CN104815685A - Magnetic multistage nuclear @ shell structure nano-palladium catalyst and preparation method thereof - Google Patents
Magnetic multistage nuclear @ shell structure nano-palladium catalyst and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a magnetic multistage nuclear @ shell structure nano-palladium catalyst and a preparation method thereof, and belongs to the field of magnetic nano-catalysis materials. The general form of the materials is Fe3O4@MAl-LDH@xPd0, wherein the MAl-LDH refers to shell hydrotalcite, the M refers to one or two divalent metal elements, and the x refers to the weight percent load of palladium. By a low-temperature double-dipping co-precipitation method, LDH nano-crystals are assembled on the surface of a Fe3O4 magnetic nuclear surface, shell LDH hexagonal nano-crystals grow in a mutually staggered mode in such a manner that ab surfaces are perpendicular to the magnetic nuclear surface, and the shell LDH hexagonal nano-crystals are honeycomb. By an impregnation reduction method, palladium nano-particles are loaded on a magnetic multistage nuclear @ shell structure carrier to obtain a primary magnetic multistage nuclear @ shell structure nano-palladium catalyst, and the palladium nano-particles are uniformly distributed at edges and staggered positions of the LDH nano-crystals. The obtained catalyst is used for iodobenzene and styrene Heck coupling reaction and has fine catalytic activity, the highest TOF value is 160.5h-1, the catalyst is recycled by an external magnetic field, and the catalytic activity is not obviously reduced after used for ten times.
Description
Technical field
The invention belongs to magnetic Nano catalysis material technical field, particularly relate to a kind of magnetic multistage core@shell structural nano palladium catalyst and preparation method thereof, this magnetic Nano palladium catalyst can be applicable to the fields such as the coupling of carbon carbon, hydrogenation of olefins and alcohol oxidation.
Background technology
In organic synthesis field, carbon carbon coupling reaction is the chemical reaction that a class substrate applicability is good, is widely used in the synthesis of organic intermediate.Common carbon carbon coupling reaction catalyst mainly with transition metal such as copper, nickel, palladiums for active specy.Wherein, homogeneous palladium catalysts especially receives much concern because catalytic activity is excellent containing the palladium catalyst of organophosphorus ligand, but also also exists air, moisture-sensitive simultaneously and reclaim the problems such as difficulty.Therefore, select that the preparation of suitable carrier material is green, efficient heterogeneous palladium catalyst has important practical significance.
Anionic clay hydrotalcite (Layered double hydroxides) is a kind of typical two-dimensional layer material.Hydrotalcite material can be grabbed hydrogen bond by the class acting on surface and be formed load type palladium catalyst as the Pd-HO key between metallic bond and covalent bond and Metal Palladium nano particle Direct Bonding, can be applicable to the fields such as the coupling of carbon carbon, hydrogenation of olefins and alcohol oxidation.Choudary etc. (B.M.Choudary, Sattesh Madhi, N.S.Chowdari, et al., J.Am.Chem.Soc., 2002,124,14127-14136) for precursor, adopt ion-exchange by PdCl with the magnalium hydrotalcite of chlorion intercalation
4 2-introduce interlayer, then use hydrazine hydrate reduction PdCl in ethanol
4 2-obtain the zero valent palladium catalyst of magnalium hydrotalcite load, its Pd nano particle is of a size of 4 ~ 6nm, and the catalytic activity of this catalyst to 4-chloroanisole and styrene Heck coupling reaction is obviously better than Pd/C and Pd/Al
2o
3.Li etc. (P.Li, P.P.Huang, F.F.Wei, et al., J.Mater.Chem.A, 2014,2,12739-12745) adopt hydro-thermal method to synthesize flower-shaped cobalt aluminum hydrotalcite using urea as alkali, then by laminate Co
2+with PdCl
4 2-in-situ oxidation reduction process at carrier surface supported palladium nano-cluster, obtain a kind of multi-level flower-like structure palladium catalyst, its Pd nano particle size is about 2nm, and this catalyst application is in the Suzuki coupling reaction of catalysis iodobenzene, and reaction 5min product yield reaches 98%.Although independent hydrotalcite load type palladium catalyst is recycled by conventional solid-liquid separation means such as centrifugal, filtration etc., still can at substantial time and manpower.And magnetic/functionalized heterogeneous nanocatalyst can be able to quick separating by externally-applied magnetic field, thus effectively solve the problems such as conventional palladium catalyst separative efficiency is low, consuming time.Ay etc. (A.N.Ay, N.V.Abramova, Deniz Konuk, et al., Inorg.Chem.Commun., 2013,27,64-68) are by NO
3 -ion insertion magnalium hydrotalcite and ferroferric oxide magnetic nano grain (15 ~ 25nm) more than mechanical mixture 48h obtained magnetic mg_al hydrotalcite carrier, then direct load P d in toluene
2(dba)
3species, gained catalyst subglobular, but most of hydrotalcite nano piece is separated in free state with ferroferric oxide magnetic nano grain, its specific saturation magnetization is only 2.53emu/g, be applied to the Heck coupling reaction of catalysis iodobenzene and ethyl acrylate, reaction 10min iodobenzene conversion ratio reaches 100%, but it recycles performance and has no report.Zhang etc. (Chinese invention patent: ZL 201010224523.6) report " honeycomb " shape magnetic multistage core@shell structure magnalium hydrotalcite based nano catalyst of a class novelty, its shell hydrotalcite nano piece vertical interlaced oriented growth, Jenner's grain of rice is supported on hydrotalcite nano piece surface, this catalyst application is in catalysis 1-benzyl carbinol oxidation reaction, reaction 3h conversion ratio can reach 100%, and this catalyst has good superparamagnetism, after recycling 5 times, non-activity reduces.But, up to now, there is no the report of the magnetic multistage core@shell structure hydrotalcite nano Pd catalyst about clear in structure, morphology controllable.
