CN115069241A - Phosphine-assisted patch modulation loaded gold nanocluster, preparation method and catalytic application - Google Patents
Phosphine-assisted patch modulation loaded gold nanocluster, preparation method and catalytic application Download PDFInfo
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- 239000010931 gold Substances 0.000 title claims abstract description 77
- 229910052737 gold Inorganic materials 0.000 title claims abstract description 71
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims abstract description 68
- XYFCBTPGUUZFHI-UHFFFAOYSA-N Phosphine Chemical compound P XYFCBTPGUUZFHI-UHFFFAOYSA-N 0.000 title claims abstract description 24
- 229910000073 phosphorus hydride Inorganic materials 0.000 title claims abstract description 12
- 238000002360 preparation method Methods 0.000 title claims abstract description 12
- 230000003197 catalytic effect Effects 0.000 title abstract description 20
- 229920002873 Polyethylenimine Polymers 0.000 claims abstract description 20
- 239000011148 porous material Substances 0.000 claims abstract description 11
- 238000000034 method Methods 0.000 claims abstract description 10
- 239000004005 microsphere Substances 0.000 claims description 24
- MYRTYDVEIRVNKP-UHFFFAOYSA-N 1,2-Divinylbenzene Chemical compound C=CC1=CC=CC=C1C=C MYRTYDVEIRVNKP-UHFFFAOYSA-N 0.000 claims description 10
- 229920000642 polymer Polymers 0.000 claims description 6
- VJJZJBUCDWKPLC-UHFFFAOYSA-N 3-methoxyapigenin Chemical compound O1C2=CC(O)=CC(O)=C2C(=O)C(OC)=C1C1=CC=C(O)C=C1 VJJZJBUCDWKPLC-UHFFFAOYSA-N 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 238000010531 catalytic reduction reaction Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- KCXMKQUNVWSEMD-UHFFFAOYSA-N benzyl chloride Chemical group ClCC1=CC=CC=C1 KCXMKQUNVWSEMD-UHFFFAOYSA-N 0.000 claims description 3
- 239000000758 substrate Substances 0.000 claims description 3
- 238000010558 suspension polymerization method Methods 0.000 claims description 3
- 125000001797 benzyl group Chemical group [H]C1=C([H])C([H])=C(C([H])=C1[H])C([H])([H])* 0.000 claims description 2
- 125000004803 chlorobenzyl group Chemical group 0.000 claims description 2
- 150000002500 ions Chemical class 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 239000000178 monomer Substances 0.000 claims description 2
- 238000004873 anchoring Methods 0.000 claims 1
- 150000003003 phosphines Chemical class 0.000 claims 1
- -1 gold ions Chemical class 0.000 abstract description 7
- 238000013508 migration Methods 0.000 abstract description 4
- 230000005012 migration Effects 0.000 abstract description 4
- PARWUHTVGZSQPD-UHFFFAOYSA-N phenylsilane Chemical compound [SiH3]C1=CC=CC=C1 PARWUHTVGZSQPD-UHFFFAOYSA-N 0.000 abstract description 4
- 125000002743 phosphorus functional group Chemical group 0.000 abstract description 3
- 238000011065 in-situ storage Methods 0.000 abstract description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 25
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 14
- 229910052757 nitrogen Inorganic materials 0.000 description 14
- 239000003054 catalyst Substances 0.000 description 9
- 239000003446 ligand Substances 0.000 description 8
- 239000000243 solution Substances 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 4
- ZUOUZKKEUPVFJK-UHFFFAOYSA-N diphenyl Chemical compound C1=CC=CC=C1C1=CC=CC=C1 ZUOUZKKEUPVFJK-UHFFFAOYSA-N 0.000 description 4
- 235000019441 ethanol Nutrition 0.000 description 4
- 239000002105 nanoparticle Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 239000012071 phase Substances 0.000 description 4
- 238000001228 spectrum Methods 0.000 description 4
- OZAIFHULBGXAKX-UHFFFAOYSA-N 2-(2-cyanopropan-2-yldiazenyl)-2-methylpropanenitrile Chemical compound N#CC(C)(C)N=NC(C)(C)C#N OZAIFHULBGXAKX-UHFFFAOYSA-N 0.000 description 3
- BTJIUGUIPKRLHP-UHFFFAOYSA-N 4-nitrophenol Chemical compound OC1=CC=C([N+]([O-])=O)C=C1 BTJIUGUIPKRLHP-UHFFFAOYSA-N 0.000 description 3
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 description 3
- 239000008346 aqueous phase Substances 0.000 description 3
- 239000008367 deionised water Substances 0.000 description 3
- 229910021641 deionized water Inorganic materials 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000011068 loading method Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229920000768 polyamine Polymers 0.000 description 3
- 238000006722 reduction reaction Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000004305 biphenyl Substances 0.000 description 2
