Diluent increasing organic concentration

The effect of increasing TBP concentration in the organic phase results in an increase in its solubility in water. Furthermore, the diluent used also affects the TBP solubility. 

T5q)ical reaction conditions are 90- 110°C and 3-4.5 MPa. The diluent used is normally isobutane, which facilitates the separation by vaporisation in a low pressure flash tank and permits higher operating temperatures than longer chained organic solvents. After treatment in purification beds to remove catalyst poisons, the ethylene monomer, comonomer and recycled diluent are fed to the loop reactor. The catalyst is flushed out of the feed container into the loop reactor by the diluent. The polymer concentration in the reactor slurry may range from 30 to 50 wt-%. The slurry from the reactor is passed through a sedimentation zone, where the polymer concentration increases up to 55 - 65 wt-%, and the slurry is then fed to the flash tank, where the hydrocarbons evaporate at a low pressure of about 0.15 MPa. 

The nergistic effect was found to be dependent on the diluent. It is pronoimced with a mixed dodecane/xylene diluent, and is weak with mixed heptane/xylene, hex-ane/xylene, and pure xylene diluents. The organic phase was found to eontain simultaneously two or three synergistie complexes, with the compositions (A+)(Ln(N03)4-2B ), (A )(Ln(N03)4 3B ), and (A )2(ln(N03)5-B ), where Ln is a lanthanide (HI), A is a trioctylmethylammonium cation and B is a tributyl phosphate molecule. The synergistie complex stability was found to decrease with inerease in atomie number. Increasing the tributyl phosphate concentration gradually suppressed the separation factors for Pr-Nd and Eu-Gd pairs. 

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