Thus, this patent is intended adopting the two coprecipitations of dripping improved at Fe
3o
4the hydrotalcite nano of magnetic nano particle surface ordered fabrication difference composition is brilliant, obtain a series of magnetic multistage core@shell structure hydrotalcite complex carrier, subsequently, adopt easy immersion reduction method supported palladium nano particle on above-mentioned complex carrier, prepare a class magnetic multistage core@shell structure without part Technique of Nano Pd heterogeneous catalyst.The basic character of this collection of material hydrotalcite material itself and laminate to palladium complex anion (as PdCl
4 2-ion) peptizaiton and Fe
3o
4the superparamagnetism that magnetic nano particle is excellent, realizes the effective utilization to precious metal palladium.Such catalyst is expected to be applied to that carbon carbon is coupling catalysed, the organic synthesis field such as hydrogenation of olefins and alcohol oxidation.
Summary of the invention
The object of the present invention is to provide a kind of magnetic multistage core@shell structural nano palladium catalyst and preparation method thereof, magnetic multistage core@shell structure hydrotalcite nano Pd catalyst of " honeycomb " shape and preparation method thereof.
Such catalyst is with Fe
3o
4magnetic nano particle is core, with CO
3 2-mgAl, CoAl, NiAl, NiMgAl, CoMgAl and NO of intercalation
3 -the CaMgAl-LDH of intercalation is shell structurre, without part zeroth order Pd nano particle uniform load in the edge of shell hydrotalcite six square piece and staggered position; The chemical general formula of such catalyst is Fe
3o
4@MAl-LDH@xPd
0, wherein, MAl-LDH is that ab-face is perpendicular to Fe
3o
4surface and the shell hydrotalcite hexagonal nano of interlaced growth is brilliant, Pd
0for be uniformly distributed in MAl-LDH hexagonal nano crystal edge edge and staggered position without part zeroth order Pd nano particle, x is the mass percent load capacity of palladium, and unit is wt%; Wherein, the mass percentage of each component is respectively:
Fe
3O
4：35.3～49.8％；
MAl-LDH：47.7～61.5％；
Pd
0：0.18～3.43％。
Wherein M is one or both divalent metals, can be Mg, Ni, Co, NiMg, CoMg and CaMg; The interlayer anion of shell MAl-LDH can be CO
3 2-or NO
3 -anion.
This magnetic palladium catalyst integral particles is of a size of 400 ~ 600nm, and specific saturation magnetization is 38.6 ~ 54.9emu/g, and specific area is 63 ~ 74m
2/ g; Hydrotalcite shell thickness is 80 ~ 120nm, and single hydrotalcite nano crystalline substance is of a size of 65 ~ 100nm, and thickness is 8 ~ 10nm, and the pore-size between hydrotalcite nano crystalline substance is 55 ~ 110nm; Pd nano particle is of a size of 3.9 ~ 12.1nm.
Such catalyst has good catalytic activity, especially Fe to iodobenzene and cinnamic Heck coupling reaction
3o
4@[email protected]
0catalyst use amount be 0.601mol%, under reaction temperature is 120 DEG C, reaction medium is the reaction condition of DMF, TOF value is up to 160.5h
-1, active in obviously reducing after recycling 10 times.
The present invention makes Fe by oneself with laboratory
3o
4magnetic nano particle is core, coprecipitation is dripped in its surface-assembled MAl-LDH shell structurre (wherein by two under ice-water bath or room temperature condition, M is one or both divalent metals, can be Mg, Ni, Co, CaMg, NiMg and CoMg), without the need to the crystallization process that additionally heats up, again with immersion reduction method load zeroth order Pd nano particle in above-mentioned magnetic hydrotalcite, obtain a class and there is the hydrotalcite of multistage core@shell structure and " honeycomb " shape pattern without part Technique of Nano Pd magnetic catalyst.Concrete technology step is as follows:
(1) preparation of magnetic nano particle
Surfactant-free solvent-thermal method is adopted to prepare ferroferric oxide magnetic nano grain, same to Chinese invention patent: ZL201110344754.5.
Take 2.16g FeCl
36H
2o is dissolved in 80mL ethylene glycol in 30 ~ 50 DEG C of water-baths, obtained stable homogeneous orange solution, and concentration is 0.1mol/L; Add 5.76g NaAc3H
2o, is slowly stirred to and dissolves completely, avoids producing bubble, NaAc3H
2o and FeCl
36H
2the mol ratio of O is 5.29; Being transferred to 100mL liner is in the self-generated pressure bullet appearance of polytetrafluoroethylene (PTFE), in 200 DEG C of reaction 8h.Naturally cool to room temperature, adopt Nd-Fe-B permanent magnet magnetic to be separated, wash 5 times respectively by ethanol and deionized water, in 60 DEG C of drying 24 ~ 48h, obtain black powder magnetic nano particle, be designated as Fe
3o
4.
(2) preparation of magnetic multistage core@shell structure hydrotalcite supports
The two coprecipitations of dripping improved are adopted to prepare magnetic multistage core@shell structure hydrotalcite supports.
