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用EPR谱法对铜基甲醇合成催化剂作表征。结果表明:在少量Al ̄(3+)掺杂的ZnO-Al_2O_3体系可检测到g=1.9606±0.0002,△Hpp=2.8G的顺磁信号,其强度随Al_2O_3掺杂量增加而增强,当Al/Zn~2/100(原子比)时趋于峰值;而在三组份Cu-ZnO-Al_2O_3和四组份Cu-ZnO-Al_2O_3-Sc_2O_3催化剂体系中,此顺磁信号基本消失。以上结果为三价金属离子(Al ̄(3+)、Sc ̄(3+))在ZnO晶格掺杂诱生正一价缺位从而有利于Cu以+1价态存在的观点,提供了新证据。
Characterization of copper-based methanol synthesis catalysts by EPR spectroscopy. The results show that the paramagnetic signals of g = 1.9606 ± 0.0002 and △ Hpp = 2.8G can be detected in a small amount of Al 3+ doped ZnO-Al 2 O 3 system with the intensity increasing with the amount of Al 2 O 3 doping , And peaked at Al / Zn ~ 2/100 (atomic ratio). However, the paramagnetic signal disappeared in the three component Cu-ZnO-Al_2O_3 and four component Cu-ZnO-Al_2O_3-Sc_2O_3 catalyst systems . The above results provide new evidences that the trivalent metal ions (Al ~ (3 +), Sc ~ (3 +)) induce lattice defects at the positive one due to the ZnO lattice doping and thus favor the presence of Cu in the +1 state.