High Yield of CO and Synchronous S Recovery from the Conversion of CO 2 and H 2 S in Natural Gas Based on a Novel Electrochemical Reactor.

H ₂ S and CO ₂ are the main impurities in raw natural gas, which needs to be purified before use. However, the comprehensive utilization of H ₂ S and CO ₂ has been ignored. Herein, we proposed a fully resource-based method to convert toxic gas H ₂ S and greenhouse gas CO ₂ synchronously into CO and elemental S by using a novel electrochemical reactor. The special designs include that, in the anodic chamber, H ₂ S was oxidized rapidly to S based on the I ^- /I ₃ ^- cyclic redox system to avoid anode passivation. On the other hand, in the cathodic chamber, CO ₂ was rapidly and selectively reduced to CO based on a porous carbon gas diffusion electrode (GDE) modified with polytetrafluoroethylene and cobalt phthalocyanine (CoPc). A high Faraday efficiency (>95%) toward CO was achieved due to the enhanced mass transfer of CO ₂ on the GDE and the presence of the selective CoPc catalyst. The maximum energy efficiency of the system was more than 72.41% with a current density of over 50 mA/cm ² , which was 12.5 times higher than what was previously reported on the H ₂ S treatment system. The yields of S and CO were 24.94 mg·cm ^-2 ·h ^-1 and 19.93 mL·cm ^-2 ·h ^-1 , respectively. A model analysis determined that the operation cost of the synchronous utilization of H ₂ S and CO ₂ method was slightly lower than that of the single utilization of H ₂ S in the existing natural gas purification technology. Overall, this paper provides efficient and simultaneous conversion of H ₂ S and CO ₂ into S and CO.