关键词: CO₂ capture, Zeolitic imidazolate framework-8, Slurry, Bubble column, Scale-up

Abstract: The increasing concentration of CO₂ in atmosphere is deemed the main reason of global warming. Therefore, efficiently capturing CO₂ from various sources with energy conservation is of great significance. Herein, a series of experiments were carried out to successfully test the slurry-based ab-adsorption method for continuously capturing CO₂ in the large-scale cycled separation unit with cost-effect taking into account the scale-up criteria. A bubble column (with height 4900 mm and inner diameter 376 mm) and a desorption tank (with volume 310 L) are the essential components of the separation unit. The novel slurry used in this study was formed with zeolitic imidazolate framework-8 and 2-methylimidazole-water solution. The influence of operation conditions was investigated systematically. The results show that increasing sorption pressure and slurry height level, decreasing gas volume flow and sorption temperature are beneficial for separation processes. The volume fraction of CO₂ in the feed gas was also studied. Although the scale-up effect had been observed and it was found that it exerted a negative effect on CO₂ capture, depending on experimental conditions, CO₂ removal efficiency could still reach 85%-95% and the maximum CO₂ loading in the recycled slurry could be up to 0.007 mol·L^-1·kPa^-1. Furthermore, the slurry-based method could be operated well even under very moderate regeneration conditions (333 K and 0.05 MPa), which means that the novel approach shows greater energy conservation than traditional amine absorption methods.

Key words: CO₂ capture, Zeolitic imidazolate framework-8, Slurry, Bubble column, Scale-up