- 235000010290 biphenyl Nutrition 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 238000007306 functionalization reaction Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- RPGWZZNNEUHDAQ-UHFFFAOYSA-N phenylphosphine Chemical compound PC1=CC=CC=C1 RPGWZZNNEUHDAQ-UHFFFAOYSA-N 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000001291 vacuum drying Methods 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- RSSDWSPWORHGIE-UHFFFAOYSA-N $l^{1}-phosphanylbenzene Chemical group [P]C1=CC=CC=C1 RSSDWSPWORHGIE-UHFFFAOYSA-N 0.000 description 1
- RBTBFTRPCNLSDE-UHFFFAOYSA-N 3,7-bis(dimethylamino)phenothiazin-5-ium Chemical compound C1=CC(N(C)C)=CC2=[S+]C3=CC(N(C)C)=CC=C3N=C21 RBTBFTRPCNLSDE-UHFFFAOYSA-N 0.000 description 1
- OZAIFHULBGXAKX-VAWYXSNFSA-N AIBN Substances N#CC(C)(C)\N=N\C(C)(C)C#N OZAIFHULBGXAKX-VAWYXSNFSA-N 0.000 description 1
- 238000004438 BET method Methods 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 238000000944 Soxhlet extraction Methods 0.000 description 1
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- 238000006887 Ullmann reaction Methods 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000005576 amination reaction Methods 0.000 description 1
- YCOXTKKNXUZSKD-UHFFFAOYSA-N as-o-xylenol Natural products CC1=CC=C(O)C=C1C YCOXTKKNXUZSKD-UHFFFAOYSA-N 0.000 description 1
- 229940073608 benzyl chloride Drugs 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- XGRJZXREYAXTGV-UHFFFAOYSA-N chlorodiphenylphosphine Chemical compound C=1C=CC=CC=1P(Cl)C1=CC=CC=C1 XGRJZXREYAXTGV-UHFFFAOYSA-N 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 239000000412 dendrimer Substances 0.000 description 1
- 229920000736 dendritic polymer Polymers 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- GPAYUJZHTULNBE-UHFFFAOYSA-N diphenylphosphine Chemical compound C=1C=CC=CC=1PC1=CC=CC=C1 GPAYUJZHTULNBE-UHFFFAOYSA-N 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- DOWCWUCBOQRQJE-UHFFFAOYSA-N ditert-butylphosphane;hydrochloride Chemical compound Cl.CC(C)(C)PC(C)(C)C DOWCWUCBOQRQJE-UHFFFAOYSA-N 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000002638 heterogeneous catalyst Substances 0.000 description 1
- 239000002815 homogeneous catalyst Substances 0.000 description 1
- 239000005457 ice water Substances 0.000 description 1
- SNHMUERNLJLMHN-UHFFFAOYSA-N iodobenzene Chemical compound IC1=CC=CC=C1 SNHMUERNLJLMHN-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 238000010907 mechanical stirring Methods 0.000 description 1
- 239000013335 mesoporous material Substances 0.000 description 1
- 239000012621 metal-organic framework Substances 0.000 description 1
- 229960000907 methylthioninium chloride Drugs 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 239000013384 organic framework Substances 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 239000003361 porogen Substances 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000012279 sodium borohydride Substances 0.000 description 1
- 229910000033 sodium borohydride Inorganic materials 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000000967 suction filtration Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/48—Silver or gold
- B01J23/52—Gold
-
- 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
- B01J31/069—Hybrid organic-inorganic polymers, e.g. silica derivatized with organic groups
-
- B01J35/23—
-
- B01J35/61—
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C213/00—Preparation of compounds containing amino and hydroxy, amino and etherified hydroxy or amino and esterified hydroxy groups bound to the same carbon skeleton
- C07C213/02—Preparation of compounds containing amino and hydroxy, amino and etherified hydroxy or amino and esterified hydroxy groups bound to the same carbon skeleton by reactions involving the formation of amino groups from compounds containing hydroxy groups or etherified or esterified hydroxy groups
Abstract
The invention relates to a phosphine-assisted patch modulation loaded gold nanocluster, a preparation method and a catalytic application thereof. During preparation, the spherical low molecular weight branched polyethyleneimine is anchored on the pore surface of the carrier and distributed on the pore surface in a patch shape; covalently introducing an amount of phosphine to the patch and allowing it to form a complex with gold ions (au (i)); au (I) in the complex is reduced by a gas such as phenylsilane to generate gold nanoclusters in situ. The method sufficiently inhibits the migration of gold species, so that the size of gold nanoclusters formed on the patch can be determined to a large extent by the number of phosphorus groups introduced in advance. The gold nanoclusters exhibit high catalytic activity and are easy to recycle.
