阅读说明：本技术 一种ts-1催化剂及其制备方法 (TS-1 catalyst and preparation method thereof ) 是由 张春元 郝子健 杨帆 于 2021-07-15 设计创作，主要内容包括：一种TS-1催化剂的制备方法,包括以下步骤：1)取硅溶胶、造孔剂、TS-1原粉,通过滚球成型,得到初级品A；2)初级品A在600-650℃条件下焙烧,得到初级品B；3)初级品B、改性剂A、水混合,在170-190℃条件下晶化,得到中间品C；4)中间体C经洗涤后,与改性剂B、水混合,在170-190℃条件下晶化,得到中间品D；5)中间品D经洗涤后,先烘干,然后在600-650℃条件下焙烧,得到TS-1催化剂。本发明通过将TS-1原粉、硅溶胶、造孔剂进行滚球成型、烘干、焙烧,且经过两次改性,得到的TS-1产品适合工业化长周期催化丙烯环氧化。(A preparation method of a TS-1 catalyst comprises the following steps: 1) taking silica sol, pore-forming agent and TS-1 raw powder, and forming by rolling balls to obtain a primary product A; 2) roasting the primary product A at the temperature of 600-650 ℃ to obtain a primary product B; 3) mixing the primary product B, the modifier A and water, and crystallizing at the temperature of 190 ℃ under 170-; 4) washing the intermediate C, mixing the intermediate C with the modifier B and water, and crystallizing at the temperature of 170-190 ℃ to obtain an intermediate D; 5) and (3) washing the intermediate product D, drying, and roasting at the temperature of 600-650 ℃ to obtain the TS-1 catalyst. The TS-1 product obtained by rolling ball forming, drying and roasting TS-1 raw powder, silica sol and pore-forming agent and modifying the rolling ball twice is suitable for industrial long-period catalytic propylene epoxidation.)

1. A preparation method of a TS-1 catalyst is characterized by comprising the following steps:

1) taking silica sol, pore-forming agent and TS-1 raw powder, and forming by rolling balls to obtain a primary product A;

2) roasting the primary product A at the temperature of 600-650 ℃ to obtain a primary product B;

3) mixing the primary product B, the modifier A and water, and crystallizing at the temperature of 190 ℃ under 170-;

4) washing the intermediate C, mixing the intermediate C with the modifier B and water, and crystallizing at the temperature of 170-190 ℃ to obtain an intermediate D;

5) and (3) washing the intermediate product D, drying, and roasting at the temperature of 600-650 ℃ to obtain the TS-1 catalyst.

2. The preparation method of the TS-1 catalyst according to claim 1, wherein the silica sol in step 1) is an ammonium silica sol with a concentration of 25-35 wt%, the pore-forming agent is sesbania powder, and the molar ratio of Ti to Si of the TS-1 raw powder is 1:25, the mass ratio of the silica sol to the pore-forming agent to the TS-1 is 1.2-1.5: 0.03-0.1: 1, the diameter of the obtained primary product A is 0.8-3.5mm, preferably 0.8-1.2mm and/or 2.5-3.5 mm.

3. The method of claim 1, wherein the calcination time in step 2) is 3 hours.

4. The method for preparing the TS-1 catalyst according to claim 1, wherein the modifier A in step 3) is one or more of monoethanolamine, diethanolamine, triethanolamine, triethylamine, tetrapropylammonium hydroxide, tetrapropylammonium bromide, n-propylamine, n-butylamine, and 1, 6-hexanediamine, and the primary product B, the modifier A, and water have a mass of 1: 0.01-0.1: 15-25, crystallizing for 72-96h in a self-rotation crystallization kettle at the rotating speed of 1 r/min.

5. The preparation method of the TS-1 catalyst according to claim 1, wherein the modifier B in step 4) is one or more of sodium hydroxide, sodium bicarbonate, ammonium carbonate and ammonia water, and the mass ratio of the intermediate C, the modifier B and water is 1: 0.01-0.1: 10-20, purifying in a self-rotation crystallization kettle for 72-96h at the rotating speed of 1 r/min.

6. The method for preparing the TS-1 catalyst according to claim 1, wherein the washing in the step 5) is performed by washing with deionized water to be neutral, the drying is performed by drying at 120 ℃ for 2h, and the calcination time is 3 h.

7. A TS-1 catalyst prepared by the process of any one of claims 1 to 6.

8. The TS-1 catalyst of claim 7, wherein the TS-1 catalyst is spherical and has a specific surface area of 350m or more²The volume of the pores is more than or equal to 0.35ml/g, the average pore diameter is 4-9nm, and the strength is more than or equal to 30N per particle.

