CN1212262C

CN1212262C - Method for preparing nano line of oxide of transition metals and nano crystals with multi-holes in 3D

Info

Publication number: CN1212262C
Application number: CN 03114802
Authority: CN
Inventors: 岳斌; 贺鹤勇; 朱卡克
Original assignee: Fudan University
Current assignee: Fudan University
Priority date: 2003-01-09
Filing date: 2003-01-09
Publication date: 2005-07-27
Anticipated expiration: 2023-01-09
Also published as: CN1431144A

Abstract

The present invention relates to a method for preparing a nanometer wire and a three-dimensional porous nanometer crystal of transition metal oxide. Nanometer wire products produced by the prior art have the defects of low yield, few varieties, irregular sizes, etc. In the present invention, a SiO<2>-type mesapore solid is used as a template, and the surface of the pore is modified by silicon amination; acid-base neutralization is utilized for controlling the isopoly acid and heteropoly acid of a transition element to orderly flow into a pore canal, and the coordination of amine and transition metal ions can also be utilized for introducing the transition metal ions. Various nanometer wires and three-dimensional porous nanocrystals of transition metal oxide are prepared by controlling the content, the ingredient, the heat decomposition temperature, the heat treating time and the silicon dissolving of an introduced substance. The method which utilizes a chemical control technique has the advantages of simple manufacturing process, high speciality, and strong controllability and is convenient for the preparation of nanometer material with a homogeneous size.

Description

A kind of transition metal oxide nano line or three-dimensional porous nano crystalline preparation method

Technical field

The present invention is a kind of transition metal oxide nano-particles, nano wire or three-dimensional porous nano crystalline preparation method.

Background technology

Nanosecond science and technology develop rapidly since the eighties in 20th century, a kind of new form that the nano material of size between 0.1-100nm exists as material has been subjected to people's common concern, nano material has small size, complex configuration, high integration and characteristics such as strong interaction, high surface area, for crucial effects will being arranged with the ultramicronising of components and parts, the development in Hi-Tech that high-density is integrated into feature, the application of nano material and nanotechnology simultaneously for resources effective develop, the energy make full use of and the removing of environmental pollution also will play a significant role.

The preparation of nano material is the core subdiscipline of the richest originality and vitality in the nanosecond science and technology field, because nano material has at least one dimension to be in the nanoscale scope in three-dimensional space, nano material roughly can be divided into the nanometer powder, unidimensional nanofiber of zero dimension, nanometer film, three-dimensional nano block and the nano composite material etc. of two dimension, the preparation of nanometer powder mainly contains vapor phase process, liquid phase method, solid phase method three classes, each class comprises multiple physics, chemical process again, and the preparation of nanometer powder also is the basis of other nano materials of preparation.

The notion of mesoporous solid is formal the proposition in 1992, and according to the classification of IUPAC, the aperture of mesoporous solid is (K.S.W.Sing etc., PureAppl.Chem.1985,57,603) in the 2-50nm. scope.Mesoporous solid develops over 10 years rapidly, and new mesoporous solid emerges in an endless stream, and according to the difference of building-up process the representational mesoporous solid of four classes is arranged roughly: 1) silicon-dioxide and pure aluminium silicate M41S series, (the C.T.Kresge etc. of research group of 1992 Mobil companies, Nature 1992,359, and 710; J.S.Beck etc., J.Am.Chem.Soc.1992,114,10834; US Patent:5057 296,1991; 5 098 684,1992; 5 108 725,1992; 5 145 816,1992; 5 156 829,1992; 5 183 561,1993; 5 264 203,1993; 5,334 368,1994; 5 370 785,1994) (cetyl trimethylammonium bromide CTAB) as structure directing agent, successfully synthesizes the MCM-41 of six side's phases, the MCM-48 and the lamellated MCM-50 of cube phase in succession with the ionic surfactant; 2) the silicon-dioxide HMS and the MSU of six side's phases, and Pinnavaia research group in 1994 (Nature 1994,368, and 321; Science 1995,167, and 865; Angew.Chem.Int.Ed.1997,36,516) be precursor with oligomeric silicon-dioxide, under the effect of nonionic primary amine (as hexadecylamine) tensio-active agent, rely on hydrogen bond action to carry out self-assembly, synthesized the low six side's aerosil mesoporous solids (HMS and MSU) of the degree of order with honeycomb structure structure; 3) SBA-15 and SBA series, (Science 1998 for G.D.Stucky in 1998 and co-worker thereof, 279,548) with amphiphilic diblock and triblock copolymer as structure directing agent, synthesized six side SBA-15 (P of big (can reach 50nm), wall thicker (typical wall thickness be 3 and 9nm) of long-range order, aperture _6mm), compare SBA-15 with preceding two classes and have higher thermostability and hydrothermal stability.SBA series also comprises SBA-1, SBA-12, the SBA-16 (I of cube phase in addition _M3m), three-dimensional six sides' SBA-2, SBA-3, heteroatomic SBA series mesoporous solids such as zonal SBA-8 etc. and introducing vanadium, aluminium, titanium, zirconium, molybdenum, cobalt; 4) organic-inorganic hybrid mesoporous solid is as the HMM-1 (S.Inagaki etc., J.Am.Chem.Soc.1999,121,9611) etc. of two dimension six side's phases.

