Study on Regeneration Method of Al2O3-based Catalyst after Hydrolysis of Carbonyl Sulfide
The hydrolysis of carbonyl sulfide(COS)aims to catalytically convert the difficult organic sulfur COS into the inorganic H2S that can be easily removed.This technology is considered a crucial means for indirectly organic sulfur removal from industrial flue gases.The biggest challenge of COS hydrolysis technology is to maintain the activity and stability of cata-lysts,which are often deactivated due to sulfur accumulation and surface sulfation poisoning.Exploring a simple and reliable method for catalyst regeneration is an essential approach to enhance the practicality and cost-effectiveness of COS hydrolysis technology.In this study,a catalyst regeneration method of"calcination+washing"has been developed for restoring the deac-tivated Al2O3-based catalysts after COS hydrolysis,according to their poisoning mechanisms.Results show that only when the calcination temperature exceeds 650 ℃,the activity of Al2O3 catalyst can be restored after washing,achieving a COS conver-sion of over 98％in the short term.As the reaction time increases to 8 hours,the catalyst is gradually deactivated again.In the case of La-Al2O3 catalyst,when the calcination temperature is 550 ℃,650 ℃ or 850 ℃,the catalyst activity can be com-pletely restored,the hydrolysis conversion rate remains above 99.5％within 8 h,and the activity does not decrease signifi-cantly with the extension of reaction time.Characterization results showed that although the surface ratio of the catalysts could be slightly increased due to deposited sulfur after deactivation,the mass transfer was hindered due to the decrease of the aver-age pore diameter,which seriously affected the catalyst activity.The regeneration method of"roasting+washing"has obvious effect on the removal of deposited sulfur,and the recovery of pore structure is the main reason for the recovery of catalyst activ-ity.
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