silicon for the chemical and solar industry XIII

Conclusions

A specific experimental lab procedure was developed to get information on catalyst

transport from activated to fresh silicon particles. Parameters influencing copper

transport in the methylchlorosilane reactor and reaction performances of the catalytic

sites resulting from this transport were investigated.

It was observed that the amount of copper transported from activated to unactivated

silicon was quite low and was only slightly affected by experimental conditions. In

any conditions, copper was distributed quite evenly at the silicon surface.

Cocatalysts transfer seemed more affected by experimental conditions: High

concentration of tin on added silicon fraction seemed correlated with transfer at high

temperature; high concentration of tin and zinc were obtained when the cocatalysts –

or zinc alone – were added during the transfer step.

The reactivity of the catalytic sites obtained by transfer was significantly higher – up

to 10 times higher - than the reactivity of the catalytic site obtained by reaction

between silicon and fresh catalyst.

Best reactivities were achieved at relatively low concentrations of cocatalysts.

High concentrations of cocatalysts is suspected of being the main factor degrading the

reactivity of fresh silicon.

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