By Richie Lin    Photo：CANVA

Trimethylaluminium (TMA) is a highly reactive compound primarily used in industrial applications requiring methylating agents, catalysts, or thin-film deposition. Here are the key industries that utilize TMA:

1. Semiconductor and Electronics Industry

Application:

• Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD):
  • TMA is extensively used as a precursor for depositing aluminium-containing thin films
  • These films are crucial in manufacturing:
    • Microprocessors
    • Memory chips (DRAM, NAND)
    • LED substrates
    • Display screen

2. Renewable Energy Industry

Application:

• Solar Cell Manufacturing:
  • TMA is used to deposit aluminium oxide layers via ALD or CVD, enhancing the efficiency of photovoltaic cells.
• Energy Storage Systems:
  • Aluminium oxide coatings protect battery electrodes, particularly in lithium-ion batteries, from degradation.

Since TMA is widely used in the manufacturing of semiconductor and energy industries, it will be transported constantly between different countries. And TMA is highly active and dangerous, so the transportation and storage is strictly regulated. Below are the basic procedures for references:

1. International Transportation of Trimethylaluminium:

A. Classification and Regulatory Information:

• UN Number: UN 3394
• Proper Shipping Name: TRIMETHYLALUMINIUM, PYROPHORIC
• Hazard Class: 4.2 (Spontaneously Combustible Substances)
• Secondary Hazard Class: 4.3 (Dangerous When Wet)
• Packaging Group: I (Great Danger)
• Label Requirements:
  • Flammable Solid (4.2)
  • Dangerous When Wet (4.3)
  • Toxic (6.1), if applicable

B. Packaging Requirements:

• Materials:
  • Use corrosion-resistant containers (stainless steel or high-density polyethylene) equipped with tight-sealing valves.
  • The packaging must prevent exposure to air, moisture, and ignition sources.
• Container Types:
  • UN-certified drums or cylinders with pressure relief systems.
  • Pressure-tested and certified containers for pyrophoric liquids.
  • Use secondary containment to prevent leaks and spills.
• Packing Method:
  • Pack under inert gas (e.g., nitrogen or argon) to prevent moisture contact and oxidation.
  • Include absorbent materials capable of neutralizing spills in case of leakage.

C. Mode-Specific Transport Guidelines:

1. Sea Transport (IMDG Code):
   • Class: 4.2 (Spontaneously Combustible Substances)
   • Segregation: Keep away from oxidizers, acids, and water-reactive materials.
   • Ventilation: Ensure proper ventilation to prevent vapor accumulation.
   • Emergency Procedures: Follow IMDG Emergency Schedule (EmS) guidelines for firefighting and spill control.
2. Air Transport (IATA DGR):
   • Classification: Class 4.2 and 4.3
   • Packaging: Special UN-approved cylinders or drums.
   • Limitations: Only specific airlines and cargo aircraft are permitted to transport pyrophoric materials.
   • Documentation: Include Material Safety Data Sheet (MSDS) and Emergency Response Information.
   • Handling: Store in a designated hazardous materials compartment.

2. Storage of Trimethylaluminium:

A. Storage Requirements:

• Location:
  • Store in a designated, fire-resistant area away from populated areas.
  • Maintain a controlled temperature environment to prevent overheating.
  • Store away from sources of ignition, moisture, acids, and oxidizers.
• Temperature Control:
  • Maintain storage temperature between 15°C to 25°C (59°F to 77°F).
  • Avoid temperature fluctuations to prevent container pressure buildup.
• Ventilation:
  • Provide mechanical ventilation to disperse any vapors.
  • Use explosion-proof equipment and ensure ventilation meets ATEX or NFPA 69 standards.
• Inert Atmosphere:
  • Store under an inert gas blanket (e.g., nitrogen or argon) to prevent oxidation.
  • Ensure the gas supply is continuously monitored to maintain positive pressure.

B. Fire Protection:

• Fire Extinguishers:
  • Use Class D dry powder extinguishers (e.g., Met-L-X or Lith-X) designed for pyrophoric metal fires.
  • Water, CO₂, and foam extinguishers are ineffective and can exacerbate fires.
• Fire Suppression System:
  • Install an automatic fire suppression system using dry chemical agents.
  • Ensure emergency shut-off valves for quick isolation.
• Emergency Plan:
  • Develop and implement a comprehensive emergency response plan.
  • Train personnel on handling fires involving pyrophoric materials and gas leaks.

C. Labeling and Documentation:

• Labels:
  • Clearly mark all containers with:
    • UN number (UN 3394)
    • Hazard class labels (4.2, 4.3, 6.1 if applicable)
    • Pyrophoric and Dangerous When Wet placards
• Documentation:
  • Maintain up-to-date Safety Data Sheets (SDS) for all stored containers.
  • Ensure emergency contact information is prominently displayed.
• Inspection and Maintenance:
  • Conduct regular inspections of storage containers and valves for leaks or damage.
  • Replace any damaged containers immediately and dispose of contents as hazardous waste.

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