CN101016172A

CN101016172A - Preparing process for nano alpha-Fe2O3 by glycerin atmosphere pressure crystallization method

Info

Publication number: CN101016172A
Application number: CN 200610041767
Authority: CN
Inventors: 朱作远
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-02-09
Filing date: 2006-02-09
Publication date: 2007-08-15

Abstract

The invention discloses a new manufacturing technique of nanometer alpha-Fe2O3 through pressing glycerine under normal pressure, which comprises the following steps: 1. making high-purity liquid of Fe3+ salt; 2. reacting excessive ammonia and Fe3+ liquid to make Fe (OH) 3 latex; insulating the flocculating sediment; filtering Fe (OH) 3; rinsing through pure water; emulsifying with glycerine evenly; heating to dehydrate; obtaining Fe (OH) 3 gel; 3. isotroping; adding into high-temperature heat autoclave; sealing; obtaining Fe2O3 glycerine slurry; draining steam; 4. heating anhydrous Fe2O3 glycerine slurry under 0.2atm at 240-260 deg.c; recycling glycerine through condenser; recycling alpha-Fe2O3 nanometer product; 5. recycling reacting mother liquid; adding acid to neutralize; dehydrating; obtaining the by-product of ammonium salt.

Description

Nano α -Fe by glycerin atmospheric pressure crystallization method2O3Production technology

(I) technical field

The invention provides a production technology of inorganic chemical products, in particular to a nano α -Fe by glycerol normal pressure crystallization₂O₃A production technology.

(II) technical background

Production of nano α -Fe₂O₃A supercritical crystallizing process for preparing the representative alcohol from Fe by ammonia water neutralization³⁺High purity salt solution to obtain Fe (OH)₃↓, filtering, rinsing with pure water, washing with absolute ethyl alcohol, replacing Fe (OH)₃The cement contains water to obtain ethanol Fe (OH)₃Gel is put into a high-pressure kettle, dried at the temperature of more than or equal to 260 ℃ under the pressure of 8MPa, dehydrated and dehydrated to obtain the nanometer α -Fe₂O₃And (5) producing the product. The process has the advantages of large ethanol consumption, large byproduct mass ethanol containing washing water, dehydration and regeneration, large investment, trouble, high energy consumption, flammability and explosiveness, dehydration and dealcoholization under 8MPa, belongs to supercritical crystallization, and has expensive equipment and complex technology, so the process has high cost and difficult large scale.

The invention uses glycerin (glycerol) to replace ethanol, and glycerin is added to filter out water-containing Fe (OH)₃A daub of glycerin and Fe (OH) repeatedly emulsified₃Mixing with molecular grade, vacuum concentrating at low temperature to remove free water to obtain anhydrous glycerol Fe (OH)₃Homogenizing the daub, and removing the bound water at a temperature of more than or equal to 260 DEG C Boiling point of glycerin is 290 ℃ under normal pressure, and Fe is generated at the moment₂O₃Still in the glycerol molecule, when the glycerol is heated to more than or equal to 290 ℃ and is vaporized, the content of Fe is reduced₂O₃The melting point is very high, the nano α -Fe can not be agglomerated at about 290 ℃ at all, and the nano α -Fe is produced₂O₃Twomajor keys are: highly dispersed and nano Fe-proof₂O₃The crystal grains grow up and are agglomerated, the addition of the glycerol can be ensured at the same time, the boiling point of the glycerol is higher than that of the ethanol, the dielectric constant is large, the agglomeration resistance is better, the vapor condensation and recovery are simple, the energy is saved, the operation is carried out under normal pressure, the equipment can be self-made, and the large-scale production is not difficult.

