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

JUAN M. MILANESIO; GUILLERMO MABE; ANDRES CIOLINO; LIDIA MARÍA QUINZANI; MARCELO S. ZABALOY

Porto

Congreso; VIII Iberoamerican Conference on Phase Equilibria and Fluid Properties for Process Design (EQUIFASE'09); 2009

Universidad de Porto

In the conventional hydrogenation of heavy compounds, like polymers, the immiscibility in the binary subsystem hydrogen–heavy substrate cannot be overcome by adding a solvent. On the other hand, by using a supercritical or quasicritical solvent, we can have the hydrogen and the polymer dissolved in a single phase. This implies higher mass transfer rates.  To select the operating conditions of a supercritical reactor, it is convenient to determine the phase boundaries of the subsystems solvent-hydrogen and solvent-polymer [1]. In this work, we obtained experimental cloud points for binary systems made of polybutadiene and a solvent (propane or diethyl ether). The present results correspond to a phase equilibrium engineering preliminary study in which we determined the single-phase boundary for Solvent + Polybutadiene systems. The final aim is to hydrogenate polybutadienes using supercritical or quasicritical fluids as reaction media. A high pressure variable-volume phase-equilibrium cell has been designed and built. The cell has a glass window, a movable piston and a magnetic stirring system. We used this apparatus to measure cloud point (liquid-liquid) pressures for the systems polybutadiene + propane and polybutadiene + diethyl ether. The temperature range was from 298 K to 498 K. The maximum pressure was 600 bar. The polybutadienes used in this study have very narrow molecular weight distributions. The range for the polymer weight average molar mass was from 15,000 to 50,000 g/mol. The polybutadienes were obtained using anionic polymerization techniques.