Platinum-supported catalyst, preparation method thereof and application thereof in cyclododecanol synthesis
阅读说明：本技术 一种铂负载催化剂及其制备方法和在合成环十二醇中的应用 (Platinum-supported catalyst, preparation method thereof and application thereof in cyclododecanol synthesis ) 是由 曾伟 王磊 黎源 赵欣 蒋玉鑫 杨恒东 丁可 宋延方 杨洋 陈永 于 2019-12-09 设计创作，主要内容包括：本发明提供一种铂负载催化剂及其制备方法和在合成环十二醇中的应用,所述铂负载催化剂的载体为聚酰胺-胺超分子接枝改性的泡沫石墨烯,采用该铂负载催化剂合成环十二醇时,具有收率高、杂质低的优点。(The invention provides a platinum-supported catalyst, a preparation method thereof and application thereof in cyclododecanol synthesis.)
1. A preparation method of a platinum supported catalyst is characterized by comprising the following steps:
1) oxidizing foam graphene powder FG serving as a raw material by a Hummers method to obtain oxidized foam graphene OFG;
2) taking the oxidized foam graphene OFG prepared in the step 1) as a raw material, and carrying out polyamide-amine supramolecular grafting modification on the oxidized foam graphene OFG to prepare a catalyst carrier SMOFG;
3) soaking the prepared catalyst carrier SMOFG in a chloroplatinic acid solution, then taking out, reacting the catalyst carrier soaked with the chloroplatinic acid for 5-16 h at 30-50 ℃ under the atmosphere of carbon monoxide and water, then heating to 180-250 ℃, and reacting for 10-40 min to obtain the polyamide-amine supermolecule graft modified foamed graphene carrier-loaded platinum catalyst.
2. The method for producing a platinum-supported catalyst according to claim 1, wherein the oxidizing by the Hummers method in step 1) comprises: FG, H foamed graphene powder2SO4And H3PO4Mixing, stirring to obtain solution, and adding KMnO4Slowly adding into the above solution, and stirring for 20min-40 min; fully stirring for 1-3 h while keeping the temperature of the system at 35-50 ℃; when the temperature is raised to 80-95 ℃, fully stirring for 1-3 h; subsequently, deionized water and H were slowly added dropwise2O2And (3) carrying out solid-liquid separation on the mixed solution, and carrying out vacuum freeze drying on the solid to obtain the oxidized foam graphene powder OFG.
3. The method for preparing the platinum-supported catalyst according to claim 1, wherein the performing of the polyamidoamine supramolecular graft modification in step 2) comprises: placing OFG in a solvent for uniform dispersion, adding hexamethylenediamine for uniform mixing to obtain a mixture, reacting the mixture at 180-220 ℃ for 6-10 h, cooling, washing, filtering and drying to obtain an intermediate M; mixing the intermediate M with methyl acrylate and methanol, reacting for 15-20 h under stirring and inert gas protection and at room temperature, filtering, washing and drying to obtain a catalyst carrier SMOFG;
preferably, in the step 2), the polyamide-amine content in the catalyst carrier is 5-20% of the total mass of the catalyst carrier.
4. The preparation method of the platinum-supported catalyst according to claim 1, wherein in the step 3), the mass fraction of the chloroplatinic acid in the chloroplatinic acid solution is 2.5 to 5 wt%, and the mass ratio of the catalyst carrier to the chloroplatinic acid solution is 3 to 10 wt%; the dipping time is 15-30 min.
5. A platinum supported catalyst prepared according to the process of any one of claims 1 to 4.
6. The platinum supported catalyst according to claim 5, wherein the catalyst particle size is 5 to 800nm, preferably 10 to 250nm, more preferably 30 to 75nm, and the catalyst Pt content is 0.1 to 10 wt%, preferably 0.3 to 3.5 wt%, more preferably 0.5 to 1 wt%.
7. Use of a platinum supported catalyst prepared according to the process of any one of claims 1 to 4 for the preparation of cyclododecanol.
