Fabrication Of Nanocatalysts With Multi-component And Their Catalytic Performance

Because of their unique physical and chemical properties,noble metal nanomaterials have been widely applied in many catalytic reactions,such as CO oxidation,nitroaromatics reduction,selective hydrogenation,electrocatalysis,and photocatalysis.Quite frankly,limited precious metal resource is a problem.So how to further optimize the catalytic properties of the noble metal nanomaterials or develop the alternative non-noble metal catalyst is worth considering.For the sustainable development,the thesis has effectively prepared a series of multi-component nanocatalysts by different strategies.Then,the relationships between structure and performance of nanocatalysts are studied in detail.I.Ammonium hydroxide was employed as the precipitant and complexant,and transition metal doped TiO2 supports(M-TO-x)were synthesized by the strategy of hydrothermal synthesis.The structure,morphology and composition of M-TO-x were characterized by XRD,TEM,EPR,Raman spectroscopy,nitrogen adsorption/desorption,and ICP-OES techniques.The results show that there presents a large number of structure defects on the surface of M-TO-x.Ammonium hydroxide plays a key role in the formation of such surface defect.Pd/M-TO-x catalysts were further prepared by solvent impregnation method.A detailed comparison was made on the basis of their unique doped structures and catalytic behaviors.XPS,H2-TPR,and EPR investigations revealed the evolution of surface oxygen vacancies and Cu oxidation state.The catalytic activity and structural characterization results of the Pd/Cu-TO-1 catalyst suggest that both Pd and Cu-doped TiO2 structural feature can have a synergistic effect on the catalytic behavior of generated multi-interface.II.Nanostructured titanium dioxide(TiO2-N)was prepared by an ammonia-assisted hydrothermal method.Then,a series of multicomponent catalysts were prepared,Pd and Bi co-supported on TiO2-N,by using a modified co-impregnation method.The CO oxidation activities of the multicomponent catalysts were detailedly compared by the different preparation methods,H2 activation,load amounts,calcination temperatures,and supports.Metal Pd and additives Bi are of high dispersion on theTiO2-N that was revealed by the XRD,Raman,TEM,and HAADF-STEM.In addition,H2-TPR analysis proved that the synergistic effect among metal Pd,additives Bi,and TiO2-N support.The results of XPS showed that multi-interface of the Pd-based catalysts may exist,owing to coexistence of a variety of metal and metal oxides.The catalytic activity and structural characterization results proved that an appropriate amount of Bi species has a clear promoting effect on the Pd-based catalyst.Particularly,the catalyst can be mass-produced conveniently,which may be beneficial for versatile reactions and practical applications.?.A series of CuCe bimetallic oxides with characteristic morphology had been constructed by using a 6-aminocaproic acid-assisted hydrothermal method,in which different hydrothermal temperature,hydrothermal time,and additives were respectively researched.Compared to CuCe-wl and 5%Cu/Ce02-c catalyst,the wire-network-like CuCe-10 catalyst exhibits the high catalytic activity and amazing stability in CO oxidation.The characterization results of TEM,XRD,H2-TPR,XPS and Raman spectra show that surface defects of the oxygen vacancy is the key to the catalytic activity.Moreover,it means that the introduction of 6-aminocaproic acid makes sense for tunable fabrication and enhanced catalytic performance.?.A series of alloy nanowires were conveniently synthesized in water using ethylenediaminetetraacetate(EDTA4-)as a structural controller and stabilizer,which are ultrafine with a width of approximately 6 nm.In the producing process of EDTA4-assisted nanowires,different cations(Co2+,Mn2+,Ni2+,Cu2+,Fe3+,and Ag+)and anions(PdCl42-,PtCl42-,and AuCl4-)were introduced and studied.The reduction of 4-nitrophenol by NaBH4 was used to evaluate the activity of the alloy nanowires catalysts.The EDTA4-assisted alloy nanowires exhibited excellent activity and stability,outperforming the bare nanowires and sodium citrate assisted nanowires,and indicating the EDTA4-has a great influence on the morphology and activity.