Technical Field

The invention relates to the field of catalytic materials, and particularly relates to a TS-1 catalyst and a preparation method thereof.

Background

The titanium silicalite molecular sieve is a heteroatom molecular sieve, has unique advantages in the aspects of catalysis, shape selection, ion exchange and the like due to the regular pore channel structure, adjustable acidity and larger specific surface area, and particularly shows excellent catalytic performance in selective oxidation reaction.

TS-1 molecular sieves are an important class of titanium silicalite molecular sieves with MFI structure (US4410501), which are synthesized as H₂O₂The catalyst is an oxidant, can realize various important green oxidation catalysis processes, is applied to a cyclohexanone ammoximation production device with the load of more than 10 ten thousand tons per year, and has milestone significance in the aspect of industrial catalytic oxidation.

Propylene oxide is an important organic chemical product and is the third largest product of propylene derivatives, which is second only to polypropylene and acrylonitrile. The existing production process of propylene oxide mainly adopts a chlorohydrin method which takes propylene, chlorine and calcium hydroxide as raw materials, and the process produces a large amount of high-salinity wastewater as a byproduct, thereby being not in accordance with the development concept of green chemical industry. With the national requirements for high quality and environmental development of the chemical industry, the propylene dioxygen water oxidation method (HPPO method) which takes propylene and hydrogen peroxide as raw materials and TS-1 molecular sieve as a catalyst is a green new technology which is mainly developed in the propylene oxide industry in recent years because the HPPO method only produces water as a byproduct and reacts with high selectivity and high conversion rate of propylene oxide.

At present, two main types of propylene epoxidation catalysts are available, one is a microsphere TS-1 molecular sieve catalyst, the average diameter of which is only 50-60 micrometers, the particles are small, and the catalyst is difficult to fix and filter due to the small particles and is not suitable for continuous epoxidation processes of devices such as a fixed bed and the like; the other is a TS-1 molecular sieve strip catalyst which is mainly prepared in an extrusion strip form and can be used for a fixed bed epoxidation device, but the strength of the catalyst is only 60N cm, the scouring resistance of the catalyst is not strong, and the catalyst is not suitable for long-period industrial operation.

Patent CN111099614A discloses a method for preparing gel by mixing noble metal source, organic silicon source, hydrolytic agent and water, aging and drying the obtained gel; then mixing the obtained solid product with a template agent and water, and then carrying out hydrothermal treatment; the prepared catalyst is suitable for cyclohexene oxidation reaction, the maximum cyclohexene conversion rate is 36%, and the maximum selectivity of cyclohexanediol is 51%, which indicates that the catalyst is not suitable for preparing epoxy compounds by olefin epoxidation.

Patent CN111115653A provides a method for modifying a spray-formed microspherical titanium silicalite molecular sieve and application thereof, and the specific method is to add a binder silica sol into a molecular sieve mother liquor and adjust the pH of the mother liquor to 9-10 by concentrated nitric acid. And dropwise adding a titanium source into tert-butyl alcohol, and then adding a titanium ester tert-butyl alcohol solution into the molecular sieve mother liquor. And spray forming to obtain microspherical titanium silicalite molecular sieve catalyst. Preparing a modifier consisting of organic alkali and inorganic salt, mixing a catalyst which is not dried and roasted with a modification solution, placing the mixture in a crystallization kettle, treating the mixture at the temperature of 150-200 ℃ for 6-72 hours, filtering, washing, drying and roasting to obtain the modified microspherical titanium silicalite molecular sieve. The titanium silicalite molecular sieve prepared by the method only adopts a kettle type reactor and a slurry bed reactor to produce the propylene oxide, and is not suitable for a fixed bed process due to small particles.

Patent CN111036290A discloses a method for preparing a titanium silicalite molecular sieve for inhibiting the generation of byproducts in the propylene epoxidation process, which mainly comprises introducing a nonionic surfactant tween and alkali metal ions into the synthesis process of a titanium silicalite TS-1 catalyst to reduce the acidity of Ti active centers on the TS-1 molecular sieve, thereby inhibiting the hydrolysis and alcoholysis of PO and the generation of acetaldehyde, improving the selectivity of propylene oxide, and reducing the separation energy consumption of PO. However, the catalyst of the invention is powdery and has no formation, and is not suitable for a fixed bed continuous process.

