HYDROGENATION OF NATURAL-RUBBER USING NICKEL 2-ETHYLHEXANOATE CATALYST IN COMBINATION WITH TRIISOBUTYLALUMINUM

Kinetic studies for the homogeneous hydrogenation of natural rubber, i n the presence of nickel 8-ethylhexanoate and triisobutylaluminum, hav e been carried out by monitoring the change in hydrogen pressure in a Parr reactor of fixed volume. H-1-NMR spectroscopy provides the measur ements of the extent of hydrogenation. The reaction kinetics, in the p resence of a fixed amount of catalyst, showed an overall second-order kinetic with respect to [H-2] and [C=C]. The reaction has a relatively low apparent activation energy of 26.0 kJ mol(-1) and is therefore su itable for the hydrogenation of natural rubber at ambient conditions t o minimize side reactions, The impurities in commercial rubbers have a slight effect on the catalyst activity. (C) 1996 John Wiley & Sons, I nc.