From Mobile Phones to Catalysts: E-Waste-Derived Heterogeneous Copper Catalysts for Hydrogenation Reactions

Electronic waste or E-waste, produced from end-of-life electronic equipment, is the fastest growing solid waste stream, and its rapid generation creates significant environmental problems on a global scale. E-waste contains valuable metals in much higher concentrations than their respective primary resources - metal ores. Currently, less than a quarter of all E-waste is being recycled to recover precious metals; thus, most of the waste is being exported to developing countries, where it is often landfilled and stockpiled. Poor treatment of this hazardous waste causes environmental damage and poses serious health risks to inhabitants in these areas. Therefore, the development of new strategies for the recovery and valorization of metals from E-waste is of increasing importance. In this paper, we describe a methodology for converting E-waste to useful catalytic materials while producing gold-enriched solids as the byproduct. In particular, we report a copper-based heterogeneous catalyst (Cu-iKat) obtained from cellular and mobile phone printed circuit boards (PCBs) via precipitation/deposition of PCB metal leachate on an inert γ-alumina support. This Cu-iKat was characterized by powder X-ray diffraction (XRD), high-resolution X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), and its catalytic activity was demonstrated on hydrogenation of ketones and N-heterocycles. Moreover, Cu-iKat can be used for deoxygenation of benzyl alcohols and hydrogenolysis of formamides to amines and methanol.