Catalytic conversion of tetrabromobisphenol A (TBBPA) by supported transition metal catalysts: Experimental study of reaction paths

• Supported nickel and copper catalysts in decomposition of TBBPA in organic phase. • Ni/Al 2 O 3 exhibited high potential in conversion of TBBPA. • Bromine was detected in the catalysts after the reaction implying catalyst poisoning. • Three reaction routes were proposed based on the analysis of reaction products. Tetrabromobisphenol A (TBBPA) is a widely used brominated flame retardant. It is harmful and persistent in the environment, and therefore the removal of this brominated flame retardant from plastic waste has drawn attention. Catalytic conversion and debromination of TBBPA offer a viable method for reducing the amount of harmful substances entering plastic recycling processes. In this work, different transition metal catalysts were studied, and their activity was evaluated for decomposition and debromination of TBBPA. The catalytic reactions were conducted in a batch-type autoclave reactor under reductive conditions. Ni/Al 2 O 3 catalysts resulted in the highest conversions, but Ni/TiO 2 catalysts produced more completely debrominated products, despite the catalyst being poisoned by bromine. In reactions involving alumina, the support likely acted as a halogen sink, protecting the nickel from direct deactivation. Gas chromatography-mass spectrometry (GC–MS) analysis of the reaction products suggested a possible scheme for TBBPA debromination and decomposition pathways. The main reaction paths for TBBPA debromination involved either step-by-step debromination or the debromination of compounds formed after TBBPA decomposed into two monophenol products. A notable amount of benzyl toluene was produced as a side reaction product from the toluene solvent. Overall, the results indicated that Ni/Al 2 O 3 catalysts offer a promising option for the effective decomposition of TBBPA.