Process description of TBP Synthesis

    Basic Principle:

    The TBP Plant at HWP-Talcher is intended for production of high quality Tri-Butyl Phosphate (TBP). The plant operation is carried out in batches. The capacity of the plant is 60 MTPA. The annual capacity is based on 300 operating days and batch capacity of about 400 KGs in two days of operation.

    The production of TBP involves mainly four steps as given below :

    • Esterification reaction between phosphorous oxy-chloride (POCl3) and n-Butanol to produce Tri-Butyl Phosphate.
      Raw Materials used:
      • Phosphorous oxy-chloride ( POCl3 )
      • n-Butanol (C4H9OH )
      Reactions involved:

      POCl3 + 3 C4H9OH PO (C4H9O) 3 + 3HCl

    • Neutralization of some undesired acidic compounds, like HCl and mono & dibutyl phosphoric acids.
      Raw Materials used:
      • Digested charge from reaction step 1.
      • Sodium Carbonate (Na2CO3) Solution
      Reaction involved:

      2HCl + Na2CO3 -> 2NaCl + H2O + CO2

      PO(OC4H9) Cl2 + 2 Na2CO3 -> PO (OC4H9) (ONa) 2 + 2NaCl + 2 CO2 }Reaction with traces

      PO (OC4H9)2 Cl + Na2CO3 -> PO (OC4H9) 2 (ONa) + NaCl + CO2 } of impurities

    • Butanol Recovery:

      The washed organic phase contains crude product and excess amount of n-Butanol. This is taken to separate reactor to recover the excess n-butanol, because the economy of the process depends greatly on the recovery and reuse of n-butanol(minimal loss).

    • Final Purification of crude TBP:

      The crude product contains TBP, residual amount of n-butanol, mono-phosphoric acid, di-phosphoric acid, water and other impurities formed during the process. These impurities have to be removed in order to get a product of high purity to meet the stringent requirement of nuclear industry. The Final purification of crude TBP is carried out by batch distillation under vacuum in two stages. n-butanol and water contents of crude TBP are first removed by carrying out distillation under low vacuum. Butanol and water removed is then sent to n-butanol purification unit to recover pure butanol for reuse. After removal of Butanol and water, product TBP is transferred to product tank.

    Last updated on: 04-Feb-2019