The first step: M pressed by divalent metal salt and aluminium salt
2+/ Al
3+the molar concentration rate of=3, is made into mixing salt solution with water, and concentration is 0.03 ~ 0.09mol/L; Another preparation contains NaOH and Na
2cO
3mixed ammonium/alkali solutions, the concentration of NaOH is 0.2mol/L, Na
2cO
3concentration be 0.06mol/L (in magnetic CaMgAl-LDH system, the solute of aqueous slkali only has NaOH); Take 1.042g Fe
3o
4magnetic nano particle (surfactant-free solvent-thermal method prepare, about 400nm) ultrasonic disperse 20min in 100mL water forms black suspension, and wherein in hydrotalcite laminate diad M and magnetic core, the molal quantity ratio of Fe element is 0.25 ~ 0.75;
Wherein M is one or more divalent metals, can be Mg, Ni, Co, CaMg, NiMg or CoMg, and the anion of soluble M salt and Al salt is NO
3 -or Cl
-.
Second step: by Fe
3o
4suspension is placed in 500mL four-hole boiling flask, and Quick mechanical stirs (magnetic CaMgAl-LDH system need be protected with nitrogen atmosphere).In ice-water bath (magnetic CoAl and CoMgAl-LDH system) or room temperature (magnetic MgAl, NiAl, NiMgAl and CoMgAl-LDH system), with mixed ammonium/alkali solutions by Fe
3o
4the pH value of suspension is slowly adjusted to required numerical value and (for magnetic MgAl, NiAl, CoAl, NiMgAl and CoMgAl-LDH system, precipitates pH and be adjusted to 10; For magnetic CaMgAl-LDH system, precipitation pH is adjusted to 11.5), stablize 5 ~ 10min, subsequently mixing salt solution and mixed ammonium/alkali solutions are slowly added drop-wise in above-mentioned suspension simultaneously, drop rate is 1 ~ 1.5mL/min, keeps slurries pH constant, after mixing salt solution dropwises in dropping process, stop dripping mixed alkali liquor, continue to keep rapid stirring slurries 5min.
3rd step: adopt Nd-Fe-B permanent magnet magnetic to be separated black solid product, spend the above-mentioned solid of deionized water repeatedly to supernatant pH in neutral, in 60 DEG C of dry 24-48h (magnetic CaMgAl-LDH system needs vacuum drying), grinding obtains black powder magnetic multistage core@shell structure hydrotalcite supports, is designated as Fe
3o
4@MAl-LDH.
(3) preparation of magnetic multistage core@shell structural nano palladium catalyst
Adopt immersion reduction method load zeroth order palladium nanoparticle in above-mentioned magnetic multistage core@shell structure hydrotalcite supports.
Take the above-mentioned magnetic of 1g multistage core@shell structure hydrotalcite supports Fe
3o
4@MAl-LDH is scattered in 100mL ethanol, and Quick mechanical stirs.0.17 ~ 8.33mL tetrachloro-palladium acid aqueous solutions of potassium (0.56mol/L) is joined in above-mentioned suspension.Subsequently, add 1mL hydrazine hydrate, under 25 DEG C of conditions, reduce 3h.Adopt Nd-Fe-B permanent magnet magnetic to be separated black solid, wash repeatedly to neutral by ethanol and deionized water, in 60 DEG C of vacuum drying 24 ~ 48h, grinding obtains black powder magnetic multistage core@shell structural nano palladium catalyst, is designated as Fe
3o
4@MAl-LDH@xPd
0(x=0.18 ~ 3.43).
Wherein, at Fe
3o
4@CaMgAl-LDH@xPd
0synthesis step in, all experimental waters are the deionized water of boiling carbon dioxide removal.
Advantage of the present invention is:
[1] first at ambient temperature, the two coprecipitations of dripping without extra intensification crystallization process are adopted to obtain magnalium, nickel aluminium, nickel magnalium and the calcium magnalium hydrotalcite carrier material with magnetic multistage core@shell structure and " honeycomb " shape pattern; Wherein, magnetic CaMgAl-LDH carrier material needs to adopt nitrogen atmosphere to protect in building-up process, and required aqueous slkali is only using NaOH as solute.
[2] first under ice-water bath condition, adopt and drip obtained cobalt aluminium and the cobalt magnalium hydrotalcite carrier material with magnetic multistage core@shell structure and " honeycomb " shape pattern of coprecipitation without the two of extra intensification crystallization process.
[3] with tetrachloro-palladium potassium chlorate be palladium source first, the load on above-mentioned 6 kinds of magnetic hydrotalcite carrier materials of easy immersion reduction method is adopted without part zeroth order palladium nanoparticle, to obtain the magnetic Nano palladium catalyst that 6 kinds have magnetic multistage core@shell structure and " honeycomb " shape pattern respectively.
[4] with green solvent---water is co-precipitation medium, by the condition of adjustment hydrotalcite in the vertical orientated growth in surface of magnetic core, as metal nitrate/villaumite kind and concentration, nucleation temperature and precipitation pH etc., realize the chemical composition to such magnetic Nano palladium catalyst, appearance structure feature and the isoparametric regulation and control of magnetic property.
[5] be carrier loaded without part zeroth order palladium nanoparticle to have the magnetic cobalt aluminum hydrotalcite of magnetic multistage core@shell structure and " honeycomb " shape pattern, gained catalyst palladium load capacity be 0.80%, use amount is 0.601mol%, reaction temperature be 120 DEG C and reaction medium is N, under the reaction condition of dinethylformamide, the transformation frequency TOF value in catalysis iodobenzene and styrene heck coupling process is up to 160.5h
-1.
Accompanying drawing explanation
Fig. 1 is Fe in embodiment 1-7
3o
4the TEM spectrogram of magnetic nano particle sample.
Fig. 2 is magnetic Multilevel-structure hydrotalcite carrier Fe in embodiment 1 and embodiment 7
3o
4the SEM spectrogram of@MgAl-LDH.
