Terephthalic Acid

Molecular Structure

Molecular Details

Molecular Formula	C₆H₄(COOH)₂
Molecular Weight	166.13 g/mol
State	Solid at standard conditions

Olefinverbund Integration

Chemistry & Engineering

Reaction Equation	p-Xylene + O₂ → PTA
Thermodynamics	Exothermic oxidation
Catalyst System	Cobalt-Manganese-Bromide (Co-Mn-Br)
Reactor Class	Titanium-lined stirred tank (corrosive + high T/P)
Process Considerations	Crude TA must be hydrogenated to remove colored impurities (4-CBA) for bottle grade.

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

Applications

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

Reaction Diagram

Overall Reaction: C8H10 + 3O2 -> C8H6O4 + 2H2O

Unit Operations

Process steps following chemical engineering unit operation principles:

Step	Operation	Description
1	p-Xylene Oxidation	Air oxidation in acetic acid at 175-225°C
2	Co-Mn-Br Catalysis	Homogeneous catalyst system
3	Crystallization	Crystallize crude TPA from mother liquor
4	Hydrogenation	Purify by catalytic hydrogenation (PTA process)
5	Filtration	Filter and wash purified crystals
6	Drying	Dry to specification moisture content

S88 Batch Control Model

This module follows the ISA-88 (S88) batch control standard. Below is a simplified BatchML schema 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>

**Key S88 Concepts:**
- **Process Cell**: The physical grouping containing all equipment for this process
- **Unit**: The major equipment that performs the synthesis
- **Equipment Modules**: Individual pieces of equipment (reactors, columns, etc.)
- **Unit Procedure**: The sequence of operations to produce the product
- **Phases**: The lowest level of procedural control (e.g., REACT, SEPARATE, PURIFY)

Key S88 Concepts:
• Process Cell: Physical grouping containing all equipment
• Unit: Major equipment performing synthesis
• Equipment Modules: Individual pieces (reactors, columns, etc.)
• Phases: Lowest level of procedural control (REACT, SEPARATE, etc.)

---

This Synthesis Module is part of the 100chemicals Olefinverbund — an integrated chemical production network designed for extraterrestrial civilization on Moon and Mars.