CN105749963B - A kind of preparation method and catalyst of hysomer/Cracking catalyst - Google Patents

Abstract

The invention relates to a preparation method of a hydroisomerization/cracking catalyst. The specific steps are as follows: the sodium-type ZSM-22 molecular sieve containing the template is treated with a certain concentration of alkali solution; the obtained product is washed with deionized water, dried, and roasted to remove the template; then exchanged with ammonium nitrate solution, filtered, and washed with deionized water, dried and roasted to make hydrogen ZSM‑22 molecular sieve; kneading, molding and roasting hydrogen ZSM‑22 molecular sieve with amorphous oxide and acid solution to make carrier; impregnating the carrier in soluble salt in an aqueous solution, and then dried and calcined to obtain the catalyst. Compared with the catalysts used in the prior art, the catalyst provided by the invention has better catalytic activity and target product selectivity when used in the conversion process of Fischer-Tropsch synthesis wax.

Description

A kind of preparation method and catalyst of hydroisomerization/cracking catalyst

technical field

The invention belongs to the field of molecular sieve catalysts, in particular to a method for preparing a hydroisomerization/cracking catalyst based on ZSM-22 molecular sieves.

Background technique

Fischer-Tropsch synthesis (Fischer-Tropsch synthesis) is referred to as FT reaction, which uses syngas (CO and H ₂ ) as raw materials to synthesize liquids mainly composed of paraffin hydrocarbons under the catalyst (such as iron-based, cobalt-based, etc.) and appropriate reaction conditions. Fuel process. Traditional Fischer-Tropsch synthesis is characterized by wide distillation range distribution, high content of heavy hydrocarbons, and all of them are straight chain hydrocarbons. Such heavy alkanes have a high freezing point and are not suitable for direct use as diesel oil or lubricating oil. Therefore, the freezing point must be depressed. The most important means of depreciating normal paraffins is hydroisomerization and cracking, which converts long-chain normal paraffins into isoparaffins or small molecular paraffins with low freezing point by a dual-functional catalyst with special pores. The bifunctional catalyst consists of acid sites and metal sites, in which the acid sites are produced by molecular sieves with special pore structures, such as SAPO-11, ZSM-22, ZSM-23, ZSM-5, Beta, etc.

For heavy oil products with a wide distillation range distribution, all components cannot be converted into ideal target products only through isomerization reaction, for example, the freezing point and viscosity index cannot meet the requirements. Therefore, while isomerization occurs, it is necessary to properly crack some high-melting n-paraffin components that are not prone to isomerization reactions, so as to convert them into light diesel oil or low-point lubricating oil. Therefore, it is hoped that the catalyst has dual functions of isomerization and cracking at the same time. However, excessive cracking will also increase the light products sharply, and the yield of the target product (diesel or lubricating oil) will decrease, which not only reduces the performance of the product, but also reduces the yield, affecting economic benefits.

ZSM-22 molecular sieve is a kind of artificially synthesized high silicon molecular sieve, which belongs to TON topology, has a one-dimensional ten-membered ring channel structure, and the orifice size is It can be synthesized using different templating agents. For example, US4556477 discloses a method for synthesizing ZSM-22 molecular sieves using diethylamine hydrochloride as a template. US4902406, US5707600, US5783168, etc. disclose the method of synthesizing ZSM-22 molecular sieve by using 1,6-hexamethylenediamine as template.

The ZSM-22 molecular sieve synthesized by the conventional method has a high silicon-aluminum ratio, strong acidity and less acid content, and the micropores are the main channels of the molecular sieve. To meet the requirements of high isomerization activity and suitable cracking activity, ZSM-22 molecular sieve must have a suitable silicon-aluminum ratio (acidity) and a suitable pore size distribution, so as to promote the simultaneous progress of isomerization and cracking and the timely separation of reactants and products. desorption. Modification of ZSM-22 molecular sieve by post-treatment can adjust the silicon-aluminum ratio of the molecular sieve and produce some mesopores in the crystal of the molecular sieve, so as to meet the above reaction requirements.

Contents of the invention

The purpose of this invention is to provide a kind of preparation method of hydroisomerization-cracking catalyst.

