降低高稀土Y型分子筛制备过程中氮氧化物的排放量

Reducing the nitric oxide emissions in preparation of high rare earth Y zeolite

对高稀土Y型分子筛制备过程中硝酸稀土和铵根对尾气中氮氧化物(NOx)含量的影响进行了分析。结果表明:增大硝酸稀土质量浓度,尾气中NOx质量浓度略有下降,稀土利用率略有增加;将分子筛水筛比[m(水)∶m(分子筛),下同]由7.5∶1.0减小至4.5∶1.0,分子筛中游离态稀土质量分数由5.1%降至4.5%,预交换pH值由3.0提高至4.0,均可降低尾气中NOx质量浓度;在水筛比为5.0∶1.0,预交换pH值为4.0,铵盐加入量[m(铵盐)∶m(硝酸稀土)]为1.00∶4.70的优化体系下,尾气中NOx质量浓度为26.2 mg/m^3。

The effect of rare earth nitrate and ammonium on tail gas nitric oxide(NOx)content were analyzed during the process of high rare earth Y zeolite preparation.The results showed that with the increase of rare earth nitrate mass concentration,NOx concentration in tail gas decreased slightly,utilization rate of rare earth increased slightly;with m(water)/m(zeolite)decreased from 7.5∶1.0 to 4.5∶1.0,mass fraction of rare earths of the zeolite decreased from 5.1%to 4.5%,and prexchange pH value increased from 3.0 to 4.0,tail gas NOx concentration was reduced.Under the optimizing conditions of m(water)/m(molecular sieve)5.0∶1.0,exchange pH value 4.0,the amount of ammonium salt 1.00∶4.70,the exhaust emissions of nitrogen oxides was 26.2 mg/m^3.