The STEREO (Effective point-of-use Sterilization of medical equipment using Ethylene Oxide) project was an 18-month research initiative funded by GCRF, aimed at developing an innovative on-demand production system for ethylene oxide (EO) from ethanol. The project brought together researchers from the University of Cambridge (UoC), University of Johannesburg (UJ), and Botswana Institute for Technology Research and Innovation (BITRI).
Project Motivation:
The project addressed a critical healthcare challenge highlighted by the COVID-19 pandemic: the shortage of effective sterilization methods for medical equipment and personal protective equipment (PPE), particularly in low-income countries. While EO is the most effective sterilizing agent for heat-sensitive medical devices and enables safe reuse of PPE through low-temperature sterilization, it is not produced in Botswana and only in small quantities in South Africa. The STEREO project sought to enable decentralized, small-scale EO production using ethanol—a widely available, inexpensive chemical often produced locally from agricultural residues.
The project addressed a critical healthcare challenge highlighted by the COVID-19 pandemic: the shortage of effective sterilization methods for medical equipment and personal protective equipment (PPE), particularly in low-income countries. While EO is the most effective sterilizing agent for heat-sensitive medical devices and enables safe reuse of PPE through low-temperature sterilization, it is not produced in Botswana and only in small quantities in South Africa. The STEREO project sought to enable decentralized, small-scale EO production using ethanol—a widely available, inexpensive chemical often produced locally from agricultural residues.
Technical Approach:
The project employed a two-step catalytic process: first, dehydrating ethanol to ethylene, then converting ethylene to EO through epoxidation. The collaborative structure leveraged each institution’s expertise: UJ focused on ethanol dehydration, BITRI concentrated on ethylene conversion, and UoC coordinated both aspects to ensure comparable results across partners.
The project employed a two-step catalytic process: first, dehydrating ethanol to ethylene, then converting ethylene to EO through epoxidation. The collaborative structure leveraged each institution’s expertise: UJ focused on ethanol dehydration, BITRI concentrated on ethylene conversion, and UoC coordinated both aspects to ensure comparable results across partners.
Key Achievements:
BITRI’s research centered on developing and characterizing silver-supported strontium ferrite (Ag@SrFeO₃) catalysts for chemical looping epoxidation of ethylene. The team successfully synthesized these catalysts using solid-state methods and conducted comprehensive characterization using XRD, TGA, SEM, BET, and XPS analyses. The catalysts demonstrated reversible oxygen uptake and release capabilities—crucial for the chemical looping
BITRI’s research centered on developing and characterizing silver-supported strontium ferrite (Ag@SrFeO₃) catalysts for chemical looping epoxidation of ethylene. The team successfully synthesized these catalysts using solid-state methods and conducted comprehensive characterization using XRD, TGA, SEM, BET, and XPS analyses. The catalysts demonstrated reversible oxygen uptake and release capabilities—crucial for the chemical looping
Figure 1: Isaac N. Beas, Botswana Institute for Technology Research and Innovation.
process. The reactor system was connected to a Hiden mass spectrometer (HPR-20 R&D) for real-time mass spectral analysis of gas effluents during the reaction, enabling precise monitoring of reaction products and kinetics. Performance testing at 270°C revealed promising results: the Ag@SrFeO₃ catalyst achieved ethylene conversion rates of 9-15% with selectivity toward EO ranging from 23-34%. Importantly, the catalyst showed excellent regenerability—after in situ treatment at 650°C, it fully recovered its performance, matching that of fresh catalyst. This regenerative capacity is essential for industrial applications as it reduces costs and minimizes waste. This setup, featuring a Hiden mass spectrometer, demonstrates the effectiveness of monitoring the products generated from the reaction. The catalyst also demonstrated good
stability over extended operation, maintaining consistent performance from cycle 2 through cycle 12 in a 20-cycle test. The research validated three analytical methods (mass spectrometry, infrared spectroscopy, and gas chromatography) for product detection, with all showing comparable results, confirming the reliability of findings between UoC and BITRI.
Significance and Future Directions:
The project successfully validated chemical looping as a viable approach for small-scale EO production, with both laboratory reactors constructed and tested. The knowledge transfer between institutions proved highly effective, with BITRI and UJ teams able to compare their results directly with Cambridge’s established data. Beyond immediate COVID-19 applications, the project enhances small-scale chemical production from renewable resources in developing countries, creating opportunities for small to medium-sized enterprises to provide sterilisation services. Future work could explore using EO to produce valuable carbonates, such as dimethyl carbonate and ethylene carbonate—important chemicals for batteries in the growing electric vehicle industry—while simultaneously utilising CO₂, thereby adding an environmental benefit to the technology.
The project successfully validated chemical looping as a viable approach for small-scale EO production, with both laboratory reactors constructed and tested. The knowledge transfer between institutions proved highly effective, with BITRI and UJ teams able to compare their results directly with Cambridge’s established data. Beyond immediate COVID-19 applications, the project enhances small-scale chemical production from renewable resources in developing countries, creating opportunities for small to medium-sized enterprises to provide sterilisation services. Future work could explore using EO to produce valuable carbonates, such as dimethyl carbonate and ethylene carbonate—important chemicals for batteries in the growing electric vehicle industry—while simultaneously utilising CO₂, thereby adding an environmental benefit to the technology.
Project Summary by: Isaac N. Beas, Botswana Institute for Technology Research and Innovation, Botswana.
Paper Reference: Damba, C., Beas, I. N., Mapolelo, M. M., Darkwa, J. and Marek, E. J. (2024) ‘Mechano-synthesis of a AgSrFeO3 catalyst for epoxidation of ethylene in a chemical looping set-up.’ Materials Advances, 5(14) pp. 6007–6015. DOI: 10.1039/D4MA00485J.
Hiden Product: HPR-20 R&D.
