Rare Earth Fluoride
Rare earth fluoride includes lanthanum fluoride, cerium fluoride, praseodymium fluoride, neodymium fluoride, gadolinium fluoride, yttrium fluoride, dysprosium fluoride, etc. It is a white powder with a purity of 99.55% to 99.99%, containing Fe2O3, etc., and the content of non rare earth impurities is less than 0.01%.
Product List
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| CAS NO. | Product Name | Inquiry |
| 68188-85-2 | Rare Earth Fluoride | Inquiry |
| 10060-10-3 | Cerium(IV) fluoride | Inquiry |
| 231-841-3 | Cerium(III)fluoridetrihydrate,96%min | Inquiry |
| 33317-01-4 | Cerium(III) fluoride, hydrate 98% | Inquiry |
| 37317-01-4 | Cerium(+3) cation trifluoride | Inquiry |
| 60627-09-0 | Cerium(IV) fluoride hydrate | Inquiry |
| 7758-88-5 | Cerium(III) fluoride | Inquiry |
| 13709-46-1 | Praseodymium trifluoride | Inquiry |
| 13709-42-7 | Neodymium(III) fluoride | Inquiry |
| 13940-76-6 | Neodymium fluoride(NdF2) (7CI,8CI,9CI) | Inquiry |
| 14932-78-6 | Neodymium fluoride hemihydrate | Inquiry |
| 13765-24-7 | Samarium Fluoride | Inquiry |
| 13765-25-8 | Europium(III) fluoride | Inquiry |
| 13765-26-9 | Gadolinium(III) fluoride | Inquiry |
| 13708-63-9 | Terbium(III) fluoride | Inquiry |
| 21031-92-5 | Terbium fluoride | Inquiry |
| 13569-80-7 | Dysprosium(III) fluoride | Inquiry |
| 13760-78-6 | Holmium(III) fluoride | Inquiry |
| 13760-79-7 | Thulium(III) fluoride | Inquiry |
| 13760-80-0 | Ytterbium(III) fluoride | Inquiry |
| 13760-81-1 | Lutetium(III) fluoride | Inquiry |
| 13760-81-8 | Lutetium fluoride | Inquiry |
The common synthesis methods of rare earth fluoride include hydrofluoric acid precipitation-vacuum dehydration method, hydrofluoride fluorination method, and ammonium hydrogen fluoride fluorination method.
Production Technology
Weigh rare earth oxides and NH4F in the required molar ratio, grind and mix them evenly, place them in a crucible, use a suitable microwave absorber, and control the appropriate reaction power and time in a microwave oven to obtain the required series of samples such as light rare earth fluorides, rare earth fluoroxides, and rare earth fluoride complex salts.
Production Example 1 - Precipitation Method
Fluorocarbons (HFCs, HCFCs) are the best compounds to replace chlorofluorocarbons (commonly known as Freon). The main methods for synthesizing HFCs include hydrogen dechlorination, liquid phase fluorination, and gas phase fluorination. The gas phase fluorination method has become the main method of industrial production due to its low pollution, easy control, and continuous production.
Gas-phase fluorination is a heterogeneous reaction, and the development of solid catalysts is the key to the gas-phase method. The main active component of the catalyst is fluoride or oxyfluoride, and the main carriers are activated carbon, Al2O3, and AlF3. These carriers can increase the effective specific surface area of the catalyst, provide a suitable pore structure, and increase the mechanical strength of the catalyst. Research on gas-phase synthesis of HFCs using magnesium carriers (MgF2 or magnesium oxide) shows that it has better performance than aluminum-based carriers. MgF2 has strong loading performance. Therefore, magnesium catalysts are a new research direction for gas-phase synthesis of HFCs.
The gas phase fluorination reaction is a fluorine and chlorine exchange reaction. Alkaline earth metal elements (such as Mg), rare earth metal elements and other Group VIII, Group VIIB, Group IIIB and Group IB elements have fluorine and chlorine exchange activity. Elements such as In, Co, Cu, Ag, Hg, Zn, and Pd can also increase catalyst activity and extend service life.
According to the preparation method, the catalyst can be divided into composite type and supported type. The composite type is prepared by co-precipitating soluble salts of Cr, Ni, Zn, etc., while the loaded type is prepared by impregnating the carrier and active components.
In order to prepare a supported MgF2-based catalyst, the carrier MgF2 or magnesium oxide should be prepared first.
