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研究了Mn-W/TiO2用于NH3选择性催化还原NOx体系的催化反应性能,探索了不同温度条件下该催化剂对抗不同SO2浓度的抗毒性能。结果显示WO3能够增加活性酸中心的数量和酸性,是MnOx/TiO2非常有效的助催化剂。在气体体积空速(gaseous hourly space velocity,GHSV)为18900h-1时100～350℃范围内,Mn-W/TiO2催化剂还原NOx的转化率高达80.3%～99.6%,N2选择性达100%～98.7%。当反应气中有0.01%SO2和6%H2O时,120℃NOx转化率可维持在98.5%,当SO2浓度超过0.01%时,则需将反应温度升高到250℃以上才可消除其干扰,而当SO2浓度高达0.07%时,300℃下转化率可长期维持在99%,达到了商用V-W/TiO2催化剂的水平。对于NH3选择性还原NOx体系Mn-W/TiO2显示了极好的催化性能,是目前抗SO2毒性最强的催化剂之一。试验发现,低温条件下,SO2对Mn-W/TiO2催化剂的影响是可逆的,随着反应温度的提高,活性将自然恢复。
The catalytic activity of Mn-W / TiO2 for the selective catalytic reduction of NH3 in NOx was investigated. The anti-toxicity of Mn-W / TiO2 to different concentrations of SO2 at different temperatures was explored. The results show that WO3 can increase the number and acidity of the active acid sites and is a very effective cocatalyst of MnOx / TiO2. The conversion of NOx to Mn-W / TiO2 was as high as 80.3% -99.6% and the N2 selectivity was 100% ~ 100% when the gas hourly space velocity (GHSV) was 18900h- 98.7%. When the reaction gas has 0.01% SO2 and 6% H2O, the NOx conversion rate at 120 ℃ can be maintained at 98.5%. When the SO2 concentration exceeds 0.01%, the reaction temperature needs to be raised above 250 ℃ to eliminate the interference. When the concentration of SO2 was as high as 0.07%, the conversion rate at 300 ℃ could be maintained at 99% for a long time, which reached the level of commercial VW / TiO2 catalyst. The selective catalytic reduction of NH3 for Mn-W / TiO2 shows excellent catalytic performance and is one of the most toxic catalysts against SO2. It is found that the effect of SO2 on Mn-W / TiO2 catalyst is reversible under low temperature conditions, and the activity will naturally recover as the reaction temperature increases.