掺杂稀土锆酸盐的制备、结构及催化性能研究

发布时间：2018-02-19 18:27

本文关键词： 自蔓延燃烧法烧绿石型 Ln_2Zr_2O_7纳米晶荧光性质光催化性能高氯酸铵催化剂　出处：《南京理工大学》2015年博士论文　论文类型：学位论文

【摘要】：制备新型纳米及亚微米级材料是当今材料领域研究的热点之一。本文以具有高的导电性、高化学稳定性、高催化活性的烧绿石型稀土锆酸盐(Ln2Zr2O7)为研究对象,通过寻求绿色的合成手段,在相对温和的环境中获得尺寸小、分散性好的纳米粒子。本文将软化学法运用到其制备过程中,制备出了系列Ln2Zr2O7为基础的掺杂纳米材料,研究了其结构、形貌以及光催化性能等,主要内容如下:采用了一种软化学法—盐助甘氨酸自蔓延燃烧法,在较低的温度下制备了系列Ln2Zr2O7(Ln = La,Nd,Sm,Eu,Dy,Er),系统研究了 Ln 对 Ln2Zr2O7 晶体结构的影响;初步研究了反应机理。结果表明盐助甘氨酸自蔓延燃烧法所制得产物的团聚少,粒子粒径分布均匀,平均粒径在30 nm左右。对所制备的Ln2Zr2O7系列产物的光催化活性进行了研究,结果发现,合成的产物均有好的光催化活性,Ln的种类对Ln2Zr2O7系列的催化活性有较大的影响,其光催化活性的顺序为Dy2Zr2O7Nd2Zr2O7Er2Zr2O7Sm2Zr2O7La2Zr2O7。在这个体系中随着原子序数的增加,纳米晶的光催化活性变化规律与稀土金属阳离子Ln3+磁矩的变化规律一致。说明稀土离子的光催化活性与Ln3+磁矩同源于4f电子结构。系统研究了 A位的Ln部分被其他Ln取代的La_(2-x)Ln_xZr_2O_7系列化合物的制备及光催化性能,采用软化学法—盐助甘氨酸自蔓延燃烧法,制备了系列La2-xLnxZr7O7(Ln =La,Nd,Sm,Eu,Dy,Er)纳米晶。结果表明,A位置的La可以被其他镧系元素Ln取代,而不改变其晶型。Ln实际上代替了 La掺杂进入其晶格中,产物为单一晶相的固溶体。通过盐助甘氨酸自蔓延燃烧法制备了高分散的,粒度分布均匀,粒子尺寸约20nm～40 nm的La_(2-x)Ln_xZr_2O_7系列化合物。并对产物的荧光性质及光催化性能进行了系统研究。采用盐助甘氨酸自蔓延燃烧法合成了 A位的Ln部分被过渡金属取代的Ln_(2-x)M_xZr_2O_7系列化合物,得到了单一相的固溶体。结果表明,Ln3+可以被M3+置换,且不改变晶型,产物为单一相的烧绿石型固溶体。而且所制备的粒子分布均匀,形状规则,分散性好。同时研究了其光催化活性,结果发现Ln_(2-x)M_xZr_2O_7系列具有好的催化活性。采用盐助甘氨酸自蔓延燃烧法制备的A位的Ln部分被取代的La_(2-x)Ln_xZr_2O_7和Ln_(2-x)M_xZr_2O_7系列化合物,研究其对高氯酸铵(AP)热分解的催化性能。采用DSO/TG-MS联用技术研究了 Ln_(2-x)M_xZr_2O_7对高氯酸铵的催化。结果表明,Ln_(2-x)M_xZr_2O_7对高氯酸铵(AP)有较强的催化作用,添加2%的Ln_(2-x)M_xZr_2O_7使高氯酸铵的分解温度降低,分解放热量增大。最大程度发挥了纳米催化剂的催化效能。与单纯的金属氧化物相比,掺杂烧绿石型的纳米粒子均表现出对高氯酸铵(AP)有较好的催化性能。采用盐助甘氨酸自蔓延燃烧法,以硝酸镝、硝酸钴和硝酸铈为原料,甘氨酸为燃烧剂,KCl为反应惰性盐,通过变化nGlycine/nM值、盐用量、煅烧温度控制纳米晶体的粒径,制备了立方晶系萤石型Dy2-xCoxCe2O7纳米晶。Dy3+可以被Co3+部分置换,且不改变晶型,产物为单一相的萤石型固溶体。所获得的纳米粒子具有良好的分散性,粒径约为18nm。采用DSC/TG-MS联用技术研究了 Dy1.9Co0.1Ce2O7对高氯酸铵的催化。结果表明,Dy1.9Co0.1Ce2O7对高氯酸铵(AP)有较强的催化作用,添加2%的Dy1.9Co0.1Ce2O7使高氯酸铵的分解温度降低近120℃,分解放热量从453.11 J/g增大到1337.68 J/g。说明加入纳米掺钴铈酸镝催化高氯酸铵(AP)热分解,催化效果优于相同条件下制备的纳米金属氧化物和未惨杂的铈酸镝。
[Abstract]:The preparation of a new type of nano and submicron materials is one of the hot spots in the field of materials research. This paper has a high conductivity, high chemical stability, pyrochlore type rare earth zirconate high catalytic activity (Ln2Zr2O7) as the research object, by seeking the green synthesis methods, in the phase of the soft environment in size small, scattered ions. The soft chemical method is used in the preparation process, the preparation of a series of Ln2Zr2O7 based doped nano material, studied its structure, morphology and photocatalytic properties. The main contents are as follows: using a soft chemical method - glycine salt assisted self propagating combustion method at low temperature to prepare a series of Ln2Zr2O7 (Ln = La, Nd, Sm, Eu, Dy, Er), studied the influence of Ln on the crystal structure of Ln2Zr2O7; preliminary study on reaction mechanism. The results show that the combustion method for glycine salt assisted self propagating The product had a little agglomeration and the particle size distribution, the average particle size of about 30 nm. The photocatalytic activity of Ln2Zr2O7 series of prepared samples were studied, the results showed that the photocatalytic activity of the synthesized products were good, has great influence on the catalytic activity of Ln species on the Ln2Zr2O7 series, the the photocatalytic activity of the order of Dy2Zr2O7Nd2Zr2O7Er2Zr2O7Sm2Zr2O7La2Zr2O7. in this system as the atomic number increases, consistent with the variation regularity of nanocrystals and photocatalytic activity of rare earth metal cation Ln3+ magnetic moment. The photocatalytic activity of rare