CN114011462A - Polyaniline loaded zinc catalyst and preparation method and application thereof - Google Patents
Polyaniline loaded zinc catalyst and preparation method and application thereof Download PDFInfo
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- CN114011462A CN114011462A CN202111372163.9A CN202111372163A CN114011462A CN 114011462 A CN114011462 A CN 114011462A CN 202111372163 A CN202111372163 A CN 202111372163A CN 114011462 A CN114011462 A CN 114011462A
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- 239000003054 catalyst Substances 0.000 title claims abstract description 66
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 title claims abstract description 57
- 229910052725 zinc Inorganic materials 0.000 title claims abstract description 57
- 239000011701 zinc Substances 0.000 title claims abstract description 57
- 229920000767 polyaniline Polymers 0.000 title claims abstract description 29
- 238000002360 preparation method Methods 0.000 title claims abstract description 21
- PAYRUJLWNCNPSJ-UHFFFAOYSA-N N-phenyl amine Natural products NC1=CC=CC=C1 PAYRUJLWNCNPSJ-UHFFFAOYSA-N 0.000 claims abstract description 56
- 150000003751 zinc Chemical class 0.000 claims abstract description 43
- 239000007864 aqueous solution Substances 0.000 claims abstract description 42
- JJTUDXZGHPGLLC-UHFFFAOYSA-N lactide Chemical compound CC1OC(=O)C(C)OC1=O JJTUDXZGHPGLLC-UHFFFAOYSA-N 0.000 claims abstract description 24
- 238000002156 mixing Methods 0.000 claims abstract description 19
- 230000001590 oxidative effect Effects 0.000 claims abstract description 17
- 239000003513 alkali Substances 0.000 claims abstract description 16
- 239000002253 acid Substances 0.000 claims abstract description 15
- 238000001035 drying Methods 0.000 claims abstract description 15
- 239000007788 liquid Substances 0.000 claims abstract description 12
- 238000011068 loading method Methods 0.000 claims abstract description 10
- 238000000926 separation method Methods 0.000 claims abstract description 9
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 9
- 238000004519 manufacturing process Methods 0.000 claims abstract description 5
- 239000000243 solution Substances 0.000 claims description 80
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 48
- 150000001448 anilines Chemical class 0.000 claims description 45
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 claims description 36
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 28
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 19
- BHAAPTBBJKJZER-UHFFFAOYSA-N p-anisidine Chemical compound COC1=CC=C(N)C=C1 BHAAPTBBJKJZER-UHFFFAOYSA-N 0.000 claims description 18
- 239000011592 zinc chloride Substances 0.000 claims description 18
- 235000005074 zinc chloride Nutrition 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 17
- 239000012266 salt solution Substances 0.000 claims description 16
- 239000011259 mixed solution Substances 0.000 claims description 15
- 239000011787 zinc oxide Substances 0.000 claims description 14
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- 230000003647 oxidation Effects 0.000 claims description 12
- 238000007254 oxidation reaction Methods 0.000 claims description 12
- 239000002244 precipitate Substances 0.000 claims description 12
- HRXZRAXKKNUKRF-UHFFFAOYSA-N 4-ethylaniline Chemical compound CCC1=CC=C(N)C=C1 HRXZRAXKKNUKRF-UHFFFAOYSA-N 0.000 claims description 10
- 239000011260 aqueous acid Substances 0.000 claims description 10
- RZXMPPFPUUCRFN-UHFFFAOYSA-N p-toluidine Chemical compound CC1=CC=C(N)C=C1 RZXMPPFPUUCRFN-UHFFFAOYSA-N 0.000 claims description 10
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 9
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 9
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 7
- 239000007800 oxidant agent Substances 0.000 claims description 7
- 239000007790 solid phase Substances 0.000 claims description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 6
- 230000015572 biosynthetic process Effects 0.000 claims description 6
- ONDPHDOFVYQSGI-UHFFFAOYSA-N zinc nitrate Chemical compound [Zn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ONDPHDOFVYQSGI-UHFFFAOYSA-N 0.000 claims description 6
- ZBHRMUJBIBUTLB-UHFFFAOYSA-N 2-propan-2-yloxybenzene-1,4-diamine Chemical compound CC(C)OC1=CC(N)=CC=C1N ZBHRMUJBIBUTLB-UHFFFAOYSA-N 0.000 claims description 5
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 0.000 claims description 5
- PKMIIMPMZIHGAJ-UHFFFAOYSA-N 2-ethoxybenzene-1,4-diamine Chemical compound CCOC1=CC(N)=CC=C1N PKMIIMPMZIHGAJ-UHFFFAOYSA-N 0.000 claims description 4
- FTZQXOJYPFINKJ-UHFFFAOYSA-N 2-fluoroaniline Chemical compound NC1=CC=CC=C1F FTZQXOJYPFINKJ-UHFFFAOYSA-N 0.000 claims description 4
- HGUYBLVGLMAUFF-UHFFFAOYSA-N 2-methoxybenzene-1,4-diamine Chemical compound COC1=CC(N)=CC=C1N HGUYBLVGLMAUFF-UHFFFAOYSA-N 0.000 claims description 4
- KRZCOLNOCZKSDF-UHFFFAOYSA-N 4-fluoroaniline Chemical compound NC1=CC=C(F)C=C1 KRZCOLNOCZKSDF-UHFFFAOYSA-N 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 3
