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SO_2、O_2在CeO_2表面的反应过程。通过60℃、200℃反应温度下SO_2、O_2与Ce O_2的反应,对反应前后CeO_2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SO_2可能的反应路径。基于密度泛函理论模拟构造了O_2单分子和SO_2、O_2双分子在CeO_2(111)和Mg Al_2O_4(111)O空位表面可能产生的吸附构型;利用LST/QST方法搜索SO_2氧化反应过程,计算各步反应能垒。结果表明Ce O_2(111)相比MgAl2O_4(111)具有更好的SO_2催化效果,其中CeO_2在反应中起到了晶格O传递作用,并进一步推断SO_3的脱附过程是整个反应的速率控制步骤。
To improve efficiency of Ce-based desulfurization agent in deep desulfurization of flue gas in fluid catalytic cracking（FCC） petroleum processing, reaction mechanism of SO_2 and O_2 over Ce O_2 surface were investigated in both experiments and calculations by density functional theory（DFT）. SO_2 removal from simulated flue gas with O_2 presence was carried out over CeO_2 under 60℃ and 200℃. Ce O_2 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 SO_2. Models of monomolecular O_2 adsorption and bimolecular O_2 and SO_2 adsorption on O-deficient Ce O_2（111） and Mg Al_2O_4（111） were established from DFT simulation. SO_2 oxidation and energy barriers of each reaction step were calculated using LST/QST method. Results indicated that Ce O_2（111） had better catalytic effect for SO_2 desulfurization than Mg Al_2O_4（111） and Ce O_2 could transport lattice oxygen in oxidation with SO_3 desorption as rate-control step.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2016年第12期5015-5023,共9页
CIESC Journal
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
petroleum
FCC flue gas deep desulfurization
XPS
molecular simulation
adsorption
lattice oxygen transport
rate-control step
