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负载型含钌催化剂的制备及其对水煤气变换催化作用

Preparation and Properties of Supported Ruthenium-contained Catalyst for Water-gas Shift Reaction

【作者】 王海涛

【导师】 杨平; 华南平;

【作者基本信息】 苏州大学 , 物理化学, 2005, 硕士

【摘要】 采用溶胶法将变换催化剂的活性组份制成单一或复合纳米粒子,然后负载到高比表面的镁铝尖晶石载体上。活性组分负载以后,具有很高的分散度,不仅比传统催化剂有更高的催化活性,而且抗团聚和烧结能力增强,提高了催化剂的耐热性能和使用寿命。 通过XRD、TEM、DSC-DTG、BET等测试手段对催化剂样品进行表征。实验结果表明:虽然钌能够作为活性中心直接催化变换反应,但其主要作用是作为电子助剂促进电子交换;助剂氧化镧不能进入Fe3O4晶格,主要起到电子助剂的作用;采用NaBH4还原法制备的催化剂,由于钌纳米颗粒表面吸附有硼物种,在相同的反应条件下,活性要低于由乙二醇还原法制备的催化剂。在相同反应条件下,活性组分Ru的颗粒尺寸越小,催化活性越好,催化剂起活温度越低;复合纳米粒子催化剂由于核对壳层的电子效应,表现出比单一纳米粒子催化剂更为优越的催化性能,具有起活温度低,低温活性好等优点。 负载型变换催化剂FRL/MA-2在保持活性与铁铬催化剂(B117)相当的同时,去除了对环境有毒害的氧化铬,在低汽气比和高空速条件下运行良好,与工业催化剂B117相比,具有更好的耐热性能;负载型钌基交换催化剂R/MA-5和RL/MA-3在汽气比为1,空速2000h-1的反应条件下,CO的转化率在350℃时达到了100%,300℃时达到85%以上,具有良好的工业应用前景:负载型复合纳米粒子催化剂Fe2O3-Ru/MA起活温度低(120℃),CO的转化率在300℃时就已经达到97.4%(S/G=1,SV=2000h-1),对研制新颖用途的水煤气变换催化剂,如用于燃料电池电动车的水煤气变换催化剂,具有很好的借鉴意义和参考价值。

【Abstract】 In this thesis, a series of supported catalysts for water-gas shift (WGS) reaction was prepared by loading active species on the supporters (MgAl2O4 spinel) with large specific surface area. The supported catalysts manifest high catalytic activity and better thermal stability than traditional catalysts due to the high dispersion of active species.The properties of supported WGS catalysts have been studied by using XRD, TEM, and DSC-TGA etc. The results show that lanthanum oxide cannot enter the lattice of Fe3O4, and act as electronical promoters. The preparation method of ruthenium nanoparticles has great effect on catalytic activity of supported ruthenium catalysts, sample prepared from ethylene glycol reduction have superior activity to sample prepared by NaBH4 reduction. And the smaller the size of ruthenium nanoparticles, the better catalytic activity and the lower light-off temperature obtained. Catalysts prepared from composite nanoparticles have higher catalytic activity than supported only ruthenium catalysts, due to electronical effect the core to the shell.Catalyst FRL/MA-2 have the same activity as commercial Fe-Cr WGS catalysts B117 and better thermal stability; Catalysts R/MA-5and RL/MA-3 have high activity, CO conversion of ≥85% (at 350℃, S/G=1, SV=2000h-1) were obtained. And they can be performed well under low steam/gas ratio and high space velocities conditions. Catalysts Fe2O3-Ru/MA prepared from composite nanoparticles show low light-off temperature (120 V) and high catalytic activity on WGS reaction, CO conversion of ≥97.4% (at 300℃, S/G=1, SV=2000h-1) were obtained.

  • 【网络出版投稿人】 苏州大学
  • 【网络出版年期】2006年 05期
  • 【分类号】O643.36
  • 【被引频次】4
  • 【下载频次】459
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