采用柠檬酸法合成了BaCeO_3和掺杂Y~(3+)的BaCe_(0.9)Y_(0.9)O_(3-δ)复合氧化物,以Ru_3(CO)_(12)为前体,利用浸渍法制备了Ru/BaCeO_3和Ru/BaCe_(0.9)Y_(0.1)O_(3-δ)催化剂.通过X射线衍射、扫描电镜和透射电镜技术对样品进行了表征,并在固定床反应器中考察了催化剂的氨合成反应活性.结果表明,载体BaCeO_3的稳定性优于BaCe_(0.9)Y_(0.1)O_(3-δ),但Ru/BaCe_(0.9)Y_(0.1)O_(3-δ)催化剂的氨合成活性明显高于Ru/BaCeO_3,在3.0MPa,15 000h~(-1),425℃反应时,Ru/BaCe_(0.9)Y_(0.1)O_(3-δ)催化剂上氨合成反应速率达到432.5ml/(g·h),是Ru/BaCeO_3催化剂的1.6倍.这种活性和稳定性的显著差异来自载体中Ce~(4+)与Ru纳米粒子间的电子作用.
Barium cerate (BaCeO_3) and yttrium-doped barium cerate (BaCe_(0.9)Y_(0.1)O_(3-δ) were synthesized by the citric acid method and used as supports for Ru/BaCeO_3 and Ru/BaCe_(0.9)Y_(0.1)O_(3-δ) catalysts prepared by incipient wetness impregnation using Ru_3(CO)_(12) as precursor. The supports and catalysts were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Their catalytic properties for ammonia synthesis were evaluated in a fixed-bed reactor. The stability of BaCeO_3 was superior to that of BaCe_(0.9)Y_(0.1)0_(3-δ), and the catalytic activity of Ru/BaCe_(0.9)Y_(0.1)O_(3-δ) was higher than that of Ru/BaCeO_3. The rate of ammonia synthesis over Ru/BaCe_(0.9)Y_(0.1)0_(3-δ) was 432.5 ml/(g·h)at 3.0 MPa, 425 ℃, and 15 000 h~(-1), which was 1.6 times higher than that of Ru/BaCeO_3. The electronic interaction between Ce~(4+) and Ru nanoparticles was the key factor for the difference in catalytic activity and stability.
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