Because the aperture of mesoporous solid is in the range scale of nano material, mesoporous solid just might prepare nano material as hard mould agent, and mesoporous solid is similar to the nano level reactor.(Chem.Commun.1996 such as R.Ryoo, 2467), (Chem.Commun.2000 such as P.Yang, 1063) be that template has prepared Pt and Ag nano wire with MCM-41, (Chem.Mater.2000 such as G.DStucky, 12,2068) be that template has prepared Ag and Au nano wire with SBA-15, A.Fukuoka etc. (J.Am.Chem.Soc.2001,123,3373) are that template has prepared Pt-Rh with HMM-1, Pt-Pd, Pt and Rh nano wire are in addition owing to also exist between SBA-15 mesoporous and connect micropore, (Microscopyand Microanalysis 2002 such as O.Terasaki, 8,35) also reported nanometer Pt line with three-dimensional structure.The duct internal surface of silica-type mesoporous solid has slightly acidic silicon hydroxyl, the principle of aforesaid method institute foundation relies on subacidity surface and precursor to interact exactly, thereby effect is more weak, the precursor charge capacity is low, easily by wash-out, handle the back at certain condition and destroy template, preparation-obtained nano wire productive rate is low, yardstick is uneven, kind few (mainly being precious metal up to now).

Summary of the invention

The objective of the invention is to set up that a kind of method is simple, suitability is wide, the precursor charge capacity is big, productive rate is high, the nano wire of yardstick homogeneous or three-dimensional manometer crystalline preparation method.

The present invention is a hard mould agent with the silica-type mesoporous solid, adopt the amino reagent of silicon, as γ-An Bingjisanyiyangjiguiwan (APTS), N-β (aminoethyl)-γ-An Bingjisanjiayangjiguiwan (AEAPTS) mesoporous solid duct internal surface being carried out the silicon amination modifies, make the weakly acidic silicon hydroxyl surface of script become alkaline amido, make polyacid firmly load in the duct thereby can carry out acid-base neutralisation with the polyacid of transition element; In addition because the Lewis alkalescence of amido, thereby can metal-salt firmly be loaded in the duct with multiple transition metal ion coordination.Owing to interact by chemical bond between surface, duct and polyacid species or the transition metal, make precursor be easy to load, stability is strong, avoids.

The present invention places solvent with the silica-type mesoporous material, solvent can be selected as required, as aromatic series kind solvents such as benzene, toluene, or alcoholic solvents such as methyl alcohol, ethanol, add the amino reagent of silicon, generally, obtain the amidized mesoporous material of hole surface silicon in 60-100 ℃ of following stirring and refluxing 4-8 hour after-filtration, washing, oven dry.Then silicon amination mesoporous material is placed and be dissolved with 10 ^-3-10 ^-4The isopoly-acid of mol% transition metal, heteropolyacid, or in the solution of transition metal salt stirring and refluxing 4-8 hour filter, washing, oven dry, handle 3-8 hour under 300-800 ℃ of temperature, make to introduce species and be decomposed into oxide compound.Use the diluted hydrofluoric acid dissolve silica at last, after filtration, after the washing, oven dry, can obtain introducing the transition metal nano wire or the three-dimensional porous nano crystal of species.

Introducing species concentration is higher when it is worthy of note preparation, treatment temp is higher, the treatment time is long partially, and the transition metal oxide nano line enters micropore and is three dimensional growth, and the product that obtain this moment is the three-dimensional porous nano crystal.

In the above-mentioned preparation process, the species of introducing can be isopoly-acid, the heteropolyacid of transition element such as vanadium, tungsten, molybdenum, for example H ₆V ₁₀O ₂₈, H ₃PMo ₁₂O ₄₀, H ₃PW ₁₂O ₄₀, H ₆P ₂W ₁₈O ₆₂Deng, transition metal salt such as manganese acetate, iron nitrate etc.

Mesoporous solid carries out the silicon amination in the solution of siliceous amino reagent, can regulate the silicon amino content on mesoporous solid surface as required by concentration, reflux temperature, the return time of the amino reagent of silicon in the control solution, these those skilled in the art all can be according to existing techniques in realizing.

Analyze and the detection of original position X-ray powder diffraction by differential thermal-weightlessness, the nano effect of a large amount of heat releases and loaded article when load has the silicon amination mesoporous solid of precursor to decompose owing to organism, loaded article can be at a lower temperature, be to take place in the 300-600 ℃ of scope to decompose to generate the crystalline oxide nano wire, be arranged in the duct of mesoporous solid.

If above-mentioned treatment temp in 600-800 ℃ of scope, then generates the three-dimensional porous nano crystal.

