Purified Terephthalic Acid
The para-aromatic dicarboxylic acid supplied by Chelora Chemicals — the primary raw material for PET polyester fibre, bottle resin and packaging film — exported from Indonesia as white crystalline powder with full batch documentation on every shipment.
What Purified Terephthalic Acid is, and why buyers source it
A working overview of the compound's chemistry, its position as the dominant raw material for modern PET manufacture, and the grade Chelora Chemicals keeps in regular supply.
Purified Terephthalic Acid is the para-isomer of benzenedicarboxylic acid: a benzene ring carrying two carboxylic acid groups directly opposite one another. That symmetric, linear arrangement is central to its commercial value — when esterified with a glycol, the two acid groups extend the chain in a straight line on either side of the rigid aromatic ring, which is exactly the structural motif that gives PET polyester its strength, clarity and processability.
At room temperature it is a white, odourless crystalline powder that is practically insoluble in cold water and sublimes rather than melting cleanly at atmospheric pressure, reflecting the strong hydrogen-bonded crystal lattice its two carboxylic acid groups form. It is the dominant raw material for PET manufacture today, having progressively displaced the older dimethyl terephthalate route as PTA purification technology matured.
Where it fits in the value chain
Purified Terephthalic Acid's overwhelming end use is direct esterification with monoethylene glycol (and, for certain grades, a small proportion of diethylene glycol or other glycol modifiers) to produce polyethylene terephthalate (PET), the polyester resin spun into textile and industrial filament yarn, blow-moulded into beverage bottles and packaging containers, and extruded into film. A smaller but established use is esterification with 1,4-butanediol to give polybutylene terephthalate (PBT), an engineering thermoplastic used in electrical and automotive components, and with other diols to give specialty polyester resins.
Grade we supply
Chelora Chemicals offers Purified Terephthalic Acid in fibre/resin grade (99.9%+ purity), suited to direct esterification for PET fibre, bottle-resin and film manufacture, and PBT production. The grade is supplied with a batch-wise certificate of analysis.
How Purified Terephthalic Acid is made
An overview of the production route for orientation purposes. Our manufacturing partners' own process parameters and in-process controls are proprietary and are not disclosed beyond what is needed to interpret the certificate of analysis.
Purified Terephthalic Acid is manufactured by the catalytic liquid-phase oxidation of para-xylene with air, carried out in acetic acid solvent using a cobalt-manganese-bromide catalyst system at elevated temperature and pressure (the process widely known by its originating developer's name, the Amoco/MC process). Both methyl groups on the para-xylene ring are oxidised through to carboxylic acid groups, giving crude terephthalic acid, which also contains a troublesome impurity, 4-carboxybenzaldehyde (4-CBA), formed when oxidation of one methyl group stops at the aldehyde stage.
Because 4-CBA disrupts polyester chain growth and discolours the finished polymer if carried through, the crude acid is purified in a dedicated step: it is dissolved in water under pressure at high temperature and passed over a palladium catalyst, which selectively hydrogenates the 4-CBA to p-toluic acid, a far more soluble by-product that is then separated from the terephthalic acid by crystallisation. This hydrogenation-purification step, together with recrystallisation, is what distinguishes purified terephthalic acid (PTA) from the cruder, directly-oxidised material, and is what makes PTA suitable for direct esterification with glycol without the intermediate methyl-ester step the older DMT route required.
Industries and processes that use it
Purified Terephthalic Acid is consumed overwhelmingly by PET polyester manufacture, with established secondary demand from PBT and specialty polyester resins. The fields below account for most of the demand we see through our export desk.
PET Fibre & Filament Yarn
Esterified with monoethylene glycol to produce PET resin, spun into textile staple fibre and industrial filament yarn.
PET Bottle & Packaging Resin
The dominant raw material for bottle-grade PET resin, blow-moulded into beverage bottles and rigid packaging containers.
PET Film
Esterified and polymerised into film-grade PET, biaxially oriented for packaging, electrical insulation and industrial film applications.
PBT & Specialty Polyester Resins
Esterified with 1,4-butanediol or other diols to give polybutylene terephthalate and other engineering or specialty polyester resins.
How the molecule is typically carried forward
The two symmetric carboxylic acid groups on the rigid aromatic ring govern almost all of this molecule's further reaction chemistry. Reaction classes below account for most of the ways Purified Terephthalic Acid is converted into a finished polyester.
Direct Esterification
Each carboxylic acid reacts directly with a glycol hydroxyl, releasing water, to form an ester linkage — the first step of modern PET and PBT manufacture.
Polycondensation
The resulting bis(glycol ester) is further polymerised under vacuum and heat, releasing excess glycol and building the long PET or PBT polymer chain.
Transesterification (via the DMT Route)
Where the ester-route feedstock dimethyl terephthalate is used instead of PTA directly, the methyl esters undergo transesterification with glycol, releasing methanol rather than water.
