products.

Compared with the existing hydrocracking catalyst, the medium oil type hydrocracking catalyst prepared by using the modified Y molecular sieve in the present invention can improve the selectivity of middle distillates on the basis of improving the activity of the catalyst, and the yield of liquid products is also increased accordingly. For medium-oil-type hydrocracking units, the output benefit can be significantly improved.

Detailed ways

In order to make the content of the present invention easier to understand, the technical solutions of the present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

The amorphous silicon-alumina used is pre-calcined at 500°C for 4 h in an air atmosphere; its specific surface area is 200-600 m ² /g, and its pore volume is 0.5-1.5 cm ³ /g; the content of SiO ₂ is 20% by weight. ~80%.

Example 1

Add 15.0 g of Y molecular sieve powder and 10.0 g of CTAC to 1000 g of ammonia water (NH ₄ OH content is 1wt%), stir thoroughly at room temperature for 30 minutes, then place in a high-pressure reactor, and conduct hydrothermal treatment at 170 °C for 24 h, and then filtered and dried at 120°C for 12 hours to obtain modified Y molecular sieve powder Y-1.

Example 2

Add 15.0 g of Y molecular sieve powder and 20.0 g of CTAC to 350 g of ammonia water (the content of NH ₄ OH is 2wt%), stir well at room temperature for 60 minutes, and then place it in a high-pressure reactor for hydrothermal treatment at 180°C 20 h, then filtered and dried at 140°C for 30 h to obtain modified Y molecular sieve powder Y-2.

Comparative example 1

Add 15.0 g of Y molecular sieve powder and 20.0 g of CTAC to 350 g of ammonia water (the content of NH ₄ OH is 2wt%), stir well at room temperature for 60 minutes, then filter and dry at 140°C for 30 hours to obtain modified Y Molecular sieve powder Y-3.

Table 1 shows the pore volume comparison results of Y molecular sieves and the prepared modified Y molecular sieves Y-1, Y-2, and Y-3 (before measuring the pore volume, Y, Y-1, Y-2, and Y-3 were all in the The temperature was raised to 560 °C under nitrogen atmosphere, then switched to air atmosphere and roasted for 6 hours).

Table 1 Comparison results of pore volumes of Y molecular sieves

It can be seen from Table 1 that compared with Y molecular sieves, the modified Y-1 and Y-2 molecular sieves have increased mesoporous pore volumes, especially the increase in the pores of 2-10nm is the most obvious, while only surfactant modification treatment The Y-3 molecular sieve has a slightly increased pore volume.

Example 3

Mix 10.0 g of the modified Y molecular sieve powder Y-1 prepared in Example 1, 10.0 g of amorphous silicon-alumina powder and 12.0 g of pseudo-boehmite powder evenly, then add 1.5wt% nitric acid solution, fully knead and squeeze The clover-shaped particles with a length of 3-10 mm and a diameter of 2 mm were dried at 140 °C for 10 hours, then heated to 560 °C under a nitrogen atmosphere and then switched to an air atmosphere for 6 hours to obtain the catalyst carrier S-1.

Example 4

Nickel nitrate (Ni(NO ₃ ) ₂ 6H ₂ O) enough to _{provide nickel oxide (NiO) and ammonium metatungstate ((NH 4 ) 10} W ₁₂ O ₄₁ x H ₂ O) was dispersed in deionized water, and then used to impregnate the catalyst carrier S-1 obtained in Example 3, then dried at 120 °C for 10 hours, and finally calcined at 550 °C for 6 hours to obtain the catalyst C-1.

Example 5

Mix 10.0 g of the modified Y molecular sieve powder Y-2 prepared in Example 2, 10.0 g of amorphous silicon-alumina powder and 12.0 g of pseudo-boehmite powder evenly, then add 1.5wt% nitric acid solution, fully knead and squeeze The clover-shaped particles with a length of 3-10 mm and a diameter of 2 mm were dried at 140 °C for 10 hours, then heated to 560 °C under a nitrogen atmosphere, then switched to an air atmosphere and calcined for 6 hours to obtain the catalyst carrier S-2.

