Alkali metal catalyst, its preparation and use

Abstract

The application discloses an alkali metal catalyst, and a preparation and application thereof. The carrier of the alkali metal catalyst contains an alkali metal salt and a silicate, and the total pore volume is not less than 0.2 mL / g. The alkali metal catalyst provided by the application has high propylene conversion rate and high 4MP1 selectivity; and the carrier strength of the metal catalyst is high, and the service life of the catalyst is improved.

Description

Technical Field

[0001] This invention relates to an alkali metal catalyst, its preparation, and its application. Background Technology

[0002] Supported alkali metal catalysts exhibit unique catalytic activity in reactions such as olefin double bond isomerization, Marvin addition, side-chain alkylation of aromatics, and heterocyclic carbon chain substitution. They can selectively produce products that are difficult to generate under acid catalysis. For example, alkali metal catalysts catalyze the dimerization of propylene to yield the thermodynamically unstable product 4-methyl-1-pentene (hereinafter referred to as 4MP1). However, 4MP1 is virtually impossible to obtain using acid catalysts. Furthermore, compared to acid catalysts, solid alkali catalysts do not deactivate due to rapid coking. In addition, alkali catalysts have lower requirements for ambient temperature and pressure than acid catalysts, significantly reducing the severity of process conditions. Therefore, solid alkali catalysts, especially solid superbase catalysts, have great application prospects.

[0003] 4MP1 is an important chemical raw material and organic synthesis intermediate. Poly(4-methyl-1-pentene) (PMP), a novel special thermoplastic material homopolymerized from 4MP1, possesses the characteristics of general polyolefin materials, as well as high transparency, high softening point, good dielectric properties, and chemical resistance. Therefore, PMP has a wide range of specialized applications, including the manufacture of release paper, medical devices, food packaging materials, and electronic components—high-value-added products. It is particularly useful in emerging fields such as 5G and high-end medical devices (artificial lungs).

[0004] The main production method for 4MP1 is the selective dimerization of propylene. Catalysts with high 4MP1 selectivity are primarily alkali metal-based, prepared by dispersing alkali metals on alkali metal carbonates and / or bicarbonates. Alkali metal salts such as potassium carbonate have low specific surface area and simple pore structures, resulting in low isomerization activity and high 4MP1 selectivity. Therefore, they are often used as excellent supports for propylene dimerization to 4MP1 catalysts. However, alkali metal salts such as potassium carbonate suffer from low activity leading to low propylene conversion and insufficient particle strength, resulting in catalyst fragility. To resolve the contradiction between improving activity and ensuring selectivity, and to improve catalyst strength while addressing these contradictions, catalyst modification is usually employed to enhance conversion efficiency. Catalyst modification mainly involves two aspects: support modification and the addition of additives. Support modification primarily refers to improving the pore structure and pore size distribution of the support, while additives refer to the addition of alkaline earth metal oxides such as copper, cobalt, stainless steel powder, and MgO during catalyst preparation.

[0005] Catalysts are the core of the propylene dimerization to 4MP1 technology. Therefore, it is particularly important to develop a high-strength catalyst that combines high propylene conversion and high 4MP1 selectivity. Summary of the Invention

[0006] In order to at least partially improve the catalyst's conversion of propylene and selectivity for 4MP1, as well as the strength of the catalyst support, the present invention provides an alkali metal catalyst.

[0007] In a first aspect, the present invention provides an alkali metal catalyst, wherein the support of the alkali metal catalyst contains an alkali metal salt and a silicate, and the total pore volume is not less than 0.2 mL / g.

[0008] In one or more optional embodiments, the support for the alkali metal catalyst preferably has a total pore volume of not less than 0.25 mL / g.

[0009] In one or more optional embodiments, the silicate is at least one silicate of a first group and / or a second group element, preferably sodium silicate and potassium silicate, more preferably sodium silicate.

[0010] In one or more optional embodiments, the alkali metal salt is at least one of an alkali metal carbonate or an alkali metal bicarbonate, preferably at least one of potassium carbonate, sodium carbonate, potassium bicarbonate or sodium bicarbonate, more preferably potassium carbonate and sodium carbonate, and even more preferably potassium carbonate.

[0011] Secondly, the present invention provides a method for preparing the above-mentioned alkali metal catalyst, wherein the method first prepares a support for the alkali metal catalyst, and the method for preparing the support for the alkali metal catalyst includes:

[0012] After mixing the alkali metal salt with the crown ether solution, graphite and silicate were added and then calcined.

[0013] In one or more optional embodiments, the mass ratio of the crown ether to the alkali metal salt is 0.01 to 20%.

