CO, an important greenhouse gas, is generated by a wide range of sources, including malfunctioning or improperly vented gas appliances (such as water heaters and furnaces), space heating, tobacco smoke and car and truck exhaust.co removal The CO concentration in indoor air can be much higher than outdoors.co removal This may be due to a combination of factors, such as the length of time that an appliance has been in use, the type and condition of the gas supply, and the humidity level.co removal
CO elimination is a critical technology for achieving net zero emissions.co removal Current CO elimination technologies, such as a cryogenic process (COSORB), a pressure swing adsorption system (P(V)SA) and porous media adsorption, require high energy consumption and produce large amounts of waste products.co removal These methods also lead to a significant loss of hydrogen.co removal
A new sorbent developed at the University of Maryland, Baltimore (UMB) provides an alternative.co removal The Mg13CuCeOx bead-structured sorbent has superior CO sorption capacity at low temperatures and can eliminate trace levels of CO from H2.co removal The UMB researchers found that the new sorbent performs up to 50 times better than existing powdered sorbents at absorbing CO at pressures below 10 kPa.
The sorbent also has good stability and a long breakthrough lifetime in eliminating CO from H2 at temperatures below 80 oC, a potential advantage over existing sorbents.co removal Moreover, the UMB researchers have shown that the sorbent can be thermally integrated with the CO2 capture process by utilizing the heat of adsorption for sorbent regeneration.co removal
An important challenge in co-removal is to provide a low energy penalty for methane conversion while minimizing the cost of carbon dioxide capture.co removal The authors have proposed a co-removal process that integrates the methane conversion step with the CO2 capture step using photocatalytic conversion in an oxygen-rich atmosphere.co removal The energy demand for the methane conversion and co-removal cases analyzed in this study is about 2.08 GJ/t-CO2eq removed, which is 7–20% lower than that of the methane conversion case without the CO2 capture step.
The co-removal process is applicable to streams with lean methane concentrations, which are the anthropogenic non-fossil methane from agriculture farms and natural methane emissions from wetlands.co removal Adding the CO2 capture step to the methane conversion steps would accelerate the achievement of net zero emissions targets for these streams.co removal However, a life cycle analysis (LCA) will be necessary to determine whether this approach is feasible and cost effective in practice. It will be important to examine the sensitivity of the proposed processes to the choice of materials for catalytic methane conversion, heat exchanger design and reactor conditions and the treatment of other impurities in the methane stream, such as ammonia and volatile organic compounds. This will help ensure that the methane conversion and CO2 capture processes are commercially viable and can be deployed for real-world applications. The LCA will also decide if this method can enable the achievement of negative emission targets. The authors are currently preparing a techno-economic study to assess the viability of this concept.
