WO2006131032A1

WO2006131032A1 - A method for preparing nano particles of spinel with high specific surface area through lamellar precursors

Info

Publication number: WO2006131032A1
Application number: PCT/CN2005/001382
Authority: WO
Inventors: Xue Duan; Feng Li; Lu Zou
Original assignee: Beijing University Of Chemical Technology
Priority date: 2005-06-08
Filing date: 2005-09-01
Publication date: 2006-12-14
Also published as: CN1693185A; CN100427380C

Abstract

The invention provides a method for preparing nano particles of spinel with high specific surface area through lamellar precursors, including preparing lamellar compounds LDHs of ZnMIII first, calcining the lamellar precursors under high temperature to obtain nano particles of ZnMIII2O4 spinel and high dispersed ZnO, and then removing the high dispersed ZnO by concentrated alkali solution to obtain nano particles material of ZnMIII2O4 spinel with high specific surface area basing on the characteristic of amphoteric oxide of ZnO. The nano particles of ZnMIII2O4 spinel obtained by the method have characteristics of uniform compositon and high specific surface area, etc. owing to the high dispersing, the high reactivity and small particle sizes of metal elements in the lamellar precursors. Furthermore, mixing and grinding processes are not needed before calcining and the calcining temperature may also be highly reduced so as to simplify the production process, shorten the production cycle, save equipment investment and economize energy consumption.

Description

一种由层状前驱体法制备高比表面积纳米尖晶石的方法 Method for preparing high specific surface area nano spinel by layered precursor method

技术领域 Technical field

本发明属于纳米尖晶石制备技术领域，特别是提供了一种由层状前驱体法制备高比表面积纳米 ZnM^m ₂0₄尖晶石的方法。背景技术 The invention belongs to the technical field of nano spinel preparation, and in particular provides a method for preparing high specific surface area nano ZnM ^m ₂ 0 ₄ spinel by a layered precursor method. Background technique

尖.晶石型复合氧化物 ZnM¹'¹^是一类 ί艮有前途的无机非金属材料，具有一系列良好的特性而被广泛应用于高温材料、半导体光电材料、传感器以及催化剂和催化剂载体等。目前，制备该类尖晶石材料的方法主要是传统的陶瓷法，但由于高温煅烧时产物容易团聚，整体均一性差，比表面积很小，严重地影响了该类材料的应用。而纳米材料通常具有较大的比表面积，且其本身具有量子尺寸效应、表面效应、体积效应和宏观量子隧道效应等，在热、磁、光.、敏感特性和表面稳定性等表现出不同于一般材料的许多特有性能，因此制备具有纳米尺寸的 ZnM^m ₂0₄尖晶石有着十分重要的意义，可以大大拓展该类材料的应用。 The spar-type composite oxide ZnM ¹ ' ¹ ^ is a kind of promising inorganic non-metallic material with a series of good properties and is widely used in high temperature materials, semiconductor optoelectronic materials, sensors, and catalysts and catalyst carriers. Wait. At present, the method for preparing such a spinel material is mainly a conventional ceramic method, but the product is easily agglomerated due to high temperature calcination, the overall uniformity is poor, and the specific surface area is small, which seriously affects the application of the material. Nanomaterials usually have a large specific surface area, and they have quantum size effects, surface effects, volume effects, and macroscopic quantum tunneling effects. They are different in heat, magnetism, light, sensitivity, and surface stability. Many unique properties of general materials, so the preparation of nano-sized ZnM ^m ₂ 0 ₄ spinel is of great significance, can greatly expand the application of such materials.