- ZOIORXHNWRGPMV-UHFFFAOYSA-N acetic acid;zinc Chemical compound [Zn].CC(O)=O.CC(O)=O ZOIORXHNWRGPMV-UHFFFAOYSA-N 0.000 claims description 3
- 229910017604 nitric acid Inorganic materials 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 239000004246 zinc acetate Substances 0.000 claims description 3
- 229960001763 zinc sulfate Drugs 0.000 claims description 3
- 229910000368 zinc sulfate Inorganic materials 0.000 claims description 3
- 230000003287 optical effect Effects 0.000 abstract description 13
- 238000006116 polymerization reaction Methods 0.000 abstract description 5
- 238000006555 catalytic reaction Methods 0.000 abstract description 4
- 230000003472 neutralizing effect Effects 0.000 abstract description 4
- 231100000053 low toxicity Toxicity 0.000 abstract description 3
- 229910052751 metal Inorganic materials 0.000 abstract description 3
- 239000002184 metal Substances 0.000 abstract description 3
- 238000001308 synthesis method Methods 0.000 abstract description 2
- 125000002490 anilino group Chemical class [H]N(*)C1=C([H])C([H])=C([H])C([H])=C1[H] 0.000 abstract 2
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 10
- 230000003197 catalytic effect Effects 0.000 description 9
- 239000004310 lactic acid Substances 0.000 description 9
- 235000014655 lactic acid Nutrition 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 8
- 239000004626 polylactic acid Substances 0.000 description 8
- 229920000747 poly(lactic acid) Polymers 0.000 description 7
- 239000000047 product Substances 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 6
- CBCKQZAAMUWICA-UHFFFAOYSA-N 1,4-phenylenediamine Chemical compound NC1=CC=C(N)C=C1 CBCKQZAAMUWICA-UHFFFAOYSA-N 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 239000002585 base Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 125000001424 substituent group Chemical group 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- JVTAAEKCZFNVCJ-REOHCLBHSA-N L-lactic acid Chemical compound C[C@H](O)C(O)=O JVTAAEKCZFNVCJ-REOHCLBHSA-N 0.000 description 2
- 125000003277 amino group Chemical group 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000002524 electron diffraction data Methods 0.000 description 2
- -1 hydrogen ions Chemical class 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 238000007036 catalytic synthesis reaction Methods 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- VQYJLACQFYZHCO-UHFFFAOYSA-N hydron;4-methoxyaniline;chloride Chemical compound [Cl-].COC1=CC=C([NH3+])C=C1 VQYJLACQFYZHCO-UHFFFAOYSA-N 0.000 description 1
- 238000001095 inductively coupled plasma mass spectrometry Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 239000004005 microsphere Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007363 ring formation reaction Methods 0.000 description 1
- 238000007151 ring opening polymerisation reaction Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000003335 steric effect Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
- 150000003752 zinc compounds Chemical class 0.000 description 1
- CRUISIDZTHMGJT-UHFFFAOYSA-L zinc;dichloride;hydrochloride Chemical compound Cl.[Cl-].[Cl-].[Zn+2] CRUISIDZTHMGJT-UHFFFAOYSA-L 0.000 description 1
Images
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
- B01J31/06—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides containing polymers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/26—Catalysts comprising hydrides, coordination complexes or organic compounds containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D319/00—Heterocyclic compounds containing six-membered rings having two oxygen atoms as the only ring hetero atoms
- C07D319/10—1,4-Dioxanes; Hydrogenated 1,4-dioxanes
- C07D319/12—1,4-Dioxanes; Hydrogenated 1,4-dioxanes not condensed with other rings
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Catalysts (AREA)
Abstract
The invention relates to the technical field of organic synthesis, in particular to a polyaniline-loaded zinc catalyst, a preparation method thereof and a lactide synthesis method. Mixing zinc salt and substituted or unsubstituted aniline in an acid aqueous solution according to a certain using amount, oxidizing and standing for more than 20 hours, neutralizing with alkali to generate a polyaniline-loaded zinc catalyst, and then carrying out solid-liquid separation and drying post-treatment to obtain the finished catalyst. The preparation method of the catalyst is simple, the conditions are mild, and the production cost can be effectively reduced; the low-toxicity and low-price zinc is selected as an active metal, and the polymerization degree of polyaniline and the zinc loading capacity in a finished catalyst product are maintained in a reasonable range by using a certain amount of zinc salt and substituted or unsubstituted aniline, so that the catalyst is particularly suitable for preparing lactide with high yield and high optical purity by catalysis.