[0014] In one or more optional embodiments, the mass ratio of graphite to the alkali metal salt is 0.2 to 1.5%.

[0015] In one or more optional embodiments, the mass ratio of the silicate to the alkali metal salt is 0.01 to 10%, preferably 0.1 to 5%, and more preferably 1 to 3%.

[0016] In one or more optional embodiments, water is used as a mixed solvent in the method for preparing the alkali metal catalyst support, wherein the mass ratio of water to the alkali metal carbonate is 0.23 to 0.32.

[0017] In one or more optional embodiments, the mixing temperature of the crown ether solution and the alkali metal salt is 0–200°C, and the mixing time is 0.1–3 h.

[0018] In one or more optional embodiments, the crown ether is 18-crown ether-6, dibenzo-18-crown-6 ether, aza-18-crown ether-6, benzo-12-crown-4, benzo-15-crown ether-5, benzo-18-crown-6-ether, 4-hydrochloroaminodibenzo-18-crown(ether)-6, 12-crown-4-ether, 15-crown ether-5, crown-8-ene, 4'-nitrobenzo-15-crown-5-ether, 4'-aminobenzo-15-crown-5-ether, N-phenylaza-15-crown-5-ether, 4'-carboxybenzo-15-crown-5-ether, 2-(hydroxymethyl)-12-crown-4-ether, 24-crown-8-ether, 15-crown-4[4-(2 [4-Dinitrophenylazo]phenol, 4'-acetylbenzo-18-crown-6-ether, 4'-acetylbenzo-15-crown-5-ether, 4'-formylbenzo-18-crown-6-ether, 1-aza-12-crown-4-ether, dibenzo-30-crown-10-ether, N,N'-dibenzyl-4,13-diaza-18-crown-6-ether, 4'-methoxycarbonylbenzo-15-crown-5-ether, 4'-nitrobenzo-18-crown-6-ether, dicyclohexano-18-crown-6-ether, 2-(allyloxymethyl)-18-crown-6-ether, 4'-bromobenzo-15-crown-5-ether, 2-(hydroxymethyl)-18-crown-6-ether, 4'-formylbenzo- 15-crown-5-ether, 1-aza-15-crown-5-ether, 18-crown-5[4-(2,4-dinitrophenylazo)phenol], dibenzo-15-crown-5-ether, dibenzo-21-crown-7-ether, bis(1,4-phenylene)-34-crown-10-ether, 4,13-diaza-18-crown-6-ether, dibenzo-24-crown-8-ether, 2-(hydroxymethyl)-15-crown-5-ether, 4-bromobenzo-18-crown-6-ether, 4,10-diaza-12-crown-4-ether, 1,3-diisopropoxycalixarene crown ether-6, 2-aminomethyl-18-crown-6, 4-tert-butylphenyl-15-crown-5, 4-vinylbenzyl-18 -crown ether-6, 2-aminomethyl-15-crown-5, cyclohexane-18-crown-6, 4-tert-butylcyclohexane-15-crown-5, poly(dibenzo-18-crown-6), 2,3-naphtho-15-crown ether-5, dicyclohexano-24-crown ether-8, 4'-amino-5'-nitrobenzo-15-crown-5 and 4',4""5")-ditert-butyldicyclohexano-18-crown-6; preferably, the crown ether is at least one of 18-crown ether-6, 15-crown ether-5, benzo-18-crown-6-ether, aza-18-crown ether-6, 4-tert-butylcyclohexane-15-crown-5 and dibenzo-24-crown-8-ether.

[0019] In one or more optional embodiments, the solvent of the crown ether solution is at least one of alcohols, ketones, ethers, esters, amines, aromatics, and chloroalkanes; preferably at least one of ethanol, isopropanol, acetone, and diethyl ether.

[0020] In one or more optional embodiments, the calcination temperature is 250–500°C and the calcination time is 2–5 hours.

[0021] In one or more alternative embodiments, the method further includes the step of loading sodium and / or potassium metal onto the prepared alkali metal catalyst support.

[0022] In one or more optional embodiments, the mass ratio of the sodium and / or potassium metal to the alkali metal catalyst support is 0.5 to 20%.

[0023] In one or more alternative embodiments, the loading method is molten loading.

[0024] In one or more optional embodiments, the temperature of the molten load is 10 to 240°C above the melting point of sodium and / or potassium, preferably 20 to 200°C above the melting point of sodium and / or potassium, and more preferably 30 to 100°C above the melting point of sodium and / or potassium.

