Cerium Oxide

Rare Earth Oxides

Cerium Oxide, chemically existing in two primary forms—cerium(III) oxide (Ce₂O₃, rare earth sesquioxide) and cerium(IV) oxide (CeO₂, ceria, the dominant stable form under ambient conditions)—is a versatile and critical inorganic compound in the rare earth oxide family. Distinguished by its unique ability to switch between Ce³⁺ and Ce⁴⁺ oxidation states (a trait called “redox duality”), it combines high chemical stability, thermal resistance, and optical transparency—setting it apart from single-valence Rare Earth Oxides like lanthanum oxide (La₂O₃, only +3) or neodymium oxide (Nd₂O₃, only +3). Unlike soluble cerium salts (e.g., cerium nitrate, cerium acetate), Cerium Oxide (primarily CeO₂) exhibits near-zero aqueous solubility and exceptional inertness, making it ideal for applications requiring long-term stability in harsh environments (e.g., high temperatures, corrosive atmospheres). With base purities ranging from 99% (technical grade) to 99.999% (ultra-high purity), and controlled Ce³⁺/Ce⁴⁺ ratios (0.1%–5% Ce³⁺ for most grades, up to 30% for specialized redox-active grades), it is widely used in polishing, catalysis, ceramics, electronics, and environmental protection.

Commercially, Cerium Oxide is categorized by oxidation state, purity, particle size, and morphology (nanopowder, micron powder, or sintered pellets) to meet diverse application needs. Technical Grade (primarily CeO₂, purity 99.0%–99.5%, particle size 1–5 μm, micron powder) prioritizes cost-efficiency for industrial uses like glass polishing (precision grinding of optical lenses), ceramic sintering aids (lowering firing temperature of zirconia ceramics), and as a raw material for cerium metal production. Reagent Grade (CeO₂ content ≥99.9%, controlled Ce³⁺<1%, particle size 0.5–2 μm) meets laboratory standards for analytical chemistry (e.g., reference material for cerium analysis), small-scale catalyst synthesis (as a support for noble metals), and optical coating research. High-Purity Grade (CeO₂ content ≥99.99%, Ce³⁺ 0.1%–0.5%, particle size 50–200 nm, nanopowder) targets high-performance applications: including automotive three-way catalysts (TWC, for NOₓ reduction), solid oxide fuel cell (SOFC) electrolytes, and UV-blocking additives for plastics. Ultra-High Purity Grade (CeO₂ content ≥99.999%, Ce³⁺ <0.1%, particle size 10–50 nm, monodisperse nanopowder) is a niche grade for semiconductor and optoelectronic applications, with trace impurities strictly controlled (e.g., <5 ppb heavy metals, <3 ppb Si/Al/Ca, <1 ppb other rare earths) to avoid performance defects. At standard temperature and pressure, pure CeO₂ appears as white to pale yellow crystalline powder, while Ce₂O₃ (unstable in air, oxidizing to CeO₂ over time) is pale yellow to pink. The color of commercial CeO₂ varies slightly with Ce³⁺ content—higher Ce³⁺ imparts a faint yellow hue. Purity and Ce³⁺/Ce⁴⁺ ratio are verified via X-ray photoelectron spectroscopy (XPS) for valence analysis, inductively coupled plasma mass spectrometry (ICP-MS) for elemental purity, and X-ray diffraction (XRD) for crystal structure (fluorite structure for CeO₂, corundum structure for Ce₂O₃).

Physically, Cerium Oxide exhibits traits tailored to its oxidation state and application requirements. Cerium(IV) oxide (CeO₂) has a molecular weight of 172.12 g/mol, a high bulk density of ~7.13 g/cm³ (higher than most rare earth oxides), and a melting point of 2600°C—one of the highest among rare earth oxides, ensuring thermal stability in high-temperature processes. Its particle size strongly influences performance: micron-scale powder (1–5 μm) has low specific surface area (5–15 m²/g), ideal for polishing (abrasive action), while nanopowder (10–50 nm) has a high specific surface area (50–200 m²/g), enhancing catalytic activity. Optically, CeO₂ is transparent in the visible range (400–700 nm) and exhibits strong UV absorption (200–380 nm) due to Ce⁴⁺ → O²⁻ charge transfer, making it a key additive for UV-protective coatings and plastics. Thermally, it is resistant to sintering up to 1000°C (for nanopowder) and does not decompose below its melting point. It exhibits minimal hygroscopicity (<0.1% moisture absorption at 60% humidity), preventing caking and ensuring consistent performance during storage. Notably, CeO₂ has high oxygen storage capacity (OSC)—it can reversibly absorb and release oxygen via Ce³⁺/Ce⁴⁺ redox cycles, a property critical for catalytic applications like automotive TWCs.

