Optimal carbon dioxide and hydrogen utilization in carbon monoxide production

Abstract

Carbon monoxide is the building block of many relevant chemical products. However, the relatively high emissions (1.396–2.322 kg CO2-eq/kg CO) of its synthesis and separation process result in high emitting derivatives. Therefore, reducing CO synthesis emissions is the first step towards more sustainable end products. In order to tackle this problem, we propose a carbon monoxide synthesis and purification superstructure. We perform multi-objective optimizations minimizing the cost and emission of the final CO product across several case scenarios. Results show that the minimum cost solutions are achieved using partial oxidation of methane (POX) as the syngas synthesis process and cryogenic distillation as the CO separation technology. Emissions can be decreased using dry methane reforming (DMR) and pressure swing adsorption (PSA) but costs increase dramatically. Optimal H2 utilization results in a reverse water gas shift (RWGS) reactor where CO2 is consumed to produce additional CO. Off-gas valorization is key to further reducing the synthesis cost and emissions.