[0025] Thirdly, the present invention also provides the application of the above-mentioned alkali metal catalyst in the dimerization of propylene to 4-methyl-1-pentene.

[0026] This invention improves the strength of the catalyst support by adding silicates to alkali metal salts, reduces catalyst breakage, and thus extends the catalyst's lifespan, making it suitable for high-pressure reactions.

[0027] This invention involves adding crown ethers with vacancy structures to alkali metal salts, uniformly mixing and complexing them, and then drying and calcining them to form a support with a special vacancy structure and uniform dispersion. After that, alkali metals are loaded onto the support, and the alkali metals fully combine with the lattice defects on the support surface to achieve equilibrium size and uniform dispersion. The resulting catalyst has both high propylene conversion and high 4MP1 selectivity. Detailed Implementation

[0028] The following provides a detailed description of the embodiments of the present invention: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Process parameters not specified in the following embodiments are generally performed under conventional conditions.

[0029] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0030] Unless otherwise specified, the term "alkali metal catalyst" in this application refers to the overall structure after the alkali metal is loaded onto the support, that is, the state in which the alkali metal is loaded onto the support and can be used for industrial applications.

[0031] The inventors implemented related technical solutions with reference to patent documents US4876410A, US4595787A, US4835330A, US5112791A, and US4727213A, and found that the propylene conversion rate and catalyst support strength were not ideal. After further research and development, the inventors obtained this invention, which achieves ideal propylene conversion rate and support strength.

[0032] In this embodiment of the invention, the carrier molding method is selected from extrusion molding, tablet molding, spherical molding and rotational molding, with extrusion molding being preferred; the shape can be cylindrical, clover, four-leaf clover, spherical, tablet or other granular shape; the extrusion diameter can be 1 to 5 mm.

[0033] In the embodiments of the present invention, the total pore volume of the support prepared is not less than 0.2 mL / g, and preferably the total pore volume is not less than 0.25 mL / g, for the preparation of alkali metal catalysts.

[0034] In this embodiment of the invention, the rotation speed of the low-speed stirring is 40-50 r / min; the speed of the low-speed vibration is 40-50 r / min.

[0035] The catalyst evaluation process in this embodiment of the invention includes:

[0036] Batch reactor:

[0037] Under a nitrogen atmosphere, the catalyst was added to a 250 mL autoclave. The mass of the autoclave was measured as m1. Then, propylene was injected into the autoclave, and the mass of the autoclave was measured as m2. The amount of propylene added was calculated as m. 丙 Subsequently, the reactor was heated to the reaction temperature and reacted for a certain period of time. The reaction system was then cooled to below 20°C, and the remaining gaseous components in the reactor were sampled and vented. The mass of the reactor after venting was measured as m³, and the mass of the liquid recovered was calculated as m. 液 Gas and liquid samples were collected for product component content analysis. Propylene conversion and 4MP1 selectivity were calculated.

[0038] (1) Propylene conversion rate C:

[0039]

[0040] (2) 4MP1 selectivity S:

[0041]

[0042] in:

[0043] m 丙 —The mass of propylene added before the reaction;

[0044] m 液 —Mass of the liquid recovered after the reaction;

[0045] X 液丙 —Percentage of propylene in liquid gas chromatography;

[0046] X 气丙 —Percentage of propylene in gas chromatography;

[0047] X 4MP1 — Percentage of 4MPa in liquid gas chromatography.

[0048] Fixed-bed gas-phase reaction:

[0049] Under nitrogen protection, approximately 50 mL of catalyst was loaded into the isothermal zone of the fixed-bed reactor, with the top and bottom supported by quartz sand. Polymer-grade propylene was pumped into the reaction apparatus via a horizontal flow pump, passing through a vaporizer into the reactor. The reaction temperature inside the vaporizer and reactor was maintained at 140–160 °C, with the pressure controlled at approximately 10 MPa and a controlled space velocity. The reaction products were analyzed by online chromatography via a back pressure device and a six-way valve. The propylene conversion and 4MPa selectivity were calculated.

[0050] The reaction results were analyzed by online chromatography. Propylene conversion and 4MP1 selectivity were calculated.

[0051] (1) Propylene conversion rate C:

[0052] C = (1-X) 丙 )×100%

[0053] (2) 4MP1 selectivity S:

[0054]

[0055] in:

[0056] X 丙 —Percentage of propylene in the gas chromatography of the product;

[0057] X 4MP1 — Percentage of 4MPa in the gas chromatogram of the product.

[0058] The following provides a detailed description of various specific embodiments of the alkali metal catalysts provided in the examples of this invention.

