A novel chemical engineering system design for synergistic SO2 reduction and CH4/CO2 reforming.

The SO2 reduction to elemental sulfur by CH4 is an essential method for industrial SO2 treatment and resource utilization, however, its application has been limited by high temperature requirement and CO2 emissions. Herein, we propose a novel chemical engineering design integrating SO2 reduction and CH4/CO2 reforming. By partial reflux of syngas and H2S, SO2 can be reduced into H2S below 450 °C, which is 400 °C lower than direct reduction by CH4. The H2S serves as the promoter for CH4/CO2 reforming to produce syngas, making CH4 conversion increase from 32% to 89% at 900 °C. The integrating process proves its feasibility that SO2 and CH4 are converted into H2, CO and elemental sulfur, with desirable sulfur recovery and carbon emission management at various operation modes. The modeling and simulation results show that this system has remarkable thermodynamic advantages due to the heat exchange between SO2 reduction and CH4/CO2 reforming, making the heat loads decrease by one-third to half. The chemical engineering system provides a novel strategy for synergistic SO2 and CO2 utilization, with potential for syngas and sulfur co-production.