8. A method for synthesizing cyclododecanol by using the platinum-supported catalyst prepared by the method of any one of claims 1 to 4, wherein the method comprises the step of subjecting 9, 10-epoxy-1, 5-cyclododecadiene and the platinum-supported catalyst to hydrogenation reaction in a reactor at a reaction temperature of 40 to 250 ℃ and a reaction pressure of 0.5 to 30MPa to prepare cyclododecanol.
9. The method for synthesizing cyclododecanol according to claim 8, wherein the inside of the reactor contains a plurality of micro reaction tubes; preferably, the micro-reaction tubes are symmetrically and uniformly distributed on the cross section of the reactor, and the number of the micro-reaction tubes is 5-100, preferably 10-60, and more preferably 20-45; the wall thickness of the micro-reaction tube is 0.1-25 mm, preferably 0.3-5 mm, and more preferably 1-3 mm; the length-diameter ratio of the micro-reaction tube is 5-120, preferably 10-80, and more preferably 25-60.
10. The method for synthesizing cyclododecanol according to claim 8 or 9, wherein the reactor is preheated before adding raw materials, in a preferred embodiment, the preheating is performed by introducing heated hydrogen into the reactor, and the temperature of the hydrogen in the preheating stage is 50-200 ℃, preferably 75-160 ℃, and more preferably 100-120 ℃; the hydrogen flow rate in the preheating stage is 20-350L/h, preferably 50-220L/h, and more preferably 100-160L/h.
11. The method for synthesizing cyclododecanol according to claim 9, wherein the micro-reaction tube comprises an upper section and a lower section, the diameter of the lower section is larger than that of the upper section, preferably, the ratio of the height of the upper section to the height of the lower section of the micro-reaction tube is 1-10: 1, preferably 2-7: 1, more preferably 3-5: 1; the inner diameter of the upper section is 0.1-50 mm, preferably 5-35 mm, and more preferably 10-20 mm; the inner diameter of the lower section is 0.5-100 mm, preferably 10-60 mm, and more preferably 25-45 mm.
12. The method for synthesizing cyclododecanol according to claim 9, wherein the interior of the micro-reaction tube is provided with a double helix structure internal member, the double helix structure internal member is provided at an upper section of the micro-reaction tube, and the lower section is provided with no internal member and is an empty tube.
13. The process for synthesizing cyclododecanol as claimed in any of claims 8 to 12, wherein the starting materials 9, 10-epoxy-1, 5-cyclododecadiene, a platinum-supported catalyst and preheated hydrogen are introduced from the lower end of the reactor and the upper end is an outlet.
14. The method for synthesizing cyclododecanol according to any one of claims 8 to 12, wherein the hydrogenation reaction temperature is 60 to 180 ℃, preferably 125 to 160 ℃; the reaction pressure is 1.5-20 Mpa, preferably 3-12 Mpa; the mass airspeed is 0.01-5 gCDDO/gCatalyst and process for preparing samePreferably 0.05 to 2.5 g/hCDDO/gCatalyst and process for preparing sameMore preferably 0.1 to 1 g/hCDDO/gCatalyst and process for preparing sameH; the gas-oil ratio is 5-5000: 1, preferably 250-2500: 1, and more preferably 300-800: 1.
15. Cyclododecanol synthesized according to any one of claims 8 to 12, having a purity of 98 wt.% or more, a content of organic impurities of < 2 wt.% and a content of metals of < 5 ppm; the organic impurities are one or more of cyclododecane, 1, 2-epoxycyclododecane, cyclododecanone, 1,5, 9-cyclododecatriene, 1,2,9, 10-diepoxycyclododecane, 1, 2-cyclododecanediol and dodecane; the metal is one or more of Fe, Al, Ni, Na, K, Mg, Ca and Co.
Technical Field
The invention relates to the technical field of cyclododecanol preparation, in particular to a platinum-supported catalyst, a preparation method thereof and application thereof in cyclododecanol synthesis.