[0059] Example 1

[0060] Preparation of alkali metal catalyst supports:

[0061] Anhydrous potassium carbonate was ground using a grinder and sieved using 100-mesh, 150-mesh, 200-mesh, 250-mesh, 300-mesh, and 350-mesh sieves to obtain anhydrous potassium carbonate powders of <100 mesh, 100-150 mesh, 150-200 mesh, 200-250 mesh, 250-300 mesh, and 300-350 mesh grades, respectively.

[0062] Weigh 100g of anhydrous potassium carbonate powder (150-300 mesh). Dissolve 2g of aza-18-crown ether-6 in 5.0g of ethanol, add it to the anhydrous potassium carbonate powder, and stir at low speed for 1 hour at room temperature. Add 1.0g of graphite. Dissolve 0.5g of sodium silicate in 24g of deionized water, add it to the anhydrous potassium carbonate powder, and grind and mix until a uniform wet block mixture is formed.

[0063] The mixture was extruded using an extruder, producing cylindrical extrudates with a diameter of 1.5 mm. The extrudates were left to air dry overnight, then dried in a forced-air drying oven at 80°C for 6 hours, followed by calcination in a muffle furnace at 300°C for 4 hours to form an alkali metal catalyst support, which was then sealed and stored. The strength of this alkali metal catalyst support was measured, and the strength was 138 N / cm. The experimental data are shown in Table 1.

[0064] Example 2

[0065] Preparation of alkali metal catalyst supports:

[0066] Weigh 100g of anhydrous potassium carbonate powder (200-350 mesh) obtained from the sieve in Example 1. Dissolve 3.5g of 18-crown ether-6 in 5.0g of isopropanol, add it to the anhydrous potassium carbonate powder, and stir at low speed for 1 hour at 100°C. Cool to room temperature. Add 1.0g of graphite. Dissolve 5g of anhydrous potassium silicate in 28g of deionized water, add it to the anhydrous potassium carbonate powder, and grind it to form a uniform wet block mixture.

[0067] The mixture was extruded using an extruder, producing cylindrical extrudates with a diameter of 3.0 mm. The extrudates were left to air dry overnight, then dried in a vacuum drying oven at 100°C for 4 hours, followed by calcination in a muffle furnace at 320°C for 5 hours to form an alkali metal catalyst support, which was then sealed and stored. The strength of this alkali metal catalyst support was measured, and the strength was 211 N / cm. The experimental data are shown in Table 1.

[0068] Example 3

[0069] Preparation of alkali metal catalyst supports:

[0070] Weigh out 10g of 150-200 mesh anhydrous potassium carbonate powder, 70g of 200-250 mesh anhydrous potassium carbonate powder, and 20g of 250-350 mesh anhydrous potassium carbonate powder obtained from the sieving in Example 1, totaling 100g. Dissolve 5g of 15-crown ether-5 in 5.0g of ethanol and add it to the anhydrous potassium carbonate powder. Stir at low speed for 1 hour at room temperature. Add 1.5g of graphite. Dissolve 1.0g of anhydrous sodium silicate in 10g of deionized water and add it to the anhydrous potassium carbonate powder. While grinding and mixing, continue to add 20g of deionized water until a uniform wet block is formed and placed in the mixture.

[0071] The mixture was extruded using an extruder to produce four-leaf clover-shaped extrudates with a diameter of 4.0 mm. The extrudates were dried overnight at 30°C in a forced-air drying oven, then dried again at 150°C for 5 hours, and finally calcined in a muffle furnace at 420°C for 2.5 hours to form an alkali metal catalyst support, which was then sealed and stored. The strength of this alkali metal catalyst support was measured to be 182 N / cm, and the experimental data are shown in Table 1.

[0072] Example 4

[0073] Preparation of alkali metal catalyst supports:

[0074] Weigh 100g of anhydrous potassium carbonate powder (200-250 mesh) obtained from the sieve in Example 1. Dissolve 3g of 18-crown ether-6 in 5.0g of ethanol and add it to the anhydrous potassium carbonate powder. Stir at low speed for 1 hour at 60°C. Add 1.0g of graphite. Dissolve 2.0g of anhydrous sodium silicate and 1g of magnesium silicate in 28g of deionized water and add them to the anhydrous potassium carbonate powder. Grind and mix to form a uniform wet block mixture.

[0075] The mixture was extruded using an extruder, producing cylindrical extrudates with a diameter of 1.0 mm. The extrudates were allowed to air dry overnight, then dried in a forced-air drying oven at 120°C for 5 hours, followed by calcination in a muffle furnace at 260°C for 6 hours to form an alkali metal catalyst support, which was then sealed and stored. The strength of this alkali metal catalyst support was measured to be 154 N / cm, and the experimental data are shown in Table 1.

