CHE.11 – From Grit to Gigabytes: Producing 6N-Purity Silane from Coal and Sand

• Karim Al Zahabi
• Ramiro Maldonado
• Monica Rochnowski

Recent breakthroughs in artificial intelligence and data processing, fueled by the rapid expansion of processing centers by tech giants like NVIDIA and Google, have ignited a soaring demand for computational hardware. To remain at the forefront of innovation, these companies depend on the availability of ultra-pure materials such as electronic-grade silane gas, which is essential for the manufacturing of the semiconductor chips that power these cutting-edge systems. In this contribution, we seek to meet the surging demand by producing ultra-pure silane gas (99.9999%) in a cost-effective manner from simple raw materials. Our plant, located in Tongwei, China, is engineered to manufacture 20,000 metric tons of electronic grade silane annually by first liquefying coal and silicon dioxide (sand) in a rotary kiln, which react to yield metallurgical-grade silicon. The resulting mixture of silicon and chlorosilanes undergoes further reaction and is passed through two distillation columns to generate trichlorosilane. Finally, this trichlorosilane mixture is fed into two reactive distillation columns, where the ultra-pure silane product is produced and any unreacted chlorosilanes are recycled back into the system. The plant has a capital cost of $172 million and an operating cost of $232 million/year, largely due to the liquid nitrogen requirement for reactive distillation. Nevertheless, the final design generates an annual revenue of $62 million, resulting in a 20-year net present value of $816 million, and is thus a prime example of how basic, unrefined materials can be transformed into high-demand, ultra-pure products.