Thermodynamic evaluation using the law of mass action under consideration of the activity coefficients in the system NdCl3-HCl (or NaOH)-H2O-DEHPA-kerosene

For the recovery of neodymium, an important rare earth metal, solvent extraction using DEHPA as extractant is a possible process for winning and recycling. A preceding study by the authors has provided extensive experimental data of the system neodymium-chloride-hydrochloric acid (or sodium hydroxide)-water-di-(2-ethylhexyl)phosphoric acid (DEHPA)-kerosene. It was found that the description of the reaction Nd3++3(DEHPA)2 ⇄ Nd(DEHP‧DEHPA)3+3H+ by an ideal mass action law is only partly satisfactory. This article investigates the contribution of several parameters to non-ideality. On this basis, expressions for activity coefficients of neodymium in the aqueous phase as well as DEHPA and neodymium in the organic phase are derived. The resulting equations are shown to represent the system with considerably better accuracy than previously possible.

The Influence of co-catalyst in the Polymerization of 1,3-butadiene Catalyzed by Neodymium Chloride Tripentanolate

Triisobutylaluminum (TIBA), triethylaluminum (TEA), di-isobutylaluminum hydride (DIBAH) and methylaluminoxane (MAO) were evaluated as activators of neodymium chloride tripentanolate catalyst in order to investigate their influence over the catalytic activi-ty, macro- and microstructure, and thermal properties of of resulting polybutadienes. The higher catalytic activities were achieved by TEA and TIBA as co-catalysts, whereas TIBA and DIBAH led to the poly-mers with highest cis-1,4 structure content with 98.4 and 97.3% re-spectively. The catalytic activity was remarkably poor with MAO as co-catalyst, as well as low stereocontrol. Number average molecular weight values were observed in the range of 260 to 720 kg/mol.