研究目的
To use UV–vis spectroscopy to identify the correlations between H2-TPR peaks and different Cu species in Cu–SAPO-34, as well as the distinction of Cu species with the different Cu loading amounts.
研究成果
Cu–SAPO-34 catalysts with controlled Cu contents were successfully prepared using the impregnation–activation method, retaining the CHA structure and physical properties. UV–vis and H2-TPR analysis identified three types of copper species: isolated Cu2+ ions balanced by two framework charges (dominant at ≤0.8 wt% Cu), isolated Cu2+ ions balanced by one charge (at higher loadings), and bulk CuO (at very high loadings). This provides a method for quantitative control and identification of copper species, important for optimizing NH3-SCR catalysts.
研究不足
The preparation includes a lengthy calcination process. The method may not fully avoid framework damage compared to other synthesis methods, and the assignments of H2-TPR peaks, particularly the β peak, are based on correlations and may have uncertainties. The study is limited to Cu–SAPO-34 and may not be directly applicable to other zeolitic materials.
1：Experimental Design and Method Selection:
Cu–SAPO-34 catalysts with various copper loadings (0.4, 0.8, 1.6, and 3.2 wt%) were prepared using impregnation followed by activation via high-temperature calcination (impregnation–activation method). Characterizations included XRD, N2 physisorption, UV–vis spectroscopy, H2-TPR, NH3-TPD, and NH3-SCR activity tests to analyze copper species and properties.
2：4, 8, 6, and 2 wt%) were prepared using impregnation followed by activation via high-temperature calcination (impregnation–activation method). Characterizations included XRD, N2 physisorption, UV–vis spectroscopy, H2-TPR, NH3-TPD, and NH3-SCR activity tests to analyze copper species and properties.
Sample Selection and Data Sources:
2. Sample Selection and Data Sources: Commercial H–SAPO-34 powder (Süd Chimie, Germany; Al/Si/P = 1.0/0.15/0.85) was used as the support. Copper acetate solution (>99%; Sinopharm Chemical Reagents, China) was the copper source. Samples were denoted as Cu04, Cu08, Cu16, Cu32 based on target Cu loadings.
3：0/15/85) was used as the support. Copper acetate solution (>99%; Sinopharm Chemical Reagents, China) was the copper source. Samples were denoted as Cu04, Cu08, Cu16, Cu32 based on target Cu loadings.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment included ICP-OES (Agilent 5100), XRD (Bruker D8 Advance), N2 physisorption analyzer (JW-BK122F), UV–vis spectrophotometer (UV-2600), H2-TPR instrument (Chem II 2920), FT-IR spectrometer (Nicolet 380), and FT-IR gas analyzer (MKS Multigas? 2030). Materials included BaSO4 for UV–vis standards, gases (He, H2/Ar, O2/N2, NH3, NO), and catalysts.
4：0). Materials included BaSO4 for UV–vis standards, gases (He, H2/Ar, O2/N2, NH3, NO), and catalysts.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Impregnation was done by mixing H–SAPO-34 with copper acetate solution, drying at 110°C for 12h, and calcining at 750°C for 24h. Characterizations involved specific pretreatments: e.g., for H2-TPR, samples were pretreated in He at 200°C for 30min, then reduced in 10% H2/Ar from 0 to 700°C. UV–vis of prereduced samples involved stopping H2-TPR at specific temperatures and transferring to UV–vis chamber. NH3-TPD and SCR tests were performed in a flow reactor with temperature ramps and gas concentration monitoring.
5：4h. Characterizations involved specific pretreatments:
5. Data Analysis Methods: Copper content was measured by ICP-OES. XRD patterns were analyzed for crystal structure. Surface areas and pore volumes were calculated from N2 physisorption data. UV–vis spectra were converted using Kubelka–Munk formula. H2-TPR peaks were deconvoluted and assigned based on reduction temperatures. NH3-TPD curves were analyzed for acidity. NOx conversions in SCR were calculated from inlet and outlet gas concentrations using FT-IR detection.
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