SCR脱硝中催化剂表面NH4HSO4生成及分解的原位红外研究

摘要

The mechanism of ammonium bisulfate formation and decomposition over a commercial V2O5-WO3/TiO2catalyst was explored using FT-IR. The results suggest that the formation of ammonium bisulfates mainly occurs in two ways: reaction between activated NH3 adsorbed coordinatedly on Lewis acid sites of catalyst V═O groups and SO2 under atmosphere containing O2;and reaction between absorbed intermediate of metal sulfates VOSO4 and gaseous NH3. NO could react directly with NH+4 in NH4HSO4, which could lower its decomposition temperature, promoting the catalytic decomposition of adsorbed bisulfates (ABS) on catalyst surface. So, there is mutual inhibition between NO removal and ABS formation. Loading of ABS deposited on catalyst surface also affects its decomposition and volatilization.%采用工业用V2O5-WO3/TiO2催化剂，基于傅里叶原位红外光谱(in situ FT-IR)技术考察了SCR脱硝过程中催化剂表面NH4HSO4的生成与分解特性。结果表明：在V2O5-WO3/TiO2催化剂表面ABS的生成可由催化剂V═O基团上Lewis酸上配位吸附活化态的NH3在O2环境中与SO2反应生成，也可由SO2与催化剂表面反应生成的吸附态金属硫酸盐中间物 VOSO4与气态 NH3直接反应生成；NO 能通过与 NH4HSO4中的 NH+4直接反应来降低NH4HSO4降解的温度窗口，促进其在催化剂表面的分解行为，NO 的脱除与 NH4HSO4的生成是相互抑制关系；NH4HSO4本身的负载量影响其分解与挥发行为。