稀土固体超强酸SO24-/TiO2/La3+催化合成醋酸丁酯

研究了以固体超强酸SO24-/TiO2/La3+催化剂,醋酸和正丁醇为原料合成醋酸丁酯,并考察了影响反应的因素.结果表明:醇酸物质的摩尔比为1.6:1、催化剂用量0.6 g、带水剂甲苯7 mL、反应时间2.5 h是最适宜的反应条件,其酯化率可达96.2%.     

稀土固体超强酸SO_4~(2-)/TiO_2/La~(3+)催化合成醋酸丁酯

研究了以固体超强酸 SO2 -4 /Ti O2 /La3+催化剂 ,醋酸和正丁醇为原料合成醋酸丁酯 ,并考察了影响反应的因素。结果表明 :醇酸物质的摩尔比为 1 .6∶ 1、催化剂用量 0 .6g、带水剂甲苯 7m L、反应时间 2 .5 h是最适宜的反应条件 ,其酯化率可达 96.2 %。     

复合固体超强酸SO2-4/TiO2-ZrO2催化合成富马酸二甲酯

合成并表征了新型的复合无机固体超强酸SO2-4/TiO2-ZrO2催化剂,用正交试验方法研究了催化富马酸与甲醇反应合成富马酸二甲酯(DMF)的反应条件,同时考察了催化剂活化温度与催化活性之间的关系.实验结果表明反应物富马酸与甲醇摩尔配比1∶6,催化剂活化温度为550 ℃,催化剂用量2.0%(反应物总质量),反应时间6 h,DMF平均收率91.2%.     

稀土固体超强酸SO42-/TiO2/La3+催化合成马来酸二戊酯

研究了以固体超强酸ＳＯ４＾２－／ＴｉＯ２／Ｌａ＾３＋为催化剂,马来酸和正戊醇为原料合成马来酸二戊酯并考察了影响反应的因素。结果表明,醇酸摩尔比为４．０：１,催化剂用量为１．０ｇ,带水剂甲苯为１５ｍＬ,反应时间为３．０ｈ是最适宜的反应条件,酯化率达９８．８％。     

稀土固体超强酸SO2-4/TiO2/La3+催化合成马来酸二异戊酯

研究了以固体超强酸SO∧2-4/TiO2/La∧3 为催化剂,马来酸和异戊醇为原料合成马来酸二异戊酯,并考察了影响反应的因素。结果表明,醇酸摩尔比为4.0：1,催化剂用量为1.0g（在马来酸用量为0.1mol的情况下）,带水剂甲苯为15mL,反应时间为3.0h是最适宜的反应条件,酯化率达98.2。     

稀土固体超强酸催化合成氯乙酸异丙酯

用稀土固体超强酸催化氯乙酸和异丙醇合成氯乙酸异丙酯,研究了各种因素对酯化率的影响,确定了反应的最佳条件,酸醇摩尔比为1：3,反应时间为5h,催化剂加入量为酸质量的4％,反应温度为回流温度,酯化率可达90．6％。     

S2O82-/Sb2O3-SnO2-La3+固体超强酸催化合成阿司匹林

以水杨酸和乙酸酐为原料,自制的S2O28-/Sb2O3-SnO2-La3+固体超强酸为催化剂合成了阿司匹林。考察了催化剂的制备条件及合成的最佳条件。结果表明,当n(水杨酸)∶n(乙酸酐)=1∶1、反应时间为25 min、反应温度为70℃、催化剂用量为水杨酸的15%,此时阿司匹林的收率可达81.33%。     

固体超强酸SO42-/TiO2催化合成 萜烯-马来酸酐加成物的研究

首次将SO     

固体超强酸SO2-4/TiO2/La3+催化合成氯乙酸乙酯

以稀土固体超强酸SO2-4/TiO2/La3+为催化剂,氯乙酸与乙醇为原料合成氯乙酸乙酯.研究了氯乙酸与乙醇的摩尔比、催化剂用量、环己烷的用量、反应时间诸因素对产品收率的影响.结果表明SO2-4/TiO2/La3+是合成氯乙酸乙酯的良好催化剂,适宜的反应条件如下氯乙酸与乙醇的摩尔比为1∶3.0,催化剂的用量0.8 g,环己烷用量15 mL,反应2.0 h,氯乙酸乙酯的收率可达92.7%.     