Patent 107500310B discloses a preparation method of a nano hierarchical pore TS-1 molecular sieve catalyst, which specifically comprises adopting tetrapropylammonium hydroxide as a structure directing agent and synthesizing by a traditional hydrothermal or solvothermal method. The product has an ellipsoidal shape, and the average crystal grain size is 150-250 nm. The patent only prepares the TS-1 molecular sieve raw powder and does not realize the molding preparation process.

Patent 104028314A discloses a TS-1 raw powder spray forming, then carries on the organic silicon and alkali hydrothermal modification, increases the catalyst hydrophobic and fluidity, can prepare the molecular sieve crystal of several to tens of microns into 2-85 micron microsphere catalyst, solves the problems of the raw powder catalyst poor fluidity, poor hydrophobicity, easy wall sticking and filter clogging, but this catalyst still can not realize the fixed bed process because of the smaller particles.

Therefore, how to develop a TS-1 molecular sieve catalyst with high activity, high selectivity, high pore diameter, high specific surface area, high compressive strength, wear resistance, scouring resistance and small pressure drop is a problem which needs to be solved urgently in the industrialization of the HPPO method at present.

Disclosure of Invention

One of the purposes of the invention is to provide a preparation method of a TS-1 catalyst aiming at the defects of the prior art, and the TS-1 product obtained by performing ball rolling forming, drying and roasting on TS-1 raw powder, silica sol and a pore-forming agent and performing two-time modification is suitable for industrial long-period catalytic propylene epoxidation.

The second purpose of the invention is to provide a TS-1 catalyst which has high structural strength, is suitable for long-period operation under pressure of an industrial device (10 ten thousand tons/year), can effectively inhibit hydrolysis and alcoholysis of propylene oxide and ineffective decomposition of side products of aldehydes and hydrogen peroxide in the propylene epoxidation process, and has greatly prolonged stability and service life.

The technical scheme for realizing one purpose of the invention is as follows: a preparation method of a TS-1 catalyst comprises the following steps:

1) taking silica sol, pore-forming agent and TS-1 raw powder, and forming by rolling balls to obtain a primary product A;

2) roasting the primary product A at the temperature of 600-650 ℃ to obtain a primary product B;

3) mixing the primary product B, the modifier A and water, and crystallizing at the temperature of 190 ℃ under 170-;

4) washing the intermediate C, mixing the intermediate C with the modifier B and water, and crystallizing at the temperature of 170-190 ℃ to obtain an intermediate D;

5) and (3) washing the intermediate product D, drying, and roasting at the temperature of 600-650 ℃ to obtain the TS-1 catalyst.

Further, in the step 1), the silica sol is ammonium silica sol, the concentration is 25-35 wt%, the pore-forming agent is sesbania powder, and the molar ratio of the TS-1 raw powder Ti to Si is 1:25, the mass ratio of the silica sol to the pore-forming agent to the TS-1 is 1.2-1.5: 0.03-0.1: 1, the diameter of the obtained primary product A is 0.8-3.5mm, preferably 0.8-1.2mm and/or 2.5-3.5 mm.

Further, the roasting time in the step 2) is 3 hours.

Further, the modifier A in the step 3) is one or more of monoethanolamine, diethanolamine, triethanolamine, triethylamine, tetrapropylammonium hydroxide, tetrapropylammonium bromide, n-propylamine, n-butylamine and 1, 6-hexanediamine, and the primary product B, the modifier A and water have the mass of 1: 0.01-0.1: 15-25, crystallizing for 72-96h in a self-rotation crystallization kettle at the rotating speed of 1 r/min.

Further, in the step 4), the modifier B is any one or more of sodium hydroxide, sodium bicarbonate, ammonium carbonate and ammonia water, and the mass ratio of the intermediate C to the modifier B to the water is 1: 0.01-0.1: 10-20, purifying in a self-rotation crystallization kettle for 72-96h at the rotating speed of 1 r/min.

Further, in the step 5), washing is carried out by adopting deionized water until the solution is neutral, drying is carried out for 2 hours at the temperature of 120 ℃, and the roasting time is 3 hours.

The invention also aims to provide the TS-1 catalyst prepared by any one of the preparation methods.

Furthermore, the TS-1 catalyst is spherical, and the specific surface area is more than or equal to 350m²The volume of the pores is more than or equal to 0.35ml/g, the average pore diameter is 4-9nm, and the strength is more than or equal to 30N per particle.

