Hexamine (Gas Phase Process) Plant

Hexamethylenetetramine (HMTA), leveraging its unique cage-like molecular structure and physicochemical properties, finds broad applications across multiple fields: Its high thermal stability (decomposition temperature 263°C) and alkaline nature make it a core component in solid fuel combustion accelerants and urinary tract infection antibacterial agents. Its water solubility and controllable decomposition (releasing formaldehyde and ammonia) underpin applications in phenolic resin curing, formaldehyde capture, and explosive performance enhancement. Gas-phase production further amplifies its advantages through high-purity synthesis, nano-scale control, and near-zero wastewater processes, meeting advanced demands in pharmaceuticals (vaccine preservation), environmental protection (air purification), and high-energy materials (nano-HMTA). This synergy between HMTA's physicochemical traits and green manufacturing exemplifies innovation in industrial-ecological integration.

Applications of HMTA

Chemical Industry
- Phenolic Resin Curing Agent: High-purity HMTA from gas-phase method enhances curing efficiency and reduces impurities.
- Rubber Vulcanization Accelerator: Uniform particle size improves vulcanization uniformity in high-performance rubber products (e.g., tires).
Pharmaceuticals
- Antibacterial Agent: High-purity HMTA meets medical standards with minimal solvent residues.
- Vaccine Preservative: Ultra-low moisture content (advantage of gas-phase method) ensures vaccine stability.
Defense & Energy
- Solid Fuel Additive: Nano-sized HMTA (achieved via gas-phase synthesis) boosts combustion efficiency in rocket propellants.
- Explosive Component: High purity reduces risks in RDX-based explosives.
Environment & Advanced Materials
- Formaldehyde Scavenger: High reactivity for air purification systems.
- Nanomaterial Precursor: Direct synthesis of nano-HMTA for carbon composites or catalyst supports.
Other Industrial Uses
- Metal Corrosion Inhibitor: Long-lasting protection due to low impurity levels.
- Textile Flame Retardant: Improved dispersion enhances fire-resistant coatings.

Introduction

Hexamine is a heterocyclic organic compound with the formula (CH2)6N4. It has a cage-like structure similar to adamantine. It is useful in the synthesis of other chemical compounds, e.g. plastics, pharmaceuticals, rubber additives. Hexamine is mainly used in the production of powdery or liquid preparations of phenolic resins and phenolic resin moulding compounds, where it is added as a hardening component. These products are used as binders, e.g. in brake and clutch linings, abrasive products, non-woven textiles, formed parts produced by moulding processes, and fireproof materials. Also hexamine is widely applied in other fields like medicine, histological stains, solid fuel, food additive, organic synthesis chemistry, pesticide, dynamite and so on.

SL-TECH employs Gas-Phase Process, which is featured in feedstocks being charged in the form of gas instead of liquid. On one hand, it enables much less water to be introduced; on the other, the inert gases contained in the formaldehyde feedstock helps to carry off the produced water. As a result, the concentration and crystallization goes more easily with a very small amount of steam. And waste water will be discharged from this plant in a small volume.

Key Features of Gas-Phase Production

Reaction System
- Reactant State: Uses gaseous formaldehyde (HCHO) and ammonia (NH₃) without liquid solvents.
- Reaction Conditions: Operates at high temperatures (120–180°C) with precise temperature control to prevent HMTA decomposition (decomposition starts at ~263°C).
Catalyst Dependency
- Requires acidic or metal oxide catalysts (e.g., ZSM-5 molecular sieve, Al₂O₃-SiO₂) to facilitate the reaction.
- Catalysts are prone to deactivation due to carbon deposition or sintering, requiring frequent regeneration or replacement.
Product Separation Challenges
- Solid HMTA particles are generated, necessitating rapid cooling/condensation or electrostatic precipitation for gas-solid separation.
- Unreacted gases (formaldehyde, ammonia) must be recycled to improve raw material utilization.
Specialized Equipment
- Requires high-temperature and corrosion-resistant reactors (e.g., fixed-bed or fluidized-bed reactors).
- Complex auxiliary systems for gas preheating, quenching, and product collection.

Core Advantages

Advantage	Description
1. Environmental Friendliness	Eliminates liquid wastewater, reducing emissions of formaldehyde and ammonia.
2. Fast Reaction Rate	High gas-phase mass transfer efficiency reduces reaction time to minutes (vs. hours in liquid-phase methods).
3. Energy-Saving Potential	Plasma or microwave-assisted activation lowers energy consumption.
4. Scalability for Continuous Production	Compatible with microreactors or fluidized beds for efficient continuous processes.
5. Controllable Product Properties	Enables synthesis of nano-sized or high-purity HMTA (e.g., pharmaceutical grade) via temperature and gas-phase condition adjustments.

Limitations

Low Technological Maturity: Currently limited to lab-scale research with no successful industrial applications.
High Energy and Economic Costs: High-temperature reactions and complex equipment increase capital and operational expenses.
Short Catalyst Lifespan: Carbon deposition and sintering reduce continuous operation time, raising maintenance costs.
Low Product Purity: Requires additional purification steps (e.g., recrystallization) to meet industrial standards.

Optimization Strategies

Catalyst Innovation
- Develop high-stability, anti-coking nanocatalysts (e.g., metal-zeolite composites).
Reactor Design
- Implement microwave heating or plasma activation for precise temperature control and energy efficiency.
- Use fluidized-bed reactors to enhance gas-solid contact.
Separation Technology Upgrades
- Improve solid product collection via in-situ crystallization or electrostatic adsorption.
Process Integration
- Combine with biomass-derived formaldehyde production to reduce carbon footprint.

The gas-phase HMTA production process offers environmental benefits and high reaction efficiency but faces challenges such as high-temperature decomposition risks, catalyst instability, and industrialization barriers. Future breakthroughs in materials science and reaction engineering are critical to advancing this technology from lab-scale research to industrial application.

Technical Features

● The investment of gas phase process is much lower. For 5000TPA, gas phase process only needs one production line.

● The waste water is less than that of the Liquid phase process. The reason is that Liquid phase process need absorb water then dewater to produce hexamine.

● Gas phase process is continuous production operated by DCS system, so less operators are needed.

Hexamine Specification

S/N	Item	Index
1	Hexamine, wt%	99.5
2	Water, wt%	0.14
3	Ash, wt%	0.018
4	Appearance of aqueous hexamine solution	Clear and transparent
5	Heavy metal, wt% (as per Pb)	0.001
6	Chloride, wt% (as per Cl+)	0.015
7	Sulfate, wt% (as per SO42-)	0.023
8	Ammonium salt, wt% (as per NH4+)	0.001