Porous sulphur copolymer for gas-phase mercury removal and thermal insulation

•Porous sulfur copolymer foams were synthesized with divinylbenzene as comonomer.•Foams are used in gas phase removal of mercury.•Performance of these foams in mercury removal is comparable to carbon foams.•Foams exhibit low thermal conductivities due to high porosity.•Sulfur intrinsic low thermal conductivity also contribute to the above.

Removal of gas-phase mercury is vital in gas processing industries. Herein, we report the preparation of porous sulphur copolymers for capturing elemental mercury (Hg(0)) in the gas phase. Porous sulphur copolymers were prepared using porogen and an inverse-vulcanisation technique. Sulphur powder was mixed with a water-soluble porogen (NaCl) and cross-linked with divinyl benzene (DVB) at 165 °C, and the porous structure was later obtained by dissolving the porogen in water. The porosity of the copolymer was controlled by varying the amount of salt and cross-linker. The effect of pore volume and temperature on the adsorption of mercury from gas phase has been estimated. Samples with larger pore volumes showed a significant increase in adsorption capacity, reaching approximately 151 µg/g at 60 °C. High sulphur content and the porous structure enhanced the adsorption capacity. Furthermore, the thermal conductivities of the porous copolymers were studied at a range temperature. Copolymers with relatively high cross-link densities showed the very low thermal conductivity of approximately 0.048 W/m K at 25 °C, which is much lower than that of pristine sulphur. Abundant availability of sulphur and a simple method of preparation could make porous sulphur copolymers potential candidates for mercury capture and thermal insulation.

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