CN102688760B - Fe3O4/CuO/pSiO2 catalyst and preparation method thereof - Google Patents

Fe3O4/CuO/pSiO2 catalyst and preparation method thereof Download PDF

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CN102688760B
CN102688760B CN201210186971.0A CN201210186971A CN102688760B CN 102688760 B CN102688760 B CN 102688760B CN 201210186971 A CN201210186971 A CN 201210186971A CN 102688760 B CN102688760 B CN 102688760B
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王戈
张晓伟
黄铌
郭万春
高鸿毅
杨穆
王倩
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University of Science and Technology Beijing USTB
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Abstract

The invention relates to a Fe3O4/CuO/pSiO2 (porous silica) catalyst, a preparation method thereof and application thereof in olefin epoxidation reaction. The preparation method comprises the following processes of: obtaining Fe3O4 microspheres serving as magnetic cores by adopting a co-precipitation method, and modifying the surfaces of the Fe3O4 microspheres by using polyvinyl pyrrolidone (PVP) in order to improve the adsorption effect of the surfaces of the Fe3O4 microspheres on metal cations; coating a CuO nano shell layer on the surfaces of the Fe3O4 microspheres by using copper acetate as a copper source through hydrothermal synthesis; and finally, coating the porous silicon dioxide shell layer by using cetyl trimethyl ammonium bromide (CTAB) as a surfactant and using ethyl orthosilicate as a silicon source, and thus obtaining a composite catalytic material with a magnetic Fe3O4/CuO/pSiO2 core-shell structure. The catalytic performance of the composite material is researched by respectively using epoxidation reaction of styrene and cyclooctene as probe reaction, and the results prove that the catalytic material has high reaction activity and selectivity, and the catalytic material is easy to separate and recover by introducing the magnetic ores; and the catalytic material has a good circulating effect, still can keep excellent catalytic performance by dozens of times of circulation, and has a great application prospect.

Description

Fe 3o 4/ CuO/pSiO 2catalysts and its preparation method
Technical field
The invention belongs to magnetic Nano catalysis material field, relate to a kind of Fe with nucleocapsid structure 3o 4/ CuO/pSiO 2the preparation of magnetic coupling catalysis material and the application in epoxidation reaction of olefines thereof.
Background technology
Epoxidation reaction of olefines is the important catalytic oxidation of a class, its product " olefin epoxide " is described as " organic intermediate of most worthy ", its downstream product is widely used in the various fields such as petrochemical industry, Polymer Synthesizing, organic synthesis, fine chemistry industry, biological medicine, have wide range of applications, the market demand is large, can produce huge economic benefit.But its production process must rely on catalysis material, realizing protection of the environment, simplify technique, Reaction time shorten, raising output, a series of objects such as reduce production costs.Therefore, alkene epoxidation is the research field receiving much concern with the preparation of catalyst with innovation always.
Because existing, homogeneous catalyst is difficult for from reaction system separation, the major defect that is difficult to recycle, and in recent years, heterogeneous catalyst has obtained significant progress with its more segregative advantage.Wherein, magnetic catalysis material with its unique magnetic response function, greatly reduces separating difficulty again, only need can realize the rapidly and efficiently recovery of catalysis material by externally-applied magnetic field, greatly improves the service life cycle of catalyst, effectively reduces manufacture of materials cost.Thereby the research of magnetic catalysis material has become the focus that catalytic field is new.
Cupric oxide is the important transition metal oxide of a class, at aspects such as catalysis, gas sensor, solar energy conversion and high-temperature superconductors, has a wide range of applications.At alkene epoxidation catalytic field, because cupric oxide itself has narrower band gap, catalytic activity is higher, and price is low, pollutes littlely, thereby has caused that researcher more and more pays close attention to.The people such as Linping Xu ( chem. Mater. 2009, 21,1253 – 1259) adopt circumfluence method to prepare the CuO cluster of sea urchin shape, it has certain catalytic effect (optimal result: 1 mmol alkene, reaction 24h, wherein, the conversion ratio of cyclo-octene is 64.3%, is selectively 100%) to epoxidation reaction of olefines.The people such as Guohong Qiu ( j. Phys. Chem. C 2012,116, 468 – 477) prepared the cupric oxide of two kinds of different-shapes of spherical and colored shape, the 1 mmol alkene of take is substrate, reaction 24h, and cinnamic conversion ratio is 100%, selectively only has 45%.The catalytic reaction time of above two kinds of researchs is longer, and the difficult recovery of catalyst, and dispersiveness and circulating effect are all poor.Chaoqiu Chen research group ( j. Mater. Chem., 2011, 21,5774 – 5779) prepared the coating mesoporous SiO in CuO outside 2hud typed catalyst, the 1 mmol alkene of take is equally substrate, reaction 8h, the conversion ratio of cyclo-octene and be selectively respectively 66.5% and 100%; Reaction 2h, cinnamic conversion ratio and be selectively respectively 88.6% and 61.2%.Result shows, the catalytic activity of catalyst and circulating effect have had significant improvement.But the recovery of catalyst need to be by traditional isolation technics such as filtering, centrifugal, consuming time longer, for nanometer materials, the equipment needing is more complicated, and separating difficulty increases, and catalyst loss is also more serious.