Fig. 3 is magnetic multilevel hierarchy nano Pd catalyst Fe in embodiment 1
3o
4@[email protected]
0sEM spectrogram.
Fig. 4 is magnetic Multilevel-structure hydrotalcite carrier Fe in embodiment 3 and embodiment 6
3o
4the SEM spectrogram of@NiAl-LDH.
Fig. 5 is magnetic multilevel hierarchy nano Pd catalyst Fe in embodiment 3
3o
4@[email protected]
0sEM spectrogram.
Detailed description of the invention
Embodiment 1
(1) preparation of magnetic nano particle
Get 2.16g FeCl
36H
2o is dissolved in 80mL ethylene glycol in 40 DEG C of water-baths, obtained stable homogeneous solution; Add 5.76g NaAc3H
2o, is slowly stirred to and dissolves completely, avoids producing bubble; Being transferred to 100mL liner is during polytetrafluoroethylene (PTFE) self-generated pressure bullet holds, 200 DEG C of reaction 8h.Naturally cool to room temperature, be separated with Nd-Fe-B permanent magnet magnetic, ethanol washs 5 times, then with deionized water washing to neutral, 60 DEG C of dry 24h, obtain black powder magnetic nano particle, be designated as Fe
3o
4.Transmission electron microscope results (accompanying drawing 1) shows gained Fe
3o
4magnetic nano particle is the spheroidal particle that particle diameter is about 400nm; Vibrating example magnetic strength test result shows that it has typical superparamagnetism, and specific saturation magnetization is 76.5emu/g.
(2) preparation of magnetic multistage core@shell structure hydrotalcite supports
Take 1.042g Fe
3o
4nanoparticle is placed in 100mL water ultrasonic disperse 20min.By 2.310gMg (NO
3)
26H
2o and 1.125g Al (NO
3)
39H
2o is dissolved in 100mL water, obtains mixing salt solution.By 0.640gNa
2cO
3be dissolved in 100mL water, as aqueous slkali with 0.800g NaOH.In 25 DEG C of water-baths, slowly drip a small amount of aqueous slkali to Fe
3o
4in suspension, be 10 to pH, stablize 5min.Drip alkali lye subsequently simultaneously and mix saline solution, vigorous stirring, maintenance pH is 10 until salt-mixture liquid dropwises.Be separated this product with Nd-Fe-B permanent magnet magnetic, wash 5 times with deionized water, in 60 DEG C of vacuum drying 24h, obtain magnetic multistage core@shell structure hydrotalcite supports, be designated as Fe
3o
4@MgAl-LDH.ESEM (accompanying drawing 2) and transmission electron microscope results show the interlaced growth of its shell hydrotalcite nano piece and ab-face is surperficial perpendicular to magnetic core, the surface topography of entirety presents " honeycomb " shape, hydrotalcite shell thickness is about 120nm, single hydrotalcite nano piece size is about 100nm, and thickness is about 10nm; Vibrating example magnetic strength test result shows that its specific saturation magnetization is 36.1emu/g.
(3) preparation of magnetic multistage core@shell structural nano palladium catalyst
Take the above-mentioned Fe of 1g
3o
4@MgAl-LDH is scattered in 100mL ethanol.8.33mL tetrachloro-palladium acid aqueous solutions of potassium (0.56mol/L) is joined in above-mentioned suspension.Subsequently, add 1mL hydrazine hydrate, after 25 DEG C of reaction 3h, with Nd-Fe-B permanent magnet magnetic separated product, with ethanol and water washing repeatedly to neutral, in 60 DEG C of vacuum drying 24h, obtain black powder magnetic multistage core@shell structural nano palladium catalyst, be designated as Fe
3o
4@[email protected]
0.Through characterizing the composition mass percent of this magnetic Nano palladium catalyst be: Fe
3o
4nanoparticle is 37.1%, and hydrotalcite is 59.6%, and palladium is 3.32%; ESEM (accompanying drawing 3) show the interlaced growth of its shell hydrotalcite nano piece and ab-face perpendicular to magnetic core surface, the surface topography of entirety presents " honeycomb " shape and favorable dispersibility; High-resolution-ration transmission electric-lens display Pd nano particle average-size is 12.1nm; The specific saturation magnetization of vibrating example magnetic strength test result display catalyst is 38.6emu/g; The specific area of specific area-pore analysis display catalyst is 63.5m
2/ g.
Embodiment 2
(1) preparation of magnetic nano particle
Get 2.16g FeCl
36H
2o is dissolved in 80mL ethylene glycol in 40 DEG C of water-baths, obtained stable homogeneous solution; Add 5.76g NaAc3H
2o, is slowly stirred to and dissolves completely, avoids producing bubble; Being transferred to 100mL liner is during polytetrafluoroethylene (PTFE) self-generated pressure bullet holds, 200 DEG C of reaction 8h.Naturally cool to room temperature, be separated with Nd-Fe-B permanent magnet magnetic, ethanol washs 5 times, then with deionized water washing to neutral, 60 DEG C of dry 24h, obtain black powder magnetic nano particle, be designated as Fe
3o
4, its size and magnetic property are with embodiment 1.