The increase in temperature has little effect on the specific surface area and porosity of the fluorinated Cr-Mg catalyst; at 400 °C to 500 °C, the catalyst with a polydisperse pore structure and high specific surface area has the highest activity. In the dehydrochlorination reaction, if the roasting temperature is too high, the small pores will disappear and the activity of magnesium fluoride will be reduced. The suitable drying temperature should be lower than 100 °C. The preparation methods of supported catalysts that use MgF2 or magnesium oxide as a carrier and load active components include the main impregnation method, precipitation method, and blending method. Among them, the precipitation method is the most suitable process, and the preparation method is as follows.
Add a Cr-containing soluble salt solution to MgF2 to form a suspension, add a precipitant (generally NH3·H2O) under stirring to form a Cr(OH)3 precipitate, and obtain a catalyst precursor after filtration, drying, and shaping.
Industrially produced MgF2 has a small specific surface area and does not have catalytic properties. When preparing active MgF2, the precipitation temperature, reaction time, precipitation pH value, and drying temperature should be controlled to produce MgF2 with a specific surface area of 40 to 80 m2/g.
The drying temperature affects the main physical and chemical properties of the carrier. After activation treatment, a series of supported catalysts are prepared, including Cr/MgO2 and Cr/MgF2. MgF2 is prepared from magnesium oxide and excess hydrofluoric acid, with a specific surface area of 64 m2/g.
The components of the precipitation method are evenly distributed and have stable performance. The fluorination temperature using the dry process is controlled at 600 °C ~ 650 °C. The actual amount of hydrogen fluoride gas is 100% of the theoretical calculation. When the gas flow is 3 ~ 4 kg/h, the fluorination rate reaches 99%.
In order to reduce the particle size of rare earth fluoride, citric acid can be used as a chelating agent to slow down the release rate of F-, and nanoparticles of LaF3 : Eu3+ and GdF3 : Eu3+ with an average particle size of 17 nm are prepared. Using citric acid as a sustained-release agent in a mixed solvent of ethanol and water, silica nanoparticles coated with lanthanum fluoride can be obtained, with a shell thickness of 10 nm ~ 20 nm.
Production Example 2 - Co-precipitation
Water-soluble chitosan-coated LaF3 : Eu3+ nanoparticles can be prepared by co-precipitation in a solution containing chitosan, with an average particle size of 25 nm. The preparation process is to add an aqueous solution of ammonium fluoride to a chitosan solution of La(NO3)3 and Eu(NO3)3, heat it to 75 °C, react for 2 hours, and centrifuge to obtain chitosan-coated nanoparticles. In order to improve the crystallinity, the sample can be heat treated at a heating temperature not exceeding 450 °C. In order to reduce agglomeration, slow-release agents or ligands can be added to reduce the concentration of reactants in the system and reduce the reaction rate. Slow down the nucleation rate by lowering the temperature; adjust the pH value to control the nucleation rate; and add some crystal nuclei produced by macromolecule coating to prevent re-agglomeration.
Production Example 3 - Grinding Method
In Japanese Patent Application Publication No. 2001-365039, mixed rare earth oxides are added to mixed rare earth fluorides to prepare cerium abrasives. Japanese patent applications 2002-97458 and 2002-97457 disclose the use of X-ray diffraction grinding methods.
The preparation of rare earth metal fluoride is based on soluble rare earth salt solution, rare earth oxide, rare earth oxalate, rare earth ammonium sulfate double salt, acid type rare earth carbonate slurry as raw material liquid. Oxalic acid and hydrofluoric acid were added to the raw material solution under the condition of room temperature to boiling and stirring, and then hydrofluoric acid was added for solid-liquid separation. This method has the advantages of strong adaptability, less working procedure, short production cycle, less equipment, low consumption cost of energy and various raw materials, fast precipitation and filtration rate, stable product quality, high qualified rate, recovery rate of more than 98%, and direct discharge of fluorine-containing wastewater. easy for environmental protection and industrialization.
The best fluorine content of the mixed rare earth fluoride in this process is 20% to 30%. Mixed rare earth fluorides are derived from rare earth concentrates, such as alkali metals, alkaline earth metals and radioactive substances, and are used as raw materials after further chemical separation and removal of medium and heavy rare earths and light rare earth neodymium mixed rare earth compounds.