In sum, magnetic material, in the function aspect rapidly and efficiently separated recovery and the effective combination of the advantage of composite on catalytic performance, can be produced to good advantage coupling effect.
Summary of the invention
For above-mentioned situation, the object of the invention is to magnetic responsiveness and CuO/SiO in conjunction with magnetic material 2the advantage of the aspects such as the catalytic performance of material, provides a kind of hud typed Fe 3o 4/ CuO/pSiO 2(porous silica) magnetic coupling catalysis material and preparation method thereof, and using the epoxidation reaction of styrene and cyclo-octene and as probe reaction, the catalytic performance of this new catalyst is inquired into.
The invention provides a kind of Fe 3o 4/ CuO/pSiO 2catalyst, wherein " p " represents porous, " pSiO 2" expression porous SiO 2; Described Fe 3o 4/ CuO/pSiO 2catalyst is with the Fe through finishing 3o 4as magnetic function core, CuO is as active component, porous SiO 2core-shell structure magnetic composite catalyst as protective layer.
Above-mentioned Fe 3o 4/ CuO/pSiO 2the preparation method of catalyst, is characterized in that comprising following preparation process:
(1) described Fe 3o 4the preparation of magnetic microsphere adopts coprecipitation, and its concrete preparation process is: by a certain amount of FeCl 36H 2o is dissolved in deionized water, and making solution concentration is 0.16 ~ 0.24mol/L, stirs and continue to pass into high pure nitrogen (until obtain Fe under room temperature 3o 4magnetic microsphere), stir speed (S.S.) 200 ~ 350rpm, mixing time 10 ~ 40min, adds appropriate FeCl 24H 2o, continues reaction 20 ~ 60min; Be warming up to 80 ℃, add rapidly a certain amount of NH 3h 2o; For increasing its surface hydrophilicity, dropwise inject citric acid solution; After dropwising, reaction 45 ~ 90min; Vacuum drying, obtains Fe 3o 4magnetic microsphere; Wherein, FeCl 24H 2o, FeCl 36H 2the mol ratio of O, ammoniacal liquor and citric acid is about 1:2:200:2;
Described Fe 3o 4the finishing of magnetic microsphere is to using polyvinylpyrrolidone (PVP) as surfactant; Concrete operations are: first, take a certain amount of PVP(molecular weight 58000) be dissolved in deionized water preparation PVP(molecular weight 58000) solution a; Secondly, add the appropriate above-mentioned Fe making 3o 4magnetic microsphere, Fe 3o 4with the mol ratio of PVP be 42.9:1 ~ 53.6:1; Ultrasonic dispersion, is then placed in shaking bath and reacts at a certain temperature; Finally wash and carry out room temperature vacuum drying, obtaining the Fe of surface modification 3o 4magnetic microsphere;
(2) load of described CuO nanoshells, concrete preparation process is: take a certain amount of Schweinfurt green (C 4h 6cuO 4h 2o), in appropriate absolute ethyl alcohol, preparation obtains the ethanolic solution of Schweinfurt green, ultrasonic be dispersed to entirely molten; In solution, add appropriate urea again, the mol ratio of Schweinfurt green and urea is 0.4:1 ~ 0.6:1, continues ultrasonic agitation to all dissolving; Then add a certain amount of Fe after PVP modifies 3o 4and ultrasonic be dispersed to entirely molten, Schweinfurt green and Fe 3o 4(PVP) mass ratio is 4:1 ~ 12:1; Solution is transferred in reactor and carries out, after hydro-thermal reaction, with deionized water and absolute ethyl alcohol, washing, finally carry out room temperature vacuum drying and obtain Fe 3o 4/ CuO magnetic microsphere;
(3) described porous SiO 2being coated of shell, concrete operations are: the mixed solution b of preparation deionized water and absolute ethyl alcohol; Take appropriate softex kw (CTAB) and be dissolved in above-mentioned solution b, ultrasonic be dispersed to entirely molten; Add the Fe having prepared 3o 4/ CuO magnetic microsphere, Fe 3o 4the mass ratio of/CuO and CTAB is 2.7:1 ~ 5.0:1, at 20 ~ 30 ℃ of temperature, stirs 1 ~ 2h; Add proper ammonia (containing ammonia 25%～28%), dropwise drip a certain amount of ethyl orthosilicate (TEOS), the volume ratio of ammoniacal liquor, TEOS and mixed solution b is 0.28 ~ 0.8:0.17 ~ 0.26:100, continues to stir 6 ~ 15h, washs and remove surfactant.Obtain Fe 3o 4/ CuO/pSiO 2magnetic coupling catalyst.