SO42-/TiO2固体超强酸催化合成乙酸乙酯

用固体超强酸SO42-/TiO2为催化剂,以乙醇和乙酸为原料合成乙酸乙酯,探讨了催化剂制备条件酯收率的影响,实验结果表明:当用1 mol.L-1H2SO4浸渍TiO212 h,400℃焙烧2 h所得固体超强酸对催化合成乙酸乙酯显示出较高的催化活性。反应温度80℃,催化剂用量为2.0 g,醇酸摩尔比1.8∶1,反应时间为3.0 h时酯的收率最高可达97%。     

稀土复合固体酸SO4^2—／TiO2／La^3＋催化合成马来酸二辛酯

研究了固体超强酸SO4^2-/TiO2/La^3 用于合成马来酸二辛酯，并对硫酸对甲苯磺酸的催化效果比较，考察了Ti/La物质量比，硫酸浓度，焙烧温度对催化剂活性和反应时间对酯化反应的影响，结果表明：当Ti/La物质量比为6：1，浸渍液硫酸浓度为1．8mol/L，在550℃下焙烧时具有最高的催化活性，用于马来酸酐和正辛醇的酯化反应可得无色透明的酯化产物，3h内酯化率达96．9％。     

Synthesis and photoluminescence enhancement of Ca3Sr3(VO4)4:Eu3+ red phosphors by co-doping with La3+

In this study, a series of red-emitting Ca₃Sr₃(VO₄)₄:Eu³⁺ phosphors co-doped with La³⁺ was prepared using the combustion method. The microstructures, morphologies, and photoluminescence properties of the phosphors were investigated. All Ca₃Sr₃(VO₄)₄:Eu³⁺, La³⁺ samples synthesized at temperatures greater than 700 ℃ exhibited the same standard rhombohedral structure of Ca₃Sr₃(VO₄)₄. Furthermore, the Ca₃Sr₃(VO₄)₄:Eu³⁺, La³⁺ phosphor was effectively excited by near-ultraviolet light of 393 nm and blue light of 464 nm. The strong excitation peak at 464 nm corresponded to the ⁷F₀→⁵D₂ electron transition of Eu³⁺. The strong emission peak observed at 619 nm corresponded to the ⁵D₀→⁷F₂ electron transition of Eu³⁺. Co-doping with La³⁺ significantly improved the emission intensity of Ca₃Sr₃(VO₄)₄:Eu³⁺ red phosphors. The optimum luminescence of the phosphor was observed at Eu³⁺ and La³⁺ concentrations of 5% and 6%, respectively. Moreover, co-doping with La³⁺ also improved the fluorescence lifetime and thermal stability of the Ca₃Sr₃(VO₄)₄:Eu³⁺ phosphor. The CIE chromaticity coordinate of Ca₃Sr₃(VO₄)₄:0.05Eu³⁺, 0.06La³⁺ was closer to the NTSC standard for red phosphors than those of other commercial phosphors; moreover, it had greater color purity than that of all the samples tested. The red emission intensity of Ca₃Sr₃(VO₄)₄:0.05Eu³⁺, 0.06La³⁺ at 619 nm was ~1.53 times that of Ca₃Sr₃(VO₄)₄:0.05Eu³⁺ and 2.63 times that of SrS:Eu²⁺. The introduction of charge compensators could further increase the emission intensity of Ca₃Sr₃(VO₄)₄:Eu³⁺, La³⁺ red phosphors. The phosphors synthesized herein are promising red-emitting phosphors for applications in white light-emitting diodes under irradiation by blue chips.     

