SEM-EDX and SAM-AES Investigations on Rochow Contact Masses

Ehrich, Heike; Born, D.; Richter, Karsten; Richter‐Mendau, J.; Lieske, H.

doi:10.1002/(sici)1099-0739(199703)11:3<237::aid-aoc557>3.0.co;2-4

Cited by 24 publications

(12 citation statements)

References 21 publications

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“…By our recent investigation, 11 on which we comment in this paper, we showed that the famous Rochow promoter zinc does not act as a real accelerator of the reaction rate. It turned out that zinc acts as a kind of structural promoter and rather as a moderator than as an accelerator.…”

Section: Introductionmentioning

confidence: 80%

“…Free silicon surface is necessary for the formation of Cu-Si surface species, which seem to be catalytically active and more important than X-ray-detectable Cu-Si phases such as Z-Cu 3 Si. 11,12 Moreover, we showed in this recent paper that the action of zinc has something to do with the presence or absence of impurities in the silicon. Contact masses based on highly pure silicon achieve a relatively high stable activity even in the absence of a promoter.…”

Section: Introductionmentioning

confidence: 95%

“…4) is covered predominantly by copper species after running the Rochow reaction, just as we found recently. 11 The copper surface concentration on this Appl. Organometal.…”

Section: Sem/edx Imagesmentioning

confidence: 99%

“…This picture corresponds fully to the results with CuCl 2 /Si tech /Zn, described previously. 11 Figure 6 gives another view of the CuCl 2 /Si tech /CsCl contact masses. This micrograph reveals surface structures like blisters and hollow balls, which doubtless result from species molten previously.…”

Section: Sem/edx Imagesmentioning

confidence: 99%

“…This behaviour is fully analogous to that of zincpromoted CuCl 2 /Si tech /Zn. 11 The SEM images help to understand these findings. CuCl 2 /Si tech lost its initially high activity within a short time, because its surface was severely blocked by copper species.…”

Section: Analogy Between Zinc and Alkalisalt Promotermentioning

confidence: 99%

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Interaction of alkali salt promoters and silicon impurities in Rochow contact masses

Ehrich¹,

Born

Richter‐Mendau³

et al. 1998

Appl. Organometal. Chem.

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Cesium chloride‐ and rubidium chloride‐promoted Rochow contact masses based on both technical‐grade and highly pure silicon have been investigated in the Rochow reaction and by REM/EDX surface analysis. The alkali‐salt promoters seem to act analogously to the well‐known zinc promoter, by localizing the reaction to distinct reactive areas and keeping free the surface area for the reaction, probably for the formation of catalytically active Cu–Si surface species. The alkali salts exhibited their promoting action only in combination with the impurities within the technical‐grade silicon. Otherwise, they acted as blocking poisons. The promoter action of alkali chlorides in contact masses based on technical‐grade silicon is possibly connected with the formation of salt melts, containing alkali chlorides and impurities. These melts, analogously to zinc chloride, could dissolve oxidic impurities from the silicon surface which otherwise would enhance the blocking of potentially active surface by extensive copper deposition. © 1998 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 95%

“…4) is covered predominantly by copper species after running the Rochow reaction, just as we found recently. 11 The copper surface concentration on this Appl. Organometal.…”

Section: Sem/edx Imagesmentioning

confidence: 99%

Section: Sem/edx Imagesmentioning

confidence: 99%

Section: Analogy Between Zinc and Alkalisalt Promotermentioning

confidence: 99%

See 3 more Smart Citations

Interaction of alkali salt promoters and silicon impurities in Rochow contact masses

Ehrich¹,

Born

Richter‐Mendau³

et al. 1998

Appl. Organometal. Chem.

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Effects of double promoters on direct synthesis of triethoxysilane in gas–solid stirred fluidized bed

Zhang

Hao

Yang

et al. 2011

Applied Organom Chemis

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The reaction of silicon with ethanol was carried out in a gas-solid stirred fluidized bed, with cuprous chloride prepared by a wet process as the catalyst. The effect of hydrogen fluoride and ethyl chloride addition on formation of triethoxysilane in the direct process was described and discussed. The catalytic activity was evaluated using online gas chromatography, X-ray diffraction and scanning electron microscopy to study the contact mass. The results show that the promoters hydrogen fluoride and ethyl chloride not only supplemented anions, but also depressed the catalytic activity of metallic copper. The comparison of technical-grade silicon and polycrystalline silicon showed many differences in reactivity, reaction rate and induction period. Furthermore, the yield, selectivity of triethoxysilane and reaction rate were improved significantly with additions of hydrogen fluoride and ethyl chloride.

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Effects of Multiple Promotion of the Direct Synthesis Contact Mass with P, Zn, and Sn on the Synthesis of Methylchlorosilanes

2009

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The Direct Synthesis, or Rochow Synthesis, involves the reaction of methyl chloride, CH 3 Cl (MeCl), with Cu-Si contact masses (promoted with 1-2% of Zn, Sn, and P) to form methylchlorosilanes. Flow reactor studies (1 bar MeCl at 300°C) showed that contact masses promoted with Zn, Sn, and P (triply promoted) demonstrated the highest Si and MeCl conversion at early reaction times. In situ infrared spectroscopy suggested that in contrast to the doubly promoted catalysts (where CH 3 groups were primarily bound to Si), surface CH 3 showed appreciable binding to the copper component of the triply promoted contact mass. This change in surface composition ultimately led to a drop in reactivity and selectivity of the triply promoted catalyst.

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SEM-EDX and SAM-AES Investigations on Rochow Contact Masses

Cited by 24 publications

References 21 publications

Interaction of alkali salt promoters and silicon impurities in Rochow contact masses

Interaction of alkali salt promoters and silicon impurities in Rochow contact masses

Effects of double promoters on direct synthesis of triethoxysilane in gas–solid stirred fluidized bed

Effects of Multiple Promotion of the Direct Synthesis Contact Mass with P, Zn, and Sn on the Synthesis of Methylchlorosilanes

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