The concentration that adds citric acid solution in described step (1) is 1.0 ~ 1.2mol/L; The described NH adding 3h 2o is containing ammonia 25 ~ 28%; The described PVP(molecular weight 58000 making) concentration of solution a is 3.44 ~ 4.31mol/L.Further, in described step (1), the time of ultrasonic dispersion is 10 ~ 30min, and the temperature and time reacting in shaking bath is respectively 25 ~ 35 ℃ and 20 ~ 30h.
In described preparation process 1, adopt coprecipitation to synthesize Fe 3o 4microballoon, object is the magnetic core that provides less, thereby effectively controls the whole particle diameter of catalyst, to keep higher catalytic activity when introducing magnetic recovery function; Add a certain amount of citric acid, in order to increase Fe 3o 4surface hydrophilicity, thereby improve its degree of scatter in water; Adopt polyvinylpyrrolidone to Fe 3o 4microballoon carries out finishing, and object is to improve magnetic core and Cu 2+interaction, promote the effectively coated of CuO shell.
In described step (2), the concentration of the ethanolic solution of preparation Schweinfurt green is 0.010 ~ 0.015mol/L; The temperature of described hydro-thermal reaction is 160 ~ 180 ℃, and the reaction time is 40 ~ 80min.In described preparation process 2, Dichlorodiphenyl Acetate copper and Fe 3o 4(PVP) addition is controlled, be mainly because: if Fe 3o 4(PVP) add very few, the excessive independent balling-up of Schweinfurt green meeting, do not there is magnetic function; If Fe 3o 4(PVP) add too much, excessive Fe 3o 4(PVP) can, in reactor bottom sedimentation, can not realize the effectively coated of CuO shell.Therefore, control Schweinfurt green and Fe 3o 4(PVP), when mass ratio is 4:1 ~ 12:1, CuO is better in the surface coated effect of magnetic core.
Described in described step (3), in the mixed solution b of deionized water and absolute ethyl alcohol, the volume ratio of deionized water and absolute ethyl alcohol is 1.3:1 ~ 1.5:1, the concentration of described softex kw (CTAB) in mixed solution b is 0.05 ~ 0.08mol/L, Fe 3o 4the mass ratio of/CuO and CTAB is 2.7:1 ~ 5.0:1, and the volume ratio that adds ammoniacal liquor, ethyl orthosilicate and mixed solution b is 0.28 ~ 0.8:0.17 ~ 0.26:100.
The removal of surfactant described in described step (3) can adopt fast ion exchange method, and the ethanolic solution of preparation ammonium nitrate is as extractant, and its concentration is 0.18 ~ 0.25mol/L, finally washs and room temperature vacuum drying; Or the removal of the high-temperature calcination under employing nitrogen protection surfactant, temperature is controlled at 450 ~ 550 ℃, calcining 3 ~ 6h.
In described preparation process 3, the volume ratio of deionized water and absolute ethyl alcohol is controlled at 1.3:1 ~ 1.5:1, and Fe 3o 4the mass ratio of/CuO and CTAB is set as 2.7:1 ~ 5.0:1, is to realize porous SiO 2the crucial preparation condition that shell is effectively coated; Adopt fast ion exchange technology to remove surfactant, mainly consider that its gentle reaction condition is less on the impact of magnetic core, and the reaction time is short; Adopt the high-temperature calcination under nitrogen protection to remove surfactant, easy to operation, and removal of surfactant is complete.
Fe of the present invention 3o 4/ CuO/pSiO 2catalyst is mainly used in catalytic oxidation epoxidation reaction of olefines, and can by Magnetic Isolation, realize the quick recovery of catalyst, reaches the good effect that recycles.Being set as of described epoxidation reaction of olefines condition: substrate (alkene): 0.3mmol; Fe 3o 4/ CuO/pSiO 2catalyst: 10 ~ 30mg; Solvent: acetonitrile, 5ml ~ 10ml; Oxygen source: TBHP, 0.6 ~ 1.5ml; Reaction temperature: 60 ~ 75 ℃; Reaction time: 9h; Catalytic result: cinnamic conversion ratio approaches 100%, selectively the reaching more than 80% of Styryl oxide; The conversion ratio of cyclo-octene is in 70% left and right, epoxide ring octane selectively approach 100%; Through tens of circulation catalytic effects, still can keep.
In sum, the invention provides a kind of hud typed Fe 3o 4/ CuO/pSiO 2the preparation of magnetic coupling catalysis material and for the catalytic performance research of epoxidation reaction of olefines, its feature is: on the one hand, adopt Fe 3o 4microballoon is as magnetic core, can realize rapidly and efficiently separated recovery of catalysis material, effectively reduces catalyst loss, improves cyclic utilization rate, extending catalyst service life, greatly reduces its production and maintenance cost; On the other hand, to small particle diameter Fe 3o 4microballoon carries out finishing, can realize green inexpensive CuO activated centre and porous SiO 2effectively being coated of shell, had both completed the introducing of magnetic response function, had guaranteed that again the high activity of catalyst is with selective.
accompanying drawing explanation
Hud typed Fe prepared by accompanying drawing 1 the present invention 3o 4/ CuO/pSiO 2the high-resolution-ration transmission electric-lens figure of magnetic coupling catalysis material.
the specific embodiment
Below by embodiment, technical scheme of the present invention is further described.
