CIESC Journal ›› 2016, Vol. 67 ›› Issue (12): 5015-5023.DOI: 10.11949/j.issn.0438-1157.20160272

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Oxidation transferring mechanism of SO2 in FCC flue gas over CeO2 surface

LIU Yifeng, SHEN Benxian, PI Zhipeng, CHEN Hua, ZHAO Jigang   

  1. Research Institute of Petroleum Processing, East China University of Science and Technology, Shanghai 200237, China
  • Received:2016-03-08 Revised:2016-09-06 Online:2016-12-05 Published:2016-12-05

CeO2表面氧化转移FCC烟气中SO2的反应过程

刘逸锋, 沈本贤, 皮志鹏, 陈华, 赵基钢   

  1. 华东理工大学石油加工研究所, 上海 200237
  • 通讯作者: 赵基钢。zig@ecust.edu.cn

Abstract:

To improve efficiency of Ce-based desulfurization agent in deep desulfurization of flue gas in fluid catalytic cracking(FCC) petroleum processing, reaction mechanism of SO2 and O2 over CeO2 surface were investigated in both experiments and calculations by density functional theory(DFT). SO2 removal from simulated flue gas with O2 presence was carried out over CeO2 under 60℃ and 200℃. CeO2 characterization before and after desulfurization by XRD, IR and XPS was used to study changes in valence and relative amount of S and Ce as well as to explore possible oxidative reaction path of SO2. Models of monomolecular O2 adsorption and bimolecular O2 and SO2 adsorption on O-deficient CeO2(111) and MgAl2O4(111) were established from DFT simulation. SO2 oxidation and energy barriers of each reaction step were calculated using LST/QST method. Results indicated that CeO2(111) had better catalytic effect for SO2 desulfurization than MgAl2O4(111) and CeO2 could transport lattice oxygen in oxidation with SO3 desorption as rate-control step.

Key words: petroleum, FCC flue gas deep desulfurization, XPS, molecular simulation, adsorption, lattice oxygen transport, rate-control step

摘要:

为提高Ce基脱硫助剂对石油加工过程中流化催化裂化(FCC)烟气深度脱硫效果,采用实验与密度泛函理论(DFT)探究了SO2、O2在CeO2表面的反应过程。通过60℃、200℃反应温度下SO2、O2与CeO2的反应,对反应前后CeO2样品的XRD、IR、XPS谱图比较分析,探索S、Ce的价态变化和相对含量转变规律,从而推测SO2可能的反应路径。基于密度泛函理论模拟构造了O2单分子和SO2、O2双分子在CeO2(111)和MgAl2O4(111)O空位表面可能产生的吸附构型;利用LST/QST方法搜索SO2氧化反应过程,计算各步反应能垒。结果表明CeO2(111)相比MgAl2O4(111)具有更好的SO2催化效果,其中CeO2在反应中起到了晶格O传递作用,并进一步推断SO3的脱附过程是整个反应的速率控制步骤。

关键词: 石油, FCC烟气深度脱硫, XPS, 分子模拟, 吸附, 晶格O传递, 速控步骤

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