Background
Cyclododecanol (CDOL) is an important intermediate in the field of engineering plastics, and is an essential intermediate raw material for preparing high-performance nylon 12 or nylon 1212. Meanwhile, cyclododecanol is also an important intermediate of chemical raw materials, and cyclododecanone obtained by dehydrogenation is an important raw material for preparing muscone and musk pyridine in the perfume industry.
At present, the large-scale supply of high-purity cyclododecanol products is not available in the market, and the product has more impurities, so that the downstream application of the product is influenced. This is mainly related to the process for the preparation of cyclododecanol. Cyclododecanol is generally prepared by a Cyclododecane (CDA) oxidation method, but cyclododecane conversion rate is low, byproducts are more, and the yield of target product cyclododecanol is less than 20%; meanwhile, the oxidation reaction process has strict requirements on equipment. US3419615, by modifying the cyclododecane oxidation process, has shown that cyclododecanol yields of up to 80% are not desirable. EP1051380 proposes the decomposition of cyclododecyl hydroperoxide formed in the oxidation of cyclododecane to cyclododecanol and Cyclododecanone (CDON) using a Cr salt as a catalyst, which increases the cyclododecanol yield, but the extent of the increase is rather limited and Cr salts are present in significant residues in cyclododecanol. US6608235 proposes that Ni is used as catalyst, the cyclododecanol hydrogenation yield can reach 95%, but addition of assistant base (NaOH, triethylamine, etc.) is needed to improve the selectivity of cyclododecanol, and the addition of assistant will affect the composition of the final cyclododecanol product.
In summary, the prior art still has certain disadvantages in different degrees, the yield of cyclododecanol is not ideal, and the impurity of cyclododecanol is still to be improved, which affects the downstream use.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a platinum-supported catalyst, a preparation method thereof and application thereof in cyclododecanol synthesis.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a preparation method of a platinum supported catalyst, which comprises the following steps:
1) oxidizing foam graphene powder FG serving as a raw material by a Hummers method to obtain oxidized foam graphene OFG;
2) taking the oxidized foam graphene OFG prepared in the step 1) as a raw material, and carrying out polyamide-amine supramolecular grafting modification on the oxidized foam graphene OFG to prepare a catalyst carrier SMOFG;
3) soaking the prepared catalyst carrier SMOFG in a chloroplatinic acid solution, then taking out, reacting the catalyst carrier soaked with the chloroplatinic acid for 5-16 h at 30-50 ℃ under the atmosphere of carbon monoxide and water, then heating to 180-250 ℃, and reacting for 10-40 min to obtain the polyamide-amine supermolecule graft modified foamed graphene carrier-loaded platinum catalyst.
In a preferred embodiment of the process according to the invention, in step 1), said oxidation by the Hummers method comprises: FG, H foamed graphene powder2SO4And H3PO4Mixing, stirring to obtain solution, and adding KMnO4Slowly adding into the above solution, and stirring for 20min-40 min; fully stirring for 1-3 h while keeping the temperature of the system at 35-50 ℃; when the temperature is raised to 80-95 ℃, fully stirring for 1-3 h; subsequently, deionized water and H were slowly added dropwise2O2And (3) performing solid-liquid separation on the mixed solution, and performing vacuum freeze drying on the solid (for example, performing vacuum freeze drying for 16-30 hours at the temperature of 0-5 ℃) to obtain the oxidized graphene foam powder OFG.
Preferably, in the step 1), 5-15 g of foam graphene powder FG and 500-1000 ml of H are added2SO4And 100 to 250mlH3PO4Mixing and stirring the mixture fully to obtain a solution, and adding 45-80 g of KMnO4Slowly adding into the above solution, and stirring for 20min-40 min; fully stirring for 1-3 h while keeping the temperature of the system at 35-50 ℃; when the temperature is raised to 80-95 ℃, fully stirring for 1-3 h; then slowly dropping 800-1300 ml of deionized water and 150-250 ml of H2O2And (3) carrying out solid-liquid separation on the mixed solution, and carrying out vacuum freeze drying on the solid to obtain the oxidized foam graphene powder OFG.