Embodiment 1:
(1) Fe 3o 4the preparation of magnetic microsphere: take a certain amount of FeCl 36H 2o is dissolved in deionized water, and concentration is 0.24mol/L, and under room temperature, stir and continue to pass into high pure nitrogen, stir speed (S.S.) 280rpm, mixing time 40min, adds appropriate FeCl 24H 2o, and continue reaction 30min; Be warming up to 80 ℃, add rapidly a certain amount of NH 3h 2o(is containing ammonia 25 ~ 28%), for increasing its surface hydrophilicity, dropwise inject the citric acid solution of 1.2mol/L; After dropwising, reaction 60min; Vacuum drying, obtains Fe 3o 4magnetic microsphere.Wherein, FeCl 24H 2o, FeCl 36H 2the mol ratio of O, ammoniacal liquor and citric acid is about 1:2:200:2.
Take a certain amount of PVP(molecular weight 58000) be dissolved in deionized water the solution that compound concentration is 3.6mol/L; Secondly, add the appropriate above-mentioned Fe making 3o 4magnetic microsphere, ultrasonic dispersion 30min, Fe 3o 4with the mol ratio of PVP be 50:1; Then be placed in shaking bath, 30 ℃ of reaction 24h; Finally wash and carry out room temperature vacuum drying, obtaining the Fe of surface modification 3o 4magnetic microsphere.
(2) load of CuO nanoshells: take a certain amount of Schweinfurt green (C 4h 6cuO 4h 2o) in appropriate absolute ethyl alcohol, the ethanolic solution of preparation 0.012mol/L Schweinfurt green, ultrasonic be dispersed to entirely molten; In solution, add appropriate urea again, the mol ratio of Schweinfurt green and urea is 0.4:1, continues ultrasonic agitation to all dissolving; Then add a certain amount of Fe after PVP modifies 3o 4and ultrasonic be dispersed to entirely molten, Schweinfurt green and Fe 3o 4(PVP) mass ratio is 8:1; Solution is transferred in reactor, and 180 ℃ of reaction 70min, wash with deionized water and absolute ethyl alcohol, finally carry out room temperature vacuum drying, obtain Fe 3o 4/ CuO magnetic microsphere.
(3) porous SiO 2being coated of shell: the mixed solution of preparation deionized water and absolute ethyl alcohol, the volume ratio of deionized water and absolute ethyl alcohol is 1.5:1; Take appropriate softex kw (CTAB) and be dissolved in above-mentioned solution, be ultrasonicly dispersed to entirely moltenly, the concentration of CTAB in mixed solution is 0.08mol/L; Add the Fe having prepared 3o 4/ CuO magnetic microsphere, Fe 3o 4the mass ratio of/CuO and CTAB is 3.0:1, at 25 ℃ of temperature, stirs 1h; Add proper ammonia (containing ammonia 25%～28%), dropwise drip a certain amount of ethyl orthosilicate (TEOS), the volume ratio of ammoniacal liquor, TEOS and mixed solution is 0.4:0.18:100, continues to stir 12h, washing; The removal of surfactant adopts fast ion exchange method, prepares the ethanolic solution of ammonium nitrate as extractant, and its concentration is 0.20mol/L; Finally wash and room temperature vacuum drying, obtain Fe 3o 4/ CuO/pSiO 2magnetic coupling catalyst.
(4) epoxidation reaction of olefines condition: styrene: 0.3mmol, cyclo-octene: 0.3mmol; The catalyst making in the present embodiment: 10mg; Solvent: acetonitrile, 5ml; Oxygen source: TBHP, 0.75ml; Reaction temperature: 70 ℃; Reaction time: 9h; Loop test: 8 times.
Under the epoxidation reaction of olefines condition of setting in the present invention, adopt GC-MS to carry out catalytic activity test, to the cinnamic catalytic effect of 0.3mmol, be: cinnamic conversion ratio is 99.2%, Styryl oxide be selectively 88.4%.Circulate after 8 times, cinnamic conversion ratio is 99.0%, Styryl oxide be selectively 88.3%.To the catalytic effect of 0.3mmol cyclo-octene, be: the conversion ratio of cyclo-octene is 72.4%, epoxide ring octane be selectively 99.8%.Circulate after 8 times, the conversion ratio of cyclo-octene is 72.0%, epoxide ring octane be selectively 99.7%.
