I. Chemical Nature and Physicochemical Propertie
• Molecular Structure: A cyclic anhydride formed by dehydration of three carboxyl groups at the 1,2,4 positions of a benzene ring (C9H4O5), featuring reactive anhydride groups.
• Physical Properties: White needle-like crystals; melting point 168°C, boiling point 390°C, density 1.54 g/cm³. Slightly soluble in toluene, readily soluble in polar solvents (e.g., acetone), and hydrolyzes slowly in water.
II. Key Production Processes
Liquid-Phase Air Oxidation (Mainstream)
Using pseudocumene as raw material, acetic acid as solvent, and Co-Mn-Br as catalyst, air oxidation at 200°C and 2.0 MPa yields trimellitic acid, which is dehydrated to TMA with a yield of 130% and purity ≥99%.
Nitric Acid Oxidation (Traditional)
Nitric acid oxidizes pseudocumene at 180–205°C and 1.5–3.0 MPa. Simple process but severe corrosion issues, gradually phased out.
Other Processes
Gas-phase oxidation is not industrialized due to low catalyst selectivity; the MGC method uses m-xylene as raw material but requires acid-resistant equipment (HF-BF3 system).
III. Industrial Applications
1. Polymer Materials
• PVC Plasticizer TOTM: Enhances PVC heat resistance and electrical insulation for new energy vehicle cables and high-speed rail interiors.
• Polyimide Resins: Withstand 260°C, applied in 5G chip heat dissipation substrates and aerospace thermal insulation.
2. Functional Chemicals
• Epoxy Curing Agent: Cured products have a Tg of 198°C, used in wind turbine blades and high-voltage insulation.
• Aviation Lubricant Additives: Anti-wear agents maintain lubricity at -50°C to 200°C for turbofan engines.
3. Emerging Fields
Halogen-free flame-retardant polyesters for electronic casings; chain extenders for PLA biodegradables, increasing tensile strength to 90 MPa.
IV. Safety and Storage
Toxicity & Protection: LD50 (oral, rat) 1.5 g/kg. Dust irritates respiratory tract; workplace concentration <1 mg/m³. Use N95 masks and chemical-resistant gloves.
Storage: Seal in dry nitrogen, prevent hydrolysis, separate from amines and oxidants. Use CO2 fire extinguishers.
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