Adopt above-mentioned technical scheme to have following beneficial effect:

1. the preparation method of the invention firstly utilizes silica sol and pore-forming agent to mix with TS-1 raw powder, and obtains the spherical primary product A by ball-rolling molding, and the diameter is controlled to be 0.8-3.5mm, thus increasing the flow of reaction liquid passing through the area of the catalyst fixed bed, reducing the pressure drop of the fixed bed and improving the capacity of the matched production device. The molar ratio of Ti to Si in the TS-1 raw powder is limited to adjust the number of active centers of the catalyst, so that when the number of active centers of titanium is too large, non-skeletal anatase is easily generated, and when the number of active centers of titanium is too small, the number of active centers of the catalyst is insufficient. Limiting the mass ratio of silica sol, pore-forming agent and TS-1 to 1.2-1.5: 0.03-0.1: the method comprises the following steps of 1, controlling the mass ratio of silica sol to TS-1 to ensure the structural strength of the catalyst, so that the catalyst is not easy to pulverize, if the ratio is too high, the activity of the catalyst is not good, if the ratio is too low, the strength of the catalyst is not enough, controlling the mass ratio of a pore-forming agent to TS-1 to adjust the pore structure, the pore diameter and the specific surface area of the catalyst, if the ratio is too low, the pore-forming effect is not good, active components cannot be fully utilized, and if the ratio is too high, the strength of the catalyst is easily influenced, and the catalyst is easy to break.

2. The primary product A obtained by ball forming in the preparation method is roasted at 650 ℃ through 600-plus, the catalyst has good activity and high strength in the temperature range, the template agent cannot be completely removed if the temperature is too low, a good pore channel structure cannot be formed, and the catalyst has no activity if the framework structure is damaged and is easy to collapse if the temperature is too high.

3. The primary product B obtained by roasting and the modifier A are crystallized at the temperature of 190 ℃ at 170 ℃, a better crystal form can be obtained in the temperature range, if the temperature is too low, crystallization time needs to be prolonged, if the temperature is too high, the crystal form can be damaged, the crystal form is not good, and the activity of the catalyst is influenced, and in addition, the template agent is easy to decompose and agglomerate when the temperature is too high.

4. The intermediate product C obtained by crystallization in the preparation method is washed and then crystallized again with the modifier B at the temperature of 190 ℃ in 170-plus-material mode for modification crystallization to obtain a better crystal form, and meanwhile, the surface of the crystal form is modified to reduce the decomposition of hydrogen peroxide and the surface acid point of the hydrogen peroxide and to reduce the ring-opening alcoholysis reaction of catalyzing propylene oxide and methanol.

5. The intermediate product D obtained by crystallization in the preparation method is washed, dried and then roasted at the temperature of 600-650 ℃. The catalyst has good catalytic activity after being roasted at 600-650 ℃, and the catalyst has good activity and high strength in the temperature range. If the temperature is too low, the residual modifier can not be removed, a good pore channel structure can not be formed, and if the temperature is too high, the framework is collapsed, and the catalyst has no activity.

6. The TS-1 catalyst prepared by the preparation method has white to milky color without powder falling, and the specific surface area of the obtained spherical TS-1 catalyst is more than or equal to 350m²/g, pore volume ≥ 0.35 ml-g. The average pore diameter is 4-9nm, the strength is more than or equal to 30N/particle, the wear rate is less than 1%, and the composite material has excellent high pore diameter ratio, high specific surface area, high compressive strength, wear resistance and scouring resistance.

The test of the applicant proves that the TS-1 catalyst provided by the invention can effectively inhibit the hydrolysis and alcoholysis of propylene oxide and the ineffective decomposition of side products aldehydes and hydrogen peroxide in the propylene epoxidation process, the propylene epoxidation conversion rate is more than or equal to 98%, the selectivity is more than or equal to 98%, the unit consumption is less than or equal to 0.25Kg/t, the expected life is more than or equal to 2 years, and the catalyst is suitable for the pressurized long-period operation of an industrial device (more than 10 ten thousand tons/year).

The following description will be further described with reference to specific embodiments.

Detailed Description

In the invention, the raw materials are all chemical reagents which are commercially available, and the purity is chemical purity or analytical purity.

