CN115259215B - High-crystallinity large-specific-surface-area nano titanium dioxide and preparation method thereof - Google Patents
High-crystallinity large-specific-surface-area nano titanium dioxide and preparation method thereof Download PDFInfo
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- CN115259215B CN115259215B CN202210918968.7A CN202210918968A CN115259215B CN 115259215 B CN115259215 B CN 115259215B CN 202210918968 A CN202210918968 A CN 202210918968A CN 115259215 B CN115259215 B CN 115259215B
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- SOQBVABWOPYFQZ-UHFFFAOYSA-N oxygen(2-);titanium(4+) Chemical compound [O-2].[O-2].[Ti+4] SOQBVABWOPYFQZ-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 238000002360 preparation method Methods 0.000 title claims abstract description 22
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 87
- 238000006243 chemical reaction Methods 0.000 claims abstract description 74
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 claims abstract description 35
- 230000006911 nucleation Effects 0.000 claims abstract description 25
- 238000010899 nucleation Methods 0.000 claims abstract description 25
- 238000006460 hydrolysis reaction Methods 0.000 claims abstract description 22
- 230000007062 hydrolysis Effects 0.000 claims abstract description 20
- 239000000243 solution Substances 0.000 claims description 51
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 48
- 238000000034 method Methods 0.000 claims description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 15
- 238000002156 mixing Methods 0.000 claims description 14
- 239000000376 reactant Substances 0.000 claims description 14
- 238000003756 stirring Methods 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 5
- 238000005406 washing Methods 0.000 claims description 5
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 4
- 239000012716 precipitator Substances 0.000 claims description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 238000002347 injection Methods 0.000 claims description 3
- 239000007924 injection Substances 0.000 claims description 3
- 230000001105 regulatory effect Effects 0.000 claims description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims 1
- 239000004408 titanium dioxide Substances 0.000 abstract description 22
- 238000012546 transfer Methods 0.000 abstract description 14
- 239000013078 crystal Substances 0.000 abstract description 11
- 239000000463 material Substances 0.000 abstract description 5
- 238000011065 in-situ storage Methods 0.000 abstract description 3
- 238000012360 testing method Methods 0.000 description 16
- 229910010413 TiO 2 Inorganic materials 0.000 description 7
- 238000002441 X-ray diffraction Methods 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- 239000000047 product Substances 0.000 description 6
- 238000001354 calcination Methods 0.000 description 5
- 229910052719 titanium Inorganic materials 0.000 description 5
- 239000010936 titanium Substances 0.000 description 5
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 230000001276 controlling effect Effects 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 238000001291 vacuum drying Methods 0.000 description 4
- 235000011114 ammonium hydroxide Nutrition 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 239000000706 filtrate Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 238000009472 formulation Methods 0.000 description 2
- 230000003301 hydrolyzing effect Effects 0.000 description 2
- 238000010902 jet-milling Methods 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000003980 solgel method Methods 0.000 description 2
- -1 titanium alkoxide Chemical class 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000006399 behavior Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000003837 high-temperature calcination Methods 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- DCKVFVYPWDKYDN-UHFFFAOYSA-L oxygen(2-);titanium(4+);sulfate Chemical compound [O-2].[Ti+4].[O-]S([O-])(=O)=O DCKVFVYPWDKYDN-UHFFFAOYSA-L 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 229910000349 titanium oxysulfate Inorganic materials 0.000 description 1
- 229910000348 titanium sulfate Inorganic materials 0.000 description 1
- 238000000108 ultra-filtration Methods 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G23/00—Compounds of titanium
- C01G23/04—Oxides; Hydroxides
- C01G23/047—Titanium dioxide
- C01G23/053—Producing by wet processes, e.g. hydrolysing titanium salts
- C01G23/0536—Producing by wet processes, e.g. hydrolysing titanium salts by hydrolysing chloride-containing salts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/30—Three-dimensional structures
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Nanotechnology (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Composite Materials (AREA)
