Solvent-free molten co-assembly of ordered mesoporous carbon for efficiently supported adsorption and separation of SO2

Abstract

Developing supported polytertiary amine solid adsorbents has great significance for highly reversible capture of SO₂ from industrial tail gas. We report here a novel solvent-free molten co-assembly of block copolymer templates with a phenolic precursor and silica species to rationally design ordered mesoporous carbon–silica nanocomposites, silica and carbon (OMC). The prepared OMC possesses high BET surface area (1450 m² g⁻¹), large pore volume (1.8 cm³ g⁻¹), and ordered and uniform mesopores (8.7 nm). In view of this, the methylated-polyethyleneimine (mPEI) was physically encapsulated into OMC, and the synthesized OMC@mPEI-x were systematically characterized and investigated for selective capture and separation of SO₂. In comparison with many other supported adsorbents, the OMC@mPEI-x exhibit excellent performance for SO₂ reversible adsorption, particularly at low pressures (9.0 mmol g⁻¹, 25 °C and 0.1 bar), giving record high SO₂/CO₂ IAST selectivity (1789). Meanwhile, OMC@mPEI-x also displayed superior performance for continuous separation of SO₂ from an SO₂/N₂/CO₂ mixture, and their saturation breakthrough sulfur capacity (6.9 mmol g⁻¹, 25 °C) and breakthrough time (775 min g⁻¹, 25 °C) were far better than those of many reported solid adsorbents, demonstrating that they can be applied as efficient and stable solid adsorbents for selective adsorption and separation of SO₂ from industrial processes.