Optimization of hydrogen sulfide adsorption performance by tar based porous carbon prepared by template method

This study provides a method of preparation of tar based porous carbon (TPC) for H2S adsorption by high-temperature carbonization with tar as precursor and zinc chloride (ZnCl2) as template. Response surface methodology (RSM) was used to systematically investigate the effects of carbonization temperature, mass percentage of template and carbonization time on the cumulative adsorption (CAC) of H2S. The adsorption kinetics and isotherms, thermodynamics, and TPC's properties were explored to obtain its adsorption mechanism on H2S. The results demonstrate that TPC was a microporous material with a rich surface functional group structure. The specific surface area and pore volume of the optimal sample (TPC-750-66-90) could reach 890.08 m2/g and 0.440 cm3/g, respectively, accompanied by a CAC of 34.01 mg/g. FTIR and XPS analysis results indicate that there were abundant oxygen- and nitrogen-containing groups on the surface of TPC, which helped to promote the chemisorption on H2S. The adsorption kinetics and isotherms fitting and thermodynamic calculation of H2S adsorption demonstrate that both physisorption and chemisorption played important roles, and the adsorption was a spontaneous, exothermic, random, and monolayer process. According to the regeneration tests, TPC could maintain at least 70% of its initial capacity after three rounds of regeneration. All the above results demonstrated that porous carbon preparation through high-temperature carbonization is a promising method for tar utilization, and the prepared porous carbon as adsorbent for gas pollutants like H2S has wide application potential in areas including kitchen trash, sewage treatment facilities, and biogas purification.