Ultramicroporous carbon materials with Ångstrom-precise pore engineering offer a transformative solution for separating fluorinated gases like C3F6 (fluorinated propylene) and C3F8 (fluorinated propane). A team of scientists has synthesized the CO2-activated porous carbon adsorbents derived from a precursory resin and systematically investigated their molecular sieving behavior for C3F6/C3F8 mixtures. Through controlled thermal pyrolysis and stepwise CO2 activation, they tailored ultramicropore size distributions to selectively exclude or admit target molecules. Their work is published in the journal Industrial Chemistry & Materials on 24 Jun 2025.
"We've engineered ultramicroporous carbon materials that selectively trap impurities while achieving the purification of the target gas," explains Zongbi Bao, a professor at Zhejiang University. His team developed carbon molecular sieves with tuned pores using CO2 activation, solving a critical challenge in semiconductor manufacturing: purifying C3F8, a gas essential for etching microchips in AI and 5G devices.
Electronic specialty gases (ESGs) must be ultra-pure (99.999%) to prevent nanoscale defects in chips. However, C3F8 production always contains 1-10% C3F6 impurities. These gases have near-identical sizes and boiling points, making conventional distillation energy-intensive and economically unviable. Existing solutions—zeolites or metal-organic frameworks (MOFs)—suffer from poor tunability, high regeneration costs, or structural fragility.
Inspired by the mechanism of molecular sieving, the team synthesized phenolic resin-derived carbons activated under controlled CO2 atmospheres. By adjusting CO2 concentration (5–25 vol%), they engineered pore sizes with Ångstrom-level accuracy. Optimal activation (15% CO2) created 6.5 Å pores that admit C3F6 while completely blocking C3F8. Consequently, the material (PRC-15 CO2) achieved a record C3F6/C3F8 uptake ratio of 70.48—2–5× higher than some MOFs—and produced 99.999% pure C3F8 at industrial scales.
This technology is critically important because semiconductor manufacturing consumes terawatts of energy yearly; it significantly cuts purification energy by replacing multi-step distillation with single-pass adsorption, enabling milder regeneration at 180°C compared to 280°C required for zeolites, and slashing processing time as C3F6 diffusion versus conventional carbons. Demonstrating its industrial potential, PRC-15CO2 processed 394 liters of high-purity (5N-grade) C3F8 per kilogram from crude mixtures, operating 4 times more efficiently than commercial adsorbents.
The team envisions adapting these "molecular sieving" for other challenging separations, such as propylene/propane or CO2 capture. "Precision pore engineering via CO2 activation is a universal design principle," says Dr. Lihang Chen. "We're scaling production to industrial levels to support greener electronics manufacturing."
The research team includes Yiwen Fu, Liangzheng Sheng, Wei Xia, Guangtong Hai, Jialei Yan, Lihang Chen, Qiwei Yang, Zhiguo Zhang, Qilong Ren, and Zongbi Bao from Zhejiang University and Institute of Zhejiang University-Quzhou.
This research is funded by the National Natural Science Foundation of China, the Zhejiang Provincial Natural Science Foundation of China, and the Zhejiang Provincial Innovation Center of Advanced Chemicals Technology.
Industrial Chemistry & Materials is a peer-reviewed interdisciplinary academic journal published by Royal Society of Chemistry (RSC) with APCs currently waived. ICM publishes significant innovative research and major technological breakthroughs in all aspects of industrial chemistry and materials, especially the important innovation of the low-carbon chemical industry, energy, and functional materials. Check out the latest ICM news on the blog .
