本文選題：LDHs + 剝層　； 參考：《太原理工大學》2017年碩士論文

【摘要】：Layered Double Hydroxides(LDHs)是由帶正電荷的二維層板與層間平衡電荷陰離子及水分子組成的一類層狀無機材料。層板表面可調的酸堿度,層板陽離子和層間陰離子化學組成可調控等特性使LDHs作為載體在制備負載型催化劑用于多相催化方面有廣闊的應用前景。但是由于LDHs層板堆積嚴重,層間距小,比表面利用率低,制約了活性組分在其上的分散度。因此,為了解決上述問題,本文選擇Pd為活性組分,擬主要從LDHs載體的改性及Pd的負載方式這兩個方面進行研究,制備出高分散度的LDHs負載Pd催化劑。主要研究內容包括:一是通過剝層和嫁接APTS改善LDHs的結構,制備出高度分散,大比表面的納米層片,將其作為載體以提高Pd的分散度;二是改變負載Pd所采用的溶劑,在乙醇中制備出小粒徑,高分散的負載Pd催化劑。具體研究結果如下:1)APTS改性LDH納米層片負載Pd催化劑的制備表征及催化性能研究采用AMOST法制備了疏松多孔的LDH納米層片并以有機硅烷APTS對其表面改性制得一種新的載體,再負載貴金屬Pd制備出催化劑。通過XRD、FT-IR、N2吸附-脫附、TEM、EDS等表征手段對所得樣品進行了詳細的表征。結果表明,APTS嫁接到LDH納米層片上,使負載的Pd納米粒子的粒徑減小,分散度提高,分布范圍變窄。在苯甲醇的無溶劑氧化反應中,APTS改性的催化劑表現出更高的催化活性與選擇性,重復使用性和穩(wěn)定性良好。本研究表明APTS改性是一種有效增強表面堿性,改善LDH納米層片上Pd納米粒子的分布,減小粒徑尺寸,增強金屬-載體間相互作用的良好途徑。2)乙醇溶液制備高分散度的LDHs負載Pd催化劑分別以水和乙醇為溶劑,以傳統共沉淀法方法合成的LDHs(LDH-co)為載體,采用Sol-immobilization法和浸漬法制備了負載Pd催化劑。通過TEM表征發(fā)現,無論采用何種方法,乙醇溶液中所得樣品,Pd納米粒子都具有分散度高,平均粒徑小,分布范圍窄等特點;而在水溶液中制備的催化劑,Pd粒子的團聚現象嚴重,分散度差、粒徑較大。3)選擇乙醇為溶劑,分別以傳統方法合成的LDHs,LDH納米層片及APTS改性的LDH納米層片為載體,采用Sol-immobilization法制備了負載Pd催化劑,通過苯甲醇氧化反應測試發(fā)現,以傳統方法合成的LDHs為載體的催化劑(Sol-Pd/LDH-co)可以達到剝層改性處理的催化效果。本研究極大地簡化了催化劑的合成步驟,減少了有機溶劑的使用,提高了制備效率,符合綠色化學和可持續(xù)發(fā)展的理念。
[Abstract]:Layered Double Hydroxidesus (LDHs) is a kind of layered inorganic material composed of positively charged two-dimensional laminates and interlaminar equilibrium charge anions and water molecules. The adjustable acidity on the surface of the laminates, the controllable chemical composition of the cation and the interlayer anions on the laminates make LDHs as the carrier for the preparation of supported catalysts for heterogeneous catalysis. However, the dispersion of active components on LDHs laminates is restricted because of their serious stacking, small interlayer spacing and low specific surface utilization. Therefore, in order to solve the above problems, PD was chosen as the active component in this paper, and the modification of LDHs support and the loading mode of PD were studied to prepare the PD catalyst with high dispersion degree of LDHs. The main research contents are as follows: firstly, the structure of LDHs is improved by stripping and grafting APTS, and the highly dispersed and large surface nano-layer is prepared, which is used as the carrier to improve the dispersion of PD; the other is to change the solvent used in the loading of PD. The supported PD catalyst with small particle size and high dispersion was prepared in ethanol. The results are as follows: (1) the preparation of LDH nano-layer supported PD catalyst? Characterization and Catalytic Properties of porous LDH Nanolayers prepared by AMOST method a novel support was prepared by surface modification of organosilane APTS and a catalyst was prepared by loading noble metal PD. The samples were characterized in detail by means of XRD- FT-IRN _ 2 adsorption-desorption EDS and so on. The results show that the grafted LDH nanoparticles can reduce the particle size, increase the dispersion and narrow the distribution range. In the solvent-free oxidation of benzyl alcohol, the catalyst modified by APTS showed higher catalytic activity and selectivity, good reusability and stability. The results show that the modification of APTS is an effective way to enhance the surface alkalinity, improve the distribution of PD nanoparticles and reduce the particle size of LDH nanolayers. A good way to enhance metal-carrier interaction. 2) ethanol solution was used to prepare LDHs supported PD catalyst with high dispersion. LDH-cocatalyst was synthesized by traditional coprecipitation method using water and ethanol as solvent, respectively. Supported PD catalyst was prepared by Sol-immobilization method and impregnation method. By TEM characterization, it was found that, no matter what method was used, the Pd nanoparticles obtained in ethanol solution had the characteristics of high dispersion, small average particle size and narrow distribution range, while the aggregation of Pd nanoparticles prepared in aqueous solution was serious. The supported PD catalyst was prepared by Sol-immobilization method, which was prepared by Sol-immobilization method. The results showed that the supported PD catalyst was obtained by the oxidation reaction of benzyl alcohol, and the supported PD catalyst was prepared by using the traditional method and the APTS modified LDH nano-layer as the support, respectively, using ethanol as the solvent, the particle size of which was larger than .3. the results showed that the supported PD catalyst was prepared by the method of Sol-immobilization. Sol-PD / LDH-coo catalyst supported on LDHs synthesized by traditional method can achieve the catalytic effect of delamination modification. This study greatly simplifies the synthesis steps of the catalyst, reduces the use of organic solvents, improves the preparation efficiency and conforms to the concept of green chemistry and sustainable development.
【學位授予單位】：太原理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O643.36

【參考文獻】

相關期刊論文 前10條

1 王瑞瑞;趙有t，

本文編號：1782989