Description
Technical Field
The invention relates to the technical field of organic synthesis, in particular to a polyaniline-loaded zinc catalyst and a preparation method and application thereof.
Background
Polylactic acid (PLA) is a novel biodegradable material, can be completely degraded by microorganisms in nature after being used, finally generates carbon dioxide and water, does not pollute the environment, is a well-known environment-friendly material, has good tensile strength, extensibility and air permeability, and has wide application prospect in the fields of disposable products and biomedicine.
At present, the synthetic routes of polylactic acid are generally divided into two routes, one is to directly polymerize lactic acid, and the lactic acid is polymerized into the polylactic acid with a certain molecular weight under the action of a specific catalyst, although the process is simple, the method is not easy to obtain the high molecular weight polylactic acid with excellent mechanical property; the other is formed by ring-opening polymerization of lactide, which can more easily obtain high molecular weight polylactic acid, and therefore, the synthesis process of lactide directly determines the quality of polylactic acid. The traditional lactide synthesis method is generally synthesized by the high-temperature cracking cyclization reaction of the low-polymer lactic acid, and has the problems of high energy consumption, low yield, insufficient purity and the like, which are important reasons for causing the overhigh production cost of the polylactic acid; therefore, how to solve these problems and synthesize lactide with high optical purity within an acceptable cost range lays a foundation for further producing high-performance polylactic acid materials, and is a key technical problem to be solved in the field.
Disclosure of Invention
Therefore, a polyaniline-supported zinc catalyst and a preparation method thereof are needed, wherein the polyaniline-supported zinc catalyst adopts cheap zinc salt as a raw material, is simple in preparation method, can greatly reduce the cost, can be used for preparing lactide with high optical purity in a catalytic manner, is high in reaction yield, and has a good application prospect.
In one aspect of the present invention, a preparation method of a polyaniline-supported zinc catalyst is provided, which comprises the following steps:
mixing zinc salt, substituted or unsubstituted aniline and an aqueous solution of acid to prepare a mixed solution; adding an oxidant into the mixed solution to prepare an oxidizing solution, and standing the oxidizing solution for more than 20 hours; adding an alkali aqueous solution into the oxidation solution after standing, separating out a precipitate, carrying out solid-liquid separation, collecting a solid phase, and drying;
the ratio of the zinc salt to the substituted or unsubstituted aniline is 1 (20-150).
In some embodiments, the method of mixing the zinc salt, the substituted or unsubstituted aniline, and the aqueous acid solution is:
dissolving the zinc salt in an aqueous solution of an acid to obtain a zinc salt solution; dissolving the substituted or unsubstituted aniline in another aqueous acid solution to obtain a substituted or unsubstituted aniline solution; mixing the zinc salt solution with the substituted or unsubstituted aniline solution to prepare the mixed solution;
the volume ratio of the zinc salt solution to the substituted or unsubstituted aniline solution is 1 (2-6).
In some embodiments, the concentration of the zinc salt solution is from 0.04mol/L to 0.1 mol/L; and/or
The concentration of the substituted or unsubstituted aniline solution is 0.8 mol/L-1.2 mol/L.
In some embodiments, the zinc salt is one or more of zinc chloride, zinc sulfate, zinc nitrate, and zinc acetate; and/or
The substituted or unsubstituted aniline is one or more of p-anisidine, p-methylaniline, p-ethylaniline, 2-methoxy-p-phenylenediamine, 2-ethoxy-p-phenylenediamine, 2-isopropoxy-p-phenylenediamine, aniline, p-fluoroaniline and 2-fluoroaniline; and/or
The acid aqueous solution is one or more of hydrochloric acid aqueous solution, sulfuric acid aqueous solution, nitric acid aqueous solution and acetic acid aqueous solution.
In some embodiments, the oxidizing agent is aqueous hydrogen peroxide and/or oxygen; and/or
The alkali aqueous solution is one or more of a lithium hydroxide aqueous solution, a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution.
In some embodiments, the temperature of the drying is 60 ℃ to 80 ℃; and/or
The concentration of the acid water solution is 0.8-1.2 mol/L; and/or
The concentration of the alkali aqueous solution is 0.8 mol/L-1.2 mol/L.
In some embodiments, a method of preparing a polyaniline-supported zinc catalyst comprises the steps of:
mixing a hydrochloric acid solution of zinc chloride with a hydrochloric acid solution of p-anisidine according to a volume ratio of 1 (2-6) to obtain a mixed solution; adding a hydrogen peroxide aqueous solution with the same volume as the hydrochloric acid solution of the zinc chloride into the mixed solution to prepare an oxidizing solution, and standing the oxidizing solution for more than 24 hours; adding an alkali aqueous solution into the oxidation solution after standing until no new precipitate is separated out, performing solid-liquid separation to retain a solid phase, and drying at 70 ℃;
the concentration of the hydrochloric acid solution of zinc chloride is 0.06-0.08 mol/L, the concentration of the hydrochloric acid solution of p-anisidine is 1mol/L, and the mass percentage concentration of the aqueous hydrogen peroxide solution is 30%.
