Using red phosphorus, a series of unsupported nanosized transition-metal phosphides (NiP, MoP, and FeP) were synthesized in situ in the presence of the brominated flame retardant tetrabromobisphenol A (TBBPA). Their catalytic activity was evaluated in the hydroprocessing of model polymer waste mixtures (polystyrene, polyethylene, polypropylene, and polyvinyl chloride) containing 10 wt % TBBPA. Reactions were conducted at 320–380°C, 6 MPa H2, with a metal-to-polymer weight ratio of 1 : 80 for 7 h. A comparative investigation of the three phosphides in the hydroprocessing of the polyethylene, polypropylene, and polystyrene mixtures with 10 wt % TBBPA demonstrates that at 320°C, NiP minimized the formation of organobromine intermediates such as 1-(1-methylethylene)-3,5-dibromo-4-hydroxybenzene (6 wt %) and 2,6-dibromophenol (4 wt %), achieving superior debrominating activity. Raising the temperature to 380°C enhanced debromination for all catalysts but reduced styrene selectivity due to aromatic hydrogenation. The optimal temperature for styrene yield was 340°C. Catalyst reuse led to gradual deactivation via the formation of metal bromides and agglomeration of catalyst particles, highlighting the need for effective regeneration methods.
Dzhabarov et al. (2026) studied this question.