硅藻土负载La~(3+)/TiO_2光催化剂的制备及其光催化性能

以钛酸四丁酯为前驱体,硅藻土为载体,采用溶胶-凝胶法制备TiO_2/硅藻土负载型光催化剂。以硝酸镧为镧源,采用等体积浸渍-焙烧法制备La~(3+)/TiO_2硅藻土光催化剂。通过XRD和SEM对制备的催化剂进行表征,以亚甲基蓝溶液模拟有机废水,考察n(Ti)∶n(Si)及La3+掺杂量对催化剂光催化性能的影响,结果表明,硅藻土可提高TiO_2分散性,降低TiO_2晶粒尺寸,并抑制其由锐钛矿相向金红石相的转变。在n(Ti)∶n(Si)=1∶1、焙烧温度550℃和La3+掺杂质量分数1%条件下,La~(3+)/TiO_2硅藻土光催化剂的光催化活性较好,紫外光连续照射180 min,亚甲基蓝降解率可达99.9%。     

Color-tunable up-conversion luminescence of Zn(AlxGa1-x)2O4:Yb3+,Tm3+,Er3+ powders

Color-tunable up-conversion powder phosphors Zn(Al_xGa_1-x)₂O₄: Yb³⁺,Tm³⁺,Er³⁺ were synthesized via high temperature solid-state reaction. Also, the morphological and structural characterization, up-conversion luminescent properties were all investigated in this paper. In brief, under the excitation of a 980?nm laser, all powders have same emission peaks containing blue emission at 477?nm (attributed to ¹G₄→³H₆ transition of Tm³⁺ ions), green emission at 526?nm and 549?nm (attributed to ²H_11/2→ ⁴I_15/2 and ⁴S_3/2→⁴I_15/2 transition of Er³⁺ ions respectively), red emission at about 659?nm and 694?nm (attributed to ⁴F_9/2→⁴I_15/2 transition of Er³⁺ ions and ³F₃→³H₆ transition of Tm³⁺ ions, respectively), which are not changed after the doping of Al³⁺ ions. However, the doping of Al³⁺ ions can enhance the up-conversion luminescent intensity and efficiency, while the emission color of as-prepared powder phosphors can be tunable by controlling the doping amount of Al³⁺ ions. Taking Zn(Al_0.5Ga_0.5)₂O₄:Yb,Tm,Er as the cut-off value, the emissions have clear blue-shift firstly and then show obvious red-shift with the increasing doping of Al³⁺ ions. Stated thus, pink emission in ZnAl₂O₄:Yb,Tm,Er, purplish pink emission in ZnGa₂O₄:Yb,Tm,Er and Zn(Al_0.9Ga_0.1)₂O₄:Yb,Tm,Er, purple emission in Zn(Al_0.1Ga_0.9)₂O₄:Yb,Tm,Er and Zn(Al_0.3Ga_0.7)₂O₄:Yb,Tm,Er, purplish blue emission in Zn(Al_0.7Ga_0.3)₂O₄:Yb,Tm,Er, blue emission in Zn(Al_0.5Ga_0.5)₂O₄:Yb,Tm,Er can be observed, which confirm the potential applications of as-prepared Zn(Al_xGa_1-x)₂O₄:Yb³⁺,Tm³⁺,Er³⁺ powder phosphors in luminous paint, infrared detection and so on.     

Fe^3＋、Ce^4＋掺杂改性对SO4^2-/TiO2固体超强酸催化尿囊素催化性能的研究

采用液相浸渍的方法对SO4^2-/TiO2进行Fe、Ce双元素掺杂改性,以合成尿囊素产率大小为判断标准,考察通过掺杂改性后的催化剂催化性能,优化制备催化剂的工艺条件。结果表明,当Ce^4＋：TiO2=0.06%、Fe^3＋：TiO2=0.2%,浸渍溶液是硫酸,浸渍浓度为0.66 mol·L^-1,浸渍溶液的体积为15 mL/g,浸渍时间为20 h,焙烧温度540℃,焙烧时间3.4 h,尿囊素的产率最高,催化活性最佳,可重复使用4次以上,重复实验得到的尿囊素平均产率基本维持在65%左右。制得的尿囊素进行产品鉴定,符合工业标准。     