- Materials Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
The invention provides high-crystallinity large-specific-surface-area nano titanium dioxide and a preparation method thereof, belonging to the technical field of nano titanium dioxide. According to the invention, the microreactor is combined with the traditional reaction kettle, and the rapid hydrolysis nucleation of titanium tetrachloride and a precipitant is effectively controlled by virtue of the finite field reaction characteristic of the microreactor, wherein the uniform temperature and material concentration environment is ensured by utilizing the microreaction environment of high-efficiency mass transfer and high-efficiency heat transfer of the microreactor, so that uniform and rapid nucleation is realized; meanwhile, the reaction process assists an in-situ pH control charging system, the pH value in the reaction kettle is kept constant and controllable, crystal nuclei are controlled to slowly and uniformly grow, and the prepared titanium dioxide has the advantages of high crystallinity and large specific surface area. Experimental results show that the crystallinity of the titanium dioxide prepared by the preparation method provided by the invention reaches 66.8%, and the specific surface area reaches 323.6m 2 /g。
Description
Technical Field
The invention belongs to the technical field of nano titanium dioxide, and particularly relates to high-crystallinity large-specific-surface-area nano titanium dioxide and a preparation method thereof.
Background
At present, the preparation method of nano titanium dioxide mainly adopts a gas phase method and a liquid phase method. The titanium dioxide product prepared by gas phase synthesis has small particle size, large surface activity, good dispersibility and small agglomeration degree. However, the high reaction temperature has high requirements on corrosion resistance of equipment and accurate control of technological parameters, so that the product cost is high, and further application of the technology is limited. The liquid phase method mainly comprises a precipitation method, a sol-gel method, a hydrolysis method and the like, wherein the precipitation method uses titanyl sulfate or titanium sulfate as a titanium source, and sodium hydroxide or sodium bicarbonate as an alkali source to carry out precipitation reaction, so that the particle size of the obtained particles is larger; the sol-gel method generally takes titanium alkoxide as a reactant, alcohol as a solvent and hydrolyzes into gel for preparation, but a large number of crystal nuclei are difficult to form in the initial stage of the reaction, and the overall reaction time is long; the hydrolysis method generally takes titanium tetrachloride as a raw material, and promotes titanium tetrachloride hydrolysis by adding ammonia water or a thermal initiation method, but the concentration field and the temperature field in the traditional kettle type equipment are wide in distribution, so that the requirements of rapid heat transfer and mass transfer of hydrolysis reaction are difficult to meet, uniform reaction conditions cannot be ensured, the nucleation and growth behaviors of particles exist in the reaction process at the same time, the problems of particle enlargement and particle size distribution broadening are easily caused, the crystallinity of nano titanium dioxide is low, and the specific surface area is small.
Therefore, how to prepare nano titanium dioxide with high crystallinity and large specific surface area is a difficult problem to be solved in the field.
Disclosure of Invention
The invention aims to provide nano titanium dioxide with high crystallinity and large specific surface area and a preparation method thereof. The nano titanium dioxide prepared by the preparation method provided by the invention has high crystallinity and large specific surface area.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of nano titanium dioxide with high crystallinity and large specific surface area, which comprises the following steps:
(1) Mixing titanium tetrachloride solution and a precipitator in a micro-reactor, and carrying out hydrolysis nucleation to obtain a reactant; the precipitant is injected into the microreactor by adopting a pH value feedback feeding system;
(2) Mixing the reactant obtained in the step (1) with water in a reaction kettle, and carrying out a growth reaction to obtain nano titanium dioxide with high crystallinity and large specific surface area; the growth reaction adopts a pH value feedback feeding system to adjust the pH value.
Preferably, the concentration of the titanium tetrachloride solution in the step (1) is 10 to 40% by weight.