earth ions and Ln3+ moment homology to the electronic structure of 4f system. The effect of Ln A is replaced by Ln La_ (2-x) preparation and photocatalytic properties of Ln_xZr_2O_7 compounds, using soft chemical method - glycine salt assisted self propagating combustion method, a series of La2-xLnxZr7O7 were prepared (Ln =La Nd, Sm, Eu, Dy, and Er) nanocrystals. The results show that the location of A La can be used by other lanthanide substituted Ln, and not change the crystal type of.Ln actually replaced La doped into the lattice, the products were single phase solid solution. The salt assistant glycine SHS method preparation of highly dispersed combustion, uniform particle size distribution, particle size of about 20nm ~ 40 nm La_ (2-x) Ln_xZr_2O_7 series compounds. And fluorescence properties and photocatalytic properties of the products were studied. Using salt assistant glycine self propagating combustion synthesis of Ln A is part of a transition metal substituted Ln_ (2-x) M_xZr_2O_7 series of compounds, the single phase solid solution. The results show that Ln3+ can be M3+ replacement, and does not change the crystal type, product is single pyrochlore type solid solution. And the preparation of uniform particle size distribution, regular shape and good dispersion. At the same time on the light catalytic activity And the results showed that Ln_ (2-x) M_xZr_2O_7 has good catalytic activity. The salt assistant glycine SHS prepared by A Ln was partially substituted La_ (2-x) Ln_xZr_2O_7 and Ln_ (2-x) M_xZr_2O_7 series of compounds, the study of ammonium perchlorate (AP) thermal decomposition. The catalytic performance based on DSO/TG-MS technology Ln_ (2-x) M_xZr_2O_7 catalyst of ammonium perchlorate. The results showed that Ln_ (2-x) M_xZr_2O_7 of ammonium perchlorate (AP) has a strong catalytic effect, the addition of 2% Ln_ (2-x M_xZr_2O_7) to lower the decomposition temperature of ammonium perchlorate decomposition heat release increased. Maximize the catalytic performance of nanometer catalyst. Compared with pure metal oxide nanoparticles, doped pyrochlore type showed on ammonium perchlorate (AP) has better catalytic properties. By combustion method salt assistant glycine nitrate self propagating in dysprosium cobalt nitrate and cerium nitrate as raw The material, glycine as combustion agent, KCl as reaction inert salt, by changing the nGlycine/nM value, salt dosage and calcination temperature control of the particle size of the nanocrystals, prepared cubic fluorite type nanocrystalline Dy2-xCoxCe2O7.Dy3+ can be Co3+ replacement, and does not change the crystal type, the product is single phase fluorite type solid solution. The obtained nanoparticles have good dispersion, particle size of about 18nm. technology to study the catalytic Dy1.9Co0.1Ce2O7 of ammonium perchlorate by DSC/TG-MS. The results showed that Dy1.9Co0.1Ce2O7 of ammonium perchlorate (AP) has a strong catalytic effect, add 2% of Dy1.9Co0.1Ce2O7 so that the decomposition temperature of the ammonium perchlorate reduction of up to 120 DEG C the heat decomposition, increases from 453.11 J/g to 1337.68 J/g. nano cobalt doped cerium dysprosium acid catalytic ammonium perchlorate (AP) thermal decomposition, catalytic effect is better than that under the same conditions for preparation of nano metal oxide and doped cerium Dysprosium acid.

【学位授予单位】：南京理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB383.1;O643.36

【参考文献】