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    铜和铈改性钒钨钛催化剂对烟气中一氧化氮和二氯甲烷的协同脱除技术

    Synergistic removal of NO and dichloromethane from flue gas over Cu/Ce modified V-W/Ti catalysts

    • 摘要: 氮氧化物与二氯甲烷会引发O3和PM2.5等一系列大气污染物的生成,引起全世界的广泛关注。通过多步浸渍法制备了一系列Cu和Ce改性V-W/Ti型催化剂,并将其应用于125~325 ℃的温度区间内协同脱除NO和二氯甲烷。测定了这一系列催化剂在不同工况下协同脱除NO和二氯甲烷的性能,通过扫描电子显微镜(SEM),X射线衍射(XRD),X射线光电子能谱技术(XPS)和氨气程序升温脱附(NH3−TPD)等表征技术对催化剂的理化特性进行了分析,并使用气相色谱−质谱联用仪(GC−MS)对尾气中的有机气体成分进行分析。结果表明,Cu和Ce的负载显著提高了催化剂的性能,拓宽了催化剂的活性温度范围。Cu的最佳负载比例为5%,当反应温度为225 ℃时,催化剂的NO脱除率最高可达90.4%。250 ℃时,二氯甲烷脱除率最高达到96.0%。改性V-W/Ti型催化剂具有更多的孔结构、更大的比表面积和更好的氧化还原能力,且抗硫、氯能力得到了极大的改善。在HCl氛围下,NO和二氯甲烷脱除效率仅分别降低了7.8%和6.4%。当SO2存在的情况下,改性催化剂对二氯甲烷的脱除效率仍能达到80.0%以上。NO初始浓度的提高对二氯甲烷的脱除性能也具有显著的促进作用,当NO初始浓度为600×10–6时,二氯甲烷脱除率最高可达97.5%,体现了V-W/Ti型催化剂在脱除这2种污染物时的协同效应。

       

      Abstract: NO and dichloromethane trigger the generation of a series of atmospheric pollutants such as O3 and PM2.5, which has attracted extensive attention worldwide. A series of Cu and Ce modified V-W/Ti catalysts were prepared by a multi-step impregnation method and applied to the synergistic removal of NO and dichloromethane in the temperature range of 125–325 ℃. The synergistic removal of NO and dichloromethane by these catalysts under different operating conditions was measured. The physical and chemical properties of the catalysts were analyzed by characterization techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ammonia programmed temperature-raising desorption (NH3−TPD). The organic gases in the tail gas were analyzed by gas chromatography-mass spectrometry (GC−MS). The results showed that the loading of Cu and Ce significantly improved the performance of the catalysts and broadened the activity temperature range of the catalysts. The optimum loading ratio of Cu was 5%, and the catalysts achieved up to 90.4% NO removal when the reaction temperature was 225 ℃. The maximum dichloromethane removal was 96.0% at 250 ℃. The results also showed that the catalysts were suitable to produce dichloromethane at a high temperature. The modified V-W/Ti catalysts have more pore structure, larger specific surface area, and better redox capacity, and the resistance to sulfur and chlorine was greatly improved. The NO and dichloromethane removal efficiencies were only reduced by 7.8% and 6.4%, respectively, under the HCl atmosphere. In the presence of SO2, the removal efficiency of dichloromethane could still reach more than 80.0%, and the increase in the initial concentration of NO also had a significant effect on the removal performance of dichloromethane, with a maximum removal rate of 97.5% at an initial concentration of NO of 600×10–6, which demonstrated the synergistic effect of the V-W/Ti catalysts in the removal of these two pollutants.

       

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