为了克服传统的陶瓷法固有的缺陷，目前如文献 S. Mathur, M. Vei th, M. Haas, A. Shen, N. Lecerf, V. Huch, S. Hufner, R. Haberkorn, H. P. Beck, M， Ji lavi, J. Am. Cream. Soc, , 84, 1921 (2001)和文献 M. A, Valenzulela, P. Boshch, G. Agui lar-Rios, A. Montoya and I. Schif ter, J. Sol-Gel Sci. Tec nol . , 8, 107 (1997) 通过溶胶-凝胶法在相对较低的温度下制备出了具有高比表面积的纳米 ZriAlA, 但由于采用了昂贵的金属醇盐作为反应起始物，所以整个制备过程的成本高昂；且煅烧过程中会释放出醇类等有机物，从而使得煅烧过程较为危险，需要相应的保护措施，对环境也不友好。发明内容 In order to overcome the inherent defects of the traditional ceramic method, it is currently known as S. Mathur, M. Vei th, M. Haas, A. Shen, N. Lecerf, V. Huch, S. Hufner, R. Haberkorn, HP Beck, M , Ji lavi, J. Am. Cream. Soc, , 84, 1921 (2001) and the literature M. A, Valenzulela, P. Boshch, G. Agui lar-Rios, A. Montoya and I. Schif ter, J. Sol -Gel Sci. Tec nol., 8, 107 (1997) Preparation of nano ZriAlA with high specific surface area by sol-gel method at relatively low temperature, but due to the use of expensive metal alkoxides as reaction The starting material, so the entire preparation process is costly; and the organic matter such as alcohol is released during the calcination process, so that the calcination process is dangerous, requires corresponding protective measures, and is not environmentally friendly. Summary of the invention

本发明的目的在于提供一种具有高比表面积的纳米 ZnM^m ₂0₄尖晶石的制备方法， M¹¹¹为三价金属离子 (Α 、 Cr³\ Ga³⁺和 In³⁺) , 解决了传统的陶瓷方法中反应不易完全、产物组分均一性差和比表面积小等问题；并且克服了在溶胶 -凝胶法中存在的制备成本高昂、煅烧过程危险和环境不友好等不利因素。 ' The object of the present invention is to provide a method for preparing a nano-ZnM ^m ₂ 0 ₄ spinel having a high specific surface area, and M ¹¹¹ is a trivalent metal ion (Α, Cr ³ \ Ga ³⁺ and In ³⁺ ), which solves In the conventional ceramic method, the reaction is not complete, the product composition is poor in uniformity and the specific surface area is small, and the disadvantages such as high preparation cost, calcination process and environmental unfriendly in the sol-gel method are overcome. '

本发明的高比表面积的纳米 ZnM^m ₂0₄尖晶石是通过先制备整体均一、化学组成和结构在微观上可调变、活性高的单一化合物作为前体原料，再经焙烧、提纯的方法制备的。 The high specific surface area nano ZnM ^m ₂ ₄ spinel of the present invention is prepared by first preparing a single compound which is uniform in overall chemical composition and structure and has high activity and high activity as a precursor material, and then calcined and purified. Method prepared.

层状双金属氢氧化物 (LDHs)是一类具有层状结构的新型纳米无机功能材料，其化学组成可以表示为 [M²V_XM³⁺ _X (OH) ₂〗 ^x+ (Aⁿ- ) _x/n - mH₂0, 其中 M²⁺为 Mg²⁺、 Ni²⁺、 Co²⁺、 Zn²⁺、 Cu²⁺等二价金属阳离子; M³⁺为 Α 、 Cr³⁺、 Ga³⁺、 In³⁺、 Fe³⁺、 Sc³⁺等三价金属阳离子; Aⁿ—为阴离子，如 CO/—、 N0₃—、 CI一、 OH -、 SO 、 P0₄ ³—、 C₆H, (COO) ₂ ^2_等无机、有机离子以及络合离子， X值在 0. 2 - 0. 33之间。在 LDHs 晶体结构中，由于受晶格能最低效应及其晶格定位效应的影响，使得金属离子在层板上以一定方式均勾分布，即在层板上每一个微小的结构单元中 , 其化学组成和结构不变。由于 LDHs的这种化学组成和 ^敫观结构上的可调控性和整体均勾性，本身又是二维纳米材料，所以这种特殊结构和组成的材料是合成组分均一的纳米尖晶石类材料的良好前体。但由于 LDHs中二、三价金属离子化学计量比（ M²⁺/M³⁺摩尔比 =2 ~ 4 )远大于尖晶石中二、三价金属离子化学计量比（M²7M³⁺摩尔比 =0. 5 ) , 因此， LDHs直接焙烧产物为尖晶石与分散性良好的二价金属氧化物的混合物。 Layered double hydroxides (LDHs) are a class of novel nano-inorganic functional materials with a layered structure. The chemical composition can be expressed as [M ² V _X M ³⁺ _X (OH) ₂ 〗 ^x+ (A ⁿ - ) _x/n - mH ₂ 0, wherein M ²⁺ is a divalent metal cation such as Mg ²⁺ , Ni ²⁺ , Co ²⁺ , Zn ²⁺ , Cu ²⁺ ; M ³⁺ is Α , Cr ³⁺ , Ga ³ Trivalent metal cations such as ⁺ , In ³⁺ , Fe ³⁺ , Sc ³⁺ ; A ⁿ — is an anion such as CO/—, N0 ₃ —, CI—, OH—, SO, P0 ₄ ³ —, C ₆ H ₅ ^之间之间。 The (COO) ₂ ^2_ and other inorganic, organic ions and complex ions, X value between 0. 2 - 0. In the crystal structure of LDHs, due to the influence of the minimum lattice energy and its lattice positioning effect, the metal ions are uniformly distributed on the laminate in a certain way, that is, in each tiny structural unit on the laminate, The chemical composition and structure are unchanged. Due to the chemical composition of the LDHs and the controllability and overall homogeneity of the structure, it is itself a two-dimensional nanomaterial. Therefore, the material of this special structure and composition is a nano-spinel with uniform composition. A good precursor for the class of materials. However, the stoichiometric ratio of the divalent and trivalent metal ions in the LDHs (M ²⁺ /M ³⁺ molar ratio = 2 ~ 4 ) is much larger than the stoichiometric ratio of the divalent and trivalent metal ions in the spinel (M ² 7M ³⁺ moles) Ratio = 0.5). Therefore, the direct calcined product of LDHs is a mixture of spinel and a divalent metal oxide having good dispersibility.

