Free radicals induced ultra-rapid synthesis of N-doped carbon sphere catalyst with boosted pyrrolic N active sites for efficient acetylene hydrochlorination

Activated carbon-supported HgCl2 catalysts have seriously impeded the development of the polyvinyl chloride(PVC)industry due to the sublimation of Hg species and environmental pollution problems.Herein,the template-free and organic solvent-free strategy was devised to synthesize non-metallic based nitrogen-doped carbon(U-NC)sphere catalyst for acetylene hydrochlorination.This green strategy via ultrasonic chemistry initiates resin crosslinking reactions between aminophenol and formaldehyde resin by free radicals,leading to the ultra-rapid formation of U-NC with remarkably high pyrrolic N content in only 5 min.This U-NC catalyst exhibited an outstanding space-time-yield(1.6 gVCM·gcat^(−1)·h^(−1)),even comparable to the reported metallic catalyst.By combining kinetic analysis,advanced characterizations,density functional theory,it is found that the amount of pyrrolic N is in linear with C_(2)H_(2)conversion,pyrrolic N in U-NC can effectively improve acetylene hydrochlorination performance by mediating HCl adsorption.This work sheds new light on rationally constructing metal-free catalyst for acetylene hydrochlorination.