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请教催化大牛一个简单问题 (转载)
[版面:化学][首篇作者:yijijuechen] , 2009年06月10日11:23:45 ,505次阅读,3次回复
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yijijuechen
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发信人: yijijuechen (yijijuechen), 信区: Chemistry
标  题: 请教催化大牛一个简单问题 (转载)
发信站: BBS 未名空间站 (Wed Jun 10 11:23:45 2009, 美东)

【 以下文字转载自 ChemEng 讨论区 】
发信人: yijijuechen (yijijuechen), 信区: ChemEng
标  题: 请教催化大牛一个简单问题
发信站: BBS 未名空间站 (Wed Jun 10 11:23:10 2009, 美东)

小弟现在开始做用水和CO2重整甲烷的实验,我看到很多文献报道用BaO去修饰载体,以
提高活性和防止碳沉积,我不太明白,难道BaO不和水和CO2反应吗?催化剂应该失活才
对,谢谢大牛指点
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figment
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发信人: figment (haha), 信区: Chemistry
标  题: Re: 请教催化大牛一个简单问题 (转载)
发信站: BBS 未名空间站 (Wed Jun 10 12:06:02 2009, 美东)

BaO is not the active component, it is the promoter. There must be other
transition metals as the main active components for your catalysts.
Basically, alkaline metals, such as K, Ba etc., are used to adjust the
electronic properties of the active metals by their interaction with the
main components, thus affecting the catalytic performance .

You are asking if BaO reacts with CO2 to form BaCO3, if I understand
correctly. Well, that might happen. The point is the nature of the active
components. After your BaO is mixed with the active component on the support
at elevated temperature, BaO only has the stoichiometrical meaning, it does
not indicate that the BaO still has its original crystalline structure. So
if your BaO is not the original BaO, God knows what is going to happen.

BTW, I answer your question not because I am a COW. No one is a COW.

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yijijuechen
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发信人: yijijuechen (yijijuechen), 信区: Chemistry
标  题: Re: 请教催化大牛一个简单问题 (转载)
发信站: BBS 未名空间站 (Wed Jun 10 12:26:07 2009, 美东)

谢谢你的详细回答,
非常有可能,BaO可能已经进入到其他氧化物的晶格,比如说Ni/CeO2-BaO,这个体系已
经生成BaCeO3,但是BaCeO3在水和二氧化碳中非常不稳定,最终催化剂还是变成CeO2和
BaCO3,这能否说明其实起到作用的很有可能是碱性的元素,它处于什么化合物当中,不
重要
比如说Ni/CeO2-BaCeO3 的催化活性可能相似,
谢谢
【 在 figment (haha) 的大作中提到: 】
: BaO is not the active component, it is the promoter. There must be other
: transition metals as the main active components for your catalysts.
: Basically, alkaline metals, such as K, Ba etc., are used to adjust the
: electronic properties of the active metals by their interaction with the
: main components, thus affecting the catalytic performance .
: You are asking if BaO reacts with CO2 to form BaCO3, if I understand
: correctly. Well, that might happen. The point is the nature of the active
: components. After your BaO is mixed with the active component on the
support
:  at elevated temperature, BaO only has the stoichiometrical meaning, it
does
:  not indicate that the BaO still has its original crystalline structure.
So
: ...................



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figment
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发信人: figment (haha), 信区: Chemistry
标  题: Re: 请教催化大牛一个简单问题 (转载)
发信站: BBS 未名空间站 (Wed Jun 10 21:24:46 2009, 美东)

In addition to your thinking of the interaction between the support and
promoters, here are my two cents: (1) people usually focus more on the
interaction between the active Ni and Ba promoter, possibly some crystalline
phase such as Ni-Ox-Ba, (2) the charge transfer between the ceria and the
active sites. You are interested in the substitution of Ce by Ba in the
support, note that Ce is 4+ and Ba is 2+.  
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