Conversion of coal into N-doped porous carbon for high-performance SO₂ adsorption

The large-scale burning of coal has led to increasingly serious SO₂ environmental pollution problems. The SO₂ adsorption and removal technology based on porous carbons has the advantages of less water consumption, no secondary pollution, recycling of pollutants, and renewable utilization of adsorbents, in contrast to the wet desulfurization process. In this work, we developed a series of N-doped coal-based porous carbons (NCPCs) by calcining a mixture of anthracite, MgO, KOH and carbamide at 800 °C. Among them, the NCPC-2 sample achieves a high N-doped amount of 1.29 at%, and suitable pores with a specific surface area of 1370 m² g^-1 and pore volume of 0.62 cm³ g^-1. This N-doped porous carbon exhibits excellent SO₂ adsorption capacity as high as 115 mg g^-1, which is 3.47 times that of commercial coal-based activated carbon, and 2 times that of NCPC-0 without N-doping. Theoretical calculations show that the active adsorption sites of SO₂ are located at the edges and gaps of carbon materials, and surface N doping enhances the adsorption affinity of carbon materials for SO₂. In addition, the NCPCs prepared in this work are rich in raw materials and cheap, which meets the needs of industrial production, having excellent SO₂ adsorption capacity.