Catalytic formation of silanes on copper-silicon alloys
Areal rates of silane formation from CH 3Cl and silicon were measured in a differential batch reactor at atmospheric pressure and 520–620 K, on three clean, nonporous, silicon-containing surfaces. These surfaces were characterized with Auger spectroscopy by transferring them directly between UHV and...
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Published in | Journal of catalysis Vol. 91; no. 1; pp. 44 - 53 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Elsevier Inc
1985
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Online Access | Get full text |
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Summary: | Areal rates of silane formation from CH
3Cl and silicon were measured in a differential batch reactor at atmospheric pressure and 520–620 K, on three clean, nonporous, silicon-containing surfaces. These surfaces were characterized with Auger spectroscopy by transferring them directly between UHV and atmospheric pressure, without exposure to air. On pure silicon, a long induction time was seen before steady-state reaction; the main products at steady-state were HSiCl
3 and CH
3HSiCl
2. On Cu
3Si and Cu
3Si containing 0.4 atm% Zn, the overall silane formation rates were an order of magnitude lower than on pure silicon. Copper catalyst, however, dramatically increased selectivity to 85% (CH
3)
2SiCl
2, the desired product for silicone production. Copper also decreased the induction time by increasing the rate of active-site formation. Zinc promoter in Cu
3Si further increased (CH
3)
2SiCl
2 selectivity to 95% without significantly changing activity. No induction time was seen with the Zn promoter. Silicon diffusion in Cu
3Si limited silane formation, and a mathematical model is presented. Reaction on Cu
3Si containing Zn was not limited by diffusion. These are the first measurements of silane direct-synthesis kinetics on Cu
3Si of known surface area, and they show directly that Cu
3Si provides an active surface for selective formation of (CH
3)
2SiCl
2. Rates and selectivities on the alloys were similar to those measured for higher-surface-area solids. |
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ISSN: | 0021-9517 1090-2694 |
DOI: | 10.1016/0021-9517(85)90286-6 |