The mixed rare earth fluoride produced by the mixed rare earth compound slurry is precipitated and filtered, and the mixed rare earth fluoride can be obtained when the drying-precipitation temperature is 400 °C or lower than 400 °C. Examples of fluorine compounds include hydrofluoric acid, sodium fluorosilicate, and acidic ammonium fluoride.
When the drying temperature exceeds 400 °C, the fluorination reaction of rare earth oxides in the grinding process will become inconsistent, in addition, the mixed rare earth fluoride particles will produce scratches.
Mixed rare earths are mainly cerium, lanthanum, praseodymium, and neodymium.
When mixed rare earth oxides and mixed rare earth fluoride are mixed together, it is more preferable to be 75 : 25 in terms of mass ratio.
Dispersants can be added when grinding mixed rare earth oxides and mixed rare earth fluorides, especially solid phase grinding. When no dispersant is added, aggregation may occur. Examples of dispersant acids include pyrophosphoric acid, examples of alkali metal inorganic salts include phosphates (such as sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate), examples of alkali metal organic salts such as sodium polyacrylate, and others formalin.
In this process, it is more preferred that the high-temperature firing temperature is 750 °C to 1100 °C, and grinding is performed after drying. At this time, the oxygen concentration is preferably 10% to 20%. The optimal firing temperature will vary because the presence of oxygen is essential for the formation of rare earth oxyfluorides. When the oxygen concentration is less than 10%, the rare earth oxyfluorination effect is unsatisfactory. When the oxygen concentration exceeds 20%, it is unprofitable because high oxygen concentration is not conducive to the reaction of producing rare earth oxygen fluorine.
238 g of mixed rare earth fluoride and 762 g of mixed rare earth oxide were mixed and then 0.1 g of sodium phosphate was added. Then add 600 g of deionized water to the resulting mixture, dry the slurry, introduce air with an oxygen concentration of 20% at 900 °C, cool after 2 hours, and then grind to obtain this product.
Production Example 4 - Microwave Method
Weigh the rare earth oxide and NH4F according to their respective required measurement ratios, grind and mix them evenly, then place them in a crucible, use a microwave oven under the action of a suitable microwave absorber, and control the appropriate reaction power and time, that is, the required light rare earth fluoride, rare earth oxyfluoride, rare earth fluoride double salt and other products are obtained.
Direct microwave reduction fluorination synthesis is to weigh CeO2 and NH4F according to the reaction ratio (1:2), grind them, mix them evenly, and place them in a corundum crucible. Under the action of a microwave absorber, the reaction power (320 W) and time are controlled (30 min), the required sample is obtained. The low valence cerium can also be converted into Ce(OH)CO3 intermediate and then the target product can be synthesized by microwave method.
Weigh a certain amount of cerium trichloride to prepare a 0.5 mol/L aqueous solution, and add 0.16 g/L NH4HCO3 solution with stirring until the precipitation is complete and the solution becomes neutral. This solution is placed in a microwave oven and heated below 70 °C for 10 minutes. When cooled to room temperature, it is suction filtered and dried by microwave to obtain Ce(OH)CO3, which is then mixed with NH4F according to the reaction ratio of 1 : 3 and reacted under the action of microwave field to prepare the desired sample.
Production Example 5 - Modification
Rare earth inorganic compounds such as CeF3 have excellent high temperature and solid lubrication properties, but are difficult to dissolve in mineral oil and cannot be directly used as lubricating oil additives. Nanoparticles can be prepared first and then lipophilic surface modification can be carried out, so that the relevant rare earth inorganic compounds have good dispersion in mineral oil. As a result, various types of rare earth inorganic compounds including rare earth fluorides exhibit excellent extreme pressure-antiwear and friction-reducing properties.
Nano-LaF3 modified with nitrogen-containing organic compounds was prepared by microemulsion method. It has good extreme pressure, anti-wear, and friction-reducing properties in liquid paraffin, and its anti-wear and friction-reducing properties are significantly better than ZDDP.
Nano-LaF3 and CeF3 modified by pyridine alkyl phosphate and dialkyl dithiophosphate were prepared by alcohol-water coprecipitation method. The tribological properties of nano-rare earth fluoride modified by these organic compounds are also better than that of ZDDP.
Many rare earth compounds, including phosphorus-containing and phosphorus-free rare earth organic compounds and nano-rare earth inorganic compounds, can effectively improve the extreme pressure-antiwear properties of lubricating oils, and are expected to develop into a new type of low-phosphorus, phosphorus-free high-efficiency extreme pressure antiwear agents for lubricating oil.
