Direct Utilization of Elemental Sulfur in the Synthesis of Microporous Polymers for Natural Gas Sweetening

Elemental sulfur, which is produced by a process called hydrodesulfurization mainly as a byproduct of the purification of natural gas, is one of the most abundant elements in the world. Herein, we describe solvent-and catalyst-free synthesis of ultramicroporous benzothiazole polymers (BTAPs) in the presence of elemental sulfur in quantitative yields. BTAPs were found to be highly porous and showed exceptional physiochemical stability. Moreover, in situ chemical impregnation of sulfur within the micropores increased CO2 affinity of the sorbent while limiting diffusion of CH4. As low-cost, scalable solid sorbents, BTAPs showed promising CO2 separation ability and high regenerability under vacuum swing adsorption for the simulated flue gas, natural gas, and landfill gas conditions. The fact that elemental sulfur can be directly utilized in the synthesis of BTAPs means that it can be recycled back to the natural gas sweetening process for efficient CO2/CH4 separation, thus offering a high-value, scalable, large-scale application for elemental sulfur.