(2) preparation of magnetic multistage core@shell structure hydrotalcite supports
Take 1.042g Fe
3o
4nanoparticle is placed in 100mL water ultrasonic disperse 20min.By 2.622gCo (NO
3)
26H
2o and 1.125g Al (NO
3)
39H
2o is dissolved in 100mL water, obtains mixing salt solution.By 0.640gNa
2cO
3be dissolved in 100mL water, as aqueous slkali with 0.800g NaOH.In 0 DEG C of ice-water bath, slowly drip a small amount of aqueous slkali to Fe
3o
4in suspension, be 10 to pH, stablize 5min.Drip alkali lye subsequently simultaneously and mix saline solution, vigorous stirring, maintenance pH is 10 until salt-mixture liquid dropwises.Be separated this product with Nd-Fe-B permanent magnet magnetic, wash 5 times with deionized water, in 60 DEG C of vacuum drying 24h, obtain magnetic multistage core@shell structure hydrotalcite supports, be designated as Fe
3o
4@CoAl-LDH.It is 43.3emu/g that vibrating example magnetic strength test result shows its specific saturation magnetization; Scanner uni transmission electron microscope results shows the interlaced growth of its shell hydrotalcite nano piece and ab-face is surperficial perpendicular to magnetic core, the surface topography of entirety presents " honeycomb " shape and favorable dispersibility, hydrotalcite shell thickness is about 100nm, and single hydrotalcite nano piece size is about 76nm, and thickness is about 10nm.
(3) preparation of magnetic multistage core@shell structural nano palladium catalyst
Take the above-mentioned Fe of 1g
3o
4@CoAl-LDH is scattered in 100mL ethanol.8.33mL tetrachloro-palladium acid aqueous solutions of potassium (0.56mol/L) is joined in above-mentioned suspension.Subsequently, add 1mL hydrazine hydrate, after 25 DEG C of reaction 3h, with Nd-Fe-B permanent magnet magnetic separated product, with ethanol and water washing repeatedly to neutral, in 60 DEG C of vacuum drying 24h, obtain black powder magnetic multistage core@shell structural nano palladium catalyst, be designated as Fe
3o
4@[email protected]
0.Through characterizing the composition mass percent of this magnetic Nano palladium catalyst be: Fe
3o
4nanoparticle is 48.9%, and hydrotalcite is 47.7%, and palladium is 3.43%; Scanner uni transmission electron microscope results show the interlaced growth of its shell hydrotalcite nano piece and ab-face perpendicular to magnetic core surface, the surface topography of entirety presents " honeycomb " shape and favorable dispersibility; High-resolution-ration transmission electric-lens result display Pd nano particle average-size is 7.5nm; The specific saturation magnetization of vibrating example magnetic strength test result display catalyst is 54.9emu/g; The specific area of specific area-pore analysis display catalyst is 64.1m
2/ g.
Embodiment 3
(1) preparation of magnetic nano particle
Get 2.16g FeCl
36H
2o is dissolved in 80mL ethylene glycol in 40 DEG C of water-baths, obtained stable homogeneous solution; Add 5.76g NaAc3H
2o, is slowly stirred to and dissolves completely, avoids producing bubble; Being transferred to 100mL liner is during polytetrafluoroethylene (PTFE) self-generated pressure bullet holds, 200 DEG C of reaction 8h.Naturally cool to room temperature, be separated with Nd-Fe-B permanent magnet magnetic, ethanol washs 5 times, then with deionized water washing to neutral, 60 DEG C of dry 24h, obtain black powder magnetic nano particle, be designated as Fe
3o
4, its size and magnetic property are with embodiment 1.
(2) preparation of magnetic multistage core@shell structure hydrotalcite supports
Take 1.042g Fe
3o
4nanoparticle is placed in 100mL water ultrasonic disperse 20min.By 2.620gNi (NO
3)
26H
2o and 1.125g Al (NO
3)
39H
2o is dissolved in 100mL water, obtains mixing salt solution.By 0.640g Na
2cO
3be dissolved in 100mL water, as aqueous slkali with 0.800g NaOH.In 25 DEG C of water-baths, slowly drip a small amount of aqueous slkali to Fe
3o
4in suspension, be 10 to pH, stablize 5min.Drip alkali lye subsequently simultaneously and mix saline solution, vigorous stirring, maintenance pH is 10 until salt-mixture liquid dropwises.Be separated this product with Nd-Fe-B permanent magnet magnetic, wash 5 times with deionized water, in 60 DEG C of vacuum drying 24h, obtain magnetic multistage core@shell structure hydrotalcite supports, be designated as Fe
3o
4@NiAl-LDH.It is 43.4emu/g that vibrating example magnetic strength test result shows its specific saturation magnetization; ESEM (accompanying drawing 4) and transmission electron microscope results show the interlaced growth of its shell hydrotalcite nano piece and ab-face is surperficial perpendicular to magnetic core, the surface topography of entirety presents " honeycomb " shape, hydrotalcite shell thickness is about 80nm, single hydrotalcite nano piece size is about 65nm, and thickness is about 8nm.
(3) preparation of magnetic multistage core@shell structural nano palladium catalyst
Take the above-mentioned Fe of 1g
3o
4@NiAl-LDH is scattered in 100mL ethanol.8.33mL tetrachloro-palladium acid aqueous solutions of potassium (0.56mol/L) is joined in above-mentioned suspension.Subsequently, add 1mL hydrazine hydrate, after 25 DEG C of reaction 3h, with Nd-Fe-B permanent magnet magnetic separated product, with ethanol and water washing repeatedly to neutral, in 60 DEG C of vacuum drying 24h, obtain black powder magnetic multistage core@shell structural nano palladium catalyst, be designated as Fe
3o
4@[email protected]
0.Through characterizing the composition mass percent of this magnetic Nano palladium catalyst be: Fe
3o
4nanoparticle is 35.3%, and hydrotalcite is 61.5%, and palladium is 3.17%; ESEM (accompanying drawing 5) and transmission electron microscope results show the interlaced growth of its shell hydrotalcite nano piece and ab-face perpendicular to magnetic core surface, the surface topography of entirety presents " honeycomb " shape and favorable dispersibility; High-resolution-ration transmission electric-lens result display Pd nano particle average-size is 6.7nm; The specific saturation magnetization of vibrating example magnetic strength test result display catalyst is 44.3emu/g; The specific area of specific area-pore analysis display catalyst is 74.1m
2/ g.
