Sustainable production of ammonia and formic acid using three chemical looping reactors and CO2 electroreduction cell

Abstract

Chemical looping reforming (CLR) is emerging as a promising technique with potential to produce useful chemicals while capturing carbon dioxide emissions. This study proposes a novel multigeneration system consisting of three-reactor CLR integrated with CO2 electroreduction cell to produce 13.3 kg/s commercial-grade of ammonia and 0.0113 kg formic acid/kg ammonia. In order to achieve the maximum use of waste heat and cold energy, the system also includes interconnected power generation cycles. The net power generation is 816.54 kJ/kg ammonia, along with 305 kg/s hot water at 80 °C. A technoeconomic analysis is conducted to economically assess the process and the results are compared with other studies. The results of technoeconomic analysis give a comparatively low levelized cost of ammonia equal to 0.48 $/kg. Furthermore, to understand the irreversibilities involved in the integrated process, a thermodynamic analysis is conducted in terms of conventional and advanced exergy analyses along with sensitivity analysis which help determine the practical limitations and opportunities for process improvement of the overall system. According to the results, the overall process exergy efficiency is 74.80% and the overall exergy destruction rate is 116338.53 kW. The results of advanced exergy analysis show strong interdependencies between the components of the system due to major endogenous exergy destruction rates. Additionally, the results are used to propose three distinct strategies for design optimization and process intensification. This work is the first to look at the potential of improving the sustainability index (SI) by using the results of an advanced exergy analysis.