CN114425335B

CN114425335B - Bimetallic catalyst for synthesizing polyether amine and preparation method and application thereof

Info

Publication number: CN114425335B
Application number: CN202010973088.0A
Authority: CN
Inventors: 赵亮
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2020-09-16
Filing date: 2020-09-16
Publication date: 2023-07-04
Anticipated expiration: 2040-09-16
Also published as: CN114425335A

Abstract

The invention relates to a bimetallic catalyst for synthesizing polyether amine, a preparation method and application thereof. The catalyst comprises a carrier, a first metal and a second metal, wherein the first metal is at least one element selected from lanthanum, cerium and yttrium, and the second metal is at least one element selected from silver, tin and indium; the first metal content is 0.75-5.0 wt% and the second metal content is 0.006-0.1 wt% based on the mass of the catalyst. The catalyst is used in polyether amine synthesis reaction, and can obviously improve the activity, selectivity and stability of the catalyst.

Description

Bimetallic catalyst for synthesizing polyether amine and preparation method and application thereof

Technical Field

The invention relates to a catalyst for synthesizing polyether amine and a preparation method thereof, in particular to a bimetallic catalyst for synthesizing polyether amine and a preparation method thereof, and application thereof in synthesizing polyether amine.

Background

Polyetheramines are a class of polyolefin compounds having a soft polyether backbone, terminated with primary or secondary amine groups. The structure of which contains at least one polyalkylene glycol functional group, which is critical to its properties. Polyalkylene glycols can increase the water solubility of polyetheramines and also affect the melting point and viscosity of polyetheramines. The hydrocarbon groups connected with the terminal amino groups can be classified into aromatic groups and aliphatic groups according to the different structures. The polyetheramine is light yellow or colorless transparent liquid at room temperature, has the advantages of low viscosity, low vapor pressure, high primary amine content and the like, and can be dissolved in solvents such as ethanol, aliphatic or aromatic hydrocarbons, ketones, water and the like. Since the industrialized production of the 60 s of the 20 th century, intensive research has been conducted on the synthesis method and application mode thereof. Due to the good reactivity of the terminal amino group, the polyether amine can act with various reactive groups, and the application field of the polyether amine is increasingly wide. In polyether amine synthesis systems, catalysts have been one of the hot spots and emphasis in research and development. At present, the catalyst for synthesizing polyether amine mainly comprises three types of Raney type, load type and crystal type. The reactivity, primary amine selectivity and service life of the catalyst are directly related to the quality of the polyether amine product, the cost price and the like.

CN107915836a discloses a polyetheramine and a process for preparing the same. The preparation method comprises the steps of using a skeletal nickel catalyst and a magnesium aluminum composite oxide as a composite catalyst; polyether, amine compounds and hydrogen are added for ammoniation reaction; after gas-liquid separation of the reaction product, dehydrating and deaminizing the liquid material, mixing the liquid material with an amine compound and hydrogen, and carrying out ammoniation reaction again; the reaction product is cooled, and after gas-liquid separation, the liquid material is dehydrated and deaminated, so that the skeletal nickel catalyst is the Raney catalyst, which has strong reaction activity, but is not easy to control stably and has low selectivity, and excessive reaction and carbon deposit deactivation are easy to cause. The magnesium-aluminum composite oxide has a certain auxiliary catalytic effect as a cocatalyst, but is only mechanically mixed with the skeletal nickel catalyst and does not have organic combination, so the auxiliary catalytic effect is limited.

CN107876098A discloses a catalyst for synthesizing polyetheramine, a preparation method and application thereof. The supported catalyst comprises an active carbon carrier and a metal oxide supported on the carrier, wherein the active carbon carrier loaded with the metal oxide also contains an amide nitrogen group for carrying out surface modification on the active carbon carrier. The catalyst prepared by the method has a certain hydrophobic effect, and the problem of catalyst deactivation is relieved to a certain extent. However, the pore size range of the activated carbon carrier is larger than 100nm, and compared with a low molecular weight polyetheramine product, the activated carbon carrier is too wide and is not beneficial to the exertion of pore canal restriction limiting effect, namely the selectivity of the prepared catalyst on primary amine products is limited. In addition, in the process of loading metal ions, the common active carbon carrier only introduces the metal ions into the inside and the outside of the carrier pore channels, but embeds the metal ions in a lattice matching (lattice matching) mode, namely the loaded metal ions can run off along with the service period, so that the service life of the catalyst is reduced. The amide nitrogen groups on the surface of the carrier can improve the hydrophobic stability of the carrier, but simultaneously passivate active sites on the surface of the carrier, so that the catalytic reaction activity of the carrier is weakened.

