Synthesis and catalytic performance of cesium and potassium salts of aluminum substituted tungstoborate for pyrolysis of polyethylene waste to petrochemical feedstock

Polyoxometalates have gained considerable attention as a catalyst. Herein, we are reporting tungstoborate based catalysts for the conversion of waste polyethylene to liquid fuel. Novel cesium and potassium salts of aluminum substituted tungstoborate Keggin compounds were synthesized by a simple one-pot method and successfully characterized by FTIR, SEM-EDX, thermal analysis, NMR and single-crystal XRD. Catalytic cracking of waste polyethylene by using our prepared aluminum substituted catalysts showed 97% polymer conversion producing 80 wt% of liquid hydrocarbons with a negligible amount of solid residue (similar to 3 wt%), significantly lower compared to thermal cracking where 22 wt% residue was produced. The oil collected at optimum reaction conditions (0.05 catalyst/polymer ratio and 3 h reaction time) was subjected to GC-MS analysis. The results showed that oil produced in catalytic cracking has a high selectivity to gasoline range hydrocarbons while thermal cracking showed selectivity to higher hydrocarbons (C-13-C-26). Olefin selectivity was also more prominent in catalytic cracking. Hence cesium and potassium salts of aluminum substituted tungstoborate are excellent catalysts for acid-catalyzed polymer cracking reactions to produce value-added petrochemicals.