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 450°C by semi-batch operation. Four different temperature programs were used for thermal degradation. SA4 silica alumina and three SA4/iron oxide combinations (γ-Fe₂O₃, a Fe₃O₄-C composite and α-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→400°C (heating rate β = 10°C min^-1)→450°C (β = 1°C min^-1; then isothermally hold at 450°C 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 nitriles that can be easily removed from the degradation oil by distillation. With SA4/α-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.%.