CN108014821a discloses a catalyst for synthesizing polyetheramines comprising NbAlO ₄ Carrier and NiO and Au loaded on carrier ₂ O ₃ And SeO ₂ An active component; wherein, the content of NiO as an active component in the catalyst is 1 to 15 weight percent and Au is calculated according to the total weight of the catalyst ₂ O ₃ The content of (B) is 0.01-2 wt%, seO ₂ The content of NbAlO is 0.01-1 wt% ₄ The support is prepared by a solid state reaction between a niobium-containing compound and alumina. Nb (Nb) ₂ O ₅ The introduction of (2) can partially inhibit the rehydration of alumina and improve the water-resistant stability of the catalyst. However, the generated NbAlO ₄ Attached to the surface of alumina, is easily detached from the alumina in the reaction stage, and causes a decrease in the reactivity of the catalyst. Furthermore, the noble metal Au in the active component is easy to generate adverse reactions such as oxidization, agglomeration and the like, and the catalytic activity of the noble metal Au is influenced.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a bimetallic catalyst for synthesizing polyetheramine, a preparation method thereof and application thereof in synthesizing polyetheramine. The catalyst provided by the invention is used in the reaction of synthesizing polyether amine, and can obviously improve the activity, selectivity and stability of the catalyst.

The first aspect of the invention provides a bimetallic catalyst for synthesizing polyetheramine, the catalyst comprises a carrier, a first metal and a second metal, wherein the first metal is selected from at least one element of lanthanum, cerium and yttrium, and the second metal is selected from at least one element of silver, tin and indium; the first metal content is 0.75-5.0 wt% and the second metal content is 0.006-0.1 wt% based on the mass of the catalyst.

Further, the first metal is preferably yttrium; the second metal is preferably silver.

Further, the carrier of the catalyst is a carbon carrier, and the carbon carrier is obtained by roasting corn silk and plumeria rubra in a combined way.

Further, the specific surface area of the catalyst is 820m ² /g～930m ² Per g, pore volume of 0.65cm ³ /g～0.84cm ³ And/g, the average pore diameter is 8 nm-10 nm, and the metal grain size is 1.4 nm-1.8 nm.

Further, the carbon carrier obtained in the step (1) in the preparation method has a phosphorus content of 8.5-10.7 wt%.

The second aspect of the invention provides a preparation method of a bimetallic catalyst for synthesizing polyetheramine, comprising the following steps:

(1) Dissolving a first metal salt in a carbon carrier aqueous solution containing a cyano compound, performing first mixing, and then adding a second metal salt, performing second mixing;

(2) Dropwise adding an aqueous solution of a reducing agent into the mixed solution obtained in the step (1), and carrying out third mixing;

(3) Filtering, washing and drying the mixture obtained in the step (2) to obtain the bimetallic catalyst for synthesizing polyether amine.

Further, the first metal salt in step (1) in the preparation method is at least one selected from lanthanum nitrate hexahydrate, cerium nitrate hexahydrate and yttrium nitrate hexahydrate, preferably yttrium nitrate hexahydrate. The second metal salt is at least one selected from silver nitrate, stannous chloride and indium nitrate, and preferably silver nitrate.

Further, the cyano compound in step (1) in the preparation method is at least one selected from acetonitrile, propionitrile and cyanamide, preferably cyanamide.

Further, in the preparation method, the first mixing in the step (1) adopts mechanical stirring, the stirring speed is generally 200 rpm-300 rpm, the stirring time is 20 min-40 min, and the stirring temperature is 20-30 ℃.

Further, in the preparation method, the mass ratio of the first metal salt, the cyano compound, the carbon carrier, the water and the second metal salt in the step (1) is 1: (300-600): (350-650): (10000-33000): (0.0015 to 0.0065), preferably 1: (400-500): (450-500): (18000-26000): (0.0028 to 0.0042).

Further, the carbon carrier in the step (1) in the preparation method is obtained by roasting corn silk and plumeria rubra in a combined manner.

The preparation method of the carbon carrier in the step (1) in the preparation method comprises the following steps: corn silk and plumeria rubra are mixed according to the mass ratio of corn silk to plumeria rubra of 1: (0.05-0.25), mixing and grinding, and mixing the ground material with an acid solution according to the mass ratio of 1: (0.3-1), and then drying and roasting to obtain the carbon carrier.

Further, the corn silk and the plumeria rubra are pretreated, the purpose of the pretreatment is to remove impurities on the surfaces of the corn silk and the plumeria rubra, a washing mode is generally adopted, for example, deionized water is used for washing the corn silk and the plumeria rubra, and after washing, drying is needed, the drying temperature is 40-70 ℃, and the drying time is 16-30 hours.

Further, the acid solution can be one or more of citric acid solution, oxalic acid solution and phosphoric acid solution, preferably phosphoric acid solution, and the mass concentration is 70-90 wt%.

Further, the ground material is mixed with an acid solution, and the drying conditions after mixing are as follows: the drying temperature is 50-70 ℃, the drying time is 1-5 h, and the roasting conditions are as follows: roasting for 2-4 h at 170-240 ℃ and 6-12 h at 350-500 ℃ under inert atmosphere.