针对这一现状，本发明提出将 Zn²⁺引入水滑石层板，通过调控层板组成，使 LDHs焙烧产物为 ZnM^m ₂0₄尖晶石和高分散 ZnO两相的混合物。再利用 ZnO 的两性性质，用碱溶解将之去除，从而得到组分单一的高比表面积纳米 ZnM^m ₂0₄尖晶石。在此，高分散 ZnO主要起到了分散和阻隔的效果。即防止生成的纳米 ZnM^m ₂0₄尖晶石粒子的进一步长大和粒子之间团聚现象的发生。该高比表面积的纳米 ZnM^m ₂0₄尖晶石的制备方法为： In view of this situation, the present invention proposes to introduce Zn ²⁺ into a hydrotalcite laminate, and to control the laminate composition, the LDHs calcined product is a mixture of ZnM ^m ₂ 0 ₄ spinel and highly dispersed ZnO two phases. Reuse amphipathic nature of ZnO, they will be removed by alkali dissolution to obtain a single component of high surface area nano ZnM ^m ₂ 0 ₄ spinel. Here, the highly dispersed ZnO mainly serves as a dispersion and barrier. Prevent The generated nano-ZnM ^m ₂ 0 ₄ spinel particles are further grown and agglomeration occurs between the particles. The preparation method of the high specific surface area nano ZnM ^m ₂ 0 ₄ spinel is:

a. 按照 LDHs 中各离子的摩尔关系配制含有二价金属离子 Zn²⁺和三价 M³⁺离子的混合盐溶液，其中各种金属离子的摩尔浓度分别为 Zn²⁺: 0.6-1.5 摩尔浓度， M³⁺: 0.15 0.6摩尔浓度；用氢氧化钠和可溶性无机钠盐配制混合碱溶液，其中氢氧化钠浓度为 1.2 ~ 2. S摩尔浓度，可溶性无机钠盐浓度为 0.3~1.0摩尔浓度。 a mixed salt solution containing a divalent metal ion Zn ²⁺ and a trivalent M ³⁺ ion according to the molar relationship of each ion in the LDHs, wherein the molar concentration of each metal ion is Zn ²⁺ : 0.6-1.5 molar concentration , M ³⁺ : 0.15 0.6 molar concentration; a mixed alkali solution is prepared by using sodium hydroxide and a soluble inorganic sodium salt, wherein the sodium hydroxide concentration is 1.2 to 2. S molar concentration, and the soluble inorganic sodium salt concentration is 0.3 to 1.0 molar concentration.

