Bio-based Adiponitrile (ADN)

Adiponitrile (ADN) is a critical intermediate for producing hexamethylenediamine (HMDA) and subsequently nylon-6,6, which is widely used in automotive parts, fibers, textiles, and engineering plastics. Traditionally produced via the electrohydrodimerization of acrylonitrile (a fossil-based chemical), ADN production involves hazardous reagents like hydrogen cyanide and requires high energy input.

Bio-based routes aim to decarbonize ADN by producing it from renewable feedstocks such as sugars or lignocellulosic biomass, either through fermentation-to-adipic acid and amination or direct microbial nitrilation pathways.

How Bio-based ADN is Produced

Key Pathways:

1. Adipic Acid → Adiponitrile
• Ferment sugars into bio-adipic acid using engineered microbes.
• Convert adipic acid into ADN via dehydration and amination with ammonia using chemical or electrochemical routes.
2. Direct Microbial Production (Emerging)
• Engineered microorganisms use sugars to produce adiponitrile directly, bypassing acid intermediates. This involves synthetic nitrilation pathways still under active research.
3. Electrochemical Nitrilation from Biomass Intermediates
• Glucose-derived intermediates are converted to ADN via novel electro-organic synthesis with ammonia.

Feedstocks: Corn sugar, cellulosic glucose, or sugarcane molasses. Emerging research explores CO₂ + H₂ pathways for upstream precursors.

Case Study: Genomatica & Aquafil Nylon Platform

Highlights:

• While primarily focused on bio-HMDA, Genomatica’s work involves upstream intermediates like bio-adiponitrile.
• Collaboration supports nylon-6,6 value chain decarbonization.
• Aims to enable drop-in compatibility with current polyamide production systems.

   

Timeline & Outcome:

• 2021: Partnership announced with Aquafil to scale bio-nylon intermediates.
• 2022: Bio-HMDA pilot-scale demonstrations begin.
• 2023: Exploration of full bio-nylon-6,6 route, including precursors like ADN.
• 2024–2025: Expected commercial readiness of integrated value chain, including ADN.

Global Startups Working on Bio-based ADN

• Genomatica (USA) – Synthetic biology platform addressing full nylon monomer suite, including potential bio-ADN.
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• AFYREN (France) – Produces bio-adipic acid from sugar waste, potentially convertible to ADN.
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• Electrochaea (Germany/USA) – Pioneering microbial electrochemical systems to produce nitriles and other chemicals from biomass/CO₂.
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India’s Position

India currently imports all of its adiponitrile and nylon-6,6 intermediates, despite having:

• Strong ethanol and sugar platform.
• Domestic production of adipic acid derivatives from renewable sources under pilot scale.
• R&D at institutions like IIT Bombay, ICT Mumbai, and CSIR-IIP on bio-amination and electrochemical conversion.

Commercialization Outlook

Market & Demand

• Global ADN market: ~$7.8 billion (2024), projected to reach ~$10.5 billion by 2030 (CAGR ~5.1%)
• Applications:
• Nylon-6,6 for engineering plastics, automotive, fiber.
• Intermediates for polyurethanes and amine compounds.

Key Drivers

• Demand for low-carbon nylon in apparel, automotive, and electronics.
• Regulatory pressure to replace cyanide-based processes with safer alternatives.
• Push for EU/US-based localized, bio-based nylon value chains.
• FMCG and automotive OEMs committing to bio-sourced engineering plastics.

Challenges to Address

• Toxicity and Risk: Handling of nitriles and ammonia requires stringent safety protocols.
• Process Complexity: Bio-to-nitrile conversion is chemically intensive or requires novel microbial enzymes.
• Energy Demand: Dehydration and amination are energy-intensive unless paired with green electricity or low-temperature biocatalysis.
• Cost Gaps: Bio-ADN remains 2–3× more expensive than petrochemical ADN without scale.

Progress Indicators

• 2018–2021: Genomatica expands scope to nylon monomers, including ADN pathway.
• 2022: Pilot production of HMDA and related compounds.
• 2023: EU and US funding awarded to develop cyanide-free nitrile chemistry.
• 2024–2025: Expected scale-up announcements from nylon players involving renewable ADN value chains.
• India: IIT Bombay and CSIR exploring electrosynthesis of nitriles from biomass.

Bio-based adiponitrile is at TRL 5–6, with chemical and microbial routes demonstrated at pilot scale. Full drop-in integration for nylon-6,6 is under development, with upstream bio-adipic acid pathways at TRL 7–8.

Conclusion

Bio-based adiponitrile is essential for building a low-carbon, cyanide-free nylon-6,6 supply chain. With Genomatica and other players developing biological and hybrid routes, bio-ADN is moving steadily from R&D into pilot production. India, though currently dependent on imports, has the raw material base, R&D infrastructure, and policy momentum to participate in bio-ADN manufacturing. As technology matures and scale economies kick in, bio-adiponitrile will help transform nylon and engineering plastics into truly circular, climate-smart materials.

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