Example 6

Nickel nitrate (Ni(NO ₃ ) ₂ 6H ₂ O) enough to _{provide nickel oxide (NiO) and ammonium metatungstate ((NH 4 ) 10} W ₁₂ O ₄₁ x H ₂ O) was dispersed in deionized water, and then used to impregnate the catalyst carrier S-2 obtained in Example 5, then dried at 120 °C for 10 hours, and finally calcined at 550 °C for 6 hours to obtain the catalyst C-2.

Comparative example 2

(1) Mix 10.0g of Y-3 powder prepared in Comparative Example 1, 10.0g of amorphous silica-alumina powder and 12.0g of pseudo-boehmite powder evenly, then add 1.5wt% nitric acid solution, fully knead and extrude Form clover-shaped particles with a length of 3-10 mm and a diameter of 2 mm, dry at 140 °C for 10 hours, then heat up to 560 °C under a nitrogen atmosphere and then switch to an air atmosphere for 6 hours to obtain the catalyst carrier S-3.

(2) Nickel nitrate ( _Ni (NO ₃ ) ₂ 6H ₂ O) enough to provide nickel oxide (NiO) and ammonium metatungstate ((NH ₄ ) ₁₀ W ₁₂ O ₄₁ x H ₂ O) was dispersed in deionized water, and then used to impregnate catalyst carrier S-3, then dried at 120 °C for 10 hours, and finally calcined at 550 °C for 6 hours to obtain catalyst C -3.

Comparative example 3

(1) Mix 10.0g Y molecular sieve powder, 10.0g amorphous silica-alumina powder and 12.0g pseudo-boehmite powder evenly, then add 1.5wt% nitric acid solution, fully knead and extrude into 3-10 mm long, Clover-shaped particles with a diameter of 2 mm were dried at 140 °C for 10 hours, then heated to 560 °C under a nitrogen atmosphere and then switched to an air atmosphere for 6 hours to obtain catalyst carrier S-4.

(2) Nickel nitrate ( _Ni (NO ₃ ) ₂ 6H ₂ O) enough to provide nickel oxide (NiO) and ammonium metatungstate ((NH ₄ ) ₁₀ W ₁₂ O ₄₁ x H ₂ O) was dispersed in deionized water, and then used to impregnate the carrier S-3 obtained in step (1), then dried at 120 °C for 10 hours, and finally calcined at 550 °C for 6 hours, catalyst C-4 was obtained.

Comparative example 4

(1) Mix 10.0g Y molecular sieve powder, 10.0g amorphous silica-alumina powder and 12.0g pseudo-boehmite powder evenly, then add 1.5wt% nitric acid solution, fully knead and extrude into 3-10 mm long, Clover-shaped particles with a diameter of 2 mm were dried at 140 °C for 10 hours, then heated to 560 °C in an air atmosphere and then calcined for 6 hours to obtain catalyst carrier S-5.

(2) Nickel nitrate ( _Ni (NO ₃ ) ₂ 6H ₂ O) sufficient to provide nickel oxide (NiO) and ammonium metatungstate ((NH ₄ ) ₁₀ W ₁₂ O ₄₁ x H ₂ O) was dispersed in deionized water, and then used to impregnate the carrier S-4 obtained in step (1), then dried at 120 °C for 10 hours, and finally calcined at 550 °C for 6 hours, the catalyst C-5 was obtained.

The pore volume results of the catalyst supports obtained in Examples 3 and 5 and Comparative Examples 2-4 are shown in Table 2.

Table 2 Pore volume of catalyst supports

It can be seen from Table 2 that compared with the carriers S-3, S-4 and S-5 prepared in the comparative example, the mesopore volume of the carriers S-1 and S-2 increased, especially the pores of 2-10nm increased the most. obvious.

Example 7

Catalyst performance evaluation was carried out using a one-pass 50 mL small-scale hydrogenation evaluation device. Before the evaluation, the catalyst was presulfurized with a gas mixture consisting of 5% H ₂ S and 95% H ₂ by volume. The raw material used to evaluate the performance of the catalyst is hydrocracking cycle oil, and its properties and reaction process conditions are shown in Table 3 and Table 4. The reaction temperature was adjusted as required to ensure that the conversion rate remained at 68% in mass percentage within 100 hours. The comparison results of the reaction performance of each catalyst are shown in Table 5.

