Conversions of some small organic compounds with metal oxides in supercritical water at 673 K
Conversions of some small organic compounds with metal oxides in supercritical water at 673 K
复制标题
一些小有机化合物在 673 K 超临界水中与金属氧化物的转化
DOI：
10.1039/b304686a
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发表时间：
2003
期刊：
影响因子：
9.8
通讯作者：
K. Arai
中科院分区：
文献类型：
--
作者：
Masaru Watanabe;Toru Iida;Y. Aizawa;H. Ura;H. Inomata;K. Arai
采用间歇式反应器，在673 K和25-35 MPa的超临界水中，以甲醛（HCHO）、乙酸（CH 3COOH）、2-丙醇（2-PrOH）和葡萄糖为原料，分别与CeO 2、MoO 3、TiO 2和ZrO 2等金属氧化物进行反应。对于甲醛的反应，CeO_2和ZrO_2表现出碱性，而MoO_3和TiO_2则表现出酸性。ZrO 2催化剂促进了CH 3COOH的双分子脱羧反应生成丙酮，表明在超临界水中ZrO 2表面同时存在酸碱中心。酸催化剂（H_2SO_4）促进2-PrOH脱水生成丙烯，碱催化剂（NaOH）促进2-PrOH脱氢生成丙酮。在本研究中使用的所有金属氧化物促进2-PrOH的脱水;即在所使用的条件下，在所有金属氧化物的表面上主要存在用于2-PrOH反应的酸性位点。在金属氧化物中，ZrO 2和TiO 2
（金红石）增强了2-PrOH反应中丙酮的生成。这意味着在ZrO 2和TiO 2上也存在2-PrOH的碱性位点
（金红石）。在673 K和15 min的超临界水中，在酸性气氛中（即在H2SO 4存在下）葡萄糖的H2产率低于在没有添加剂的情况下的H2产率，而另一方面，在NaOH存在下的H2产率是在没有添加剂的情况下的H2产率的两倍。使用CeO 2和ZrO 2时，葡萄糖的H2产率几乎是没有催化剂时的两倍。通过添加MoO 3和TiO 2，抑制了H2的生成量。通过本研究，我们可以看出金属氧化物在超临界水中有机反应中的酸碱性的普遍性。
Reactions of formaldehyde (HCHO), acetic acid (CH3COOH), 2-propanol (2-PrOH), and glucose with some metal oxides (CeO2, MoO3, TiO2, and ZrO2) were conducted in supercritical water at 673 K and 25–35 MPa, using batch reactors. For the reactions of HCHO, CeO2 and ZrO2 showed basicity, on the other hand, MoO3 and TiO2 were acid catalysts. ZrO2 catalyst promoted bimolecular decarboxylation of CH3COOH to form acetone, which indicates that both acid and base sites exist on the surface of ZrO2 in supercritical water. Dehydration of 2-PrOH with formation of propylene was promoted by acid catalyst (H2SO4), while its dehydrogenation with formation of acetone was catalyzed by alkali (NaOH). All the metal oxides that were used in this study promoted dehydration of 2-PrOH; namely there are mainly acidic sites for 2-PrOH reactions on the surface of all the metal oxides under the conditions used. Among the metal oxides, ZrO2 and TiO2
(rutile) enhanced the formation of acetone in the case of 2-PrOH reaction. This means there are also basic sites for 2-PrOH on the ZrO2 and TiO2
(rutile). In supercritical water at 673 K and 15 min, H2 yield from glucose in the acidic atmosphere (namely in the presence of H2SO4) is lower than that in the absence of additive whereas, on the other hand, the H2 yield in the presence of NaOH is twice as much as that in the absence of the additive. With CeO2 and ZrO2, the H2 yield from glucose was almost twice as high as that without catalyst. By adding MoO3 and TiO2, the amount of H2 formation was suppressed. Through this study, we can show the generality of acidity and basicity of the metal oxides for organic reactions in SCW.
影响因子：
4.2
作者：
B. M. Kabyemela;T. Adschiri;R. Malaluan;K. Arai;H. Ohzeki
通讯作者：
B. M. Kabyemela;T. Adschiri;R. Malaluan;K. Arai;H. Ohzeki