【作者】 齐奔；

【导师】 刘双喜；

【作者基本信息】 南开大学 ， 材料物理与化学， 2013， 博士

【摘要】 醇和烯烃的选择性氧化作为一类重要的研究课题在精细化工和基础工业中引起人们的广泛关注。环氧化物作为一类重要的有机化合物中间体,广泛的应用于手性药物、杀虫剂、环氧树脂、农药、香料和佐料等领域。环氧化物的传统合成工艺是卤醇法和过酸法,这些方法会对环境造成污染。苯甲醛是一种重要的有机中间体,广泛应用于合成染料、香料和药物等精细化学品等。目前,苯甲醛在工业上采用氯羊联合水解法或重铬酸和硫酸作氧化剂氧化苯甲醇制备而得。这种生产苯甲醛和环氧化物的工艺较复杂,而且对环境会造成污染。从原子经济学和绿色化学上考虑,采用分子氧或者双氧水催化氧化烯烃和醇是目前研究的热点。本文旨在寻求一种高效的催化剂,催化分子氧选择性氧化醇和双氧水环氧化烯烃。首先是采用氯化钯稀溶液为钯源,金属氧化物为载体,使用吸附法一步合成了Fe3O4、MnOx和CeOx负载的Pd催化剂,同时与吸附-还原法和共沉淀法制备的Pd/MOx作对比。对于无溶剂条件下分子氧催化氧化苯甲醇的反应,不同制备方法制备中,吸附法制得的催化剂显示出更好的催化性能,其中Pd/MnOx-ads表现出最高的催化活性和苯甲醛的选择性,而且其可以回收使用四次,催化剂的活性没有明显的下降。其次,采用了不同的方法制备了一系列的纳米钯负载在MCM-41的催化剂,并用这些催化剂在无溶剂的条件下催化氧气氧化苯基醇。催化剂通过XRD分析得出,当Pd负载在MCM-41后,依然保持着MCM-41的介孔结构,而且在Pd-M41-AE上并没有发现有大颗粒的Pd存在。研究表明催化剂制备的方法和Pd的负载量显著影响了催化剂的活性。相比Pd-AP-M41、Pd-M41-AC和Pd-M41-I, Pd-M41-AE显示出较高的催化活性。同样在100℃下反应1h,以0.4-Pd-M41-AE作为催化剂,苯甲醇的转化率可以达到33.8%,远远高于其他类型的催化剂,这主要归结于Pd颗粒较小,而且Pd纳米粒子大部分分布在MCM-41的孔口和外表面,这样有利于反应的进行。在160℃时,0.05-Pd-M41-AE显示出来极高的催化醇的活性,催化氧化苯甲醇的TOF达到69,162h-1,1-苯乙醇的TOF达到69,960h"1,肉桂醇的TOF达到117,130h-1。而且这个催化剂重复使用四次,苯甲醇的转化率和选择性没有明显的下降。第二部分内容是双氧水环氧化苯乙烯。首先,合成了一系列的锰氧化物和其他过渡金属氧化物,然后用这些氧化物在0℃下催化环氧化烯烃。很明显的,MnO显示出了最高的活性,当使用4当量的双氧水反应5h时,苯乙烯的转化率达到100%,远远高于其他的锰氧化物以及其它的过渡金属氧化物。MnO在催化环氧化苯基烯烃、苯基环己烯以及降冰片烯时显示出较高的催化活性,而对于α-蒎烯、环辛烯显示出较一般的催化活性,对于线性烯烃没有活性。此外,MnO表现出了较高的催化稳定性,重复使用四次催化剂的活性没有明显的下降。其次,分别采用了模板剂离子交换法、原位还原法、直接水热合成法和浸渍法合成了一系列的Mn-MCM-41,并且研究了它们的物理化学性质。在催化双氧水环氧化苯乙烯的反应中,催化剂Mn-M41-K-1和T-Mn-M41-1表现出了良好的催化活性,苯乙烯的转化率达到了99.5%。在催化剂回收使用过程中,Mn-M41-K-1可以重复使用四次,苯乙烯的转化率没有明显的降低；而T-Mn-M41-1在第一次回收时转化率降低一半,而且有锰的流失。采用浸渍法制备了不同载体的催化剂MnOx/y-Al2O3、MnOx/MCM-41、 MnOx/SiO2和MnOx/TiO2,以及一系列不同含量的MnOx/γ-Al2O3。在这些催化剂中,1.3-MnOx/γ-Al2O3表现出了最高的催化活性,催化苯乙烯的转化率达到了99.5%,远高于催化剂MnOx/MCM-41、MnOx/SiO2和MnOx/TiO2的活性。1.3-MnOx/γ-Al2O3能够很好的催化环氧化苯基烯烃,如苯乙烯、α-甲基苯乙烯,茚以及降冰片烯和环己烯,而对于环辛烯和α-蒎烯,表现出较差的催化活性。1.3-MnOx/γ-Al2O3催化剂能够重复利用四次,活性基本不变。更多还原