In another aspect of the present invention, a polyaniline-supported zinc catalyst is provided, which is prepared by the preparation method according to any one of the foregoing embodiments.
In some embodiments, the polyaniline supported zinc catalyst has a zinc element loading of 9.5 wt% to 11 wt%, and the zinc element is present in the form of zinc oxide.
In another aspect of the present invention, there is also provided an application of the polyaniline-supported zinc catalyst prepared by the preparation method according to any one of the foregoing embodiments in lactide synthesis.
Mixing zinc salt and substituted or unsubstituted aniline in an acid aqueous solution according to a certain using amount, oxidizing and standing for more than 20 hours, neutralizing with alkali to generate a polyaniline-loaded zinc catalyst, and then carrying out solid-liquid separation and drying post-treatment to obtain the finished catalyst. The preparation method of the catalyst is simple, the conditions are mild, and the production cost can be effectively reduced; the low-toxicity and low-price zinc is selected as an active metal, and the polymerization degree of polyaniline and the zinc loading capacity in a finished catalyst product are maintained in a reasonable range by using a certain amount of zinc salt and substituted or unsubstituted aniline, so that the catalyst is particularly suitable for preparing lactide with high yield and high optical purity by catalysis.
Drawings
FIG. 1 is a Scanning Electron Microscope (SEM) image of the catalyst prepared in example 1;
FIG. 2 is a Transmission Electron Microscope (TEM) image (50nm) of the catalyst prepared in example 1;
FIG. 3 is a Transmission Electron Microscope (TEM) image (5nm) of the catalyst prepared in example 1;
FIG. 4 is a high resolution transmission electron microscope (HR-TEM) image of the catalyst prepared in example 1;
FIG. 5 is an electron diffraction pattern of zinc oxide crystals in the catalyst obtained in example 1;
FIG. 6 is an energy dispersive X-ray (EDX) spectrum of the catalyst prepared in example 1.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise. In the description of the present invention, "a plurality" means at least one, e.g., one, two, etc., unless specifically limited otherwise.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In the present invention, the technical features described in the open type include a closed technical solution composed of the listed features, and also include an open technical solution including the listed features.
In the present invention, the numerical intervals are regarded as continuous, and include the minimum and maximum values of the range and each value between the minimum and maximum values, unless otherwise specified. Further, when a range refers to an integer, each integer between the minimum and maximum values of the range is included. Further, when multiple range-describing features or characteristics are provided, the ranges may be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein.
The percentage contents referred to in the present invention mean, unless otherwise specified, mass percentages for solid-liquid mixing and solid-solid phase mixing, and volume percentages for liquid-liquid phase mixing.
The percentage concentrations referred to in the present invention refer to the final concentrations unless otherwise specified. The final concentration refers to the ratio of the additive component in the system to which the component is added.
The temperature parameter in the present invention is not particularly limited, and may be a constant temperature treatment or a treatment within a certain temperature range. The constant temperature process allows the temperature to fluctuate within the accuracy of the instrument control.
In one aspect of the present invention, a preparation method of a polyaniline-supported zinc catalyst is provided, which comprises the following steps:
mixing zinc salt, substituted or unsubstituted aniline and an aqueous solution of acid to prepare a mixed solution; adding an oxidant into the mixed solution to prepare an oxidizing solution, and standing the oxidizing solution for more than 20 hours; adding an alkali aqueous solution into the oxidation solution after standing, separating out a precipitate, carrying out solid-liquid separation, collecting a solid phase, and drying;
the ratio of the zinc salt to the substituted or unsubstituted aniline is 1 (20-150).
Mixing zinc salt and substituted or unsubstituted aniline in an acid aqueous solution according to a certain using amount, oxidizing to polymerize the substituted or unsubstituted aniline, standing for more than 20 hours, neutralizing with alkali to generate black precipitate, wherein the precipitate is the polyaniline-loaded zinc catalyst, and then carrying out solid-liquid separation and drying post-treatment to obtain the finished catalyst. The preparation method of the catalyst is simple, the conditions are mild, and the production cost can be effectively reduced; the low-toxicity and low-price zinc is selected as an active metal, and the polymerization degree of polyaniline and the zinc loading capacity in a finished catalyst product are maintained in a reasonable range by using a certain amount of zinc salt and substituted or unsubstituted aniline, so that the catalyst is particularly suitable for preparing lactide with high yield and high optical purity by catalysis.
In some embodiments, the ratio of the amount of zinc salt to substituted or unsubstituted aniline can be, for example, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, 1:65, 1:70, 1:75, 1:80, 1:85, 1:90, 1:95, 1:100, 1:105, 1:110, 1:115, 1:120, 1:125, 1:130, 1:135, 1:140, 1:145, and can also be, for example, 3:200, 7: 400.