Preferably, the titanium tetrachloride solution in the step (1) is injected into the microreactor at a flow rate of 2-20 mL/min by using an injection pump.
Preferably, the precipitant in the step (1) includes one of sodium hydroxide solution, potassium hydroxide solution and ammonia water.
Preferably, the concentration of the precipitant is 5 to 25wt%.
Preferably, the precipitant in the step (1) is injected into the microreactor at a flow rate of 2-20 mL/min by using a pH value feedback feeding system.
Preferably, the hydrolysis nucleation temperature in the step (1) is 30 ℃.
Preferably, the growth reaction in step (2) is carried out under stirring.
Preferably, the temperature of the growth reaction in the step (2) is 60-90 ℃, and the time of the growth reaction is 1-2 h.
The invention also provides the nano titanium dioxide with high crystallinity and large specific surface area prepared by the preparation method.
The invention provides a preparation method of nano titanium dioxide with high crystallinity and large specific surface area, which comprises the following steps: mixing titanium tetrachloride solution and a precipitator in a micro-reactor, and carrying out hydrolysis nucleation to obtain a reactant; the precipitant is injected into the microreactor by adopting a pH value feedback feeding system; mixing the reactant with water in a reaction kettle, and carrying out a growth reaction to obtain nano titanium dioxide with high crystallinity and large specific surface area; the growth reaction adopts a pH value feedback feeding system to adjust the pH value. According to the invention, the microreactor is combined with the traditional reaction kettle, and the rapid hydrolysis nucleation of titanium tetrachloride and a precipitant is effectively controlled by virtue of the finite field reaction characteristic of the microreactor, wherein the uniform temperature and material concentration environment is ensured by utilizing the microreaction environment of high-efficiency mass transfer and high-efficiency heat transfer of the microreactor, so that uniform and rapid nucleation is realized; meanwhile, the reaction process assists an in-situ pH control charging system, the pH value in the reaction kettle is kept constant and controllable, crystal nuclei are controlled to slowly and uniformly grow, and the prepared titanium dioxide has the advantages of high crystallinity and large specific surface area. Experimental results show that the crystallinity of the titanium dioxide prepared by the preparation method provided by the invention reaches 66.8%, and the specific surface area reaches 323.6m 2 /g。
Drawings
FIG. 1 is a schematic diagram of an apparatus for preparing nano titania in example 1;
in the figure, 1 is a syringe pump, 2 is a pH value feedback feeding system, 3 is a microreactor, and 4 is a reaction kettle;
FIG. 2 is an XRD pattern of nano titania prepared in example 1;
FIG. 3 is an XRD pattern of nano titania prepared in example 2;
FIG. 4 is an XRD pattern of nano titania prepared in example 3;
FIG. 5 is an XRD pattern of nano titania prepared in example 4;
FIG. 6 is an XRD pattern of nano titania prepared in example 5;
fig. 7 is an XRD pattern of the titanium oxide prepared in comparative example 1.
Detailed Description
The invention provides a preparation method of nano titanium dioxide with high crystallinity and large specific surface area, which comprises the following steps:
(1) Mixing titanium tetrachloride solution and a precipitator in a micro-reactor, and carrying out hydrolysis nucleation to obtain a reactant; the precipitant is injected into the microreactor by adopting a pH value feedback feeding system;
(2) Mixing the reactant obtained in the step (1) with water in a reaction kettle, and carrying out a growth reaction to obtain nano titanium dioxide with high crystallinity and large specific surface area; the growth reaction adopts a pH value feedback feeding system to adjust the pH value.
The invention mixes titanium tetrachloride solution and precipitant in micro reactor to hydrolyze and nucleate to obtain reactant. The invention effectively controls the quick hydrolysis nucleation of titanium tetrachloride and precipitant by means of the finite field reaction characteristic of the microreactor, wherein the microreaction environment of high-efficiency mass transfer and high-efficiency heat transfer of the microreactor is utilized, which is helpful for ensuring uniform temperature and material concentration environment and realizing uniform and quick nucleation.
