Catalytic hydrolysis of carbonyl sulfide over modified coal-based activated carbons by loading metal

Abstract

A novel type of metal oxide/activated carbon catalyst was prepared by sol-gel method for the hydrolysis of carbonyl sulfide (COS). The influences of the calcination temperature, additive content (2.5%–10.0% Fe₂O₃, mass fraction) and the basic density of the activation process were thoroughly investigated. The surface of catalysts was characterized by Boehm titration. The products were characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The results show that catalysts with 2.5%–5.0% Fe₂O₃ after calcining at 500 °C have superior activity. The conversion rate of COS increases with increasing the relative density of basic capacity loaded onto activated carbon(AC), and the activity follows the order: KOH>Na₂CO₃>NaHCO₃. Boehm titration data clearly show that the total acidity increases (from 0.06 to 0.48 mmol/g) and the basic groups decrease (from 0.78 to 0.56 mmol/g) after COS hydrolysis and H₂S adsorption. The XPS results show that the product of H₂S may be absorbed by the interaction with metal compounds and O₂ to form sulfate (171.28 eV) and element sulfur (164.44 eV), which lead to catalysts poisoning.

Keywords

carbonyl sulfide / activated carbon / metal oxide / hydrolysis