Waste to Wealth: Discarded Cigarette Butt-Derived Metal-Free N-Rich Carbon Catalysts for the Selective Catalytic Oxidation of Hydrogen Sulfide to Sulfur
Jintao Yang, Shuo Cui, Fei Zhao, Fang Wang, Jiayu Feng, Ping Ning, Lijuan Jia
Abstract
The selective catalytic oxidation of toxic gas H 2 S to elemental sulfur (H 2 S-SCO) is a promising desulfurization process known for its dual benefits of recovering valuable sulfur resources and mitigating environmental pollution. Nevertheless, developing cost-effective and efficient catalysts for H 2 S-SCO remains a significant challenge. In this study, we synthesized a low-cost and metal-free nitrogen-rich carbon catalyst (NrCC) by copyrolyzing discarded cigarette butts (organic solid wastes that are difficult to degrade naturally) with urea for the continuous H 2 S-SCO process at a relatively low temperature. The NrCC exhibited exceptional catalytic performance, achieving complete H 2 S conversion to sulfur at 180 °C, and demonstrated excellent stability in humid (RH = 80%) and high CO 2 concentration environments. The catalyst succeeded due to its developed pore structure (specific surface area as high as 2267.77 m 2 ·g –1 ) and abundant pyridine-N sites. DFT calculations showed that the pyridine-N neighbor carbon sites were the active sites promoting H 2 S adsorption and dissociation. This study presents a novel “waste control by waste” strategy that integrates the utilization of organic solid waste resources with air pollution control measures, showcasing the potential for sustainable environmental solutions.