| Abstract Scope |
The substitution of solid carbon in silicon production is challenging. As an example, the reaction between SiO<sub>2</sub> and H<sub>2</sub> to Si is thermodynamically unfavourable below 4500 °C . However, the partial reduction to SiO gas is possible. In the Siemens process for high purity polysilicon production, the input is gas-based Si-species like SiH<sub>4</sub> or SiHCl<sub>3</sub>. Today, these species are produced from metallic silicon, but if they could be produced from SiO-gas and Cl<sub>2</sub> directly, there would be no need to produce metallic Si, and no need for the final, challenging reducing step from SiO to Si. In other words, it would be possible to eliminate the need for solid carbon as a reductant, and the associated CO<sub>2</sub>-emissions, in this part of the silicon market. The present work explores these possibilities and identifies the bottlenecks in a potential process. The work is based on thermodynamical calculations using FactSage. |