催化作用
氮氧化物
热液循环
选择性催化还原
沸石
结晶
吸附
化学
无机化学
水热合成
化学工程
大气温度范围
材料科学
有机化学
燃烧
物理
气象学
工程类
作者
Xiaofeng Wang,Yang Xu,Mengyue Qin,Qingbo Li,Xinhua Liu
标识
DOI:10.1016/j.jece.2023.110840
摘要
Cu-SAPO-18 catalysts attracts increasing attention in the reaction of selective catalytic reduction (SCR) of nitrogen oxides (NOx), but the catalyst synthesis process is complicated and time-consuming. Also, it is urgent to enhance the low-temperature catalytic conversion of NOx for practical applications. Herein, we reported a fast-synthesis method to prepare the Cu-SAPO-18 catalysts in 32–80 h, and the catalysts showed an excellent catalytic performance of over 80 % NO conversion at 260–480 °C. The crystalline of the catalysts was improved in short crystallization time and high crystallization temperature, accelerating the NH3-SCR reaction. The low-temperature activity of all catalysts was improved after hydrothermal treatment, and the temperature range of over 80 % NO conversion was extended to 190–515 °C for the optimized catalyst, which was due to the increasing active Cu2+ species (ZCuOH and Z2Cu, where Z represents an anionic site on the zeolite framework). The redox cycle of Cu2+/Cu+ was accelerated and more Lewis acid sites on the catalyst enhanced the NO/NH3 adsorption and activation, promoting the low-temperature catalytic activity. Furthermore, after hydrothermal treatment, part of Z2Cu species converted to ZCuOH species, which exhibited stronger NO adsorption energies (−2.06 eV) than that of Z2Cu (−1.38 eV) based on theoretical calculation. Both fresh and aged catalysts showed remarkable SO2/H2O resistance. This work reveals the effects of hydrothermal treatment on the Z2Cu and ZCuOH species, which is helpful to prepare the fast-synthesized zeolite catalysts with excellent low-temperature SCR performance.
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