Construction of low-temperature regenerable dual-functional AlCeZr adsorbent and its synergistic conversion mechanism for simultaneous removal of COS and CS2

Limited studies on the treatment technology for the simultaneous and efficient removal of COS and CS 2 are reported. An innovative approach was adopted to combine basic sites (Lewis acid sites) with transition metal oxides to create a bi-functional AlCeZr composite adsorbent with both hydrolysis and oxidation activities, which could be used for the simultaneous and efficient removal of COS and CS₂. The simultaneous removal performance of COS and CS₂ was investigated by regulating the molar ratio of pseudo-boehmite to cerium-zirconium solid solution. The AlCeZr adsorbent before and after adsorption were characterized by DRIFTS, FT-IR, TG-DTG, BET, and XPS, and the mechanism of simultaneous adsorption, hydrolysis, and oxidation of COS and CS₂ were explored. Moreover, the low-temperature regeneration performance of the AlCeZr adsorbent was evaluated. The results show that the breakthrough sulfur capacity of Al 5 Ce 0.7 Zr 0.3 (the molar ratio of Al/CeZr of 5:1) reaches 31.85   mg S/g ads under the conditions of an adsorption temperature of 90 °C, a space velocity of 2000 h⁻¹ with water vapor content of 2 vol.% and oxygen content of 0.5 vol.%. An appropriate amount of water vapor allows water molecules to repair Al-OH sites through hydrogen bonding, while oxygen maintains the concentration of Al-O* active sites via a lattice oxygen vacancy compensation mechanism (Ce³⁺/Ce⁴⁺ redox cycle). The lattice oxygen (O²⁻) in the Ce-Zr solid solution forms an electron transfer channel with Al-OH, promoting the directional conversion of H₂S intermediates to generate Ce₂(SO₄)₃. The Al 5 Ce 0.7 Zr 0.3 achieves a regeneration efficiency of over 98% at 150 °C (approximately 50-350 °C lower than that of industrial regeneration temperature reported in the literature), and shows efficient low-temperature desulfurization and regeneration capability, which has a promising application prospect.