Embodiment 4
(1) preparation of magnetic nano particle
Get 2.16g FeCl
36H
2o is dissolved in 80mL ethylene glycol in 40 DEG C of water-baths, obtained stable homogeneous solution; Add 5.76g NaAc3H
2o, is slowly stirred to and dissolves completely, avoids producing bubble; Being transferred to 100mL liner is during polytetrafluoroethylene (PTFE) self-generated pressure bullet holds, 200 DEG C of reaction 8h.Naturally cool to room temperature, be separated with Nd-Fe-B permanent magnet magnetic, ethanol washs 5 times, then with deionized water washing to neutral, 60 DEG C of dry 24h, obtain black powder magnetic nano particle, be designated as Fe
3o
4, its size and magnetic property are with embodiment 1.
(2) preparation of magnetic multistage core@shell structure hydrotalcite supports
Take 1.042g Fe
3o
4nanoparticle is placed in 100mL water ultrasonic disperse 20min.By 2.622gCo (NO
3)
26H
2o and 1.125g Al (NO
3)
39H
2o is dissolved in 100mL water, obtains mixing salt solution.By 0.640gNa
2cO
3be dissolved in 100mL water, as aqueous slkali with 0.800g NaOH.In 0 DEG C of ice-water bath, slowly drip a small amount of aqueous slkali to Fe
3o
4in suspension, be 10 to pH, stablize 5min.Drip alkali lye subsequently simultaneously and mix saline solution, vigorous stirring, maintenance pH is 10 until salt-mixture liquid dropwises.Be separated this product with Nd-Fe-B permanent magnet magnetic, wash 5 times with deionized water, in 60 DEG C of vacuum drying 24h, obtain magnetic multistage core@shell structure hydrotalcite supports, be designated as Fe
3o
4@CoAl-LDH, its structure and morphology feature and magnetic property are with embodiment 2.
(3) preparation of magnetic multistage core@shell structural nano palladium catalyst
Take the above-mentioned Fe of 1g
3o
4@CoAl-LDH is scattered in 100mL ethanol.1.67mL tetrachloro-palladium acid aqueous solutions of potassium (0.56mol/L) is joined in above-mentioned suspension.Subsequently, add 1mL hydrazine hydrate, after 25 DEG C of reaction 3h, with Nd-Fe-B permanent magnet magnetic separated product, with ethanol and water washing repeatedly to neutral, in 60 DEG C of vacuum drying 24h, obtain black powder magnetic multistage core@shell structural nano palladium catalyst, be designated as Fe
3o
4@[email protected]
0.Be 0.80% through characterizing the palladium content of this magnetic Nano palladium catalyst, palladium particle size is 3.9nm.
Embodiment 5
(1) preparation of magnetic nano particle
Get 2.16g FeCl
36H
2o is dissolved in 80mL ethylene glycol in 40 DEG C of water-baths, obtained stable homogeneous solution; Add 5.76g NaAc3H
2o, is slowly stirred to and dissolves completely, avoids producing bubble; Being transferred to 100mL liner is during polytetrafluoroethylene (PTFE) self-generated pressure bullet holds, 200 DEG C of reaction 8h.Naturally cool to room temperature, be separated with Nd-Fe-B permanent magnet magnetic, ethanol washs 5 times, then with deionized water washing to neutral, 60 DEG C of dry 24h, obtain black powder magnetic nano particle, be designated as Fe
3o
4, its size and magnetic property are with embodiment 1.
(2) preparation of magnetic multistage core@shell structure hydrotalcite supports
Take 1.042g Fe
3o
4nanoparticle is placed in 100mL water ultrasonic disperse 20min.By 2.622gCo (NO
3)
26H
2o and 1.125g Al (NO
3)
39H
2o is dissolved in 100mL water, obtains mixing salt solution.By 0.640gNa
2cO
3be dissolved in 100mL water, as aqueous slkali with 0.800g NaOH.In 0 DEG C of ice-water bath, slowly drip a small amount of aqueous slkali to Fe
3o
4in suspension, be 10 to pH, stablize 5min.Drip alkali lye subsequently simultaneously and mix saline solution, vigorous stirring, maintenance pH is 10 until salt-mixture liquid dropwises.Be separated this product with Nd-Fe-B permanent magnet magnetic, wash 5 times with deionized water, in 60 DEG C of vacuum drying 24h, obtain magnetic multistage core@shell structure hydrotalcite supports, be designated as Fe
3o
4@CoAl-LDH, its structure and morphology feature and magnetic property are with embodiment 2.
(3) preparation of magnetic multistage core@shell structural nano palladium catalyst
Take the above-mentioned Fe of 1g
3o
4@CoAl-LDH is scattered in 100mL ethanol.5.00mL tetrachloro-palladium acid aqueous solutions of potassium (0.56mol/L) is joined in above-mentioned suspension.Subsequently, add 1mL hydrazine hydrate, after 25 DEG C of reaction 3h, with Nd-Fe-B permanent magnet magnetic separated product, with ethanol and water washing repeatedly to neutral, in 60 DEG C of vacuum drying 24h, obtain black powder magnetic multistage core@shell structural nano palladium catalyst, be designated as Fe
3o
4@[email protected]
0.Be 2.51% through characterizing the palladium content of this magnetic Nano palladium catalyst, palladium particle size is 5.8nm.
