A_2BO_4型催化活性材料结构与性能的研究Ⅰ．［La_（k－x）Sr_x□_（1－k）］_2Cu_（1－y）□_yO_（4－δ）体系

Studies on the Structure and Properties of A_2BO_4 Type Materials in CatalysisⅠ[La_(1-k)]Sr_x□_(k-x)]_2Cu_(1-y)□_yO_(4-δ)series

以硝酸盐为原料，用柠檬酸络合法按［Ｌａ１－ｋＳｒｘ□ｋ－ｘ］２ＣｕＯ４（Ｘ＝０、０．０５、０．１、０．１５、０．２，ｋ＝０．０２５）的配比制备了５个样品．应用多晶Ｘ射线衍射法研究了此Ｌａ－Ｓｒ－Ｃｕ－Ｏ系列Ａ２ＢＯ４型复合氧化物的非完整结构．结构研究表明，此系列结构空位型非完整的存在，使结构中Ｂ位的铜离子变价为Ｃｕ２＋和Ｃｕ３＋．但是，随着Ａ位Ｓｒ加入量的增加，Ａ位空位的减少，结构中Ｂ位Ｃｕ３＋量随之减少，Ｃｕ２＋量随之增加，样品对于ＣＯ氧化的催化性能缓慢下降，而ＮＯ还原的催化能力增强．高价态的Ｃｕ３＋的存在是实现对ＣＯ催化氧化的条件；而Ｃｕ２＋给电子能力促进了Ｎｏ－的生成，是ＮＯ催化还原的活性来源．从此系列样品的催化性能和精细结构的研究可得出，适当地调节Ａ２ＢＯ４型结构中Ａ位和Ｂ位的空位及Ｓｒ２＋的掺入量，使Ｂ位Ｃｕ２＋和Ｃｕ３＋保持适当的比例，可获得ＣＯ催化氧化和ＮＯｘ催化还原同时具有较高活性的催化活性材料．

With the nitrates as raw material,five samples are prepared by the method of“citric acid complex”with the following composition[La(1-k)Srx□k-x]2CuO4(x=0.0,0. 05,0.1,0. 15,0.2,k =0. 025).The imperfect structures of a series of La-Sr-Cu-O A2BO4 type compounds have been worked out by polycrystalline X-ray diffractometry.There are vacancies at A、 B and O sites. These vacancies cause a partial change for the valence of Cu ions so that Cu(2+)and Cu(3+)coexist at the B site.Sr(2+)is dopen for substituting La(3+)and Occupies the vacancies at A site.With the increasing content of Sr2 t at the A site the content of Cu(3+) falls and weakens the catalytic function for CO oxidation while the content of Cu(2+) as electron donator rises and enhances the catalytic function for reduction. An appropriate proportion of Cu(2+) and Cu(3+)and vacancies at B site may be maintained by modifying the amount of vacancies and Sr(2+) properly which makes it possible to exhibit both oxidation and reduction catalytic function simultaneously. Consequently an extraordinary catalyst with high activity may be obtained for CO oxidation and Nox reduction.