In the present invention, the concentration of the titanium tetrachloride solution is preferably 10 to 40wt%, more preferably 20 to 25wt%; the titanium tetrachloride solution is preferably an aqueous solution of titanium tetrachloride. The source of the titanium tetrachloride solution is not particularly limited in the present invention, and may be formulated by commercially available products known to those skilled in the art or by a known formulation method. In the invention, the titanium tetrachloride solution is used as an inorganic titanium source, the raw material sources are wide, the cost is low and the raw material is easy to obtain, and the price is far lower than that of organic titanium sources such as titanium alkoxide, titanate and the like, and the method has the advantage of low production cost.
In the present invention, the titanium tetrachloride solution is preferably injected into the microreactor at a flow rate of 2 to 20mL/min using a syringe pump, and more preferably injected into the microreactor at a flow rate of 10 to 15mL/min using a syringe pump. The type of the syringe pump is not particularly limited, and the syringe pump can be manufactured by instruments and devices known to those skilled in the art. The invention can further ensure the uniformity of the hydrolysis nucleation concentration field in the microreactor by controlling the flow rate of the titanium tetrachloride solution, thereby improving the crystallinity and specific surface area of the titanium dioxide.
In the present invention, the precipitant preferably includes one of sodium hydroxide solution, potassium hydroxide solution and ammonia water; the concentration of the precipitant is preferably 5 to 25wt%, more preferably 19.5 to 22.5wt%, and even more preferably 22wt%. The source of the precipitant is not particularly limited in the present invention, and may be formulated by commercially available products known to those skilled in the art or by a known formulation method.
In the invention, the precipitant is injected into the microreactor by using a pH value feedback feeding system, preferably the precipitant is injected into the microreactor by using the pH value feedback feeding system at a flow rate of 2-20 mL/min, and more preferably the precipitant is injected into the microreactor by using the pH value feedback feeding system at a flow rate of 10-15 mL/min. The type of the pH value feedback feeding system is not particularly limited, and instruments and equipment well known to those skilled in the art can be adopted. The invention adopts the pH value feedback feeding system to ensure that the reaction environment is maintained stable in the rapid hydrolysis reaction process of titanium tetrachloride and the precipitant, thereby improving the crystallinity and specific surface area of titanium dioxide.
In the present invention, the microreactor is preferably a continuous flow microreactor. The type of the microreactor is not particularly limited, and the microreactor can be any type of microreactor by means of instruments and equipment known to those skilled in the art. The invention adopts the microreactor to utilize the threshold-limiting reaction characteristic and has high-efficiency mass and heat transfer microreaction environment, and the microreactor is used as a continuous flow threshold microreaction device, compared with a conventional tubular reactor, the specific surface area volume ratio is very large (can reach 10000-50000 m) 2 /m 3 ) Therefore, the microreactor has extremely high mixing efficiency (radial complete mixing is realized in the millisecond range), extremely strong heat exchange capacity (the heat transfer coefficient can reach 25000W/m 2 K) and extremely narrow residence time distribution (almost no back-mixing, near plug flow), and is relatively simple in construction and excellent in safetyThe method comprises the steps of carrying out a first treatment on the surface of the Based on the efficient heat transfer and mass transfer of the microreactor and the characteristic of the finite field reaction, the preparation requirement of the rapid hydrothermal reaction can be met, the uniform nucleation is realized, on the basis, the constant condition of the growth process is ensured, the uniform growth is controlled, the control requirement of nucleation and growth is reached, and the crystallinity and the specific surface area of the titanium dioxide are improved.
In the present invention, the flow rate of the titanium tetrachloride solution in the microreactor is preferably the same as the flow rate of the titanium tetrachloride solution injected into the microreactor, and will not be described herein; the flow rate of the precipitant in the microreactor is preferably the same as the flow rate of the precipitant injected into the microreactor, and will not be described in detail herein.
