改性分子筛净化气相中的HCN

以浸渍法制备催化氧化HCN所需催化剂,分别以Ce3+〔Ce(NO₃)₃〕、Fe3+〔Fe(NO₃)₃〕、Cu2+〔Cu(NO₃)₂〕、La2+〔La(NO₃)₂〕为活性组分,以Hβ、HY、5A、ZSM5分子筛作为载体,进行催化剂的优选. 以恒温管式反应器作为反应装置,在250 ℃以下,考察空速、反应温度、φ(O₂)对HCN催化氧化过程的影响以及NO_x的生成率. 结果表明:以0.1 mol/L Cu(NO₃)₂溶液浸渍Hβ分子筛,于300 ℃焙烧所得催化剂Cu/Hβ,在HCN催化氧化过程中具有良好的性能. 在空速低于6 000 h-1、反应温度高于100 ℃时,Cu/Hβ催化剂对HCN的去除率高于95%；反应温度高于200 ℃时,HCN去除率接近100%. 在φ(O₂)由1%增至5%时,HCN去除率高于95%；反应温度低于200 ℃且φ(O₂)小于3%时,NO_x生成率低于5%. 表明铜基改性分子筛催化氧化脱除气相HCN方法所需反应温度低于200 ℃,受φ(O₂)影响小,具有节能、二次污染小的特点. 

Removal of HCN by Modified Molecular Sieve in the Gas Phase

The catalysts used for catalytic oxidation HCN were prepared by the impregnation method. To optimize the catalyst, Ce3+(Ce(NO₃)₃), Fe3+( Fe(NO₃)₃), Cu2+( Cu(NO₃)₂) and La2+(La(NO₃)₂), were used as active components, while molecular sieves including Hβ, HY, 5A and ZSM5 were used as the carrier. The reaction device was a tubular reactor with constant temperature, and effects of space velocity, reaction temperature and O₂ concentration during the HCN catalytic oxidation process were investigated. The formation rate of NO_x was calculated under 250 ℃. The results suggested that Hβ zeolite impregnated with 0.1 mol/L Cu(NO₃)₂ solution and calcinated at 300 ℃ performed well in HCN removal experiments. When the space velocity was under 6000 h-1, the conversion rate of HCN was over 95% above 100 ℃, and the conversion rate reached 100% above 200 ℃. The conversion rate of HCN was higher than 95% when φ(O₂) ranged from 1%-5%. The formation rates of NO_x were less than 5% when the reaction temperature was under 200 ℃ and φ(O₂) was below 3%. The HCN removal method discussed in the present study showed its advantages such as high conversion under 200 ℃, less effect of O₂, low NO_x formation rate less than 5%, energy saving and little secondary pollution.