摘要
目前,钙钛矿材料在汽车尾气催化处理、污水处理及燃料电池等方面应用广泛,但在抑制热裂解结焦涂层应用方面鲜有报道。本文以磷酸二氢铝为黏结剂,采用浆料法在HP40不锈钢基体表面制备了La_(1−x)Sr_(x)MnO_(3)钙钛矿涂层,采用X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)和Raman光谱考察了La_(1−x)Sr_(x)MnO_(3)钙钛矿涂层及表面焦层的物相组成和微观结构,利用X射线光电子能谱(XPS)研究了涂层组成元素的化学状态,通过石脑油热裂解结焦实验评价了涂层的抗结焦效果。结合材料表征与实验结果,阐述了涂层抗结焦机理。表征结果显示,La_(1−x)Sr_(x)MnO_(3)钙钛矿涂层涂覆均匀,厚度约为30μm,与基底贴合紧密,粒子之间结合较好,但表面存在少量微孔;La_(1−x)Sr_(x)MnO_(3)钙钛矿氧化物具有明显的立方晶体特征,Sr进入LaMnO_(3)晶格未改变钙钛矿晶相结构;与未经掺杂的LaMnO_(3)涂层相比,Sr掺杂后的钙钛矿表面吸附氧含量与晶格氧含量之比O_(ads)/O_(latt)更高,而且涂层中氧空位的数量增加。热裂解结焦实验结果表明,钙钛矿涂层的抗结焦性能随着Sr含量的提高而增强,当裂解时间为3h和5h时,La_(0.2)Sr_(0.8)MnO_(3)涂层的抑制结焦效果分别可达到84.88%和82.31%。钙钛矿涂层结构不仅通过屏蔽基底金属的催化活性抑制了催化结焦过程,还通过催化焦炭氧化燃烧反应进一步减少热裂解焦炭的沉积。其中,Sr的掺杂可促进氧空位形成,增加氧的流动性,从而促进电子转移,进一步提高催化焦炭燃烧反应的活性。钙钛矿La_(1−x)Sr_(x)MnO_(3)涂层的涂覆会导致焦层中无序化焦炭的比例增加,焦炭的石墨化程度降低,有利于后续的清焦操作。
At present,perovskite materials are widely used in the treatment of automobile tail gas,sewage treatment and fuel cell.However,there are limited reports on the application of those materials in coking inhibition during the thermal cracking of hydrocarbons.In this paper,La_(1−x)Sr_(x)MnO_(3)perovskite-type coatings were prepared by the slurry method on the HP40 stainless steel substrate with aluminum dihydrogen phosphate as the binder.The phase composition and microstructure of the coatings and the coke layers were characterized by XRD,SEM,EDS and Raman spectroscopy.The chemical states of the elements in the coatings were analyzed by XPS.The coking inhibition performance of the coatings were evaluated through the pyrolysis of naphtha.The results showed that La_(1−x)Sr_(x)MnO_(3)perovskite coatings were uniformly formed on the metal surface with a thickness of about 30μm and well adhered to the substrate.The coating particles were tightly bonded although a small amount of micropores were presented in the coatings.La_(1−x)Sr_(x)MnO_(3)perovskite oxides presented a featured cubic crystal structure.Furthermore,the incorporation of Sr into the lattice of LaMnO_(3)did not change the perovskite phase.Compared with undoped LaMnO_(3)perovskite coating,the doping of Sr into the coatings resulted in the higher ratios of O_(ads)/O_(latt)and the formation of more oxygen vacancies.The anti-coking rate was increased with the doping content of Sr in the coating.When the cracking time were 3h and 5h,the coking inhibition rates were 84.88%and 82.31%,respectively.La_(1−x)Sr_(x)MnO_(3)perovskite coatings not only suppressed the catalytic coking by blocking the activity of the substrate metal but also mitigated the coke deposition by catalyzing the oxidation combustion of the coke deposits.Moreover,the doping of Sr into the coatings generated more oxygen vacancies which increased oxygen mobility and promoted electron transfer,and thus improved the catalytic activity of coke combustion.An increased proportion of disordered cok
作者
梁贻景
马岩
卢展烽
秦福生
万骏杰
王志远
LIANG Yijing;MA Yan;LU Zhanfeng;QIN Fusheng;WAN Junjie;WANG Zhiyuan(Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering,School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China)
出处
《化工进展》
EI
CAS
CSCD
北大核心
2023年第4期1769-1778,共10页
Chemical Industry and Engineering Progress
基金
国家自然科学基金(21706159)。
关键词
热解
钙钛矿
界面
催化
焦炭
pyrolysis
perovskite
interface
catalysis
coke deposits
