| dc.description.abstract | Annual global average temperatures in the past year have already exceeded the international target limit of 1.5°C, and the window to prevent that rise from extending is rapidly closing. The high global warming potential (GWP) and short atmospheric residence time (half-life of around 12 years) of methane make it a critical target for action to slow the pace of climate change in this decade. Yet technological solutions for methane abatement are challenged by methane’s inertness, dilute atmospheric concentrations, and diffuse, variable emissions sources. In this thesis, I propose the use of a bio-inspired, earth-abundant, heterogeneous catalysts as a novel tool for atmospheric and emissions-based methane abatement. Copper zeolites were characterized for their ability to convert low levels of methane, continuously, at low temperatures, for moderate durations, and in the presence of a variety of gaseous mixture influents, designed to mimic atmospheric air at standard temperatures and pressures. Catalytic performance was tested under conditions designed to mimic those found at two of the primary sources of low-level, anthropogenic emissions: ventilation air methane (VAM) and industrial dairy. Laboratory synthesized catalysts were shown to completely oxidize methane at concentrations ranging from atmospheric to 1%, covering the range of subflarable levels. Conversion was demonstrated at temperature as low a 270°C, with complete conversion achievable as low as 350°C, in the presence of 20% oxygen. While the presence of water vapor, nitric oxide, and hydrogen sulfide were shown to partially reduce catalytic efficiency, conversion efficiency was restored with increased temperature. The presence of carbon dioxide, alkanes, ammonia and hydrogen, at industrially relevant concentrations, had no effect on catalytic performance. Finally, atmospheric samples were collected at six industrial scale dairy barns across the Midwest and compared with the simulated laboratory conditions. Dairy samples fell within the ranges tested at the bench scale showing no evidence of any impediment to copper zeolite as a potential abatement tool. Methane concentrations at dairies were shown to be on the order of atmospheric to low 10s of ppmv making copper zeolites the only currently identified abatement strategy to address methane emissions at these locations. While it remains to be shown that these zeolites can provide net greenhouse gas benefit in the conditions required, copper zeolites are a strong option on a short list of technologies to address methane at any subflarable concentration, sources of which comprise 80% of global emissions sources, showing great promise as a climate technology breakthrough. | |