Solid-State Polymerisation
For high-molecular-weight bottle-grade resin, the initial melt-phase polymer is further polymerised in the solid state at elevated temperature under vacuum or inert gas, building molecular weight beyond what melt-phase processing alone achieves.
Purified Terephthalic Acid against other polyester intermediates we supply
Buyers sourcing PTA for polyester manufacture often also consider the alternative ester-route feedstock, or the nylon-chain intermediates for comparison. A quick reference to what else is on our regular supply list.
| Product | CAS Number | Category | Notes |
|---|---|---|---|
| Purified Terephthalic Acid | 100-21-0 | Aromatic dicarboxylic acid | The product on this page — the dominant raw material for modern PET manufacture. |
| Dimethyl Terephthalate | 120-61-6 | Aromatic diester | The ester-route alternative raw material for PET and specialty polyester resins — see its product page. |
| Adipic Acid | 124-04-9 | Aliphatic dicarboxylic acid | A related dicarboxylic acid, the co-monomer of nylon 66 — see its product page. |
| Caprolactam | 105-60-2 | Cyclic lactam | The single-monomer feedstock for nylon 6, a related condensation-polymer chain — see its product page. |
Exact physical constants and purity specifications are confirmed per batch on the certificate of analysis — treat the notes above as a sourcing guide, not a specification sheet, for products other than Purified Terephthalic Acid.
Safety classification at a glance
Based on GHS classification as commonly listed for this substance. This is a summary for orientation only — always work from the current safety data sheet supplied with your specific batch.
Causes serious eye irritation.
May cause respiratory irritation.
Can form combustible dust clouds under specific conditions; dust-explosion precautions apply in bulk handling.
Comparatively low acute oral and dermal toxicity relative to many industrial organic acids.
Handled as fine crystalline powder; minimise airborne dust during transfer and packing.
Safety goggles and dust-suitable respiratory protection are the baseline for routine handling.
Practically insoluble in water; spills are managed as a solid rather than a liquid hazard.
Warning — GHS07 harmful pictogram applies.
This compound causes serious eye irritation and may cause respiratory irritation when handled as fine dust, and can form a combustible dust cloud under specific conditions typical of bulk powder handling. It should be handled with eye protection, dust control and standard combustible-dust precautions (bonding/grounding of handling equipment, avoidance of ignition sources) during milling, conveying and packing. Full first-aid, storage, spill and PPE guidance is in the MSDS issued with every shipment, and should be read in full before this material is handled.
Keeping it on spec between delivery and use
General storage guidance for this grade. Site-specific storage rules, segregation requirements and re-test intervals should follow your own EHS procedures and the MSDS issued with your batch.
Store in a cool, dry area, in tightly closed original packaging or a dedicated silo, protected from moisture, which can affect flow and dosing characteristics. Bulk storage and handling systems should follow standard combustible-dust precautions, including bonding/grounding and dust-collection equipment. Re-check assay, 4-CBA content and colour on a batch held past its retest date before use.
How it ships from Indonesia
Standard packing and export terms for this product. Confirm exact figures against your order — they vary slightly by destination and quantity.
What travels with every batch
Specification is agreed before the purchase order, not discovered on arrival. Every shipment of Purified Terephthalic Acid leaves with a documented, checkable paper trail.
Certificate of Analysis
Batch-wise assay, colour and key physical constants, issued against the agreed specification so your QC team can check it, not just file it.
Safety Data Sheet
GHS-format SDS in English covering hazard classification, handling, storage, first-aid and spill response for the exact grade shipped.
Technical Data Sheet
Reference physical and chemical properties, recommended storage and typical applications, for internal circulation to your process or R&D teams.
Certificate of Origin
Confirms Indonesian origin for customs clearance and any preferential-duty claim at your destination port.
Dangerous Goods Declaration
UN packing group, classification and shipper's declaration prepared ahead of loading so documentation never holds up customs.
Third-Party Inspection
Independent pre-shipment inspection and re-sampling can be arranged on request, at your cost, for buyers who require it as a matter of policy.
Frequently asked questions
What buyers most often ask our sales desk about this grade.
01What is Purified Terephthalic Acid used for?+
02What is the CAS number of Purified Terephthalic Acid?+
03How is Purified Terephthalic Acid made?+
04What purity grade does Chelora Chemicals supply?+
05Is Purified Terephthalic Acid hazardous?+
06Why did PTA replace DMT as the dominant PET raw material?+
07What packing options are available?+
08How long does delivery take?+
09Can I get a sample before placing a bulk order?+
10Do you supply the ester-route alternative as well?+
Need Purified Terephthalic Acid on spec, on time?
Send us your required purity, quantity, packing preference and destination port. Our desk quotes most enquiries within one working day.