P.M. Kester
Guild Associates, Inc.,
United States
Keywords: gas-phase PFAS, catalytic destruction, PFAS abatement, advanced materials
Summary:
Gas-phase PFAS emissions are significant byproducts of treating PFAS-laden solids and liquids from landfills, wastewater treatment plants, and remediation systems such as incinerators. These emissions arise from vented aerosols, incomplete PFAS destruction, or passive transport from PFAS-laden wastes. Their persistence and bioaccumulation pose health risks including thyroid disease, cancer, and reduced vaccine response. Once released, gas-phase PFAS can travel hundreds of miles, contributing to widespread contamination. Occupational exposure and environmental pollution from atmospheric conversion of gas-phase PFAS to species with lower vapor pressures, including perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), highlights the need for on-site destruction to eliminate airborne exposure routes. Traditional thermal PFAS abatement requires high temperatures (>1000°C) and specialized equipment, limiting field deployment. To overcome these limitations, Guild Associates has developed a novel alumina-based catalyst that destroys gas-phase PFAS at significantly lower temperatures than thermal technology. The catalyst enables surface-catalyzed PFAS hydrolysis, forming CO2 and HF, which are easily managed with conventional acid gas scrubbing systems. It destroys ~99% of CF4 at 675°C under typical flow conditions, far below the 1200°C needed for conventional systems. These lower operating temperatures decrease energy requirements, reduce needs for specialty materials, and alleviate thermal NOx formation. Guild’s catalyst also enables low-temperature destruction of large volatile PFAS, including 8:2 fluorotelomer alcohol (8:2 FTOH) and NEt-FOSE. Destruction of 99% of 8:2 FTOH at ~350°C has been demonstrated, compared to ~700°C without the catalyst under otherwise identical conditions. Similar results were observed with NEt-FOSE. Guild’s catalyst is competent at destroying both large and small PFAS present in exhaust streams. The catalyst’s non-selective nature is critical, as partial decomposition of bulky PFAS would otherwise require further high-temperature treatment for complete destruction. Guild’s PFAS destruction catalyst is stable under reaction conditions for extended periods, allowing prolonged use without frequent replacement. Rapid deactivation has traditionally hindered the adoption of catalytic PFAS abatement technology, with only recent advancements being made in laboratory-scale synthesis of stable catalyst formulations. In contrast, Guild’s formulation has shown long-term viability in a five-month pilot study at a semiconductor manufacturing facility, destroying more than 99.5% of CF4, 99% of C2F6, and 97% of c-C4F8 without measurable deactivation. Judicious selection of catalyst composition and processing methods engender stability under reaction conditions. Accelerated deactivation testing showed that the optimized catalyst maintained stable performance for over 100 hours, while a non-optimized version deactivated after ~10 hours. This result underscores the relationships between industrially relevant catalyst synthesis protocols and the structure and performance of the resulting catalyst. Guild’s PFAS destruction catalyst enables next-generation catalytic abatement systems, meeting emission reduction and energy efficiency targets by replacing incumbent technologies. Its ability to destroy both long- and short-chain PFAS at low temperatures eliminates undesirable byproducts associated with conventional abatement technologies (e.g., NOx, F2, OF2) and reduces capital and operating costs.5