乙苯催化氧化脱氢合成苯乙烯的研究

Catalytic Oxidative Dehydrogenation of Ethylbenzene to Styrene

研究了Ｖ－Ｍｇ－Ｏ系催化剂的组成对乙苯氧化脱氢制苯乙烯的催化活性的影响。试验结果表明，Ｖ＿２Ｏ＿５的含量有一适宜的范围，加入适量第三组份Ｋ＿２Ｏ、ＣｏＯ、ＺｎＯ或稀土元素的氧化物能改善催化剂的氧化脱氢活性，其中稀土氧化物的引入，效果尤为显著。由ＸＲＤ对晶相组成的测试结果发现，引入稀土氧化物后有新晶相Ｍｇ＿２Ｖ＿２Ｏ＿７生成。研究了在Ｖ－Ｍｇ－稀土－Ｏ催化剂上乙苯氧化脱氢反应条件的影响。在５００℃、常压、乙苯重量空速１．５ｈ￣（－１）、乙苯：Ｏ＿２：Ｎ＿２：Ｈ＿２Ｏ为１：１．２：２０：８（ｍｏｌ）的条件下，乙苯转化率达７６％，苯乙烯收率达６７％。

The effect of V- Mg-O catalyst composition on activities and selectivities in oxidativedehydrogenation of ethylbenzene to styrene was investigated.It is found that the content of V_2O_5 in V-Mg-Ocatalysts has a proper value,and the addition of proper amount of K_2O,CoO,ZnO or oxide of rare earth element can improve their activities.It is found by XRDanalysis that highly dispersed Mg_3V_2O_8 fine crystals are the more active phase of the cata-lyst, and the presence of proper amount of Mg_2V_2O_7 crystals can obviously improve its acti-vity. The effect of reaction conditions on X-26 catalyst was also studied.Under the suitablereaction conditions : 500℃, weight space velocity of ethylbenzene 1.5h￣(-1), EB : O_2:N_2:H_2O=1:1.2 :20 : 8(mol ),the conversion of ethylbenzene reaches 76%,and the selectivity ofstyrene reaches 88%.