| It is well known that catalytic reaction has been the most important technique in many fields such as energy, biological and chemical production, and catalyst is crucial composition during catalytic reaction. In the catalyst research field people were searching for new and high efficiency catalyst at all times. In recent years, compared with the traditional metal catalysts, oxide catalysts have been aroused more and more attention due to their unique advantages such as simple preparation process, stable performance during the catalytic reaction and can avoid gathered in the reaction. In this dessertation, The CoMn2O4hierarchical microspheres assembled by nanosheets through thermal decomposition of precursor at different temperatures were first used as catalysts in the reduction of p-nitrophenol to p-aminophenol. The sample prepared at500℃shows the highest catalytic activity (kapp=14.95×10-3s-1), which is even higher than some results reported for noble metal particles (Au, Ag and Pd). It is suggested that the presence of metal oxide with ’d7’(Co element) and ’d5’(Mn element) electronic configuration and the special morphology of COMn2O4hierarchical microspheres are beneficial to the reduction of p-nitrophenol to p-aminophenol. Moreover, the MOF has been gotten more and more attention in recent years due to its’ large surface and regular morphology as well as the considerable active site. Here, MOF was also used as catalyst in the HMF catalytic hydrogenation, we tested the catalytic effect of four groups of MOF with different components in the experiment, according to the result, the four groups of catalysts all showed certain catalytic activity for the HMF catalytic hydrogenation. In addition, in the experiment, we also studied the different catalytic effects of the same Ce[Co(CN)6] with different morphology and the different catalytic effects of Ce[Co(CN)6] with same morphology but with different reaction conditions. The main research contents are as follows:The CoMn2O4precursor was prepared by hydrothermal method at first, then the precursor was calcined at different temperatures (400℃、500℃、600℃、700℃) to get CoMn2O4hierarchical microspheres with different crystallinity. SEM characterization showed that the four groups of CoMn2O4were all evenly distributed layered hierarchical microspheres structure. And the CoMn2O4hierarchical microspheres prepared at different temperatures showed no difference in the crystal phase, but it is worth nothing that the XPS showed that the Mn element exists as Mn2+and Mn3+in these catalysts, and the calcination temperature can affect the valence-state distribution of Mn. Though Co element also exits as two valence states (Co2+and Co3+) in these catalysts, the two peaks showed no significant change in these catalysts.CoMn2O4hierarchical microspheres prepared at different temperatures were used as catalyst in the reduction of p-nitrophenol to p-aminophenol, the difference of catalytic activity of the four groups of CoMn204hierarchical microspheres at room temperature has been discussed and the cycle stability during the reaction of the four groups of catalysts has been tested. According to the experimental results, the four groups of catalysts all have certain activity in the reduction of p-nitrophenol to p-aminophenol. No obvious catalyst deactivation phenomenon appeared during the six cycle experiments, this means that the catalyst has good stability. The sample prepared at500℃showed the highest catalytic activity, even higher than that preciously reported for metal catalysts in the literature, this means CoMn2O4hierarchical microspheres catalysts are a kind of novel catalytic materials with broad development prospect and can be applied in industrial production of p-nitrophenol. Finally, combined with the experimental results and related literature reports, a possible catalytic mechanism of the reduction of p-nitrophenol was proposed. According to the reaction mechanism, the redox couples Co3+/Co2+and Mn3+/Mn2+of CoMn2O4hierarchical microspheres were very important during the reaction as the synergy effect between the two redox couples was conducive to the transfer of electron.MOF was directly used as catalyst for the hydrogenation of HMF in this dissertation. Four types of MOF with different components were used as catalysts in the experiment, and all the four MOFs showed catalytic activity in the hydrogenation of HMF. It is found that Ce[Co(CN)6] showed the highest catalytic activity. Then, the catalytic activity of Ce[Co(CN)6] with different morphology were also studied, and the result suggested the Ce[Co(CN)6] with petal-shape has the highest catalytic activity compared to hexagon-shape and dodecahedron-shape. It should be noted that the results are preliminary, further research needs to be carried out, such as analysizing products and investigating the catalytic mechanism. |
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