本文選題：溫控自分離　切入點：納米金催化劑　出處：《湖南師范大學(xué)》2015年碩士論文

【摘要】：納米金催化劑在醇類選擇性氧化反應(yīng)中有很好的催化性能,是目前納米金催化領(lǐng)域的研究熱點。近年來,溶膠型納米金催化劑作為擬均相納米金催化劑受到了廣泛關(guān)注。該類催化劑中的納米金活性中心能與反應(yīng)底物充分接觸,因而在液相選擇性氧化反應(yīng)中展示出很高的催化效率。由于溶膠型納米金催化劑采用有機(jī)化合物作為金納米粒子穩(wěn)定劑,常存在催化劑難以分離,回收使用困難的問題。任務(wù)導(dǎo)向型離子復(fù)合物的陰陽離子結(jié)構(gòu)可以根據(jù)特定需要進(jìn)行功能化修飾,同時,離子復(fù)合物表面張力很低,能很好的穩(wěn)定納米粒子,因而以其作為溶膠型納米金催化劑的穩(wěn)定劑,有可能解決催化劑的分離問題。本論文在前期研究結(jié)果的基礎(chǔ)上,以聚乙二醇(PEG)修飾任務(wù)導(dǎo)向型離子復(fù)合物,利用PEG在甲苯中的特殊溫控相變性能,得到具有溫控自分離特性的溶膠型擬均相納米金催化劑,并考察了其在醇類選擇性氧化中的催化性能,具體工作如下:(1)選取PEG6000合成了氯離子為陰離子的乙烯基功能化離子復(fù)合物[PEG6000VIM][Cl],通過陰離子交換反應(yīng),將乙酸根陰離子引入其中,合成了乙酸根為陰離子的乙烯基功能化離子復(fù)合物[PEG6000VIM][Ac]。分別以上述兩種離子復(fù)合物作為穩(wěn)定劑制備了相對應(yīng)的納米金催化劑[PEG6000VIM][Cl]-GNPs和[PEG6000VIM][Ac]-GNPs。以分子氧為氧化劑,考察了兩種催化劑在無堿條件下苯甲醇選擇性氧化反應(yīng)中的催化性能,相比于含氯離子的催化劑[PEG6000VIM][Cl]-GNPs及文獻(xiàn)中納米金催化的同類反應(yīng),含乙酸根的離子復(fù)合物穩(wěn)定的納米金催化劑[PEG6000VIM][Ac]-GNPs表現(xiàn)出大為提高的TOF值。優(yōu)選了金含量為0.065wt%的[PEG6000VIM][Ac]-GNPs-0.065作為最佳催化劑,考察了溶劑甲苯的用量、反應(yīng)溫度、催化劑用量及反應(yīng)時間對苯甲醇選擇性氧化反應(yīng)的影響,在最佳反應(yīng)條件下,催化劑的TOF值達(dá)到了0.63 mol·g-1·h-1。(2)為提高苯甲醇的轉(zhuǎn)化率,引入了第二種金屬到催化劑[PEG6000VIM][Ac]-GNPs中,制備了常見的金基雙金屬催化劑Au-Cu/[PEG6000VIM][Ac]、Au-Ag/[PEG6000VIM][Ac]、Au-Mn/[PEG6000VIM][Ac]、Au-Pd/[PEG6000VIM][Ac],從中優(yōu)選了催化劑Au-Pd/[PEG6000VIM][Ac]。對催化劑中Au-Pd含量及組成結(jié)構(gòu)進(jìn)行了優(yōu)化,得到了最佳催化劑Au1Pd7/[PEG6000VIM][Ac]-0.6:Au-Pd摩爾比為1:7,Au與Pd總金屬含量為0.6 wt%。在最佳反應(yīng)條件下,該催化劑的苯甲醇轉(zhuǎn)化率和苯甲醛選擇性分別達(dá)到98.3%和99.0%。
[Abstract]:Nanocrystalline gold catalysts have good catalytic performance in the selective oxidation of alcohols.In recent years, sol-type nanocrystalline gold catalysts as pseudo-homogeneous nanocrystalline gold catalysts have attracted wide attention.The nanometer gold active center in this kind of catalyst can fully contact with the substrate, so it shows high catalytic efficiency in the liquid phase selective oxidation reaction.Due to the use of organic compounds as stabilizers of gold nanoparticles in sol-type nanocrystalline gold catalysts, it is often difficult to separate the catalysts and recycle them.The cationic and anion structures of task-oriented ionic complexes can be functionalized according to specific needs. At the same time, the surface tension of ion complexes is very low and the nanoparticles can be well stabilized.Therefore, it is possible to solve the problem of catalyst separation by using it as a stabilizer of sol-type nano-gold catalyst.Based on the previous research results, the task-oriented ionic complexes were modified with polyethylene glycol (PEG), and the sol-like pseudo-homogeneous nano-gold catalysts with temperature control self-separation properties were obtained by using the special temperature-controlled phase transition of PEG in toluene.Its catalytic performance in selective oxidation of alcohols was also investigated. The main work was as follows: (1) PEG6000 was selected to synthesize vinyl functionalized ion complex [PEG6000VIM] [Cl] with chloride ion as anion, and the acetate anion was introduced into it by anion exchange reaction.Vinyl functionalized ionic complex [PEG6000VIM] [ac] with acetate as anion was synthesized.The corresponding nanocrystalline gold catalysts [PEG6000VIM] [Cl] -GNPs and [PEG6000VIM] [ac] -GNPs were prepared by using the above two ionic complexes as stabilizers, respectively.The catalytic properties of two catalysts for selective oxidation of benzyl alcohol under alkali-free conditions were investigated by using molecular oxygen as oxidant. Compared with the catalyst [PEG6000VIM] [Cl] -GNPs containing chlorine ion and the similar reactions catalyzed by gold nanoparticles in literature, the catalytic performance of the two catalysts was compared with that of the catalyst [PEG6000VIM] [Cl] -GNPs containing chloride ions.The [PEG6000VIM] [ac] -GNPs prepared by ionic complex containing acetic acid showed a significant increase in TOF value, and the gold nanocrystalline catalyst [PEG6000VIM] [ac] -GNPs showed a significant increase in TOF value.[PEG6000VIM] [ac] -GNPs-0.065 with gold content of 0.065 wt% was selected as the best catalyst. The effects of the amount of toluene, reaction temperature, catalyst amount and reaction time on the selective oxidation of benzyl alcohol were investigated.鍌寲鍓傜殑TOF鍊艱揪鍒頒簡0.63 mol路g-1路h-1.(2)涓烘彁楂樿嫰鐢查唶鐨勮漿鍖栫巼,寮曞叆浜嗙浜岀閲戝睘鍒板偓鍖栧墏[PEG6000VIM][Ac]-GNPs涓，

本文編號：1709758