Description
Technical Field
The invention belongs to the field of catalytic materials, and particularly relates to preparation of a supported gold nanocluster prepared by utilizing a nanoscale patch and phosphine introduced into the patch and application of the supported gold nanocluster in catalytic reduction.
Background
Gold atoms on the surface of the gold particles can catalyze various chemical reactions, and the smaller the particles are, the higher the catalytic efficiency is, so that the gold nanoclusters with ultrahigh specific surface area are becoming one of important research and development points. The gold nanoclusters are ultra-small particles with the size of 0.1-2.3 nm. The atomic catalytic efficiency of the gold nanoclusters is very outstanding due to the high surface atomic ratio. The gold nanoparticles are more stable and easier to prepare, and therefore the gold nanoparticles play an important role in the field of noble metal catalysts. However, gold nanoclusters are generally difficult to obtain unless expensive templates such as dendrimers, carbon organic frameworks, metal organic frameworks, etc. are used or in the presence of large amounts of strong ligands. Meanwhile, the strong ligand often causes the catalytic spectrum of gold to be narrowed, so that the application range of the gold is limited, and meanwhile, the catalytic activity is usually reduced. Thus, the development of mild ligand-passivated gold nanoclusters is of practical significance.
To facilitate the recovery of catalysts on a nanometer scale, the catalysts are often supported on porous supports of much larger size and having a high specific surface. This is beneficial to the repeated utilization of the catalyst and the quality improvement of the product. Currently, most catalysts in industry are heterogeneous catalysts, which can improve separation efficiency and product quality.
Preparing gold nanoclusters that are uniform and extremely small in size on a support remains a challenge. There are many challenges to obtaining small and uniform sized gold nanoclusters due to the heterogeneous nature and complexity of the manufacturing kinetics, and the gold particles typically obtained are not only too large in size, but also non-uniform in size distribution. A patch modulation scheme has been proposed in the closest patents (CN 113070100B, 2022). The spherical macromolecular weak ligand (branched polyethyleneimine) is anchored on the carrier in a patch form, and the patch can inhibit migration of gold atoms in the preparation process to a certain extent, so that smaller and more uniform gold nanoparticles are obtained; if a certain amount of ligand of moderate strength is further introduced on the ligand patch, the result is gold nanoclusters of much smaller and more uniform size under similar conditions. This is probably due to the presence of stronger ligands making the gold atoms easier to nucleate. This is an example of the preparation of highly catalytically active gold nanoclusters by the combination of ligands and patches. Clearly, this is different from the strong ligand-modulated gold nanoclusters, which are more narrow in catalytic spectrum and completely catalytically inactive for certain types of chemical reactions.
According to the calculation results, gold species migration in this scheme is still very severe, i.e. only about 4% of patches eventually grow gold nanoclusters, and most patches are empty, which indicates that the preparation of gold nanoclusters of smaller size is still difficult to achieve.
Disclosure of Invention
Aiming at the defects in the prior art, the invention mainly aims to design a new method to obtain the loaded gold nanoclusters with uniform size, wherein the size of the loaded gold nanoclusters is about 1 nanometer. The method of the invention uses the patch as a micro-reactor and avoids the substance exchange between the micro-reactors to the maximum extent.