The present invention is achieved through the following technical solutions:

(1) Treat the sodium-type ZSM-22 molecular sieve containing the template with an alkaline solution, wash the solid with deionized water until the eluent is neutral, dry and roast to remove the template; the solid product obtained is then washed with ammonium nitrate ( NH ₄ NO ₃ ) solution exchange, filter, and wash with deionized water, dry, and roast to make hydrogen ZSM-22 molecular sieve;

(2) kneading and molding the obtained hydrogen-type ZSM-22 molecular sieve with the amorphous oxide and acid solution, drying and roasting after natural drying to make a carrier;

(3) immersing the carrier in an aqueous solution of a soluble salt of Group VIII metal, drying it naturally, then drying and roasting to obtain the hydroisomerization/cracking catalyst.

The template agent in the sodium type ZSM-22 molecular sieve in the step (1) is one or more of diethylamine, 1,6-hexanediamine, 1-butylamine or ethanolamine, and the content is sodium type ZSM-22 0.5-30 wt.% of 22 molecular sieve.

The alkali solution in the step (1) is sodium hydroxide (NaOH) aqueous solution or potassium hydroxide (KOH) aqueous solution, and the concentration is 0.1-1.0mol/L; In the lye at 20-120°C, the treatment time is 10-600min. After treatment, filter and wash the solid with deionized water until the eluent is neutral.

The exchange with ammonium nitrate solution in the step (1) is to completely immerse the molecular sieve in the ammonium nitrate solution, stir, so that the sodium ions on the molecular sieve are replaced by ammonium ions, so that the sodium-type ZSM- 22 or potassium type ZSM-22 molecular sieves are exchanged for hydrogen type ZSM-22 molecular sieves; the concentration of the ammonium nitrate solution used is 0.1-1.0mol/L, and the amount of the solution is based on the fact that all the molecular sieves are below the liquid level; the exchange temperature with the ammonium nitrate solution is 20-100°C, the number of exchanges is 2-4 times, each time 1-8h; after each exchange, filter and wash with deionized water until the eluent is neutral.

The amorphous oxide in the step (2) is one or more of amorphous alumina or amorphous silica-alumina, and its mass ratio to hydrogen ZSM-22 molecular sieve is 1:10 to 10:1 .

The acid solution in the step (2) is an aqueous nitric acid solution or an aqueous acetic acid solution with a concentration of 0.1-1.0 mol/L; the amount of the acid solution added is 10%-100% of the total mass of the molecular sieve and the amorphous oxide.

The specific operation method of the above step (2) is: mix the hydrogen ZSM-22 molecular sieve obtained in the step (1) and the amorphous oxide evenly, and prepare and knead with an acid solution to form a carrier precursor; use an extruder, The carrier precursor is formed by a tablet press, etc.; the formed carrier precursor is naturally dried, dried, and roasted to form a carrier. The kneading temperature is room temperature, and the kneading time is 0.5-12h; the molding temperature is room temperature.

The aqueous solution of the VIII metal soluble salt in the step (3) is one or two or three nitrates, chloride salts, ammonium complex salts or carbonyl complex salts of platinum, palladium and iridium One or more of them; catalyst impregnation adopts equal-volume impregnation method, impregnation at room temperature for 2-12h.

All the solid products obtained need to be dried before the roasting operation in all the above steps, the drying temperature is 80-150°C, and the time is 2-8h; the roasting temperature is 300-700°C, and the time is 4-8h. 40h.

The content of Group VIII metals in the hydroisomerization/cracking catalyst finally prepared by the method provided by the invention is 0.1-5.0 wt.%.

The present invention adjusts the silicon-aluminum ratio of the molecular sieve by means of alkali treatment, so that the acid content of the molecular sieve is increased, and the acid strength distribution is adjusted; at the same time, the alkali treatment increases the intracrystalline mesopores of the molecular sieve. The mass transfer is improved, heavy linear alkanes are effectively converted, and the probability of further cracking of small molecule isomeric hydrocarbons is reduced.

Therefore, compared with the prior art, the present invention has the following advantages:

(1) The catalyst prepared by the present invention has excellent isomerization performance, and simultaneously has good cracking performance for heavy linear alkanes.