Chemically, Cerium Oxide’s defining feature is its redox duality between Ce³⁺ and Ce⁴⁺. In air, Ce₂O₃ (unstable) rapidly oxidizes to CeO₂, while CeO₂ can be reduced to Ce₂O₃ under high-temperature reducing conditions (e.g., H₂ or CO atmosphere above 800°C). This redox cycle enables its oxygen storage capacity: in TWCs, CeO₂ absorbs oxygen during lean-burn conditions (high O₂) and releases it during rich-burn conditions (low O₂), maintaining optimal oxygen levels for pollutant oxidation. It is resistant to most acids (except concentrated HCl, which reacts to form CeCl₃) and bases, with no reaction with water or carbon dioxide at room temperature—ensuring stability in atmospheric and industrial environments. It forms solid solutions with other rare earth oxides (e.g., Gd₂O₃, Sm₂O₃) to enhance ionic conductivity, used in SOFC electrolytes. When heated with carbon or reducing agents, it undergoes carbothermal reduction to produce cerium metal (CeO₂ + 2C → Ce + 2CO↑), a key step in cerium metallurgy. It exhibits no acute toxicity and is biocompatible, making it suitable for biomedical applications like dental polishing and drug delivery.

The industrial production of Cerium Oxide primarily uses cerium-rich raw materials, such as cerium carbonate (Ce₂(CO₃)₃), cerium nitrate (Ce(NO₃)₃), or mixed rare earth concentrates (bastnasite or monazite), via calcination or precipitation-roasting processes. The process involves five core steps. First, raw material purification: If using mixed rare earth concentrates, solvent extraction (using P507 or C272 extractant) is performed to separate cerium from other rare earths (La, Nd, Pr), yielding a purified cerium salt solution (e.g., Ce(NO₃)₃ or Ce₂(CO₃)₃). If using pure cerium salts, they are dissolved in deionized water and filtered to remove impurities. Second, precipitation (for high-purity grades): The purified cerium solution is reacted with a precipitant (e.g., ammonium carbonate for Ce₂(CO₃)₃, or sodium hydroxide for Ce(OH)₃) at 50–70°C (pH 8–9) to form a cerium precursor precipitate. The precipitate is washed repeatedly to remove residual anions (NO₃⁻, Cl⁻). Third, calcination: The dried precursor (cerium carbonate or hydroxide) is roasted in a muffle furnace or rotary kiln at 800–1200°C for 2–4 hours. For CeO₂ production, calcination is done in air (oxidizing atmosphere) to ensure full conversion to Ce⁴⁺; for Ce₂O₃ (specialized grades), calcination is done in a reducing atmosphere (H₂/N₂ mix) at 900–1100°C. Fourth, milling and classification: The calcined oxide is crushed and milled to the target particle size—micron powder via ball milling, nanopowder via jet milling or sol-gel methods. High-purity grades undergo air classification to ensure narrow particle size distribution. Fifth, quality control: The final product is tested for purity (ICP-MS), Ce³⁺/Ce⁴⁺ ratio (XPS), and particle size (laser diffraction). Ultra-high purity grades undergo additional vacuum annealing (1000°C, 10⁻⁵ mbar) to remove residual impurities.