The mixing operation of the titanium tetrachloride solution and the precipitant in the microreactor is not particularly limited in the present invention, and may be carried out by mixing operations well known to those skilled in the art.
In the present invention, the temperature of the hydrolytic nucleation is preferably 30 ℃; the temperature of the hydrolytic nucleation is preferably controlled by a low temperature water circulation system. The present invention is not particularly limited to the operation of controlling the low temperature water circulation system, and may employ a temperature control system well known to those skilled in the art. The time for the hydrolysis nucleation is not particularly limited in the present invention, so long as the titanium tetrachloride solution and the precipitant are ensured to flow through the microreactor after being mixed.
After the reactant is obtained, the reactant is mixed with water in a reaction kettle to perform a growth reaction, so that the nano titanium dioxide with high crystallinity and large specific surface area is obtained.
In the present invention, the water is preferably deionized water; the volume ratio of the titanium tetrachloride solution to the water is preferably (1-4): 1, more preferably (2 to 3): 1. the source of the water is not particularly limited in the present invention, and commercially available products known to those skilled in the art may be used. In the invention, the water is used as the base solution, so that the stirring operation is convenient.
The type of the reaction kettle is not particularly limited, and instruments and equipment well known to those skilled in the art can be adopted.
In the present invention, the growth reaction uses a pH feedback feed system to adjust pH. The invention adopts the pH value feedback feeding system to adjust the pH value, can keep the pH value in the reaction kettle constant and controllable, controls the crystal nucleus to slowly and uniformly grow, and ensures that the prepared titanium dioxide has the advantages of large specific surface area, high crystallinity, controllable crystal form and the like.
In the present invention, the pH feedback feed system is preferably the same as that employed in the aforementioned hydrolysis nucleation.
In the present invention, the material used for adjusting the pH value in the growth reaction is preferably the same as the precipitant used in the aforementioned hydrolysis nucleation, and will not be described in detail herein.
In the present invention, when it is desired to prepare rutile titanium dioxide, the pH of the growth reaction is preferably from 0 to 0.10, more preferably from 0 to 0.05; when it is desired to prepare anatase titanium dioxide, the pH of the growth reaction is preferably from 0.50 to 5.00, more preferably from 0.60 to 3.00; when it is desired to prepare mixed crystal forms (rutile titanium dioxide and anatase titanium dioxide), the pH of the growth reaction is preferably 0.10 to 0.50, more preferably 0.10 to 0.30.
In the present invention, the growth reaction is preferably performed under stirring; the stirring speed is preferably 200-800 r/min, more preferably 300-600 r/min; the temperature of the growth reaction is preferably 60 to 90 ℃, more preferably 70 to 80 ℃; the time of the growth reaction is preferably 1 to 2 hours. The invention can control the growth of titanium dioxide by controlling the temperature and time of the growth reaction, thereby further improving the crystallinity and specific surface area thereof.
After the growth reaction is completed, the product obtained by the growth reaction is preferably filtered, washed, dried and crushed in sequence to obtain the nano titanium dioxide with high crystallinity and large specific surface area.
The operation of the filtration and washing is not particularly limited in the present invention, as long as the conductivity of the filtrate is made to be lower than 25. Mu.S/cm.
In the present invention, the drying is preferably vacuum drying; the drying temperature is preferably 40 to 60 ℃. The drying time is not particularly limited, and the drying is carried out until the weight is constant.
In the present invention, the pulverization is preferably jet pulverization. The operation of the jet milling is not particularly limited, and may be performed by those known to those skilled in the art.