b. 采用成核 /晶化隔离法或者双滴法（ 11值控制在 6~12之间），制备水滑石层状前体，晶化温度 40~95°C, 晶化时间 2 ~ 30小时，经过滤，洗涤，干燥，获得 Zn- M^m层状双羟基氢氧化物水滑石 LDHs。 b. Using nucleation/crystallization separation method or double-drop method (11-value control between 6~12), prepare hydrotalcite layered precursor, crystallization temperature 40~95°C, crystallization time 2~30 hours After filtration, washing and drying, Zn-M ^m layered bishydroxyhydroxide hydrotalcite LDHs were obtained.

c，将上述 LDHs置于马弗炉中，室温加热焙烧，升温速率 2~15°C/分钟，温度升至400 ~ 1000°(并保温2~1()小时，焙烧产物自然冷却至室温得到纳米 ZnM^m ₂0₄尖晶石与高分散的 ZnO; c, the above LDHs are placed in a muffle furnace, calcined at room temperature, the heating rate is 2~15 ° C / min, the temperature is raised to 400 ~ 1000 ° (and kept for 2 ~ 1 () hours, the calcined product is naturally cooled to room temperature. Nano ZnM ^m ₂ 0 ₄ spinel and highly dispersed ZnO;

d. 将纳米 ZnM^m ₂0₄尖晶石与高分散 ZnO的混合物用浓度为 5~15摩尔浓度的碱溶液在 25 ~ 35°C处理 24 - 96小时，然后用去离子水洗涤到中性，除去高分散 ZnO, 得到高比表面积的纳米 ΖηΜ^πιΛ尖晶石。 d. Mix a mixture of nano-ZnM ^m ₂ 0 ₄ spinel and highly dispersed ZnO with an alkali solution having a concentration of 5-15 mol at 25-35 ° C for 24-96 hours, then wash with neutralized water to neutral The highly dispersed ZnO is removed to obtain a nano-ΖηΜ ^πι Λ spinel having a high specific surface area.

本发明步骤 a中，盐混合溶液中的的酸根离子为 Cl_、 N0₃—或 SO 中的 1 ~ 2种；其中 M³⁺为 Al³⁺、 Cr³⁺、 Ga³⁺或 In³⁺中的 1 ~ 3种；可溶性钠盐为碳酸纳、硫酸钠或氯化钠中的任意一种。 In the step a of the present invention, the acid ions in the salt mixed solution are Cl_, N0 ₃ - or 1-2 in the SO; wherein M ³⁺ is Al ³⁺ , Cr ³⁺ , Ga ³⁺ or In ³⁺ 1 to 3; the soluble sodium salt is any one of sodium carbonate, sodium sulfate or sodium chloride.

本发明步骤 d中，碱溶液所用减为 NaOH或 K0H。 In the step d of the present invention, the alkali solution is reduced to NaOH or K0H.

本发明具有如下显著效果： The present invention has the following remarkable effects:

1, 制备纳米 ZnM^m ₂0₄尖晶石所用的层状前体具有结构均一、组成和结构可调变、活性高等特点，不存在原料混合不均勾和活性低的缺点； 1. The layered precursor used in the preparation of nano-ZnM ^m ₂ 0 ₄ spinel has the characteristics of uniform structure, adjustable composition and structure, high activity, and the like, and has the disadvantages of uneven mixing of raw materials and low activity;

2. 采用本发明的方法制备出的纳米 ZnM^m ₂0₄尖晶石具有组分均一、粒度小（以 X射线衍射数据计算和透射电境观察表明，平均晶粒尺寸在 5nm ~2. The nano-ZnM ^m ₂ 0 ₄ spinel prepared by the method of the invention has uniform composition and small particle size (calculated by X-ray diffraction data and observed by transmission electrons, the average grain size is 5 nm ~

80nm之间）和高比表面积（~ 263mVg), 等特点; 3. 由于不需要对原料进行混磨工艺，且煅烧温度可以大大降低，从而可筒化生产工艺，缩短生产周期，节省设备投资，大幅度节约生产能耗。具体实施方式实施例 1 80nm) and high specific surface area (~ 263mVg), etc.; 3. Since the raw material is not required to be mixed and the calcination temperature can be greatly reduced, the production process can be shortened, the production cycle can be shortened, equipment investment can be saved, and production energy consumption can be greatly saved. DETAILED DESCRIPTION OF THE INVENTION Embodiment 1

