The issue of dichlorodihydrosilicon in distillation
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In distillation, the content of dichlorodihydrosilicon in the overhead product is quite high; in particular, it is around 10% in the distillation column for reducing off-gases. If a large amount of trichlorosilane is discharged through these off-gases, it will be carried away along with them. I would like to ask experts if there is any better way to handle this situation
Reply to 1# Li Jianraul: In fact, controlling the amount of dichlorodihydrosilicon at an appropriate level is beneficial for the reduction reaction
I agree with the comment above; if the volume is still too large, considering adding a heat exchanger for cooling would be a good option, and R22 as the heat transfer medium will suffice (at -35 degrees).
Two methods: 1, add a primary low-pressure distillation column; 2, collect the off-gases (secondary trichlorosilane) and purify them further
Adding a certain amount of dichlorodihydrosilane to trichlorosilane is beneficial for the reduction reaction; however, the exact proportion to be added depends on the conditions under which the reduction process takes place, and it will take some time running the reduction process before any effects can be observed. As early as the time of Motorola, polysilicon was produced by direct reduction using dichlorodihydrosilane, but on a much smaller scale; it seemed to involve coating a certain type of chip with a layer of polysilicon. So if the content of dichlorodihydrosilicon isn’t particularly high, there should be no problem.
Generally, this portion of exhaust gas is collected for further distillation and purification!