According to the invention, the microreactor is combined with the traditional reaction kettle, and the rapid hydrolysis nucleation of titanium tetrachloride and a precipitant is effectively controlled by virtue of the finite field reaction characteristic of the microreactor, wherein the uniform temperature and material concentration environment is ensured by utilizing the microreaction environment of high-efficiency mass transfer and high-efficiency heat transfer of the microreactor, so that uniform and rapid nucleation is realized; meanwhile, the reaction process assists an in-situ pH control charging system, the pH value in the reaction kettle is kept constant and controllable, crystal nuclei are controlled to slowly and uniformly grow, and the prepared titanium dioxide has the advantages of high crystallinity and large specific surface area.
The preparation method disclosed by the invention has the advantages that the process route is simple, stable and uniform nano titanium dioxide particles can be obtained in a short time, other salt substances are not introduced in the preparation process, new salt-containing wastewater is not generated, the preparation method is environment-friendly, a high-temperature calcination process is not needed, the energy consumption is lower, and the problems in the traditional process can be remarkably improved under the excellent characteristics of low cost, high efficiency and controllability.
The invention also provides the nano titanium dioxide with high crystallinity and large specific surface area prepared by the preparation method.
The nano titanium dioxide provided by the invention has the advantages of high crystallinity, large surface area and controllable crystal form.
The technical solutions of the present invention will be clearly and completely described in the following in connection with the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
The preparation process of nanometer titania with high crystallinity and great specific surface area includes the following steps:
(1) 200mL of 25wt% titanium tetrachloride solution is injected into a continuous flow microreactor with the inner diameter of 0.21mm by adopting a syringe pump at the flow rate of 20mL/min, 200mL of 15wt% sodium hydroxide solution is injected into the continuous flow microreactor with the inner diameter of 0.21mm by adopting a pH value feedback feeding system at the flow rate of 20mL/min, and is mixed with the titanium tetrachloride solution, so as to carry out hydrolysis nucleation, thus obtaining a reactant; wherein, the temperature of hydrolysis nucleation is controlled to be 30 ℃ by adopting a low-temperature water circulation system;
(2) Injecting the reactant obtained in the step (1) into a 1L reaction kettle, mixing with 100mL of deionized water, controlling the stirring speed in the reaction kettle to be 550r/min, performing a growth reaction, washing the filtrate by adopting a tangential flow ultrafiltration membrane to ensure that the conductivity of the filtrate is lower than 25 mu S/cm, and performing vacuum drying and jet milling to obtain the nano titanium dioxide with high crystallinity and large specific surface area; wherein, the pH value of the reaction solution in the kettle is monitored in real time by a pH value feedback feeding system in the growth reaction, the flow rate of the sodium hydroxide solution (the variation range of <5 mL/min) is regulated, and the pH value in the reaction process is accurately controlled to be 0.00; the temperature of the growth reaction is 80 ℃ and the time is 1h; the temperature of the vacuum drying was 60 ℃.
The schematic structure of the apparatus for preparing nano titanium dioxide in example 1 is shown in fig. 1, wherein 1 is a syringe pump, 2 is a pH feedback feeding system, 3 is a microreactor, and 4 is a reaction kettle.
XRD test was performed on the nano titania prepared in example 1, and the test results are shown in fig. 2.
As can be seen from FIG. 2, the diffraction peak of nano titanium dioxide corresponds to TiO 2 (JCPLDS#21-1276) is a typical rutile type titanium dioxide with a crystallinity of 55.3% and was subjected to a specific surface area test, resulting in 294.9m 2 /g。
Example 2
The difference from example 1 is that: the concentration of the sodium hydroxide solution in the step (1) is 19.5 weight percent, and the flow rates of the titanium tetrachloride solution and the sodium hydroxide solution are 10mL/min; in the step (2), the pH value of the reaction solution in the kettle is monitored in real time by adopting a pH value feedback feeding system, and the pH value in the reaction process is accurately controlled to be 0.12.
XRD test is carried out on the nano titanium dioxide prepared in the embodiment 2, and the test result is shown in figure 3, wherein the black line is anatase titanium dioxide; the red line is rutile type titanium dioxide.
