In Press, Accepted Manuscript, Available online 16 April 2007
文章Low-temperature CO oxidation on Au/fumed SiO2-based catalysts prepared from Au(en)2Cl3 precursor(H.G. Zhu, Z. Ma, J.C. Clark, Z.W. Pan, S.H. Overbury, S. Dai*, Applied Catalysis A: General, 2007)publish了。I'm the second author of that paper. 现就写作部份和文章的骨架作一介绍。
第三段介绍文献中宣称Au/SiO2不是“失败者”的“反例”。说到别人选用其它金前驱体、其它制备方法,发现Au/SiO2的活性很高。(注:这里用非常洗练的语言介绍别人的几个例子。每一个例子1-2句话,有点象文献小综述。这个做法非常必要,叫做place the current research in proper context,或者set the current finding in perspective,即:在前人成果的基础上来讨论自己的工作。)然后,说到我们最近用Au(en)2Cl3作为前驱体,把黄金负载在中孔氧化硅上,发现很活泼,文章已经发表在J. Phys. Chem. B上(这里的写作手法是如实说清楚我们已经用了类似方法把黄金放在中孔氧化硅上,而本文用的不是中孔,而是无定型的氧化硅)。与此同时,别人用同样的方法把黄金放在某种无定型氧化硅上,他们对样品做了详细表征,但是没有报道催化活性(这里的写作手法是既带着尊重的语气客观描述别人做了什么,又指出别人工作和自己本文的区别)。
For as-synthesized Au/SiO2, it contains a lot of organic fragments,
so there is no activity.
For H2 reduced Au/SiO2, it of course has something to do with the
reduction temperature.
We reduce Au/SiO2 in H2 at 150oC, and at that low temperature,
of course organic fragments cannot be completely desorbed and
combusted, because there is no oxygen.
So, these is still no activity.
We then further calcined the H2-reduced sample at 500oC in O2-He
to combust the organic fragments,
so there is high activity.
The idea that whether organic fragments are removed or not was
proved by TG/DTA and TPR/TPO experiments.
In TG/DTG, above 150oC (the H2-reduction temperature), there is
still lot of stuffs getting desorbed, so reduction at 150oC is not
enough for complete removal of organics.
Using TPR/TPO, we actually can see what kind of molecues/products
can be decomposed/desorbed.
These experiments are interesting, because a lot of inorganic synthesis
chemists produced supported gold nanoparticles. They show
pretty TEM images, nice gold particles, but did not report activity,
or reported that the activity is really bad.
Why is that? Because they test the catalyst as it is, without pretreatment
to remove a lot of capping agents (which may contain organic sulfur
and something like that).
So, in some references, it was already mentioned that pretreatments
are necessary to get high activity.
[ Last edited by zhenmafudan on 2007-4-15 at 22:17 ]