Cerium Oxalate Hydrate, Cerium Oxalate, Cerous Oxalate, Cerium (III) Oxalate, 139-42-4, 1570-47-7

CERIUM OXALATE (CERIUM(III) OXALATE HYDRATE) 

Chemical Name: Cerium(III) Oxalate Hydrate / Cerium Oxalate / Cerous Oxalate
CAS Number: 139-42-4 / 1570-47-7
EC Number: 205-348-4
UN Number: 3077 (Environmentally hazardous substance)

1. PRODUCT IDENTIFICATION AND CHEMICAL IDENTITY

CHEMICAL STRUCTURE AND DESCRIPTION:

Cerium Oxalate (Ce₂(C₂O₄)₃·xH₂O) is the oxalate salt of cerium in the +3 oxidation state. The compound has a complex structure where three oxalate ligands (C₂O₄²⁻) coordinate to two cerium ions (Ce³⁺). It is commercially available typically in hydrated form (xH₂O, typically x=9 or 10). Cerium Oxalate has extremely low solubility in water, making it an ideal precipitation agent for the separation and purification of rare earth elements. Its thermal decomposition directly yields cerium oxide (CeO₂), making it the preferred precursor for high-purity CeO₂ production.

Structural Features:

• Coordination complex of oxalate ligands with cerium ions

• Very low solubility in water (suitable for precipitation)

• Direct conversion to CeO₂ upon thermal decomposition

• Monoclinic crystal structure in hydrated form

• Not hygroscopic

2. PHYSICAL AND CHEMICAL PROPERTIES

Thermal Decomposition Reaction:
Ce₂(C₂O₄)₃ → 2CeO₂ + 2CO₂ + 4CO (300-600°C)

Cerium Oxalate is a white, odorless, crystalline powder with very low solubility in water. Its density is approximately 3.7 g/cm³. When heated, it decomposes directly to cerium oxide (CeO₂) without melting. The thermal decomposition produces carbon monoxide and carbon dioxide gases along with CeO₂ formation. The gas evolution during decomposition results in a porous structure, which is advantageous for producing high-surface-area CeO₂.

3. SOLUBILITY PROFILE

Cerium Oxalate has very low solubility in water and organic solvents. It dissolves in hot concentrated acids (hydrochloric, nitric, sulfuric) forming cerium salts. Its solubility may increase in the presence of oxalic acid due to complex formation. It is insoluble in alkalis. This solubility profile makes it an excellent precipitant for rare earth separation and purification processes.

4. CHEMICAL PROPERTIES AND REACTIONS

Cerium Oxalate is a typical rare earth oxalate. Its thermal decomposition is the most important property for high-purity cerium oxide production. Upon heating, it first loses water of crystallization, then the oxalate ions decompose to form CeO₂, CO₂, and CO. It dissolves in hot acids. Due to oxalate ions, it can form stable complexes with transition metals. It may exhibit photochemical activity when exposed to UV light.

Key Chemical Reactions:

Thermal Decomposition:
Ce₂(C₂O₄)₃ → 2CeO₂ + 2CO₂ + 4CO (300-600°C)

Acid Dissolution:
Ce₂(C₂O₄)₃ + 6HCl → 2CeCl₃ + 3H₂C₂O₄

Precipitation Reaction:
2Ce³⁺ + 3C₂O₄²⁻ → Ce₂(C₂O₄)₃ ↓

5. SPECIFICATIONS (TECHNICAL AND HIGH PURITY)

Cerium Oxalate is manufactured in various grades from technical (≥ 98%) to high purity (≥ 99.999%). High purity grades (99.99% and above) are essential for optical, electronic, and research applications where trace impurities significantly affect performance. Loss on ignition corresponds to the conversion of hydrated oxalate to CeO₂. Technical grades are suitable for metallurgical and general industrial applications.

6. APPLICATIONS AND INDUSTRIAL USES

6.1. Cerium Oxide (CeO₂) Production (Most Important Application)

Cerium Oxalate is the most important and widely used precursor for CeO₂ production. Its thermal decomposition directly yields cerium oxide, and the gas evolution during the process results in high-surface-area, porous CeO₂ particles. The oxalate precursor provides more controlled particle morphology and size compared to carbonate or hydroxide precursors.