Oxide compound generates the back with 10% or the hydrofluoric acid dissolution silicon dioxide hard template of following concentration, removes silicon-dioxide after repeatedly washing and drying fully, obtains pure metal oxide nano-wire or three-dimensional manometer crystal.

The present invention adopts chemical process fully, with the silica-type mesoporous solid is hard template, the duct internal surface is carried out the silicon amination to be modified, utilizing acid-base neutralisation to make the isopoly-acid of transition element and heteropolyacid enter the duct in order combines with amido, also can utilize amido and transition metal ion coordination to introduce transition metal ion, content, composition, heat decomposition temperature, heat treatment time and the silicon of introducing species by control dissolve, and prepare multiple transition metal oxide nano line or its three-dimensional porous nano crystal.This method adopts chemical control technology, and technology is simple, the specificity height, and controllability is strong, and is applied widely, is convenient to multiple transition metal oxide nano line or its three-dimensional manometer crystal of preparation scale homogeneous.

Description of drawings

Fig. 1 is WO ₃The TEM figure of nano wire.

Fig. 2 is WO ₃Three-dimensional manometer crystalline TEM figure.

Fig. 3 is MnO ₂The TEM figure of nano wire.

Fig. 4 is Cr ₂O ₃Three-dimensional manometer crystalline HRTEM schemes (a) and electron-diffraction diagram (b).

Embodiment

Embodiment 1:

WO ₃Nano wire or the preparation of three-dimensional manometer crystalline: 1g SBA-15 is added 30ml contain in the toluene solution of 1%APTS, stirring and refluxing 5h filters, and uses toluene wash, and 95 ℃ of oven dry were handled 3 hours, obtained the amidized SBA-15 of silicon (APTS/SBA-15).1g APTS/SBA-15 adds 30ml tungstenic phosphatase 11 .0 * 10 ^-3In the methanol solution of mol, stirring and refluxing 8h, filtration washing is dried for 95 ℃ and is handled 3 hours (H then ₃PW ₁₂O ₄₀/ APTS/SBA-15), then with 2 ℃ of min ^-1Speed be warming up to 400 ℃, the insulation 7h, the gained solid is removed silicon-dioxide with 10% hydrofluoric acid dissolution, obtains WO after washing and drying ₃Crystalline state nano wire (see figure 1).If with H ₃PW ₁₂O ₄₀/ APTS/SBA-15 gets treatment temp and rises to 650 ℃, treatment time 8h, then can obtain WO ₃Three-dimensional manometer crystal (see figure 2).

Embodiment 2:

MnO ₂The preparation of nano wire: the amidized MCM-41 of AEAPTS silicon is at Mn ²⁺Heated in water solution stirring and refluxing 5h after-filtration, washing, oven dry slowly are warming up to 600 ℃ then, and thermal treatment 5h, gained sample obtain MnO after removing silicon-dioxide with hydrofluoric acid ₂The nano wire (see figure 3).

Embodiment 3:

Cr ₂O ₃The preparation of three-dimensional manometer crystalline: the amidized SBA-15 of APTS silicon is at the 10%K of pH=1.5 ₂Cr ₂O ₇Stirring and refluxing is about 8 hours in the aqueous solution, after filtering, wash, drying, handles about 3 hours at 700 ℃, and the gained sample obtains Cr after removing silicon-dioxide with hydrofluoric acid ₂O ₃Three-dimensional manometer crystal (see figure 4).

The present invention is not limited to the foregoing description, and the isopoly-acid of transition element, heteropolyacid, transition metal salt such as those skilled in the art such as manganese acetate, iron nitrate all can implement according to by way of example.

Claims

1, a kind of transition metal oxide nano line or three-dimensional porous nano crystalline preparation method is characterized in that:

(1) use the silica-type mesoporous material as template;

(2) the silicon amination step of mesoporous material is about to a certain amount of silica-type mesoporous material and places aromatic series kind solvent or alcoholic solvent, adds the amino reagent of silicon, and stirring and refluxing after-filtration, washing, oven dry obtain the amidized mesoporous material of hole surface silicon;

(3) above-mentioned silicon amination mesoporous material places and is dissolved with 10 ^-3-10 ^-4The isopoly-acid of mol% transition metal, heteropolyacid, or in the transition metal salt solution stirring and refluxing 4-8 hour filter, washing, oven dry, handle 3-8 hour at 300-800 ℃, make to introduce species and be decomposed into oxide compound;

(4) be 10% or following hydrofluoric acid dissolution silicon-dioxide with concentration, filter, after the washing, oven dry, obtain nano wire or three-dimensional porous nano crystal.

2, transition metal oxide nano line according to claim 1 or three-dimensional porous nano crystalline preparation method, it is characterized in that introducing the species treatment temp is 300-600 ℃, obtains the transition metal oxide nano line.

3, transition metal oxide nano line according to claim 1 or three-dimensional porous nano crystalline preparation method, it is characterized in that introducing the species treatment temp is 600-800 ℃, obtains transition metal oxide three-dimensional porous nano crystal.