Pyrophoric materials: Properties, industrial applications and safety precautions

Introduction

Pyrophoric materials are substances that, when in contact with air, ignite spontaneously, which can cause fires and explosions if not handled properly. This property, although dangerous, makes them essential components in different industries, such as pharmaceuticals, aerospace, and agriculture. They are applied in the synthesis of chemical compounds to the manufacture of self-igniting devices, such as flares and fireworks.

In addition, some pyrophoric reagents play a key role in catalytic processes and scientific research. However, their handling requires rigorous safety protocols to avoid accidents. This article details what pyrophoric materials are, their main industrial applications and the risks associated with their use, as well as the necessary measures for their safe storage and handling in work and research environments.

What are pyrophoric materials and how do they work?

Pyrophoric materials are highly reactive substances that ignite spontaneously on contact with air, usually at temperatures of 54.4 °C (130 °F) or less. This property is due to their vigorous reaction with oxygen or water vapor, which generates a rapid release of energy in the form of heat and flame. Common pyrophoric materials include organolithium compounds, silanes and certain alkali metals, as well as elements such as phosphorus, sulfur, and arsenic¹.

Their operation is based on the rapid oxidation that occurs when these materials come into contact with air or moisture. In many cases, this reaction can generate flammable or corrosive by-products, increasing the risk of fire and explosion. In addition, pyrophoric materials can occur in different physical states, such as solids, liquids or gases, which influences the way they must be handled and stored.

Due to their hazardous nature, their handling requires strict safety controls, including physical barriers, personal protective equipment (PPE) and specific storage protocols. In laboratories and industries, they are often kept in flammable solvent solutions, increasing the need for precautionary measures to avoid incidents.

Properties of pyrophoric materials

Pyrophoric materials have a high reactivity due to their tendency to react spontaneously with oxygen in the air or with moisture, generating heat and, in many cases, igniting instantaneously. This property is due to their chemical instability and their ability to oxidize rapidly, which results in the release of a significant amount of thermal energy.

These materials can be in the form of solids, liquids or gases, and are frequently used in flammable solvent solutions, which further increases the risk of fire. Examples of pyrophoric materials include organolithium compounds, metal hydrides and certain finely divided metals, such as powdered aluminum or Raney’s nickel².

They represent very important compounds for the chemical industry, due to properties such as high reactivity, for the development of materials that require specialized treatment and rigorous control to avoid serious accidents.

Industrial applications of pyrophoric materials

• Catalysts in chemical processes: Pyrophoric materials, such as organometallic compounds, are used as catalysts in advanced chemical reactions. Due to their high chemical reactivity, they are used to accelerate industrial processes such as polymerization and the synthesis of pharmaceutical products.
• Production of specialty metal alloys: Some pyrophoric metals, such as titanium and zirconium powder, are used in the manufacture of high-strength alloys. These alloys are used in aerospace, automotive and high-performance equipment.
• Manufacture of electronic devices: They are used in the synthesis of semiconductor materials and in the deposition of thin films in integrated circuits. Pyrophoric gallium and indium compounds are essential in microelectronics.
• Ignition systems and pyrotechnics: Pyrophoric metal powders, such as finely divided iron, are used in ignition mechanisms in security systems, flares and pyrotechnic devices, due to their ability to ignite on contact with oxygen.
• Hydrogen generation in fuel cells: Some pyrophoric compounds, such as metal hydrides, are used in the generation of controlled hydrogen for fuel cells, which makes them key to the development of clean energy.
• Surface treatment and coatings: Used in chemical vapor deposition (CVD) to coat materials with ultra-thin protective layers that improve corrosion and wear resistance in the aerospace and automotive industries.
• Synthesis of advanced nanomaterials: They are applied in the manufacture of nanoparticles with applications in biomedicine, sensors and advanced materials, thanks to their controlled reactivity in inert atmospheres.

Safety precautions when handling pyrophoric materials

Personal Protective Equipment (PPE)

• Wear safety glasses with side shields or splash goggles to avoid contact with eyes.
• Use face shields and safety shields in reactions with high risk of ignition or explosion.
• Wear nitrile gloves under neoprene gloves for better fire resistance.
• Wear flame retardant gowns and avoid flammable synthetic clothing³.

Safe handling

• Perform pre-tests with inert substances to practice the technique.
• Never work alone with pyrophoric materials; use the buddy system.
• Keep the work area free of flammable materials and perform transfers under a fume hood.
• Avoid volumes greater than 20 mL with a syringe; prefer the cannula technique.

Storage and disposal

• Store the reagents under inert gas or in suitable solvents, avoiding exposure to air.
• Correctly label containers and check them periodically.
• Deactivate pyrophoric residues with hydroxyl solvents before disposal.

Emergency procedures

• Have suitable fire extinguishing agents (class D for combustible metals) available.
• Safety showers and eyewash facilities in the laboratory.
• Maintain absorbent materials such as powdered lime or dry sand for spill control.
• Act quickly in case of skin contact, using stop, drop and roll techniques.

Conclusions

Due to their high reactivity and usefulness in advanced processes, pyrophoric materials can be considered both a challenge and an opportunity in the industrial field. Their ability to ignite spontaneously in contact with air requires rigorous handling and strict safety measures to prevent fires and explosions. On the other hand, their range of applications, for example in the synthesis of catalysts and in ignition systems, demonstrate their essentiality for technological development.

Handling pyrophoric materials requires a rigorous approach combining technical knowledge, safety protocols and specialized preventive measures. Their high reactivity makes them essential in numerous industrial and scientific applications, but they also involve significant risks if not handled correctly.

The implementation of safety procedures, such as the use of personal protective equipment, storage in controlled atmospheres and personnel training, is key to minimizing the risk of fires and explosions. In addition, the adoption of a safety culture in laboratories and industries makes it possible to take advantage of their properties without compromising the integrity of the facilities or the safety of the operators.

References

1. https://www.k-state.edu/safety/programs/lab/labsafety/topics/specifichazards/pyrophoricMaterials.html
2. https://ehs.stanford.edu/reference/information-on-pyrophoric-compounds
3. https://ehs.princeton.edu/laboratory-research/chemical-safety/reactive-materials/pyrophoric-materials