Pore-structure-control led coagulates of CeO2 nanoparticles for supporting Ru catalysts in liquid phase oxidation of benzyl alcohol
Pore-structure-control led coagulates of CeO2 nanoparticles for supporting Ru catalysts in liquid phase oxidation of benzyl alcohol
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DOI：
10.2109/jcersj2.115.592
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发表时间：
2007-10-01
影响因子：
1.1
通讯作者：
Inoue, Masashi
中科院分区：
文献类型：
--
作者：
Hayashi, Yukihiro;Hosokawa, Saburo;Inoue, Masashi
通过溶剂热反应合成的平均晶粒尺寸为2 nm的CeO 2胶体颗粒用1 mol/L的各种碱溶液（NaOH、NH 4 OH、Na 2CO 3、（NH 4）（2）CO 3、NaHCO 3和NH 4 HCO 3）凝聚。通过在300 ℃下煅烧凝固产物获得的CeO 2粉末具有在4-5 nm范围内的几乎相同的微晶尺寸，而它们的BET表面积显著不同。用Na 2CO 3和NH 4 OH凝聚的CeO 2粉末由于微孔而具有大的表面积，并且使用NaHCO 3和（NH 4）（2）CO 3获得的粉末具有来自大孔的大孔体积。采用沉淀-沉积法制备了一系列Ru/CeO 2催化剂，考察了不同孔结构的CeO 2粉体负载Ru物种在苯甲醇液相氧化反应中的特性。具有良好结晶的RuO 2体相态的Ru物种仅表现出低活性。另一方面，分散良好的Ru物种表现出高活性。CeO 2的孔结构影响Ru物种的负载状态，从而影响它们的氧化活性。钌物种没有负载在微孔内的表面上，通过在这项工作中采用的制备方法。因此，Ru/CeO 2催化剂具有来自介孔和大孔的大表面积，具有分散良好的Ru物种，并显示出高的活性，这是远远高于由常规共沉淀法制备的Ru/CeO 2催化剂。
CeO2 colloidal particles with a mean crystallite size of 2 nm synthesized by a solvothermal reaction were coagulated with 1 mol/L solutions of various bases: NaOH, NH4OH, Na2CO3, (NH4)(2)CO3, NaHCO3, and NH4HCO3. The CeO2 powders obtained by calcination of the coagulated products at 300 degrees C had almost the same crystallite sizes in a range of 4-5 nm, while their BET surface areas were considerably different. The CeO2 powders coagulated with Na2CO3 and NH4OH had large surface areas due to micropores, and the powders obtained using NaHCO3 and (NH4)(2)CO3 had large pore-volumes derived from macropores. A series of Ru/CeO2 catalysts were prepared by a precipitation-deposition method, and characteristics of the Ru species supported on these CeO2 powders having different pore structures were examined in the liquid phase oxidation of benzyl alcohol. The Ru species having well-crystallized RuO2 bulk state showed only low activities. On the other hand, well dispersed Ru species exhibited high activities. The pore structure of CeO2 affected the states of the Ru species loaded, and, consequently, affected their activities for the oxidation. Ruthenium species were not loaded on the surface inside the micropores by the preparation method adopted in this work. Accordingly, the Ru/CeO2 catalysts with large surface areas derived from meso- and macro-pores had well-dispersed Ru species and showed high activities, which were much higher than that of the Ru/CeO2 catalyst prepared by a conventional co-precipitation method.