Preparation And Characterization Of SBA-15Supported Pd Catalyst For CO Oxidation

This discussion focus on the synthesis of the bimetallic nanomaterial and Pdnanomaterial within the uniform channels of the mesoporous SBA-15via the glowdischarge plasma. Then the CO oxidation is applied for the test of the catalysisperformance of these material. In order to characterize the physical and chemicalperformance of the synthesized materials, a serials of techniques are employed,including transmission electron microscope （TEM）, X-ray diffraction （XRD）, X-rayphotoelectron spectroscopy （XPS）, N₂physical adsorption-desorption, temperatureprogrammed oxidation （TPO）, Fourier transform infrared spectroscopy （FT-IR）, UVvisible spectroscopy （UV-vis）, CO chemical adsorption, energy dispersive x-rayspectroscopy and STEM.The bimetallic noble nanomaterial have been synthesized within the orderedchannels of the silica SBA-15through the wet impregnation method via the glowdischarge plasma reduction. The TEM results show that the synthesized materialhave the particular morphology: Au-Pd bimetallic nanoparticle, Au-Ag nanowire,Ag-Pd nanowire and Pt-Pd nanorod. And the results of the EDX and STEM indicatethat in the material Au-Pd and Ag-Pd, the metal elements have a particulardistribution. The significance of this new synthesis method through the glowdischarge plasma is that it is simple, facile, green and economic.The highly dispersed Pd nanoparticles were synthesized via the glow dischargeplasma, and then was further calcined in O2atmosphere and subsequently in H2atmosphere. The glow discharge plasma can reduce the Pd²⁺ into metallic Pdcompletely. The further treatment leads to some changes of the Pd surface. The COdrift indicates that there are some similarities and differences in the size, valencestate, the bridge adsorption strength and the CO adsorption enthalpy between twosamples. And these aspects were verified by the results of CO oxidation, TEM, XRD,CO chemisorption, the calculation of TOF and XPS. Also the stability of the materialwas investigated. The results show that not only the material has the structurestability, but also the reaction stability.The influence of state of the palladium on the CO oxidation was alsoinvestigated. The results obtained indicated that the Pd state has a dramaticallyinfluence on the performance of CO oxidation. The difference on the initial conversion, ignition temperature and completely conversion temperature is obvious.XPS results show that after CO oxidation, some PdO of the surface was reduced toPd⁰.