Novel synthesis of fly-ash-derived Cu-loaded SAPO-34 catalysts and their use in selective catalytic reduction of NO with NH3

• 作者: Baodong Wang Daojun Zhang Ge Li Hongyan Wang Jiali Zhou Qi Sun Wayne Qiang Xu Ziran Ma
• 来源期刊: 绿色能源与环境:英文版
• 学科: 化学
• 关键词: Fly-ash-derived SAPO-34 LOW-TEMPERATURE NH3-SCR Cu/SAPO-34 CU content CU species
• 年，卷（期）: 2019,（4）
• 页码范围: 470-482
• 页数: 13页
• 分类号: O64

摘要

A combined acid–alkali hydrothermal method was used to prepare fly ash–derived SAPO-34 molecular sieves from a thermal power plant in Inner Mongolia(China).The specific surface area of the prepared fly-ash-derived SAPO-34 molecular sieves was 579 m^2 g^-1,the total pore volume was about 0.27 cm^3 g^-1,and the pore size was 0.56 nm;the molar ratios of Al2O3:P2O5:SiO2 were 1:0.86:0.45.Cu/SAPO-34 catalysts were prepared by impregnation of low-cost fly-ash-derived SAPO-34 molecular sieves as a support and tested in selective catalytic reduction with NH3(NH3-SCR).Powder X-ray diffraction(XRD),N2 adsorption–desorption,X-ray photoelectron spectroscopy(XPS),H2 temperatureprogrammed reduction(H2-TPR),NH3 temperature-programmed desorption(NH3-TPD),electron paramagnetic resonance(EPR),nuclear magnetic resonance(NMR),X-ray fluorescence analysis(XRF)and scanning electron microscopy(SEM)were used for catalyst characterization and investigation of the relationships between the catalyst structure and the catalytic activity.The actual silica:alumina ratio of the molecular sieves did not increase with increasing Cu loading,indicating that increasing the Cu loading does not change the original structure of the SAPO-34 molecular sieves.The XRF and NMR results showed that replacement by Cu results in more Si islands.The molecular sieve acidity decreased because of the increased number of Si islands.The NH3-TPD results showed that for the Cu/SAPO-34 catalysts there was a low correlation between the low-temperature activity and the amount of acidic sites.SCR activity is closely related to the location of Cu.The 4.47 Cu/SAPO-34 catalyst has the highest isolated Cu2+showed the highest NH3-SCR activities(>90%)at 250–350℃.This work opens up new avenues for recycling fly ash formed in coal-fired power plants(reducing environmental pollution)and developing low-cost SCR catalysts for NOx pollution control.