C3H6-SCR denitration characteristics of CuCoCe-LDH catalysts
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摘要: 采用水热法一步合成一系列的Cu(x)Co(y)Ce(z)-LDH前驱体，煅烧后形成Cu(x)Co(y)Ce(z)O混合金属氧化物催化剂，在固定床微反应器上实验研究了其C3H6选择性催化还原NO的性能（C3H6-SCR）。得益于Cu、Co、Ce之间强大的协同作用，Cu(0.21)Co(0.48)Ce(0.31)O在225 ℃时达到95%的NO转化率和90%的N2选择性。此外，运用ICP、XRD、TEM、XPS、H2-TPR等表征来研究其物理化学性质和催化还原能力之间的关系。XRD结果表明，Cu、Co、Ce之间形成了固溶体，促进了活性金属的分散。XPS和H2-TPR进一步证明Cu和Co之间发生了氧化还原反应，促进氧空位的形成，从而提升其催化还原性能。
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关键词:
- 氮氧化物 /
- 选择性催化还原 /
- C3H6 /
- CuCoCe-LDH催化剂 /
- 水热法
Abstract: A series of Cu(x)Co(y)Ce(z)-LDH precursors were synthesized by one-step hydrothermal method, and Cu(x)Co(y)Ce(z)O mixed metal oxide catalysts were prepared after calcination and used to study the selective catalytic reduction of NO by C3H6 (C3H6-SCR) with a fixed bed micro-reactor. Due to the strong synergy between Cu, Co and Ce, Cu(0.21)Co(0.48)Ce(0.31)O achieves 95% NO conversion and 90% N2 selectivity at 225 ℃. In addition, ICP, XRD, TEM, XPS, H2-TPR were used to characterize the basic physical-chemical properties of the catalysts to investigate the relationship between physicochemical properties and catalytic reduction abilities. XRD results show that solid solutions are formed between Cu, Co and Ce, which promotes the dispersion of active metals. XPS and H2-TPR further demonstrate that redox reactions occur between Cu and Co, promoting the formation of oxygen vacancies, thereby improving their catalytic reduction capacity.-
Key words:
- nitrogen oxides /
- selective catalytic reduction /
- C3H6 /
- CuCoCe-LDH /
- hydrothermal method
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图 2 不同催化剂的NO转化率(a)、N2选择性(b)和Cu(0.21)Co(0.48)Ce(0.31)O的稳定性测试(c)
Figure 2 NO conversion (a) and N2 selectivity (b) of different catalysts, and stability test of Cu(0.21)Co(0.48)Ce(0.31)O (c)
Reaction conditions: 0.05%NO, 0.1%C3H6, 5%O2, N2 as balance, flow rate=200 mL/min, GHSV=30000 h−1.
图 3 SO2对Cu(x)Co(y)Ce(z)O催化活性的影响(a)及FT-IR谱图(b)
Figure 3 Influence of SO2 on Cu(x)Co(y)Ce(z)O catalysts (a) and FT-IR spectra of Cu(x)Co(y)Ce(z)O (b)
Reaction conditions: 0.05%NO, 0.1%C3H6, 5%O2, 0.02%SO2, N2 as balance, flow rate=200 mL/min, GHSV=30000 h−1.