Further, the specific preparation method of the carbon carrier in the step (1) in the preparation method is as follows:

placing the corn silk and the plumeria rubra washed by deionized water into a blast drying oven at 40-70 ℃ for drying for 16-30 h, and mixing the dried corn silk and plumeria rubra according to the mass ratio of 1: (0.05-0.25) and grinding to the fineness of 40-60 meshes. Mixing the ground material with phosphoric acid with the concentration of 70-90 wt% according to the mass ratio of 1: (0.3-1) and placing the mixture in a blast drying oven at 40-70 ℃ for soaking for 1-5 h. Taking out the immersed material, transferring the immersed material into a tube furnace, and introducing inert gas such as high-purity nitrogen, argon and the like at a flow rate of 60-100 mL/min; and heating to 170-240 ℃ at the speed of 3-8 ℃/min, staying for 2-4 h, heating to 350-500 ℃ at the speed of 1-5 ℃/min, and performing constant temperature treatment for 6-12 h. Naturally cooling the sample subjected to constant temperature treatment to room temperature, taking out, flushing with 0.07-0.15 mol/L hydrochloric acid, repeatedly flushing with deionized water to neutrality, and transferring to a blast drying oven at 40-70 ℃ for drying for 16-30 h to obtain the carbon carrier.

Further, in the preparation method, the second mixing in the step (1) adopts mechanical stirring, the stirring speed is generally 400-500 rpm, the stirring time is 60-120 min, and the stirring temperature is 20-30 ℃.

Further, the reducing agent in the step (2) in the preparation method is at least one selected from sodium borohydride, lithium aluminum hydride and potassium borohydride, and preferably lithium aluminum hydride.

Further, the amount of the aqueous solution of the reducing agent in the step (2) in the preparation method is (0.75-1.25) according to the mass ratio of the reducing agent to the water to the first metal salt: (150-350): 1, preferably (0.85 to 1.05): (200-300): 1. the titration time of the dropwise addition in the step (2) is 5-45 min, preferably 15-30 min.

Further, the third mixing in the step (2) adopts mechanical stirring, the general rotating speed is 400 rpm-500 rpm, the stirring time is 12 h-16 h, and the stirring temperature is 20-30 ℃.

Further, the drying in the step (3) in the preparation method is preferably drying in a vacuum drying oven, the vacuum degree is 120 Pa-150 Pa, the drying temperature is 60-80 ℃, and the drying time is 8-12 h.

The third aspect of the invention provides the application of the bimetallic catalyst for synthesizing polyether amine in synthesizing polyether amine by polyether polyol.

Further, the raw polyether polyol is preferably polypropylene glycol having an average molecular weight of less than 500.

Further, the mass ratio of the catalyst to the polypropylene glycol to the ammonia water is 1: (16-26): (14-24), wherein the mass concentration of ammonia water is 28-30wt%, and the reaction conditions for synthesizing polyether amine from polyether polyol are as follows: the reaction temperature is 140-170 ℃, the reaction pressure is 2.5-4.5 MPa, and the reaction time is 1.5-4.5 h.

Compared with the prior art, the invention has the following beneficial effects:

(1) The bimetallic catalyst for synthesizing polyetheramine provided by the invention is used in the reaction for synthesizing polyetheramine, and can obviously improve the activity, selectivity and stability of the catalyst.

(2) According to the catalyst disclosed by the invention, corn silk and plumeria rubra are combined and roasted to obtain the carbon carrier, on one hand, the plant carbon carrier material is wide in source, economical and environment-friendly, on the other hand, the corn silk is rich in cysteine components, plumeria rubra is rich in caffeoyl plumeria glycoside and dioxygen plumeria neo glucopyranoside components, on the other hand, lattice defects exist in the structure of the carbon carrier material obtained by combining and roasting the corn silk and plumeria rubra, the metal elements in the first metal salt are easy to induce to exist in the catalyst structure in the form of (111) crystal faces, and the metal element (111) crystal faces in the first metal salt are favorable for promoting the exertion of the selective dehydrogenation effect of the metal elements, so that the yield of primary amine products is improved; and the utilization efficiency of the metal element in the first metal salt in the (111) crystal face structure is highest, so that the consumption of the metal element is reduced, namely the catalyst cost is saved to a certain extent. In addition, a certain amount of hydroxyl, sulfhydryl and carboxyl groups exist in the structure of the carbon carrier material after combined roasting, and the groups are tightly combined with the metal salt component in a chemical reaction mode to prevent metal ions from falling off, and meanwhile, the groups also promote the carbon carrier to exist in a reduced state form, so that the oxidation of the supported metal elements is prevented, and the activity, the selectivity and the service life of the catalyst are improved.

(3) In the catalyst, due to the induction effect of the carbon carrier, the metal element in the first metal salt exists in the form of a (111) crystal face, the interface energy of the metal element in the first metal salt and the metal element in the second metal salt during the coupling reaction is minimum, ultra-small clusters are easy to form between the metal element and the metal element, the synergistic reaction effect is optimal, the reaction activities of dehydrogenation, hydrogenation and the like are high, and the selectivity is good.

(4) The cyano compound is added in the synthesis stage of the catalyst, and the cyano functional group provides additional electron pairs to coordinate with the metal crystal nucleus, so that the oxidation of metal crystals is effectively reduced, the infinite growth of the metal crystals is prevented, and the activity, the selectivity and the stability of the catalyst are improved.