(2) The catalyst provided by the invention can significantly improve the freezing point of diesel and lubricating base oils.

(3) The catalyst prepared by the invention is particularly suitable for the conversion of Fischer-Tropsch wax, and can effectively increase the content of diesel oil and lubricating base oil in the process of converting Fischer-Tropsch wax.

Detailed ways

The present invention will be further described below in conjunction with specific examples, but it should be pointed out that the content of the present invention is not limited thereto.

Comparative example 1

Take 100g of sodium ZSM-22 molecular sieve after roasting at 550°C for 24h to remove the template, put it in 2L of NH ₄ NO ₃ solution with a concentration of 0.5mol/L, exchange it for 180min at 60°C, filter and wash with deionized water Wash until the eluent is neutral, exchange continuously (repeat the above operation) twice, dry at 120°C for 6h, and roast at 550°C for 24h to obtain hydrogen ZSM-22 molecular sieve (H-ZSM-22). Take 30g of alumina (γ-Al ₂ O ₃ ) and mix it evenly, add 80g of 5wt.% HNO ₃ solution, knead at room temperature for 2 hours, use an automatic extruder to extrude at room temperature, dry naturally, and then Dry for 4 hours, and bake at 550°C for 8 hours to obtain a molecular sieve support (H-ZSM-22 support). 100 g of the above support was impregnated with 10 mL of chloroplatinic acid (H ₂ PtCl ₆ ) solution containing 0.05 g/mL of platinum (Pt) to prepare a 0.5 wt.% Pt/H-ZSM-22 catalyst, coded as A1. The evaluation results of the catalytic reactions are shown in Table 2.

Example 1

Take 100g of sodium ZSM-22 molecular sieve containing 1,6-hexanediamine template, put it in 3L NaOH solution with a concentration of 0.2mol/L, treat it at 80°C for 180min, filter, and wash until the eluate is Neutral, dried and roasted to remove the template; the obtained product was placed in 2L of NH ₄ NO ₃ solution with a concentration of 0.5mol/L, exchanged for 180min at 60°C, filtered, and washed with deionized water until the eluent was medium In order to obtain the hydrogen type ZSM-22 molecular sieve (H-ZSM-22), it was exchanged twice (repeated the above operation) twice, dried at 120°C for 6 hours, and calcined at 550°C for 24 hours. Take 30g of alumina (γ-Al ₂ O ₃ ) and mix it evenly, add 80g of 5wt.% HNO ₃ solution, knead at room temperature for 2 hours, use an automatic extrusion machine to extrude at room temperature, dry naturally, and then dry at 120°C 4h, calcination at 550°C for 8h to obtain a molecular sieve carrier (H-ZSM-22 carrier). Impregnate 100 g of the above carrier with 10 mL of chloroplatinic acid (H ₂ PtCl ₆ ) solution containing 0.05 g/mL of platinum (Pt) to prepare a 0.5 wt.% Pt/H-ZSM-22 catalyst, coded as B1. The evaluation results of the catalytic reactions are shown in Table 2.

Example 2

Take 100g of sodium ZSM-22 molecular sieve containing 1,6-hexamethylenediamine template, put it in 3L NaOH solution with a concentration of 0.4mol/L, treat it at 80°C for 180min, filter, and wash until the eluate is Neutral, dried and roasted to remove the template; the obtained product was placed in 2L of NH ₄ NO ₃ solution with a concentration of 0.5mol/L, exchanged for 180min at 60°C, filtered, and washed with deionized water until the eluent was medium In order to obtain the hydrogen type ZSM-22 molecular sieve (H-ZSM-22), it was exchanged twice (repeated the above operation) twice, dried at 120°C for 6 hours, and calcined at 550°C for 24 hours. Take 30g of alumina (γ-Al ₂ O ₃ ) and mix it evenly, add 80g of 5wt.% HNO ₃ solution, knead at room temperature for 2 hours, use an automatic extrusion machine to extrude at room temperature, dry naturally, and then dry at 120°C 4h, calcination at 550°C for 8h to obtain a molecular sieve carrier (H-ZSM-22 carrier). Impregnate 100 g of the above carrier with 10 mL of chloroplatinic acid (H ₂ PtCl ₆ ) solution containing 0.05 g/mL of platinum (Pt) to prepare a 0.5 wt.% Pt/H-ZSM-22 catalyst, coded as B2. The evaluation results of the catalytic reaction are shown in Table 2.

