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首页> 外文期刊>Catalysis science & technology >Oxidative dehydrogenation of ethyl benzene to styrene over alumina: effect of calcination
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Oxidative dehydrogenation of ethyl benzene to styrene over alumina: effect of calcination

机译：乙烯对苯乙烯的氧化脱氢作用：钙化的影响

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Commercially available γ-Al2O3 was calcined at temperatures between 500 and 1200 °C and tested for its performance in the oxidative ethylbenzene dehydrogenation (ODH) over a wide range of industrially-relevant conditions. The original γ-Al2O3, as well as t|- and α-Al2O3, were tested. A calcination temperature around 1000/1050 °C turned out to be optimal for the ODH performance. Upon calcination the number of acid sites (from 637 to 436 nmol g~(-1)) and surface area (from 272 to 119 m~2 g~(-1)) decrease, whereas the acid site density increases (from 1.4 to 2.4 sites per nm~2). Less coke, being the active catalyst, is formed during ODH on the AI-1000 sample compared to γ-Al2O3 (30.8 wt% vs. 21.6 wt%), but the coke surface coverage increases. Compared with γ-Al2O3, the EB conversion increased from 36% to 42% and the ST selectivity increased from 83% to 87%. For an optimal ST selectivity the catalyst should contain enough coke to attain full conversion of the limiting reactant oxygen. The reactivity of the coke is changed due to the higher density and strength of the Lewis acid sites that are formed by the high temperature calcination. The AI-1000 sample and all other investigated catalysts lost ODH activity with time on stream. The loss of selectivity towards more CO_x formation is directly correlated with the amount of coke.
机译：在500至1200°C之间的温度下，将市售的γ-Al2O3有般性钙化，并在氧化性乙烯苯脱氢（ODH）中测试了其在各种工业相关的条件下的性能。测试了原始的γ-Al2O3以及T |和α-Al2O3。事实证明，在1000/1050°C左右的钙化温度最适合ODH性能。钙化后，酸位点的数量（从637到436 nmol g〜（-1））和表面积（从272到119 m〜2 g〜（-1））减少，而酸位点密度增加（从1.4到1.4到2.4个站点每NM〜2）。与γ-Al2O3相比，在AI-1000样品的ODH中，可乐是活性催化剂（30.8 wt％vs. 21.6 wt％），但焦炭表面覆盖率增加。与γ-Al2O3相比，EB转化率从36％增加到42％，ST选择性从83％增加到87％。为了获得最佳的ST选择性，催化剂应含有足够的可乐，以使极限反应剂氧的完全转化。由于高温钙化形成的刘易斯酸位点的密度和强度较高，可口可乐的反应性发生了变化。随着时间的流逝，AI-1000样品和所有其他研究的催化剂失去了ODH活性。对更多CO_X形成的选择性丧失与可口可乐的量直接相关。

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