Electrocatalytic synthesis of propylene oxide during water electrolysis
Electrocatalytic synthesis of propylene oxide during water electrolysis
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水电解电催化合成环氧丙烷
DOI：
10.1006/jcat.1995.1310
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发表时间：
1995
影响因子：
7.3
通讯作者：
K. Ebitani
中科院分区：
文献类型：
--
作者：
K. Otsuka;T. Ushiyama;I. Yamanaka;K. Ebitani
提出了一种利用水电解过程中产生的初生氧合成环氧丙烷的新方法。在测试的贵金属黑中，最具活性和选择性的阳极电催化剂是铂黑。丙烯的氧化在电池上施加的电压高于约100V时开始。 1.1 V（阳极电位高于 1.1 V vs NHE）。在>1.1V的施加电压下，环氧丙烷和丙酮的形成显着增强。在施加电压为 1.5 V 时（阳极电位 1.3 V vs NHE），两种产物的最大氧化效率为 56%。在高于1.5 V的施加电压下的环氧化增强了副产物CO{sub 2} {ge}乙酸-丙酸的形成。每种产物的动力学曲线表明环氧丙烷和丙酮是平行形成的；所产生的环氧丙烷不会形成丙酮、CO{sub 2} 或乙酸。该方法对于 1-己烯以及顺式和反式 2-己烯的环氧化更有效。对于2-己烯的环氧化观察到的顺式-和反式-2,3-环氧己烷的产物比表明起始2-己烯的顺式-反式构型的保留。用同样的方法氧化环己烷和更多的苯非常缓慢，产生 CO{sub 2} 作为主要产物。因此，该系统中产生的活性氧对于烯烃的环氧化是非常特定的。不活泼的铂黑在空气中在约 100 ℃下煅烧。 673 K显着增强了其对烯烃环氧化的电催化活性。对各种 Pt 黑样品的 XPS 研究表明，PtO{sub 2} 相是活性氧形成的原因。已经提出了一种尝试性的 Langmuir-Hinshelwood 型反应机理来解释环氧化结果。 31 条参考文献，11 个图，2 个标签。« 更少
A new method for the synthesis of propylene oxide using nascent oxygen generated during the electrolysis of water has been proposed. Among the noble metal blacks tested, the most active and selective anode electrocatalyst was Pt black. The oxidation of propylene was initiated at an applied voltage across the cell higher than ca. 1.1 V (anode potential higher than 1.1 V vs NHE). The formations of propylene oxide and acetone were enhanced remarkably at >1.1 V applied voltage. The maximum oxidation efficiency for the sum of the two products was 56% at an applied voltage of 1.5 V (anode potential 1.3 V vs NHE). The epoxidation at applied voltage higher than 1.5 V enhanced the formation of by-products, CO{sub 2} {ge} acetic acid - propionic acid. The kinetic curves of each product suggest that propylene oxide and acetone are formed in parallel; neither acetone, nor CO{sub 2}, nor acetic acid are formed from the propylene oxide produced. The method was more effective for epoxidations of 1-hexene and cis- and trans-2-hexenes. The product ratio in cis- and trans-2,3-epoxyhexanes observed for the epoxidations of the 2-hexenes indicated the retention of the cis-trans configuration of the starting 2-hexenes. The oxidations of cyclohexane andmore » benzene by the same method were quite slow, giving CO{sub 2} as the main product. Thus, the active oxygen generated in this system was quite specific for epoxidation of olefins. The calcination of an inactive Pt black in air at ca. 673 K enhanced remarkably its electrocatalytic activity for epoxidation of olefins. XPS studies on various Pt black samples suggested that the PtO{sub 2} phase was responsible for the formation of the active oxygen. A tentative Langmuir-Hinshelwood-type reaction mechanism has been proposed to account for the epoxidation results. 31 refs., 11 figs., 2 tabs.« less