Embodiment 6
(1) preparation of magnetic nano particle
Get 2.16g FeCl
36H
2o is dissolved in 80mL ethylene glycol in 40 DEG C of water-baths, obtained stable homogeneous solution; Add 5.76g NaAc3H
2o, is slowly stirred to and dissolves completely, avoids producing bubble; Being transferred to 100mL liner is during polytetrafluoroethylene (PTFE) self-generated pressure bullet holds, 200 DEG C of reaction 8h.Naturally cool to room temperature, be separated with Nd-Fe-B permanent magnet magnetic, ethanol washs 5 times, then with deionized water washing to neutral, 60 DEG C of dry 24h, obtain black powder magnetic nano particle, be designated as Fe
3o
4, its size and magnetic property are with embodiment 1.
(2) preparation of magnetic multistage core@shell structure hydrotalcite supports
Take 1.042g Fe
3o
4nanoparticle is placed in 100mL water ultrasonic disperse 20min.By 2.620gNi (NO
3)
26H
2o and 1.125g Al (NO
3)
39H
2o is dissolved in 100mL water, obtains mixing salt solution.By 0.640g Na
2cO
3be dissolved in 100mL water, as aqueous slkali with 0.800g NaOH.In 25 DEG C of water-baths, slowly drip a small amount of aqueous slkali to Fe
3o
4in suspension, be 10 to pH, stablize 5min.Drip alkali lye subsequently simultaneously and mix saline solution, vigorous stirring, maintenance pH is 10 until salt-mixture liquid dropwises.Be separated this product with Nd-Fe-B permanent magnet magnetic, wash 5 times with deionized water, in 60 DEG C of vacuum drying 24h, obtain magnetic multistage core@shell structure hydrotalcite supports, be designated as Fe
3o
4@NiAl-LDH, its structure and morphology feature and magnetic property are with embodiment 3.
(3) preparation of magnetic multistage core@shell structural nano palladium catalyst
Take the above-mentioned Fe of 1g
3o
4@NiAl-LDH is scattered in 100mL ethanol.5.00mL tetrachloro-palladium acid aqueous solutions of potassium (0.56mol/L) is joined in above-mentioned suspension.Subsequently, add 1mL hydrazine hydrate, after 25 DEG C of reaction 3h, with Nd-Fe-B permanent magnet magnetic separated product, with ethanol and water washing repeatedly to neutral, in 60 DEG C of vacuum drying 24h, obtain black powder magnetic multistage core@shell structural nano palladium catalyst, be designated as Fe
3o
4@[email protected]
0.
Embodiment 7
(1) preparation of magnetic nano particle
Get 2.16g FeCl
36H
2o is dissolved in 80mL ethylene glycol in 40 DEG C of water-baths, obtained stable homogeneous solution; Add 5.76g NaAc3H
2o, is slowly stirred to and dissolves completely, avoids producing bubble; Being transferred to 100mL liner is during polytetrafluoroethylene (PTFE) self-generated pressure bullet holds, 200 DEG C of reaction 8h.Naturally cool to room temperature, be separated with Nd-Fe-B permanent magnet magnetic, ethanol washs 5 times, then with deionized water washing to neutral, 60 DEG C of dry 24h, obtain black powder magnetic nano particle, be designated as Fe
3o
4, its size and magnetic property are with embodiment 1.
(2) preparation of magnetic multistage core@shell structure hydrotalcite supports
Take 1.042g Fe
3o
4nanoparticle is placed in 100mL water ultrasonic disperse 20min.By 2.310gMg (NO
3)
26H
2o and 1.125g Al (NO
3)
39H
2o is dissolved in 100mL water, obtains mixing salt solution.By 0.640gNa
2cO
3be dissolved in 100mL water, as aqueous slkali with 0.800g NaOH.In 25 DEG C of water-baths, slowly drip a small amount of aqueous slkali to Fe
3o
4in suspension, be 10 to pH, stablize 5min.Drip alkali lye subsequently simultaneously and mix saline solution, vigorous stirring, maintenance pH is 10 until salt-mixture liquid dropwises.Be separated this product with Nd-Fe-B permanent magnet magnetic, wash 5 times with deionized water, in 60 DEG C of vacuum drying 24h, obtain magnetic multistage core@shell structure hydrotalcite supports, be designated as Fe
3o
4@MgAl-LDH, its structure and morphology feature and magnetic property are with embodiment 1.
(3) preparation of magnetic multistage core@shell structural nano palladium catalyst
Take the above-mentioned Fe of 1g
3o
4@MgAl-LDH is scattered in 100mL ethanol.1.67mL tetrachloro-palladium acid aqueous solutions of potassium (0.56mol/L) is joined in above-mentioned suspension.Subsequently, add 1mL hydrazine hydrate, after 25 DEG C of reaction 3h, with Nd-Fe-B permanent magnet magnetic separated product, with ethanol and water washing repeatedly to neutral, in 60 DEG C of vacuum drying 24h, obtain black powder magnetic multistage core@shell structural nano palladium catalyst, be designated as Fe
3o
4@[email protected]
0.
