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

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

doi:10.1002/(sici)1099-0739(199703)11:3<237::aid-aoc557>3.3.co;2-w

Cited by 7 publications

(10 citation statements)

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“…We do not find the reactivity of the Si-Cu toward residual oxygen surprising based on prior studies that show the Si in the Si-Cu alloy (e.g., Cu 3 Si) is more susceptible to oxidation than is pure silicon [23]. We do not suspect that this residual oxidation affects our results considering that our selectivities and relative reaction rates derived from the reactor studies agree well with prior studies [5][6][7][8][9].…”

Section: In Situ Identification Of Surface Intermediates On the Ds Cosupporting

confidence: 76%

“…Because of the industrial importance of the DS for the production of silicones, there have been many prior studies that have mapped out the effects of promoters on the selectivity and reactivity of contact masses for the DS [2][3][4][5][6][7][8][9][10]. It is the general consensus from the literature that when specific combinations of promoters are added together, a synergism between the promoters is typically observed.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: In Situ Identification Of Surface Intermediates On the Ds Cosupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

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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“…51,52 It is believed that at the beginning of the reaction, Cu atoms, which are essentially mobile in the reaction system, 22 firstly diffuse on and into Si surface to form the active alloying Cu 3 Si species at the interface of Cu and Si. 23,53,54 These species are the precondition of the synthesis reaction, which play an important role in guiding the reactant-catalyst interaction towards a higher specificity of the reaction. 53,55 Meanwhile, promoter additives such as Zn, ZnO, and Sn are of importance in improving the catalytic performance, 29,33,56,57 which could decrease the segregation energy of Si and promote the crystal growth of Cu silicides.…”

Section: Catalytic Propertymentioning

confidence: 99%

“…23,53,54 These species are the precondition of the synthesis reaction, which play an important role in guiding the reactant-catalyst interaction towards a higher specificity of the reaction. 53,55 Meanwhile, promoter additives such as Zn, ZnO, and Sn are of importance in improving the catalytic performance, 29,33,56,57 which could decrease the segregation energy of Si and promote the crystal growth of Cu silicides. Fig.…”

Section: Catalytic Propertymentioning

confidence: 99%

Flower-like ZnO grown on urchin-like CuO microspheres for catalytic synthesis of dimethyldichlorosilane

et al. 2013

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“…Because of the obvious growth of the silicone industry in the past few decades, there has been evidence of a stable increase in the production of methylchlorosilanes (MCSs), which serve as the primary monomeric intermediates for the manufacture of silicone products via the Rochow reaction. 1,2 In this reaction, gaseous methyl chloride (MeCl) reacts with silicon (Si) in the presence of Cu-based catalysts as follows: [3][4][5] Si þ MeCl !…”

Section: Introductionmentioning

confidence: 99%

Heterojunctions generated in SnO₂–CuO nanocatalysts for improved catalytic property in the Rochow reaction

Shanying

Wang

et al. 2015

RSC Adv.

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We report the improved catalytic performance of SnO 2 -CuO hybrid nanocatalysts synthesized by rationally designing and controlling the local heterojunctions structure. The SnO 2 nanoparticles (NPs) decorated CuO nanorods (NRs) (SnO 2 -CuO) with a mace-like structure and with various CuO : SnO 2 ratios were prepared via depositing pre-synthesized SnO 2 NPs on CuO NRs in the presence of polyvinylpyrrolidone molecules. The CuO NRs were obtained by a facile hydrothermal reaction using Cu(NO 3 ) 2 •3H 2 O as the precursor. The samples were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and temperature-programmed reduction analyses. The results indicated that in the SnO 2 -CuO hybrid nanostructures, the heterojunctions were well generated as the SnO 2 NPs were well dispersed on the CuO NRs. Their catalytic performances were then explored via the Rochow reaction, in which solid silicon (Si) reacts with gaseous methyl chloride (MeCl) to produce dimethyldichlorosilane (M2). Compared to discrete CuO and SnO 2 as well as their physical mixture, the SnO 2 -CuO hybrids exhibit significantly enhanced M2 selectivity and Si conversion because of the enhanced synergistic interaction between SnO 2 and CuO due to the generated heterojunctions.This work demonstrates that the performance of heterogeneous catalysts can be improved by carefully designing and controlling its structures even maintaining the composition unchanged.CuO microspheres 17 have been prepared in our group as model catalysts for the Rochow reaction, and found that their catalytic performance mainly depends on the chemical composition, 18 particles size, 19 and surface structure. 16 However, the above catalysts still suffer from low M2 selectivity and/or Si conversion, which seriously hinder their further application. Therefore, more efficient Cu-based catalysts should be developed.Recently, CuO-based hetero-structured hybrid materials have caused strong attention owing to their distinct properties and high diversity in structure and composition. For instance, Avgouropoulos et al. prepared a series of CuO-CeO 2 catalysts which exhibited much better catalytic performance for the selective oxidation of CO than CuO alone. 20 Li et al. observed that the CuO-ZnO-ZrO 2 catalysts synthesized by a surfactant-assisted coprecipitation method showed higher catalytic activity than that of sole CuO as a result of more intimate contact at the interface between Cu species and ZnO and/or ZrO 2 . 21 More recently, we have grown flower-like ZnO on urchin-like CuO microspheres using a simple solvothermal method, and the hierarchical structure displayed better catalytic properties in M2 synthesis in comparison with the single CuO phase, probably because of the enhanced synergistic effect between ZnO and CuO. 22 However, the composite particles were still in the micrometer scale with limited particle contact and weak synergistic effect.On the other hand, to date there are few reports on preparing Cu...

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

Cited by 7 publications

References 0 publications

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

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

Flower-like ZnO grown on urchin-like CuO microspheres for catalytic synthesis of dimethyldichlorosilane

Heterojunctions generated in SnO₂–CuO nanocatalysts for improved catalytic property in the Rochow reaction

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

Cited by 7 publications

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

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

Flower-like ZnO grown on urchin-like CuO microspheres for catalytic synthesis of dimethyldichlorosilane

Heterojunctions generated in SnO2–CuO nanocatalysts for improved catalytic property in the Rochow reaction

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Heterojunctions generated in SnO₂–CuO nanocatalysts for improved catalytic property in the Rochow reaction