Abstract
Climate action scenarios that limit changes in global temperature to less than 1.5 °C require methane controls, yet there are no abatement technologies effective for the treatment of low-level methane. Here, we describe the use of a biomimetic copper zeolite capable of converting atmospheric- and low-level methane at relatively low temperatures (e.g., 200-300 °C) in simulated air. Depending on the duty cycle, 40%, over 60%, or complete conversion could be achieved (via a two-step process at 450 °C activation and 200 °C reaction or a short and long activation under isothermal 310 °C conditions, respectively). Improved performance at longer activation was attributed to active site evolution, as determined by X-ray diffraction. The conversion rate increased over a range of methane concentrations (0.00019-2%), indicating the potential to abate methane from any sub-flammable stream. Finally, the uncompromised catalyst turnover for 300 h in simulated air illustrates the promise of using low-cost, earth-abundant materials to mitigate methane and slow the pace of climate change.
Highlights
The Intergovernmental Panel on Climate Change and the United Nations have recently published calls to action to reduce atmospheric methane emissions in order to slow the rate of global temperature change as quickly as possible.[1,2]
In an attempt to reduce overoxidation to CO2, researchers have employed extreme oxygen levels (e.g., 100%) in a two-step process of catalyst oxidation followed by reaction with high levels of methane, which is irrelevant to deployment in the environment and not representative of the evolutionary optimum of methane monooxygenase (MMO)
The ability to operate at low levels of methane and oxygen would expand the application space for the catalyst where it is most needed and across a spectrum of methane sources. Recognizing that this chemistry is desirable from the perspective of atmospheric methane abatement, we investigated copper-doped zeolites in methane oxidation at low temperatures and atmospheric gas compositions, seeking to provide an urgently needed tool to combat global climate warming
Summary
The Intergovernmental Panel on Climate Change and the United Nations have recently published calls to action to reduce atmospheric methane emissions in order to slow the rate of global temperature change as quickly as possible.[1,2] The reason methane is uniquely well suited to bring urgently needed reductions in climate warming rates is because methane has a pronounced radiative forcing effect in the near term: instantaneously, methane is 120 times as powerful a warmer as CO2 on a per-mass basis and exhibits a 28−34-fold greater global warming potential even after 100 years.[3,4] By. In an attempt to reduce overoxidation to CO2, researchers have employed extreme oxygen levels (e.g., 100%) in a two-step process of catalyst oxidation followed by reaction with high levels of methane, which is irrelevant to deployment in the environment and not representative of the evolutionary optimum of MMOs (i.e., low levels of methane and oxygen). It is precisely the acceleration of conversion of methane to CO2 that could dramatically reduce net radiative forcing and overcome the practical challenges associated with methanol production. Recognizing that this chemistry is desirable from the perspective of atmospheric methane abatement, we investigated copper-doped zeolites in methane oxidation at low temperatures and atmospheric gas compositions, seeking to provide an urgently needed tool to combat global climate warming
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