Cerium Oxide’s applications are driven by its redox duality, thermal stability, and optical properties. In glass polishing, Technical Grade CeO₂ (1–5 μm) is the gold standard for precision optical polishing: it has a hardness (Mohs 6–7) matching glass, enabling scratch-free grinding of lenses, mirrors, and semiconductor wafers—replacing traditional abrasives like alumina due to higher polishing efficiency. In catalysis, High-Purity Grade CeO₂ nanopowder (50–100 nm) is a key component of automotive TWCs: mixed with platinum/palladium, it enhances NOₓ, CO, and hydrocarbon oxidation, reducing vehicle emissions. It is also used in industrial catalysis (e.g., ethanol steam reforming for hydrogen production) due to its oxygen storage capacity. In ceramics, Technical Grade CeO₂ acts as a sintering aid for zirconia ceramics: it stabilizes the cubic zirconia phase and lowers sintering temperature by 150–200°C, improving ceramic density and toughness—used in dental crowns and engine components. In electronics, Ultra-High Purity Grade CeO₂ (10–50 nm) is a gate dielectric material for advanced semiconductors: its high dielectric constant (εᵣ ≈ 26) enables miniaturization of transistor gates. In environmental protection, it is used in water treatment as a photocatalyst: under UV light, CeO₂ generates reactive oxygen species (ROS) that degrade organic pollutants (e.g., dyes, pesticides) with high efficiency. Additionally, it is used in cosmetics as a UV filter (safe alternative to titanium dioxide) and in biomedical applications (e.g., anti-inflammatory coatings for implants) due to its biocompatibility.

Safety-wise, Cerium Oxide has low acute toxicity and is considered safe for most industrial and consumer uses. Technical-grade micron powder may generate respirable dust: long-term inhalation of high concentrations may cause mild lung irritation, so operators should wear N95 dust masks during handling. Nanopowder, due to higher surface area, requires extra care (e.g., fume hoods) to avoid inhalation, though no significant toxicity has been reported in standard applications. It is non-flammable, non-explosive, and does not react with common materials—thermal decomposition occurs only above 2600°C (melting), releasing no toxic gases. Skin or eye contact with powder causes minimal irritation; affected areas can be rinsed with water. Storage should be in a cool (15–25°C), dry (<60% humidity) area in sealed HDPE or paper bags (for micron powder) or vacuum-sealed containers (for nanopowder) to prevent moisture absorption. It should be separated from strong reducing agents (e.g., metal powders) to avoid unwanted reduction. When stored properly, Technical Grade has a shelf life of 5–7 years, High-Purity Grade 3–5 years, and Ultra-High Purity Grade 2–3 years. Expired products may show reduced catalytic activity (detected via oxygen storage capacity tests) or increased particle agglomeration (nanopowder), and should be tested before use.

Descriptive:  WNX employs advanced automated production technology and uses high-quality raw materials to produce high-qualityCerium Oxide.

Key Features:

High Purity:Cerium Oxide contains no impurities from rare earth elements (such as iron, calcium, sodium), and the impurity content is low.

Good Solubility:Cerium Oxide can dissolve rapidly in water and strong acids.

Consistency: The strict batch management in the production ofCerium Oxide ensures stable quality for industrial large-scale production.

Precision polishing: Cerium oxide is the most efficient glass polishing material, widely used in the fine processing of camera lenses, spectacle lenses, optical instruments, semiconductor wafers (chemical mechanical polishing CMP), etc. It can quickly achieve an ultra-smooth surface through both chemical and mechanical actions.

Environmental Catalysis: In the purification of vehicle exhaust (three-way catalytic converter), cerium oxide serves as a key component, effectively storing and releasing oxygen, facilitating the conversion of carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) into harmless carbon dioxide, nitrogen, and water. It is also used in industrial exhaust gas treatment and water-gas shift reactions, among others.

Glass Industry: In the glass manufacturing process, cerium oxide plays multiple roles: (1) Bleaching agent: It oxidizes the green divalent iron ions in the glass into the lighter trivalent iron ions, making the glass more transparent; (2) Clarifying agent: It removes bubbles from the molten glass; (3) UV absorber: It absorbs ultraviolet rays and is used to make sun-protective glass and aerospace windows. It can also combine with titanium dioxide to color the glass.

Energy and Electronics: Due to its ionic conductivity and stability, cerium oxide is an important electrolyte material for solid oxide fuel cells (SOFCs). In the field of electronics, it is used to manufacture electronic ceramic components such as capacitors and piezoelectric ceramics.

1.Neutral labels/packaging (jumbo bag of 1.000kg each net),Two bags per pallet.

2.Vacuum-sealed, then wrapped in air cushion bags, and finally packed into iron drums.

Drum: Steel drums (open-top, 45L capacity, dimensions: φ365mm × 460mm / inner diameter × outer height).

Weight per Drum: 50 kg

Palletization: 18 drums per pallet (total 900 kg/pallet).

Transport Class: Maritime transportation / Air transportation

Custom packaging available upon request