Acta Chimica Sinica ›› 2021, Vol. 79 ›› Issue (3): 361-368.DOI: 10.6023/A20100478 Previous Articles    



张雅祺1, 楚奇1, 石勇1,*(), 高金索1, 熊巍1, 黄磊1, 丁越1   

  1. 1 大连理工大学环境学院 工业生态与环境工程教育部重点实验室和精细化工国家重点实验室 大连 116024
  • 投稿日期:2020-10-22 发布日期:2020-12-05
  • 通讯作者: 石勇
  • 作者简介:
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  • 基金资助:

Synthesis of Bimetallic Ag-Ni-MOF-74 Catalyst with Excellent CO-SCR Performance in Low Temperature Range

Yaqi Zhang1, Qi Chu1, Yong Shi1,*(), Jinsuo Gao1, Wei Xiong1, Lei Huang1, Yue Ding1   

  1. 1 School of Environmental Science and Technology, Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
  • Received:2020-10-22 Published:2020-12-05
  • Contact: Yong Shi
  • Supported by:
    National Natural Science Foundation of China(21677022)

Selective catalytic reduction of NOx with CO technology (CO-SCR) is supposed to be a cost-effective and environmentally friendly technique for NOx abatement in the flue gas under CO-rich conditions. As a promising class of porous hybrid inorganic-organic materials, bimetallic metal-organic frameworks exhibit great physicochemical properties in catalysis area, whereas their application in low-temperature CO-SCR system are seldom reported. In this study, a series of bimetal organic-frameworks catalysts with different Ag contents were successfully prepared by a post-synthesis method and were assessed for NO reduction by CO. The typical experimental procedure for the synthesis of bimetallic Ag-Ni-MOF-74 catalysts is as follows: First, a light yellow Ni-MOF-74 sample was prepared by a hydrothermal method. Then 250 mg Ni-MOF-74, 1 mmol of NaBH4 and AgNO3 with different molar ratio (0.25, 0.5, 1 mmol) were added into 40 mL N,N-dimethylformamide (DMF) solution, and were stirred for 6 h. The mixtures were further moved into a Teflon-lined autoclave at 150 ℃ for 12 h. After washing with DMF and methanol, the obtained Agx-Ni-MOF-74 catalysts were dried at 60 ℃ under vacuum for 12 h. Totally, bimetallic Ag-Ni-MOF-74 catalysts exhibited a better low-temperature CO-SCR efficiency than monometallic Ni-MOF-74 catalysts. Especially, Ag1-Ni-MOF-74 achieved a nearly 100% NO conversion in the temperature range from 200 ℃ to 300 ℃. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature programmed reduction (H2-TPR) techniques were used to investigate the structure and properties of the samples. It was found that Ag addition not only enriched the form of more active sites, but also increased the specific surface area of the catalysts, which promote the activation and transfer of reactants. The synergistic effect between Ag and Ni species also contributed to enhancement of surface oxygen vacancies and accelerated the electron transfer in NO+CO reaction. By combining XPS and in situ FT-IR results, the mechanism of CO-SCR reaction over Ag-Ni-MOF-74 was proposed to follow Langmuir- Hinshelwood (L-H) mechanism, which exhibits a more readily low-temperature reaction rate and a lower reaction barrier than Eley-Rideal (E-R) mechanism.

Key words: denitration, bimetallic MOFs, Ag-Ni-MOF-74, post synthetic modification, CO-SCR