Embodiment 2:
(1) Fe 3o 4the preparation of magnetic microsphere: take a certain amount of FeCl 36H 2o is dissolved in deionized water, and concentration is 0.20mol/L, and under room temperature, stir and continue to pass into high pure nitrogen, stir speed (S.S.) 300rpm, mixing time 30min, adds appropriate FeCl 24H 2o, and continue reaction 40min; Be warming up to 80 ℃, add rapidly a certain amount of NH 3h 2o(is containing ammonia 25 ~ 28%), for increasing its surface hydrophilicity, dropwise inject the citric acid solution of 1.1mol/L; After dropwising, reaction 70min; Vacuum drying, obtains Fe 3o 4magnetic microsphere.Wherein, FeCl 24H 2o, FeCl 36H 2the mol ratio of O, ammoniacal liquor and citric acid is about 1:2:200:2.
Take a certain amount of PVP(molecular weight 58000) be dissolved in deionized water the solution that compound concentration is 4.0mol/L; Secondly, add the appropriate above-mentioned Fe making 3o 4magnetic microsphere, ultrasonic dispersion 20min, Fe 3o 4with the mol ratio of PVP be 46:1; Then be placed in shaking bath, 25 ℃ of reaction 30h; Finally wash and carry out room temperature vacuum drying, obtaining the Fe of surface modification 3o 4magnetic microsphere.
(2) load of CuO nanoshells: take a certain amount of Schweinfurt green (C 4h 6cuO 4h 2o) in appropriate absolute ethyl alcohol, the ethanolic solution of preparation 0.015mol/L Schweinfurt green, ultrasonic be dispersed to entirely molten; In solution, add appropriate urea again, the mol ratio of Schweinfurt green and urea is 0.5:1, continues ultrasonic agitation to all dissolving; Then add a certain amount of Fe after PVP modifies 3o 4and ultrasonic be dispersed to entirely molten, Schweinfurt green and Fe 3o 4(PVP) mass ratio is 6:1; Solution is transferred in reactor, and 170 ℃ of reaction 90min, wash with deionized water and absolute ethyl alcohol, finally carry out room temperature vacuum drying, obtain Fe 3o 4/ CuO magnetic microsphere.
(3) porous SiO 2being coated of shell: the mixed solution of preparation deionized water and absolute ethyl alcohol, the volume ratio of deionized water and absolute ethyl alcohol is 1.4:1; Take appropriate softex kw (CTAB) and be dissolved in above-mentioned solution, be ultrasonicly dispersed to entirely moltenly, the concentration of CTAB in mixed solution is 0.06mol/L; Add the Fe having prepared 3o 4/ CuO magnetic microsphere, Fe 3o 4the mass ratio of/CuO and CTAB is 4.0:1, at 30 ℃ of temperature, stirs 1h; Add proper ammonia (containing ammonia 25%～28%), dropwise drip a certain amount of ethyl orthosilicate (TEOS), the volume ratio of ammoniacal liquor, TEOS and mixed solution is 0.6:0.20:100, continues to stir 15h, washing; The removal of surfactant adopts fast ion exchange method, prepares the ethanolic solution of ammonium nitrate as extractant, and its concentration is 0.18mol/L; Finally wash and room temperature vacuum drying, obtain Fe 3o 4/ CuO/pSiO 2magnetic coupling catalyst.
(4) epoxidation reaction of olefines condition: styrene: 0.3mmol, cyclo-octene: 0.3mmol; Catalyst: 15mg; Solvent: acetonitrile, 10ml; Oxygen source: TBHP, 0.60ml; Reaction temperature: 70 ℃; Reaction time: 9h; Loop test: 10 times.
Under the epoxidation reaction of olefines condition of setting in the present invention, adopt GC-MS to carry out catalytic activity test, to the cinnamic catalytic effect of 0.3mmol, be: cinnamic conversion ratio is 99.5%, Styryl oxide be selectively 86.2%.Circulate after 10 times, cinnamic conversion ratio is 99.3%, Styryl oxide be selectively 85.7%.To the catalytic effect of 0.3mmol cyclo-octene, be: the conversion ratio of cyclo-octene is 70.5%, epoxide ring octane be selectively 99.9%.Circulate after 10 times, the conversion ratio of cyclo-octene is 70.3%, epoxide ring octane be selectively 99.7%.
Embodiment 3:
(1) Fe 3o 4the preparation of magnetic microsphere: take a certain amount of FeCl 36H 2o is dissolved in deionized water, and concentration is 0.22mol/L, and under room temperature, stir and continue to pass into high pure nitrogen, stir speed (S.S.) 310rpm, mixing time 25min, adds appropriate FeCl 24H 2o, and continue reaction 25min; Be warming up to 80 ℃, add rapidly a certain amount of NH 3h 2o(is containing ammonia 25 ~ 28%), for increasing its surface hydrophilicity, dropwise inject the citric acid solution of 1.2mol/L; After dropwising, reaction 90min; Vacuum drying, obtains Fe 3o 4magnetic microsphere.Wherein, FeCl 24H 2o, FeCl 36H 2the mol ratio of O, ammoniacal liquor and citric acid is about 1:2:200:2.
