Acrylonitrile, 2-propenenitrile, CAS 107-13-1, is a reactive monomer with a boiling point of 77.3 °C, a closed-cup flash point of -1 °C, a vapour pressure of 11.7 kPa at 20 °C, and explosive limits of 3.0–17.0 vol% in air. The stabilised merchant product typically contains 35–50 mg/kg monomethyl ether hydroquinone to suppress radical polymerisation. In China, acrylonitrile is supplied to ABS, SAN, acrylic fibre, acrylamide, nitrile rubber, and adiponitrile producers, and the supplier qualification process is a process-capability audit rather than a commercial negotiation. Seven checks are required before a supply agreement is countersigned.

How to Qualify an Acrylonitrile Supplier in China: 7 Checks Before You Sign

The qualification logic below treats each check as a rejection boundary. The supplier either provides the specified manufacturing, analytical, stability, logistics, regulatory, supply-chain, and audit evidence, or the tender is closed. The checks are ordered from process chemistry to governance because the first two defects are not correctable by documentation.

What Does the Ammoxidation Reactor Reveal About Selectivity and Nitrile Yield?

Production route and catalyst age are evaluated first. The dominant industrial route is propylene ammoxidation over a bismuth-molybdenum oxide fluidised-bed catalyst at 400–450 °C and 50–200 kPa gauge. The molar feed ratio for propylene, ammonia, and air is maintained near 1:1.2:9.5. The supplier audit should capture six months of hourly reactor data, not a single-month average. The parameters include catalyst inventory, bed age, top and bottom bed temperatures, oxygen-to-ammonia ratio, reactor effluent acetonitrile concentration, and recovery extractive-distillation column bottom temperature.

Catalyst age controls selectivity. As the bismuth-molybdenum oxide bed depletes, the supplier typically raises the reaction temperature or air ratio; this shift increases acetonitrile and carbon dioxide by-products. A supplier should state catalyst age as a percentage of vendor life and the actual acetonitrile concentration in reactor effluent. If catalyst life exceeds 60% and acetonitrile in the final product rises above 150 mg/kg, the material is outside typical polymer-grade limits. The audit also verifies that off-gas hydrogen cyanide is incinerated at a minimum 850 °C or converted to acetone cyanohydrin, not vented. Published operating data indicate that a bed-temperature excursion of +5 °C in bismuth-molybdenum fluidised-bed ammoxidation can increase acetonitrile concentration by 20–40 mg/kg, although site-specific catalyst formulations require separate validation.

Impurity profile and analytical methods form the second check. Obtain the last six months of COA data generated by the supplier’s QC laboratory. A polymer-grade acrylonitrile COA aligned with GB/T 7717.1-2008 typically records purity ≥99.5 wt%, water 0.20–0.45 wt%, acetonitrile ≤150 mg/kg, acrolein ≤10 mg/kg, and hydrogen cyanide ≤5 mg/kg. Organic impurities are determined by gas chromatography with flame ionisation detection under GB/T 7717.2-2008; water is determined by Karl Fischer titration under GB/T 6283. The audit should compare the supplier’s reported values with the downstream tolerance of the plant.

In ABS graft emulsion polymerisation, acetonitrile above 150 mg/kg can act as a chain-transfer impurity and narrow molecular weight distribution; acrolein above 10 mg/kg can retard initiation and generate colour bodies in acrylic fibre. Acetonitrile at 150 mg/kg in the monomer feed can reduce the number-average molecular weight of SAN copolymer by 5–10% relative to a 50 mg/kg baseline, depending on initiator half-life and reactor temperature. Published data for this specific configuration is limited; therefore, downstream sites validate their own suppression threshold in a 1 L glass reactor before setting the rejection limit. If the COA values are returned as “< detection limit” without specifying detection limits, the contract should require the exact limit of quantification for each method.

Stabiliser Concentration, Oxygen Control, and Storage Boundary Conditions

Stabiliser concentration, oxygen control, and storage boundary conditions are examined third. MEHQ concentration must be measured at the supplier’s loading rack and at customer receipt. The accepted merchant range is 35–50 mg/kg. Below 35 mg/kg, the stabiliser is insufficient for prolonged storage; above 50 mg/kg, downstream free-radical initiation may be delayed or product colour may increase. Storage tanks and delivery tank containers should be maintained below 25 °C, with a maximum excursion of 30 °C for short transfer periods. Vapour spaces in fixed-roof tanks should be inerted with nitrogen to keep oxygen below 5 vol%, because acrylonitrile vapour is flammable across 3.0–17.0 vol% in air. The supplier should provide nitrogen purity and oxygen analyser calibration records. A tank that has been open to atmospheric air for more than 24 h should be sampled for polymer fines and MEHQ content before loading.

Logistics and transfer compatibility are reviewed fourth. Acrylonitrile is classified as UN 1093, Class 3, Packing Group I. Bulk transport should be in dedicated stainless-steel tank containers or lined carbon steel with nitrogen padding and pressure-relief settings appropriate to the vapour pressure at 40 °C. Transfer pumps should be explosion-proof and bonded. Before loading, the supplier should supply a wash certificate showing no previous cargo of chlorine, organic peroxides, acids, or oxidising agents. For packaged exports, UN 1A1 steel drums with a rust-preventive interior liner or equivalent should be used. The loading temperature should be recorded at the rack and should not exceed 25 °C. The delivery documents should include the bill of lading temperature, seal numbers, and the MEHQ concentration at loading.

When the Supplier Cannot Demonstrate REACH Article 31 Exposure Scenario Compliance

Regulatory alignment is the fifth check. The supplier’s safety data sheet must reflect the current GHS classification: H225 Highly flammable liquid and vapour, H301 Toxic if swallowed, H311 Toxic in contact with skin, H315 Causes skin irritation, H318 Causes serious eye damage, H335 May cause respiratory irritation, and H350 May cause cancer. The safety data sheet must state CAS 107-13-1, UN 1093, Packing Group I, and the MEHQ stabiliser concentration. For shipments to the EU, REACH (EC) No 1907/2006 Article 31 requires an extended safety data sheet with exposure scenarios; the supplier must provide the legal entity registration number and confirm that the stabilised monomer is covered by the registration. In China, the audit checks the hazardous chemical business licence, the safety production licence, and the environmental pollutant discharge permit against the manufacturing site’s actual address. If the sales office and the plant are in different provinces, the permit name must match the loading terminal.

Supply-chain reliability and contingency inventory are checked sixth. The supplier should disclose the propylene and ammonia feedstock contract positions, not pricing. The audit asks whether the plant has direct pipeline supply of propylene or is dependent on trucked propylene during refinery turnarounds. The minimum evidence is a 30-day inventory of merchant acrylonitrile or a named third-party tank farm. The qualification also examines the supplier’s emergency response record: previous spill, fire, or polymerisation incidents, and whether the site can dispatch a technical team to a customer’s tank farm within 48 h. If the supplier’s only asset is a trading licence without a terminal, that operation should not substitute for a primary source.

Audit evidence and management of change are handled as the seventh gate. The supplier must provide ISO 9001:2015 certification with scope covering acrylonitrile manufacturing, ISO 14001:2015 certification, and ISO 45001:2018 certification. The audit should apply ISO 9001:2015 clauses 8.4.1 and 8.4.2 as the minimum control for external providers. It should also review the supplier’s management of change records for the previous 24 months for changes in catalyst vendor, inhibitor vendor, engineering control systems, or recovery solvent. An unreviewed change in inhibitor source can alter colour and polymerisation behaviour even if the nominal MEHQ concentration remains within 35–50 mg/kg.