用去离子水配置 ZnCl₂和 A1 ( ₃)₃的混合盐溶液 200毫升，使溶液中金属离子的浓度分别 Zn²⁺: 1.2摩尔浓度， Al³⁺: 0.4摩尔浓度；再用氢氧化钠和无水碳酸钠配制混合碱溶液 200毫升，其中氢氧化钠浓度为 2.6摩尔浓度，无水碳酸钠浓度为 0.8摩尔浓度。釆用成核 /晶化隔离法将上述混合盐溶液和混合碱溶液迅速于全返混液膜反应器中混合，剧烈循环搅拌两分钟，然后将浆液置于三口瓶中在 90°C水浴中下晶化 6h, 过滤，洗涤，干燥，即得_∑1^1- C0₃- LDHs。将上述 LDHs放于马弗炉中，室温加热焙烧，升温速率 10°C/分钟，温度升至 5G0°C：、 60Q°C 70Q°C和 800°C并保温 5h，焙烧产物自然冷却至室温得到 ΖηΑΙΛ尖晶石与 ΖηΟ的混合物，然后用 10摩尔浓度的浓 NaOH溶液处理 48h除去过量 ΖηΟ。所得 ΖηΑ1₂0₄尖晶石在 50(TC 600°C 700°C和 800°C时的晶粒尺寸分别为 8nm 9 10nm和 15nm; 比表面积分別为 263m²/g 206m²/g 181m²/g和 73m²/g 实施例 2 Dissolve 200 ml of mixed salt solution of ZnCl ₂ and A1 ( ₃ ) ₃ with deionized water to make the concentration of metal ions in the solution Zn ²⁺ : 1.2 molar, Al ³⁺ : 0.4 molar; 200 ml of a mixed alkali solution was prepared with anhydrous sodium carbonate, wherein the sodium hydroxide concentration was 2.6 molar, and the anhydrous sodium carbonate concentration was 0.8 molar. The above mixed salt solution and mixed alkali solution were quickly mixed in the full back-mixed membrane reactor by nucleation/crystallization separation method, vigorously stirred for two minutes, and then the slurry was placed in a three-necked flask in a 90 ° C water bath. Crystallization for 6 h, filtration, washing, and drying, that is, _∑1^1-C0 ₃ - LDHs. The above LDHs were placed in a muffle furnace, and calcined at room temperature, the heating rate was 10 ° C / min, the temperature was raised to 5 G0 ° C:, 60 Q ° C 70 Q ° C and 800 ° C and kept for 5 h, and the calcined product was naturally cooled to room temperature. A mixture of ΖηΑΙΛ spinel and ΖηΟ was obtained, and then treated with a 10 molar concentrated NaOH solution for 48 hours to remove excess ΖηΟ. The resulting ΖηΑ1 ₂ 0 ₄ spinel grain size at 50 (TC 600 ° C 700 ° C to 800 ° C and are 8nm 9 10nm and 15nm; specific surface area of ^{^{263m 2 / g 206m 2 / g}} 181m 2 respectively / g and 73 m ² /g Example 2