[0076] Example 5

[0077] Preparation of alkali metal catalyst supports:

[0078] Weigh 100g of anhydrous potassium carbonate powder (150-250 mesh) obtained from the sieve in Example 1. Dissolve 1g of 18-crown ether-6 in 3.0g of ethanol and add it to the anhydrous potassium carbonate powder. Stir at low speed for 3 hours at room temperature. Add 1.0g of graphite. Dissolve 10.0g of anhydrous sodium silicate in 32g of deionized water and add it to the anhydrous potassium carbonate powder. Grind and mix the mixture until a uniform wet block mixture is formed.

[0079] The mixture was extruded using an extruder, producing clover-shaped extrudates with a diameter of 2.5 mm. The extrudates were dried overnight at 30°C in a forced-air drying oven, then dried for 6 hours at 80°C in the same oven, and finally calcined in a muffle furnace at 450°C for 2.5 hours to form an alkali metal catalyst support, which was then sealed and stored. The strength of this alkali metal catalyst support was measured to be 206 N / cm, and the experimental data are shown in Table 1.

[0080] Example 6

[0081] Preparation of alkali metal catalyst supports:

[0082] Weigh 100g of anhydrous potassium carbonate powder (150-350 mesh) obtained from the sieve in Example 1. Dissolve 2.5g of 18-crown ether-6 in 4.0g of ethanol and add it to the anhydrous potassium carbonate powder. Stir at low speed for 3 hours at room temperature. Add 1.0g of graphite. Dissolve 3.0g of anhydrous sodium silicate in 29g of deionized water and add it to the anhydrous potassium carbonate powder. Grind and mix the mixture until a uniform wet block mixture is formed.

[0083] The mixture was extruded using an extruder, producing cylindrical extrudates with a diameter of 2.0 mm. The extrudates were left to air dry overnight, then dried in a forced-air drying oven at 100°C for 6 hours, followed by calcination in a muffle furnace at 400°C for 3 hours to form an alkali metal catalyst support, which was then sealed and stored. The strength of this alkali metal catalyst support was measured to be 195 N / cm, and the experimental data are shown in Table 1.

[0084] Preparation of alkali metal catalysts:

[0085] In an anhydrous and oxygen-free chamber, 70g of the alkali metal catalyst support prepared above was weighed and added to a 200mL pressure bath. 3.0g of potassium and 0.5g of sodium were weighed and added to the pressure bath, and the mixture was sealed. The pressure bath was placed in a homogeneous reactor, heated to 120℃, and rotated for 6 hours. The resulting alkali metal catalyst was silver-purple and was sealed and stored for later use.

[0086] Catalyst evaluation:

[0087] 10g of the prepared alkali metal catalyst was weighed and added to a 250mL high-pressure reactor. Then, 83g of propylene was injected into the reactor. The material in the reactor was heated to 150℃ and reacted for 10h. After the reaction, the system was cooled to below 20℃, the gas phase was vented, and a sample was taken for gas chromatography analysis. 34g of the liquid phase was collected and analyzed by gas chromatography. The calculated propylene conversion rate was 40.5%, and the 4MPa selectivity was 85.1%. No fragmentation was observed in the alkali metal catalyst.

[0088] Example 7

[0089] Preparation of alkali metal catalyst supports:

[0090] Weigh 100g of anhydrous potassium carbonate powder (150-300 mesh) obtained from the sieve in Example 1. Dissolve 3g of 18-crown ether-6 in 5.0g of ethanol and add it to the anhydrous potassium carbonate powder. Stir at low speed for 1 hour at 60°C. Add 1.0g of graphite. Dissolve 6g of magnesium silicate in 26g of deionized water and add it to the anhydrous potassium carbonate powder. Grind and mix the mixture until a uniform wet block mixture is formed.

[0091] The mixture was extruded using an extruder, producing cylindrical extrudates with a diameter of 1.5 mm. The extrudates were allowed to air dry overnight, then dried in a forced-air drying oven at 60°C for 7 hours, followed by calcination in a muffle furnace at 350°C for 4 hours to form an alkali metal catalyst support, which was then sealed and stored. The strength of this alkali metal catalyst support was measured, and the strength was 171 N / cm. The experimental data are shown in Table 1.

[0092] Preparation of alkali metal catalysts:

[0093] Weigh 80g of the alkali metal catalyst support prepared above and add it to a 500mL three-necked flask. Heat it to 160℃ under a nitrogen flow and add 4g of potassium under nitrogen protection. Adjust the stirring speed to a low nitrogen flow for 2.5h and then cool it to below 50℃. The resulting alkali metal catalyst is silvery-gray. Add 100mL of dehydrated cyclohexane and seal it for later use.

