Hebei Messi Biology Co., Ltd. stated that the nano-magnesium oxide prepared by chemical method has excellent properties such as high purity, small particle size, large specific surface area, high hardness, high reactivity, strong adsorption and good low-temperature sinterability, and can be used as an environmental Adsorbents for pollution control.
In this study, a systematic study on the preparation of nano-magnesia powder and magnesium oxide-based adsorbent was carried out, and it was applied to the simultaneous desulfurization and denitrification test of flue gas. On this basis, the nano-magnesia The optimal method of adsorbent regeneration has obtained good treatment effect. At the same time, the adsorption mechanism of simultaneous desulfurization and denitrification of nano-magnesia adsorbent was studied and analyzed. The properties, uses and preparation methods of nano-magnesium oxide are reviewed, and the preparation methods of its powder and adsorbent are deeply studied.
The direct precipitation method combined with the microwave water bath heating method and the uniform precipitation method combined with the microwave water bath heating method were compared experimentally. The results found that MgSO4·7H2O and Na2CO3 were used as raw materials, and the surfactant polyethylene glycol 1000 was added, and the method of direct precipitation and microwave water bath heating method was used to prepare nano-magnesium oxide powder with good crystallization and large specific surface area. The effects of the reaction temperature and time of the precursor, the calcination temperature and time, and the amount of polyethylene glycol on the specific surface area of the powder were studied. Using thermogravimetric analysis (TGA), X-ray diffractometer (XRD), scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR), etc., to analyze the structure and morphology of nano-magnesia powder and its precursors The thermal decomposition temperature was analyzed.
The results showed that the nano-magnesia powder precursor was prepared by roasting at 500°C for 1.5h, the specific surface area reached the maximum of 183.35m2/g, and the average particle size was 7.2nm. :Tianjin powder=75:32:1, mass ratio) to prepare nano-magnesia-based adsorbent. In the self-designed and installed flue gas desulfurization and denitrification device, the simultaneous desulfurization and denitrification performance of the nano-magnesia-based adsorbent was investigated, the influence of various factors on the removal efficiency was explored, and the state of the adsorbent before and after simultaneous desulfurization and denitrification was characterized. . The results show that when the flue gas temperature is 120°C-180°C, the bed height is 5cm, the space velocity in the adsorption tower is less than 3400 h-1, and the flue gas is under aerobic conditions, the SO2 concentration is 2000mg/m3, and the NO concentration is 500mg/m3. Under the condition of m3, the desulfurization efficiency can be maintained at about 98.03% and the denitrification efficiency can be maintained at about 85.74% within 60 minutes of adsorption. The adsorbent has good stability.
In the regeneration experiment, thermal regeneration, water vapor regeneration and lye washing were carried out. By comparing the desulfurization and denitrification effects of the adsorbent after regeneration, it was shown that the lye regeneration method had the best regeneration effect, and through further experiments, it was found that: Soaking 5.37g nano-magnesia-based adsorbent with 0.25 mol/L, 100ml sodium hydroxide at 20℃ for 30min can achieve the best regeneration effect. The efficiency of simultaneous desulfurization and denitrification of the adsorbent regenerated by washing with alkaline solution is improved, the stability of the regenerated adsorbent for simultaneous desulfurization and denitrification is good, and the nano-magnesia-based adsorbent can be regenerated repeatedly. The self-designed and installed simultaneous desulfurization and denitrification adsorption-regeneration integrated pneumatic fluidized cycle treatment regeneration device was tested for 60 minutes of continuous test. The removal efficiency of S02 has been maintained at 100%, and the removal efficiency of NOx has remained above 74.3%.
Finally, the mechanism of simultaneous desulfurization and denitrification of nano-magnesia-based adsorbents was studied. BET, SEM, XRD, FT-IR, etc. were used to characterize and analyze nano-magnesia-based adsorbents before and after simultaneous desulfurization and denitrification and before and after regeneration. Mainly chemical adsorption. A series of complex chemical reactions occurred when 8O2 and NOx contacted with the adsorbent. After washing with alkaline solution, the surface of the adsorbent has increased basic groups, which is helpful for the removal of SO2 and NO, and it is speculated that the adsorbent can catalyze the oxidation of NO at this time, and the catalytic effect further improves the desulfurization and denitrification efficiency. Experiments show that the magnesium oxide-based adsorbent can be regenerated repeatedly, and the improved simultaneous desulfurization and denitrification adsorption-regeneration integrated system can be applied in actual production.