用 ZnS0₄ A1₂(S0₄)₃和 In₂(S0₄) &制无机盐混合溶液 100毫升，其中金属离子的摩尔浓度分别为 Zn²⁺: 0.8摩尔浓度， Al³⁺: 0.2摩尔浓度， In³⁺: 0.2摩尔浓度；另配制由 1.25摩尔浓度的氢氧化钠和 0.5摩尔浓度的硫酸钠组成的混合碱溶液 250毫升，在四口瓶中加入 50ml去离子水后，同时滴加混合盐溶液和碱溶液（双滴法），滴加过程保持反应液的 pH值为 7，滴加完毕后（无机盐混合溶液全部滴完，碱溶液用量由维持体系最终 pH值确定），反应液在 50°C下晶化 24 小时，反应液抽滤后，洗涤，干燥，即得 ZnAl In- S0₄- LDHs。将上述 LDHs放于马弗炉中，室温加热焙烧，升温速率 5 °C /分钟，温度升至 600°C、 800°C和 l OQfTC并保温 3h, 焙烧产物自然冷却至室温得到 21^11110₄尖晶石与 ZnO的混合物，然后用 5摩尔浓度的浓 K0H 溶液处理 36h除去过量 ZnO。所得 21^11110₄尖晶石在 600°C、 800°C和 1000°C 时的晶粒尺寸分别为 16nm、 35舰和 63nm; 比表面积分别为 135m²/g 47m²/g 和 17m²/g。实施例 3 100 ml of a mixed solution of ZnS0 ₄ A1 ₂ (S0 ₄ ) ₃ and In ₂ (S0 ₄ ) & an inorganic salt, wherein the molar concentration of metal ions is Zn ²⁺ : 0.8 molar, Al ³⁺ : 0.2 molar, In ³⁺ : 0.2 molar concentration; 250 ml of a mixed alkali solution consisting of 1.25 molar sodium hydroxide and 0.5 molar sodium sulfate was prepared, and 50 ml of deionized water was added to the four-necked flask, and mixed salt was added dropwise. Solution and alkali solution (double drop method), the pH of the reaction solution is maintained at the dropwise addition process, after the addition is completed (the inorganic salt mixed solution is completely dripped, the amount of the alkali solution is determined by maintaining the final pH of the system), and the reaction solution is Crystallization at 50 ° C for 24 hours, the reaction solution is filtered, washed, and dried. ZnAl In- S0 ₄ - LDHs. The above LDHs were placed in a muffle furnace, calcined at room temperature, the heating rate was 5 ° C / min, the temperature was raised to 600 ° C, 800 ° C and 1 OQfTC and kept for 3 h, and the calcined product was naturally cooled to room temperature to obtain 21 ^ 11110 ₄ A mixture of spinel and ZnO was then treated with a 5 molar solution of concentrated K0H for 36 h to remove excess ZnO. The resulting spinel ₁₁₁ 104 21 ^ 600 ° C, the grain size at 800 ° C and 1000 ° C respectively 16nm, 35 ships and 63nm; specific surface area of 135m ^² / g 47m ² / g, respectively, and 17m ² / g. Example 3

用去离子水配置 Zn (N0₃) ₂和 Cr (N0₃) ₃的混合盐溶液 20 G毫升，使溶液中金属离子的浓度分别 Zn²⁺: 0. 8摩尔浓度， Cr³⁺: 0. 3摩尔浓度；再用氢氧化钠和无水碳酸钠配制混合碱溶液 200毫升，其中氢氧化钠浓度为 1. 8摩尔浓度，无水碳酸钠浓度为 0. 6摩尔浓度。采用成核 /晶化隔离法将上述混合盐溶液和混合碱溶液迅速于全返混液膜反应器中混合，剧烈循环搅拌两分钟，然后将浆液置于三口瓶中在 65 °C水浴中下晶化 12h, 过滤，洗涤，干燥，即得 ZnCr- C0₃- LDHs。将上述 LDHs放于马弗炉中，室温加热焙烧，升温速率 3 °C /分钟，温度升至 700 °C并保温 3h, 焙烧产物自然冷却至室温得到！！尖晶石与 ZnO的混合物，然后用 15摩尔浓度的浓 NaOH溶液处理 84h 除去过量 Zn0。所得 ZnCr₂0₄尖晶石的晶粒尺寸为 16腿，比表面积为 40m²/g。实施例 4 The mixed salt solution of Zn(N0 ₃ ) ₂ and Cr (N0 ₃ ) ₃ was deionized water to a concentration of 20 g of the metal ion so that the concentration of the metal ions in the solution was Zn ²⁺ : 0.8 mol, Cr ³⁺ : 0. 6摩尔浓度。 The molar concentration of sodium carbonate is 0. 6 molar concentration. The mixed salt solution and the mixed alkali solution were quickly mixed in the full back-mixed membrane reactor by nucleation/crystallization separation method, vigorously stirred for two minutes, and then the slurry was placed in a three-necked flask to be crystallized in a 65 ° C water bath. 12h, filtered, washed, dried, that is, ZnCr-C0 ₃ - LDHs. The above LDHs were placed in a muffle furnace, and calcined at room temperature, the heating rate was 3 ° C / min, the temperature was raised to 700 ° C and kept for 3 h, and the calcined product was naturally cooled to room temperature to obtain! ! A mixture of spinel and ZnO was then treated with a 15 molar concentrated NaOH solution for 84 h to remove excess Zn0. The resulting ZnCr ₂ 0 ₄ spinel grain size of the leg 16, a specific surface area of 40m ² / g. Example 4

