Au NP‐catalysed Propene Epoxidation by Dioxygen and Dihydrogen
Au NP‐catalysed Propene Epoxidation by Dioxygen and Dihydrogen
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Au NP 催化的分子氧和分子氢的丙烯环氧化反应
DOI：
10.1002/9783527621323.ch14
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
M. Haruta
中科院分区：
文献类型：
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作者：
J. Kawahara;M. Haruta
环氧丙烷（PO，IUPAC命名：2-甲基环氧乙烷）是一种重要的化工原料，全球年生产能力约为700万吨[1]。它被加工成主要产品聚氨酯多元醇和丙二醇[2]。前者用于制造聚氨酯泡沫，后者用于防冻剂（比乙二醇更安全）、药品、化妆品等。目前工业上用于生产PO的主要有氯醇法和有机氢过氧化物法两条路线。这两者都由两个反应阶段组成，并伴随着副产物和副产物的形成[3]。 2003 年，住友化学有限公司在日本千叶县启动了一座产能为 150 000 ty−1 的新商业工厂，该工厂采用有机氢过氧化物工艺与异丙苯回收相结合（方案 14.1）。该过程除了消耗分子氧 (O 2) 之外还消耗分子氢气 (H 2)，但不产生除水 (H2o) 以外的副产品。他们最初的介孔硅酸钛用作环氧化阶段的催化剂[4, 5]。另一方面，BASF/Dow 和 Degussa/Uhde 分别在比利时和韩国采用过氧化氢 (H2o 2) 环氧化作为建设新商业工厂的基础，计划于 2008 年投产 [1]。 Degussa/Uhde 使用钛硅石作为催化剂，在甲醇 (MeOH) 溶剂中用 H2o 2 环氧化丙烯 (C3h 6, 丙烯) [6, 7]（方案 14.1）。因此，PO生产的下一个目标将转向单独使用O 2 或更可行地使用O 2 和H 2 直接环氧化（方案14.2）。 C3h 6 与O 2 直接环氧化是最难实现的反应之一，被视为催化研究中的“圣杯”。氧化丙烯比丙烯更具反应性。与乙烯相反，C3h 6 具有烯丙基 C− H 键，其强度在分子中最低，导致甲基优先脱氢 [8]。此外，当分子氧吸附在固体表面上时，它往往会变成阴离子物质，例如O 2− 或O− 。由于这些带负电的氧本质上是亲核的，它们攻击甲基中的碳原子，从而产生
Propene oxide (PO, IUPAC nomenclature: 2-methyloxirane) is an important chemical feedstock, having a world annual production capacity of about 7 million tons [1]. It is processed into the major products, polyurethane polyols and propylene glycol [2]. The former are used in the manufacture of polyurethane foams and the latter for antifreeze (safer than ethylene glycol), drugs, cosmetics etc. Currently there are two major routes, the chlorohydrin process and the organic hydroperoxide process, employed industrially for the production of PO. Both of these consist of two reaction stages, and are accompanied by the formation of byproducts and co-products [3]. In 2003, Sumitomo Chemical Co., Ltd. launched a new commercial plant of 150 000 ty− 1 capacity, in Chiba prefecuture, Japan, that uses an organic hydroperoxide process combined with cumene recycling (Scheme 14.1). This process consumes dihydrogen (H 2) in addition to dioxygen (O 2) but is free from co-products other than water (H2o). Their original mesoporous titanium silicate is used as a catalyst for the epoxidation stage [4, 5]. On the other hand, epoxidation with hydrogen peroxide (H2o 2) has been adopted as the basis for the construction of new commercial plants by BASF/Dow and Degussa/Uhde, in Belgium and Korea, respectively, which are planned to come on stream in 2008 [1]. Degussa/Uhde uses titanosilicalite as a catalyst for the epoxidation of propene (C3h 6, propylene) with H2o 2 in methanol (MeOH) solvent [6, 7](Scheme 14.1). Accordingly, the next target for PO production will shift to the direct epoxidation with O 2 alone or more feasibly with O 2 and H 2 (Scheme 14.2). The direct epoxidation of C3h 6 with O 2 alone is one of the most difficult reactions to achieve and is regarded as a sort of “Holy Grail” in catalysis research. Propene oxide is more reactive than propene. In contrast to ethene, C3h 6 has allylic C− H bonds, the strength of which is the lowest in the molecule causing preferential dehydrogenation of the methyl group [8]. Furthermore, when molecular oxygen adsorbs on solid surfaces it tends to become an anionic species such as O 2− or O−. Since these negatively charged oxygen species are nucleophilic in nature, they attack the carbon atom in the methyl group resulting in the production of