The role of temperature program and catalytic system on the quality of acrylonitrile-butadiene-styrene degradation oil

Thermal and catalytic degradation of acrylonitrile-butadien-styrene copolymer (ABS) was performed at 450degreesC by semi-batch operation. Four different temperature programs were used for thermal degradation. SA4 silica alumina and three SA4/iron oxide combinations (gamma-Fe2O3, a Fe3O4-C composite and alpha-FeOOH) were used for catalytic degradation. The heating rate affects the quality of the degradation oil, the following heating program giving the lowest amount of heavy nitrogen-containing compounds: room temperature -->400degreesC (heating rate beta = 10degreesC min(-1)) --> 450degreesC (beta = 1degreesC min(-1); then isothermally hold at 450degreesC for 210 min). SA4 catalyst used in liquid phase contact mode has a cracking effect on ABS degradation. The SA4/iron oxide catalytic systems give better results than the separate use of the catalysts, converting the heavy nitrogen (N)-containing compounds into light aliphatic nitrites that can be easily removed from the degradation oil by distillation. With SA4/alpha-FeOOH system the amount of 4-phenylbutyronitrile, the main N-containing compound from ABS thermal degradation, was strongly decreased in oil, from 17.5 to 1.7 wt.%. (C) 2002 Elsevier Science B.V. All rights reserved.