Study On The Modifiation Of Metal On Aluminium Oxide Catalyst And The Performance Of Carbonyl Sulfur Hydrolysis For Blast Furnace Gas

Desulphurization of blast furnace gas is a key to achieve ultra-low emissions in the whole process of iron-steel industry.The deactivation of carbonyl sulfur（COS）hydrolysis catalyst is an urgent problem to be solved in the application of hydrolysis technology,which is of great significance to achieve efficient removal of organic sulfur.It is important to investigate the influence of complex atmosphere in blast furnace gas on COS hydrolysis activity and the influence of active components on COS hydrolysis catalyst activity and anti-sulfur and anti-oxygen performance.In order to improve the COS hydrolysis activity,three kinds of hydrolysis catalysts with alkali metal Na/K,transition metal Fe and rare earth metal La as active components were prepared usingγ-Al₂O₃ as support.The influences of gaseous hourly space velocity and particle size on the COS hydrolytic activity over the catalyst were investigated on the fixed-bed gas chromatography combined device.And the influences of H₂O,H₂S,O₂ and CO₂ in blast furnace gas on the performance of catalyst were also explored.The physicochemical properties of the catalyst were characterized by Nitrogen Adsorption and Desorption,TPD,XPS and XRD techniques,and then the structure-activity relationship of the catalyst was analyzed.The reaction path of COS hydrolysis catalyst was deduced through in-situ-DRIFTS method.The main conclusions are as follows:The reaction mechanism of metal active center is clarified.The total volume pore and specific surface area of the modified catalyst decrease due to metal deposition.The alkalinity distribution on the catalyst was changed by the active component loading,and the number of weak alkalinity centers increased,but the number of medium and strong alkalinity centers decreased by K and Fe loading.The role of alkalinity center in COS hydrolysis process is elucidated,the weak alkalinity sites are the reaction center of COS hydrolysis,and the medium and strong alkalinity sites are the adsorption oxidation sites of H₂S.The reaction path of COS hydrolysis and the deactivation mechanism of catalyst were investigated.In the COS hydrolysis reaction,gaseous water vapor is adsorbed on the catalyst surface,the COS hydrolysis is consumed by the adsorbed H₂O.H₂S reacts with metal sites on the catalyst surface,and then is oxidized by lattice oxygen to elemental sulfur,metal sulfide or metal sulfate salts,which deposit on the catalyst surface and occupy the catalyst alkaline sites.This deactivation process is irreversible.The addition of active metal components can increase the activity of COS hydrolysis reaction,and the sulfur and oxygen resistance of hydrolysis catalyst.The influence of complex atmosphere on hydrolysis activity was expounded.In the process of COS hydrolysis,COS is the first-order reaction,while H₂O is the-1/2order reaction.It indicates that the excessive gaseous H₂O content leads to supersaturated adsorption of water vapor on the catalyst surface,and then hinders the adsorption of COS on the catalyst surface or blocks the catalyst pore.With the increase of H₂O content,the COS hydrolysis activity increases first and then decreases,and H₂O and COS compete for adsorption sites on the catalyst surface.The COS hydrolysis activity decreases with the increase of H₂S,O₂ and CO₂ content in the reaction gas,and the activity decreases significantly when H₂S and O₂ co-exist.The loading of active components slows down the toxic effect of H₂S and O₂ on the hydrolysis catalyst and improvs the resistance of the catalyst.