CeO₂ Production Pathway:
Ce₂(C₂O₄)₃·xH₂O → Calcination (300-600°C) → CeO₂ + CO₂ + CO

6.2. Research and Laboratory Applications

6.3. Nanotechnology and Advanced Materials

6.4. Electrochemical Applications

6.5. Ceramics and Glass Applications

6.6. Defense and Specialized Optics

7. ALTERNATIVE / EQUIVALENT PRODUCTS

8. SECTOR SUITABILITY TABLE

9. COMMON NAMES

• Cerium-based precipitant

• White cerium salt

• CeO₂ precursor

• Cerium oxalate crystal

• Cerous oxalate

• Rare earth oxalate

10. PRODUCTION PROCESS

Reaction Equation:
2CeCl₃ + 3H₂C₂O₄ → Ce₂(C₂O₄)₃ ↓ + 6HCl
or
2Ce(NO₃)₃ + 3H₂C₂O₄ → Ce₂(C₂O₄)₃ ↓ + 6HNO₃

Production Types: Technical and high purity grades

Major Producing Countries: China, India, United States, Russia, Japan

Commercial Purity: Ranges from 98% to 99.999%

11. SAFETY AND TOXICOLOGY

SPECIAL WARNINGS: Cerium Oxalate is generally considered of low toxicity. However, oxalate ions can form insoluble complexes with calcium, so calcium metabolism may be affected if ingested. It may cause irritation to skin, eyes, and respiratory tract. Inhalation of dust should be avoided. The compound is not classified as carcinogenic. Environmental release should be prevented as it is classified as an environmentally hazardous substance (UN 3077).

12. TRANSPORT INFORMATION

Cerium Oxalate is classified as an environmentally hazardous substance under UN 3077. Release into the environment must be prevented during transport. Proper packaging and labeling are required for international transport.

13. REGULATORY INFORMATION

Cerium Oxalate is registered in all major industrial markets. KKDİK registration is required for use in Turkey. It is classified under customs tariff code 2846.90.00.00.19. Proper import/export documentation is required for international trade.

14. STORAGE AND HANDLING

Handling Notes:

• Avoid dust formation and inhalation

• Avoid skin and eye contact (use protective gloves and safety goggles)

• Use in well-ventilated areas

• Keep away from acids and oxidizers

• Prevent environmental release

• Avoid high temperatures (thermal decomposition begins at ~300°C)

• Use under fume hood or with adequate ventilation

15. FIRE-FIGHTING MEASURES

Cerium Oxalate is not a flammable substance. In case of fire, protective clothing and SCBA must be used. Thermal decomposition may release carbon monoxide, carbon dioxide, and cerium oxide fumes.

16. ACCIDENTAL RELEASE MEASURES

In case of spillage, appropriate personal protective equipment must be worn. Clean up using dry methods. Environmental release must be prevented as it is classified as UN 3077.

17. FIRST AID MEASURES

Special Notes:

• Oxalate ions form insoluble complexes with calcium; calcium metabolism may be affected

• In case of ingestion, calcium gluconate or calcium lactate may be administered

• Medical personnel should be informed about oxalate exposure

18. RAW MATERIALS AND DOWNSTREAM PRODUCTS

18.1. Raw Materials (Upstream)

18.2. Downstream Products

19. QUALITY CONTROL PARAMETERS

20. SUMMARY AND CRITICAL WARNINGS

SUMMARY:

Cerium Oxalate (Ce₂(C₂O₄)₃·xH₂O, CAS 139-42-4 / 1570-47-7) is a white, odorless, crystalline powder with very low solubility in water. It is the oxalate salt of cerium in the +3 oxidation state. The molecular weight is approximately 544.29 g/mol (depending on hydration degree) and density is approximately 3.7 g/cm³. At 300-600°C, it thermally decomposes directly to cerium oxide (CeO₂). Its extremely low solubility in water makes it an ideal precipitant for the separation and purification of rare earth elements.

Its most important application is as the primary precursor for CeO₂ production. The thermal decomposition of cerium oxalate yields high-purity cerium oxide used in optics, catalysts, polishing applications, and automotive emissions control. The oxalate precursor provides more controlled particle morphology and size compared to carbonate or hydroxide precursors. It is also used in research laboratories as a precipitation agent, in nanotechnology for nanoparticle synthesis, and in ceramics and glass applications as an additive.