图 4 Cu(x)Co(y)Ce(z)-LDH前驱体和Cu(x)Co(y)Ce(z)O催化剂的XRD谱图
Figure 4 XRD patterns of Cu(x)Co(y)Ce(z)-LDH precursor and Cu(x)Co(y)Ce(z)O catalysts
图 5 Cu(0.21)Co(0.48)Ce(0.31)-LDH前驱体的TEM图
Figure 5 TEM images (a)−(c) of Cu(0.21)Co(0.48)Ce(0.31)-LDH precursor
图 6 Cu(0.21)Co(0.48)Ce(0.31)O 催化剂的TEM (a)−(b)、EDS mapping (c)−(f)和HRTEM图 (g)−(h)
Figure 6 TEM images (a)−(b), EDS mapping (c)−(f) result of Cu, Co and Ce, and HRTEM images (g)−(h) of Cu(0.21)Co(0.48)Ce(0.31)O catalyst
图 7 Cu(x)Co(y)Ce(z)O催化剂的Cu 2p (a)、Co 2p (b)、Ce 3d (c)和O 1s (d) XPS能谱谱图
Figure 7 XPS energy spectra of Cu 2p (a), Co 2p (b), Ce 3d (c) and O 1s (d) of Cu(x)Co(y)Ce(z)O
图 8 Cu(0.21)Co(0.48)Ce(0.31)O催化剂反应前后的Cu 2p (a)、Co 2p (b)、Ce 3d (c)和O 1s (d) XPS能谱谱图
Figure 8 XPS energy spectra of Cu 2p (a), Co 2p (b), Ce 3d (c) and O 1s (d) before and after the reaction of Cu(0.21)Co(0.48)Ce(0.31)O catalysts
图 9 Cu(x)Co(y)Ce(z)O的N2吸附-脱附等温线和孔径分布
Figure 9 N2 adsorption-desorption isotherms and pore diameter distribution of Cu(x)Co(y)Ce(z)O
图 10 Cu(x)Co(y)Ce(z)O催化剂的H2-TPR谱图
Figure 10 H2-TPR Profiles of Cu(x)Co(y)Ce(z)O catalyst
图 11 Cu(x)Co(y)Ce(z)O催化剂的C3H6-SCR反应机理图
Figure 11 The reaction mechanism of C3H6-SCR over Cu(x)Co(y)Ce(z)O catalyst
表 1 Cu(x)Co(y)Ce(z)O催化剂的表面原子比
Table 1 Atomic concentration on Cu(x)Co(y)Ce(z)O catalyst surface
Catalyst Binding energy/eV Surface atomic ratio/% Cu+ Cu2+ Co2+ Co3+ Cu+/Cu2+ Co2+/Co3+ Ce4+/Ce3+ Oβ/Oα Cu(0.64)Ce(0.36)O 932.4 934.3 − − 0.45 − 3.34 0.72 952.3 954.3 Cu(0.21)Co(0.48)Ce(0.31)O 931.6 933.9 795.8 794.4 0.55 0.46 4.90 0.81 951.3 953.6 781.3 779.6 Co(0.70)Ce(0.30)O − − 794.9 793.6 − 0.77 2.55 0.73 780.7 778.8 
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表 2 Cu(0.21)Co(0.48)Ce(0.31)O催化剂表面原子比
Table 2 Atomic concentration on Cu(x)Co(y)Ce(z)O catalyst surface
Cu(0.21)Co(0.48)Ce(0.31)O Surface atomic ratio/% Cu+/Cu2+ Co2+/Co3+ Ce4+/Ce3+ Oβ/Oα Before 0.55 0.46 4.90 0.81 After 0.47 0.47 4.27 0.65
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表 3 Cu(x)Co(y)Ce(z)O催化剂的比表面积、孔容、孔径及ICP数据
Table 3 Specific surface area, pore volume, pore size and ICP data of Cu(x)Co(y)Ce(z)O catalyst
Catalyst ABET/
(m2·g−1)vP/
(cm3·g−1)dP/
nmElement content/(mg·g−1) Molar ratio Cu Co Ce x y z Cu(0.64)Ce(0.36)O 80 0.060 6.566 287.32 − 353.54 0.64 − 0.36 Cu(0.31)Co(0.36)Ce(0.33)O 59 0.170 10.328 141.93 151.94 330.50 0.31 0.36 0.33 Cu(0.21)Co(0.48)Ce(0.31)O 53 0.125 11.670 100.75 212.29 325.33 0.21 0.48 0.31 Co(0.70)Ce(0.30)O 29 0.123 14.853 − 329.03 329.01 − 0.70 0.30
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