[0094] Catalyst evaluation:

[0095] 11g of the prepared alkali metal catalyst was weighed and added to a 250mL high-pressure reactor. Then, 85g of propylene was injected into the reactor. The material in the reactor was heated to 150℃ and reacted for 10h. After the reaction, the system was cooled to below 20℃, the gas phase was vented, and a sample was taken for gas chromatography analysis. 31g of the liquid phase was collected and analyzed by gas chromatography. The calculated propylene conversion rate was 36.4%, and the 4MPa selectivity was 86.6%. No fragmentation of the alkali metal catalyst was observed.

[0096] Example 8

[0097] Preparation of alkali metal catalyst supports:

[0098] Weigh 100g of anhydrous potassium carbonate powder (200-350 mesh) obtained from the sieve in Example 1. Dissolve 2.5g of 18-crown ether-6 in 2.0g of ethanol and add it to the anhydrous potassium carbonate powder. Stir at low speed for 0.5h at 60°C and cool to room temperature. Add 1.0g of graphite. Dissolve 2.5g of anhydrous sodium silicate in 10g of deionized water and add it to the anhydrous potassium carbonate powder. While grinding (or kneading), continue to add 17g of deionized water until a uniform wet block mixture is formed.

[0099] The mixture was extruded using an extruder, producing clover-shaped extrudates with a diameter of 3.5 mm. The extrudates were left to air dry overnight, then dried in a forced-air drying oven at 80°C for 8 hours, followed by calcination in a muffle furnace at 380°C for 4 hours to form an alkali metal catalyst support, which was then sealed and stored. The strength of this alkali metal catalyst support was measured to be 202 N / cm, and the experimental data are shown in Table 1.

[0100] Preparation of alkali metal catalysts:

[0101] In an anhydrous and oxygen-free chamber, 80g of the alkali metal catalyst support prepared above was added to a 200mL pressure bath, and 4g of potassium was weighed and added to the pressure bath. The mixture was then sealed. The pressure bath was placed in a homogeneous reactor, heated to 150℃, and rotated for 5 hours. The resulting alkali metal catalyst was silver-purple and was sealed and stored for later use.

[0102] Catalyst evaluation:

[0103] 10.2 g of the alkali metal catalyst prepared above was weighed and added to a 250 mL high-pressure reactor. Then, 80 g of propylene was injected into the reactor. The material in the reactor was heated to 150 °C and reacted for 10 h. After the reaction was completed, the system was cooled to below 20 °C, the gas phase was vented, and a sample was taken for gas chromatography analysis. 23 g of the liquid phase was collected and analyzed by gas chromatography. The propylene conversion rate was calculated to be 28.3%, and the 4MPa selectivity was 87.9%. The alkali metal catalyst did not exhibit any breakage.

[0104] Comparative Example 1

[0105] Preparation of alkali metal catalyst supports:

[0106] Weigh 100g of anhydrous potassium carbonate powder (150-350 mesh) obtained from the sieving process in Example 1. Add 1.0g of graphite and 29g of deionized water, and grind and mix to form a uniform wet block mixture.

[0107] The mixture was extruded using an extruder, producing cylindrical extrudates with a diameter of 2.0 mm. The extrudates were left to air dry overnight, then dried in a forced-air drying oven at 100°C for 6 hours, followed by calcination in a muffle furnace at 400°C for 3 hours to form an alkali metal catalyst support, which was then sealed and stored. The strength of this alkali metal catalyst support was measured to be 118 N / cm, and the experimental data are shown in Table 1.

[0108] Preparation of alkali metal catalysts:

[0109] In an anhydrous and oxygen-free chamber, 70g of the above-prepared carrier was added to a 200mL pressure bath. 3.0g of potassium and 0.5g of sodium were weighed and added to the pressure bath, and the chamber was sealed. The pressure bath was placed in a homogeneous reactor, heated to 120℃, and rotated for 6 hours. The resulting alkali metal catalyst was silver-purple and sealed for later use.

[0110] Catalyst evaluation:

[0111] 10g of the prepared alkali metal catalyst was weighed and added to a 250mL high-pressure reactor. Then, 81g of propylene was injected into the reactor. The material in the reactor was heated to 150℃ and reacted for 10h. After the reaction, the system was cooled to below 20℃, the gas phase was vented, and a sample was taken for gas chromatography analysis. 12g of the liquid phase was collected and analyzed by gas chromatography. The propylene conversion rate was calculated to be 14.8%, and the 4MPa selectivity was 85.5%. A small amount of fragmentation was observed in the alkali metal catalyst.

