A “green” technique for high performance elastomers – fundamental investigation for hydrogenation of nitrile butadiene rubber in supercritical carbon dioxide

Abstract

NBR hydrogenation, catalyzed by OsHCl(CO)(O2)(PCy3)2 is investigated in supercritical carbon dioxide (SC-CO2). The experiments were carried out in a volume-changeable SFT Phase Monitor with a view window. It was found that the catalyst could maintain steady activity in SC-CO2 for a long time and no deactivation or decomposition of the catalyst was observed during the experimental operation periods. The reaction reached a conversion of 98% within 2.5 hours at 150°C. Increasing the temperature, specific area of NBR, CO2 density and catalyst concentration favours higher hydrogenation degree, but the effect of hydrogen pressure is complicated and attention must be given to find the optimal hydrogen pressure. The results suggest that NBR hydrogenation could be possibly realized in SCFs in place of conventional organic solvents.