- Thesis topic: The Modification Of Fly Ash With NaBr For NOx Removal Efficiency

- Doi: https://doi.org/10.6840/cycu202301561

- Abstract: 

        Because fly ash and nitrogen oxides are both air pollutants, they are likely to cause environmental pollution, and fly ash has the characteristics of adsorption. Therefore, the catalyst is made of modified fly ash to achieve long-term application and effectively control the emission of nitrogen oxides. In addition, the reuse of fly ash can also be achieved. In this study, the catalyst prepared by fly ash and sodium bromide was used to investigate the efficiency of removing nitrogen oxides by controlling the experimental parameters. The modified fly ash is divided into NaBr-FA-2.5%, NaBr-FA-5%, NaBr-FA-10% and NaBr-FA-20% according to the addition ratio, as a catalyst to achieve the effect of degrading NOx. According to the experimental results, the original fly ash has a removal rate of 4.4% at 25oC, while that of sodium bromide is 33.3%. Fly ash has an additive effect on the degradation of NOx. According to the temperature change experiment, the modified fly ash has the best removal efficiency at 150oC, the lowest is 72.7% of NaBr-FA-2.5%, and the best removal efficiency is 98.3% of NaBr-FA-20%. When the weight of the modified fly ash decreases, the removal rate decreases due to the indirect impact on the addition of fly ash and sodium bromide. The removal rates of 0.5g, 1g and 2g are 73.9%, 81.7% and 98.1% respectively, which can be seen at 500ppb The gas concentration of 2g is the best choice. According to the experimental results, the larger the particle size of fly ash, the lower the removal efficiency. It is only 76% at 0.5 mesh, 98.1% and 98% at 100 mesh and 200 mesh respectively, so it can be seen that 100 mesh of fly ash can achieve the best removal efficiency. When the nitrogen oxide concentration is 500ppb, 750ppb and 1000ppb, the removal rates are 98%, 98.2% and 97.7% respectively, which means that the modified fly ash has excellent removal ability at the nitrogen oxide concentration of 1000ppb. After a 72-hour stability test, NaBr-FA-20% can maintain a high removal rate of 98.2%, showing its high stability in removing nitrogen oxides. From the above results, it can be seen that the modified fly ash NaBr-FA-20% prepared in this research has the potential of commercial application.

Keywords: Fly Ash, NaBr, Nitrogen oxides, Catalyst, Modified fly ash