Membrane-Free Electrocatalytic Co-Conversions of PBS Waste Plastics and Maleic Acid into High-PuritySuccinic Acid Solid.

Abstract

Plastic pollution, an increasingly serious global problem, can be addressed through the full lifecycle management of plastics, including plastics recycling as one of the most promising approaches. System design, catalyst development, and product separation are the keys in improving the economics of electrocatalytic plastics recycling. Here, a membrane-free co-production system was devised to produce succinic acid (SA) at both anode and cathode respectively by the co-electrolysis of polybutylene succinate (PBS) waste plastics and biomass-derived maleic acid (MA) for the first time. To this end, Cr3+-Ni(OH)2 electrocatalyst featuring much enhanced 1,4-butanediol (BDO) oxidation reaction (BOR) activity has been synthesized and the role of doped Cr has been revealed as an "electron puller" to accelerate the rate-determining step (RDS) in the Ni2+/Ni3+ cycling. Impressively, an extra-high SA production rate of 3.02 g h-1 and ultra-high apparent Faraday efficiency towards SA (FEapparent=181.5%) have been obtained. A carbon dioxide-assisted sequential precipitation approach has been developed to produce high-purity SA and byproduct NaHCO3 solids. Preliminary techno-economic analysis demonstrates that the reported system is economically profitable and promising for future industrial applications.