Preparation Of Water-resistance Fe-Co-O Catalyst And Its Catalytic Performance For Low Temperature CO Oxidation

Transition metal oxide catalysts (such as Co3O4 catalysts, etc.) are very sensitive to water vapor, and easily deactivated under moisture-rich condition. In the practical process of low-temperature CO catalytic oxidation, the activity of the catalyst will be inevitably influenced by many factors such as water vapor, CO2 and so on. Hence, the improvement of the catalyst activity and stability for CO oxidation under moisture-rich condition is very important for both academic value and practical utilization.In this thesis, the influence of the compositions, preparation conditions on the physicochemical and catalytic properties of Fe-Co-O catalyst were studied, which were characterized by low-temperature N2 absorption, XRD, XPS, FT-IR, H2-TPR, CO/O2-TPD,NMR, TG and TEM, etc. The CO adsorption and surface reaction on the catalyst were investigated by in situ DRIFTS, and the effect of the surface polymer layer content on the water resistance of the catalyst was studied. The main results were obtained as follows.The effects of the composition, preparation methods and conditions on the catalytic performance of Fe-Co-O catalyst were investigated. The results showed that, the catalyst prepared by solid phase method exhibited higher catalytic activity for CO oxidation than that prepared by co-precipitation under both normal (3-10 ppm H2O) and moisture-rich (0.6vol.%H2O) conditions. And its activity for CO oxidation was significantly increased by doping Fe,and adding oxalic acid (OA) and ethylene glycol (EG) in the preparation process. When Fe/Co=3/16, the Fe3Co16O, exhibited the best catalytic performance for low temperature CO oxidation.The effect of the calcination temperature on the catalytic performance of Fe-Co-O catalyst was studied. It showed that the nanofilm-coated Fe3Co16Ox nanoparticles calcined at 250?possessed higher surface area, Co3+/Co2+ ratio and oxygen vacancy, thus it exhibited the excellent catalytic perf-ormance for CO oxidation, such as, T100 of -101? under normal moisture (3-10 ppm) and T100 of 70? under moisture-rich (?0.6vol.%). Remarkably,its catalytic activity was hardly lost, after it was used more than one month under high moisture level (3.1vol.%) and relatively low temperature (90?), which shows its very high stability.The influence of moisture and CO concentrations on the CO oxidation over Fe-Co-O catalyst was investigated. We have found that this catalyst under moisture-deficit condition is much more sensitive to CO concentration than that under moisture-rich condition, indicating that there are different reaction routes for two cases above. The presence of water promoted the formation of more carbonate species by adsorbed CO reacting with surface OH-* (CO* ?OH* ? COOH* +*, * is the adsorption site). The polymer nano-film coated on the Fe3Co16Ox catalyst can isolate water molecules from the coated metal oxides to inhibit water molecules adsorbing on the active sites of catalyst.The influence of polymer layer on the catalytic performance of the Fe-Co-O catalyst was investigated. The results showed that the coating polymer on the catalyst surface is possibly consisted of -(CH2CH2-O-COCOO-)n. Calcination temperature would obviously affect the thickness of the polymer surface layer and content. And the existence of coating polymer can inhibit the growth of catalyst nanoparticles, further improve the water-resistance and stability of the Fe-Co-O catalysts.