| The pollutants discharged by firing coal bring a series of environmental issues,and the excessive emission of nitrogen oxides(NOx)is one of the main reasons for atmospheric pollution.In order to effectivly controlling the emission of NOx in the process of coal firing,a lot of reduction technologies and engineering practices have been developed at home and abroad.At present,the main technologies used in coal-fired power plants are selective catalytic reduction(SCR)and selective non-catalytic reduction(SNCR),these methods make nitric oxide(NO)decompose to water and nitrogen with or without catalysts respectively.However,NOx is one of the chemical raw materials,among which NO molecule also has the important meaning in biomedicine field.For accommodating the significant demand of our country to build a conservation-minded society,series adsorption materials were prepared based on molecular imprinting technique and the experiments of NOx adsorption/desorption in flue gas were conducted in order to get a kind of adsorbent which could make NOx adsorb and desorb easily in order to be in favor for the reuse of NOx.A series of molecularly imprinted adsorbents were prepared and optimized using different template molecules and functional monomers with the method of bulk polymerization based on the theory of molecular imprinting technique.N2 adsorption isotherm experiment and thermo-gravimetric analysis experiment were used to study the specific surface area,pore size and thermo-stability of adsorbents which were affected by different template molecules and functional monomers.Infrared spectrum experiment was used to analyze chemical structure of each adsorbent,besides,the chemical structure of the adsorbents before and after NOx adsorption was also investigated.NOx adsorption capacity of each adsorbent was tested and compared in fixed-bed adsorption equipment.NOx desorption experiments were also conducted in order to investigate the regenerability of the adsorbents.In order to study NOx adsorption effect of molecularly imprinted adsorbents in simulated flue gas,the temperature,flue gas rate and NOx concentration at the inlet of the column were changed to discuss the effect of adsorption column conditions to NOx adsorption,and the basic experimental conditions were established.The experiments of study the effect of coexistent gases in simulated flue gas to NOx adsorption by molecularly imprinted adsorbents were also carried on,and the effect laws of H2O,O2,SO2 and CO2 to NOx adsorption in flue gas were analyzed.Besides,through the calculation of the mass transfer coefficients of NOx in adsorption column,the mass transfer process was researched the controlling step during the mass transfer process was decided.In order to improve the utilization of the functional monomer,three kinds of modified silica-gel adsorbents which were silica gel grafted with vinsyltriethoxysilane(S1),acrylic acid polymer wrapping silica gel(S2)and acryl amide polymer wrapping silica gel(S3)were prepared on base of activated silica gel(S0)to realize the uniform distribution of functional monomers on the surface of silica gel and were used to adsorb NO.N2 adsorption isotherm experiment,thermo-gravimetric analysis experiment,infrared spectrum experiment and scanning electron microscopy were conducted to analyze the pore size distribution,thermal-stability,chemical structure and apparent structure of the modified silica gels.NO adsorption/desorption experiments of Si,S2 and S3 were conducted on the fixed-bed adsorption column to study NO adsorption ability and regeneration performance of the adsorbents.The mechanism of NO adsorption,the distinction of NO adsorption ability and regeneration performance of different materials were revealed by analyzing the physical and chemical property of the adsorbents,that also providing a reference to the preparation method of modified silica gel. |
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