Development of evaluation methods and computer-aided analysis tool for sustainable $CO_2$ conversion processes

Abstract

Carbon dioxide ( $CO_2$ ) conversion technologies have come into the limelight lately as one of the solutions to global warming and climate change by reducing atmospheric $CO_2$ emissions. It aims to utilize $CO_2$ as feedstock to produce valuable chemicals via chemical reactions and generate economic benefits by selling the products. Although many ideas of $CO_2$ conversion technologies have been suggested, it is not clear which are promising for $CO_2$ reduction. To identify promising ones, it is important to verify feasibilities of $CO_2$ conversion technologies by proper evaluation, especially at the process level. Nevertheless, the evaluation is challenging due to the absence of key criteria and relevant feasibility conditions. Also, the absence of analysis tools designed for sustainable $CO_2$ conversion process design is another challenge. To tackle these challenges, the evaluation of $CO_2$ conversion processes intended to be designed for $CO_2$ reduction is mainly focused in this dissertation. The evaluation methods and the computer-aided analysis tool ($CATAC^3$) are developed to support the design of sustainable $CO_2$ conversion processes. Also, as case studies, two exemplary $CO_2$ conversion processes are evaluated. Combined reforming of methane and $CO_2$ hydrogenation technologies for methanol production are considered as $CO_2$ conversion technologies. Also, it is assumed to capture $CO_2$ at a hydrogen plant. Two methanol plants employing each conversion route are designed and simulated to obtain raw data for their evaluations. Following the evaluation methods formalized in this study, their feasibilities are verified in terms of net $CO_2$ emission and profitability. In addition, their implementation strategies for achieving $CO_2$ reduction are suggested. On the other hand, a new $CO_2$ conversion process utilizing a $CO_2$ -containing off-gas stream is designed and evaluated. Lastly, some perspectives of application of the developed evaluation methods and the analysis tools are discussed.