Example 3

Take 100g of sodium ZSM-22 molecular sieve containing 1,6-hexamethylenediamine template, put it in 3L NaOH solution with a concentration of 0.6mol/L, treat it at 80°C for 180min, filter, and wash until the eluate is Neutral, dried and roasted to remove the template; the obtained product was placed in 2L of NH ₄ NO ₃ solution with a concentration of 0.5mol/L, exchanged for 180min at 60°C, filtered, and washed with deionized water until the eluent was medium In order to obtain the hydrogen type ZSM-22 molecular sieve (H-ZSM-22), it was exchanged twice (repeated the above operation) twice, dried at 120°C for 6 hours, and calcined at 550°C for 24 hours. Take 30g of alumina (γ-Al ₂ O ₃ ) and mix it evenly, add 80g of 5wt.% HNO ₃ solution, knead at room temperature for 2 hours, use an automatic extrusion machine to extrude at room temperature, dry naturally, and then dry at 120°C 4h, calcination at 550°C for 8h to obtain a molecular sieve carrier (H-ZSM-22 carrier). Impregnate 100 g of the above carrier with 10 mL of chloroplatinic acid (H ₂ PtCl ₆ ) solution containing 0.05 g/mL of platinum (Pt) to prepare a 0.5 wt.% Pt/H-ZSM-22 catalyst, coded as B3. The evaluation results of the catalytic reactions are shown in Table 2.

Example 4

Take 100g of sodium ZSM-22 molecular sieve containing 1,6-hexamethylenediamine template, put it in 3L NaOH solution with a concentration of 0.8mol/L, treat it at 80°C for 180min, filter, and wash until the eluate is Neutral, dried and roasted to remove the template; the obtained product was placed in 2L of NH ₄ NO ₃ solution with a concentration of 0.5mol/L, exchanged for 180min at 60°C, filtered, and washed with deionized water until the eluent was medium In order to obtain the hydrogen type ZSM-22 molecular sieve (H-ZSM-22), it was exchanged twice (repeated the above operation) twice, dried at 120°C for 6 hours, and calcined at 550°C for 24 hours. Take 30g of alumina (γ-Al ₂ O ₃ ) and mix it evenly, add 80g of 5wt.% HNO ₃ solution, knead at room temperature for 2 hours, use an automatic extrusion machine to extrude at room temperature, dry naturally, and then dry at 120°C 4h, calcination at 550°C for 8h to obtain a molecular sieve carrier (H-ZSM-22 carrier). Impregnate 100 g of the above support with 10 mL of chloroplatinic acid (H ₂ PtCl ₆ ) solution containing 0.05 g/mL of platinum (Pt) to prepare a 0.5 wt.% Pt/H-ZSM-22 catalyst, coded as B4. The evaluation results of the catalytic reaction are shown in Table 2.

Example 5

Take 100g of sodium ZSM-22 molecular sieve containing 1,6-hexamethylenediamine template, put it in 3L of NaOH solution with a concentration of 1mol/L, treat it at 80°C for 180min, filter, and wash until the eluate becomes medium nature, dried and roasted to remove the template agent; the obtained product was placed in 2L of NH ₄ NO ₃ solution with a concentration of 0.5mol/L, exchanged for 180min at 60°C, filtered, and washed with deionized water until the eluent was neutral , continuous exchange (repeat the above operation) twice, dry at 120°C for 6h, and roast at 550°C for 24h to obtain hydrogen ZSM-22 molecular sieve (H-ZSM-22). Take 30g of alumina (γ-Al ₂ O ₃ ) and mix it evenly, add 80g of 5wt.% HNO ₃ solution, knead at room temperature for 2 hours, use an automatic extrusion machine to extrude at room temperature, dry naturally, and then dry at 120°C 4h, calcination at 550°C for 8h to obtain a molecular sieve carrier (H-ZSM-22 carrier). Impregnate 100 g of the above carrier with 10 mL of chloroplatinic acid (H ₂ PtCl ₆ ) solution containing 0.05 g/mL of platinum (Pt) to prepare a 0.5 wt.% Pt/H-ZSM-22 catalyst, coded as B5. The evaluation results of the catalytic reactions are shown in Table 2.

