Phthalic Anhydride

Molecular Structure

Molecular Details

Molecular Formula	C₆H₄(CO)₂O
Molecular Weight	148.12 g/mol
State	Solid at standard conditions

Olefinverbund Integration

Chemistry & Engineering

Reaction Equation	o-Xylene + 3O₂ → Phthalic Anhydride + 3H₂O
Thermodynamics	Highly exothermic
Catalyst System	Vanadium Pentoxide on Titania
Reactor Class	Multitubular fixed bed molten salt cooled
Process Considerations	Switchable with Naphthalene feedstock.

Extraterrestrial Production Pattern

1. o-Xylene + O₂ → phthalic anhydride (V₂O₅/TiO₂ catalyst)
2. Fixed-bed reactor at 360-400°C
3. Sublimation and condensation for recovery
4. Alternative: naphthalene oxidation

Applications

• Phthalate plasticizers (DOP, DBP)
• Alkyd resins for paints
• Unsaturated polyester resins
• Dyes and pigments

Reaction Diagram

Overall Reaction: C8H10 + 3O2 -> C8H4O3 + 3H2O (or naphthalene oxidation)

Unit Operations

Process steps following chemical engineering unit operation principles:

Step	Operation	Description
1	o-Xylene Feed	Vaporize and mix with air
2	Oxidation	V₂O₅/TiO₂ catalyst at 340-400°C
3	Switch Condensers	Desublime crude PA on switch condenser tubes
4	Melting	Melt crude PA from condensers
5	Thermal Treatment	Heat to decompose maleic anhydride
6	Distillation	Vacuum distillation to >99.5% PA

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 Phthalic Anhydride -->
<!-- Educational schema - simplified for demonstration -->
<BatchML xmlns="http://www.wbf.org/xml/B2MML-V0600">
  
  <ProcessCell ID="PA_PLANT_CELL">
    <Description>Process cell for Phthalic Anhydride production</Description>
    
    <Unit ID="PA_PLANT">
      <Description>Main synthesis unit</Description>
      
      <!-- Equipment Modules -->
      <EquipmentModule ID="VAPORIZER">
        <Description>Vaporizer</Description>
      </EquipmentModule>
      <EquipmentModule ID="REACTOR">
        <Description>Reactor</Description>
      </EquipmentModule>
      <EquipmentModule ID="SWITCH_CONDENSER">
        <Description>Switch Condenser</Description>
      </EquipmentModule>
      <EquipmentModule ID="MELTER">
        <Description>Melter</Description>
      </EquipmentModule>
      <EquipmentModule ID="TREATMENT">
        <Description>Treatment</Description>
      </EquipmentModule>
      <EquipmentModule ID="COLUMN">
        <Description>Column</Description>
      </EquipmentModule>
    </Unit>
  </ProcessCell>
  
  <MasterRecipe ID="PA_PLANT_RECIPE">
    <Description>Master recipe for Phthalic Anhydride</Description>
    <ProductID>PHTHALIC_ANHYDRIDE</ProductID>
    
    <UnitProcedure ID="PA_PLANT_UP">
      <Description>Unit procedure for synthesis</Description>
      
      <Operation ID="OP_01">
        <Description>Operation 1</Description>
        <Phase ID="VAPORIZE">
          <Description>Vaporize 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="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_03">
        <Description>Operation 3</Description>
        <Phase ID="CONDENSE">
          <Description>Condense 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="MELT">
          <Description>Melt 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="TREAT">
          <Description>Treat 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="DISTILL">
          <Description>Distill 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.