Hg-free electro-thermal cascade catalysis for acetylene upgrading into polyvinyl chloride precursor.

Acetylene hydrochlorination is the predominant route for producing polyvinyl chloride (PVC) precursors in coal-rich, oil-poor regions. However, this conventional thermocatalytic pathway inevitably uses Hg-based catalysts, which pose serious threats to the environment and human health. Here, we propose an alternative cascade conversion strategy that efficiently converts acetylene to pure dichloroethane (PVC precursor) under ambient conditions without using Hg-based catalysts. This strategy couples an electrocatalytic reactor with a thermocatalytic reactor. In the electrocatalytic reactor, highly selective formation of C₂H₄ (FEC₂H₄ = 95%) and Cl₂ (FECl₂= 90%) is achieved at a current density of 1 A·cm⁻², using electrochemically in-situ reconstructed Cu nanoparticles as the cathode and commercial RuO₂-Ti mesh as the anode. By employing two tandem electrolyzers, a C₂H₂ conversion efficiency of 99.6% is obtained. The generated C₂H₄ and Cl₂ gases are then directly fed into a thermocatalytic reactor, where they are upgraded to high-purity dichloroethane with a productivity of 0.653 mmol·cm⁻²·h⁻¹. These results demonstrate a promising strategy to partially replace the acetylene hydrochlorination process, providing an alternative solution for the PVC precursor and ethylene production industries in both oil-rich or coal-rich regions in the future.