用 ZnCl₂和 GaCl₃配制无机盐混合溶液 100毫升，其中金属离子的摩尔浓度分别为 Zn²⁺: 0. 9摩尔浓度， Ga³⁺: 0. 3摩尔浓度；另配制由 2. 0摩尔浓度的氢氧化钠和 0. 3摩尔浓度的氯化钠组成的混合碱溶液 150毫升，在四口瓶中加入 50ml去离子水后，同时滴加混合盐溶液和碱溶液（双滴法），滴加过程保持反应液的 pH值为 11. 5 , 滴加完毕后（无机盐混合溶液全部滴完，碱溶液用量由维持体系最终 pH值确定） , 反应液在 80 °C下晶化 24小时，反应液抽滤后，洗涤，干燥，即得 ZnGa- - LDHs。将上述 LDHs放于马弗炉中，室温加热焙烧，升温速率 15°C/分钟，温度升至 900°C并保温 10h，焙烧产物自然冷却至室温得到 ZnGaA尖晶石与 ZnO 的混合物，然后用 10 摩尔浓度的浓 K0H溶液处理 24h除去过量 Zn0。所得 ZnGa₂0₄尖晶石的晶粒尺寸为 25nm，比表面积为 13m²/g。 GaCl ₃ with ZnCl ₂ and 100 ml of a mixed formulation inorganic salt, wherein the molar concentration of the metal ions are Zn ^2+: 0. 9 molar concentration, Ga ^3+: 0. 3 molar concentration; the other is prepared from 2.0 molar concentration 150 ml of a mixed alkali solution consisting of sodium hydroxide and 0.3 mol of sodium chloride, and adding 50 ml of deionized water to a four-necked bottle, while adding a mixed salt solution and an alkali solution (double drop method), dropping The addition process maintains the pH of the reaction solution at 11.5. After the addition is completed (the inorganic salt mixed solution is completely dripped, the amount of the alkali solution is determined by maintaining the final pH of the system), and the reaction solution is crystallized at 80 ° C for 24 hours. After the reaction solution was suction filtered, washed and dried to obtain ZnGa- - LDHs. Put the above LDHs on the horse In the furnace, calcination is carried out at room temperature, the heating rate is 15 ° C / min, the temperature is raised to 900 ° C and kept for 10 h, and the calcined product is naturally cooled to room temperature to obtain a mixture of ZnGaA spinel and ZnO, and then 10 K of concentrated K0H is used. The solution was treated for 24 h to remove excess Zn0. The resulting ZnGa ₂ 0 ₄ spinel grain size of 25nm, specific surface area of 13m ² / g.

Claims

权利要求书 Claim

1. 一种由层状前驱体法制备高比表面积纳米 ZnM^m ₂0₄尖晶石的方法，其特征在于：将 Zn²⁺引入水滑石层板，通过调控层板组成，使 LDHs焙烧产物为 ZnM^m ₂0₄尖晶石和高分散 ZnO两相的混合物；再利用 ZnO的两性性质，用碱溶解将之去除，从而得到组分单一的高比表面积纳米 ZnM^m ₂0₄尖晶石。 A method for preparing a high specific surface area nano-ZnM ^m ₂ 0 ₄ spinel by a layered precursor method, characterized in that: Zn ^{2+ is} introduced into a hydrotalcite layer, and the LDHs calcined product is controlled by controlling the composition of the laminate mixture ZnM ^m ₂ 0 ₄ spinel phases and two highly dispersed ZnO; reuse amphoteric properties of ZnO, they will be removed by alkali dissolution to obtain a single component of high surface area nano ZnM ^m ₂ 0 ₄ spinel.

