Investigation Of Modified Carbon-based Catalyst On Low-temperature Selective Reduction Denitration Performance

NOx is one of the important atmospheric pollutants. In the current industry, selective catalytic reduction (SCR) is the one of effective method to remove NOx in the flue gas from stationary sources. In recent years, because of the very good economic and great industry background, the low temperature SCR has become a research hotspot. However, based on the review of the home and abroad, the low-temperature SCR technology industrial obstacle is the low activity at low temperature, poor SO2 resistance and H2O resistance. Therefore, in order to solve these problems, the paper use activated carbon as the carrier, transition metal element as the active component and study on the low-temperature SCR(about 100℃).Firstly, the low-temperature SCR of AC (space velocity 15000h-1) was studied. The result showed that AC first denitration rate was 50%, the late steady at 18%.Under the condition of 100℃, AC showed adsorption and catalytic combined action, but the activity is not high.Secondly, in order to improve activity, the low-temperature DeNOx catalyst based on activated carbon was prepared by immersion precipitation method. The surface structure of activated carbon is modified by oxidation and metal ion exchange, which greatly improves the dispersion and loading of active metal oxide. The added promoter urea shows beneficial to uniform distribution and precipitation of metal oxides in the process of immersion precipitation, additionally it can improve carbon adsorption of NH3 and active metal oxide surface in the process of the calcination, and increase the NO removal efficiency. Low-temperature SCR catalyst have been made based on three kinds of different specifications of carbon materials (Ci, C2 and C3).In the flue gas denitration test with different operating temperature range of 90-110 ℃ and space velocities (7500-25000 h-1), the result shows that C1 and C2 has high removal efficiency, and space velocities has great influence on the removal efficiency of activated carbon. This procedure yielded catalysts that, in conditions of high space velocities(15000h-1), showed a high catalytic activity at 100℃, with stable NOx conversions close to 86%; The sequence of ammonia into the device has great influence on denitration efficiency. Priority injection of ammonia contributes to better occupation on adsorption sites of catalyst, and increases denitration reaction rate.Then, the paper studies SO2 resistance and water resistance of the low temperature SCR catalysts, the result shows that SCR catalysts for resistance of low concentration SO2 is good, but the influence of water is great, The higher the moisture content, the worse the activity. The influence of H2O is reversible, When the moisture content is 0.05 and the temperature is higher than 140 ℃, H2O affect very small.