Synthesis of CaTiO3 and CaTiO3/TiO2 nanoparticulate compounds through Ca2+/TiO2 colloidal sols: Structural and photocatalytic characterization

CaTiO₃ and CaTiO₃/TiO₂ nanocompounds have been synthesized through a colloidal sol-gel route using Ca²⁺/TiO₂ nanoparticulate sols. The peptization time was determined so that as higher is the Ca²⁺ concentration, shorter is the peptization time. The obtained cryogels from the respective sols were calcined at different temperatures (300–900 °C) and the structural and morphological changes were characterized mainly by X-ray diffraction and transmission electron microscopy. In all cases, the formation of the CaTiO₃ phase was observed after calcination at temperatures as low as 500 °C. Mesoporous cryogels with nanoparticles with sizes below 50 nm were obtained and their photocatalytic activity changes as a function of the calcination temperature and the applied wavelength were determined. Quantum yield values revealed that either CaTiO₃ or the CaTiO₃/TiO₂ (0.4 M ratio) compound can be chosen as the most efficient photocatalyst at higher calcination temperatures and longer wavelengths, while TiO₂ is more effective at low calcination temperatures and shorter wavelengths.     

Lower power dependent upconversion multicolor tunable properties in TiO2:Yb3+/Er3+/ (Tm3+)

Multicolor tunable upconversion luminescence materials could be applied to polychromatic LED and anti-counterfeit due to their superiority in abundant color and security feature. However, the harsh terms to achieve emission tuning associated with the drawbacks, including changing the concentration or types of doping ions, higher temperature, and higher excitation power, limit the range of its application. In this paper, a convenient and versatile approach for multicolor-emitting is realized via simply lower power modulating in TiO₂:Yb³⁺/ Er³⁺ and TiO₂: Yb³⁺/Er³⁺/Tm³⁺. The emission color is tuned from pink to yellowish green in TiO₂:Yb³⁺/ Er³⁺ and tuned from white to yellowish green in TiO₂: Yb³⁺/Er³⁺/Tm³⁺. It's found that there is no apparent temperature variation at lower power. Meanwhile, the mechanism of the emission and the multicolor tunability is discussed.     

光照对Sr4Al14O25：Eu^2＋，Dy^3＋／TiO2-xNx复合材料光催化性能的影响

采用溶胶-凝胶法制备出Sr4Al14O25：Eu^2＋,Dy^3＋／TiO2-xNx复合材料。该复合材料对甲基橙具有较高的光催化效果,复合材料经紫外激发后,其光催化效果高于没有经紫外激发的复合材料的光催化效果,而且明显高于Sr4Al14O25：Eu^2＋,Dy^3＋／TiO2-xNx光照激发后光催化效率之和,同时讨论了Sr4Al14O25：Eu^2＋,Dy^3＋／TiO2-xNx复合材料的光催化机理。     

固体超强酸SO^2—4／TiO2催化合成尿囊素的研究

用固体超强酸SO42/TiO2为催化剂,以尿素和乙醛酸为原料合成了尿囊素。得到最佳条件为TiO2在1mo1·L-1H2SO4溶液中浸渍12h,再在600℃焙烧3h;尿素与乙醛酸摩尔比3.51,催化剂9％,时间3h,温度72℃～75℃,产率达57.4％。     

Effect of isovalent substitution of La3+ in Ca-doped LaNbO4 on the thermal and electrical properties

The effect of the equimolar substitution of lanthanum in Ca-doped LaNbO₄ on the functionality of (La_0.5Ln_0.5)_0.99Сa_0.01NbO_4–δ (where Ln?=?La, Nd and Sm) is investigated in the present work. Highly dense, single-phase and of microstructurally quality ceramic samples are synthesized, using a solid state reaction method. The relation between Ln³⁺ ionic radii with thermal and electrical properties is successfully revealed. It is found that the partial substitution with other lanthanides can be considered as a promising tool to suppress thermal expansion differences between low- and high-temperature modifications of lanthanum niobates; however, at the same time, the ionic conductivity decreases, which requires searching the trade-off for the optimal composition identification.