不飽和烴之氧化 第三報 乙烯之觸媒氧化試製環氧乙烷

The Oxidation of Olefins. III. The Direct Air Oxidation of Ethylene

10.6623/chem.1963015

任騰閣(Tang-Ke Jen)

化學

52年3期（1963 / 09 / 01）

95 - 102

繁體中文

在不同反應條件下，使用八種銀觸媒進行乙烯之直接氧化，以比較各種觸媒之接觸效能。由實驗結果得知：觸媒21號（Ag_2O:BaO_2:alundum SA203=34.2:7:200）及22號（Ag_2O:BaO_2:alundum SA103=34.2:7:200）具有較高效能；前者之最佳反應條件爲空氣乙烯體積比25：1，預熱溫度200℃，反應溫度250°C，接觸時間2.5秒，可得最高乙烯轉化率44.9%及環氧乙烷生成率56.1%；後者在反應溫度200°C，接觸時間1.1秒下，所得各爲45.2%及64.5%。

There are, as we know, two processes for manufacturing ethylene oxide from ethylene; one is through chlorination and the other through direct oxidation with air using a certain kind of silver catalyst. This paper is to present our study on a new silver catalyst of high activity and high yield, prepared in a different way. The silver catalyst used in the oxidation process usually consists of three components: silver oxide, promotor and carrier. In this study we generate silver oxide with a new method, while the promotors used are sodium carbonate, cobalt acetate, silver carbonate or barium peroxide as in the usual practice and employ firebrick grains, artificial purmicestone and fused α-alumina (namely, alundum SA103, alundum SA104, alundum SA203, marketed by Norton Co., U. S. A.) as carriers. Being different from the conventional method of preparing silver oxide from silver nitrate and barium or alkali hydroxide, our new method of preparation consists of two steps; (1) generating silver oxalate from silver nitrate and oxalic acid and then (2) preparing silver oxide from the oxalate and barium peroxide. The reactions may be represented as follows: 2AgNO_3 + H_2C_2O_4 → Ag_2C_2O_4 + 2HNO_3 Ag_2C_2O_4 + BaO_2 → Ag_2O + BaC_2O_4 + 1/2 O_2 O_□ the eight catalysts employed in t his study, it has been found that ＂No. 21＂ and ＂No. 22＂ are the most effective ones. They have almost the same compositions, namely Ag_2O:BaO_2:alundum=34.2:7:200, the only difference between them lies in the carriers, the former using alundum SA203 and the latter using alundum SA103. The conditions for maximum yields are tabulated in the following table: (The form abridges) The effectiveness of the two catalysts, as we are led to assume, should be attributed to the silver oxide made by the new method and the choice of alundum SA203, 103 as carriers. This is the third of a series of papers devoted to a thorough study of the olefins. In the first paper we presented our findings, on the reactor of a glass tube of 1/2＂ diameter with catalyst ＂No. 11＂, as 31% for the conversion of ethylene and 46% for the yield or ethylene oxide. In the second study we used mild steel tube of 3/4＂ diameter as reactor and got best results with catalyst ＂New No. 20＂, which were 30.4% for the conversion of ethylene and 53.8% for the yield of ethylene oxide. In the present investigation we employed a reactor of mild steel tube of larger diameter 11/2＂, and got best results with catalysts ＂No. 21＂ and ＂No. 22＂, which were 44.9%, 56.1%, and 45.2%, 64.5% respectively, as indicated in the above table.