A second object of the present invention is to prepare the microsphere-supported gold nanoclusters.
A third object of the present invention is to use the nanoclusters as a recyclable catalytic material.
In order to achieve the above purpose, the solution of the invention is as follows:
a preparation method of gold nanoclusters modulated by mesoporous polymer microspheres comprises the following steps:
(1) the mesoporous polymer microsphere with a large number of benzyl chloride functional groups on the surface of the pores is obtained by a suspension polymerization method.
(2) The branched polyethyleneimine is anchored on the surface of the microsphere pores by means of reaction with benzyl chloride.
(3) A quantity of organic phosphorus is chemically reacted onto the polyethyleneimine patch.
(4) Au (I) is added to form a complex with the phosphine.
(5) Reducing Au (I) ions with a gas in an inert environment to form supported gold nanoclusters.
Preferably, in the step (1), the polymerized monomers are 4-vinylbenzyl chloride and divinylbenzene, and the molar ratio of the 4-vinylbenzyl chloride to the divinylbenzene is 0.8-1.2: 1.
Preferably, in step (2), the molar charge of branched polyethyleneimine is 0.6-0.9 equivalent of benzyl.
Preferably, in step (2), the molecular weight of the branched polyethyleneimine is 600-2000 daltons, and the branching degree is 60 +/-5%.
Preferably, in step (3), 8 to 40 phosphorus groups are grafted per branched polyethyleneimine.
Preferably, in the step (4), the amount of au (i) to be added is (1 ± 0.5): 1 dose such as an administration.
Preferably, in the step (5), the reducing agent is a gas with a boiling point higher than room temperature, such as phenylsilane, and the gold ions are reduced at a proper temperature within several minutes to several hours.
The preparation method can be used for obtaining the ultra-small load gold nanoclusters.
The gold nanocluster catalytic material is used for catalytic reduction of various substrates.
Due to the adoption of the scheme, the invention has the beneficial effects that:
because the patches are isolated by the inert carrier and gold species (including gold ions and gold atoms) cannot migrate among the patches under the gas-phase reduction condition, the number of gold atoms of the gold nanoclusters formed on each patch is determined by the number of gold ions which are complexed in advance, so that the size of the gold nanoclusters can be conveniently controlled, and the catalyst with a high specific surface area is obtained.
Since phosphine is a ligand with medium strength and does not inhibit the catalytic activity of gold per se, the gold nanocluster prepared by the method has a wide catalytic chemical spectrum and high catalytic activity.
Because the carrier is large in size, the catalyst is easy to recycle.
Drawings
FIG. 1 is a nitrogen adsorption curve of mesoporous polymer microspheres.
Fig. 2 shows XPS of mesoporous supports loaded with gold species before (lower panel) and after (upper panel) reduction.
FIG. 3 is a time-evolution diagram of an ultraviolet/visible light spectrum of a supported gold nanocluster for catalyzing the reduction of 4-nitrophenol.
Detailed Description
The present invention will be further described with reference to the following examples.
During preparation, the spherical low molecular weight branched polyethyleneimine is anchored on the pore surface of the carrier and distributed on the pore surface in a patch shape; covalently introducing an amount of phosphine to the patch and allowing it to form a complex with gold ions (au (i)); au (I) in the complex is reduced by a gas such as phenylsilane to form gold nanoclusters in situ. The method sufficiently inhibits the migration of gold species, so that the size of gold nanoclusters formed on the patch can be determined to a large extent by the number of phosphorus groups introduced in advance. The gold nanoclusters exhibit high catalytic activity and are easy to recycle.
Examples are given below.