(5) The catalyst of the invention is added with the reducing agent in the synthesis stage, and the metal ions are reduced to the zero-valence metal element in situ by means of the hydrogen released by the reducing agent, so that the reduction steps such as introducing hydrogen and the like in the hydrogenation catalytic amination reaction process are reduced, the production cost is saved, and the economic benefit is improved.

(6) The preparation method is simple in preparation process, convenient to operate, energy-saving, environment-friendly, free of special processing equipment and suitable for industrial production.

Drawings

FIG. 1 is a high resolution transmission electron micrograph of the catalyst prepared in example 1;

FIG. 2 is a high resolution transmission electron micrograph of the catalyst prepared in example 2;

FIG. 3 is a high resolution transmission electron micrograph of the catalyst prepared in example 5;

FIG. 4 is a high resolution transmission electron micrograph of the catalyst prepared in example 7;

FIG. 5 is a high resolution transmission electron micrograph of the catalyst prepared in comparative example 1;

FIG. 6 is a high resolution transmission electron micrograph of the catalyst prepared in comparative example 2.

Detailed Description

The following detailed description of embodiments of the invention is provided, but it should be noted that the scope of the invention is not limited by these embodiments, but is defined by the claims.

All publications, patent applications, patents, and other references mentioned in this specification are herein incorporated by reference in their entirety. Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art. In case of conflict, the present specification, definitions, will control.

When the specification derives materials, substances, methods, steps, devices, or elements and the like in the word "known to those skilled in the art", "prior art", or the like, such derived objects encompass those conventionally used in the art at the time of the application, but also include those which are not currently commonly used but which would become known in the art to be suitable for similar purposes.

In the context of this specification, any matters or matters not mentioned are directly applicable to those known in the art without modification except as explicitly stated. Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or ideas thus formed are all deemed to be part of the original disclosure or original description of the present invention, and should not be deemed to be a new matter which has not been disclosed or contemplated herein, unless such combination is clearly unreasonable by those skilled in the art.

In the invention, the specific surface area, pore volume and average pore diameter are measured by an ASAP 2020 type adsorber of Micromeritics company in America, the test temperature is-196 ℃, the sample is degassed at 120 ℃ for 10 hours before the test, and the result is calculated by a Brunauer-Emmett-Teller (BET) method.

In the catalysts of the examples and comparative examples of the present invention, the mass percentage of metal was measured by a Kratos Axis 165 type X-ray photoelectron spectrometer under the test conditions of 15mA and 14kV.

In the invention, the average particle size of metal in the catalyst is calculated by imageJ software in a JEOL 2100 transmission electron microscope, and the acquired sample is 200 particles.

The catalyst prepared by the embodiment of the invention is photographed by a Tecnai F20S-Tain transmission electron microscope by a High Resolution Transmission Electron Microscope (HRTEM), and a field emission electron gun is adopted during photographing, wherein the accelerating voltage is 200kV. The crystal face structure of the catalyst (111) is measured by high-power projection images, namely, the crystal face spacing of diffraction fringes is between 0.2 and 0.3 nm.

Example 1

And (3) placing 200g of each of the corn silk and the plumeria rubra washed by deionized water into a blast drying oven at 60 ℃ for drying for 24 hours, mixing 150g of the dried corn silk and 15g of the dried plumeria rubra, and grinding to 60 meshes. 120g of the ground material was mixed with 60g of 85wt% phosphoric acid and immersed in a blow-drying oven at 60℃for 3 hours. Taking out the immersed material, transferring the immersed material into a tube furnace, and introducing high-purity nitrogen at a flow rate of 80 mL/min; and heating to 200 ℃ at a speed of 5 ℃/min, staying for 2h, heating to 400 ℃ at a speed of 2.5 ℃/min, and carrying out constant temperature treatment for 10h. Naturally cooling the sample subjected to constant temperature treatment to room temperature, taking out, washing with 0.1mol/L hydrochloric acid, repeatedly washing with deionized water to neutrality, and transferring to a blast drying oven at 60 ℃ for drying for 24 hours to obtain the carbon carrier with the phosphorus content of 9.5wt%.

0.1g of yttrium nitrate hexahydrate, 42g of cyanamide, 46g of carbon support were dissolved in 2000g of deionized water, stirred at 260rpm for 30min at 25℃and 0.00031g of silver nitrate was added and stirred at 450rpm for 90min at 25 ℃. The titration time for the aqueous lithium aluminum hydride solution was 27min, wherein the mass of lithium aluminum hydride was 0.09g and the mass of deionized water was 25g, and stirring was continued at 450rpm for 15 hours at 25 ℃. And (3) carrying out suction filtration on the obtained mixture, repeatedly flushing with deionized water, placing the obtained solid in a vacuum drying oven, and drying for 10 hours at the drying temperature of 65 ℃ under the vacuum degree of 133Pa to obtain the bimetallic catalyst A for synthesizing polyether amine. The physicochemical properties are shown in Table 1.