2、根据权利要求 1所述的方法，其特征在于：具体工艺步骤为： a. 按照 LDHs 中各离子的摩尔关系配制含有二价金属离子 Ζιι²⁺和三价 M³⁺离子的混合盐溶液，其中各种金属离子的摩尔浓度分别为 Ζιι²⁺: 0.6-1.5 摩尔浓度， M³⁺: 0.15 ~ 0.6摩尔浓度；用氢氧化钠和可溶性无机钠盐配制混合碱溶液，其中氢氧化钠浓度为 1.2 ~ 2.8摩尔浓度，可溶性无机钠盐浓度为 0.3~1.0摩尔浓度; 2. The method according to claim 1, wherein the specific process steps are: a. preparing a mixed salt solution containing a divalent metal ion Ζι ²⁺ and a trivalent M ³⁺ ion according to a molar relationship of ions in the LDHs. , wherein the molar concentration of each metal ion is Ζι ²⁺ : 0.6-1.5 molar concentration, M ³⁺ : 0.15 ~ 0.6 molar concentration; using sodium hydroxide and soluble inorganic sodium salt to prepare mixed alkali solution, wherein sodium hydroxide concentration The concentration of the soluble inorganic sodium salt is from 0.3 to 1.0 molar, from 1.2 to 2.8 molar;

b. 采用成核 /晶化隔离法或者双滴法， pH值控制在 6~12之间，制备水滑石层状前体，晶化温度 40~95°C, 晶化时间 2~ 30小时，经过滤，洗涤，干燥，获得 Zn- M¹¹¹层状双羟基氢氧化物水滑石 LDHs; b. Using nucleation/crystallization separation method or double-drop method, the pH value is controlled between 6 and 12, and the hydrotalcite layered precursor is prepared, the crystallization temperature is 40-95 ° C, and the crystallization time is 2 to 30 hours. After filtering, washing and drying, obtaining Zn-M ¹¹¹ layered bishydroxyhydroxide hydrotalcite LDHs;

c. 将上述 LMs置于马弗炉中，.室温加热焙烧，升温速率 2~15°C/分钟，温度升至 400 ~100()°C并保温 2~10小时，焙烧产物自然冷却至室温得到纳米 ZnM^mA尖晶石与高分散的 ZnO; c. The above LMs are placed in a muffle furnace, heated at room temperature for heating, the heating rate is 2-15 ° C / min, the temperature is raised to 400 ~ 100 () ° C and kept for 2 to 10 hours, the calcined product is naturally cooled to room temperature. Obtaining nano ZnM ^m A spinel and highly dispersed ZnO;

d. 将纳米 ZnM^m ₂0₄尖晶石与高分散 ZnO的混合物用浓度为 5 ~ 15摩尔浓度的碱溶液在 25~35°C处理 24~96小时，然后用去离子水洗涤到中性，除去高分散 ZnO, 得到高比表面积的纳米 ZnM^m ₂0₄尖晶石。 d. Mix a mixture of nano-ZnM ^m ₂ 0 ₄ spinel and highly dispersed ZnO with an alkali solution having a concentration of 5 to 15 molars at 25 to 35 ° C for 24 to 96 hours, and then wash with neutralized water to neutrality. removing highly dispersed ZnO, high surface area nano ZnM ^m ₂ 0 ₄ spinel.

3. 根据权利要求 1或 2所述的方法，其特征在于：步骤 a中，盐混合溶液中的酸根离子为 C1'―、 ₃或 S0 中的 1 ~ 2种；其中 M³⁺为 Al³⁺、 Cr³⁺、 Ga³⁺ 或 In³⁺中的 1 ~ 3种；可溶性钠盐为碳酸纳、硫酸钠或氯化钠中的任意一种。 The method according to claim 1 or 2, wherein in the step a, the acid ions in the salt mixed solution are 1 to 2 of C1'-, ₃ or S0; wherein M ³⁺ is Al ³ 1 to 3 of ⁺ , Cr ³⁺ , Ga ³⁺ or In ³⁺ ; the soluble sodium salt is any one of sodium carbonate, sodium sulfate or sodium chloride.

4、根据权利要求 1或 2所述的方法，其特征在于：步骤 d中，碱溶液所用碱为 NaOH或 K0H。 4. The method according to claim 1 or 2, wherein in the step d, the base used for the alkali solution is NaOH or KOH.