Example 1
Synthesis step of chlorobenzyl functionalized microspheres
The mesoporous polymer microspheres are synthesized by a suspension polymerization method (reference: Macromolecules 2006,39 and 627), and the pore-forming agent adopts a good solvent type so as to obtain small pore generation. Polyvinyl alcohol 1788(1g) was dissolved well in deionized water (200mL), to which was added sodium chloride (4g), methylene blue solution (0.1 wt.%, 4mL), to give an aqueous phase of the suspension. 4-vinylbenzyl chloride (13g,0.085mol), divinylbenzene (11g,0.085mol), azobisisobutyronitrile (AIBN, 0.1g) and a porogen toluene (24ml) were mixed as an oil phase. The oil phase was added dropwise to the aqueous phase with mechanical stirring at 350rpm and heated under nitrogen at 70 ℃ for 3 hours followed by heating to 80 ℃ for 2 hours. And (3) carrying out suction filtration to separate out microspheres, carrying out Soxhlet extraction for 12 hours by using acetone, and carrying out vacuum drying at 50 ℃ to obtain the mesoporous microspheres. The specific surface area is 490m determined by nitrogen adsorption method 2 (g), the average size of mesopores was 3.5nm (FIG. 1).
Amination step
Branched polyethyleneimine (molecular weight 2000 daltons, branching degree 60%, 1.77 g, 41mmol NH) is heated (60 ℃) under vacuum for half an hour to remove carbon dioxide which can be absorbed, then dissolved in ethanol, added with chlorobenzylated microspheres (15g, 49mmol Cl) into the solution, heated to 80 ℃ under the protection of nitrogen, stirred vigorously and refluxed for reaction for 6 hours. Filtering the product, respectively soaking and washing with 5% NaOH aqueous solution, deionized water and anhydrous ethanol for several times, and vacuum drying at 40 deg.CDrying to constant weight to obtain the aminated microsphere. Elemental analysis: c, 76.39%, N, 2.13%, H, 6.49%. The loading of PEI on the carrier was derived to be 1.52mmol NH/g (0.065g polyethyleneimine/g) based on nitrogen content. BET method determination shows that the specific surface area of the polyamine is reduced from 490 to 210m 2 This is due to the blocking of part of the pores by the branched polyethyleneimine.
According to theoretical calculations, when the dry branched polyethyleneimine (molecular weight 2000 daltons) is present as an idealized sphere, the corresponding diameter is 1.86 nm; the coverage of the polyamine on the surface of the support is 23% based on the specific surface area of the support at present. This means that the branched polyethyleneimine will be anchored in the form of a patch to the pore surface of the mesoporous material.
Phenylphosphine functionalization step
To a solution of 700. mu.L (about 5mmol) of triethylamine in chloroform (20mL) in an ice-water bath under nitrogen was added diphenyl phosphine chloride (272. mu.L, 1.52mmol,0.334g) by a degassing syringe and 2g (3.04mmol NH) of aminated microspheres with vigorous stirring. Gradually rising to room temperature and reacting for 24 hours under the protection of a nitrogen ball. Filtering and separating the microspheres, respectively soaking and washing the microspheres for a plurality of times by using a KOH/ethanol solution, deionized water and absolute ethyl alcohol, drying the microspheres in a drying oven at the temperature of 40 ℃ to constant weight, and storing the microspheres in nitrogen. The product was ground and tested by XPS to determine the phosphorus content by XPS, which calculated that 25% of the amino units had been phosphorylated, i.e. 11.6 phenylphosphorus groups (0.38mmol/g) were attached to each polyamine patch.
Gold ion loading step
To a solution of Au (I) Cl (1.38mmol, prepared according to J Amer Chem Soc, 2013, 135, 3550) in ethanol (15mL) was added phenylphosphine functionalized microspheres (5 g). Stirring was continued for 2h at 40 ℃. The solid was separated and sequentially washed with ethanol and chloroform. XPS detected the binding energy of gold species therein (figure 2).
Gold nanocluster generation step
The mesoporous microspheres (2g) loaded with the monovalent gold complex were placed in a teflon bag and suspended in a glass bottle, the air in the bottle was replaced with nitrogen, and then phenylsilane liquid (2mL) was added to the bottom of the bottle. Heating at 110 deg.C for 1h under nitrogen ball seal. After cooling, the mixture was stored in nitrogen. XPS testing was performed to observe the binding energy of gold (figure 2). The theoretical loading of gold is 0.276mmol/g.
The binding energy of the reduced gold is reduced compared with that of univalent gold, and is respectively 88.1 eV and 84.4 eV. This binding energy is still high relative to typical gold nanoparticles, probably due to the small size of the gold nanoclusters. Failure to detect a signal with a transmission electron microscope should also be due to the gold nanoclusters being too small in size.
