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

作　　者：雷淦昌 郑勇 曹彦宁 沈丽娟 王世萍[1,2] 梁诗景 詹瑛瑛 江莉龙 Ganchang Lei;Yong Zheng;Yanning Cao;Lijuan Shen;Shiping Wang;Shijing Liang;Yingying Zhan;Lilong Jiang(National Engineering Research Center of Chemical Fertilizer Catalyst,School of Chemical Engineering,Fuzhou University,Fuzhou 350002,China;China Fujian Innovation Laboratory of Chemical Engineering,Qingyuan Innovation Laboratory,Quanzhou 302801,Fujian Province,China;College of Environmental Science and Engineering,College of Carbon Neutral Modern Industry,Fujian Key Laboratory of Pollution Control&Resource Reuse,Fujian Normal University,Fuzhou 350007,China)

机构地区：[1]福州大学石油化工学院,化肥催化剂国家工程研究中心,福州350002 [2]中国福建化学工程科学与技术创新实验室,清源创新实验室,福建泉州302801 [3]福建师范大学环境与资源学院、碳中和现代产业学院,福建省污染控制与资源循环利用重点实验室,福州350007

出　　处：《物理化学学报》2023年第9期109-118,共10页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(21825801,22208053,22178057,21878053,22278073,22208055,22078063);福建省自然科学基金(2020H6007,2022J05131)资助项目。

摘　　要：天然气、油田伴生气、高炉煤气等化工生产过程中伴生COS气体,不仅会腐蚀管道和毒害催化剂,还会严重污染环境并危害人类健康。COS催化水解反应可在温和条件下高效的将COS脱除,是最具应用前景的COS脱除技术之一。碱金属元素因其具有独特的电子供体性质、表面碱性和静电吸附等特性,常被用作助催化剂以提高Al_(2)O_(3)的COS催化水解性能。近年来,以钾为助剂改性的Al_(2)O_(3)催化剂(K_(2)CO_(3)/Al_(2)O_(3))在COS催化水解反应中得到广泛的应用,但由于负载在Al_(2)O_(3)上的K物种的组成复杂,目前研究者对K_(2)CO_(3)/Al_(2)O_(3)催化剂上COS水解机理的理解仍存在一定的困惑和争议。本论文通过湿法浸渍法合成出一系列钾盐和钠盐改性的Al_(2)O_(3)催化剂,并利用各类先进的表征技术对这些催化剂进行分析。活性测试表明,以K_(2)CO_(3)、K_(2)C_(2)O_(4)、NaHCO_(3)、Na_(2)CO_(3)和NaC2O4改性Al_(2)O_(3)催化剂均有助于COS的水解。其中K_(2)CO_(3)/Al_(2)O_(3)拥有最佳的COS水解性能,连续运行20 h后其COS转化率仍高于~93%,远远优于未改性的Al_(2)O_(3)(~58%)。我们利用原位红外光谱和X射线光电子能谱探明了反应过程中催化剂的化学结构特征,阐明了H_(2)O分子在K_(2)CO_(3)/Al_(2)O_(3)上的水解作用机制。原位红外表明COS在K_(2)CO_(3)/Al_(2)O_(3)上的水解过程中形成了硫代碳酸氢盐中间产物。X射线光电子能谱表征证明催化剂的失活主要是因为催化剂表面积累了硫酸盐和单质硫。此外,我们还研究了水蒸气含量对COS水解性能的影响,研究发现,由于H_(2)O和COS分子在催化剂表面存在竞争吸附,过量的H_(2)O会引起催化活性的下降。上述研究表明,K_(2)CO_(3)/Al_(2)O_(3)催化剂上COS水解性能的提高主要是形成了HO-Al-O-K界面活性位。更为重要的是,所制备的催化剂都是在模拟工业工况条件下进行的,这为后续的工业应用提供了宝�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 Al_(2)O_(3)owing to their electron donor properties,basicity,and electrostatic adsorption.However,despite the significant attraction of using potassium-promoted Al_(2)O_(3)(K_(2)CO_(3)/Al_(2)O_(3))as conventional catalysts for COS hydrolysis,the mechanism of COS hydrolysis over K_(2)CO_(3)/Al_(2)O_(3)remains unclear and is controversial owing to the complex composition of the K species.In this study,commercial Al_(2)O_(3)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 K_(2)CO_(3)-,K_(2)C_(2)O_(4)-,NaHCO_(3)-,Na_(2)CO_(3)-,and NaC2O4-modified catalysts had a positive effect on COS hydrolysis.Among them,the K_(2)CO_(3)/Al_(2)O_(3)catalyst exhibited the highest COS conversion.Notably,the K_(2)CO_(3)/Al_(2)O_(3)catalyst exhibited an excellent catalytic performance(~93%,20 h),which is significantly better than that of pristine Al_(2)O_(3)(~58%).Furthermore,this study provides strong evidence for the role of H_(2)O during catalytic hydrolysis over K_(2)CO_(3)/Al_(2)O_(3)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 K_(2)CO_(3)/Al_(2)O_(3).Meanwhile,the XPS findings suggested that sulfates and elemental sulfur accumulated on the catalyst surface,which may have contributed to catalyst poison

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 

分 类 号：O643[理学—物理化学]