The resulting metal catalyst was characterized by High Resolution Transmission Electron Microscopy (HRTEM) as in fig. 1; as can be seen from FIG. 1, the interplanar spacing of the diffraction fringes is 0.25nm, which corresponds to the (111) lattice structure characteristics, indicating the presence of catalyst A in this lattice structure.

Example 2

The carbon support preparation method is the same as in example 1.

0.1g of yttrium nitrate hexahydrate, 40g of cyanamide, 45g of carbon support were dissolved in 1800g of deionized water, stirred at 200rpm for 20min at 20℃and 0.00028g of silver nitrate was added and stirred at 400rpm for 60min at 20 ℃. The titration time for the aqueous lithium aluminum hydride solution was 19min, wherein the mass of lithium aluminum hydride was 0.085g and the mass of deionized water was 20g, and stirring was continued at 400rpm for 12h at 20 ℃. And (3) carrying out suction filtration on the obtained mixture, repeatedly flushing with deionized water, placing the obtained solid in a vacuum drying oven, and drying for 8 hours at the vacuum degree of 120Pa and the drying temperature of 60 ℃ to obtain the bimetallic catalyst B for synthesizing polyether amine. The physicochemical properties are shown in Table 1.

The resulting polyetheramine bimetallic catalyst was characterized by High Resolution Transmission Electron Microscopy (HRTEM) as in fig. 2; as can be seen from FIG. 2, the interplanar spacing of the diffraction fringes is 0.23nm, which corresponds to the (111) lattice structure characteristics, indicating the presence of catalyst B in this lattice structure.

Example 3

The carbon support preparation method is the same as in example 1.

0.1g of yttrium nitrate hexahydrate, 50g of cyanamide, 50g of carbon support were dissolved in 2600g of deionized water, stirred at 300rpm for 40min at 30℃and 0.00042g of silver nitrate was added, and stirred at 500rpm for 120min at 30 ℃. The titration rate of the aqueous solution of lithium aluminum hydride was 15min, wherein the mass of lithium aluminum hydride was 0.105g, the mass of deionized water was 30g, and stirring was continued at 500rpm for 16h at 30 ℃. And (3) carrying out suction filtration on the obtained mixture, repeatedly flushing with deionized water, placing the obtained solid in a vacuum drying oven, and drying for 12 hours at the drying temperature of 80 ℃ under the vacuum degree of 150Pa to obtain the bimetallic catalyst C for synthesizing polyether amine. The physicochemical properties are shown in Table 1.

Example 4

The carbon support preparation method is the same as in example 1.

Compared with the example 1, lanthanum nitrate hexahydrate is adopted to replace yttrium nitrate hexahydrate, the dosage of the first metal and the second metal is adjusted, and other reaction conditions and material compositions are unchanged, so that the bimetallic catalyst D for synthesizing polyetheramine is obtained. The physicochemical properties are shown in Table 1.

Example 5

The carbon support preparation method is the same as in example 1.

Compared with the example 1, cerium nitrate hexahydrate is adopted to replace yttrium nitrate hexahydrate, the dosage of the first metal and the second metal is adjusted, and other reaction conditions and material compositions are unchanged, so that the bimetallic catalyst E for synthesizing polyetheramine is obtained. The physicochemical properties are shown in Table 1.

The resulting polyetheramine bimetallic catalyst was characterized by High Resolution Transmission Electron Microscopy (HRTEM) as figure 3; as can be seen from FIG. 3, the interplanar spacing of the diffraction fringes is 0.23nm, which corresponds to the (111) lattice structure characteristics, indicating the presence of catalyst E in this lattice structure.

Example 6

The carbon support preparation method is the same as in example 1.

Compared with the example 1, acetonitrile is adopted to replace cyanamide, the dosage of the first metal and the second metal is adjusted, and other reaction conditions and material compositions are unchanged, so that the bimetallic catalyst F for synthesizing polyetheramine is obtained. The physicochemical properties are shown in Table 1.

Example 7

The carbon support preparation method is the same as in example 1.

Compared with the example 1, the bimetallic catalyst G for synthesizing polyetheramine is obtained by adopting propionitrile to replace cyanamide and adjusting the dosage of the first metal and the second metal, and the other reaction conditions and the material composition are unchanged. The physicochemical properties are shown in Table 1.

The resulting polyetheramine bimetallic catalyst was characterized by High Resolution Transmission Electron Microscopy (HRTEM) as in fig. 4; as can be seen from FIG. 4, the interplanar spacing of the diffraction fringes is 0.26nm, which accords with the (111) crystal face structural feature, and shows that the bimetallic catalyst G for synthesizing polyetheramine has the crystal face structure.

Example 8

The carbon support preparation method is the same as in example 1.

Compared with the example 1, stannous chloride is adopted to replace silver nitrate, the dosage of the first metal and the second metal is adjusted, and other reaction conditions and material compositions are unchanged, so that the bimetallic catalyst H for synthesizing polyetheramine is obtained. The physicochemical properties are shown in Table 1.