As can be seen from FIG. 3, the diffraction peak of nano titanium dioxide corresponds to TiO 2 (PDF 21-1276) and TiO 2 (PDF 21-1272) of mixed crystal forms of anatase and rutile, the crystallinity of the main crystal face of anatase was 40.6%, and the specific surface area thereof was tested and found to be 289.8m 2 /g。
Example 3
The difference from example 1 is that: the concentration of the sodium hydroxide solution in the step (1) is 22 weight percent, and the flow rates of the titanium tetrachloride solution and the sodium hydroxide solution are 10mL/min; in the step (2), the pH value of the reaction solution in the kettle is monitored in real time by adopting a pH value feedback feeding system, and the pH value in the reaction process is accurately controlled to be 0.70.
XRD testing was performed on the nano titania prepared in example 3, and the test results are shown in fig. 4.
As can be seen from FIG. 4, the diffraction peak of nano titanium dioxide corresponds to TiO 2 (PDF 21-1272) which is of anatase type and has a crystallinity of 66.8%, was subjected to a specific surface area test and found to be 323.6m 2 /g。
Example 4
The difference from example 1 is that: the concentration of the sodium hydroxide solution in the step (1) is 22.5 weight percent, and the flow rates of the titanium tetrachloride solution and the sodium hydroxide solution are 10mL/min; in the step (2), the pH value of the reaction solution in the kettle is monitored in real time by adopting a pH value feedback feeding system, and the pH value in the reaction process is accurately controlled to be 2.60.
XRD test was performed on the nano titania prepared in example 4, and the test results are shown in fig. 5.
As can be seen from FIG. 5, the diffraction peak of nano titanium dioxide corresponds to TiO 2 (PDF 21-1272) which is of anatase type and has a crystallinity of 21.4%, and which was subjected to a specific surface area test, as a result, 271.6m 2 /g。
Example 5
The difference from example 1 is that: the concentration of the sodium hydroxide solution in the step (1) is 23wt%, and the flow rates of the titanium tetrachloride solution and the sodium hydroxide solution are 10mL/min; in the step (2), the pH value of the reaction solution in the kettle is monitored in real time by adopting a pH value feedback feeding system, and the pH value in the reaction process is accurately controlled to be 3.0.
XRD test was performed on the nano titania prepared in example 5, and the test results are shown in fig. 6.
As can be seen from FIG. 6, the diffraction peak of nano titanium dioxide corresponds to TiO 2 (PDF 21-1272) which is of anatase type and has a crystallinity of 41.6% and which was subjected to a specific surface area test to give a result of 290.3m 2 /g。
Comparative example 1
The steps for preparing anatase titanium dioxide are as follows:
200mL of 25wt% titanium tetrachloride solution is taken as a base solution and placed in a three-necked flask, and 200mL of 15wt% sodium hydroxide aqueous solution is taken;
injecting the sodium hydroxide solution into a three-neck flask at a flow rate of 10.0mL/min through an injection pump to perform neutralization precipitation reaction, stirring to pH=6.50 at a low-temperature circulating water of 30 ℃, filtering, washing until the conductivity of a washing solution is less than 25 mu S/cm, vacuum drying to obtain a precipitate (amorphous titanium dioxide after XRD analysis), and calcining the precipitate at a calcining temperature of 410 ℃ at a heating rate of 5 ℃/min for 2 hours to obtain anatase titanium dioxide with complete crystal forms.
XRD test was conducted on the titania produced in comparative example 1, and the test results are shown in FIG. 7.