In some embodiments, the oxidizing solution is allowed to stand for more than 24 hours. The oxidation liquid is kept stand to ensure that the oxidation polymerization reaction is thorough, and the zinc can be well loaded on the polyaniline carrier.
It is understood that the amount of the aqueous alkali solution added to the oxidation liquid after standing is such that the precipitate is completely precipitated, that is, the addition of the aqueous alkali solution is stopped until no new precipitate is formed in the system.
In some embodiments, the method of mixing the aqueous solution of the zinc salt, the substituted or unsubstituted aniline, and the acid is:
dissolving zinc salt in an aqueous solution of an acid to obtain a zinc salt solution; dissolving substituted or unsubstituted aniline in another aqueous acid solution to obtain a substituted or unsubstituted aniline solution; mixing a zinc salt solution with a substituted or unsubstituted aniline solution to prepare a mixed solution;
the volume ratio of the zinc salt solution to the substituted or unsubstituted aniline solution is 1 (2-6). Alternatively, the volume ratio of the zinc salt solution to the substituted or unsubstituted aniline solution may be, for example, 1:3, 1:4, or 1: 5.
The zinc salt and the substituted or unsubstituted aniline are respectively dissolved in the aqueous solution of acid, so that the zinc salt and the substituted or unsubstituted aniline can be better dispersed, and the loaded zinc catalyst with more uniform distribution is prepared; the respective solutions are mixed according to a certain volume ratio, so that the concentration of the zinc element loaded by the polyaniline carrier in unit volume is in a proper range, the synthesis reaction of the lactide can be catalyzed more efficiently, and the lactide with higher purity can be obtained.
In some embodiments, the concentration of the zinc salt solution is from 0.04mol/L to 0.1 mol/L. Alternatively, the concentration of the zinc salt solution may be, for example, 0.06mol/L to 0.08mol/L, or, for example, 0.045mol/L, 0.05mol/L, 0.055mol/L, 0.06mol/L, 0.065mol/L, 0.07mol/L, 0.075mol/L, 0.08mol/L, 0.085mol/L, 0.09mol/L, or 0.095 mol/L. The proper concentration of zinc salt is more beneficial to fully loading zinc on the polyaniline carrier and improving the catalytic activity.
In some embodiments, the concentration of the substituted or unsubstituted aniline solution is between 0.8mol/L and 1.2 mol/L. Alternatively, the concentration of the substituted or unsubstituted aniline solution may be, for example, 0.9mol/L, 1.0mol/L, or 1.1 mol/L. The polyaniline with more proper polymerization degree and crosslinking density can be obtained by proper concentration of the substituted or unsubstituted aniline solution, so that zinc can be better loaded on the polyaniline, and the catalytic activity of the catalyst is further improved.
In some embodiments, the zinc salt is one or more of zinc chloride, zinc sulfate, zinc nitrate, and zinc acetate.
In some embodiments, the substituted or unsubstituted aniline is one or more of p-anisidine, p-methylaniline, p-ethylaniline, 2-methoxy-p-phenylenediamine, 2-ethoxy-p-phenylenediamine, 2-isopropoxy-p-phenylenediamine, aniline, p-fluoroaniline, and 2-fluoroaniline. Preferably, the substituted or unsubstituted aniline is one or more of p-anisidine, p-methylaniline, p-ethylaniline and 2-isopropoxy p-phenylenediamine. Further preferably, the substituted or unsubstituted aniline is p-anisidine. The electron-rich substituted or unsubstituted aniline can improve the electron cloud density of nitrogen on the polymer carrier, so that the coordination of the nitrogen and zinc is stronger, and the catalytic activity is improved. In addition, steric effects will also affect the coordination of the polymeric support to the zinc. Therefore, the p-anisidine which simultaneously satisfies the two conditions can obviously improve the yield of the catalytic reaction and the optical purity of the product simultaneously.
In some embodiments, the aqueous acid solution is one or more of aqueous hydrochloric acid, aqueous sulfuric acid, aqueous nitric acid, and aqueous acetic acid. Preferably, the aqueous acid solution and the zinc salt have the same anion, so that the system is more stable and uniform, and the catalyst with better performance is prepared.
In some embodiments, the oxidizing agent is aqueous hydrogen peroxide and/or oxygen. The aqueous hydrogen peroxide solution and the oxygen are clean and pollution-free oxidants, and other byproducts which influence a reaction system or cause environmental pollution cannot be generated after oxidation.
In some embodiments, the aqueous hydrogen peroxide solution has a concentration of 20% to 30% by weight. Preferably a commercially available 30% aqueous hydrogen peroxide solution.
In some embodiments, the aqueous base is one or more of an aqueous lithium hydroxide solution, an aqueous sodium hydroxide solution, and an aqueous potassium hydroxide solution.