【Abstract】 The catalytic selective oxidation of alcohols and alkenes have been a subject of growing interest in the fundamental chemistry and modern industrial processes, since epoxides are key building blocks in organic synthesis. Epoxide compounds are commercially important intermediates used in the synthesis of products such as chiral Pharmaceuticals, pesticides, epoxy paints, agrochemicals, perfume materials and sweeteners. Traditionally, epoxides are produced by the epoxidation of alkenes with stoichiometric amount of peracid as oxidant. However, peracid is very expensive, hazardous, and the acid waste converted from the peracid is environmentally undesirable. Conventionally, stoichiometric oxidants (e.g., chromate or permanganate) have been used for oxidation of alcohols. However, lots of toxic wastes produced from the processes are environmentally undesirable. There has therefore been a drive to identify atom-efficient economic and green chemistry oxidation reaction that can be carried out with molecular oxygen and hydrogen peroxide. The present thesis therefore aims to develop an efficient catalyst, to produce the catalysts that can catalyze aerobic oxidation of alcohols or epoxidation of alkenes with hydrogen peroxide.The Pd nanoparticles supported on MnOx (Pd/MnOx-ads) has been synthesized via adsorption method. The Pd/MnOx-ads exhibited high activity and selectivity to benzaldehyde for aerobic oxidation of benzyl alcohol under free solvent, compared with Pd/Mn3O4, Pd/CeO2and Pd/Fe3O4catalysts. Moreover, the activity of Pd/MnOx-ads catalyst showed remarkably higher than those of catalysts prepared by adsorption-reduction and co-precipitation methods. The catalyst can be reused several times without obvious loss of its activity.The [PdCl4]2-ions were successfully supported on as;synthesized [CTA+]MCM-41materials through adsorption method. Subsequently, the composite materials were reduced by sodium borohydride, followed by being extracted of [CTA+] surfactants with acidified ethanol. The resulted solid (denoted as Pd-M41-AE) could be used as an efficient catalyst for the solvent-free aerobic oxidation of benzylic alcohol under atmospheric pressure.0.4%Pd-M41-AE exhibited high activity (turnover frequency of4,344h-1) for the oxidation of benzyl alcohol, remarkably superior than other kinds of Pd-M41at100℃. Moreover, the superior turnover frequencies (69,162h-1for benzyl alcohol,69,920h-1for1-phenylethanol and117,130h-1for cinnamyl alcohol, respectively) were achieved over0.05%Pd-M41-AE at160℃. Recycling studies proved the recyclability of Pd-M41-AE as a heterogeneous catalyst, which did not lose the catalytic activity after four recycles appreciably.A series of manganese oxides (MnO, Mn3O4, Mn2O3and MnO2) were prepared and firstly applied as heterogeneous catalysts for the liquid phase epoxidation of alkenes with30%H2O2in bicarbonate solution. Under our experimental conditions, MnO exhibited superior activity for the conversion of styrene to achieve ca.100%with92.4%selectivity of epoxide, compared to the other three manganese oxides as well as other metal oxides. Furthermore, recycling studies showed the good recyclability of MnO as a heterogeneous catalyst, which did not lose the catalytic activity after four reuses appreciably.Manganese containing mesoporous materials Mn-MCM-41were prepared by template-ion exchange (TIE), in-situ reduction (ISR), direct hydrothermal (DHT), and wetness impregnation (WI) methods. It has been found that the definite structure of the support was retained after introducing Mn into MCM-41. The catalytic activity and selectivity of the Mn-MCM-41in the epoxidation of styrene with30%H2O2as an oxidant agent are explored. The TIE catalysts showed the highest activity but Mn2+was leaching during the reaction. The ISR catalysts exhibited high activity and its very stability which could be recyclable for4times. However, the DHT and WI catalysts showed poor performance in the catalytic epoxidation of styrene.Manganese oxides supported on γ-Al2O3, amorphous SiO2, MCM-41and TiO2prepared by impregnation method were used as heterogeneous catalysts for epoxidation of alkenes with30%H2O2in the presence of NaHCO3aqueous solution. The effect of support and manganese loading on their activity was studied. The1.3%MnOx/γ-Al2O3exhibited superior epoxidazing activity of styrene, compared with other supported MnOx. Recycling studies showed the catalyst was a heterogeneous one and retained its activity after recycling for4times.更多还原