| With the development of green chemistry, the research of benign environmental green solid base catalysts has attracted increasing attention present, due to their high activity and selectivity, as well as decreased corrosion and environmental problems.In present paper, KF-supported MgAl mixed oxides solid base was synthesized upon layered double hydroxides (LDHs) precursors and the KF was supported using a modified impregnation method for the first time. The C-C bond formation of Knoevenagel condensation and Michael addition were carried out over these catalysts to investigate the catalytic activity under solvent-free conditions.The structure and physico-chemical properties of the prepared catalysts were studied systematically. The novelty and major contents of the thesis were detailed as follows:The small-sized MgAl-CO3-LDHs prepared by the method involving separate nucleation and aging steps, the MgAl mixed oxides MAO (20-30nm) were obtained by proper calcination the MgAl-CO3-LDHs The KF-supported MgAl mixed oxides catalysts were firstly carried out by a novel impregnation-rotation method. The obtained precursors present well-resconstructed LDHs structure and greatly enlarged particle size. After proper calcination, a series of solid base catalysts KF/MAOic (i:KF loading amount) were obtained.The structural, thermal, surface compositions and base properties were examined by using XRD,FT-IR, SEM, TG/DTA-MS,XPS,19F and 27Al MAS NMR,Hammett indicator method,CO2 and NH3-TPD and in situ FT-IR techniques. The results manifest that the loading amount of KF significantly affected the acid-base property of the catalysts.The basicity is increased with KF loadings.No other crystal phase was observed until the KF loading to 11.8wt%, implying the monodisperse KF on the sample KF/MAO 11.8c.The basic strength is increased with KF loadings probably because of the interaction of KF with the support resulting in the basic sites [Al-OH…F-].The sample KF/MAO11.8c has the most amounts of the middle strength basic sites, being related with the greatly enhanced particle size(150-200nm) of catalyst compared with the support and the acidity of the samples originating from metal cations.The ratio of basic sites to acidic sites is 1.16.When the KF loadings amount more than 11.8wt%, the new phases of K3AlF6 and K2CO3 were observed on the catalysts resulting in the new basic sites[Al-CO32-…K+],and therefore further improved the base strength.In the Knoevenagel condensation of benzaldehyde with ethyl acetoacetate under solvent free conditions, the KF/MAO11.8c gave the highest activity with yield of 85% in 2h. However, with increase KF loadings, the catalytic activity is slightly decreased. This sample also show better catalytic activity in a series of condensation reactions with varied substrates, and this may be correlated to the highly dispersed F-and the the cooperative action of acid-base sites at KF/MAO11.8c.While in Michael addition of methyl acrylate and nitromethane under solvent free conditions, the KF/MAO30.1c show the highest activity with yield of 95% in 2h. Further increasing KF loadings, the catalytic activity is contrarily decreased. This sample also show better catalytic activity in a series of addition reactions with varied substrates, and this can be explained by its more basic sites and fewer acidic sites, especially the new surface basic sites[Al-CO32-…K+] probably played a key role.Corroborating the characterization results with reactivity, we tentatively prosoded the active site model of KF-supported MgAl mixed oxides solid base catalysts.
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