Electrochemical CaC2 -Mediated Conversion of Biochar to C2 H2 : High Carbon Efficiency and Low Contamination.

Abstract

The carbon to CaC2 route is promising to provide a sustainable elementary unit, C2 H2 , for the organic synthesis industry, but the traditional thermal reaction process suffers from low carbon efficiency, harmful gas contamination, high temperature operation, and risky CO management. We herein report a high carbon efficiency (ca. 100 %) conversion of biochar to C2 H2 through an electrolytic synthesis of solid CaC2 in molten CaCl2 /KCl/CaO at 973 K. The main reactions are carbon reduction to CaC2 at the solid carbon cathode and oxygen evolution at an inert anode. Meanwhile, the electrolysis removes S and P from the solid cathode, avoiding the formation of CaS and Ca3 P2 in CaC2 and consequently eliminating H2 S and PH3 contamination in the finally produced C2 H2 .