Removal of nitrogen, bromine, and chlorine from PP/PE/PS/PVC/ABS-Br pyrolysis liquid products using Fe- and Ca-based catalysts

The thermal and catalytic degradation of a complex polymer mixture was performed at 450 °C at atmospheric pressure in a batch process. The mixture contained polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylonitrile-butadiene-styrene copolymer with a brominated flame retardant and antimony oxide synergist (ABS-Br) and poly(vinyl chloride) (PVC), in a 3/3/2/1/1 weight ratio. The effect of iron (FeOOH and Fe-C composite) and calcium (CaCO3 and Ca-C composite) based catalysts for removal of heteroatom- (nitrogen, bromine, and chlorine) containing compounds in oil products was studied. Changes in the amount and distribution of heteroatoms were described using NP gram curves. Iron catalysts give best results for bromine removal from decomposition oil while calcium catalysts have high efficiency for chlorine removal; however, both Fe- and Ca-catalysts have low effect in nitrogen removal. Carbon composite catalysts give three times less chlorine but they produce higher amounts of nitrogen in degradation oils than the corresponding Fe and Ca pure compounds. In bromine removal Ca-C composite shows higher effect compared to CaCO3 while Fe-C composite has slightly worse effect than FeOOH.