Catalytic Dehydrogenation of Ethylbenzene in Helium and Reductive Dealkylation in Hydrogen on Nb, Mo, Ta, W, and Re Halide Clusters
Catalytic Dehydrogenation of Ethylbenzene in Helium and Reductive Dealkylation in Hydrogen on Nb, Mo, Ta, W, and Re Halide Clusters
复制标题
Nb、Mo、Ta、W 和 Re 卤化物簇上乙苯在氦气中的催化脱氢和氢气中的还原脱烷基化
DOI：
10.1023/b:jocl.0000021250.54969.a6
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发表时间：
2004
影响因子：
2.8
通讯作者：
T. Chihara
中科院分区：
文献类型：
--
作者：
S. Kamiguchi;S. Iketani;M. Kodomari;T. Chihara
具有八面体金属骨架的[(Nb6Cl12)Cl2(H2O)4]⋅4H2O和(H3O)2[(M6Cl8)Cl6]⋅6H2O(M=Mo，W)和具有三角形金属骨架的RE3Cl9在450°C的氦气氛中选择性地催化乙苯脱氢生成苯乙烯.在400℃以上，催化剂的活性随时间的延长而降低，苯选择性显著提高。活性的降低是由于副产物乙烯所产生的焦炭造成的。当相同结构的Nb和Ta团簇在氢气中以相同的方式处理时，没有进行催化反应。然而，在氢气催化乙苯还原脱烷基化反应中，Mo和W簇合物选择性地生成甲苯和苯。对于Mo团簇，其催化活性在400℃时出现，并随着温度的升高而增加。即使在高温下，该酶的活性也不随时间而降低。在氢气中处理后还原为金属的Re团簇催化开环降解生成气态碳氢化合物。
Halide clusters of [(Nb6Cl12)Cl2(H2O)4]⋅4H2O and (H3O)2[(M6Cl8)Cl6]⋅ 6H2O (M=Mo, W), which have an octahedral metal framework, and Re3Cl9, which has a triangular metal framework, developed catalytic activity for the dehydrogenation of ethylbenzene selectively to yield styrene when the halide clusters were treated in a stream of helium at 450°C. In the case of the Mo cluster, this catalytic activity appeared at 300°C. The activity increased with increasing temperature. Above 400°C, the catalytic activity decreased with time, and the selectivity for benzene increased noticeably. The reduction in the activity was caused by the formation of coke attributable to ethylene produced as a by-product. When the Nb and Ta clusters of the same structure were treated in a stream of hydrogen in the same way, no catalytic reaction proceeded. However, the Mo and W clusters in a stream of hydrogen catalyzed reductive dealkylation of ethylbenzene selectively yielding toluene and benzene. In the case of the Mo cluster, the catalytic activity appeared at 400°C, and increased with increasing temperature. The activity did not decrease with time even at high temperatures. The Re cluster, which was reduced to the metal by the treatment in hydrogen, catalyzed ring-opening degradation to yield gaseous hydrocarbons.