The compound is classified as an environmentally hazardous substance under UN 3077 and is a marine pollutant. While generally considered of low toxicity, oxalate ions can form insoluble complexes with calcium, affecting calcium metabolism. It may cause skin, eye, and respiratory tract irritation. It should be stored in cool, dry, well-ventilated areas away from acids and oxidizers. The shelf life is 24-36 months under proper storage conditions.

Key Properties:

Major Application Areas:

Key Safety Points:

• ENVIRONMENTALLY HAZARDOUS: UN 3077

• IRRITANT: Skin, eye and respiratory irritation

• OXALATE TOXICITY: May affect calcium metabolism

• STORAGE: Cool, dry, well-ventilated

• INCOMPATIBLE: Strong acids, oxidizers, heat

• PROTECTIVE EQUIPMENT: Gloves, safety goggles, dust mask

• ECOTOXIC: Marine pollutant

CRITICAL WARNINGS:

1. UN 3077 CLASSIFICATION: Cerium Oxalate is classified as an environmentally hazardous substance under UN 3077. Release into the environment during transport, storage, or disposal must be strictly prevented. It is listed as a marine pollutant.

2. PRIMARY PRECURSOR FOR CeO₂: Cerium Oxalate is the most important and widely used precursor for CeO₂ production. Its thermal decomposition directly yields cerium oxide and the gas evolution during decomposition (CO₂, CO) results in high-surface-area, porous CeO₂ particles. This makes it ideal for catalyst and adsorbent applications.

3. CONTROLLED PARTICLE MORPHOLOGY: The oxalate precursor provides more controlled particle morphology and size compared to carbonate or hydroxide precursors. By adjusting calcination conditions (temperature, time, atmosphere), the properties of CeO₂ particles can be optimized for specific applications.

4. OXALATE TOXICITY: Oxalate ions form insoluble calcium oxalate complexes in the body, which can reduce calcium absorption and contribute to kidney stone formation. In case of ingestion, calcium gluconate or calcium lactate administration may be necessary.

5. THERMAL DECOMPOSITION CHEMISTRY: The thermal decomposition of cerium oxalate occurs in two stages: loss of water of crystallization (100-200°C) followed by oxalate ion decomposition (300-600°C). The decomposition atmosphere (oxidizing or inert) affects the oxidation state and surface properties of the final CeO₂ product.

6. PRECIPITATION EFFICIENCY: The extremely low solubility of cerium oxalate in water (very low Ksp) means that precipitation is practically quantitative. This property makes it ideal for gravimetric analysis and industrial separation processes for rare earth elements.

7. NOT HYGROSCOPIC: Its non-hygroscopic nature provides ease of storage and handling. It is more stable against moisture compared to other cerium salts.

8. CALCINATION EXOTHERM: The thermal decomposition of oxalate is an exothermic reaction. Temperature control must be carefully managed in large-scale calcination operations.

9. CUSTOMS CLASSIFICATION: The correct customs tariff code is 2846.90.00.00.19. Correct classification is essential for international trade, with potential country-specific restrictions for rare earth compounds.

10. CAS NUMBERS: Two CAS numbers exist for Cerium Oxalate. 139-42-4 is generally used for the anhydrous or low-hydrate form, while 1570-47-7 is used for the hydrated form (typically Ce₂(C₂O₄)₃·10H₂O). Selection of the correct CAS number depends on the hydration degree of the product.

Important Disclaimer: This Technical Data Sheet (TDS) is for informational purposes only. The information provided is based on available data and is believed to be accurate. However, the user is solely responsible for determining the suitability of the product for their specific applications and for complying with all applicable regulations and safety requirements. For complete safety, handling, storage, and regulatory compliance information, always refer to the official Safety Data Sheet (SDS/MSDS) provided by the manufacturer/supplier. Users are responsible for testing the product in their own processes and applications. All local, national, and international regulations must be followed when working with Cerium Oxalate. Due to its oxalate toxicity and environmental classification, a detailed risk assessment and handling procedure should be established prior to use.