In a preferred embodiment of the process according to the invention, in step 2), said performing polyamidoamine supramolecular graft modification comprises: placing OFG in a solvent for uniform dispersion, adding hexamethylenediamine for uniform mixing to obtain a mixture, reacting the mixture at 180-220 ℃ for 6-10 h, cooling, washing, filtering and drying to obtain an intermediate M; and mixing the intermediate M with methyl acrylate and methanol, reacting for 15-20 h under the conditions of stirring and inert gas protection and room temperature, filtering, washing and drying to obtain the catalyst carrier SMOFG.
Preferably, in the step 2), 10-20 g of OFG is placed in 200-500 ml of solvent for uniform dispersion through ultrasound, then 0.5-1 g of hexamethylenediamine is added and uniformly mixed to obtain a mixture, the mixture reacts at 180-220 ℃ for 6-10 h, and the mixture is cooled, washed, filtered and dried to obtain an intermediate M; and mixing the intermediate M with 0.5-1 g of methyl acrylate and 10-35 g of methanol, reacting for 15-20 h under the conditions of stirring, inert gas protection and room temperature, filtering, washing and drying to obtain the catalyst carrier SMOFG. The solvent is an alcohol solvent, preferably ethylene glycol.
In the method of the present invention, preferably, in the step 2), the content of the polyamide-amine in the catalyst carrier is 5% to 20% of the total mass of the catalyst carrier. The polyamide-amine content is measured by roasting, the catalyst carrier is roasted for 6-8 hours at 700-800 ℃, and the polyamide-amine content can be calculated by weight loss.
In a preferred embodiment of the method of the present invention, in step 3), the mass fraction of chloroplatinic acid in the chloroplatinic acid solution is 2.5 to 5 wt%, and the mass ratio of the catalyst carrier to the chloroplatinic acid solution is 3 wt% to 10 wt%; the dipping time is 15-30 min.
The catalyst prepared by the method is a polyamide-amine supermolecule graft modified foam graphene loaded nano platinum catalyst, the polyamide-amine supermolecule structure can greatly increase the specific surface area of a catalyst carrier, and simultaneously plays a role of a template agent in the preparation process of the catalyst, so that nano Pt is formed in supermolecule pore channels, and the loss of an active component Pt can be effectively prevented; in addition, the polyamide-amine supermolecule has terminal amino groups, can provide alkalescence for the catalyst, and can improve the CDDO conversion rate and the CDOL selectivity.
The letter M in the "intermediate M" herein is merely a code employed for convenience of description and hereinafter referred to, and has no particular technical connotation.
The term "room temperature condition" as used herein means the same temperature as the indoor environment without the auxiliary temperature control means. Typically 15-30 ℃.
A second aspect of the present invention provides a platinum supported catalyst prepared by the method described above.
In a preferred embodiment of the present invention, the catalyst has a particle size of 5 to 800nm, preferably 10 to 250nm, and more preferably 30 to 75nm, and the catalyst has a Pt content of 0.1 to 10%, preferably 0.3 to 3.5%, and more preferably 0.5 to 1%.
The third aspect of the present invention provides the use of the platinum-supported catalyst prepared by the above-described method for the preparation of cyclododecanol.
In the fourth aspect of the present invention, the method for synthesizing cyclododecanol by using the platinum supported catalyst prepared by the above method is provided, wherein the
In a preferred embodiment according to the present invention, the reactor comprises a plurality of micro-reaction tubes; preferably, the micro-reaction tubes are symmetrically and uniformly distributed on the cross section of the reactor, and the number of the reaction tubes is 5-100, preferably 10-60, and more preferably 20-45; the wall thickness of the micro-reaction tube is 0.1-25 mm, preferably 0.3-5 mm, and more preferably 1-3 mm; the length-diameter ratio of the micro-reaction tube is 5-120, preferably 10-80, and more preferably 25-60.
