Structural Properties and Catalytic Activity of Sr-Substituted LaFeO3 Perovskite

Partial substitution of La3+ by Sr2+ in LaFeO3 resulted in significant changes in its structure and catalytic activity. The perovskite structure was changed from orthorhombic in LaFeO3 to nearly cubic in La0.8Sr0.2FeO3. Replacement of La3+ by Sr2+ induced a positive charge deficiency that was compensated for by the oxidation of some Fe3+ to Fe4+ and the generation of oxygen vacancies, which greatly promoted the reducibility of the perovskite. La0.8Sr0.2FeO3 gave considerably enhanced activity in CO oxidation and methane combustion because the oxygen vacancies accelerated the dissociation of gaseous oxygen on the surface in CO oxidation and facilitated the diffusion of lattice oxygen from the bulk to the surface during CH4 combustion.

摘要Sr2+对 La3+的部分取代导致 LaFeO3 的结构性质和催化性能发生了显著变化. 钙钛矿结构由 LaFeO3 的正交型变成了 La0.8Sr0.2FeO3 的近立方型. 由于电荷补偿效应, Sr2+取代 La3+导致部分 Fe3+氧化为 Fe4+, 同时产生氧空穴, 因而提高了 La0.8Sr0.2FeO3 的还原性能. 由于氧空穴的作用, La0.8Sr0.2FeO3 催化剂在 CO 氧化和 CH4 燃烧反应中均表现出较 LaFeO3 高的催化活性. 在 CO 氧化反应中, 氧空穴有利于反应物分子的吸附并加速了气相氧分子在表面上的解离; 而在 CH4 燃烧反应中, 氧空穴则促进了晶格氧物种从体相到表面的扩散.

Sr substitution in LaFeO3 induced the generation of oxygen vacancies, which facilitated the dissociation of gaseous oxygen and diffusion of lattice oxygen, and enhanced the activity for CO oxidation and methane combustion.Figure optionsDownload as PowerPoint slide