Terephthalic Acid

C₆H₄(COOH)₂  ·  166.13 g/mol

C₆H₄(COOH)₂

Key monomer for PET polyester fibers and bottles

Molecular Weight
166.13 g/mol
State
Solid
Catalyst
Cobalt-Manganese-Bromide
Reactor
Titanium-lined stirred t
Terephthalic Acid molecular structure
2D structure

Olefinverbund Integration

Inputs
Xylene, Acetic Acid, **Oxygen** (Feedstock)
Product
Terephthalic Acid

Chemistry & Engineering

Reactionp-Xylene + O₂ → PTA
ThermodynamicsExothermic oxidation
CatalystCobalt-Manganese-Bromide (Co-Mn-Br)
Reactor classTitanium-lined stirred tank (corrosive + high T/P)
NoteCrude TA must be hydrogenated to remove colored impurities (4-CBA) for bottle grade.

Applications

  • PET fiber and film production
  • PET bottle resin
  • Polybutylene terephthalate (PBT)
  • Unsaturated polyester resins

Extraterrestrial Production Pattern

  1. p-Xylene oxidation with air
  2. Co-Mn-Br catalyst in acetic acid solvent
  3. Operating at 175-225°C and 15-30 bar
  4. Crystallization and hydrogenation purification

Reaction Diagram

C8H10 + 3O2 -> C8H6O4 + 2H2O

Unit Operations

Process steps following chemical engineering unit operation principles

#OperationDescription
1p-Xylene OxidationAir oxidation in acetic acid at 175-225°C
2Co-Mn-Br CatalysisHomogeneous catalyst system
3CrystallizationCrystallize crude TPA from mother liquor
4HydrogenationPurify by catalytic hydrogenation (PTA process)
5FiltrationFilter and wash purified crystals
6DryingDry to specification moisture content

S88 Batch Control Model

ISA-88 BatchML schema — simplified for educational purposes

<?xml version="1.0" encoding="UTF-8"?>
<!-- ISA-88 Batch Control Model for Terephthalic Acid -->
<!-- Educational schema - simplified for demonstration -->
<BatchML xmlns="http://www.wbf.org/xml/B2MML-V0600">
  
  <ProcessCell ID="PTA_PLANT_CELL">
    <Description>Process cell for Terephthalic Acid production</Description>
    
    <Unit ID="PTA_PLANT">
      <Description>Main synthesis unit</Description>
      
      <!-- Equipment Modules -->
      <EquipmentModule ID="OXIDATION_REACTOR">
        <Description>Oxidation Reactor</Description>
      </EquipmentModule>
      <EquipmentModule ID="CATALYST_SYSTEM">
        <Description>Catalyst System</Description>
      </EquipmentModule>
      <EquipmentModule ID="CRYSTALLIZER">
        <Description>Crystallizer</Description>
      </EquipmentModule>
      <EquipmentModule ID="HYDROGENATOR">
        <Description>Hydrogenator</Description>
      </EquipmentModule>
      <EquipmentModule ID="FILTER">
        <Description>Filter</Description>
      </EquipmentModule>
      <EquipmentModule ID="DRYER">
        <Description>Dryer</Description>
      </EquipmentModule>
    </Unit>
  </ProcessCell>
  
  <MasterRecipe ID="PTA_PLANT_RECIPE">
    <Description>Master recipe for Terephthalic Acid</Description>
    <ProductID>TEREPHTHALIC_ACID</ProductID>
    
    <UnitProcedure ID="PTA_PLANT_UP">
      <Description>Unit procedure for synthesis</Description>
      
      <Operation ID="OP_01">
        <Description>Operation 1</Description>
        <Phase ID="OXIDIZE">
          <Description>Oxidize phase</Description>
          <PhaseLogic>
            <Step ID="STEP_1"><Action>Initialize</Action></Step>
            <Step ID="STEP_2"><Action>Execute</Action></Step>
            <Step ID="STEP_3"><Action>Complete</Action></Step>
          </PhaseLogic>
        </Phase>
      </Operation>
      
      <Operation ID="OP_02">
        <Description>Operation 2</Description>
        <Phase ID="CATALYZE">
          <Description>Catalyze phase</Description>
          <PhaseLogic>
            <Step ID="STEP_1"><Action>Initialize</Action></Step>
            <Step ID="STEP_2"><Action>Execute</Action></Step>
            <Step ID="STEP_3"><Action>Complete</Action></Step>
          </PhaseLogic>
        </Phase>
      </Operation>
      
      <Operation ID="OP_03">
        <Description>Operation 3</Description>
        <Phase ID="CRYSTALLIZE">
          <Description>Crystallize phase</Description>
          <PhaseLogic>
            <Step ID="STEP_1"><Action>Initialize</Action></Step>
            <Step ID="STEP_2"><Action>Execute</Action></Step>
            <Step ID="STEP_3"><Action>Complete</Action></Step>
          </PhaseLogic>
        </Phase>
      </Operation>
      
      <Operation ID="OP_04">
        <Description>Operation 4</Description>
        <Phase ID="HYDROGENATE">
          <Description>Hydrogenate phase</Description>
          <PhaseLogic>
            <Step ID="STEP_1"><Action>Initialize</Action></Step>
            <Step ID="STEP_2"><Action>Execute</Action></Step>
            <Step ID="STEP_3"><Action>Complete</Action></Step>
          </PhaseLogic>
        </Phase>
      </Operation>
      
      <Operation ID="OP_05">
        <Description>Operation 5</Description>
        <Phase ID="FILTER">
          <Description>Filter phase</Description>
          <PhaseLogic>
            <Step ID="STEP_1"><Action>Initialize</Action></Step>
            <Step ID="STEP_2"><Action>Execute</Action></Step>
            <Step ID="STEP_3"><Action>Complete</Action></Step>
          </PhaseLogic>
        </Phase>
      </Operation>
      
      <Operation ID="OP_06">
        <Description>Operation 6</Description>
        <Phase ID="DRY">
          <Description>Dry phase</Description>
          <PhaseLogic>
            <Step ID="STEP_1"><Action>Initialize</Action></Step>
            <Step ID="STEP_2"><Action>Execute</Action></Step>
            <Step ID="STEP_3"><Action>Complete</Action></Step>
          </PhaseLogic>
        </Phase>
      </Operation>
    </UnitProcedure>
  </MasterRecipe>
  
</BatchML>
Process CellPhysical grouping of all production equipment
UnitMajor equipment performing the synthesis
Equipment ModulesIndividual devices: reactors, columns, absorbers
PhasesLowest control level: REACT, SEPARATE, PURIFY

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