Carbon monoxide separation by reactive absorption in chlorocuprate(I)-based ionic liquid

摘要

1.Introduction High amounts of CO are often release in the waste gas streams of industrial processes when a partial combustion of hydrocarbons is performed, e.g. carbon black manufacturing, steel-making and silicon carbide processes. The selective recovery and valorisation of this CO could be sought as a means to obtain a valuable by-product such as hydrogen or chemicals, e.g. methanol, formaldehyde, etc. Available technologies at commercial scale to address the CO separation are based on cryogenic distillation, liquid absorption, and adsorption processes. Nevertheless, if nitrogen is present in the gas mixture, the use of an absorption process may be considered as the most attractive technology at medium scale given that cryogenic distillation becomes less efficient with increasing N_2 content and pressure swing adsorption process has a lower yield [1]. Nowadays, the CO absorption process is based on the complexation/decomplexation reaction between CO and copper(I) aluminum chloride salt (CuAlCl_4) dissolved in an aromatic hydrocarbon, usually toluene, and has several concerns regarding the solubility of the complexing salt and its long-term activity. In this work, a novel approach to the separation and purification of CO is explored taking advantage of the outstanding properties offered by ionic liquids, namely, their negligible vapour pressure, high solvent capacity, wide liquid range and thermal and chemical stability.