Example 9

The carbon support preparation method is the same as in example 1.

Compared with the example 1, the bimetallic catalyst I for synthesizing polyetheramine is obtained by adopting indium nitrate to replace silver nitrate and adjusting the dosage of the first metal and the second metal, and keeping other reaction conditions and material composition unchanged. The physicochemical properties are shown in Table 1.

Example 10

The carbon support preparation method is the same as in example 1.

Compared with the example 1, sodium borohydride is adopted to replace lithium aluminum hydride, the dosage of the first metal and the second metal is adjusted, and other reaction conditions and material compositions are unchanged, so that the bimetallic catalyst J for synthesizing polyetheramine is obtained. The physicochemical properties are shown in Table 1.

Example 11

The carbon support preparation method is the same as in example 1.

Compared with the example 1, potassium borohydride is adopted to replace lithium aluminum hydride, the dosage of the first metal and the second metal is adjusted, and other reaction conditions and material compositions are unchanged, so that the bimetallic catalyst K for synthesizing polyetheramine is obtained. The physicochemical properties are shown in Table 1.

Comparative example 1

Compared with the example 1, the bimetallic catalyst L for synthesizing polyetheramine is obtained by adopting coconut shell activated carbon to replace the prepared carbon carrier and adjusting the dosage of the first metal and the second metal, and the other reaction conditions and the material composition are unchanged. The physicochemical properties are shown in Table 1.

The preparation method of the coconut shell activated carbon comprises the following steps: according to the mass ratio of 1:5, weighing coconut shells and hydrochloric acid solution, uniformly mixing, standing, taking out the coconut shells, drying, crushing, sieving, collecting particles, and taking 90 parts of water, 60 parts of sieving particles, 30 parts of peptone, 20 parts of agar, 15 parts of sucrose and 3 parts of sodium dihydrogen phosphate according to parts by weight, stirring, mixing, sterilizing and disinfecting to obtain the nutrient. And (3) uniformly mixing the nutrients and the fungus powder, fermenting in a fermentation tank, centrifugally separating the fermentation mixture, collecting precipitate, and washing with ethanol to obtain the base material. According to the parts by weight, 95 parts of water, 37 parts of base material, 13 parts of ferric nitrate nonahydrate, 11 parts of aluminum isopropoxide, 9 parts of titanium sulfate, 7 parts of sodium carbonate and 5 parts of surfactant are taken, ultrasonic oscillation is carried out, the pH value is regulated to 8 by ammonia water, standing and aging are carried out, spray drying is carried out, and the dried substance is collected. And then placing the dried product into a carbonization furnace, preheating at the temperature of 13 ℃/min to 500 ℃, heating to 700 ℃, preserving heat for 60min, heating to 800 ℃, carbonizing, collecting carbide, washing to be neutral, drying and crushing to obtain the coconut shell activated carbon, wherein the phosphorus content of the coconut shell activated carbon is 0.05wt%.

The resulting bimetallic catalyst L for the synthesis of polyetheramines was characterized by High Resolution Transmission Electron Microscopy (HRTEM) as shown in fig. 5; as can be seen from fig. 5, the catalyst did not form a uniform diffraction fringe structure, i.e., the (111) crystal plane structural feature was not present, indicating that the crystal plane structure of catalyst L was not present.

Comparative example 2

Compared with the example 1, the plumeria rubra is omitted in the process of preparing the carbon carrier, the phosphorus content of the carbon carrier is 16.5 weight percent, and other reaction conditions and material compositions are unchanged, so that the bimetallic catalyst M for synthesizing polyetheramine is obtained. The physicochemical properties are shown in Table 1.

The resulting bimetallic catalyst for the synthesis of polyetheramines was characterized by High Resolution Transmission Electron Microscopy (HRTEM) as shown in fig. 6; as can be seen from FIG. 6, the interplanar spacing of the diffraction fringes is 5nm, which does not conform to the (111) crystal plane structural features, indicating that the bimetallic catalyst M for synthesizing polyetheramine does not have the crystal plane structure.

Comparative example 3

Compared with the example 1, the corn silk is omitted in the process of preparing the carbon carrier, the phosphorus content of the carbon carrier is 15.7wt%, and other reaction conditions and material compositions are unchanged, so that the bimetallic catalyst N for synthesizing polyetheramine is obtained. The physicochemical properties are shown in Table 1.

Comparative example 4

The carbon support preparation method is the same as in example 1.

Compared with example 1, the bimetallic catalyst O for synthesizing polyetheramine is obtained by omitting cyanamide and keeping other reaction conditions and material composition unchanged. The physicochemical properties are shown in Table 1.

Comparative example 5

The carbon support preparation method is the same as in example 1.

Compared with the example 1, the bimetallic catalyst P for synthesizing polyetheramine is obtained by omitting an aqueous solution of lithium aluminum hydride and keeping other reaction conditions and material composition unchanged. The physicochemical properties are shown in Table 1.

Comparative example 6

The carbon support preparation method is the same as in example 1.

