The neutralization of silane sih4 is carried out under strict oxygen control. With 20% sodium hydroxide solution (flow rate ≥8L/min), 1kg silane can be completely dissolved into sodium silicate and hydrogen in 23 seconds with a reaction efficiency of 99.97%. Basf’s industrial treatment process has real-time pH measurement (±0.1 accuracy) and temperature control (±1 ° C), with a resulting purity of 98.5% of the by-product sodium silicate, which can be recycled into glass production at the cost of $420 per ton of treatment, 68% less than the cost of conventional incineration. The 2023 statistics on TSMC plant incident showed that the un-neutralized leak of 0.3kg silane sih4 caused a fire, which underlines the importance of precise control.
The high temperature incineration technology shall have the temperature of the combustion chamber ≥1,200℃, residence time > 0.5 seconds, accompanied by SCR denitration system (ammonia escape rate < 2.5ppm) and ceramic filter (dust emission < 5mg/m³). The exhaust gas treatment equipment at Tokyo Electronics in Japan increases the silane combustion rate to 99.99%, while energy consumption is up to 3.8MWh/ ton and the carbon emission factor is 4.2 tons CO2/ ton. China GB 16297-2023 specifies that the silica dust content in incineration exhaust gas should be < 10mg/m³, and the environmental penalty rate of a semiconductor factory has been increased from 78% to 99% after refurbishment, and the environmental penalty reduced by ¥8.7 million per year.
The plasma decomposition technology has made breakthroughs of great importance, and 3M has developed an atmospheric pressure plasma reactor with which 98g silane sih4/h can be decomposed under power of 400W, and the ratio of energy utilization is 3.2 times that of the traditional method. Samsung’s South Korea test data show that the technology will specify the particle size of nano-silicon particles in decomposed products to 30-50nm (ordinary incineration technology 200-300nm), added-value application in lithium battery anode material manufacturing, per-kilogram processing cost is 58, but equipment investment is 2.8 million/MW. The EU BAT (Best Available Technology) Directive of 2024 considers plasma as a best technology, and the coverage will be 45% by 2030.
Adsorption and recovery technology has been developed. MOF-808 metal organic framework material adsorbed silane sih4 to 14.3mmol/g capacity at 25℃, the desorption temperature was only 80℃, and the loss of performance was less than 3% after 200 cycles. The in-house designed continuous adsorption equipment of the Chinese Academy of Sciences had a recovery ratio of silane 95%, purity 99.99%, and regeneration cost 1,200/ton, i.e., saved 2,600 by new purchase. Besides, for the treatment of exhaust gas, however, the content of the residue should be below 1ppm or else secondary burning is still needed, while the additional cost is $180/ton.
Biological treatment technology is now in the experimental stage. Methylococcus capsulatus Bath, methane-oxidizing strain screened by Lawrence Laboratory of America, was capable of converting silane sih4 to silica and methane with the conversion rate as high as 82% at 30℃, but with a processing rate as low as 0.12g/L·h. Industrialization requires the reactor capacity to be 370 times increased. A 2023 Nature paper revealed that the silane metabolic enzyme activity of the gene edited strain was 3.8-fold greater, although the stability of the biofilm persisted for just 72 hours, still 5-8 years from being practically applicable.
Regulatory needs drive technological innovation, and the EU IED Directive requires VOCs removal efficiencies of silane treatment systems to be ≥99.9%, which is achieved after retrofitting a photocatalytic oxidation system (specific surface area of the TiO2 coating being 320m²/g) in a German plant but at the expense of needing to regenerate the catalyst every 600 hours and an annual maintenance cost of €280,000. New environmental regulations by the Ministry of Ecology and Environment in 2024 will increase the minimum distance from 500 meters to 800 meters between treatment plants and residential areas, forcing 12% of small and medium-sized businesses to shut down for reconstruction. According to OSHA statistics, standardized treatment has reduced the accident rate involving silane from 0.17 cases per 10,000 tons to 0.003.
Recycling has created new value, and the recovered nano silicon powder (99.9% purity) has a market value of 120/kg, which can be used in lithium-ion batteries to increase anode capacity by 2715,000, covering the cost of treatment by 38%. However, market volatility is very high, and the photovoltaic grade silicon price in 2023 reduced by 42%, leading to a reduction of $580/ ton of resource income.
The emergency neutralization process requires a quick response, and the use of a spray system consisting of 10% citric acid solution (15L/min·m³) can reduce the silane concentration in the leak zone to a safe value (25ppm) from 5,000ppm within 12 seconds. Norsk Vert-certified robotic emergency system, with an infrared gas imager (detection limit 0.5ppm) and robotic arm (positioning accuracy ±2mm), mitigated a 1.2kg leak incident in 2022 by preventing 3.8million losses. The maintenance expense of a trained emergency team can be as high as 280,000/year, whereas smes opt for third-party services ($12,000-18,000 per disposal).