According to a preferred embodiment of the invention, the reactor is preheated in advance before the raw materials are added into the reactor, in a preferred scheme, the reactor is preheated by introducing heated hydrogen into the reactor, and the temperature of the hydrogen in the preheating stage is 50-200 ℃, preferably 75-160 ℃, and more preferably 100-120 ℃; the hydrogen flow rate in the preheating stage is 20-350L/h, preferably 50-220L/h, and more preferably 100-160L/h. Preferably, the reactor may be a column reactor.
The invention uses a reactor containing a plurality of micro-reaction tubes, meanwhile, the catalyst is foam graphite loaded Pt catalyst with very low density, the lower end of the reactor is liquid phase reaction, because the reaction stage is just started, the CDDO concentration of the raw material is high, the reaction is fast, the heat release power is large, and the liquid phase reaction can effectively control the temperature rise; by means of large-flow hydrogen and low-density catalyst, the hydrogen can carry the catalyst and reaction liquid out from the liquid phase at the lower end of the reactor, and a gas-solid phase reaction is formed at the upper section of the reactor, so that the gas-solid phase reaction rate is higher, the CDDO hydrogenation intermediate can quickly react to generate CDOL, and the conversion rate is improved.
In a preferred embodiment of the present invention, the micro reaction tube comprises an upper section and a lower section, wherein the upper section is thin and small in diameter, and the lower section is thick and large in diameter, i.e. the lower end of the micro reaction tube is expanded; in a preferable scheme, the ratio of the height of the upper section to the height of the lower section is 1-10: 1, preferably 2-7: 1, and more preferably 3-5: 1; the inner diameter of the upper section is 0.1-50 mm, preferably 5-35 mm, and more preferably 10-20 mm; the inner diameter of the lower section is 0.5-100 mm, preferably 10-60 mm, and more preferably 25-45 mm.
In a preferred embodiment of the present invention, the interior of the micro-reaction tube is provided with a double helix structure internal member, the double helix structure internal member is arranged at the upper section of the micro-reaction tube, and the lower section is an empty tube without an internal member. The double-helix structure is arranged in the reaction tube, so that the gas flow disturbance and back-mixing in the gas-solid phase reaction process at the upper section of the reactor can be increased, the mass transfer and retention time can be increased, and the conversion rate and the selectivity of a target product can be improved.
In a preferred embodiment according to the present invention, the feedstock CDDO, platinum supported catalyst and preheated hydrogen are fed from the lower end of the reactor, the upper end being the outlet. The lower section of the reactor is provided with a liquid holding part for generating gas-liquid-solid three-phase reaction, the upper section of the reactor is gas-solid reaction, and hydrogen carries a catalyst and reactants to enter a catalyst recoverer from the top of the reactor. The catalyst recoverer consists of a demister and a liquid receiving tank, the catalyst recovered by the liquid receiving tank is recycled into the reactor, and the gas-phase reaction liquid is collected into the product tank after being condensed.
In a preferred embodiment of the present invention, the hydrogenation reaction temperature is preferably 60 to 180 ℃, more preferably 125 to 160 ℃; the reaction pressure is preferably 1.5-20 Mpa, and more preferably 3-12 Mpa; the mass space velocity (CDDO feed rate) is 0.01-5 gCDDO/gCatalyst and process for preparing samePreferably 0.05 to 2.5 g/hCDDO/gCatalyst and process for preparing sameMore preferably 0.1 to 1 g/hCDDO/gCatalyst and process for preparing sameH; the gas-oil ratio (molar ratio of hydrogen to CDDO) is 5-5000: 1, preferably 250-2500: 1, and more preferably 300-800: 1.
The fifth aspect of the present invention provides cyclododecanol obtained by the above synthesis method, wherein the purity of the cyclododecanol is not less than 98 wt%, the cyclododecanol contains organic impurities other than cyclododecanol, the content of the organic impurities is less than 2 wt%, and the cyclododecanol contains metal, the content of the metal is less than 5ppm (by mass). Wherein the organic impurities except cyclododecanol are one or more of Cyclododecane (CDA), 1, 2-Epoxycyclododecane (ECDA), Cyclododecanone (CDON), cyclododecanone, 1,5, 9-cyclododecatriene, 1,2,9, 10-diepoxycyclododecane, 1, 2-cyclododecanediol and dodecane; the metal in the cyclododecanol is one or more of Fe, Al, Ni, Na, K, Mg, Ca and Co.