Take a certain amount of PVP(molecular weight 58000) be dissolved in deionized water the solution that compound concentration is 3.8mol/L; Secondly, add the appropriate above-mentioned Fe making 3o 4magnetic microsphere, ultrasonic dispersion 15min, Fe 3o 4with the mol ratio of PVP be 48:1; Then be placed in shaking bath, 25 ℃ of reaction 26h; Finally wash and carry out room temperature vacuum drying, obtaining the Fe of surface modification 3o 4magnetic microsphere.
(2) load of CuO nanoshells: take a certain amount of Schweinfurt green (C 4h 6cuO 4h 2o) in appropriate absolute ethyl alcohol, the ethanolic solution of preparation 0.010mol/L Schweinfurt green, ultrasonic be dispersed to entirely molten; In solution, add appropriate urea again, the mol ratio of Schweinfurt green and urea is 0.45:1, continues ultrasonic agitation to all dissolving; Then add a certain amount of Fe after PVP modifies 3o 4and ultrasonic be dispersed to entirely molten, Schweinfurt green and Fe 3o 4(PVP) mass ratio is 10:1; Solution is transferred in reactor, and 180 ℃ of reaction 65min, wash with deionized water and absolute ethyl alcohol, finally carry out room temperature vacuum drying, obtain Fe 3o 4/ CuO magnetic microsphere.
(3) porous SiO 2being coated of shell: the mixed solution of preparation deionized water and absolute ethyl alcohol, the volume ratio of deionized water and absolute ethyl alcohol is 1.33:1; Take appropriate softex kw (CTAB) and be dissolved in above-mentioned solution, be ultrasonicly dispersed to entirely moltenly, the concentration of CTAB in mixed solution is 0.05mol/L; Add the Fe having prepared 3o 4/ CuO magnetic microsphere, Fe 3o 4the mass ratio of/CuO magnetic microsphere and CTAB is 3.6:1, at 25 ℃ of temperature, stirs 1h; Add proper ammonia (containing ammonia 25%～28%), dropwise drip a certain amount of ethyl orthosilicate (TEOS), the volume ratio of ammoniacal liquor, TEOS and mixed solution is 0.5:0.24:100, continues to stir 10h, washing, vacuum drying; Finally adopt high-temperature calcination under nitrogen protection to remove surfactant, calcine 4h at 500 ℃, obtain Fe 3o 4/ CuO/pSiO 2magnetic coupling catalyst.
(4) epoxidation reaction of olefines condition: styrene: 0.3mmol, cyclo-octene: 0.3mmol; Catalyst: 20mg; Solvent: acetonitrile, 7ml; Oxygen source: TBHP, 0.80ml; Reaction temperature: 75 ℃; Reaction time: 9h; Loop test: 12 times.
Under the epoxidation reaction of olefines condition of setting in the present invention, adopt GC-MS to carry out catalytic activity test, to the cinnamic catalytic effect of 0.3mmol, be: cinnamic conversion ratio is 99.9%, Styryl oxide be selectively 86.0%.Circulate after 12 times, cinnamic conversion ratio is 99.2%, Styryl oxide be selectively 85.5%.To the catalytic effect of 0.3mmol cyclo-octene, be: the conversion ratio of cyclo-octene is 67.3%, epoxide ring octane be selectively 99.5%.Circulate after 12 times, the conversion ratio of cyclo-octene is 65.5%, epoxide ring octane be selectively 99.3%.
Embodiment 4:
(1) Fe 3o 4the preparation of magnetic microsphere: take a certain amount of FeCl 36H 2o is dissolved in deionized water, and concentration is 0.18mol/L, and under room temperature, stir and continue to pass into high pure nitrogen, stir speed (S.S.) 290rpm, mixing time 35min, adds appropriate FeCl 24H 2o, and continue reaction 45min; Be warming up to 80 ℃, add rapidly a certain amount of NH 3h 2o(is containing ammonia 25 ~ 28%), for increasing its surface hydrophilicity, dropwise inject the citric acid solution of 1.2mol/L; After dropwising, reaction 70min; Vacuum drying, obtains Fe 3o 4magnetic microsphere.Wherein, FeCl 24H 2o, FeCl 36H 2the mol ratio of O, ammoniacal liquor and citric acid is about 1:2:200:2.
Take a certain amount of PVP(molecular weight 58000) be dissolved in deionized water the solution that compound concentration is 4.3mol/L; Secondly, add the appropriate above-mentioned Fe making 3o 4magnetic microsphere, ultrasonic dispersion 18min, Fe 3o 4with the mol ratio of PVP be 53:1; Then be placed in shaking bath, 30 ℃ of reaction 20h; Finally wash and carry out room temperature vacuum drying, obtaining the Fe of surface modification 3o 4magnetic microsphere.
