Measurement of cloud points for the systems polybutadiene + propane and polybutadiene + diethyl ether at high pressure

JUAN MANUEL MILANESIO; GUILLERMO DOMINGO MABE; ANDRES CIOLINO; LIDIA MARÍA QUINZANI; MARCELO SANTIAGO ZABALOY

Algarve, Praia da Rocha, Portugal

Conferencia; VIII Iberoamerican Conference on Phase Equilibria and Fluid Properties for Process Design (EQUIFASE 2009); 2009

Laboratory of Separation and Reaction Engineering/ Laboratory of Catalysis and Materials – Faculdade de Engenharia da Universidade do Porto.

In the conventional hydrogenation of heavy compounds, like polymers, the immiscibility in thebinary subsystem hydrogen–heavy substrate cannot be overcome by adding a solvent. Onthe other hand, by using a supercritical or quasicritical solvent, we can have the hydrogenand the polymer dissolved in a single phase. This implies higher mass transfer rates. Toselect the operating conditions of a supercritical reactor, it is convenient to determine thephase boundaries of the subsystems solvent-hydrogen and solvent-polymer. In this work,we obtained experimental cloud points for binary systems made of polybutadiene (PB) and asolvent (propane or diethyl ether). The present results partially correspond to a phaseequilibrium engineering study in which we determined the single-phase boundary for Solvent+ PB systems. The final aim is to hydrogenate PBs using supercritical or quasicritical fluidsas reaction media.A high pressure variable-volume phase-equilibrium cell has been designed and built. The cellhas a glass window, a movable piston and a magnetic stirring system. We used thisapparatus to measure cloud-point (liquid-liquid) pressures for the systems PB + propane andPB + diethyl ether (DEE). The temperature range was from 316 K to 457 K. The maximumpressure was 558 bar. The PBs used in this study have very narrow molecular weightdistributions. The polymer number-averaged molecular weight was 14000 g/mol for the PB +propane experiments and 40000 g/mol for the PB-DEE data. The PBs were obtained usinganionic polymerization techniques