"a plurality" of "one or more" as described herein means "two or more". The pressure in the present invention is absolute pressure.
As used herein, "mass space velocity" refers to the amount of feedstock processed per unit time and per unit mass of catalyst.
The technical scheme provided by the invention has the following beneficial effects:
the method firstly provides the polyamide-amine supramolecular graft modified graphene foam loaded nano platinum catalyst which is high in activity and can improve the CDDO conversion rate and the CDOL selectivity. When the catalyst is applied to the synthesis of cyclododecanol, the preparation of cyclododecanol can be carried out under the condition of no solvent due to high CDOL selectivity and yield, reaction liquid does not need to be separated, and a high-purity cyclododecanol product can be obtained at the outlet of a reactor, so that the synthesis process of cyclododecanol is greatly simplified, the process is simple, the refining procedures are reduced, and the energy consumption and the cost are greatly reduced; in addition, because a solvent is not needed, the influence of impurities introduced into the solvent on the final quality of the cyclododecanol is avoided, and simultaneously, the alkalescence provided by the terminal amino group of the outer loading body after the mass transfer of gas and liquid in the reactor is strengthened can obtain the cyclododecanol with high yield under the condition of not adding an auxiliary agent, so that the whole preparation process is simple in material system, no special impurities are introduced, the metal content in the cyclododecanol product is low, and the downstream use requirements are met.
Therefore, compared with the prior art, the cyclododecanol obtained by the method has high yield and high purity; and the synthesis process is simple and the production efficiency is high.
Drawings
FIG. 1 is a schematic Transmission Electron Microscope (TEM) representation of the catalyst CAT-1 prepared in example 1.
Fig. 2 is a schematic representation of the polyamide-amine supramolecular structure prepared in example 1.
FIG. 3 is a schematic Transmission Electron Microscope (TEM) representation of CAT-4 prepared in example 4.
FIG. 4 is a schematic flow chart of a cyclododecanol synthesis reaction system according to example 10;
FIG. 5 is a schematic view of the structure of the micro-reaction tube in example 10;
FIG. 6 is a schematic cross-sectional view of the reactor in example 10;
FIG. 7 is a schematic diagram of the double helix inner member of the micro-reactor of FIG. 5;
wherein, 1 is a hydrogen feeding pipeline, 2 is a raw material CDDO feeding pipeline, 3 is a catalyst feeding pipeline, 4 is a reactor, 5 is a demister, 6 is a liquid receiver, 7 is a condenser, 8 is a product tank, 9 is an upper section of a micro-reaction tube, and 10 is a lower section of the micro-reaction tube.
Detailed Description
In order to better understand the technical solution of the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.
The following is a description of the relevant methods used or possible to be used in the examples or comparative examples of the invention: samples were diluted with chromatographic ethanol and subjected to GC analysis on SHIMADZU AOC-20i using HP-88 (88% -cyanopropyl-aryl-polysiloxane, 100 m.times.0.25 mm.times.0.20 μm) capillary chromatography column, FID detector. The sample inlet temperature is 280 ℃, the detector temperature is 300 ℃, and the column temperature is controlled by adopting a programmed temperature rise method: the initial column temperature was maintained at 50 ℃ for 0.5 min, the temperature was raised to 120 ℃ at 3 ℃/min for 5min, and then raised to 220 ℃ at 20 ℃/min. Column pressure 77.3kpa, column flow 1.1ml/min, split ratio 1: 50, sample size: 0.2. mu.L. Conversion and selectivity were calculated using area normalization.
The metal content in the catalyst and the product is measured by ICP (inductively coupled plasma spectrometer).
The above methods are common general knowledge in the art, and are not described in detail.
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