Micrometric BN powders used as catalyst support: influence of the precursor on the properties of the BN ceramic
Micrometric BN powders used as catalyst support: influence of the precursor on the properties of the BN ceramic
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DOI：
10.1016/j.jssc.2003.05.007
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发表时间：
2004-02-01
影响因子：
3.3
通讯作者：
Bonnetot, B
中科院分区：
文献类型：
--
作者：
Perdigon-Melon, JA;Auroux, A;Bonnetot, B
由分子前体制备了氮化硼的薄粉末和泡沫，用作甲烷催化转化中的贵金属载体。已经测试了源自环硼氮烷的不同前体。最好的结果是使用从三氯硼氮（TCB）衍生的前体获得的，在室温下与氨反应，然后热处理至1800 ℃后，导致BN粉末的比表面积超过300 m（2）g（-1）和微米球形织构。在类似条件下使用聚硼氮烯获得了可比较的结果。氨基硼氮衍生的前体没有产生这样的高比表面积陶瓷，但BN微观结构类似于具有结晶皮肤和非晶内部部分的泡沫。这些差异与前驱体转化为BN的化学机理有关。聚卤代硼氮烷和聚硼氮烷通过气-固反应生成BN，而氨基硼氮烷聚合物在高温下可以保持蜡状，这有利于玻璃状泡沫。由BN载体和铂组成的催化剂已经使用两种途径制备：从前体的混合物或通过浸渍BN粉末，导致非常不同的催化剂。(C)2003年爱思唯尔公司All rights reserved.
Thin powders and foams of boron nitride have been prepared from molecular precursors for use as noble metal supports in the catalytic conversion of methane. Different precursors originating from borazines have been tested. The best results were obtained using a precursor derived from trichloroborazine (TCB) which, after reacting with ammonia at room temperature and then thermolyzing up to 1800degreesC, led to BN powders with a specific area of more than 300 m(2) g(-1) and a micrometric spherical texture. Comparable results were obtained using polyborazylene under similar conditions. Aminoborazine-derived precursors did not yield such high specific area ceramics but the BN microstructure resembled a foam with a crystallized skin and amorphous internal part. These differences were related to the chemical mechanism of the conversion of the precursor into BN. Polyhaloborazines and polyborazines yielded BN through gas-solid reactions whereas aminoborazine polymers could be kept waxy up to high temperatures, which favored the glassy foam. Catalysts composed of BN support and platinum have been prepared using two routes: from a mixture of precursor or by impregnation of a BN powder leading to very different catalysts. (C) 2003 Elsevier Inc. All rights reserved.