Preparation Of NiO, ZnO And WO₃Nanostructures And Their Catalytic Performance

In organic catalysis, how to improve conversion and selectivity of catalysis has been ahotspot. However, to this topic, the key is the development of research on catalysts. Catalystis a substance that does not change by itself, but refers to the change of other substancesreaction rate in the chemical reactions. It is well known the size, morphology and dispersionof catalyst can influence the catalytic activity. For this reason, the catalysts with smaller size,morphological diversity and highly dispersed have been favored by people’s preference.In this paper, NiO nanoplates, flower-like ZnO nanostructures, and WO₃nanorods weresynthesised by different method. These samples were characterized by transmission electron（TEM）, scanning electron microscopy （SEM） and X-ray diffraction XRD. The conclusion ofexperiment has several aspects, as follows:（1） A microwave-solvothermal method was conducted to synthesize NiO and Ag/NiOnanostructures of different proportion of silver, and investigated their catalytic epoxidation ofstyrene. With the increase of the amount of silver, the conversion and selectivity ofepoxidation of styrene are decreased. Next, NiO/bentonite of different mass of bentonite hasbeen testing their catalytic epoxidation of styrene. We found that the mass of carrier doesn’taffect the catalytic performance. When the quality of bentonite is0.8g, the catalytic result ofNiO/bentonite and NiO nanostructure are minor differences. But the separation effect ofcatalyst and reactant is greatly improved.（2） A microwave-thermal method was conducted to synthesize ZnO and Ag₂O/ZnO （themole rates of sliver and zinc are1:9and2:8） nanostructures of different proportion of silver.And then, the ZnO_caland Ag/ZnO_cal（the mole rates of sliver and zinc are1:9and2:8）nanostructure were synthesised by the400oC calcinations for2h. To these series of samples,we look at performance of epoxidation of styrene and photocatalytic degradation ofrhodamine B. Noticeably, the as-prepared Ag₂O/ZnO presented a better catalytic performancethan others. In epoxidation of styrene, the means of calcinations and loading of sliver both can improve catalytic performance. But in photocatalytic degradation of rhodamine B, the meansof calcinations can reduce catalytic performance of as-synthesised samples, and the order ofthe catalysts after calcinations for their performance is Ag₂O/ZnO（the mole rates of sliver andzinc is2:8）> ZnO> Ag₂O/ZnO（the mole ratios of sliver and zinc is1:9）。（3） WO₃nanorods have been synthesised with para aminobenzoic acid （PABA） as astructure-directing agent through a facile hydrothermal method. The （transmission electronmicroscopy） TEM results showed that most of the products had rods morphology with alateral size of50-80nm. The samples exhibited a high adipic acid catalytic performance, andthe better optimization conditions was as follows:8mmol cyclohexene,0.15mmol catalysts,10mmol oxalate and heated at90oC for12h.