Table 3 Properties of raw oil

Table 4 Reaction process conditions

Table 5 Catalyst evaluation results

It can be seen from Table 5 that at the same conversion rate, the activities of catalysts C-1 and C-2 are slightly better than those of the comparative example, and the difference is not large, but the selectivity of middle distillate oil, especially the selectivity of diesel oil fraction, is significantly improved (Increased by 3~4 percentage points), C1~C4 formation decreased, and the liquid yield also increased.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (7)

1. A medium oil type hydrocracking catalyst, characterized in that: comprising the following components: (a) metals of group VIII elements or their oxides; (b) metals of group VIB elements or their oxides; (c) Amorphous silicon aluminum; (d) aluminum oxide; (e) Modified Y molecular sieve; In parts by weight, component (a) is 15-25 parts, component (b) is 4-8 parts, component (c) is 20-40 parts, component (d) is 20-50 parts, Component (e) is 1 to 10 parts; The group VIII element is selected from at least one of Co or Ni; The VIB group element is selected from at least one of Mo or W; The amorphous silicon-alumina is obtained by pre-calcining at 500°C for 4 hours in an air atmosphere; The modified Y molecular sieve is obtained by adding Y molecular sieve and ionic surfactant into ammonia water, fully stirring at room temperature, placing it in a high-pressure reactor for hydrothermal treatment, and then filtering and drying; wherein, the Y molecular sieve, The mass ratio of the ionic surfactant to the ammonia water is 1:(0.1~3):(1~500), the temperature of the hydrothermal treatment is 100~200°C, and the time is 1~48 h. 2. The medium-oil type hydrocracking catalyst according to claim 1, characterized in that: the specific surface area of the amorphous silica-alumina is 200-600 m ² /g, the pore volume is 0.5-1.5 cm ³ /g, and In terms of weight percentage, the _SiO content is 20-80%. 3. The medium-oil type hydrocracking catalyst according to claim 1, characterized in that: the alumina is obtained by roasting pseudo-boehmite at 500°C for 4 h in an air atmosphere; its specific surface area is 150 ~400 m ² /g, pore volume 0.3~0.8 cm ³ /g, calculated by weight percentage, Na element content ≤0.2%. 4. The medium oil type hydrocracking catalyst according to claim 1, characterized in that: the Y molecular sieve used to prepare the modified Y molecular sieve is a hydrogen type molecular sieve, its specific surface area is 400~900 m ² /g, and the total pore volume is 0.30 ~0.80 cm ³ /g, of which the mesopore volume is less than 0.15 cm ³ /g, the Si/Al molar ratio is 5~30, and the unit cell size is 24.25~24.45 ; The ionic surfactant is specifically a cationic surfactant; In weight percentage, the content of ammonia monohydrate in the ammonia water is 0.5 ~ 5%; The drying temperature is 80-200°C, and the drying time is 1-24h. 5. medium oil type hydrocracking catalyst according to claim 1, is characterized in that: its preparation method comprises the steps: (1) Mix pseudo-boehmite, amorphous silica-alumina, and modified Y molecular sieve evenly, then add acid solution, fully knead and shape, then dry, then heat up to the roasting target temperature under nitrogen atmosphere and switch to air The atmosphere is roasted to obtain the catalyst carrier; (2) Dispersing the compound containing VIB group elements and the compound containing VIII group elements in a solvent to impregnate the catalyst carrier obtained in step (1), then drying and roasting to obtain the medium-oil type hydrocracking catalyst. 6. The medium-oil type hydrocracking catalyst according to claim 5, characterized in that: the drying temperature in step (1) is 80-200 °C, and the time is 2-24 h; the heating rate under nitrogen atmosphere is 1 ~20 ℃/min, the target temperature is 400-650 ℃, and the roasting time in air atmosphere is 3-12 h. 7. The medium-oil type hydrocracking catalyst according to claim 5, characterized in that: the drying temperature in step (2) is 80-200 °C, and the time is 2-24 h; the roasting temperature is 400-600 °C , the time is 2~12 h.