The influence of silicon on the catalytic properties of Cu/SAPO-34 for NOx reduction by ammonia-SCR

• Published in: Applied catalysis. B, Environmental Vol. 127; pp. 137 - 147
• Main Authors: Wang, Jun, Yu, Tie, Wang, Xinquan, Qi, Gongshin, Xue, Junjie, Shen, Meiqing, Li, Wei
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 30-10-2012; Elsevier
• Subjects: Catalysis; Chemistry; Cu/SAPO-34; EPR; Exact sciences and technology; General and physical chemistry; NH3-SCR; NMR; Si content; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Si content; NH3-SCR; NMR; Cu/SAPO-34; EPR; Nitrogen oxide; Scanning electron microscopy; Catalytic reaction; SCR; Acidic site; EPR spectrometry; Ions; NMR spectrometry; Conversion; X ray diffraction; Chemical reduction; Ammonia; Heterogeneous catalysis; Silicon; NH; Catalyst; Low temperature; Environmental protection
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2012.08.016

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► Cu/SAPO-34 performs excellent SCR activity and good hydrothermal stability. ► The contents of Si can directly affect the structure of Cu/SAPO-34 catalysts. ► The Cu loading depends on both the Si contents and the Al contents of HSAPO-34. ► The density of the acidity of Cu/SAPO-34 is affected by the Si contents. ► The Si and Al contents affect the environment of Cu2+ species in Cu/SAPO-34.
The effect of Si content in SAPO-34 on NO selective catalytic reduction over Cu/SAPO-34 catalyst was investigated. Three fresh catalysts with different Si contents, prepared by the same procedure, showed different NO conversions from 120°C to 600°C. These catalysts were characterized in detail by various techniques (ICP, XRD, SEM, NMR, NH3-TPD, H2-TPR and EPR). The NH3-TPD results indicate that the number of acid sites in Cu/SAPO-34 catalyst increases with increasing Si contents and the SCR activities of the samples correlate well with the number of acidic sites at low temperatures (200°C). The EPR and H2-TPR results show that both the Si and the Al contents affect the number of isolated Cu2+ ions in Cu/SAPO-34 catalysts. The catalysts aged at 750°C for 12h showed higher SCR activities than those of the untreated samples, consistent with the higher numbers of the isolated Cu2+ ions.