Example 6

Take 100g of sodium ZSM-22 molecular sieve containing 1,6-hexamethylenediamine template, put it in 3L of NaOH solution with a concentration of 1mol/L, treat it at 80°C for 240min, filter, and wash until the eluate becomes neutral. nature, dried and roasted to remove the template agent; the obtained product was placed in 2L of NH ₄ NO ₃ solution with a concentration of 0.5mol/L, exchanged for 180min at 60°C, filtered, and washed with deionized water until the eluent was neutral , continuous exchange (repeat the above operation) twice, dry at 120°C for 6h, and roast at 550°C for 24h to obtain hydrogen ZSM-22 molecular sieve (H-ZSM-22). Take 30g of alumina (γ-Al ₂ O ₃ ) and mix it evenly, add 80g of 5wt.% HNO ₃ solution, knead at room temperature for 2 hours, use an automatic extrusion machine to extrude at room temperature, dry naturally, and then dry at 120°C 4h, calcination at 550°C for 8h to obtain a molecular sieve carrier (H-ZSM-22 carrier). Impregnate 100 g of the above carrier with 10 mL of chloroplatinic acid (H ₂ PtCl ₆ ) solution containing 0.05 g/mL of platinum (Pt) to prepare a 0.5 wt.% Pt/H-ZSM-22 catalyst, coded as B6. The evaluation results of the catalytic reaction are shown in Table 2.

Example 7

Take 100g of sodium ZSM-22 molecular sieve containing 1,6-hexamethylenediamine template, put it in 3L of NaOH solution with a concentration of 1mol/L, treat it at 60°C for 240min, filter, and wash until the eluate becomes neutral. nature, dried and roasted to remove the template agent; the obtained product was placed in 2L of NH ₄ NO ₃ solution with a concentration of 0.5mol/L, exchanged for 180min at 60°C, filtered, and washed with deionized water until the eluent was neutral , continuous exchange (repeat the above operation) twice, dry at 120°C for 6h, and roast at 550°C for 24h to obtain hydrogen ZSM-22 molecular sieve (H-ZSM-22). Take 30g of alumina (γ-Al ₂ O ₃ ) and mix it evenly, add 80g of 5wt.% HNO ₃ solution, knead at room temperature for 2 hours, use an automatic extrusion machine to extrude at room temperature, dry naturally, and then dry at 120°C 4h, calcination at 550°C for 8h to obtain a molecular sieve carrier (H-ZSM-22 carrier). Impregnate 100 g of the above carrier with 10 mL of chloroplatinic acid (H ₂ PtCl ₆ ) solution containing 0.05 g/mL of platinum (Pt) to prepare a 0.5 wt.% Pt/H-ZSM-22 catalyst, numbered B7. The evaluation results of the catalytic reactions are shown in Table 2.

Example 8

Take 100 g of sodium ZSM-22 molecular sieve containing 1,6-hexanediamine template, put it in 3 L of NaOH solution with a concentration of 1 mol/L, treat it at 60 °C for 180 min, filter, and wash until the eluate becomes medium nature, dried and roasted to remove the template agent; the obtained product was placed in 2L of NH ₄ NO ₃ solution with a concentration of 0.5mol/L, exchanged for 180min at 60°C, filtered, and washed with deionized water until the eluent was neutral , continuous exchange (repeat the above operation) twice, dry at 120°C for 6h, and roast at 550°C for 24h to obtain hydrogen ZSM-22 molecular sieve (H-ZSM-22). Take 30g of alumina (γ-Al ₂ O ₃ ) and mix it evenly, add 80g of 5wt.% HNO ₃ solution, knead at room temperature for 2 hours, use an automatic extrusion machine to extrude at room temperature, dry naturally, and then dry at 120°C 4h, calcination at 550°C for 8h to obtain a molecular sieve carrier (H-ZSM-22 carrier). Impregnate 100 g of the above carrier with 10 mL of chloroplatinic acid (H ₂ PtCl ₆ ) solution containing 0.05 g/mL of platinum (Pt) to prepare a 0.5 wt.% Pt/H-ZSM-22 catalyst, numbered B8. The evaluation results of the catalytic reactions are shown in Table 2.

