Doping Of Ordered Mesoporous Carbon And Synthesis Of Ordered Mesoporous X Zeolite Molecular Sieve

This thesis focuses on the syntheses of ordered mesoporous X zeolite molecular sieve,N-doped and highly dispersed metal oxide-doped ordered mesoporous carbon materials.In the first part,tetraethyl orthosilicate(TEOS)was used as a silicon source,instead of sodium silicate,to synthesize X-type zeolite from a clear silicon-aluminum source.And then,ordered mesoporous carbon CMK-3 was used as a template to synthetize ordered mesoporous X zeolite molecular seive;in the second part,EDTA was used as carbon-nitrogen precursor to prepare N-doped ordered mesoporous carbon material via hard template route.X-ray powder diffractometer,low temperature nitrogen adsorption,scanning electron microscope,transmission electron microscopy,elemental analysis and X-ray energy spectrometer were used to characterize the prepared samples,and the electrochemical properties were also detected.The effects of different additives on the ordered mesporous structure and electrochemical properties of the samples were discussed emphatically;in the last part,a highly dispersed metal oxide-doped ordered mesoporous carbon material was prepared by the aid of complex effect of EDTA.The main progresses of this thesis are:1.It is difficult to avoid the occurrence of mixed crystals via the one-step synthesis of NaX,using TEOS as the silicon source and sodium aluminate as the aluminum source.While low silica-alumina ratio KNaX zeolite with higher purity can be synthesized via a modified two-step method,by introducing a 40℃ stirring to avoid the formation of mixed crystals.In the synthesis of ordered mesoporous X-type zeolite,we have attempted to remove impurities adsorbed in the pores of CMK-3,oxidize CMK-3 or dope nitrogen to increase its hydrophilic properties,optimize the solid/liquid ratio,and take the multiple impregnation-hydrothermal crystallization pathway,however,none of them worked well.The main reason is that mesoporous pores of template cannot be completely occupied by raw material solution,resulting in the collapse of ordered mesoporous structure after removing the template.2.N-doped ordered mesoporous carbon material cannot be formed by directly using EDTA as carbon-nitrogen precursor and SBA-15 as template.The introduction of ethylenediamine or ammonia auxiliaries can improve the dispersion of EDTA in SBA-15 channel,and nitrogen doped ordered carbon material(NOMC)was then successfully synthesized.The difference of templates had a great influence on the ordered structure of resulting materials.NOMC synthesized using SBA-15 synthesized at 120℃ for 10 h as template exhibits ordered mesoporous structure significantly superior to those synthesized using other SBA-15,MCM-41 and KIT-6 templates.Raising carbonization temperature can increase the specific surface of the resulting samples,but reduce the content of nitrogen;physical or chemical activation treatment such as water vapor and nitric acid can further improve the specific surface area of samples.These NOMC materials exhibited good electrochemical performance when used as the electrode materials for supercapacitor.Compared to NOMC materials synthesized using ammonia as an auxiliary agent,NOMC materials synthesized using ethylenediamine as an auxiliary agent has higher order of mesoporous structure,more pyridinium nitrogen,and thus exhibited superior electrochemical performance.Its specific capacitance is 50%higher than the pure mesoporous carbon CMK-3.3.Cu/N co-doped ordered mesoporous carbon materials were prepared by using SBA-15 as template and complexing copper acetate with EDTA as precursor.Copper existed mainly in the form of CuO and highly dispersed on the surface of the carbon material.