In some embodiments, the temperature of drying is from 60 ℃ to 80 ℃. Preferably, the temperature of drying is 70 ℃. The proper drying temperature can make the catalyst be fully dried, and its structure can not be damaged.
In some embodiments, the concentration of the aqueous acid solution is between 0.8mol/L and 1.2 mol/L. Preferably, the concentration of the aqueous acid solution is 1 mol/L. It is understood that the concentration of the aqueous acid solution herein refers to the concentration of hydrogen ions.
In some embodiments, the concentration of the aqueous base solution is 0.8mol/L to 1.2 mol/L. Preferably, the concentration of the aqueous solution of the base is 1 mol/L. It is understood that the concentration of the aqueous alkali solution herein refers to the concentration of hydroxide ions.
In some embodiments, a method of preparing a polyaniline-supported zinc catalyst comprises the steps of:
mixing a hydrochloric acid solution of zinc chloride and a hydrochloric acid solution of p-anisidine according to a volume ratio of 1 (2-6) to obtain a mixed solution; adding hydrogen peroxide aqueous solution with the same volume as hydrochloric acid solution of zinc chloride into the mixed solution to prepare oxidation solution, and standing the oxidation solution for more than 24 hours; adding an alkali aqueous solution into the oxidation solution after standing until no new precipitate is separated out, performing solid-liquid separation to retain a solid phase, and drying at 70 ℃;
wherein the concentration of the hydrochloric acid solution of zinc chloride is 0.06 mol/L-0.08 mol/L, the concentration of the hydrochloric acid solution of p-anisidine is 1mol/L, and the mass percentage concentration of the aqueous solution of hydrogen peroxide is 30%.
In another aspect of the present invention, a polyaniline-supported zinc catalyst is provided, which is prepared by the preparation method of any one of the foregoing embodiments.
In some embodiments, the polyaniline supported zinc catalyst has a zinc element loading of 9.5 wt% to 11 wt%, and the zinc element is present in the form of zinc oxide. Preferably, the loading amount of the zinc element is 9.8 wt% to 10.6 wt%. The loading of the zinc element can be obtained by an ICP-MS test.
Scanning Electron Microscope (SEM) images show (fig. 1) that the polyaniline-supported zinc catalyst is a polymeric microsphere of nanometer size; transmission Electron Microscope (TEM) images show (fig. 2, fig. 3) that the nano-scale black dots (i.e., zinc compounds) are uniformly distributed in the gray carrier (i.e., polyaniline); under a high-resolution transmission electron microscope (HR-TEM), a lattice plane having a spacing d (002) ═ 0.26nm was observed (fig. 4), indicating that in the polyaniline-supported zinc catalyst, zinc was present in the form of zinc oxide, and the presence of zinc oxide crystals was also reflected by its electron diffraction pattern (fig. 5); it can be proved by energy dispersive X-ray spectroscopy (EDX) that zinc oxide has been successfully supported on polyaniline carrier (fig. 6), and that the two are not present in a simple physical blend in the catalyst.
In another aspect of the present invention, there is also provided an application of the polyaniline-supported zinc catalyst prepared by the preparation method according to any one of the foregoing embodiments in lactide synthesis.
In some embodiments, the synthesis of lactide with polyaniline supported zinc catalyst comprises the steps of:
reacting lactic acid for 2-6 h at 145-155 ℃ and 350-370 mmHg to obtain oligomeric lactic acid; preferably, the reaction is carried out at 150 ℃ and 360mmHg for 4 h.
Adding polyaniline-loaded zinc catalyst with the mass of 0.1-0.3% of that of lactic acid into a reaction system, and reacting for 2-4 h at 215-225 ℃ under the condition of 5 mmHg-15 mmHg to prepare lactide; preferably, 0.2 percent of polyaniline-supported zinc catalyst based on the mass of lactic acid is added into the reaction system, and the reaction is carried out for 3 hours at the temperature of 220 ℃ and under the condition of 10 mmHg.
In some embodiments, the lactide is post-recrystallized using ethyl acetate.
The polyaniline-loaded zinc catalyst prepared by the invention can synthesize lactide with high optical purity at high yield, and the catalyst which is used once is used for catalyzing and synthesizing lactide again without special treatment after the reaction is finished, so that the yield is slightly reduced, but the optical purity of the product is basically kept unchanged; tests show that the polyaniline-loaded zinc catalyst can be used for at least 9 times, maintains the high catalytic performance of more than 70% of yield and more than 97% of optical purity, is a repeatable and durable catalyst, and has wide industrial application prospect.
The present invention will be described in further detail with reference to specific examples and comparative examples. Experimental parameters not described in the following specific examples are preferably referred to the guidelines given in the present application, and may be referred to experimental manuals in the art or other experimental methods known in the art, or to experimental conditions recommended by the manufacturer. It is understood that the following examples are specific to the apparatus and materials used, and in other embodiments, the present invention is not limited thereto, and may be, for example, not limited to the use of lactic acid.