Example 9

Catalytic reaction evaluation:

Raw material: Fischer-Tropsch synthetic heavy diesel oil, properties are shown in Table 1; Reaction conditions: 10mL fixed bed reactor, reaction temperature 330°C, reaction pressure 8MPa, space velocity 1h-1, hydrogen-oil ratio 600nL/nL. The evaluation results of each catalyst are listed in Table 2.

Table 1. Raw oil properties

Table 2. Product properties and evaluation results corresponding to different catalysts

Compared with the comparative example, the catalyst prepared by the present invention can obtain higher isomerization selectivity and target product (such as diesel oil) yield, thereby further improving the performance of oil products (such as freezing point depression), and simultaneously making the catalytic process Economical increase.

Claims (9)

1. A preparation method of hydroisomerization/cracking catalyst, characterized in that: comprise the steps: (1) Treat the sodium-type ZSM-22 molecular sieve containing the template with an alkali solution, exchange the solid product obtained after roasting with ammonium nitrate solution, and prepare the hydrogen-type ZSM-22 molecular sieve after roasting; (2) kneading and molding the obtained hydrogen ZSM-22 molecular sieve with amorphous oxide and acid solution, and then roasting to obtain the carrier; (3) impregnating the obtained support in an aqueous solution of a Group VIII metal soluble salt, and then roasting to obtain a hydroisomerization/cracking catalyst; The alkaline solution in the step (1) is an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution with a concentration of 0.1-1.0 mol/L; the molecular sieve is treated with alkaline solution, that is, the molecular sieve is completely immersed at a temperature of 20-120 ^o C In the alkaline solution, the treatment time is 180-600 min. After the treatment, the solid is washed with deionized water until the eluent is neutral. 2. The method according to claim 1, characterized in that: the template agent in the sodium ZSM-22 molecular sieve in the step (1) is diethylamine, 1,6-hexamethylenediamine, 1-butylamine or One or more of ethanolamines, the content is 0.5-30 wt.% of sodium ZSM-22 molecular sieve. 3. The method according to claim 1, characterized in that: in the step (1), the ammonium nitrate solution is used to completely immerse the molecular sieve in the ammonium nitrate solution at a temperature of 20-100 ^o C, and stir to make the molecular sieve The sodium ions on the surface are replaced by ammonium ions; the concentration of ammonium nitrate solution is 0.1-1.0 mol/L, and the number of exchanges is 2-4 times, each time 1-8h; after each exchange, filter and wash with deionized water until washing Dehydration was neutral. 4. The method according to claim 1, characterized in that: the amorphous oxide in the step (2) is one or more of amorphous alumina or amorphous silica-alumina, which is mixed with hydrogen The mass ratio of ZSM-22 molecular sieve is 1:10 to 10:1. 5. The method according to claim 1, characterized in that: the acid solution in the step (2) is an aqueous nitric acid solution or an aqueous acetic acid solution with a concentration of 0.1-1.0 mol/L; the amount of the acid solution added is molecular sieve and amorphous 10%-100% of the total mass of oxides. 6. The method according to claim 1, characterized in that: the aqueous solution of the VIII group metal soluble salt in the step (3) is one or two or three nitrates of platinum, palladium and iridium, One or more of chloride salts, ammonium complex salts or carbonyl complex salts; Catalyst impregnation adopts equal volume impregnation method, impregnation at room temperature for 2-12h. 7. The method according to claim 1, characterized in that: in step 2, the kneading temperature is room temperature, and the kneading time is 0.5-12h; the molding temperature is room temperature. 8. The method according to claim 1, characterized in that: the obtained solid product needs to be dried before the roasting operation, the drying temperature is 80-150 ^o C, and the time is 2-8h; The temperature is 300-700 ^o C, and the time is 4-40 h. 9. A hydroisomerization/cracking catalyst prepared by any method of claims 1-8, characterized in that: the content of Group VIII metals in the catalyst is 0.1-5.0 wt.%.