Claims (2)
1. a magnetic multistage core shell structure hydrotalcite nano Pd catalyst, is characterized in that: with Fe
3o
4magnetic nano particle is core, with CO
3 2-mgAl, CoAl, NiAl, NiMgAl, CoMgAl and NO of intercalation
3 -the CaMgAl-LDH of intercalation is shell structurre, without part zeroth order Pd nano particle uniform load in the edge of shell hydrotalcite six square piece and staggered position; The chemical general formula of material is Fe
3o
4@MAl-LDH@xPd
0, wherein MAl-LDH is that ab-face is perpendicular to Fe
3o
4surface and the shell hydrotalcite hexagonal nano of interlaced growth is brilliant, Pd
0for be uniformly distributed in MAl-LDH hexagonal nano crystal edge edge and staggered position without part zeroth order Pd nano particle, x is the mass percent load capacity of palladium, and unit is wt%; Wherein, the mass percentage of each component is respectively:
Fe
3O
4：35.5～49.8％；
MAl-LDH：47.7～61.5％；
Pd
0：0.18～3.43％；
Wherein M is one or both divalent metals, can be Mg, Ni, Co, NiMg, CoMg and CaMg; The interlayer anion of shell MAl-LDH can be CO
3 2-or NO
3 -anion;
Monolith particle is of a size of 400 ~ 600 nm, and specific saturation magnetization is 38.6 ~ 54.9emu/g, and specific area is 63 ~ 74m
2/ g; Hydrotalcite shell thickness is 80 ~ 120nm, and single hydrotalcite nano crystalline substance is of a size of 65 ~ 100nm, and thickness is 8 ~ 10nm, and the pore-size between hydrotalcite nano crystalline substance is 55 ~ 110nm; Palladium nanoparticle is of a size of 3.9 ~ 12.1nm.
2. a preparation method for magnetic according to claim 1 multistage core shell structure hydrotalcite nano Pd catalyst, is characterized in that, comprises following three steps:
(1) preparation of magnetic nano particle
Surfactant-free solvent-thermal method is adopted to prepare ferroferric oxide magnetic nano grain;
Take 2.16 g FeCl
36H
2o is dissolved in 80mL ethylene glycol in 30 ~ 50 DEG C of water-baths, obtained stable homogeneous orange solution, and concentration is 0.1mol/L; Add 5.76 g NaAc3H
2o, is slowly stirred to and dissolves completely, avoids producing bubble, NaAc3H
2o and FeCl
36H
2the mol ratio of O is 5.29; Being transferred to 100mL liner is in the self-generated pressure bullet appearance of polytetrafluoroethylene (PTFE), in 200 DEG C of reaction 8h; Naturally cool to room temperature, adopt Nd-Fe-B permanent magnet magnetic to be separated, wash 5 times respectively by ethanol and deionized water, in 60 DEG C of drying 24 ~ 48h, obtain black powder magnetic nano particle, be designated as Fe
3o
4;
(2) preparation of magnetic multistage core@shell structure hydrotalcite supports
The two coprecipitations of dripping improved are adopted to prepare magnetic multistage core@shell structure hydrotalcite supports;
The first step: M pressed by divalent metal salt and aluminium salt
2+/ Al
3+the molar concentration rate of=3, is made into mixing salt solution with water; Another preparation contains NaOH and Na
2cO
3aqueous slkali (in magnetic CaMgAl-LDH system, the solute of aqueous slkali only has NaOH; Take 1.042g Fe
3o
4magnetic nano particle, with the preparation of surfactant-free solvent-thermal method, size is about 400nm, and in 100mL water, ultrasonic 20min forms suspension, and wherein the molal quantity ratio of hydrotalcite laminate divalent metal element and magnetic core Fe element is 0.25 ~ 0.75;
Wherein M is one or more divalent metals, is Mg, Ni, Co, NiMg, CoMg and CaMg;
Second step: by Fe
3o
4suspension is placed in 500mL four-hole boiling flask; mechanical agitation; magnetic CaMgAl-LDH system need be protected with nitrogen atmosphere, under ice-water bath magnetic CoAl or CoMgAl-LDH system or room temperature magnetism MgAl, NiAl, NiMgAl and CaMgAl-LDH system, with mixed ammonium/alkali solutions by Fe
3o
4the pH value of suspension is slowly adjusted to required numerical value, and for magnetic MgAl, NiAl, CoAl, NiMgAl and CoMgAl-LDH system, precipitation pH is adjusted to 10; For magnetic CaMgAl-LDH system, precipitation pH is adjusted to 11.5, stablizes 5 ~ 10min; Mixing salt solution and mixed ammonium/alkali solutions are slowly dripped wherein subsequently simultaneously, keep slurries pH constant, after mixing salt solution drips off, slurries continue to keep rapid stirring 5min;
3rd step: be separated black solid product with Nd-Fe-B permanent magnet magnetic, with deionized water washing repeatedly to supernatant pH in neutral, in 60 DEG C of drying 24 ~ 48h, magnetic CaMgAl-LDH system needs vacuum drying, grinding obtains black powder magnetic multistage core@shell structure hydrotalcite supports, is designated as Fe
3o
4@MAl-LDH;
(3) preparation of magnetic multistage core@shell structure hydrotalcite loaded nanometer palladium catalyst
Adopt immersion reduction method load zeroth order palladium nanoparticle in above-mentioned magnetic multistage core@shell structure hydrotalcite supports;
Take the above-mentioned magnetic of 1g multistage core@shell structure hydrotalcite supports Fe
3o
4@MAl-LDH is scattered in 100mL ethanol, mechanical agitation, and 0.17 ~ 8.33mL tetrachloro-palladium acid aqueous solutions of potassium 0.56mol/L is joined above-mentioned suspension; Subsequently, add 1mL hydrazine hydrate, room temperature reduction 3h at 25 DEG C; Be separated to obtain magnetic black solid with Nd-Fe-B permanent magnet, wash repeatedly to neutral with ethanol and deionized water, in 60 DEG C of vacuum drying 24 ~ 48h, grinding obtains black powder magnetic multistage core@shell structural nano palladium catalyst, is designated as Fe
3o
4@MAl-LDH@xPd
0, wherein, x is the mass percent load capacity of palladium, and unit is wt%, and scope is 0.18 ~ 3.43.
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