Example 1
(1) Mixing a hydrochloric acid solution of zinc chloride (wherein the hydrochloric acid concentration is 1mol/L, and the zinc chloride concentration is 0.06mol/L) with a hydrochloric acid solution of p-anisidine (wherein the hydrochloric acid concentration is 1mol/L, and the p-anisidine concentration is 1mol/L) according to a volume ratio of 1:4, adding an aqueous hydrogen peroxide solution (30% mass concentration) with the same volume as the hydrochloric acid solution of zinc chloride, stirring uniformly under air, standing for 24 hours, neutralizing with a 1mol/L aqueous sodium hydroxide solution until no new precipitate is generated, centrifuging, and drying the precipitate at 70 ℃ in vacuum to obtain the poly-p-anisidine supported zinc catalyst;
(2) adding 50g of L-lactic acid into a container, reacting for 4 hours at 150 ℃ and 360mmHg to obtain oligomeric lactic acid, then adding 100mg of the poly-p-anisidine loaded zinc catalyst prepared in the step (1) into the reaction system, reacting for 3 hours at 220 ℃ and 10mmHg, distilling out lactide, and recrystallizing with ethyl acetate.
Examples 2 to 9
The method is basically the same as that of example 1, except that the substituted or unsubstituted anilines used in examples 2 to 9 are respectively: 2-isopropoxy p-phenylenediamine, p-methylaniline, p-ethylaniline, 2-methoxy p-phenylenediamine, 2-ethoxy p-phenylenediamine, aniline, p-fluoroaniline and 2-fluoroaniline.
Examples 10 to 15
The method is basically the same as that of example 1, except that the concentrations of the zinc chloride zincate solutions in examples 10 to 15 are respectively 0.04mol/L, 0.05mol/L, 0.07mol/L, 0.08mol/L, 0.09mol/L and 0.1mol/L in this order.
Examples 16 to 19
The method is basically the same as the method in the embodiment 1, except that the volume ratios of the zinc chloride hydrochloric acid solution and the p-methoxyaniline hydrochloric acid solution in the embodiments 16-19 are respectively 1:2, 1:3, 1:5 and 1: 6.
Comparative example 1
The same as example 1 except that in comparative example 1, p-phenylenediamine was used.
Comparative examples 2 to 4
The method is basically the same as that of example 1, except that the concentrations of the zinc chloride zincate solutions in comparative examples 2 to 4 are 0.01mol/L, 0.02mol/L and 0.03mol/L respectively in this order.
Comparative example 5
Substantially the same as in example 1 except that a polymethoxyaniline was prepared by the procedure of example 1 without adding a hydrochloric acid solution of zinc chloride, and the obtained polymethoxyaniline was physically blended with zinc oxide while maintaining the same amount of zinc oxide as the loading amount of zinc oxide in example 1.
Characterization test:
the yields of lactide produced in the examples and comparative examples were calculated, and the recrystallized lactide product was dissolved in toluene and compared with a standard sample having an optical purity of more than 99.9% to measure the optical purity, and the results are shown in tables 1 to 3:
TABLE 1
TABLE 2
TABLE 3
As can be seen from tables 1 to 3, the catalysts prepared in the examples of the present invention have high yield and very high optical purity when used for lactide synthesis. Compared with the catalyst prepared from substituted aniline containing electron-donating groups, the catalyst prepared from substituted aniline containing electron-donating groups has better catalytic activity; although the amino group is also an electron-donating group, the p-phenylenediamine contains two amino groups, and two coordination sites are formed, and the two coordination sites can interfere with each other, so that coordination with zinc is influenced, and in the p-phenylenediamine containing an electron-donating substituent, the nitrogen electron cloud density at the meta position of the substituent is higher, the coordination with zinc is better, and the p-phenylenediamine has certain selectivity compared with the p-phenylenediamine without other substituents, so that the catalytic activity is improved to a certain extent, but the electron effect is still not as good as that of electron-donating substituted aniline, and it can be seen that although the electron effect has an influence on the performance of the catalyst, the electron effect is not the only influencing factor, and factors such as the number of coordination sites, selectivity, steric hindrance, the concentration of a zinc salt solution, the volume ratio of the zinc salt solution to the aniline solution and the like, which influence the coordination of polyaniline and zinc oxide, also participate in determining the performance of the finally prepared catalyst. Therefore, the preparation of a catalyst with high catalytic activity and high selectivity is the result of a combination of factors.
In comparative example 5, the poly (p-anisidine) and the zinc oxide are physically blended, and no chemical bond interaction exists between the poly (p-anisidine) and the zinc oxide, so that the reaction yield and the optical purity of the product are reduced during the catalytic synthesis of the lactide, particularly the reaction yield is greatly reduced, which proves that the coordination effect of the polyaniline carrier and the zinc oxide has great influence on the catalytic activity of the catalyst.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims, and the description and the drawings can be used for explaining the contents of the claims.