(2) load of CuO nanoshells: take a certain amount of Schweinfurt green (C 4h 6cuO 4h 2o) in appropriate absolute ethyl alcohol, the ethanolic solution of preparation 0.013mol/L Schweinfurt green, ultrasonic be dispersed to entirely molten; In solution, add appropriate urea again, the mol ratio of Schweinfurt green and urea is 0.52:1, continues ultrasonic agitation to all dissolving; Then add a certain amount of Fe after PVP modifies 3o 4and ultrasonic be dispersed to entirely molten, Schweinfurt green and Fe 3o 4(PVP) mass ratio is 9:1; Solution is transferred in reactor, and 175 ℃ of reaction 70min, wash with deionized water and absolute ethyl alcohol, finally carry out room temperature vacuum drying, obtain Fe 3o 4/ CuO magnetic microsphere.
(3) porous SiO 2being coated of shell: the mixed solution of preparation deionized water and absolute ethyl alcohol, the volume ratio of deionized water and absolute ethyl alcohol is 1.5:1; Take appropriate softex kw (CTAB) and be dissolved in above-mentioned solution, be ultrasonicly dispersed to entirely moltenly, the concentration of CTAB in mixed solution is 0.07mol/L; Add the Fe having prepared 3o 4/ CuO magnetic microsphere, Fe 3o 4the mass ratio of/CuO and CTAB is 4.0:1, at 25 ℃ of temperature, stirs 1.5h; Add proper ammonia (containing ammonia 25%～28%), dropwise drip a certain amount of ethyl orthosilicate (TEOS), the volume ratio of ammoniacal liquor, TEOS and mixed solution is 0.7:0.2:100, continues to stir 8h, washing, vacuum drying; Finally adopt high-temperature calcination under nitrogen protection to remove surfactant, calcine 3h at 550 ℃, obtain Fe 3o 4/ CuO/pSiO 2magnetic coupling catalyst.
(4) epoxidation reaction of olefines condition: styrene: 0.3mmol, cyclo-octene: 0.3mmol; Catalyst: 25mg; Solvent: acetonitrile, 8ml; Oxygen source: TBHP, 0.80ml; Reaction temperature: 70 ℃; Reaction time: 9h; Loop test: 15 times.
Under the epoxidation reaction of olefines condition of setting in the present invention, adopt GC-MS to carry out catalytic activity test, to the cinnamic catalytic effect of 0.3mmol, be: cinnamic conversion ratio is 99.7%, Styryl oxide be selectively 84.9%.Circulate after 15 times, cinnamic conversion ratio is 99.3%, Styryl oxide be selectively 83.6%.To the catalytic effect of 0.3mmol cyclo-octene, be: the conversion ratio of cyclo-octene is 68.2%, epoxide ring octane be selectively 99.7%.Circulate after 15 times, the conversion ratio of cyclo-octene is 63.9%, epoxide ring octane be selectively 99.3%.

Claims (8)

1. a Fe 3o 4/ CuO/pSiO 2catalyst, is characterized in that: described Fe 3o 4/ CuO/pSiO 2catalyst is with the Fe through finishing 3o 4as magnetic function core, CuO is as active component, porous SiO 2core-shell structure magnetic composite catalyst as protective layer; Described Fe 3o 4/ CuO/pSiO 2the preparation method of catalyst comprises following preparation process:
(1) Fe 3o 4the preparation of magnetic microsphere adopts coprecipitation, and its concrete preparation process is: by a certain amount of FeCl 36H 2o is dissolved in deionized water, and making solution concentration is 0.16～0.24mol/L, and under room temperature, stir and continue to pass into high pure nitrogen, stir speed (S.S.) 200～350rpm, mixing time 10～40min, adds appropriate FeCl 24H 2o, continues reaction 20～60min; Be warming up to 80 ℃, add rapidly a certain amount of NH 3h 2o; For increasing its surface hydrophilicity, dropwise inject citric acid solution; After dropwising, reaction 45～90min; Vacuum drying, obtains Fe 3o 4magnetic microsphere; Wherein, FeCl 24H 2o, FeCl 36H 2the mol ratio of O, ammoniacal liquor and citric acid is 1:2:200:2; Described Fe 3o 4the finishing of magnetic microsphere is to using polyvinylpyrrolidone PVP as surfactant; Concrete operations are: first, take a certain amount of molecular weight and be 58000 PVP and be dissolved in deionized water, the PVP solution a that preparation molecular weight is 58000; Secondly, add the appropriate above-mentioned Fe making 3o 4magnetic microsphere, Fe 3o 4with the mol ratio of PVP be 42.9:1～53.6:1; Ultrasonic dispersion, is then placed in shaking bath and reacts at a certain temperature; Finally wash and carry out room temperature vacuum drying, obtaining the Fe of surface modification 3o 4magnetic microsphere;