[0112] Comparative Example 2

[0113] Preparation of alkali metal catalyst supports:

[0114] Weigh 100g of anhydrous potassium carbonate powder (250-350 mesh) obtained from the sieving process in Example 1. Add 1.0g of graphite and 27g of deionized water, and grind and mix to form a uniform wet block mixture.

[0115] The mixture was extruded using an extruder, producing clover-shaped extrudates with a diameter of 3.5 mm. The extrudates were left to air dry overnight, then dried in a forced-air drying oven at 80°C for 6 hours, followed by calcination in a muffle furnace at 380°C for 4 hours to form an alkali metal catalyst support, which was then sealed and stored. The strength of this alkali metal catalyst support was measured to be 97 N / cm, and the experimental data are shown in Table 1.

[0116] Table 1. Experimental data of alkali metal catalyst supports prepared in Examples 1-8 and Comparative Examples 1-2.

[0117]

[0118]

[0119] The alkali metal catalyst support prepared by the method of this invention was found by electron microscopy to be an aggregate of spherical particles, with the most probable primary particle size <1 μm. Characterization by mercury porosimetry showed a pore size distribution range of 80–10000 nm and a total pore volume of not less than 0.2 mL / g. Comparison of experimental data in Table 1 shows that adding crown ethers and silicates during support treatment results in a catalyst with higher support strength, reaching over 130 N / cm and even over 200 N / cm, compared to the catalyst prepared without crown ether and silicate treatment. This reduces catalyst breakage and thus improves catalyst lifespan.

[0120] Although specific embodiments of the invention have been described in detail, those skilled in the art will understand that various modifications and substitutions can be made to those details based on all the teachings disclosed, and all such changes are within the scope of protection of this invention. The full scope of this invention is given by the appended claims and any equivalents thereof.

Claims

1. An alkali metal catalyst for the dimerization of propylene to 4-methyl-1-pentene, characterized in that, The support for the alkali metal catalyst contains alkali metal salts and silicates, with a total pore volume of not less than 0.2 mL / g; The alkali metal salt is at least one of alkali metal carbonate or alkali metal bicarbonate; the silicate is at least one of silicates of Group 1 and / or Group 2 elements. The preparation method of the support for the alkali metal catalyst includes: mixing an alkali metal salt with a crown ether solution, then adding graphite and silicate, and calcining; the calcination temperature is 250~500℃, and the calcination time is 2~5h; the mass ratio of silicate to alkali metal salt is 0.01~10%. The method for preparing the alkali metal catalyst includes the step of loading sodium metal and / or potassium metal onto a support for the alkali metal catalyst.

2. The alkali metal catalyst according to claim 1, characterized in that, The total pore volume of the support for the alkali metal catalyst is not less than 0.25 mL / g.

3. The alkali metal catalyst according to claim 1, characterized in that, The silicates are sodium silicate and potassium silicate.

4. The alkali metal catalyst according to claim 3, characterized in that, The silicate is sodium silicate.

5. The alkali metal catalyst according to claim 1, characterized in that, The alkali metal salt is at least one of potassium carbonate, sodium carbonate, potassium bicarbonate, or sodium bicarbonate.

6. The alkali metal catalyst according to claim 5, characterized in that, The alkali metal salt is at least one of potassium carbonate and sodium carbonate.

7. The alkali metal catalyst according to claim 6, characterized in that, The alkali metal salt is potassium carbonate.

8. The alkali metal catalyst according to claim 1, characterized in that, In the method for preparing the support for the alkali metal catalyst, the mass ratio of the crown ether to the alkali metal salt is 0.01~20%.

9. The alkali metal catalyst according to claim 1, characterized in that, In the preparation method of the support for the alkali metal catalyst, the mass ratio of graphite to the alkali metal salt is 0.2~1.5%.

10. The alkali metal catalyst according to claim 1, characterized in that, In the preparation method of the support for the alkali metal catalyst, the mass ratio of the silicate to the alkali metal salt is 0.01~10%.

11. The alkali metal catalyst according to claim 10, characterized in that, In the preparation method of the support for the alkali metal catalyst, the mass ratio of the silicate to the alkali metal salt is 0.1~5%.

12. The alkali metal catalyst according to claim 11, characterized in that, In the preparation method of the support for the alkali metal catalyst, the mass ratio of the silicate to the alkali metal salt is 1~3%.