Compared with example 1, silver nitrate is omitted, and other reaction conditions and material compositions are unchanged, so that the catalyst Q for synthesizing polyether amine is obtained. The physicochemical properties are shown in Table 1.

Test example 1

Physicochemical properties of the bimetallic catalysts in examples 1-11 and comparative examples 1-6 were measured, and specific results are shown in Table 1.

Table 1 physicochemical properties of the catalysts prepared in examples and comparative examples

Sample of	Sequence number	Specific surface area/m ² ·g ^-1	Pore volume/cm ³ ·g ^-1	Average pore size/nm	First metal content/wt%	Second metal content/wt%	Average particle diameter of metal/nm
								A	Example 1	930	0.84	10.00	2.75	0.050	1.40
B	Example 2	850	0.72	8.73	1.05	0.009	1.68
								C	Example 3	870	0.75	9.00	3.25	0.080	1.70
D	Example 4	830	0.69	8.52	0.75	0.006	1.80
								E	Example 5	850	0.70	8.27	0.86	0.007	1.80
F	Example 6	820	0.65	8.00	4.50	0.095	1.80
								G	Example 7	830	0.67	8.00	5.00	0.100	1.80
H	Example 8	890	0.79	9.00	3.05	0.010	1.77
								I	Example 9	890	0.78	9.00	3.26	0.020	1.80
J	Example 10	900	0.80	9.33	2.17	0.035	1.55
								K	Example 11	880	0.77	9.00	2.25	0.026	1.60
L	Comparative example 1	350	0.35	20.00	0.65	0.005	5.00
								M	Comparative example 2	270	0.45	15.00	0.60	0.002	7.00
N	Comparative example 3	300	0.49	5.75	5.43	0.146	11.00
								O	Comparative example 4	400	0.45	6.00	5.50	0.150	10.00
P	Comparative example 5	370	0.43	6.56	5.80	0.200	10.00
								Q	Comparative example 6	400	0.35	4.59	0.52	—	12.00

As shown in Table 1, the bimetallic catalyst for polyetheramine prepared by the invention has good physicochemical properties, and the average pore diameter is 8 nm-10 nm under the conditions of maintaining a certain specific surface area and Kong Rongqian, thereby providing convenience for the diffusion of the polypropylene glycol and reaction intermediate products thereof in the inner surface and the outer surface of the catalyst. The carbon carrier prepared by the method has developed and compact and uniform pores, and obvious extensibility texture structure exists in the structure of the carbon carrier material, namely, the carbon carrier material has lattice deficiency or defects in the roasting process, so that the metal elements in the first metal salt are beneficial to exist in the catalyst structure in the form of (111) crystal faces (shown in figure 1). As can be seen from Table 1, the average metal particle diameter of the catalyst of the example was generally smaller than that of the catalyst of the comparative example, and the average metal particle diameter of the bimetallic catalyst prepared in example 1 was only 1.4nm. The reason is that the cyano compound is added in the synthesis stage of the catalyst, and the cyano functional group provides additional electron pairs to coordinate with the metal crystal nucleus, so that the oxidation of the metal crystal is effectively reduced, and the infinite growth of the metal crystal is prevented. In addition, in the catalyst of the present invention, since the metal element in the first metal salt exists in the form of the (111) crystal face, the interfacial energy at the time of the coupling reaction with the metal element in the second metal salt is minimal, and ultra-small clusters are easily formed therebetween.

Test example 2

The catalytic effect of the polyether amine bimetallic catalysts of examples 1-11 and comparative examples 1-6 on the synthesis of polyether amine (D-230) from polypropylene glycol (230) was determined. Taking 5g of catalyst, 80g of polypropylene glycol and 100g of ammonia water (28-30wt%) and reacting for 2.5h at the reaction temperature of 140 ℃ and the reaction pressure of 3.5MPa with the stirring rotation speed of 550 rpm. The test results are shown in Table 2, wherein the primary amine product is the main product of polyetheramine.

Table 2 catalytic effect of the catalysts prepared in examples and comparative examples

Sample of	Polypropylene glycol conversion%	Primary amine product selectivity%	Polypropylene glycol conversion after half a year of continuous operation%	Primary amine product selectivity after half a year of continuous operation
					A	99.3	99.9	98.9	99.7
B	98.5	99.4	98.1	99.1
					C	98.8	99.6	98.3	99.2
D	98.3	99.3	98.04	99.06
					E	98.5	99.3	98.2	99.05
F	98.2	99.2	98.02	99.01
					G	98.3	99.4	98.07	99.1
H	98.7	99.5	98.2	99.1
					I	98.6	99.3	98.1	99.02
J	99.0	99.6	98.3	99.1
					K	98.8	99.3	98.2	99.05
L	75.7	80.6	60.9	72.5
					M	68.5	73.4	60.1	64.3
N	71.9	75.6	63.2	68.5
					O	70.5	61.0	58.9	52.1
P	69.6	62.3	59.0	52.3
					Q	72.5	65.6	63.4	57.6

As can be seen from Table 2, the bimetallic catalyst for synthesizing polyetheramine prepared by the present invention has good catalytic activity, selectivity and service life. In the bimetallic catalysts prepared in example 1 and example 2, the precipitation of metal particles or clusters did not occur after half a year of use, whereas the precipitation of metal particles or clusters was very remarkable in the comparative sample, resulting in a reduction in the service life of the catalyst. The polypropylene glycol conversion and primary amine product D-230 selectivity remained at 98.9% and 99.7% after half a year for the example 1 sample.