Example 1

Preparation of TS-1 catalyst

1) Ammonium silica sol (30 wt%), sesbania powder, TS-1 raw powder (Ti: si 1:25) in a mass ratio of 1.2: 0.05: 1, mixing, and carrying out ball rolling molding on a ball rolling device at room temperature to obtain a spherical TS-1 catalyst primary product A with the weight of about 2000 g;

2) drying 2000g of the primary product A of the spherical TS-1 catalyst for 2 hours at 120 ℃, and then roasting for 3 hours at 600 ℃ to obtain a primary product B of the spherical TS-1 catalyst, wherein the weight of the primary product B is about 1000 g;

3) 1000g of the obtained spherical TS-1 catalyst primary product B, the modifier A, triethylamine and water are mixed according to the mass ratio of 1:0.06: 15, stirring the mixture for 3 hours at the temperature of 70 ℃, then transferring the mixture into a self-rotation crystallization kettle (5L), setting the rotating speed at 1r/min, crystallizing the mixture for 72 hours at the temperature of 170 ℃, filtering the mixture, washing the mixture to be neutral by distilled water, drying the mixture for 2 hours at the temperature of 120 ℃, and roasting the mixture for 3 hours at the temperature of 600 ℃ to obtain a spherical TS-1 catalyst intermediate product C with the weight of about 950 g;

4) mixing 950g of the obtained spherical TS-1 catalyst intermediate product C, a modifier B, sodium bicarbonate and water according to the mass ratio of 1:0.08:12, stirring for 3h at 70 ℃, then transferring to a self-rotation crystallization kettle (5L), setting the rotation speed at 1r/min, crystallizing for 72h at 170 ℃, filtering, washing with distilled water to neutrality, drying for 2h at 120 ℃, and roasting for 3h at 600 ℃ to obtain a spherical TS-1 catalyst intermediate product D with the weight of about 950 g;

5) and washing the obtained spherical TS-1 catalyst intermediate product D with deionized water to be neutral, drying the product for 2h at 120 ℃, and then roasting the product for 3h at 600 ℃ to obtain a spherical TS-1 catalyst product with the weight of about 920 g.

Proved by the applicant, the prepared spherical TS-1 catalyst has the specific surface area of 352 square meters per gram, the pore volume of 0.36ml/g, the average pore diameter of 5nm, the strength of 32N per particle, the propylene epoxidation conversion rate of 98.6 percent, the selectivity of 98.1 percent and the space velocity of 0.5M³H; the catalyst wear rate is 0.08 percent and the unit consumption is 0.245Kg/t through long-period catalytic performance evaluation; the deactivated catalyst was regenerated at 175 deg.C with a catalyst performance recovery of 96.1%.

Example 2

Preparation of TS-1 catalyst

1) Ammonium silica sol (30 wt%), sesbania powder, TS-1 raw powder (Ti: si 1:25) in a mass ratio of 1.2: 0.03: 1, mixing, and carrying out ball rolling molding on a ball rolling device at room temperature to obtain a spherical TS-1 catalyst primary product A with the weight of about 2500 g;

2) 2500g of the obtained spherical TS-1 catalyst primary product A is roasted for 3 hours at the temperature of 650 ℃ to obtain a spherical TS-1 catalyst primary product B with the weight of about 1200 g;

3) 1200g of the obtained spherical TS-1 catalyst primary product B, the modifier A, tetrapropylammonium hydroxide and water are mixed according to the mass ratio of 1: 0.04: 18, stirring for 3 hours at the temperature of 80 ℃, then transferring to a self-rotation crystallization kettle (5L), setting the rotating speed at 1r/min, crystallizing for 90 hours at the temperature of 175 ℃, filtering, washing with distilled water to be neutral, drying, and roasting for 3 hours at the temperature of 650 ℃ to obtain a spherical TS-1 catalyst intermediate product C with the weight of about 1100 g;

4) 1100g of the obtained spherical TS-1 catalyst intermediate product C, a modifier B, ammonium bicarbonate and water are mixed according to the mass ratio of 1:0.06:12, stirred for 3h at 80 ℃, then transferred into a self-rotation crystallization kettle (5L), crystallized for 100h at 175 ℃, filtered, washed to be neutral by distilled water and roasted for 3h at 600 ℃ to obtain a spherical TS-1 catalyst intermediate product D with the weight of about 1080 g;

5) and washing the obtained spherical TS-1 catalyst intermediate product D with deionized water to be neutral, drying the product for 2h at 120 ℃, and then roasting the product for 3h at 650 ℃ to obtain a spherical TS-1 catalyst product with the weight of about 1030 g.

The applicant verifies that the prepared spherical TS-1 catalyst has the specific surface area of 351 square meters per gram, the pore volume of 0.365ml/g, the average pore diameter of 6.5nm and the strength of 31N per granule; the epoxidation conversion rate of the propylene is 98.3 percent, the selectivity is 98 percent, and the space velocity is 0.5M³The wear rate of the catalyst is 0.085 percent and the unit consumption is 0.243Kg/t through long-period catalytic performance evaluation, the deactivated catalyst is regenerated at the temperature of 175 ℃, and the recovery rate of the catalytic performance is 95.2 percent.