Disclosure of the invention

The process of the invention is that ① produces Fe³⁺Salt high-purity liquid: FeCl₃、Fe₂(SO₄)₃、Fe(NO₃)₃And the like, wherein Fe (NO)₃)₃The salt has the best effect, and FeCO can be used₃Or iron filings as raw material is reacted with excessive nitric acid to produce ferric nitrite, which is then fine filtered to remove dregs, because the iron filings are reduced and substituted by Ni, Co, Cu and Pb, etc. and most of the alloy components of C, Si, P and S in iron can be removed simultaneously, Al and Mn can be absorbed by ion exchanger to obtain purified Fe (NO)₃)₂After the solution is treated, under the action of excessive nitric acid, blowing purified air or adding hydrogen peroxide to oxidize into Fe (NO)₃)₃Liquid with concentration controlled at about 0.6mol/L, ② Fe³⁺The salt high-purity liquid is controlled within 35 +/-2 ℃, ammonia water with the concentration of 16-20 percent and N are added under strong stirring₂Preferably, the pH value of the reaction is 9 +/-0.5 under protection, and a small amount of polymer is addedAcrylamide (20 g/m)³) Stirring for 20 min, standing for a day and night, filtering out precipitate, and purifying water to remove acid radical ions to obtain Fe (OH)₃Aqueous cement ③ glycerol in aqueous Fe (OH)₃In the cement, the anhydrous glycerin is Fe (OH)₃Homogenizing for 3-4 times (ultrasonic emulsifier, colloid mill, etc.) with homogenizer, adding into vacuum concentrator, concentrating under 0.2 atmospheric pressure to remove free water to obtain anhydrous glycerol Fe (OH)₃Gel ④ anhydrous Glycerol Fe (OH)₃Passing the gel through a homogenizer for 3 times, placing into a hot medium kettle, heating with heat-conducting oil or salt bath, or heating with electricity, medium frequency electricity, or far infrared ray, etc., heating the gel in the kettle to 260 deg.C or higher, and reacting for 1 hr under heat preservation to obtain the final product (vapor) reaction, wherein the boiling point of glycerol at normal pressure is 290 ℃, the viscosity at normal temperature is high, the viscosity at 120 ℃ and 260 ℃ is low, and Fe (OH)₃The molecules are pyrolyzed under the surrounding of glycerol molecules and are dehydrated into α -Fe₂O₃No agglomeration and no crystal growth at this temperature, releasing vaporized water, heating to 240-260 deg.C under 0.2 atmospheric pressure, vaporizing glycerol, passing glycerol vapor through a condenser, recovering liquid glycerol for reuse, vaporizing glycerol under negative pressure to prevent decomposition of local superheated glycerol, recovering liquid glycerol containing small amount of α -Fe₂O₃The particles are red, do not affect the recycling, and are cooled and recovered with α -Fe₂O₃⑤ recovering mother liquid, neutralizing ammonia with acid to neutrality, concentrating, dewatering and crystallizing to obtain ammonium salt as by-product α -Fe₂O₃The particle size is adjustable between 10 nm and 500 nm.

Claims

Glycerol process nanometer α -Fe₂O₃The new production technology comprises the following steps:

①Fe³⁺the preparation of high-purity salt solution belongs to the existing technology;

② neutralizing with ammonia water to prepare Fe (OH)₃The two or more than two of the obtained water-containing cement areIn the prior art, protection is not needed;

③ Glycerol in aqueous Fe (OH)₃Daubing with anhydrous glycerin of Fe (OH)₃Homogenizing for 3-4 times (ultrasonic emulsifier or colloid mill) with homogenizer at weight ratio of 25%, adding into vacuum concentrator, concentrating under 0.2 atmospheric pressure to remove free water to obtain anhydrous glycerol Fe (OH)₃Gelling;

④ Glycerol anhydrous Fe (OH)₃Homogenizing for 3 times, loading into pyrolysis kettle, heating to 260 deg.C or higher, and reacting for 1 hr to obtain gelThe reaction is thorough, water vapor is discharged, the temperature is raised to 240-260 ℃ under the atmospheric pressure of less than 0.2, the glycerol is vaporized to the full extent, the glycerol vapor is pumped out of a condenser and recycled to regenerate liquid glycerol for circulation, the glycerol is vaporized under negative pressure, the boiling point is reduced, the overheating decomposition of local glycerol is prevented, and α -Fe of the glycerol is removed to the full extent₂O₃The nanometer powder has controllable granularity of 10-500nm, narrow particle size distribution, different excipient and controllable crystal form, and theprocess is superior to supercritical alcohol crystallizing process.

The above four requests are protected for intellectual property rights.