(2) load of CuO nanoshells, concrete preparation process is: take a certain amount of Schweinfurt green in appropriate absolute ethyl alcohol, preparation obtains the ethanolic solution of Schweinfurt green, ultrasonic be dispersed to entirely molten; In solution, add appropriate urea again, the mol ratio of Schweinfurt green and urea is 0.4:1～0.6:1, continues ultrasonic agitation to all dissolving; Then add a certain amount of Fe after PVP modifies 3o 4and ultrasonic be dispersed to entirely molten, the Fe modifying through PVP obtaining in Schweinfurt green and step (1) 3o 4mass ratio be 4:1～12:1; Solution is transferred in reactor and carries out, after hydro-thermal reaction, with deionized water and absolute ethyl alcohol, washing, finally carry out room temperature vacuum drying and obtain Fe 3o 4/ CuO magnetic microsphere;
(3) porous SiO 2being coated of shell, concrete operations are: the mixed solution b of preparation deionized water and absolute ethyl alcohol; Take appropriate softex kw CTAB and be dissolved in above-mentioned solution b, ultrasonic be dispersed to entirely molten; Add the Fe having prepared 3o 4/ CuO magnetic microsphere, Fe 3o 4the mass ratio of/CuO and CTAB is 2.7:1～5.0:1, at 20～30 ℃ of temperature, stirs 1～2h; Add the appropriate ammoniacal liquor containing ammonia 25%～28%, dropwise drip a certain amount of ethyl orthosilicate TEOS, the volume ratio of ammoniacal liquor, TEOS and mixed solution b is 0.28～0.8:0.17～0.26:100, continues to stir 6～15h, washs and remove surfactant; Obtain Fe 3o 4/ CuO/pSiO 2magnetic coupling catalyst.
2. a kind of Fe according to claim 1 3o 4/ CuO/pSiO 2catalyst, is characterized in that: described Fe 3o 4/ CuO/pSiO 2in preparation method's step (1) of catalyst, adding the concentration of citric acid solution is 1.0～1.2mol/L; The described NH adding 3h 2o is containing ammonia 25～28%; The concentration of the PVP solution a that the described molecular weight making is 58000 is 3.44～4.31mol/L.
3. a kind of Fe according to claim 1 3o 4/ CuO/pSiO 2catalyst, is characterized in that: described Fe 3o 4/ CuO/pSiO 2in preparation method's step (1) of catalyst, the time of ultrasonic dispersion is 10～30min, and the temperature and time reacting in shaking bath is respectively 25～35 ℃ and 20～30h.
4. a kind of Fe according to claim 1 3o 4/ CuO/pSiO 2catalyst, is characterized in that: described Fe 3o 4/ CuO/pSiO 2in preparation method's step (2) of catalyst, the concentration of the ethanolic solution of preparation Schweinfurt green is 0.010～0.015mol/L.
5. a kind of Fe according to claim 1 3o 4/ CuO/pSiO 2catalyst, is characterized in that: described Fe 3o 4/ CuO/pSiO 2described in preparation method's step (2) of catalyst, the temperature of hydro-thermal reaction is 160～180 ℃, and the reaction time is 40～80min.
6. a kind of Fe according to claim 1 3o 4/ CuO/pSiO 2catalyst, is characterized in that: described Fe 3o 4/ CuO/pSiO 2described in preparation method's step (3) of catalyst, in the mixed solution b of deionized water and absolute ethyl alcohol, the volume ratio of deionized water and absolute ethyl alcohol is 1.3:1～1.5:1, the concentration of described softex kw CTAB in mixed solution b is 0.05～0.08mol/L, Fe 3o 4the mass ratio of/CuO and CTAB is 2.7:1～5.0:1, and the volume ratio that adds ammoniacal liquor, ethyl orthosilicate and mixed solution b is 0.28～0.8:0.17～0.26:100.
7. a kind of Fe according to claim 1 3o 4/ CuO/pSiO 2catalyst, is characterized in that: described Fe 3o 4/ CuO/pSiO 2the removal of surfactant described in preparation method's step (3) of catalyst adopts fast ion exchange method, and the ethanolic solution of preparation ammonium nitrate is as extractant, and its concentration is 0.18～0.25mol/L, finally washs and room temperature vacuum drying; Or the removal of the high-temperature calcination under employing nitrogen protection surfactant, temperature is controlled at 450～550 ℃, calcining 3～6h.
8. a kind of Fe according to claim 1 3o 4/ CuO/pSiO 2catalyst, is characterized in that: this catalyst is mainly used in catalytic oxidation epoxidation reaction of olefines, and by Magnetic Isolation, realizes the quick recovery of catalyst, reaches the good effect that recycles.
CN201210186971.0A 2012-06-07 2012-06-07 Fe3O4/CuO/pSiO2 catalyst and preparation method thereof Expired - Fee Related CN102688760B (en)

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