Claims

1. A bimetallic catalyst for synthesizing polyetheramine, the catalyst comprising a support, a first metal and a second metal, wherein the first metal is selected from at least one element of lanthanum, cerium and yttrium, and the second metal is selected from at least one element of silver, tin and indium; the mass of the catalyst is taken as a reference, the first metal content is 0.75 to 5.0 weight percent, and the second metal content is 0.006 to 0.1 weight percent;

the carrier of the catalyst is a carbon carrier, and the carbon carrier is obtained by roasting corn silk and plumeria rubra in a combined way; corn silk and plumeria rubra according to the mass ratio of 1: (0.05-0.25) mixing;

the specific surface area of the catalyst is 820m ² /g～930m ² Per g, pore volume of 0.65cm ³ /g～0.84cm ³ And/g, the average pore diameter is 8 nm-10 nm, and the metal grain size is 1.4 nm-1.8 nm.

2. The catalyst of claim 1 wherein the first metal is yttrium; the second metal is silver.

3. The method for preparing the bimetallic catalyst for synthesizing polyetheramine according to claim 1 or 2, comprising the following steps:

(3) Filtering, washing and drying the mixture obtained in the step (2) to obtain a bimetallic catalyst for synthesizing polyether amine;

the mass ratio of the first metal salt to the cyano compound to the carbon carrier to the water to the second metal salt in the step (1) is 1: (300-600): (350-650): (10000-33000): (0.0015 to 0.0065);

the carbon carrier in the step (1) is obtained by combined roasting of corn silk and plumeria rubra;

the preparation method of the carbon carrier in the step (1) comprises the following steps: corn silk and plumeria rubra are mixed according to the mass ratio of corn silk to plumeria rubra of 1: (0.05-0.25), mixing and grinding, and mixing the ground material with an acid solution according to the mass ratio of 1: (0.3-1), and then drying and roasting to obtain a carbon carrier;

the reducing agent in the step (2) is at least one selected from sodium borohydride, lithium aluminum hydride and potassium borohydride; the dosage of the aqueous solution of the reducing agent in the step (2) is (0.75-1.25) according to the mass ratio of the reducing agent to the water to the first metal salt: (150-350): 1.

4. the method according to claim 3, wherein the first metal salt in the step (1) is at least one selected from lanthanum nitrate hexahydrate, cerium nitrate hexahydrate and yttrium nitrate hexahydrate; the second metal salt is at least one selected from silver nitrate, stannous chloride and indium nitrate.

5. A method of preparing according to claim 3, wherein the first metal salt of step (1) is yttrium nitrate hexahydrate; the second metal salt is silver nitrate.

6. A process according to claim 3, wherein the cyano compound of step (1) is at least one selected from acetonitrile, propionitrile and cyanamide.

7. A process according to claim 3, wherein the cyano compound of step (1) is cyanamide.

8. A method according to claim 3, wherein the mass ratio of the first metal salt, the cyano compound, the carbon carrier, the water and the second metal salt in step (1) is 1: (400-500): (450-500): (18000-26000): (0.0028 to 0.0042).

9. A method of preparing as claimed in claim 3, wherein the acid solution has a mass concentration of 70 to 90wt%.

10. A process according to claim 3, wherein the reducing agent in step (2) is lithium aluminum hydride.

11. The method according to claim 3, wherein the aqueous solution of the reducing agent in the step (2) is used in an amount of (0.85 to 1.05) in terms of the mass ratio of the reducing agent, water and the first metal salt: (200-300): 1, a step of; the titration time of the dropwise addition in the step (2) is 5-45 min.

12. The method according to claim 3, wherein the titration time of the dropwise addition in the step (2) is 15min to 30min.

13. The method according to claim 3, wherein the drying in step (3) is performed in a vacuum drying oven, the vacuum degree is 120 Pa-150 Pa, the drying temperature is 60 ℃ to 80 ℃, and the drying time is 8 h-12 h.

14. Use of the catalyst of any one of claims 1 or 2 or the catalyst prepared by the preparation method of any one of claims 3 to 13 in the synthesis of polyetheramines from polyether polyols.

15. The method of claim 14, wherein the raw polyether polyol is a polypropylene glycol having an average molecular weight of less than 500.

16. The method according to claim 14, wherein the mass ratio of the catalyst, the polypropylene glycol and the ammonia water is 1: (16-26): (14-24), wherein the mass concentration of ammonia water is 28-30wt%, and the reaction conditions for synthesizing polyether amine from polyether polyol are as follows: the reaction temperature is 140-170 ℃, the reaction pressure is 2.5-4.5 MPa, and the reaction time is 1.5-4.5 h.