As can be seen from FIG. 7, the diffraction peak of titanium dioxide corresponds to TiO 2 (PDF 21-1272) of anatase type having a crystallinity of 50.4% and a specific surface area of 89.2m 2 /g。
As can be seen from comparing comparative example 1 with examples 1 to 5, when titanium dioxide is prepared by the conventional hydrolysis method, the titanium dioxide with high crystallinity is obtained by calcining treatment, but the titanium dioxide with high crystallinity can be obtained without calcining treatment in the example of the invention, and the specific surface area of the titanium dioxide is further improved, which means that amorphous titanium dioxide is obtained when titanium dioxide is prepared by the conventional method without calcining, and the specific surface area is low, thereby proving that the preparation method of the invention can improve the crystallinity and the specific surface area of the titanium dioxide.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (5)
1. The preparation process of nanometer titania with high crystallinity and great specific surface area includes the following steps:
(1) Mixing titanium tetrachloride solution and a precipitator in a micro-reactor, and carrying out hydrolysis nucleation to obtain a reactant; the precipitant is injected into the microreactor by adopting a pH value feedback feeding system;
(2) Mixing the reactant obtained in the step (1) with water in a reaction kettle, carrying out a growth reaction, and then sequentially filtering, washing, drying and crushing to obtain nano titanium dioxide with high crystallinity and large specific surface area; the pH value of the growth reaction is regulated by adopting a pH value feedback feeding system, and the pH value in the reaction kettle is kept constant and controllable; the pH value of the growth reaction is 0-5;
the hydrolysis nucleation temperature in the step (1) is 30 ℃;
the titanium tetrachloride solution in the step (1) is injected into the microreactor by adopting an injection pump at a flow rate of 2-20 mL/min;
the precipitant in the step (1) is injected into the microreactor at a flow rate of 2-20 mL/min by adopting a pH value feedback feeding system;
the temperature of the growth reaction in the step (2) is 60-90 ℃, and the time of the growth reaction is 1-2 h.
2. The method according to claim 1, wherein the concentration of the titanium tetrachloride solution in the step (1) is 10 to 40wt%.
3. The method according to claim 1, wherein the precipitant in the step (1) comprises one of sodium hydroxide solution, potassium hydroxide solution and aqueous ammonia.
4. The method according to claim 3, wherein the concentration of the precipitant is 5 to 25wt%.
5. The method according to claim 1, wherein the growth reaction in step (2) is performed under stirring.
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| CN1386708A (en) * | 2002-03-26 | 2002-12-25 | 北京化工大学 | Nano rutile-type titanium dioxide and its preparing process |
| CN1463790A (en) * | 2002-06-13 | 2003-12-31 | 深圳市格林美环境材料有限公司 | Method for preparing nano level titanium dioxide optical catalytic environment purification material and apparatus therefor |
| DE10310028A1 (en) * | 2003-03-06 | 2004-09-16 | Penth, Bernd, Dr. | Regulating morphology in precipitation of micro- and nano-particles, e.g. for production of drug or inorganic pigment particles, involves using colliding jets of liquid in gas space at constant pH |
| RU2709093C1 (en) * | 2018-11-28 | 2019-12-13 | Федеральное государственное автономное образовательное учреждение высшего образования "Уральский федеральный университет имени первого Президента России Б.Н. Ельцина" | Titanium oxide synthesis method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1386708A (en) * | 2002-03-26 | 2002-12-25 | 北京化工大学 | Nano rutile-type titanium dioxide and its preparing process |
| CN1463790A (en) * | 2002-06-13 | 2003-12-31 | 深圳市格林美环境材料有限公司 | Method for preparing nano level titanium dioxide optical catalytic environment purification material and apparatus therefor |
| DE10310028A1 (en) * | 2003-03-06 | 2004-09-16 | Penth, Bernd, Dr. | Regulating morphology in precipitation of micro- and nano-particles, e.g. for production of drug or inorganic pigment particles, involves using colliding jets of liquid in gas space at constant pH |
| RU2709093C1 (en) * | 2018-11-28 | 2019-12-13 | Федеральное государственное автономное образовательное учреждение высшего образования "Уральский федеральный университет имени первого Президента России Б.Н. Ельцина" | Titanium oxide synthesis method |
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