13. The alkali metal catalyst according to claim 1, characterized in that, In the preparation method of the alkali metal catalyst support, water is used as a mixed solvent, and the mass ratio of water to alkali metal carbonate is 0.23~0.

32.

14. The alkali metal catalyst according to claim 1, characterized in that, In the preparation method of the support for the alkali metal catalyst, the mixing temperature of the crown ether solution and the alkali metal salt is 0~200℃, and the mixing time is 0.1~3h.

15. The alkali metal catalyst according to claim 1, characterized in that, The crown ether is 18-crown ether-6, dibenzo-18-crown-6 ether, aza-18-crown ether-6, benzo-12-crown-4, benzo-15-crown ether-5, benzo-18-crown-6-ether, 4-hydrochloroaminodibenzo-18-crown(ether)-6, 12-crown-4-ether, 15-crown ether-5, crown-8-ene, 4'-nitrobenzo-15-crown-5-ether, 4'-aminobenzo-15-crown-5-ether, N-benzaza-15-crown-5-ether, 4'-carboxybenzo-15-crown-5-ether, 2-(hydroxymethyl)-12-crown-4-ether, 24-crown-8-ether, 1 5-crown-4[4-(2,4-dinitrophenylazo)phenol], 4'-acetylbenzo-18-crown-6-ether, 4'-acetylbenzo-15-crown-5-ether, 4'-formylbenzo-18-crown-6-ether, 1-aza-12-crown-4-ether, dibenzo-30-crown-10-ether, N,N'-dibenzyl-4,13-diaza-18-crown-6-ether, 4'-methoxycarbonylbenzo-15-crown-5-ether, 4'-nitrobenzo-18-crown-6-ether, dicyclohexano-18-crown-6-ether, 2-(allyloxymethyl)-18-crown-6-ether, 4'-bromobenzo- 15-crown-5-ether, 2-(hydroxymethyl)-18-crown-6-ether, 4'-formylbenzo-15-crown-5-ether, 1-aza-15-crown-5-ether, 18-crown-5[4-(2,4-dinitrophenylazo)phenol], dibenzo-15-crown-5-ether, dibenzo-21-crown-7-ether, bis(1,4-phenylene)-34-crown-10-ether, 4,13-aza-18-crown-6-ether, dibenzo-24-crown-8-ether, 2-(hydroxymethyl)-15-crown-5-ether, 4-bromobenzo-18-crown-6-ether, 4,10-aza-12-crown At least one of 4-ether, 1,3-diisopropoxycalixarene crown ether-6, 2-aminomethyl-18-crown-6, 4-tert-butylphenyl-15-crown-5, 4-vinylbenzyl-18-crown ether-6, 2-aminomethyl-15-crown-5, cyclohexane-18-crown-6, 4-tert-butylcyclohexane-15-crown-5, poly(dibenzo-18-crown-6), 2,3-naphtho-15-crown ether-5, dicyclohexano-24-crown ether-8, 4'-amino-5'-nitrobenzo-15-crown-5 and 4',4''(5'')-ditert-butyldicyclohexyl-18-crown-6.

16. The alkali metal catalyst according to claim 15, characterized in that, The crown ether is at least one selected from 18-crown ether-6, 15-crown ether-5, benzo-18-crown-6-ether, aza-18-crown ether-6, 4-tert-butylcyclohexane-15-crown-5, and dibenzo-24-crown-8-ether.

17. The alkali metal catalyst according to claim 1, characterized in that, The solvent of the crown ether solution is at least one of alcohols, ketones, ethers, esters, amines, aromatics, and chloroalkanes.

18. The alkali metal catalyst according to claim 17, characterized in that, The solvent for the crown ether solution is at least one of ethanol, isopropanol, acetone, and diethyl ether.

19. The alkali metal catalyst according to claim 1, characterized in that, The mass ratio of sodium and / or potassium to the support of the alkali metal catalyst is 0.5-20%.

20. The alkali metal catalyst according to claim 1, characterized in that, The loading method is molten loading.

21. The alkali metal catalyst according to claim 20, characterized in that, The temperature of the molten load is 10~240℃ higher than the melting point of sodium and / or potassium.

22. The alkali metal catalyst according to claim 21, characterized in that, The temperature of the molten load is 20~200℃ higher than the melting point of sodium and / or potassium.

23. The alkali metal catalyst according to claim 22, characterized in that, The temperature of the molten load is 30~100℃ higher than the melting point of sodium and / or potassium.

24. The use of the alkali metal catalyst according to any one of claims 1 to 23 in the dimerization of propylene to 4-methyl-1-pentene.

Images