Claims (10)
1. A preparation method of a polyaniline loaded zinc catalyst is characterized by comprising the following steps:
mixing zinc salt, substituted or unsubstituted aniline and an aqueous solution of acid to prepare a mixed solution; adding an oxidant into the mixed solution to prepare an oxidizing solution, and standing the oxidizing solution for more than 20 hours; adding an alkali aqueous solution into the oxidation solution after standing, separating out a precipitate, carrying out solid-liquid separation, collecting a solid phase, and drying;
the ratio of the zinc salt to the substituted or unsubstituted aniline is 1 (20-150).
2. The method of claim 1, wherein the mixing of the zinc salt, the substituted or unsubstituted aniline, and the aqueous acid solution comprises:
dissolving the zinc salt in an aqueous solution of an acid to obtain a zinc salt solution; dissolving the substituted or unsubstituted aniline in another aqueous acid solution to obtain a substituted or unsubstituted aniline solution; mixing the zinc salt solution with the substituted or unsubstituted aniline solution to prepare the mixed solution;
the volume ratio of the zinc salt solution to the substituted or unsubstituted aniline solution is 1 (2-6).
3. The preparation method according to claim 2, wherein the concentration of the zinc salt solution is 0.04mol/L to 0.1 mol/L; and/or
The concentration of the substituted or unsubstituted aniline solution is 0.8 mol/L-1.2 mol/L.
4. The preparation method according to claim 1, wherein the zinc salt is one or more of zinc chloride, zinc sulfate, zinc nitrate and zinc acetate; and/or
The substituted or unsubstituted aniline is one or more of p-anisidine, p-methylaniline, p-ethylaniline, 2-methoxy-p-phenylenediamine, 2-ethoxy-p-phenylenediamine, 2-isopropoxy-p-phenylenediamine, aniline, p-fluoroaniline and 2-fluoroaniline; and/or
The acid aqueous solution is one or more of hydrochloric acid aqueous solution, sulfuric acid aqueous solution, nitric acid aqueous solution and acetic acid aqueous solution.
5. The production method according to any one of claims 1 to 4, wherein the oxidizing agent is an aqueous hydrogen peroxide solution and/or oxygen; and/or
The alkali aqueous solution is one or more of a lithium hydroxide aqueous solution, a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution.
6. The method according to any one of claims 1 to 4, wherein the drying temperature is 60 ℃ to 80 ℃; and/or
The concentration of the acid water solution is 0.8-1.2 mol/L; and/or
The concentration of the alkali aqueous solution is 0.8 mol/L-1.2 mol/L.
7. The method of claim 1, comprising the steps of:
mixing a hydrochloric acid solution of zinc chloride with a hydrochloric acid solution of p-anisidine according to a volume ratio of 1 (2-6) to obtain a mixed solution; adding a hydrogen peroxide aqueous solution with the same volume as the hydrochloric acid solution of the zinc chloride into the mixed solution to prepare an oxidizing solution, and standing the oxidizing solution for more than 24 hours; adding an alkali aqueous solution into the oxidation solution after standing until no new precipitate is separated out, performing solid-liquid separation to retain a solid phase, and drying at 70 ℃;
the concentration of the hydrochloric acid solution of zinc chloride is 0.06-0.08 mol/L, the concentration of the hydrochloric acid solution of p-anisidine is 1mol/L, and the mass percentage concentration of the aqueous hydrogen peroxide solution is 30%.
8. A polyaniline-supported zinc catalyst, which is characterized by being prepared by the preparation method of any one of claims 1 to 7.
9. The polyaniline supported zinc catalyst of claim 8, wherein the polyaniline supported zinc catalyst has a zinc element loading of 9.5 wt% to 11 wt%, and the zinc element is present in the form of zinc oxide.
10. The application of the polyaniline-loaded zinc catalyst prepared by the preparation method of any one of claims 1 to 7 in lactide synthesis.
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| CN113582965A (en) * | 2021-08-23 | 2021-11-02 | 扬州惠通科技股份有限公司 | Method for preparing high-purity lactide based on catalytic cracking of organic guanidine complex |
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| DE1280838B (en) * | 1964-12-28 | 1968-10-24 | Ethicon Inc | Process for purifying lactides |
| CN102863791A (en) * | 2012-07-16 | 2013-01-09 | 云南大学 | Preparation method of zinc-oxide/polyaniline composite hollow microsphere |
| CN109824891A (en) * | 2019-02-27 | 2019-05-31 | 扬州大学广陵学院 | A kind of synthetic method of polyaniline |
| CN113582965A (en) * | 2021-08-23 | 2021-11-02 | 扬州惠通科技股份有限公司 | Method for preparing high-purity lactide based on catalytic cracking of organic guanidine complex |
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| CN115677648A (en) * | 2022-10-31 | 2023-02-03 | 扬州大学 | Synthesis method of lactide with high optical purity |
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