物理化学学报2023，Vol.39Issue(9)：109-118,10.DOI:10.3866/PKU.WHXB202210038
钾改性氧化铝基羰基硫水解催化剂及其失活机理
Deactivation Mechanism of COS Hydrolysis over Potassium Modified Alumina
摘要
Abstract
Carbonyl sulfide(COS)is commonly found in conventional fossil fuels,such as nature gas,oil-associated gas,and blast-furnace gas,and its untreated emission not only corrodes pipelines and poisons catalysts but will also inevitably pollute the environment and endanger human health.Catalytic hydrolysis is recognized as the most promising strategy to eliminate COS because it can be performed under mild reaction conditions with a high removal efficiency.Notably,alkali metals promote catalytic COS hydrolysis over Al2O3 owing to their electron donor properties,basicity,and electrostatic adsorption.However,despite the significant attraction of using potassium-promoted Al2O3(K2CO3/Al2O3)as conventional catalysts for COS hydrolysis,the mechanism of COS hydrolysis over K2CO3/Al2O3 remains unclear and is controversial owing to the complex composition of the K species.In this study,commercial Al2O3 modified with potassium and sodium salts were synthesized using the wet impregnation method and characterized by various techniques.Based on the results of the activity measurements,the K2CO3-,K2C2O4-,NaHCO3-,Na2CO3-,and NaC2O4-modified catalysts had a positive effect on COS hydrolysis.Among them,the K2CO3/Al2O3 catalyst exhibited the highest COS conversion.Notably,the K2CO3/Al2O3 catalyst exhibited an excellent catalytic performance(～93％,20 h),which is significantly better than that of pristine Al2O3(～58％).Furthermore,this study provides strong evidence for the role of H2O during catalytic hydrolysis over K2CO3/Al2O3 using in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and X-ray photoelectron spectroscopy(XPS).The in situ DRIFTS analysis revealed that hydrogen thiocarbonate formed as an intermediate during COS hydrolysis over K2CO3/Al2O3.Meanwhile,the XPS findings suggested that sulfates and elemental sulfur accumulated on the catalyst surface,which may have contributed to catalyst poisoning.Additionally,the effect of water vapor content in the reaction pathway of COS hydrolysis over K2CO3/Al2O3 was investigated.The presence of excess water resulted in a reduction in catalytic activity owing to competitive adsorption between H2O and COS molecules on the catalyst surface.The enhancement in the catalytic activity over K2CO3/Al2O3 may be attributed to the formation of HO-Al-O-K interfacial sites.More importantly,all the catalysts were used under industrially relevant conditions,which provides valuable theoretical guidance for practical applications in the future.Thus,this detailed mechanistic study reveals new insights into the roles of the interfacial K co-catalyst,which provides a new opportunity for the rational design of stable and efficient catalysts for COS hydrolysis.关键词
羰基硫/催化水解/HO-Al-O-K界面活性位点/失活机理/工业工况条件Key words
Carbonyl sulfide/Catalytic hydrolysis/HO-Al-O-K interface site/Deactivation mechanism/Industrial-relevant condition分类
化学引用本文复制引用
雷淦昌,郑勇,曹彦宁,沈丽娟,王世萍,梁诗景,詹瑛瑛,江莉龙..钾改性氧化铝基羰基硫水解催化剂及其失活机理[J].物理化学学报,2023,39(9):109-118,10.基金项目
The project was supported by the National Natural Science Foundation of China(21825801,22208053,22178057,21878053,22278073,22208055,22078063)and the Natural Science Foundation of Fujian Province(2020H6007,2022J05131).国家自然科学基金(21825801,22208053,22178057,21878053,22278073,22208055,22078063)及福建省自然科学基金(2020H6007,2022J05131)资助项目 （21825801,22208053,22178057,21878053,22278073,22208055,22078063）