Example 2
In example 1, the catalyst was prepared in the same manner by using di-tert-butylphosphine chloride instead of diphenylphosphine.
Example 3 (catalytic application)
An aqueous solution (100mL) containing 4-nitrophenol (0.06mM) and sodium borohydride (6mM) was purged with nitrogen for 15 minutes, and then gold nanocluster-loaded microspheres (1mg) were put into the solution and stirred (600 rpm). The solution changed from red to colorless in 10 minutes, indicating that the 4-nitrophenol had been fully reduced (FIG. 3). The microspheres were filtered off and used in a second catalytic reduction, which still reduced the yellow substrate to a colorless product within 10 minutes. TOF was 1250/h. This value is close to that of a homogeneous catalyst, indicating that the atomic catalytic efficiency of gold is very high.
Example 4
In example 1, the molecules of polyethyleneimine are reduced to 600 daltons and phosphine functionalization is performed twice, otherwise conditions are referenced to example 1, resulting in gold nanoclusters. From the viewpoint of water absorption capacity, the hydrophilicity of pores is lowered, and the catalytic microspheres float on the water layer and are not suitable as an aqueous phase catalyst. But can be used for catalyzing the oil phase Ullmann reaction. The specific operation is that iodobenzene (1mmol) and potassium carbonate (3mmol) are put into dimethylformamide (5mL), nitrogen is introduced, catalytic microspheres (0.1g) are put into the mixture, and the mixture is heated at 120 ℃ for 24 hours. The liquid phase was measured by gas chromatography using biphenyl as a standard, giving a biphenyl yield of 50%.
Claims (8)
1. A preparation method for preparing gold nanoclusters by using patch-assisted mesoporous polymer microspheres is characterized by comprising the following steps:
(1) obtaining mesoporous polymer microspheres with benzyl chloride functional groups with certain density on the surfaces of pores by a suspension polymerization method;
(2) anchoring branched polyethyleneimine to the surface of a microsphere hole in a manner of reacting with chlorobenzyl to form a patch;
(3) a certain amount of organic phosphine is connected to polyethylene imine through chemical reaction;
(4) adding Au (I) to form a complex with the phosphine;
(5) reducing Au (I) ions in the complex by gas in an inert environment to form the supported gold nanoclusters.
2. The method according to claim 1, wherein in the step (1), the polymerized monomers are 4-vinylbenzyl chloride and divinylbenzene, and the molar ratio of 4-vinylbenzyl chloride to divinylbenzene is 0.8 to 1.2: 1.
3. The method of claim 1, wherein in step (2), the molar charge of the branched polyethyleneimine is 0.6-0.9 equivalent of benzyl group.
4. The method as claimed in claim 1, wherein in step (2), the molecular weight of the branched polyethyleneimine is 600-2000 daltons, and the branching degree is about 60 ± 5%.
5. The method according to claim 1, wherein 8 to 40 phosphines are added to each branched polyethyleneimine in the step (3).
6. The production method according to claim 1, wherein in the step (4), the amount of Au (I) to be added is (1. + -. 0.5): 1 dose such as plunge; the lower the phosphine content, the closer the ratio of the two is to 1: 1.
7. ultra-small supported gold nanoclusters are prepared from claims 1-6.
8. The gold nanocluster material obtained from claim 7 for use in catalytic reduction of various substrates.
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| CN103002984A (en) * | 2010-03-29 | 2013-03-27 | Sk新技术株式会社 | Catalyst having surface-modified metal nanoparticles immobilized in stationary phase in which a polymer electrolyte membrane is formed, and preparation method thereof |
| CN113070100A (en) * | 2021-03-23 | 2021-07-06 | 同济大学 | Trace thioether-assisted polyamine patch modulated load gold nanocluster and catalytic application thereof |
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| CN103002984A (en) * | 2010-03-29 | 2013-03-27 | Sk新技术株式会社 | Catalyst having surface-modified metal nanoparticles immobilized in stationary phase in which a polymer electrolyte membrane is formed, and preparation method thereof |
| CN113070100A (en) * | 2021-03-23 | 2021-07-06 | 同济大学 | Trace thioether-assisted polyamine patch modulated load gold nanocluster and catalytic application thereof |
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